Note: Descriptions are shown in the official language in which they were submitted.
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NOVEL ELASTOMER COMPOSITES,
METHOD AND APPARATUS
Field of the Invention
The present invention is directed to novel methods and apparatus for
producins elastomer composites, and to novel elastomer composites produced
using
such methods and apparatus. More particularly, the invention is directed to
continuous flow methods and apparatus for producing elastomer masterbatch of
particulate filler finely dispersed in elastomer, for example, elastomer
composites of
carbon black particulate nller finely dispersed in natural rubber, such as
curative-free
masterbatch compositions, curative-bearing base compositions, and rubber
materials
and products formed of such masterbatch compositions.
'Ihis is a divi.siaz of Carxli..an PMlicatirn 2, 250, 774, filed Mai~ 25,
1997.
BackQround
Numerous products of commercial significance are formed of elastomeric
compositions wherein particulate filler is dispersed in any of various
synthetic
elastomers, natural rubber or elastomer blends. Carbon black, for example, is
widelv
used as a reinforcing agent in natural rubber and other elastomers. It is
common to
produce a masterbatcli, that is, a premixture of filler, elastomer and various
optional
additives, such as extender oil. Carbon black masterbatch is prepared with
different
grades of commercially available carbon black which vary both in surface area
per
unit weisht and in "structure." Numerous products of commercial siQnificance
are
formed of such elastomeric compositions of carbon black particulate filler
dispersed
in natural rubber. Such products include, for example, vehicle tires wherein
different
elastomeric compositions may be used for the tread portion, sidewalls, wire
skim and
carcass. Other products include, for example, engine mount bushings, conveyor
belts, windshield wipers and the like. While a wide ranae of performance
characteristics can be achieved employinc, currently available materials and
manufacturing techniques, the:e has been a lono standing need in the industry
to
develop elastometic compositions having improved properties and to reduce the
cost
and complexity of current manufacturing technioues. In particular, it is known
for
example that macro-dispersion level, that is, the uniformity of dispersion of
the
carbon black or other filler within the elastomer, can sisnificantly inlpact
performance
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WO 97/36724 PCTJLTS97/Q5276
characteristics. For elastomeric compositions prepared by intensively mixina
the
carbon black or other filler with natural rubber or other elastomer (such as
in a
Banbury mixer or the lil:e), any increase in macro-dispersion requires longer
or more
intensive mixing, with the consequent disadvantages of increased energy costs,
manufacturing time, and similar concems. For carbon black fillers of certain
surface
area and structure characteristics, dispersion beyond a certain dearee has not
been possible or commercially practicable using known mixing apparatus and
techniques.
In addition, such prolonged or more intensive mixine degrades the natural
rubber by
reducinc, its molecular weight, renderina the finished elastomeric compound
] 0 undesirable for certain applications.
It is well known to employ carbon blacks having higher or lower structure and
surface area to manipulate the performance characteristics of an elastomeric
composition. Carbon blacks of higher surface area and lower structure are
known
to improve crack growth resistance and cut-and-chip resistance as well as,
eenerally,
abrasion resistance, and other performance properties. Commercially available
mixing techniques have been unable to achieve excellent uniformity of
dispersion of
carbon blacks throuQhout the elastomer, however, without unacceptable
degradation
of the natural rubber. In fact, for typical carbon black loading levels in
natural
rubber, such as 45 phr to 75 phr, and oil loading from 0 phr to 10 phr, low
structure
carbon blacks, such as carbon blacks of DBPA less than 110cc/100g,
particularly
those having surface area above about 45m2/g to 65m2/g (CTAB), it has not been
possible to achieve compounds having less than about 1% undispersed carbon
black
(measured as macro-dispersion, as described below) regardless of the duration
and
level of intensity. Furthermore, as noted above, in the highly energy
consumptive
intensive dry mixing methods currently in widespread commercial use, the
mastication
of the elastomer necessary for dispersing such carbon blacks results in
unacceptable
levels of disruption of the polymeric chains of the natural rubber elastomer.
The
resultant reduction in the molecular weiizht of the riatural rubber is
undesirable for
many industrial applications. For use in tire tread, for example, reduced
molecular
weight is known to cause an undesirable increase in the so-called rolling
resistance
of the tire.
Furthermore, while theoretical analysis has indicated desirable improvements
in certain performance characteristics of elastomeric compositions employing
carbon
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blacks of higher surface area and lower structure, it has not been possible
using
known physical milling or other mastication processes to obtain such
elastomeric
compositions in which both the molecular weight of the natural rubber is well
preserved and satisfactory macro-dispersion levels of the carbon black are
achieved.
Generally, it has been found, for example, that the elastomer reinforcing
properties
of a carbon black increase as the particle size of the carbon black decreases.
However, with extremely fine carbon blacks an anomalous condition is known to
be
encountered, in which the expected improvement in properties is not achieved.
This
is understood to be due at least in part to the inability of conventional
elastomer
compoundine methods to adequately disperse the carbon black in the natural
rubber
without undue breakdown of the elastomer polymer. There has been, therefore,
consequent inability to take full advantage of the natural affinity of the
carbon black
and the natural rubber for each other in the case of such carbon blacks.
Since good dispersion of carbon black in natural rubber compounds has been
1~ recoanized for some time as one of the most important objectives for
achieving Qood
quality and consistent product performance, considerable efrort has been
devoted to
the development of procedures for assessing dispersion quality in rubber.
Methods
developed include, e.g. the Cabot Dispersion Chart and various imaQe analvsis
procedures. Dispersion quality can be defined as the state of mixina achieved.
An
ideal dispersion of carbon black is the state in which the carbon black
aQ2lomer ates
(or pellets) are broken down into aagregates (accomplished by dispersive
mixing)
uniformly separated from each other (accomplished by disttibutive mixina),
with the
suriaces of all the carbon black aggretzates completely wetted by the rubber
matrix
(usually referred to as incorporation).
Common problems in the rubber industry which are often related to poor
macro-dispersion can be classified into four major categories: product
performance,
surface defects, surface appearance and dispersion efficiency. The functional
performance and durability of a carbon black-containing rubber formulation,
such as
tensile strenQth, fatigue life and wear resistance, are affected substantially
by macro-
dispersion qualitv. iJndispersed carbon black can also cause surface defects
on
finished products, including visible defects. Eliminating the presence of
surface
defects is of critical impo i-Lance in molded thin parts for functional
reasons and in
extruded profiles for both aesthetic and functional reasons.
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A commercial imaQe analvzer such as the IBAS Compact model imave
analyzer available from Kontron Electronik GmbH (Munich, Germany) can be used
to measure macro-dispersion of carbon black or other filler. Typically, in
quantitative
macro-dispersion tests used in the rubber industry, the critical cut-of-r size
is 10
microns. Defects larger than about 10 microns in size typically consist of
undispersed
black or other filler, as well as any grit or other contaminants, which can
afiect both
visual and functional performance. Thus, measuring macro-dispersion involves
measurins defects on a surface (Qenerated by microtoming, extrusion or
cutting)
greater than 10 microns in size by total area of such defects per unit area
examined
usinQ an imase analysis procedure. Macro-dispersion D(%) is calculated as
follows:
% Undispersed area (%) = 1 n D
m N.
r 4
m
where A,,,= Total sample surface area
examined
N, = Number of defects with size D;
D; = Diameter of circle having the same area as that of the defect
(equivalent circle diameter).
m = number of images
Macro-dispersion of carbon black or other filler in uncured natural rubber or
other suitable elastomer can be assessed usino imaee analysis of cut surface
samples.
Typically, five to ten arbitrarily selected optical images are taken of the
cut surface
for ima2e analvsis. Knife marks and the like preferably are removed usin(y a
numerical filtering technique. Cut surface imaae analysis thus provides
inforr~~ation
regardinb the carbon black dispersion quality inside a natural rubber
compound.
Specifically, percent undispersed area D(%) indicates carbon black macro-
dispersion
quality. As macro-dispersion quality is dearaded, percent undispersed area
increases.
Dispersion quality can be improved, therefore, by reducing the percent
undispersed
area. As noted above, the mixing operations have a direct impact on mixing
efficiency and on macro-dispersion. In izeneral, better carbon black macro-
dispersion
is achieved in the elastomer, for example in a natural rubber masterbatch, by
loneer
mixin- and by more intensive mixing. Unfortunately, however, achievinQ better
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WO 97136724 PCT/US97l05276
macro-dispersion by longer, more intensive mixing, degrades the elastomer into
which the carbon black is beiniz dispersed. This is especially problematic in
the case
of natural rubber, which is hiehly susceptible to mechanical/thermal
dearadation.
Loneer and more intensive mixina, using known mixing techniques and apparatus,
such as a Banbury mixer, reduces the molecular weight of the natural rubber
masterbatch-composition. Thus, improved macro-dispersion of carbon black in
natural rubber is known to be achieved with a corresponding, generally
undesirable
reduction in the molecular weight of the rubber.
In addition to dry mixing techniques, it is known to continuously feed latex
and a carbon black slutry to an agitated coaryulation tank. Such "wet"
techniques are
used commonly with synthetic elastomer, such as SBR. The coagulation tank
contains a coa-aulant such as salt or an aqueous or acid solution typically
having a pH
of about 2.5 to 4. The latex and carbon black slurry are mixed and coaQulated
in the
coagulation tank into small beads (typically a few millimeters in diameter)
referred
to as wet crumb. The crumb and acid effluent are separated, typically by means
of
a vibratinQ shaker screen or the like. The crumb is then dumped into a second
aLyitated tank where it is washed to achieve a neutral or near neutral pH.
Thereafter
the crumb is subjected to additional vibrating screen and drying steps and the
like.
Variations on this method have been susQested for the coaoulation of natural
and
synthetic elastomers. In U.S. patent 4,029,633 to Hagopian et al, which like
the
present invention is assigned to Cabot Corporation, a continuous process for
the
preparation of elastomer tnasterbatch is described. An aqueous slurry of
carbon black
is prepared and mixed with a natural or synthetic elastomer latex. This
mixture
undergoes a so-called creaming operation, optionally using any of various
known
creaming aaents. Following the creaming of the carbon black/latex mixture, it
is
subjected to a coa;ulation step. Specifically, the creamed carbon black/latex
mixture
is introduced as a sinole coherent stream into the core of a stream of
coagulatine
liquor. The solid stream of creamed carbon black/latex mixture is said to
underso
shearinc, and atomi.zing by the stream of coawlatino liquor prior to
coagulation, beina
then passed to a suitable reaction zone for completion of the coagulation.
Following
such coaQulation step, the remainder of the process is substantially
conventional,
involving separation of the crumb from the waste product "serum" and washing
and
drying of the crumb. A somewhat similar process is described in U.S. patent
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3,048,559 to Heller et al. An aqueous slurry of carbon black is continuously
blended
with a stream of natural or synthetic elastomer or latex. The two streams are
mixed
under conditions described as involving violent hydraulic turbulence and
impact. As
in the case of the Hagopian et al patent mentioned above, the combined
strea.*n of
carbon black slurry and elastomer latex is subsequently coaeulated by the
addition of
an acid or salt coamulant solution.
There has long been a need in various industries for elastomeric compounds
of particulate filler dispersed in suitable elastomer, especially, for
example, carbon
black dispersed in natural rubber, having improved macro-dispersion. As
discussed
above, improved macro-dispersion can provide correspondingly improved
aesthetic
and functional characteristics. Especially desirable are new elastomeric
compounds
of carbon black in natural rubber wherein improved macro-dispersion is
achieved
toaether with hiaher molecular weight of the natural rubber. It is an object
of the
present invention to meet some or all of these long felt needs.
Summarv of the Invention
In accordance with a first aspect, a method for preparing elastomer
masterbatch involves feedina simultaneously a particulate filler fluid and an
elastomer
latex fluid to a mixin2 zone of a coa2ulum reactor. A coaeulum zone extends
from
the mixing zone, preferably progressively increasing in cross-sectional area
in the
downstream direction from an entry end to a discharae end. The elastomer latex
mav
be either natural or synthetic and the particulate filler fluid comprises
carbon black
or other particulate filler effective to coagulate the latex. The particulate
filler fluid
is fed to the mixing zone preferably as a continuous, high velocity jet of
injected
fluid, while the latex fluid is fed at low velocity. - The velocitv, flow rate
and
particulate concentration of the particulate filler fluid are sufficient to
cause mixture
with high shear of the latex fluid and flc -urbulence of the mixture within at
least
an upstream portion of the coagulum zone so as to substantially completely
coasulate
the elastomer latex with the paniculate filler prior to the discharge end.
Substantially
complete coagulation can thus be achieved, in accordance with preferred
embodiments, without the need of employinQ an acid or salt coagulation aaent.
In accordance with another aspect, a continuous flow method of producing
elastomer masterbatch comprises the continuous and simultaneous feedine of
latex
4
CA 02511365 2008-06-30
fluid and paniculate filler fluid to the mixing zone of the coasulum reactor
estabGshinQ a continuous, semi-confined flow of a mixture of the elastomer
latex and
particulate filler in the eoagulum zone. Elastomer masterbatch crumb in the
form of
"wonns" or gJobules are discharged from the discharge end of the coagulum
reactor
as a substantiallv constant flow concurrently with the on-going feeding of the
latex
and particulate filler fluid streams into the mixing zone of the coasulum
reactor.
Notably, the plug-type flow and atmospheric or near atmospheric pressure
conditions
at the discharee end of the coagulum reactor are highly advantaeeous in
facilitatinc,
control and collection of the elastomer masterbatch product, such as for
immediate
or subsequent further processing steps.
In accordance with an apparatus aspect, means are provided for feeding
elastomer latex fluid to the mi.dng zone of the aforesaid coaeulum reactor,
preferably
under low pressure, substantially laminar type flow conditions, and means are
provided for simultaneously feeding particulate filler fluid to the mixing
zone under
pressure sufficient to create ajet of sufficient velocity or kinetic energy to
entrain the
elastomer latex as described above, and achieve coagulation before the mixture
flowing downstream from the mixine zone reaches the discharge end of
the'coagulum
reactor. In accordance with cenain preferred embodiments described in detail
below,
means for feeding the elastomer latex fluid and separate means for feeding the
particulate'filler fluid each mav comprise a feed channel in a mix head
inteQral with
a substantially-tubular member defining the coa`ulum zone. The mixing zone may
be provided at the junction of such feed channels within the mix head. In
accordance
with certain prefen-ed embodiments, the mixing zone is simply a coaxial
extension of
the coagulum zone. Progressive increase in the cross-sectional area of the
coawlum
reactor is continuous in certain preferred embodiments and is step-wise in
other
preferred embodiments. Additionally, the coaoulum reactor may be provided with
such optional features as a divener at its discharge end, as further described
below.
Additional optional and preferred features of the apparatus disclosed here for
continuous flow production of elastomer masterbatch are discussed in the
detailed
description below.
7
CA 02511365 2008-06-30
In accordance with one aspect of the present invention, there is provided a
method of
producing elastomer masterbatch, comprising: feeding a continuous flow of
first fluid comprising
elastomer latex to a mixing zone of a coagulum reactor defining an elongate
coagulum zone
extending from the mixing zone to a discharge end; feeding a continuous flow
of second fluid
comprising particulate filler under pressure to the mixing zone of the
coagulum reactor to form a
mixture with the elastomer latex, the mixture passing as a continuous flow to
the discharge end
and the particulate filler being effective to coagulate the elastomer latex,
wherein feeding of the
second fluid against the first fluid within the mixing zone is sufficiently
energetic to substantially
completely coagulate the elastomer latex with the particulate filler prior to
the discharge end; and
discharging a substantially continuous flow of elastomer masterbatch from the
discharge end of
the coagulum reactor.
In accordance with another aspect of the present invention, there is provided
an
apparatus for producing elastomer composite of particulate filler dispersed in
elastomer
comprising: a coagulum reactor defining a mixing zone and an elongate coagulum
zone
extending from the mixing zone to a discharge end; latex feed means for
feeding elastomer latex
fluid continuously to the mixing zone; and filler feed means for feeding
particulate filler fluid as
a continuous jet into the mixing zone to form a mixture with the elastomer
latex fluid traveling
from the mixing zone to the discharge end of the coagulum zone.
In accordance with yet another aspect of the present invention, there is
provided a
continuous flow method of preparing elastomer masterbatch of particulate
filler dispersed in
elastomer, comprising: A) establishing a continuous, semi-confined flow of
combined elastomer
latex and particulate filler under pressure in a coagulum reactor forming an
elongate coagulum
zone extending with progressively increasing cross-sectional area from an
entry end to a
discharge end, by simultaneously (i) feeding elastomer latex fluid
continuously to a mixing zone
at the entry end of the coagulum reactor, and (ii) entraining the elastomer
latex fluid into
particulate filler fluid by feeding the particulate filler fluid as a
continuous jet into the mixing
zone sufficiently energetically against the elastomer latex fluid to
substantially completely
coagulate the elastomer latex with the particulate filler; and B) discharging
from the discharge
end of the coagulum reactor a substantially constant flow of elastomer
masterbatch globules
concurrently with feeding of the fluid streams in accordance with steps A(i)
and A(ii).
7a
CA 02511365 2008-06-30
In accordance with still another aspect of the present invention, there is
provided a
continuous flow method of producing elastomer masterbatch comprising
particulate filler
selected from the group consisting of carbon black, silicon-treated carbon
black, fumed silica,
precipitated silica, and mixtures thereof finely dispersed in natural rubber,
comprising: preparing
a particulate filler fluid by high energy dispersion of the particulate filler
into aqueous liquid in a
homogenizer; and establishing a continuous, semi-confined flow of mixed
natural rubber latex
and particulate filler in a coagulum reactor forming a tubular coagulum zone
extending with
progressively increasing cross-sectional area from an entry end to a discharge
end by
simultaneously (i) feeding a liquid stream of the natural rubber latex at less
than 10 feet per
second continuously to a mixing zone defmed by a mix head in sealed fluid
communication with
the entry end of the coagulum reactor, the mixing zone extending coaxially
with the coagulum
zone, and (ii) entraining the natural rubber latex continuously into the
particulate filler fluid by
feeding the particulate filler fluid into the mixing zone toward the entry end
of the coagulum
zone, through a feed tube substantially coaxial with the coagulum zone, the
particulate filler fluid
exiting the feed tube at a velocity of 200 to 500 feet per second;
simultaneously and continuously
discharging from the discharge end of the coagulum reactor masterbatch
globules in which
coagulation of the natural rubber latex by the particulate filler is
substantially complete; and
simultaneously and continuously drying and pelletizing masterbatch globules
discharged from
the coagulum reactor in a series of dryers.
In accordance with yet still another aspect of the present invention, there is
provided an
elastomer masterbatch comprising elastomer in which particulate filler has
been dispersed by:
feeding a continuous flow of first fluid comprising elastomer latex to a
mixing zone of a
coagulum reactor defining an elongate coagulum zone extending from the mixing
zone to a
discharge end; feeding a continuous flow of second fluid comprising
particulate filler under
pressure to the mixing zone of the coagulum reactor to form a mixture with the
elastomer latex,
the mixture passing as a continuous flow to the discharge end, and the
particulate filler being
effective to coagulate the elastomer latex, wherein mixing of the first fluid
and the second fluid
within the mixing zone is sufficiently energetic to substantially completely
coagulate the
elastomer latex with the particulate filler prior to the discharge end; and
discharging a
substantially continuous flow of elastomer composite from the discharge end of
the coagulum
reactor, the macro-dispersion D(%) of the particulate filler in the elastomer
composite being no
more than 0.2% undispersed area.
7b
CA 02511365 2008-06-30
In accordance with a further aspect of the present invention there is provided
an
elastomer composite comprising particulate filler finely dispersed in
elastomer, formed by a
continuous flow method comprising the steps of: A) establishing a continuous,
semi-confined
flow of mixed elastomer latex and particulate filler under pressure in a
coagulum reactor forming
an elongate coagulum zone extending with progressively increasing cross-
sectional area from an
entry end to a discharge end, by simultaneously (i) feeding elastomer latex
fluid continuously to
a mixing zone at the entry end of the coagulum reactor, and (ii) entraining
the elastomer latex
fluid into particulate filler fluid by feeding the particulate filler fluid as
a continuous jet into the
mixing zone; and B) discharging from the discharge end of the coagulum reactor
a substantially
constant flow of elastomer master batch globules concurrently with feeding of
the fluid streams
in accordance with steps A(i) and A(ii), the macro-dispersion D(%) of the
particulate filler in the
master batch being no more than 0.2% undispersed area.
In accordance with yet a further aspect of the present invention, there is
provided an
apparatus for producing elastomer composite of particulate filler dispersed in
elastomer,
comprising: a coagulum reactor forming an elongate coagulum zone extending
with
progressively increasing cross-sectional area from an entry end to a discharge
end; means for
feeding elastomer latex fluid continuously to a mixing zone at the entry end
of the coagulum
reactor; and means for feeding to the mixing zone a continuous jet of
particulate filler fluid
effective to entrain elastomer latex fluid into.an mixture with the
particulate filler fluid and to
substantially completely coagulate the elastomer latex with the particulate
filler prior to the
mixture arriving at the discharge end.
In accordance with yet another aspect, elastomer composites are provided as
product of
the process or apparatus disclosed above. In accordance with preferred
embodiments, novel
elastomer composites are provided having macro-dispersion
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level of the particulate filler, molecular weiEiht of the elastomer,
parriculate loading
level, choice of particulate filler (includin-, for example, carbon black
fillers of
exceptionally high surface area and low structure) and/or other
characteristics not
previously achieved. In that regard, the methods and apparatus disclosed here
can
achieve excellent macro-dispersion, even of certain fillers, such as carbon
blacks
havina a structure to surface area ratio DBP:CTAB less than 1.2 and even less
than
1, in elastomers such as natural rubber, with little or no detrradation of the
molecular
weight of the elastomer. In accordance with yet other aspects of the
invention,
intermediate products are provided as well as final products which are formed
of the
elastomer composites produced by the method or apparatus disclosed here.
Bv virtue of the method and apparatus disclosed here, elastomer masterbatch
can be produced in a continuous flow process involvinQ mixture of elastomer
latex
and particulate filler fluids at turbulence levels and flow control conditions
sufficient
to achieve coagulation even without use of traditional coasulatina aaents. In
fact,
it will be immediatel_y recognized to be of ereat commercial benefit that
elastomer
masterbatch crumb is achieved, that is, coaaulated latex is achieved, here
without the
nerd for either intensive dry mastication of elastomer with filler or exposing
a liquid
latex/particulate composition to a stream or tank of coagulant. Thus, in
routine
commercial implementation the cost and complexity of employing acid
coagulation
solutions can be avoided. Prior techniques involving premixing of latex and
particulate, such as in the above-mentioned Heller et al patent and Hasopian
et al
patent do not even recoLrnize the possibility of achieving coasulation without
exposing the latex/particulate mixture to the usual coagulant solution with
its
attendant cost and waste disposal disadvantages.
Feed rates of latex fluid and particulate filler fluid to the mixing zone of
the
coagulum reactor can be precisely metered to achieve high yield rates, with
little free
latex and little undispersed filler in the product crumb at the discharae end
of the
coawlum reactor. Without wishing to be bound by theory, it presently is
understood
that a quasi-mono-phase svstem is established in the mixing zone except that
coaeulum soIids are beinQ formed there and/or downstream thereof in the
coaoulum
zone. Extremely high feed velocity of the particulate filler fluid into the
mixing zone
of the coasulum reactor and velocity differential relative the latex fluid
feed are
believed to be significant in achieving sufficient turbulence, i.e.,
sufficiently energetic
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CA 02511365 1997-03-25
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shear of the latex by the impact of the particulate filler fluid jet for
thorough mixincy
and dispersion of the particulate into the latex fluid and coasulation. High
mixinc,
energies yield product masterbatch crumb with excellent dispersion, together
with
controlled product delivery. The coagulum is created and then formed into a
desirable extrudate.
In accordance with another aspect, novel elastomer composites are provided,
comprisina a particulate filler dispersed in natural rubber, the macro-
dispersion level
of the filler in the elastomer composite being less than about 0.2%
undispersed area,
preferably less than about 0.1% undispersed area. Consistent with the
discussion
above, macro-dispersion here means the macro-dispersion D(%) of the carbon
black
measured as percent undispersed area for defects larger than 10 microns. In
natural
rubber masterbatch and other elastomer composites disclosed here, the
molecular
weight of the natural rubber, that is, the MW,o, (weight averaae) of the sol
portion,
preferably is at least about 300,000, more preferabiy at least about 400,000,
beina in
certain preferred embodiments between 400,000 and 900,000. The elastomer
composites optionally comprise extender oil, such as about 0 to 20 phr, more
preferably about 0 to 10 phr extender oil, and/or other ingredients such as
are well
known for optional use in compounding natural rubber with carbon black filler.
As
discussed further below in connection with certain preferred and exemplary
embodiments, the novel elastomer composites disclosed here can provide hiahlv
desirable phvsical properties and performance characteristics. Accordingly,
the
invention presents a sianincant technological advance.
In accordance with another aspect, novel elastomer composites are provided
in which there is a novel, heretofore unobtained, combination of properties,
including
certain macro-dispersion level of the carbon black filler, molecular weight of
the
natural rubber, carbon black loading level, carbon black characteristics
(includinQ
surface area and structure, e.s., carbon black fillers of exceptionally high
surface area
and low structure) and/or other characteristics. In accordance with various
aspects
of the invention, masterbatch compositions and intermediate products are
provided,
as well as final products which are formed of them.
These and other aspects and advantages of various embodiments of the
invention will be further understood in view of the following detailed
discussion of
certain preferred embodiments. 9
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Brief Descrintion of the Drawings
The following discussion of certain preferred embodiments will make
reference to the appended drawinas wherein:
Fig. I is a schematic flow chart illustration of the apparatus and method for
preparing elastomer masterbatch in accordance with certain preferred
embodiments;
Fie. 2 is an elevation view, partly schematic, of a preferred embodiment
consistent with the schematic flow chart illustration of Fig. 1;
Fie. 3 is an elevation view, partially schematic, of an alternative preferred
embodiment consistent with the schematic flow chart illustration of Fig. 1;
Fig, 4 is an elevation view, partially in section, of the mix head/coaeulum
reactor assembly of the embodiment of Fig. 3;
Fig. 5 is an elevation view, partially in section, corresponding to the view
of
Fio. 4, illustratina an alternative preferred embodiment;
Fia. 6 is a section view taken through line 6-6 of Fig. 5;
Fis. 7 is a section view of a mix head suitable for use in an alternative
preferred embodiment;
Fig. 8 is a Qraph showing the surface area and structure properties (CTAB
and DBPA) of carbon blacks emploved in certain hiehly preferred masterbatch
compositions in accordance with the present invention;
Fias. 9 - 25 are oraphs showing the macro-dispersion, natural rubber
molecular weisht and/or other characteristics of novel elastomer composites in
accordance with this invention comprising carbon blacks shown in Fig. 8, in
some
cases alonQ with data relating to control samples for comparison, exemplifyino
the
siQnificant improvements in physical characteristics and performance
properties
achieved by the elastomer composites; -
Fias. 26 - 29 are zraphs showins morpholoQical properties of carbon blacks,
i"e., structure (DBPA) and surface area (CTAB), and identifying reaions or
zones of
carbon blacks (by such morphological propenies) which are suitable for
specific
product applications; and
Figs. 30 and 31 are araphs showine the macro-dispersion and natural rubber
molecular weight of novel elastomer composites in accordance with this
invention,
along with control samples for comparison.
CA 02511365 1997-03-25
WO 97/3671.4 PCT/L'S97/05276
It should be understood that the appended drawings are not necessarily
precisely to scale. Certain features may have been enlarged or reduced for
convenience or clarity of illustration. Directional references used in the
following
discussion are based on the orientation of components illustrated in the
drawings
unless otherwise stated or otherwise clear from the context. In general,
apparatus in
accordance with different embodiments of the invention can be employed in
various
arTangements. It will be within the ability of those skilled in the art, given
the benent
of the present disclosure, to determine appropriate dimensions and
orientations for
apparatus of the invention employing routine technical skills and taking into
account
well-known factors particular to the intended application, such as desired
production
volumes, material selection, duty cycle, and the like. Reference numbers used
in one
drawine mav be used in -other drawinas for the same feature or element.
Detailed Descrintion of Certain Preferred Embodiments
By vinue of the method and apparatus disclosed here, elastomer masterbatch
can be produced in a continuous flow process involving mixture of elastomer
latex
and particulate filler fluids at turbulence levels and flow control conditions
sufficient
to achieve coagulation even without use of traditional coagulating agents. In
fact,
it will be immediately recognized to be of great commercial benefit that
elastomer
masterbatch crumb is achieved, that is, coavntlated latex is achieved, here
without the
need for either intensive dry mastication of elastomer with filler or exposing
a liquid
latex/par -Liculate composition to a stream or tank of coagulant. Thus, in
routine
commercial implementation the cost and complexity of employing acid
coagulation
solutions can be avoided. Prior techniques involving premixing of latex and
_particulate, such as in the above-mentioned Heller et a] patent and Hagopian
et al
patent do not even recognize the possibility of achievina coagulation without
exposing the latex/particulate mixture to the usual coaoulant solution with
its
attendant cost and waste disposal disadvantages.
Feed rates of latex fluid and particulate filler fluid to the mixing zone of
the
coaaulum reactor can be precisely metered to achieve high yield rates, with
little free
latex and little undispersed filler in the product crumb at the discharge end
of the
coao-,ulum reactor. Without wishine to be bound by theory, it presently is
understood
that a quasi-mono-phase system is established in the mixing zone except that
II
CA 02511365 1997-03-25
WO 97/36724 PCT/IIS97/05276
coaculum solids are beinQ formed there and/or downstream thereof in the coa--
ulum
zone. Extremely high feed velocity of the particulate filler fluid into the
mixine zone
of the coagulum reactor and velocity differential relative the latex fluid
feed are
believed to be sienificant in achieving sufficient turbulence, i.e.,
sufficiently energetic
shear of the latex by the impact of the particulate filler fluid jet for
thorough mixing
and dispersion of the particulate into the latex fluid and coagulation. Hish
mixing
enereies yield product masterbatch crumb with excellent dispersion, together
with
controlled product delivery. The coaeulum is created and then formed into a
desirable extrudate.
Certain preferred embodiments are discussed below, of methods and
apparatus for producincr the novel elastomer composites disclosed here. VJhile
various preferred embodiments of the invention can employ a variety of
different
fillers and elastomers, certain portions of the foIlowina detailed description
of method
and apparatus aspects of the invention will, in some instances, for
convenience,
describe their use primarily in producing masterbatch comprising natural
rubber and
carbon black. It will be within the ability of those skilled in the art, siven
the benefit
of this disclosure, to employ the method and apparatus disclosed here in
accordance
with the principles of operation discussed below to produce masterbatch
comprisinc,
a number of altemative or additional elastomers, fillers and other materials.
In brief,
such methods for preparins elastomer masterbatch involve feeding
simultaneously a
slurry of carbon black or other filler and a natural rubber latex fluid or
other suitable
elastomer fluid to a mixino zone of a coacaulum reactor. A coaQulum zone
extends
from the mixinQ zone, preferably progressively increasing in cross-sectional
area in
the downstream direction from an entry end to a discharge end. The slurry is
fed to
the mixing zone preferably as a continuous, high velocity iet of injected
fluid, while
the natural rubber latex fluid is fed at relatively low velocity. The high
velocity, flow
rate and particulate concentration of the fille 'urry are sufficient to cause
mixture
and hish shear of the latex fluid, flow turbulence of the nuxture within at
least an
upstream portion of the coagulum zone, and substantially completely coagulate
the
elastomer latex prior to the discharp-e end. Substantially complete
coagulation can
thus be achieved, in accordance with preferred embodiments, without the need
of
employing an acid or salt coagulation agent. The preferred continuous flow
method
of producino the elastomer composites comprises the continuous and
simultaneous
P-
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WO 97/36724 PCT/L'S9 7/05276
feedine of the latex fluid and filler slurry to the mixing zone of the
coagulum reactor,
establishing a continuous, semi-confined flow of a mixture of the latex and
filler slurry
in the coa2ulum zone. Elastomer composite crumb in the form of "worms" or
globules are discharged from the discharae end of the coaguulum reactor as a
substantially constant flow concurrently with the on-going feeding of the
latex and
carbon black sluny streams into the mixing zone of the coagulum reactor.
Notably,
the plug-type flow and atmospheric or near atmospheric pressure conditions at
the
discharse end of the coasulum reactor are highly advantageous in facilitating
control
and collection of the elastomer composite product, such as for immediate or
] 0 subsequent further processing steps. Feed rates of the natural rubber
latex fluid and
carbon black slurry to the mixing zone of the coaeulum reactor can be
precisely
metered to achieve high yield rates, with little free latex and little
undispersed carbon
black in the product crumb at the discharge end of the coa`ulum reactor.
Without
wishing to be bound by theory, it presently is understood that a quasi-mono-
phase
svstem is established in the mixing zone except that coaaulum solids are being
formed
there and/or downstream thereof in the coawlum zone. Extremely hiah feed
velocity of the carbon black slurry into the mixing zone of the coaaulum
reactor and
velocity differential relative the natural rubber latex fluid feed are
believed to be
siQnificant in achievine sufficient turbulence, i.e., sufficiently energetic
shear of the
latex by the impact of the paniculate filler fluid jet for thorough mixing and
dispersion
of the particulate into the latex fluid and coagulation. High mixins eneraies
yield the
novel product with excellent macro-dispersion, toQether with controlled
product
delivery. The coawlum is created and then formed into a desirable extrudate.
The aforesaid prefe:red apparatus and techruques for producing the elastomer
composites disclosed here are discussed in conjunction with the appended
drawings,
wherein a continuous flow method of producing elastomer masterbatch employs a
continuous, semi-confined flow of elastomer latex, for example, natural rubber
latex
(field latex or concentrate) mixed with a filler slurry, for example, an
aqueous slurry
of carbon black, in a coagulum reactor forming an elongate coagulum zone which
extends, preferably with prooressively increasing cross-sectional area, from
an entry
end to a discharge end. The term "semi-confined" flow refers to a hiehly
advantaoeous feature. As used here the term is intended to mean that the flow
path
followed by the mixed latex fluid and filler slurry within the coavulum
reactor is
CA 02511365 1997-03-25
WO 97136 724 PCT/US97/05276
closed or substantially closed upstream of the mixing zone and is open at the
opposite, downstream end of the coaeulum reactor, that is, at the dischar(ye
end of
the coagulum reactor. Turbulence conditions in the upstream portion of the
coagulum zone are maintained in on-goincy, at least quasi-steady state fashion
concurrently with substantially plug flow-type conditions at the open
discharge end
of the coagulum reactor. The discharge end is "open" at least in the sense
that it
permits discharge of coagulum, eenerally at or near atmospheric pressure and,
typically, by simple graviry drop (optionaliy within a shrouded or screened
flow path)
into suitable collection means, such as the feed hopper of a de-watering
extruder.
Thus, the semi-confined flow results in a turbulence sradient extending
axially or
lonritudinally within at least a portion of the coagulum reactor. Without
wishing to
be bound by theory, it presently is understood that the coagulum zone is
siiznificant
in permittina hivh turbulence mixing and coaaulation in an upstream portion of
the
coaEzulum reactor, tosether with substantially plug-type discharge flow of a
solid
product at the discharge end. Injection of the carbon black or other filler
slurry as a
continuous jet into the mixino zone occurs in on-going fashion simultaneously
with
ease of collection of the elastomer masterbatch crumb discharaed under
substantially
plua-type flow conditions and Lyenerally ambient pressure at the discharge end
of the
coaeulum reactor. Similarly, axial velocities of the slurry through the slurry
nozzle
into the mixinQ zone and, typically, at the upstream end of the coaQulum zone
are
substantially hiEher than at the dischar?e end. Axial velocity of the slurry
will
typically be several hundred feet per second as it enters the mixing zone,
preferably
from a small bore, axially oriented feed tube in accordance with preferred
embodiments discussed below. The axial velocity of the resultant flow at the
entry
end of a coac-,ulum reactor with expanding cross-sectional area in a typical
application
may be, for example, 5 to 20 feet per second, and more usually 7 to 15 feet
per
second. At the dischar2e end, ir -ontrast again, axial velocity of the
masterbatch
crumb product being dischareed : e will in a typical application be
approximately
I to 10 feet per second, and more aenerally 2 to 5 feet per second. Thus, the
aforesaid semi-confined turbulent flow achieves the hiehly significant
advantage that
natural rubber or other elastomer latex is coaaulated by mixture with carbon
black
or other filler even in the absence of subsequent treatment in a stream or
tank of acid,
iy
CA 02511365 1997-03-25
WO 97/36724 PCT/L;S97/05276
salt or other coasulant solution, with controlled, preferably quasi-molded
product
delivery from the coagulum reactor for subsequent processing.
It should be understood in this regard that reference to the coagulum reactor
as being "open" at the discharge end is not intended to mean that the
discharge end
is necessarily exposed to view or easily accessed by hand. It may instead be
permanently or releasably attached to a collection device or subsequent
processing
device, such as a diverter (discussed further below), dryer, etc. The
discharge end
of the coaoulum reactor is open in the important sense that the turbulent flow
within
the coa--ulum zone of the coaoulum reactor, which is under high pressure and
sealed
against any significant rearward (i.e., upstream) travel at the mixing zone,
is
pernutted to establish the aforesaid pressure and/or velocity gradient as it
travels
toward and exits from the discharae end.
It should also be recos-nized in this resard that the turbulence of the flow
lessens alone the coaoulum reactor toward the discharae end. Substantial plug
flow
of a solid product is achieved prior to the discharae end, dependent upon such
factors
as percent of capaciry utilization, selection of materials and the like.
Reference here
to the flow being substantially plug flow at or before the discharge end of
the
coagulum reactor should be understood in light of the fact that the flow at
the
discharge end is composed primarily or entirely of masterbatch crumb, that is,
globules or "worms" of coagulated elastomer masterbatch. The crumb is
typically
quasi-molded to the inside shape of the coagulum zone at the point along the
coagulum zone at which flow became substantially plug flow. The ever-advancing
mass of "worms" or globules advantageously have plug-type flow in the sense
that
they are traveling generally or primarily axially toward the discharge end and
at any
point in time in a given cross-section of the coaaulum zone near the discharge
end
have a fairly uniiorm velocity, such that they are readily collected and
controlled for
further processing. Thus, the fluid phase mixing aspect disclosed here can
advantaQeously be carried out at steady state or quasi-steady state
conditions,
resulting in high levels of product uniformity.
A preferred embodiment of the method and apparatus disclosed here is
illustrated schematically in Fig. 1. Those skilled in the art will recognize
that the
various aspects of svstem configuration, component selection and the like will
depend
to some extent on the particular characteristics of the intended application.
Thus, for
CA 02511365 1997-03-25
WO 97136724 PCT/US97/05276
example, such factors as maximum system throu;h-put capacity and material
selection flexibility will influence the size and layout of system components.
In
general, such considerations will be well within the ability of those sl:illed
in the art
given the benefit of the present disclosure. The system illustrated in Fia. I
is seen to
include means for feeding natural rubber latex or other elastomer latex fluid
at low
pressure and low velocity continuously to a mixing zone of a coasulum reactor.
More particularly, a latex pressure tank 10 is shown, to hold the feed supply
of latex
under pressure. Alternatively, a latex storaae tank can be used, equipped with
a
peristaltic pump or series of pumps or other suitable feed means adapted to
hold
elastomer latex fluid to be fed via feed line 12 to a mixing zone of a
coagulum reactor
14. Latex fluid in tank 10 may be held under air or nitrosen pressure or the
like, such
that the latex fluid is fed to the mixing zone at a line pressure of
preferably less than
10 psig, more preferably about 2 - 8 psig, and tvpically about 5 psig. The
latex feed
pressure and the flow lines, connections, etc., of the latex feed means should
be
arranaed to cause shear in the flowinLy latex fluid as low as reasonably
possible.
Preferably all flow lines, for example, are smooth, with only larae radius
turns, if any,
and smooth or faired line-to-line interconnections. The pressure is selected
to yield
the desired flow velocity into the mixinc, zone; an example of a usefiul flow
velocity
is no more than about 12 feet per second.
Suitable elastomer latex fluids include both natural and synthetic elastomer
latices and latex blends. The late.x must, of course, be suitable for
coaQulation by the
selected particulate filler and must be suitable for the intended purpose or
application
of the final rubber product. It will be within the ability of those skilled in
the art to
select suitable elastomer latex or a suitable blend of elastomer latices for
use in the
methods and apparatus disclosed- here, eiven the benefit of this disclosure.
Exemplary elastomers include, but are not limited to, rubbers, polymers (e.a.,
homopolymers, copol,vmers and/or terpolymers) of 1,3-butadiene, styrene,
isoprene,
isobutylene, 2,3-dimethyl-1,3-butadiene, acrylonitrile, ethylene, and
propylene and
the Iil:e. The elastomer may have a gtass transition temperature (Tg) as
measurea by
differential scanning calorimetry (DSC) ranging from about -120 C to about 0
C.
Examples include, but are not limited to, styrene-butadiene rubber (SBR),
natural
rubber and its derivatives such as chlorinated rubber, polybutadiene,
polyisoprene,
poly(stryene-co-butadiene) and the oil extended derivatives of any of them.
Blends
~V
CA 02511365 1997-03-25
WO 977136724 PCT/US97/05276
of any of the foregoing may also be used. The latex may be in an aqueous
carrier
liquid. Altematively, the liquid carrier may be a hydrocarbon solvent. In any
event,
the elastomer latex fluid must be suitable for controlled continuous feed at
appropriate velocity, pressure and concentration into the mixin2 zone.
Particular
5- suitable synthetic rubbers include: copolymers of from about 10 to about 70
percent
by weight of styrene and from about 90 to about 30 percent by weight of
butadiene
such as copolymer of 19 parts styrene and 81 parts butadiene, a copolymer of
30
parts styrene and 70 parts butadiene, a copolymer of 43 parts styrene and 57
parts
butadiene and a copolymer of 50 parts stvrene and 50 parts butadiene; polymers
and
copolvmers of conjueated dienes such as polybutadiene, polvisoprene,
polvchloroprene, and the like, and copolymers of such conjugated dienes with
an
ethvlenic Qroup-containing monomer copolymerizable therewith such as stvrene,
methvl styrene, chlorostyrene, acrvlonitrile, 2-vinyl-pyridine, 5-methvl-2-
vinvipyridine, 5-ethyl-2-vinylpyri dine, 2-methyl-5-vinylpyridine, alkyl-
substituted
acrylates, vinyl ketone, methyl isopropenyl ketone, methyl vinyl either,
aiphamethylene carboxylic acids and the esters and anudes thereof such as
acrylic acid
and dialkylacrvlic acid amide. Also suitable for use herein are copolymers of
ethylene
and other high alpha olefins such as propylene, butene-1 and pentene-1. As
noted
further below, the rubber compositions of the present invention can contain,
in
addition to the elastomer and filler, curina aQents, a couplina aLyent, and
optionally,
various processino aids, oil extenders and antidegradents.
In that reaard, it should be understood that the elastomer composites
disclosed here include vulcanized compositions (VR), thermoplastic
vulcanizates
(TPV), thermoplastic elastomers (TPE) and thermoplastic polyolefins (TPO).
TPV,
TPE, and TPO materials are further classified by their ability to be extruded
and
molded several times without loss of performance characteristics. Thus, in
making
the elastomer composites one or more curing aQents such as, for example,
sulfur,
sulfur donors, activators, accelerators, peroxides, and other systems used to
effect
vulcanization of the elastomer composition may be used.
Where the elastomer latex comprises natural rubber latex, the natural rubber
latex can comprise field latex or latex concentrate (produced, for example, by
evaporation, centrifueation or creaming). The natural rubber latex must, of
course,
be suitable for coam.tlation by the carbon black. The latex is provided
typically in an
1"1
CA 02511365 1997-03-25
WO 97/36724 PCT/CTS97/05276
aqueous carrier liquid. Alternatively, the liquid carrier may be a hydrocarbon
solvent.
In any event, the natural rubber latex fluid must be suitable for controlled
continuous
feed at appropriate velocity, pressure and concentration into the mixing zone.
The
well known instability of natural rubber latex is advantageously accommodated,
in
that it is subjected to relatively low pressure and low shear throughout the
system
until it is entrained into the aforesaid semi-confined turbulent flow upon
encountering
the extraordinarily high velocity and kinetic energy of the carbon black
slurry in the
mixing zone. In certain preferred embodiments, for example, the natural rubber
is fed
to the mixing zone at a pressure of about 5 psig, at a feed velocity in the
range of
about 3 - 12 ft. per second, more preferably about 4 - 6 ft. per second.
Selection of
a suitable latex or blend of latices will be well within the ability of those
skilled in the
art given the benefit of the present disclosure and the knowledge of selection
criteria
generally well recognized in the industry.
The particulate filler fluid, for example, carbon black slurry, is fed to the
nuxing zone at the entry end of coaeulum reactor 14 via feed line 16. The
slurry may
comprise any suitable filler in a suitable carrier fluid. Selection of the
carrier fluid will
depend largely upon the choice of particulate filler and upon system
parameters.
Both aqueous and non-aqueous liquids may be used, with water being preferred
in
many embodiments in view of its cost, availability and suitability of use in
the
production of carbon black and certain other filler slurries.
When a carbon black filler is used, selection of the carbon black will depend
largely upon the intended use of the elastomer masterbatch product.
Optionally, the
carbon black filler can include also any material which can be slurried and
fed to the
mixing zone in accordance with the principles disclosed here. Suitable
additional
particulate fillers include, for example, conductive fillers, reinforcing
fillers, fillers
comprising short fibers (typically having an LID aspect ratio less than 40),
flakes, etc.
Thus, exemplary particulate fillers which can be employed in producing
elastomer
masterbatch in accordance with the methods and apparatus disclosed here, are
carbon
black, fumed silica, precipitated silica, coated carbon black, chemically
functionalized
carbon blacks, such as those having attached or¾anic groups, and silicon-
treated
carbon black, either alone or in combination with each other. Suitable
chemically
functionalized carbon blacks include those disclosed in International
Application No.
PCT/US95/16194 (W09618688),
l 8'
CA 02511365 1997-03-25
WO 97/36724 PCT/liS97105276
In silicon-treated carbon black, a silicon containing species such as an
oxide or carbide of silicon, is distributed through at least a portion of the
carbon
black aggregate as an intrinsic part of the carbon black. Conventional carbon
blacks
exist in the form of aggre.gates, with each aggregate consisting of a single
phase,
which is carbon. This phase may exist in the form of a graphitic crystallite
and/or
amorphous carbon, and is usually a mixture of the two forms. As discussed
elsewhere herein, carbon black aggregates may be modified by depositing
silicon-
containing species, such as silica, on at least a portion of the surface of
the carbon
black aQgregates. The result may be described as silicon-coated carbon blacks.
The
materials described herein as silicon-treated carbon blacks are not carbon
black
aggrezates which have been coated or otherwise modified, but actually
represent a
different kind of aagregate. In the silicon-treated carbon blacks, the
aggreQates
contain two phases. One phase is carbon, which will still be present as
graphitic
crystallite and/or amorphous carbon, while the second phase is silica (and
possibly
other silicon-containing species). Thus, the silicon-containing species phase
of the
silicon-treated carbon black is an intrinsic part of the aagregate; it is
distributed
throughout at least a portion of the agaregate. It will be appreciated that
the
multiphase aggregates are quite different from the silica-coated carbon blacks
mentioned above, wluch consist of pre-formed, single phase carbon black
agQregates
having silicon-containing species deposited on their surface. Such carbon
blacks may
be surface-treated in order to place a silica functionality on the surface of
the carbon
black aggregate. In this process, an existing aggregate is treated so as to
deposit or
coat silica (as well as possibly other silicon-containing species) on at least
a portion
of the surface of the aggreoate. For example, an aqueous sodium silicate
solution
may be used to deposit amorphous silica on the surface of carbon black
aggregates
in an aqueous slurry at high pH, such as 6 or higher, as discussed in Japanese
Unexamined Laid-Open (Kokai) Publication No. 63-63755. More specifically,
carbon black may be dispersed in water to obtain an aqueous slurry consisting,
for
example, of about 5% by weiaht carbon black and 95% by weight water. The
slurry
is heated to above about 70 C, such as to 85-95 C, and the pH adjusted to
above 6,
such as to a range of 10-11, with an alkali solution. A separate preparation
is made
of sodium silicate solution, containing the amount of silica which is desired
to be
deposited on the carbon black, and an acid solution to bring the sodium
silicate
Iq
CA 02511365 1997-03-25
WO 97/36724 PCT/L'S97/05276
solution to a neutral pH. The sodium siiicate and acid solutions are added
dropwise
to the slurry, which is maintained at its starting pH value with acid or
alkali solution
as appropriate. The temperature of the solution is also maintained. A
suilgested rate
for addition of the sodium silicate solution is to calibrate the dropwise
addition to add
about 3 weight percent silicic acid, with respect to the total amount of
carbon black,
per hour. The slurry should be stirred during the addition, and after its
completion
for from several minutes (such as 30) to a few hours (i.e., 2-3). In contrast,
silicon-
treated carbon blacks may be obtained by manufacturing carbon black in the
presence
of volatizable silicon-containing compounds. Such carbon blacks are preferably
produced in a modular or "staaed" furnace carbon black reactor having a
combustion
zone followed by a zone of converging diameter, a feed stock injection zone
with
restricted diameter, and a reaction zone. A quench zone is located downstream
of
the reaction zone. Typically, a quenching fluid, oenerally water, is sprayed
into the
stream of newly formed carbon black particles flowing from the reaction zone.
In
producinQ silicon-treated carbon black, the aforesaid volatizable silicon-
containintr
compound is introduced into the carbon black reactor at a point upstream of
the
quench zone. Useful compounds are volatizable compounds at carbon black
reactor
temperatures. Examples include, but are not limited to, silicates such as
tetraethoxy
orthosilicate (TEDS) and tetramethoxy orthosilicate, silanes such as,
tetrachloro
silane, and trichloro methvlsilane; and colatile silicone polymers such as
octamethylcyclotetrasiloxane (OMTS). The fiow rate of the volatilizable
compound
will determine the weight percent of silicon in the treated carbon black. The
weiQht
percent of silicon in the treated carbon black typically ranizes from about
0.1 percent
to 25 percent, preferably about 0.5 percent to about 10 percent, and more
preferably
about 2 percent to about 6 percent. The volatizable compound may be pre-mixed
with the carbon black-formin2 feed stock and introduced with the feed stock
into the
reaction zone. Alternatively, the volatizable compound may be introduced to
the
reaction zone separately, either upstream or downstream from the feed stock
injection point.
As noted above, additives may be used, and in this regard coupling asents
useful for couplin; silica or carbon black should be expected to be usefui
with the
silicon-treated carbon blacks. Carbon blacks and numerous additional suitable
particulate fillers are commercially available and are known to those skilled
in the art.
ZD
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Selection of the particulate filler or mixture of particulate fillers will
depend
largely upon the intended use of the elastomer masterbatch product. As used
here,
particulate filler can include any material which can be slurried and fed to
the mixins
zone in accordance with the principles disclosed here. Suitable particulate
fillers
5. include, for example, conductive fillers, reinforcing fillers, fillers
comprising short
fibers (typically having an L/D aspect ratio less than 40), flakes, etc. In
addition to
the carbon black and silica-type fillers mentioned above, fillers can be
formed of clay,
glass, polymer, such as aramid fiber, etc. It will be within the ability of
those skilled
in the art to select suitable particulate fillers for use in the method and
apparatus
disclosed here given the benefit of the present disclosure, and it is expected
that any
filler suitable for use in elastomer compositions may be incorporated into the
elastomer composites using the teachings of the present disclosure. Of course,
blends
of the various particulate fillers discussed herein may also be used.
Preferred embodiments of the invention consistent with Fig. I are especially
well adapted to preparation of paniculate filler fluid comprising aqueous
slurries of
carbon black. In accordance with known principles, it will be understood that
carbon
blacks havino lower surface area per unit weiaht must be used in higher
concentration
in the particulate siurry to achieve the same coaaulation efficacy as lower
concentrations of carbon black havin- higher surface area per unit weight.
Aeitated
mixing tank 18 receives water and carbon black, e.o., optionally pelletized
carbon
black, to prepare an initial mixture fluid. Such mixture fluid passes through
discharge port 20 into fluid line 22 equipped with pumping- means 24, such as
a
diaphragm pump or the like. Line 28 passes the mixture fluid to colloid mill
32, or
altenlatively a pipline grinder or the like, through intake port 30. The
carbon black
is dispersed in the aqueous carrier liquid to form a dispersion fluid which is
passed
throuQh outlet port 31 and fluid line 33 to a homogenizer 34. Pumping means
36,
preferably comprising a progressing cavity pump or the like is provided in
line 33.
Homoeenizer 34 more finely disperses the carbon black in the carrier liquid to
form
the carbon black slurry which is fed to the mixing zone of the coaeulum
reactor 14.
It has an inlet port 37 in fluid communication with line 33 from the colloid
mill 32.
The homogenizer 34 may preferably comprise, for example, a Microfluidizer
system
commercially available from Microfluidics International Corporation (Newton,
Massachusetts, USA). Also suitable are homogenizers such as models MS 18, MS45
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CA 02511365 1997-03-25
WO 97136724 PCT/US97/05276
and MC120 Series homogenizers available from the APV Homoaenizer Division of
APV Gaulin, Inc. (Wilmineton, Massachusetts, USA). Other suitable homogenizers
are commercially available and will be apparent to those skilled in the art
given the
benefit of the present disclosure. Typically, carbon black in water prepared
in
~ accordance with the above described system will have at least about 90%
agQlomerates less than about 30 microns, more preferably at least about 90%
aeglomerates less than about 20 microns in size. Preferably, the carbon black
is
broken down to an averap-e size of 5 - 15 microns, e.g., about 9 microns. Exit
port
38 passes the carbon black slurry from the homogenizer to the mixing zone
through
._._.: 10 feed line 16_ The slurry'may reach 10,000 to 15,000 psi in the
homogenizer step and
exit the homoainizer at about 600 psi or more. Preferably, a hish carbon black
content is used to reduce the task of removing excess water or other carrier.
Typically, about 10 to 30 weiszht percent carbon black is preferred. Those
skilled in
the art will recoenize, given the benefit of this disclosure, that the carbon
black
15 content (in weiaht percent) of the slurry and the slurry flow rate to the
mixing zone
should be coordinated with the natural rubber latex flow rate to the mixing
zone to
achieve a desired carbon black content (in phr) in the masterbatch. The carbon
black
content will be selected in accordance with known principles to achieve
material
characteristics and performance properties suited to the intended application
of the
20 product. Typically, for example, carbon blacks of CTAB value 10 or more are
used
in sufficient amount to achieve carbon black content in the masterbatch of at
least
about 30 phr.
The slurry preierably is used in masterbatch production immediately upon
being prepared. Fluid conduits carrying the slurry and any optional holding
tanks and
- 25 the like, should establish or maintain conditions which substantially
preserve the
dispersion of the carbon black in the slurry. That is, substantial
reaglomeration or
settling out of the particulate filler in the slurry should be prevented or
reduced to the
extent reasonably practical. Preferably all flow lines, for example, are
smooth, with
smooth line-to-line interconnections. Optionally, an accumulator is used
between the
30 homogenizer and the mixing zone to reduce fluctuations in pressure or
velocity of the
slurry at the slurry nozzle tip in the mixing zone.
Natural rubber latex fluid or other elastomer latex fluid passed to the mixing
zone via feed line 12 and carbon black slurry fed to the mixinc, zone via feed
line 16
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under proper process parameters as discussed above, can produce a novel
elastomer
composite, specifically, elastomer masterbatch crumb. Means may also be
provided
for incorporating various additives into the elastomer masterbatch. An
additive fluid
comprising one or more additives may be fed to the mixing zone as a separate
feed
5. stream. One or more additives also may be pre-mixed, if suitable, with the
carbon
black sluny or, more typically, with the elastomer latex fluid. Additives also
can be
mixed into the masterbatch subsequently, e.g., by dry mixing techniques.
Numerous
additives are well known to those skilled in the art and include, for example,
antioxidants, antiozonants, plasticizers, processina aids (e.g., liquid
polymers, oils and
the like), resins, flame-retardants, extender oils, lubricants, and a mixture
of any of
them. The seneral use and selection of such additives is well known to those
skilled
in the art. Their use in the system disclosed here will be readily understood
with the
benefit of the present disclosure. In accordance with certain alternative
embodiments,
curative also can be incorporated in like manner, to produce a curable
elastomer
composite which may be referred to as a curable base compound.
The mixing zone/coar~ulum zone assembly is discussed in more detail below.
The elastomer masterbatch crumb is passed from the discharize end of coagulum
reactor 14 to suitable drying apparatus. In the preferred embodiment of Fig. I
the
masterbatch crumb undergoes multi-staee drying. It is passed first to a de-
watering
extruder 40 and then via conveyor or simple gravity drop or other suitable
means 41
to a drying extruder 42. In routine preferred embodiments consistent with that
illustrated in Fig. I producing natural rubber masterbatch with carbon black
filler, the
de-watering/drying operation will typically reduce water content to about 0 to
I
weight percent, more preferably .0 to .5 weight percent. Suitable dryers are
well
known and commercial.ly available, including for example, extruder dryers,
fluid bed
dryers, hot air or other oven dryers, and the like, such as French Mills
available from
the French Oil Machinery Co., (Piqua, Ohio, USA).
Dried masterbatch crumb from drying extruder 42 is carried by a cooling
conveyor 44 to a baler 46. The baler is an optional, advantaeeous feature of
the
apparatus of Fig. 1, wherein the dried masterbatch crumb is compressed within
a
chamber into form-stable compressed blocks or the like. Typically, 25 to 75
pound
quantities of the elastomer masterbatch are compressed into blocks or bales
for
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transport, further processing, etc. Alternatively, the product is provided as
pellets,
for example, by chopping the crumb.
The dimensions and particular design features of the coagulum reactor 14,
including the mixing zone/coagulum zone assembly, suitable for an embodiment
in
accordance with Fig. 1, will depend in part on such design factors as the
desired
throuehput capacity, the selection of materials to be processed, etc. One
preferred
embodiment is illustrated in Fig. 2 wherein a coagulum reactor 48 has a mix
head 50
attached to a coasulum zone 52 with a fluid-tight seal at joint 54. Fig. 2
schematically illustrates a first subsystem 56 for feeding elastomer latex to
the mixinc,
zone, subsystem 57 for feeding carbon black slurry or other particulate filler
fluid to
the mixing zone, and subsystem 58 for feeding an optional additive fluid,
pressurized
air, etc. to the mixing zone. The mix head 50 is seen to have three feed
channels 60,
61, 62. Feed channel 60 is provided for the natural rubber latex fluid and
feed
channel 62 is provided for direct feed of eas and/or additive fluid. In
connection with
preferred embodiments emplovinc, direct injection of additives, significant
advantaQe
is achieved in connection with hvdrocarbon additives or, more generally, non-
water
= miscible additives. While it is well Imown to employ emulsion intertnediates
to create
additive emulsions suitable for pre-blending with an elastomer latex,
preferred
embodiments in accordance with the present disclosure employing direct
injection of
additives can eliminate not only the need for emulsion intermediates, but also
the
eauipment such as tanks, dispersing equipment, etc. previously used in forming
the
emulsions. Reductions in manufacturing cost and complexity can, therefore, be
achieved. As discussed further below, the feed channel 61 through which slurry
is
fed to the mixing zone is preferably coaxial with the mixing zone and the
coasulum
zone of the coarzulum reactor. While only a single feed channel is shown to
receive
the elastomer latex fluid, any suitable number of feed channels mav be
arranged
around the central feed channel through which the slurry is fed to the mixing
zone.
Thus, for example, in the embodiment of Fig. 2 a fourth feed channel could be
provided through which ambient air or high pressure air or other gas is fed to-
the
mixing zone. Pressurized air may be injected likewise with the slurry through
the
central axial feed channel 61. Auxiliary feed channels can be temporarily or
permanently sealed when not in use.
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The coaeulum zone 52 of the coasulum reactor 48 is seen to have a first
portion 64 having an axial lens-th which may be selected depending upon desiEn
objectives for the particular application intended. Optionally, the coaaulum
zone may
have a constant cross-sectional area over all or substantially all of its
axial length.
Thus, for example, the coagulum reactor may define a simple, straight tubular
flow
channel from the mi.dng zone to the discharge end. Preferably, however, for
reasons
discussed above, and as seen in the preferred embodiment illustrated in the
drawings,
the cross-sectional area of the coagulum zone 52 increases progressively from
the
entry end 66 to discharse end 68. More specifically, the cross-sectional area
increases in the longtudinal direction from the entry end to the discharge
end. In the
embodiment of Fig. 2, the coasulum zone increases in cross-sectional area
progressively in the sense that it increases continuously following constant
cross-
sectional portion 64. References to the diameter and cross-sectional area of
the
coagulum reactor (or, more properly, the coagulum zone defined within the
coagulum reactor) and other components, unless stated otherwise, are intended
to
mean the cross-sectional area of the open flow passageway and the inside
diameter
of such flow passageway.
Elastomer composite, specifically, coagulated elastomer latex in the form of
masterbatch crumb 72, is seen being dischareed from the coagulum reactor 48
through a diverter 70. Diverter 70 is an adjustable conduit attached to the
coagulum
reactor at discharge ~nd 68. It is adjustable so as to selectively pass the
elastomer
masterbatch crumb 72 to any of various different receiving sites. This feature
advantageously facilitates removal of masterbatch crumb from the product
stream,
for example, for testincy or at the beginning of a production run when initial
process
instability may result temporarily in inferior product. In addition, the
diverter
provides design flexibility to direct product from the coagulum reactor to
different
post-processing paths. In accordance with the preferred embodiment of Fig. 1,
the
masterbatch crumb 72 beine dischar2ed from coasulum reactor 48 throuQh
diverter
70 is seen to be received by a drier 40.
The cross-sectional dimension of coagulum reactor 48 is seen to increase at
an overall angle a between entry end 66 and discharge end 68. Angle a is
ereater
than 0 and in preferred embodiments is less than 45 , more preferably less
than ] 5 ,
most preferably from 0.5 to 5 . The angle a is seen to be a half angle, in
that it is
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measured from the central longitudinal axis of the coaLyulum zone to a point A
at the
outer circumference of the coawlum zone at the end of the coasulum reactor, In
this
regard, it should be understood that the cross-sectional area of the upstream
portion
of the coaeulum reactor, that is, the portion near the entry end 66,
preferably
increases sufficiently slowly to achieve quasi-molding of the coagulum in
accordance
with the principles discussed above. Too larEe an angle of expansion of the
coagulum zone may result in the elastomer masterbatch not being produced in
desirable crumb form of globules or worms and simply spraying through the
coaeulum reactor. Increasing the bore of the coaQulum reactor too slowly can
result,
in certain embodiments, in bacl.-up or clogging of the feeds and reaction
product into
the mix head. In a downstream portion of the coaaulum zone, wherein the latex
has
been substantially coaQulated and flow has become essentially plug flow, the
coagulum zone may extend either with or without increase in cross-sectional
area.
Thus, reference here to the coa-a.tlum zone in preferred embodiments having a
progress'rvelv increasins cross-sectional area should be understood to refer
primarily
to that portion of the coagulum zone wherein flow is not substantially plug
flow.
The cross-sectional area of the coagulum zone (that is, at least the upstream
portion thereof, as discussed immediately above) may increase in step-wise
fashion,
rather than in the continuous fashion illustrated in the embodiment of Fis. 2.
In the
embodiment illustrated in Fig. 3, a continuous flow system for production of
elastomer masterbatch in accordance with the method and apparatus disclosed
here,
is seen to include a mix head/coagulum zone assembly wherein the cross-
sectional
area of the coagulum zone increases in step-wise fashion. Preferably, the
individual
sections of the coagulum zone in such a step-wise embodiment have a faired
connection to adjacent sections. That is, they combine to form a smooth and
senerally continuous coagulum zone surface, as opposed, for example, to a
sharp or
instantaneous increase in diameter from one section to the next. The coaQulum
zone
of Fig. 3 increases in three steps, such that there are four different
sections or sub-
zones 74 - 77. Consistent with the design principles discussed immediately
above,
the cross-sectional area of coagulum zone 53 increases from the entry end 66
to point
A at the discharge end 68 at an overall angle which achieves the necessary
flow
control in the upstrearn portion of the coagulum reactor. The first section 74
can be
taken as including (a) the constant diameter portion of the mix head 50
immediately
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CA 02511365 1997-03-25
WO 97136724 PCT/US97/05276
downstream of the mixing zone, and (b) the same or similar diameter portion
connected thereto at joint 54 at the entry end 66- This first section has a
constant
cross-sectional diameter D, and an axial dimension or length L,. In this first
section
74 the length L, should be greater than three times the diameteF D, more
preferably greater than five times D,, and most preferably from about 12 to 18
times
D,. Typically, this section will have a length of about fifteen timeslD Each
subsequent section preferably has a constant cross-sectional dimension and
cross-
sectional area approximately double that of the preceding (i.e., upstream)
section.
Thus, for example, section 75 has a constant cross-sectional dimension and a
cross-
secuonal area which is twice that of section 74. Similarly, the cross-
sectional area
of section 76 is double that of section 75, and the cross-sectional area of
section 77
is double that of section 76. In each of sections 75 - 77, the lenath is
preferably
areater than three times its diameter, more preferably about three to seven
times its
diameter and eenerally about five times its diameter. Thus, for example, in
section
76 longitudinal dimension L3 is preferably about five times its diameter D,.
A mix head and coa~~ulum zone assembly corresponding to the embodiment
of Fig. 3 is shown in Fig. 4 partially in section view. Mix head 50 is
inteQral with
coa.ulum zone extender 53 via joint 54. It defines a mixing zone wherein
multiple
feed channels 60, 61, 62 form a junction, with an elonsate, substantially
cylindrical
channel 80 substantially coaxial with the coasulum zone portion within
extender 53.
It will be recoanized that it is not essential to the operability of the
method and
apparatus disciosed here, to precisely define the boundaries of the mixing
zone and/or
coavLyulum zone. Numerous variations are possible in the design of the flow
channels
junction area, as will be apparent to those skilled in the art eiven the
benefit of the
present disclosure. In that reizard, as a generally preferred guideline, in
embodiments
of the type illustrated in Fig. 4, for example, the slurry tip 67 eenerally is
upstream
of the beQinning of cvlindrical ponion 80, being approximately centered
longitudinally
in the junction of the feed channels. In such embodiments, preferably, the
minimum
cross-sectional area defined by the imaainary cone from the slurry tip 67 to
the
circumferential perimeter at the beginning of the cviindrical portion 80 is
advantageously greater than, or at least equal to, the cross-sectional area of
the latex
feed channel 60. Preferably, both chartnel 80 and at least the upstream
portion of the
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coagulum zone wherein flow turbulence exists prior to substantially complete
coagulation of the elastomer latex, have a circular cross-section.
The means for feeding carbon black slurry or other particulate filler fluid is
seen to comprise a feed tube 82 extending substantially coaxially with the
mixing
chamber to an opening or slurry nozzle tip 67 which is open toward the
coagulum
zone. This is a highly advantageous feature of the preferred embodiments
discussed
here. The carbon black slurry, as noted above, is fed to the mixing zone at
very hieh
velocity relative the feed velocity of the latex, and the axial arraneement of
narrow
bore feed tube 82 results in excellent development of flow turbulence. The
diameter
D. of the channel 80 (whicti, as noted above, is preferably substantially
equal to the
diameter D, of immediately following portion of section 74 of the coaaulum
zone)
preferably is at least twice the inside diameter of slurry feed tube 82, more
preferably
about four to eight times the diameter of feed tube 82, typically about seven
to eight
times that diameter. Feed tube 82 is seen to form a fluid-tieht seal with the
entry port
83 at the upstream end of feed channel 61 of mix head 50. The diameter of the
axial
feed tube 82 is determined largely by the required volumetric flow rate and
axial
velocity of the slurry as it passes through the slurry nozzle tip 67 into the
mixinc,
chamber. The correct or required volume and velocity can be readily
deterrnined by
those skilled in the art eiven the benefit of this disclosure, and will be a
function, in
part, of the concentration and choice of materials. Embodiments such as that
illustrated and disclosed here, wherein the feed tube for the carbon black
slurry is
removable, provide desirable flexibility in manufacturing different
masteroatch
compositions at different times. The feed tube used in one production run can
be
removed and replaced by a larser or smaller bore tube appropriate to a
subsequent
production. In view of the pressure and velociry at which the slurry exits the
feed
tube, it may be referred to as a spray or jet into the mixing zone. This
should be
understood to meari in at least certain embodiments, high speed injection of
the slurry
into an area already substantially filled with fluid. Thus, it is a spray in
the sense of
its immediate distribution as it passes through the slurry nozzle tip , and
'not
necessarilv in the sense of free-flying material droplets in a simple
spreading
trajectory.
The additional feed channels 60 and 62 are seen to form a junction 84, 85,
respectively, with feed channe160 and downstream channel 80 at an angle P. The
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angle (3 may in many embodiments have a value from greater than 0 to less
than
180 . Typically, p may be, for example, from 30 - 90 . It is desirable to
avoid a
negative pressure, that is, cavitation of the latex fluid as it is entrained
by the high
velocity slurry exiting at slurry nozzle tip 67, since this may
disadvantageously cause
inconsistent mixing leading to inconsistent masterbatch product. Air or other
gas can
be injected or otherwise fed to the mixing zone to assist in breaking any such
vacuum.
In addition, an expanded feed line for the natural rubber latex leading to the
entry
port 86 of feed channel 60 is desirable to act as a latex fluid reservoir. In
the
preferred embodiment of Fig. 4, latex feed channel 60 intersects the mixing
zone
adjacent slurry nozzle tip 67. Alternatively, however, the latex feed channel
can
intersect the mixing channel upstream or downstream of the slurry nozzle tip
67.
The carbon black slurry or other particulate filler fluid typically is
supplied to
feed tube 82 at a pressure above about 300 psig, such as about 500 to 5000
psig, e.g.
about 1000 psig. Preferably the liquid slurry is fed into the mixing zone
through the
slurry nozzle tip 67 at a velocity above 100 ft. per second, preferably about
100 to
about 800 ft. per second, more preferably about 200 to 500 f3. per second, for
example, about 350 feet per second. Arrows 51 in Fie. 4 represent the general
direction of flow of the elastomer latex and auxiliary feed materials through
feed
channels 60 and 62 into the channel 80 below slurry nozzle tip 67. Thus, the
slurry
and latex fluids are fed to the mixing zones at greatly different feed stream
velocities,
in accordance with the numbers set forth above. While not wishinQ to be bound
by
theory, it presently is understood that the differential feed achieves latex
shear
conditions in the mixing zone leading to good macro-dispersion and
coagulation.
An alternative preferred embodiment is illustrated in Figs. 5 and 6 wherein
the
single axial feed tube 82 in the embodiment of Fig. 4 is replaced by multiple
axially
extending feed tubes 90 - 92. Even greater numbers of feed tubes may be
employed,
for example, up to about 6 or 8 axially-eh-tending feed tubes. Advantageously,
production flexibility is achieved by using different feed tubes of different
diameter
for production of different formulations. Also, multiple feed tubes can be
used
simultaneously to achieve good flow turbulence within the mixing zone and
coagulum
zone of the coagulum reactor.
An alternative embodiment of the mix head is illustrated in Fig. 7. Mix head
150 is seen to define a mixing zone 179. An axial feed channel 161 receives a
feed
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tube 182 adapted to feed carbon black slurry or other particulate filler fluid
at high
velocity into the mixina chamber 179. It can be seen that the central bore in
feed tube
182 terminates at slurry nozzle tip 167. A constant diameter nozzle land 168
is
immediately upstream of slurry nozzle tip 167, leading to a larger bore area
169.
Preferably the axial dimension of land 168 is about 2 to 6, e.g. about 5,
times its
diameter. A second feed channel 160 forms a junction 184 with the mixing zone
179
at a 90 angle for feeding elastomer latex fluid to the mixing zone. The cross-
sectional diameter of the latex fluid feed channel 160 is substantially larger
than the
cross-sectional diameter of the slurry nozzle tip 167 and land 168. Without
wishincy
to be bound by theory, the axial elonaation of nozzle land 168, coupled with
the
expanded diameter bore section upstream of the nozzle land, is believed to
provide
advantaQeous stabilitv in the flow of slurry through feed tube 182 into the
mixing
zone 179. The bore of feed tube 182 is found to function well with a 20
chamfer,
that is, conical area 169 which expands in the upstream direction at about a
20
anale. Downstream of mixino zone 179 is an elongate coa2ulum zone. Consistent
with the principles discussed above, such coa¾ulum zone need be only
maroinally
eloneate. That is, its axial dimension need be only marszinally Ionger than
its
diameter. Preferably, however, a proeressively enlarized coaaulum zone is
used.
As discussed above, coawlation of the elastomer masterbatch is substantially
complete at or before the end of the coasulum reactor. That is, coaaulation
occurs
within the coaoulum zone of the coaaulum reactor without the necessity of
adding
a stream of coaeulant solution or the like. This does not exclude the
possioility that
some initial coagulation occurs in the mixing zone. The mixinQ zone may be
considered an extended ponion of the coagulum zone for this purpose. Also,
reference-to substantially complete coagulation prior to the elastomer
masterbatch
exitins the coaeulum reactor is not meant to exclude the possibility of
subsequent
processing and follow-on treatment steps, for any of various Purposes
appropriate to
the intended use of the final product. In that regard, substantially complete
coagulation in preferred embodiments of the novel method disclosed here
employing
natural rubber latex means that at least about 95 weieht percent of the rubber
hydrocarbon of the latex is coagulated, more preferably at least about 97
weight
percent, and most preierably at least about 99 weiaht percent is coagulated.
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The method and apparatus disclosed and described here produce elastomer
composites having excellent physical properties and performance
characteristics.
Novel elastomer composites of the present invention include masterbatch
compositions produced by the above-disclosed method and apparatus, as well as
intermediate compounds and finished products made from such masterbatch
compositions. Notably, elastomer masterbatch can be produced using natural
rubber
latex (latex concentrate or field latex), along with various grades of carbon
black
filler, having excellent physical properties and performance characteristics.
Carbon
blacks presently in broad commercial use for such application as tire tread
have been
used successfullv, as well as carbon blacks heretofore considered unsuitable
for
commercial use in known production apparatus and methods. Those unsuitable
because their high surface area and low structure rendered them impractical to
achieve acceptable levels of macro-dispersion at routine commercial loading
levels
for the carbon black and/or to preserve the molecular weight of the elastomer
are
highly preferred for the novel elastomeric masterbatch compositions disclosed
here.
Such elastomer composites are found to have excellent dispersion of the carbon
black
in the natural rubber, tooether with good preservation of the molecular weight
of the
natural rubber. Moreover, these advantageous results were achieved without the
need for a coagulation step involving a treatment tank or stream of acid
solution or
other coagulant. Thus, not only can the cost and complexity of such coagulant
treatments be avoided, so too the need to handle effluent streams from such
operations.
Ptior known dry mastication techniques could not achieve equal dispersion
of such fillers without sio-ificant molecular weieht degradation and,
therefore, could
not produce the novel natural rubber masterbatch compositions made in
accordance
with certain preferred embodiments of the present invention. In that regard,
novel
elastomer composites are disclosed having excellent macro-dispersion of the
carbon
black in the natural rubber, even of carbon blacks having a structure to
suriace area
ratio DBPA:CTAB less than 1.2 and even less than 1.0, with hieh molecular
weight
of the natural rubber. Known mixing techniques in the past did not achieve
such
excellent macro-dispersion of carbon black without significant molecular
weight
degradation of the natural rubber and, therefore, did not produce the novel
masterbatch compositions and other elastomer composites of the present
invention.
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Preferred novel elastomer masterbatch compositions in accordance with this
disclosure, having carbon black macro-distribution levels not heretofore
achieved, can
be used in place of prior known masterbatch having poorer macro-dispersion.
Thus,
masterbatch disclosed here can be incorporated into cured compounds in
accordance
with known techniques. Such novel cured compounds are found in preferred
embodiments to have physical characteristics and performance properties
eenerally
comparable to, and in some instances significantly better than, those of
otherwise
comparable cured compounds comprising masterbatch of poorer macro-dispersion.
Masterbatch can be produced in accordance with the present invention, however,
with reduced mixing time, reduced energy input, and/or other cost savings.
Particularly with respect to certain preferred embodiments, natural rubber
latex and carbon black filler masterbatch can be produced havina excellent
physical
characteristics and performance properties. Excellent macro-dispersion of the
carbon
black is achieved, even using carbon blacks of exceptionally high surface area
and low
structure, without the degree of degradation of the natural rubber which would
be
caused by dry mastication for sufi=tcient time and at sufficient intensity
levels to
achieve the same degree of carbon black dispersion. Especially advantageous in
this
regard are novel natural rubber masterbatch compositions wherein a hieh degree
of
dispersion is achieved, using carbon blacks having structure to surface area
ratio,
DBPA: CTAB of less than 1.2 and even less than 1Ø As used here, the carbon
black
structure can be measured as the dibutyl phthalate adsorption (DBPA) value,
expressed as cubic centimeters of DBPA per 100 grams carbon black, accordinv
to
the procedure set forth in ASTM D2414. The carbon black surface area can be
measured as CTAB expressed as square meters per gram of carbon black,
according
to the procedure set forth in ASTM D3765-85- Novel natural rubber masterbatch
is
achieved, therefore, having heretofore unachievable combinations of physical
characteristics such as molecular weight distribution and filler dispersion
levels,
and/or incorporating heretofore unsuitable fillers such as carbon black of
extraordinarily high surface area and low structure. The dispersion quality of
natural
rubber masterbatch produced in accordance with the methods and apparatus
disclosed here can be demonstrated with reference to the well known
characteristics
of MW, (weight averaoe) and macro-dispersion. Specifically, the macro-
dispersion
level in masterbatch produced in accordance with preferred embodiments is
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sianificantly better than that in masterbatch of approximately equal MW.,
produced
using dry mastication. Most notably, the dispersion quality of these preferred
embodiments does not depend significantly on the morphology of the carbon
black
filler. It will be recoanized that other factors affecting the level of
dispersion
5. achievable using the method and apparatus disclosed here, include the
concentration
of the carbon black in the slurry, total energy input into the slurry and
energy input
during mixing of the fluid streams, etc.
The macro-dispersion quality of carbon black in natural rubber masterbatch
disclosed here is significantly better than that in previously knoAm
masterbatch of
approximately equal MW., (weight average). In some preferred embodiments of
novel elastomer composites, excellent carbon black distribution is achieved
with
MWso, approximately that of natural rubber in the field latex state, (e.g.,
approximately 1,000,000) a condition not previously achieved. The dispersion
quality advantage is especially significant in the above mentioned preferred
embodiments using carbon black with low structure and high surface area, e.g.,
DBPA less than 110cc/100g, CT.4B greater than 45 to 65 m'-/g, and DBPA:CTAB
less than 1.2 and preferably less than 1Ø
EX AMPLES
Test Procedures
The following test procedures were used in the examples and comparisons
presented below.
1. Bound Rubber: A sample weighing.5 g. _.025 g. is weighed and placed
in 100 ml. toluene in a sealed flask and stored at ambient temperature for
approximately 24 hours. The toluene is then replaced with 100 ml. fresh
toluene and
the flask is stored for 4 days. The sample is then removed from the solvent
and air-
dried under a hood at ambient temperature for 24 hours. The sample is then
further
dried in a vacuum oven at ambient temperature for 24 hours. The sample is then
weighed and the bound rubber is calculated from the weight loss data.
2. M'W,o,: As used in this disclosure and in the claims, MWso, refer to weight
average molecular weight of the sol portion of the natural rubber. Standard
GPC
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techniques for molecular weight measurement were followed in accordance with
the
followincl,:
2.1 Two 10um 106 A columns, a l0}im 500A column and a 10Fcm mixed
bed column from Polymer Laboratories, UK.
2.2 UV detection at 215nm.
2.3 Solvent: Tetra hydro furan (THF)
2.4 Concentration, nominally 2mg/ml in THF.
2.5 Samples are left to dissolve in THF for 3 days, stabilized with BHT.
=:.. 2.6 Solutions are centrifuged to separate any gel and the supernatant is
injected onto the column.
2_7 SamDle PreDarations Sample preparation is designed to.prepare sol
concentrations in the range of 0.5 to 0.05 percent by weight to
provide a good detector response for accurate measurement of the
molecular weight distribution. Depending on the filler loading,
sample weight is adjusted according to the following formula:
sample wt. = (100 = filler loading (phr))*20/l00 mg -/- 2 mg
Samples are placed in UV protected vials and dissolved in 4 niL of
stabilized tetrahydrofuran (THF) containing 0.02% butylated-
hydroxv(toluene (BHT) for three days. The supernatant from the
dissolution step, containing mostly the sol portion, is transferred to
Teflon centrifuge tubes and centrifuged in an Avanti 30 (Beckman)
centrifuge for 60 minutes at 26,000 revolutions per minute
(corresponding to a maximum field strength of 57,500 g). At this
field strength, a majority of the gel phase sediments allowing a gel-
free supernatant. This gel-free solution is diluted at 1:5, again using
stabilized THF. At this point, the samples are transferred to GPC
vials and placed inside a Waters 717 Auto-Sampler (Water
Corporation, Milford, Massachusetts, USA) in preparation for the
GPC testing.
Mc_?ecular Weight Determination The weight average molecular
w,r.t of the sol portion MWm, is then determined. Using Millenium
so..,vare (available from Waters Corporation, Milford,
Massachusetts, USA) a baseline is defined using a valley-to-valley
mode within the time increments of 15 and 35 minutes. This time
increment is appropriate for the column set described above in
paragraph 2.1 with the mobile phase flow rate set at 0.75 mL/tnin.
Once a reasonable baseline is established the distribution can be
determined. The elution time is converted to molecular weiaht.
Polystyrene solutions made from commercially available standards
2114
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(EasiCal : Polymer Laboratories, U.K.) are prepared containing a
series of molecular weights with very narrow distributions. The
conversion of polystyrene molecular weieht to polyisoprene
molecular weiQht equivalents is based on the universal calibration
method of Benoit and coworkers. The hydrodynamic radius is
proportional to the product of the molecular weiaht times the intrinsic
viscosity. After convertina the polystyrene molecular weiehts to
polyisoprene equivalents, the calibration curve relates absolute
molecular weieht to elution time. The standards are run under
conditions identical to the samples, and the standards are intec-rrated
to assiizn the appropriate molecular weight for a Qiven elution time,
based on a best fit to the standards data. Once the time based
distribution is properly converted to molecular weight, the
appropriate molecular weight averages are calculated by the Waters'
== . 15 Millenium software.
3. Mooney Viscosity: Standard procedures were followed for ML
(1+4)@ 100 C. 4. Test Sample Cure Conditions: Test pieces were cured to
150 C for the time periods indicated below:
4.1 Tensile Sheet: 20 min.
4.2 Resilience: 23 min.
4.3 Hardness: 23 min.
4.4 Heat Build-Up: 25 min.
5. Dispersion: The Cabot Dispersion Chart method is used with subjective
evaluation of 50x optical micro¾raphs. (ASTM D2663 Method).
6. Stress-Strain: Tested to BS903:A2 and ISO 37.
7. Hardness: Tested to ISO 48 (1994), temperature 23 C.
8. Resilience: Tested to BS903:A8 (1990), Method A, temperature 23 C (8
mm molded disc test piece).
9.- Heat Buildup: Tested to ASTM D623, Method A.
9_ 1 Start temperature: 23 C
9.2 Static load: 24 lbs.
9.3 Stroke: 0.225 inches.
9.4 Frequency: 30 Hz.
9.5 Run for 30 minutes. '
3~
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10. Tan S: Measured on Rheometrics model RDS II. Reported values are
maximums from strain sweeps. Strain sweeps at 0 , 30 , and 60 C, 1 Hz, and
0.1%
to 60% strain.
11. Crack Growth Resistance: Measured in accordance with ASTM D3629-94
; 5 Examole A
Elastomer masterbatch was produced in accordance with the present
invention. Specifically, an elastomer masterbatch was produced comprising
standard
natural rubber field latex from Malaysia with 52.5 phr filler consisting of
carbon black
of commercial erade N234 available from Cabot Corporation. The properties of
the
natural rubber field latex are provided in Table I below.
Table I Natural Rubber Latex Properties
% Dn= % Total Nitroeen Volatile ML(1 +4)
Additives Rubber Solids % Ash I ppm I Fatty Aeid r! 100 C
0.15~I l-Il~'S' 28.4 34.2 0.38 0.366 0.052
68
0.3%NH3,
ZnO, TMTD'
a. HNS: hydroxylamine neutral sulfate, Mooney viscosity stabilizer.
b. ZnOITMTD: used for biological preservation, typically 0.025% of 1:1
mixture.
The full compound formulation is set forth in Table 2 below, and is
representative of
a commercial truck tire tread known to have excellent resistance to reversion
during
cure.
3b
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Table 2 Masterbatch Formulation
Ingredient Parts bv Wt.
Rubber 100
Carbon Black 52.5
ZnO 4.0
Stearic acid 2.0
6PPD (antioxidant) 2.0
Sunproof Improved (wax) 2.0
Ennerflex 74 (aromatic oil) 3.0
Total 165.5
The elastomer masterbatch production apparatus was substantially identical to
the
apparatus described above with reference to Figs. I and 7 of the drawings. The
slurry nozzle tip (see reference No. 167 in Fig. 7) was .039 inch diameter
with a land
(see reference No. 168 in FiQ. 7) havine an axial leneth of 0.2 inch. The
coaQulum
zone was 0. 188 inch diameter and had .985 inch axial length of constant
diameter
between the mixing zone and its discharae end. Preparation of the masterbatch
is
described in further detail immediately below.
1. Carbon Black Slurrv Preoaration. Baas of carbon black were mixed with
deionized water in a carbon black slurry tank equipped with an aaitator. The
amtator broke the pellets into fragments and a crude slurry was formed with
12.5 wt.%= carbon black. During operation, this slurry was continually
pumped by an air diaphragm pump to a colloid mill for initial dispersion. The
slurry was then fed by a progressing cavity pump to a homogenizer,
specifically, a model M3 homogenizer from APV Gaulin, Inc. The
homogenizer produced a finely ground slurry. The slurry flow rate from the
homoQenizer to the mixing zone was set by the homoeenizer speed, the
homooenizer acting as a high-pressure positive displacement pump. Slurry
flow rate was monitored with a Micromotion mass flow meter. The carbon
black slurry was fed to the homogenizer at a pressure ranging from 50 to -100
psiQ and the homogenization pressure was set at 4000 psig, such that the
slurry was introduced as ajet into the mixing zone at a flow rate of 4.1 to
4.4
lbimin and at a velocity of about 130 ft/sec.
3l
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2. Latex Deliverv. The latex was charged to a 100 eallon pressurized feed
tank.
Antioxidant emulsion was added to the latex prior to chargine. Antioxidants
were added consisting of 0.3 phr tris nonyl phenyl phosphite (TNPP) and 0.4
phr Santoflex 134 (all.yl-aryl p-phenylene diamine mixture). Each of the
antioxidants was prepared as a 15 wt.% emulsion using 3 parts potassium
oleate per 100 parts antioxidant along with potassium hydroxide to adjust the
emulsion to a pH of approximately 10. Also, 3 phr extender oil was added.
Air pressure (51 psig) was used to move the latex from the feed tank to the
mixins zone of the coasulum reactor. The latex flow rate was 3.2 to 3.4
lbs/min and about 3.8 feet per second, and was automatically metered and
controlled with a Micromotion mass flow meter and a rubber tube pinch
valve. The desired carbon black loading of a 52.5 phr was obtained by
maintaining proper ratio of the latex feed rate to the carbon black slurry
feed
rate.
3. Carbon Black and Latex MixinQ. The carbon black siurry and latex were
mixed by entraininc, the latex into the carbon black slurry. During
entrainment, the carbon black was intimately mixed into the latex and the
mixture coagulated. Soft, wet spongy "worms" of coagulum exited the
coaaulum reactor.
4. Dewaterine. The wet crumb dischareed from the coagulum reactor was
about 79% water. The wet crumb was dewatered to about 5 to 10%
moisture with a dewatering extruder (The French Oil Mili Machinery
Company; 3'/~ in. diameter). In the extruder, the wet crumb was compressed
and water squeezed from the crumb and through a slotted barrel of the
extruder.
5. Drving & CoolinE!. The dewatered crumb dropped into a second extruder
where it was aeain compressed and heated. Water was flashed off upon
expulsion of the crumb throuah the dieplate of the extruder. Product exit
temperature was approximately 300 F and moisture content was about 0.5
to I wt.%. The hot, dry crumb was rapidly cooled (approximately 20
39
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seconds) to about 100 F by a forced air vibratinv convevor. The resultin~
dry crumb had about 66. wt. =o rubber solids and about 33. wt.% carbon
black.
Examnle B
A control masterbatch was prepared by dry mastication. The control
employed the same formulation as Example A (see Table 2 above), except that
the
natural rubber was SMR 10 rather than latex. It was prepared by premastication
of
the rubber in a OOC Banbury mixer (approximately 3 kg) at 50 rpm using 10 phr
carDon black. The premastication was performed for approximately 3 min. to a
total
of 800 M7/m3.
Comnarisons of ExamDle A and Examnle B
The masterbatch of Example A and the control masterbatch of Example B
were compounded in a two-stase mixing operation in a OOC Banbury mixer
(approximately 3 kcl,). Table 3 below sets forth the mixing schedule for the
first
stage. It can be seen that the Example A masterbatch followed a modified
mixing
schedule.
Table 3 Stage 1 Mixing Schedules
Time Example A Example B
(min) Dry Mix Control
0.0 All ineredients Pre-Masticated Rubber
0.5 Carbon Black and Oil
1.0 Sweep
1.5 Remainina InQredients
2.0
2-5 Sweep
3.0
X dump at approx. 700 MJ/m' dump at approx. 1,000 MJ/m'
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In the second stap-e, curatives listed in Table 4 below were added with a
further
mixing cycle of 500 MJ/m'.
Table 4 Final Stage Curative Addition
Ingredient Parts bv Wt.
Stage 1 compound 165.5
Goodyear Winstay 100 (antioxidant) 1.0
TBBS (sulfur accelerator) 1.8
Suifur 1.0
Total 169.3
Thus, Banbury mixing energy for the compounding of Example A masterbatch was
about 53% of the Banbury mixin~ energy required for the premastication and
compounding of the control material of Example B. Despite the reduced ener~y
input, the Example A material was found to have very good macro-dispersion,
and
the molecular weifzht (weiQht average) of its sol portion MW,, was
substantially
hiaher than that of the control. These data are summarized in Table 5 below.
Table 5 Compounding and Curing Data
Sample Mix Enera-v (MJ/m') ML (1T4,100C) MW
Pre- Staee I Final Total Sta¾e I Final wt av.
Masticate
Example A 0 694 500 1,194 102 72 ~ 444,900
Example B
800 965 500 2,265 92 67 327,000
Additional testing results for the cured (unaQed) Example A and control
material are
set forth in Table 6 below.
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Table 6 Additional Test Data
Sample
ample Hardness 100% Modulus 300% Modulus Tensile (MPa)
~a) (MPa)
Example A 71 2.82 J16.1 28.7
Example B 72 3.12 ( 16.2 28.5
Sample Elongation at Resiliance (%) Heat Build-Up Max Tan Delta
Break (%) ( C) 60 C 30 C 0 C
Example A 526 56.5 70.5 0.203 I 0.21
40 0.290
Example B 511 57.6 76.5 I 0.206 0.236 0.286
Examole C
Elastomer masterbatch was produced in accordance with the present
invention. Specincally, an elastomer masterbatch was produced comprisinc
standard
natural rubber field latex from Malaysia with 55 phr filler consisting of
carbon black
of commercial iz-ade Re2al 660 avaiiable from Cabot Corporation. The
compound
formulation (excluding minor ordinary latex additives) is set forth in Table 7
below.
Table 7 Masterbatch Formulation
InQredient Parts bv Wt.
Rubber 100
Carbon Black 55.
Santoflex 134 (antioxidant) 0.4
TNPP (antioxidantl 0 3
Total 155.7
The elastomer masterbatch production apparatus was substantially identical to
the
apparatus described above with reference to Figs. 1, 3 and 7 of the drawinas.
The
sluny nozzle tip (see reference No. 167 in Fig. 7) was .025 inch diameter with
a land
(see reference No. 168 in Fi~. 7) having an axial lengih of 0.2 inch. The
coaeulum
zone (see No. 53 in Fi;. 3) included a first portion of .188 inch diameter.
and
approximately .985 inch axial lens*th (being partly within the mix-head and
party
within the extender sealed thereto); a second portion of .266 inch diameter
and 1.6
inch axial length; a third portion of .376 inch diameter and 2.256 axial
length; and a
fourth portion of .532 inch diameter and 3.190 inch axial length. In addition,
there
At1
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are axialiv short, faired interconnections between the aforesaid portions.
Preparation
of the masterbatch is described in further detail immediately below.
1. Carbon Black Slurrv PreDaration. Bass of carbon black were mixed with
deionized water in a carbon black slurry tank equipped with an agitator. The
agtator broke the pellets into fragments and a crude slurry was formed with
14.9 wt.% carbon black. The crude slurry was recirculated using a pipeline
grinder. During operation, this slurry was continually pumped by an air
diaphragm pump to a colloid mill for initial dispersion. The slurry was then
fed by a progressing cavity pump to a homogenizer, specifically,
Nlicrofluidizer Model M?10 from Microfluidics International Corporation for
pressurizing and shear, to produce a finely ground slurry. The slurry flow
rate from the microfluidizer to the mixing zone was set by the microfluidizer
speed, the microfluidizer actine as a high-pressure positive displacement
pump. Slurry flow rate was monitored with a Micromotion mass flow
meter. The carbon black slurry was fed to the microfluidizer at a pressure of
about 130 psig and the output pressure was set at 3000 psig to an
accumulator set at 450 psig output pressure, such that the slurry was
i.-ttroduced as ajet into the mixing zone at a flow rate of about 3.9 !b/min
and
at a velocity of about 300 ft/sec.
2. Latex Deliverv. The latex was charged to a tank, specifically, a 55 gallon
feed drum. Antioxidant emulsion was added to the latex prior to charging.
Antioxidants were added consisting of 0.3 phr tris nonyl phenyl phosphite
(TNPP) and 0.4 phr Santopiex 134 (alkvi-aryl p-phenylene diamine
miycture)= Each of the antioxidants was prepared as a 40 wt.% emulsion using
4 parts potassium oleate per 100 parts antioxidant along with potassium
hydroxide to adjust the emulsion to a pH of approximately 10. A peristaltic
pump was used to move the latex from the feed tank to the mixing zone of
the coagulum reactor. The latex flow rate was 3.2 to 3.3 lbs/min and about
3.9 feet per second, and was metered with a Endress + Hauser (Greenwood,
Indiana, USA) mass flow meter. The desired carbon black loading of a 55
4y
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phr was obtained by maintaining proper ratio of the latex feed rate to the
carbon black slurry feed rate.
3. Carbon Black and Latex Mixin2. The carbon black slurry and latex were
mixed by entraining the latex into the carbon black slurry. During
entrainment, the carbon black was intimately mixed into the latex and the
mixture coaUulated. Soft, wet sponay "worms" of coagulum exited the
coawlum reactor.
4. Dewaterine. The wet crumb dischareed from the coagulum reactor was
about 78% water. The wet crumb was dewatered to about 12 to 13%
moisture with a dewatering extruder (The French Oil Mill Machinery
Company; 3'/=_ in. diameter). In the extruder, the wet crumb was compressed
and water squeezed from the crumb and through a slotted barrel of the
extruder.
5. DrvinQ & Coolina. The dewatered crumb dropped into a second extruder
where it was asain compressed and heated. NA'ater was flashed off upon
expulsion of the crumb through the dieplate of the extruder. Product exit
temperature was approximately 280 F to 370 F and moisture content was
about 0.3 to .4 wt.%. The hot, dry crumb was rapidly cooled (approximately
seconds) to about 100 F by a forced air vibrating conveyor.
20 Examples D and E
Two dry mix control masterbatches were prepared by dry mastication. The
controls employed the same formulation as Example C (see Table 7 above),
except
that in Example D the rubber was RSS 1 NR rather than latex. In Example E the
rubber was SMR 10 NR. Each was prepared by premastication of the rubber in a
BR
Banbury mixer. The rubber of Example D was masticated at 118 rpm for 10
minutes.
The rubber of Example E was masticated at 77 rpm for 4 minutes.
Comoarison of Examoles C. D and E
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The masterbatch ofExample C and the two control masterbatches of Example
D and E were compounded in a BR Banbury mixer. Table 8 below sets forth the
compounding schedules.
tF4
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Table 8 Compounding Schedules
1 Pre-Mastication Staae I Mixing StaQe IT (Final)
Masterbatch Mixing
No No BR Banbury 77
Example C rpm, 4.5 min.
BR Banbury BR Banbury BR Banbury 77
Example D mixer 118 rpm, mixer 77 rpm, 3 rpm, 4.5 min.
min. min.
BR Banbury BR Banbury BR Banbury 77
5 Example E mixer 77 rpm, 4 mixer 77 rpm, 8 rpm, 4.5 min.
min. min.
The compounding formulation is eiven in Table 9 below.
Table 9 StaQe II Curative Addition
Inaredient Parts bv Wt.
10 Example 4 Masterbatch or
Example 5 or 6 Staae 1 Dry Mi.x 155
*Azo 66 (zinc oxide) 4.0
'*Hystrene 5016 (stearic acid) 2.0
$Santoflex 13 (antioxidant) 2.0
*Sunproof Improved (wax) 2.0
*Wingstay 100 (antioxidant) 1.0
*Santocure NS (sulfur accelerator) 1.8
Sulfur 1.0
Total: 168.8
. All three compounds exhibited well-behaved cure with minimal reversion.
Despite
the reduced energy input, the Example C material was found to have
sisnificantly
better macro-dispersion than'the dry mix controls, and the molecular weiQht
(weight
average) of its sol portion MWw was substantially hieher than that of the
controls.
These data are summarized in Table 10 below.
* trads-mark
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Table 10 Masterbatch and Compound Properties
I Example C Example D Example E
Masterbatch Properties
Mooney Viscosity 125 124 126
Mi(1+4)@looc
Bound Rubber 50 32 44
(%)
MW sol (110') 0.678 -466 .463
Percent .12 1.48 2.82
iindispersed Area
(D%)
Compound Properties
Hardness 62 , 65 62
100% Modulus 239 315 270
(psi)
300% Modulus 1087 1262 1216
(psi)
Tensile strength 4462 4099 4344
(psi)
Elongation, % 675 591 600
Max. Tan Delta 0.189 -237 -184
1; 60 C (Strain
Sweep)
Crack GroNth 0.8 5.0 5.8
Rate
(catlper million
cycles)
Additional Examples and Comnarisons
Hiahly preferred elastomer composites in accordance with the present
invention were produced in accordance with the method and apparatus disclosed
above. In particular, novel masterbatch compositions were formed of natural
rubber
latex and carbon black filler, havine significantly better macro-dispersion
levels and/or
natural rubber molecular weight than heretofore found in known compositions
formed of the same or similar starting materials. Fig. 8 shows the surface
area and
yto
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structure of various carbon black fillers used in these preferred masterbatch
compositions, specifically, the CTAB surface area expressed as square meters
per
uam of carbon black per ASTM D3765-85 and dibutyl phthalate absorption (DBPA)
value expressed as cubic centimeters of DBP per hundred erams carbon black per
ASTM D2414 are shown. Fie. 8 is seen to be divided into three different re6ons
of
carbon blacks. Region I contains carbon blacks having lower structure and
higher
surface area, being those most difficult to disperse in natural rubber and
other
elastomers using traditional dry mixing techniques. Hence, carbon blacks of
Region
I are not used commercially as widely as other carbon blacks. Masterbatch and
cured
elastomeric compositions made with Region I carbon blacks usin~ traditional
dry
mixing techniques have poorer macro-dispersion and typically lower The
carbon blacks of Region II have higher structure than those of Region I.
Typically,
they achieve reasonably good dispersion in natural rubber for vehicle tire
products
and the like if subjected to such extended dry mixing that the MWof the
natural
rubber is siznificantly degraded. The carbon blacks of Region III of Fig. 8
have
lower surface area relative their structure. Accordingly they have been used
with
acceptable dispersion in natural rubber via dry mixing, but again, with
undesirable
degradation of MW,. The dispersion of carbon blacks of all three regions of
Fig. 8,
specifically, macro-dispersion, is significantly improved in the elastomer
composites
disclosed here, and can be achieved with significantly higher MWso, of the
natural
rubber in accordance with preferred embodiments.
Control Samples I - 443
Control samples of masterbatch were prepared by dry mixing in accordance
with the following procedures, for purposes of comparison to elastomer
composites
of the present invention.
1. Mastication of Natural Rubber
In order to produce dry masterbatches with a wide range of molecular weight,
commercial natural rubber (RSS 1, SMR CV, and SMR 10) bales were pre-
masticated
in a BR banbury mixer usiniz the following conditions (fill factor: 0.75):
~i~
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Table 11 Natural Rubber iYlastication Conditions
Sample Mastication Rotor Speed Cooling Mastication
Code (rp m) Water time (min.)
M 1 No I
M2 Yes 77 On 4
M3 Yes 118 On 6
M4 Yes 118 On 10
2. Mixing Carbon Black with Pre-Masticated Natural Rubber
In order to prepare natural rubber dry masterbatches with different levels of
macro-dispersion quality, the following mixing procedures were used in a BR
Banburv mixer_ The fill factor was 0.70_ The masterbatch inszredients and
mixin-,
procedures are described as follows in Table 12.
Table 12 Natural Rubber Dry Masterbatch Formulation
Ingredient phr
(Pans per hundred pans of rubber bY
weieht)
Natural Rubber 100
Carbon Black See Tables Below
Oil See Tables Below
Santofex (antioxidant) 0.4
TNPP (antioxidant) 0.3
Mixina Procedures:
0 minute: Add pre-masticated natural rubber (77 rpm, 45 C)
1 minute: Add black, oil and antioxidants
Different levels of macro-dispersion were produced by dr 'xing sampies of M 1
throueh M4 pre-masticated natural rubber for different mi. , times, as shown
in
_= 5 Table 13, below. For example, sample code M2D1 in Table 13 indicates a
control
sample of premasticated natural rubber M2 (see Table 11, above) mixed for 10
minutes in accordance with the formulation of Table 12.
~tS
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Table 13 Mixing Times
Dry NR Masterbatch Pre-Masticated NR Mixing Time
Sample Code
MID4 M1 4
M1D3 M1 6
MID2 M1 8
M1D1 M1 10
M2D4 M2 4
M2D3 M2 6
M2D2 M2 8
M2D 1 M2 10
M3D4 M3 4
M3D3 M3 6
M3D2 M3 8
M3D 1 M3 10
M4D4 M4 4
M4D3 M4 6
M4D2 M4 8
M4DI M4 10
3. Final mixing of Natural Rubber Masterbatch Control Samples
To evaluate compound performance, additional ingredients were added to
the dry masticated natural rubber masterbatch control samples of Table 13 in
accordance with the formulation shown in Table 14.
`fQ
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Table 14 Additional Ingredients for Final Mixing
Ingredient Amount (phr)
Azo 66 (zinc oxide) 4.0
Hystere 5016 (stearic acid) 2.0
Santoflex 13 (antioxidant) 2.0
Sunproof Improved (wax) 2.0
Wingstay 100 (antioxidant) 1.0
Santocure NS (sulfur accelerator) 1.8
Sulfur 1.0
The compounds were cured in accordance with standard cure techniques at
150 C until at least substantially completely cured, typically between 10 and
30
minutes. In that regard, the same or substantially the same final mixing
procedures,
including the formulation given above in Table 14, were used for all control
samples,
as well as all samples of elastomer composites of the invention prepared in
the
manner described below (see "Preferred Embodiments Examples) which were cured
and tested for compound properties and performance characteristics.
The following tables 15 - 23 set forth the sol molecular weight MW, , and
macro-dispersion D(%) of control samples I through 443. The samples are
grouped
in the tables according to choice of carbon black. Within a eiven table, the
samples
are grouped by choice of natural rubber and by carbon black loading and oil
loading.
The table headinas show this information in accordance with standard
nomenclature.
Thus, for example, the headinc, for Table 15 "N330/55phr/0" indicates 55phr
N330
carbon black with no oil. The table sub-headings show the choice of natural
rubber_
Specifically, control samples 1 through 450 are seen to be made from standard
grade
natural rubber RSSI, SMRCV and SMRIO. Technical description of these natural
rubbers is widely available, such as in Rubber World MaQazine's Blue Book
published by Lippincott and Peto, Inc. (Akron, Ohio, USA). The molecular
weight
MW, , of the natural rubber prior to any premastication (MI) and after the
various
amounts of premastication (M2-M4) also are shown below in Tables 15 - 23.
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Table 15
N330/55ahr/0
RSS1 SMRCV
Code Sample Mw,,, D('/) Samp/e Mw,, D('/)
No. (K) No. (K)
M1 1300 971
M2 932 725
M3 664 596
M4 485 482
M1D1 1 465 4.24 17 426 4.35
M1D2 2 571 3.70 18 467 3.89
MID3 3 706 4.79 19 486 4.86
M1 D4 4 770 4.52 20 535 4.78
M2D1 5 445 3.66 21 380 2.44
M2D2 6 490 2.68 22 398 3.71
M2D3 7 512 3.68 23 433 4.30
M2D4 8 581 3.93 24 498 5.81
M3D1 9 373 1.33 25 342 3.79
M3D2 10 402 2.50 26 358 4.35
M3D3 11 407 2.98 27 371 5.55
M3D4 12 452 3.35 28 408 5.01
M4D1 13 311 3.63 29 311 3.66
M4D2 14 337 3.40 30 325 5.31
M4D3 15 362 5.03 31 344 5.91
M4D4 16 382 5.23 32 369 5.67
Table 16 Table 17
Black Pearl 800/55phd0 N351/33phr/20phr
RSS1 SMRCV RSS1
Code Sample Mw,,, D('/.) Samp/e Mws,, D('/) Code Samp/e Mw,õ, D(%)
No. (K) No. (K) No. (K)
M1 1041 869
M2 786 662 M 1 1300
M3 663 491 M2 803
M4 527 420 M3 601
M1D1 113 507 12.20 129 418 5.15
M1D2 114 551 15.10 130 482 4.94 M1D1 401 854 2.08
M1133 115 700 10.20 131 515 6.93 M1D2 402 969 3.41
M1D4 116 786 5.72 132 583 8.74 M1D3 403 1040 3.68
M201 117 420 5.65 133 403 2.60 M1D4 404 1130 4.91
M2D2 118 441 6.50 134 438 2.74
M2D3 119 549 7.70 135 434 2.83 M2D1 405 648 1.15
M2D4 120 606 5.88 136 530 3.88 M2D2 406 668 2.16
M3D1 121 387 3.26 137 366 2.38 M2D3 407 675 2.98
M302 122 409 2.98 138 378 2.83 M2D4 408 721 4.70
M3D3 123 456 3.61 139 399 3.04
M3D4 124 483 4.61 140 431 2.39 M3D1 409 532 1.10
M4D1 125 339 2.13 141 311 2.22 M3D2 410 537 2.17
M4D2 126 367 2.23 142 332 2.27 M3D3 411 535 2_45
M4D3 127 360 2.60 143 344 2.27 M3D4 412 558 4.06
M4D4 128 403 1.96 144 390 2.73
~l
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Table 1SA
Regal 250155phr/0
RSS1 SMRCV
Code Sample Mw,, DSample Mw,,, D('/)
Na. (K) No. (K)
M1 1332 1023
M2 896 748
M3 603 581
M4 408 504
M101 33 585 6.95 49 609 1.93
M102 34 669 8.03 50 634 3.29
MID3 35 759 10.5 51 681 2.21
M1D4 36 896 14.1 52 702 4.09
M2D1 37 580 2.71 53 539 2.14
M2D2 3B 602 2.61 54 569 2.72
M2133 39 631 3.61 55 587 4.75
M2D4 40 667 5.43 56 595 6.25
M301 41 457 1.53 57 466 2.88
M302 42 476 2.09 58 449 3.19
M303 43 493 2.32 59 464 4.53
M3D4 44 495 3.54 60 500 5.89
M4D1 45 372 1.53 61 423 2.89
M4D2 46 382 2.09 62 433 3.42
M4D3 47 381 2.32 63 437 4.39
M4D4 48 403 3.54 64 447 4.73
Table 188
Regal 250/6510 Regal 250175/0 Regal 250/65/10
RSS1 RSSI RSS1
Code Sample Mw,,, D(%) Sample Mw,,, D('/) Sample Mw,,, D(%)
No. (K) No. (K) No. (K)
M1 1138 1138 1138
M2 901 901 901
M3 660 660 660
M4 483 483 483
M1D1 65 570 1.50 81 539 2.87 97 661 1.89
M1D2 66 622 3.25 82 624 4.50 98 702 2.69
M1D3 67 707 7.50 63 685 4.17 99 741 3.14
M 104 68 788 4.77 84 763 14.35 100 822 5.24
M2D1 69 534 1.62 85 484 4.32 101 593 0.91
M2D2 70 548 4.19 86 512 2.96 102 572 3.48
M2D3 71 585 4.31 87 57 4.71 103 642 4.23
M2D4 72 621 6.21 88 605 4.85 104 664 5.35
M3D1 73 459 3.64 89 429 2.27 105 507 2.65
M3D2 74 469 5.79 90 446 2.68 106 544 2.96
M303 75 511 5.30 91 466 3.46 107 535 3.69
M3D4 76 541 9.13 92 491 6.22 108 524 3.27
M401 77 380 2.34 93 368 2.11 109 416 1.85
M4D2 78 392 2.86 94 372 3.13 110 413 3.18
M4D3 79 399 4.59 95 375 2.92 111 418 6.96
M4D4 80 395 4.57 96 388 2.92 112 441 6.46
52
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Table 19 Table 21(A)
N326155ohr/0 S6740/55ahr/0
RSS1 SMRCV RSS1
Code ampte Mw,.i e ampre w,o, o Code ampie wm, a)
No. (K) No. (K) No. (K)
M 1 1200 1060 M 1 1080
M2 1030 934 M2 837
M3 724 777 M3 724
M4 635 644 M4 532
M1D1 145 550 3.49 161 644 1.15 M1D1 412 515 1.24
M1D2 146 636 3.54 162 661 1.32 M102 413 556 1.32
M1D3 147 650 5.89 163 697 1.35 M1D3 414 633 1.41
M1D4 148 724 4.79 164 732 2.01 MID4 415 732 1.43
M2D1 149 517 3.16 165 590 1.50 M2D1 416 433 0.86
M2D2 150 572 2.41 166 621 1.56 M2D2 417 451 0.90
M2D3 151 613 3.11 167 641 222 M2D3 418 495 1.53
M2D4 152 696 4.37 168 676 2.31 M2D4 419 542 2.15
M3D1 153 489 2.78 169 551 1.22 M3D1 420 405 0.25
M3D2 154 521 1.93 170 550 1.62 M302 421 418 0.50
M3D3 155 504 3.14 171 563 2.06 M3D3 422 447 0.75
M3D4 156 538 2.81 172 578 268 M3D4 423 469 0.73
M4D1 157 415 1.74 173 487 1.96 M4DI 424 371 0.21
M4D2 158 447 2.17 174 495 2.22 M4D2 425 387 0.42
M4D3 159 466 3.13 175 505 2.99 M4D3 426 382 0.30
M4D4 160 469 2.93 176 526 3.37 M4D4 427 396 0.50"
Table 20 Table 21(B)
N110/55phr/0 S6740155nhr/0
RSS1 SMRCV SMRCV
Code ampie Mw,,l . ampre w,,, o Code ampre w,,, o)
No. (K) No. (K) No. (K)
M 1 937 730 M 1 876
M2 764 653 M2 754
M3 569 541 M3 574
M4 449 463 M4 444
M1D1 369 360 1.24 385 334 1.28 M1D1 428 433 0.25
M102 370 426 2.50 386 339 1.60 M1D2 429 441 0.36
M1D3 371 490 2.69 387 372 1.42 M103 430 467 0.34
M1D4 372 618 4.68 388 413 2.80 M1D4 431 540 0.84
M2D1 373 340 0.69 389 309 0.72 M2DI 432 399 0.35
M2D2 374 356 0.85 390 314 1.17 M2D2 433 399 0.41
M203 375 395 0.90 391 342 1.27 M2D3 434 422 0.62
M2D4 376 433 1.17 392 380 2.94 M2D4 435 469 0.44
M301 377 295 0.81 393 271 0.94 M3D1 436 340 0.44
M3D2 378 313 1.27 394 292 0.93 M3D2 437 363 0.81
M3D3 379 333 1.20 395 314 1.43 M3D3 438 377 0.89
M304 380 353 1.35 396 351 1.77 M3D4 439 403 0.86
M4D1 381 255 1.12 397 260 0.74 M4D1 440 363 0.65
M4D2 382 269 1.14 398 267 0.93 M4D2 441 328 1.05
M4D3 383 287 1.30 399 284 1.49 M4D3 442 342 1.52
M4D4 384 316 1.67 400 297 1.83 M4D4 443 360 1.99
53
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Table 22(A)
Regal 660/55phr10
RSS1 SMRCV SMR10
Code Sampie Mw., D a ampre M w.~ a ampre w,,, e
No. (K) No. (K) No. (K)
M1 1110 836 746
M2 844 709 632
M3 609 584 492
M4 522 513 416
M1D1 177 674 8.35 193 564 1.87 209 501 9.54
M 1 D2 178 792 7.89 194 611 2.50 210 572 6.68
M103 179 891 8.53 195 708 3.08 211 681 7.37
M104 180 676 7.46 196 671 2.31 212 594 7.18
M2D1 181 598 8.56 197 520 5.28 213 463 2.82
M202 182 602 3.89 198 558 4.85 214 483 4.57
M2D3 183 697 6.40 199 603 2.88 215 565 3.92
M2D4 184 659 5.71 200 541 4.25 216 550 5.68
M3D1 185 473 2.03 201 486 2.79 217 395 2.13
M302 186 506 1.66 202 482 2.76 218 393 1.98
M3D3 187 562 1.94 203 504 3.54 219 443 2.49
M3D4 188 559 4.33 204 526 2.41 220 449 1.90
M4D1 189 401 2.18 205 415 3.16 221 335 1.49
M4D2 190 426 1.72 206 418 2.92 222 345 1.71
M4D3 191 466 1.48 207 446 2.80 223 363 1.78
M4D4 192 449 3.57 208 465 3.13 224 374 2.35
Table 22(B)
Rega/660/45/0 Regal660/65/0 ~ Re_cal660/65/10
RSS1 RSS1 ~ RSS1
Code ampie w,o, o Sample w,,, o Sample w,,, o
No. (K) No. (K) No. (K)
M1 1245 1245 1245
M2 876 876 876
M3 625 625 625
M4 482 482 482
MID1 225 646 3.45 241 563 14.55 257 639 1.63
M1D2 226 697 3.04 242 638 14.09 258 699 3.55
M 1 D3 227 762 7.70 243 691 13.64 259 814 5.44
M1D4 228 830 6.75 244 790 11.26 260 764 11.25
M2D1 229 574 4.79 245 469 5.88 261 572 2.77
M2D2 230 589 3.02 246 507 7.31 262 580 4.39
M2D3 231 636 6.41 247 558 9.72 263 610 5.51
M2D4 232 675 6.55 248 543 10.59 264 638 7.29
M3DI 233 471 2.66 249 420 5.48 265 474 4.10
M3D2 234 481 5.17 250 426 6.97 266 485 5.72
M3D3 235 510 7.78 251 468 8.81 267 502 624
M3D4 236 518 7.89 252 471 9.55 268 495 7.13
M4D1 237 388 3.20 253 335 5.19 269 390 5.02
M4D2 238 392 5.65 254 344 6.06 270 365 5.88
M4D3 239 397 5.14 255 344 5.59 271 410 7_45
M4D4 240 403 7.54 256 361 8.54 272 388 7.59
54
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Table 23(A)
N234/55phr/0
RSS1 SMRCV SMR10
Code ampte M w~õ e ampte w,,, o ampte w,,, o
No. (K) No. (K) No. (K)
M1 1060 845 743
M2 811 712 621
M3 595 577 445
M4 466 477 388
M1D1 273 350 1.88 289 312 0.61 305 325 0.78
M1D2 274 476 3.40 290 317 0.64 306 363 1.66
MID3 275 459 2.70 291 361 1.03 307 400 1.89
M1D4 276 665 2.70 292 419 1.56 308 459 1.73
M2D1 277 323 0.40 293 304 0.76 309 294 0.54
M2D2 278 371 0.73 294 306 0.72 310 321 1.24
M2D3 279 398 0.74 295 318 0.74 311 354 1.28
M2D4 280 464 1.42 296 357 1.30 312 363 1.39
M3D1 281 278 0.47 297 260 0.53 313 260 0.69
M302 282 304 0.83 ~ 298 272 0.65 314 268 0.48
M3D3 283 323 0.82 299 295 0.58 315 289 1.38
M3D4 284 360 1.06 300 302 1.14 315 303 0.78
M401 285 251 0.61 301 244 0.53 317 236 1.00
M402 266 266 0.51 302 253 0.81 318 239 0.77
M4D3 287 273 0.64 303 266 0.62 319 257 0.72
M4D4 268 282 0.53 304 296 0.88 320 268 1.30
Table 23(B)
N234/45/0 N23416510 N234165/10
RSS1 RSSI RSS1
Code ampte w,,, D(a) ampte Mw,,, o ampte Mw,,, o
No. (Iq No. (K) No. (K)
M1 1185 1185 1185
M2 828 828 828
M3 623 623 623
M4 462 462 462
M101 321 507 7.33 337 336 3.44 353 395 5.51
M102 322 598 8.15 338 458 5.09 354 478 7.68
M103 323 731 8.97 339 479 8.17 355 5:;5 9.46
M104 324 772 12.02 340 706 9.90 356 637 8.39
M201 325 486 3.48 341 255 3.22 357 295 0.58
M2D2 326 479 5.44 342 288 3.34 358 352 1.23
M2D3 327 527 5.51 343 295 4.65 359 394 1.35
M2D4 328 556 7.70 344 393 5.45 360 449 2.37
M301 329 419 0.88 345 237 1.50 361 292 0.86
M302 330 423 1.24 346 252 1.78 362 286 1.14
M3D3 331 431 2.55 347 270 2.88 363 313 2.19
M3D4 332 458 4.03 348 304 3.92 364 340 2.51
M4D1 333 341 0.62 349 226 1.18 365 265 0.83
M4D2 334 338 1.13 350 214 1.81 366 273 0.99
M403 335 319 1.37 351 233 2.97 367 291 1.39
M4D4 336 354 2.06 352 258 3.83 368 307 2.41
CA 02511365 1997-03-25
WO 97136724 PCT/US97105276
Preferred Embodiment Examples
Additional samples of elastomer composites in accordance with the present
invention were prepared. Specifically, a series of natural rubber elastomer
composites no. I - 32 in accordance with the present invention was produced
using
apparatus and procedures generally in accordance with those of Example A
above.
The elastomer composites comprised natural rubber field latex from Malaysia
with
the properties shown in Table 24 below. The elastomer composites each further
comprised carbon black with morphological properties (structure and surface
area)
of Regions I, II or III in Fig. 8. Specifically, the following carbon blacks
were used:
Regal 660, N234, N326, N110, ReQal 250, N330, Black Pearl 800, Sterling
6740 and N351. The carbon black loadinos ranged from 30 to 75 phr, and
extender oil loadings were in an amount from 0 to 20 phr. The production
details for
elastomer composite sample nos. 1- 32 are shown below in Table 25.
As noted above, the apparatus and procedures used to prepare elastomer
composites no. I - 32 were generally in accordance with those of Example A,
including the masterbatch formulation additives shown in Table 2. A more
detailed
description of the apparatus and procedures used for elastomer composites no.
1-
32 is set forth below.
1. Apparatus
Invention samples no. 1- 32 were prepared using masterbatch production
apparatus substantially in accordance with the invention apparatus described
above
with reference to Figs. 1, 4 and 7. The diameter of the slurry nozzle tip (see
item 167
in Fig. 7) and the length of the land (see item 168 in Fig. 7) are given in
Table 25 for
each of samples no. 1- 32. The coagulum zone of the apparatus had four zones
of
progressively larger diameter from the mixing zone to the discharge end. The
diarr :ter and axial length of each of the four zones (the first zone being
partlv within
the r::ix-head and partlv within the extender sealed thereto) are set forth in
Table 25.
There were axially short, faired interconnections between the zones.
56
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WO 97/36724 PCT/US97/05276
2. Carbon Black Slurry Preparation
Bags of carbon black were mixed with deionized water in a carbon black
slurry tank equipped with an agitator, The agitator broke the pellets into
fragments
to form a crude carbon black slurry. The carbon black concentration (as weight
percent) in the carbon black slurry for each of the sample is given in Table
25.
During operation, this slurry was continually pumped by an air diaphragm pump
to
a grinder for initial dispersion. The slurry was then fed via an air diaphragm
pump
to a colloid mill which then fed into a progressing cavity pump to a
homogenizer,
specifically, Microfluidizer Model M210 from Microfluidics International
Corporation. The microfluidizer produced a finely ground slurry. The slurry
flow
= rate from the microfluidizer to the mixing zone was set by the
microfluidizer pressure,
the microfluidizer actine as a high-pressure positive displacement pump.
Slurry flow
rate was monitored with a Micromotion mass flow meter. The pressure at which
the carbon black slurry was fed to the homogenizer and the homoeenizer output
pressure (all pressures are psig) are set forth for each sample in Table 25.
From the
homogenizer the carbon black slurry was fed to an accumulator to reduce any
fluctuation in slurry pressure at the slurry nozzle tip in the mixing zone.
The slurry
nozzle tip pressure and flow rate at which the slurry was fed to the mixing
zone for
each sample are given in Table 25.
3. Latex Delivery
The latex was charged to a 55 gallon feed drum. Antioxidant emulsion was
then added to the latex and mixed in prior to charging. Antioxidants were
added
consisting of tris nonyl phenyl phosphite (TNPP) and Santoflex 134 (alkylaryl
p-
phenvlene diamine mixture) in the amounts shown in Table 25. Each of the
antioxidants was prepared as a 40 wt.% emulsion using 4 parts potassium oleate
per
100 parts antioxidant along with potassium hydroxide to adjust the emulsion to
a pH
of approximately 10. Extender oil, if any, was added in the amount shown in
Table
25. A peristaltic pump was used to move the latex from the feed drum to the
mixing
zone of the coagulum reactor. The latex flow rate and velocity are shown in
Table
25. Latex flow was automatically metered with a Endress + Hauser mass flow
meter.
57
CA 02511365 1997-03-25
WO 97/36724 PCT/US97/05276
The desired carbon black loading was obtained by maintaining proper ratio of
the
latex feed rate to the carbon black slurry feed rate.
4. Carbon Black and Latex Mixing
The carbon black slurry and latex were mixed by entrainina, the latex into the
carbon black slurry. During entrainment, the carbon black was intimately mixed
into
the latex and the mixture coagulated. Soft, wet spongy "worms" of coagulum
exited
the coagulum reactor.
5. Dewatering
The water content of the wet crumb discharged from the coagulum reactor
is shown in Table 25. The wet crumb was dewatered with a dewaterino extruder
(The French Oil Mill Machinery Company; 31h in. diameter). In the extruder,
the wet
crumb was compressed and water squeezed form the crumb and throush a slotted
barrel of the extruder. The final crumb moisture content is shown in Table 25
for
each of the invention samples.
5. Drying and Cooling
The dewatered crumb dropped into a second extruder where it was again
compressed and heated. Water was flashed off upon expulsion of the crumb
through
the die plate of the extruder. Product exit temperature and moisture content
are
shown in Table 25. The hot, dry crumb was rapidly cooled (approximately 20
seconds) to about 100 F by a forced air vibrating conveyor.
58
CA 02511365 1997-03-25
WO 97/36724 PCT/fIS97/05276
Table 24 Natural Rubber Latex Properties
Latex Type Soutce Additives % Dt-%= %Total % Ash Nitt=ogen Volatile
Rubber Solids ppm Fatty
Acid
Concentrate TITI Latex 0.35% NH3 60 62.0 0.15 0.29 0.022
SDN. BHD. ZnO, TMTD
0.1%HHS
Field Latca RRIM', 9/94 0.15% HNS` 28.4 34.2 0.38 0.366 0.052
0_3% NH3,
ZnO, TMTD"
a. RRIM is the Rubber Research Institute of Malaysia
b. ZnO/T'MTD: used for biological preservation, typical 0.025% of 11 mixture
c. HNS: hydroxylamine neutral sulfate, Mooney viscosity stabilizer
59
CA 02511365 1997-03-25
WO 97/36724 PCT/US97/05276
O o o o O O o o o 00 0 00 O o0 00 O o o0 00 00 o o0 o 0 00 00
C O O O O O ~ N o o N u07 N~~' ~ Mo~~ N N~ O O O O ~ O O O
N ~ ~ r r r f~ r r r O r r r r r r ~ r r r r r r r r r
~
. Om
C C
_' O O O O O O O O O O O O O ~ O O O O O O O O O O O ~
N C! O O m O O t0 O t~ ~ O t0 O C) ~ ~ O N O N K) t[~ 4'! Y'~ V) tt) ~f) ~ ~
a .~ ( r f r 7 r t7 N N N N N N N r N N l ' f r N N N N N N N
cm
`
un in &n uo in N un &nirt unNin uo Na w 0 un u~w 0 W~ W)~0 un
2b ~CrrOOOQOrr17OCrGOOOCOrOCGOOOGOOOCi
p a
m_ ^~A Oi C'A ttl tn tl) 1A tn t19 1ff f0 0 0 tCf tA Y9 if) Uf w 0 tn Ill 0 N)
m !O M R) m m Nf P)
` N Nf M N N N N N N N N N N N N N N N N N N N N N N N N N N N N N
~+ O O O O O O O O O O O O O O O O O O O O O O Q O O O O O O O o O
~ y Q o c o ci c a o 0 o a c o o c ca o 0 0 0 0 0 0 0 o c o 0 0 0 0 0 0
a =
lb C o 0 0 0 0 00 o o d o 0 0 0 0 0 0 0 o~ Otn kn tn Ln u~ ~n tCf tn un
a =
m O
w
a)
N K9 N Il] 117 Yf 1A w H7 1A I[) tn tC! Ml tl) tl'I tn fl9 K) tn fl') M tn 0
1') w !'7 m Of qP m t!7
= tn tf) H7 cn tp t~ ap tfl tCf 11) Q fp 0 N9 M) o K) `1r tD CD 1C) Pf Wv t[)
to tp ID w w t0 m
N
O
07 a O O O O J O O O O ~
tn 40 W) to~ tD 07 cO t0 m
e0 V m O O O N N N N m t0 t0 m tD v~f ~f a v a ~t d (~ < Q v v <<~t ~t v
~~ ('~7 M!~~) Q Q Q ~ l'N9 Q Q Q Q N N N N N N N r O') Z N N N N N N C'MV N N
+-zzzoooo -zoooozzzzzzzzz~zzzzzzzzz
W W W W W Y W W W W
~~x Er~ ztr am w
O Q O
~
V m mmma-
m io m io io
..m x x x x x x x x x x x x x x x x x x x x x- x x x x x x``
o m m a~ m o m m d a~ m m d o~ m m d m m m m m m m m m m ~~~~
ao io ~ eo _o eo m m~ io m m ia m ia m_o _ m iv m o io io ea in m m t~ ~ v
c c c t
moV V~'v IDvVV t=~"aV am~v ooovvoo 0 0~ o
a> m n~ m 'm C~ C7 a~ iu a~ a`~ a~ m n~ a~ a~ n~ m m a> a~ V 67 a'~ n`~ m C~
a') t) t) t)
a`o mmmis
= _c2
2 r N!'1 f 1t) fD f~ m Q! d r N ey) ef 1n fD 1~ OD Q1 O r N P) ~ KS m h fD Q)
O r N
~ r r r r r r r r r r N N N N N N N N N N P) CO !'9
CA 02511365 1997-03-25
WO 97/36724 PCT/L1S97/05276
u
NO' OJOOOpO W W NNNtaf'fmmtOaD Of inu7+J', u7 G7¾103 ED
~ = tA S ~ W r r r ~(j ~~ 1~l IA IA Q C~ !~ !r! ~C Q'C ~- K7 `C N7 M M M M N N
N N
N r r r r r r r r r r r r r r r r r r r r r r r r- r
y V r r r r N CM
m U
N N N N N N N N N N N N N N N N N N N N N N N N N N N N N
_ M M m C9 !'0 M!`') C7 !O rf l'q M M M P7 M M M fi M M M M M M!-i M M c'Y M
66
!~ M rf t 1 M e+f M M M!~ e! e~f M M!~7 !h M M M M M M t'1 e~f th !~ M f Y M M
M M M
. t[) 1() ttf tn K) {A K) 47 tA fq L17 K) 1A 1C1 ~l7 w! Y) w) 11) 1n Y7 u'f N~
t!) IA Y7 ln u9 1[) K) U) tCl
0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p Q p p
.~ M M M t0 M M M M lO l7 !9 M M!7 r7 f7 M M M M M M RJ M M M R) M M M M!7
N N N N N N N N N N N N N N N N N N N N N N N N N N N cY N N N N
~'! s MMm Oom m m m m(p CO m 4J 07 00 67 aD a0 C! Oo m ED Qo fA CD 00 OD m m
ED tD Q
.~ C1 M elf ei M M M t7 M t7 l'q M M M M M P7 e0 t0 P~ (9 !O C7 M M C) M h7 t7
(n M M C)
d ~ ~ O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
cN O
C) ~
N o ~~ammmm~amm~om~ammmmmma~~a~oa~m~mmmmm¾,comm
r r r r r r r r r r r r r r r~- r r r r r r r r r r r r ~- r r r
~ U O C
m
N +It~ f~ f~ I~ e~ 1~ 1~ 1~ 1~ 1~ -~ f~ f~ f~ e~ h rn r- -- -~ ti-- r- 1- 1~ r-
-.- -.- -~ r~ 1~ f~
N N N N N N CM CM N N N N N N N N N N N N N N N N N N N N N N N N
!~ O O O O O O O O O O O O O d O O O O O O O O O O O O O O O O O O
O r r O O O O O r r O O O r O p O O O O ~ O O O O O O O O O O O
R) O) M M r.- M 6 M C. C) M M M M M M M P) M M M!? e7 M l'')
~IL" J
.. .. O
M
...... ~+ O~ Qf Q1 W Of Qf Q~ Q> Ci oW Of C~ Q! O7 Cf Ct O~ Of Ci Of O> W o~
Of Qf O~ Qf O~ Of Of Q- W
r r r r r r r r r r r r r r r r r r r r r r r r r r r r !-- r r r
ti O O O O O O O O O O o O O O O O O O O O O O O O O O O O O O O O
CZ.
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r N M'P tf) fp 1~ ED Cf p r N M vtn t0 1.-oD 0 O r N P) et t[f m 1- m Ql O=- N
rr rrrrrrrrNN NNNNNN NNP) P)l~)
N~0
61
CA 02511365 1997-03-25
WO 97/36724 PCT/1JS97/05276
~
Q
OIEDNNI~. (0 U)0 N1- 01CifDM W KtAtrGlml7mQf Nmr(D<rp
n 6 QI CD h 6 6 6 67 ID 1~ r- r- W m CD N e- m m f. 1-~ oD t0 M m m c7
v C
4
'_
Q\~ f~ Of p - aD Ql p p O ID O fD R mv v r YY 0 m r r f- r0 O CD N m M - O
{~r y e m N 0 f0 [I tD <'V' e7 f- <= v NIn p fD 4 R tn H] i0 Y7 tfJ Q'v N N N
N
d
v
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.. =. y~ Q C Q'7 Q' `C Q Q Q Q'C e~ R Q~C e er Q<'P ~t ~ Q~' '~f Q Q ~f R<
y ~ C O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
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M l~ M M M C'f M!7 l~ C") C7 !7 !''f t'7 M t7 P7 M c'7 !'7 c'7 M M P7 f7 !'7 M
M P7 n7 l+9 th
O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
= ~ V
Q V
U o u
QI C D P 1~ ? o 0 0 o m M M r m m o 0 o r m WIV'N9 r V' d' Q Q~T !7 P'9 !O f7
~D j V) f') 'O' Q Q 1~ f~ 1~ m Om A Y7 w m N N N m m m Qf l- mwcP v Qw Otp CD
m
94 ``~') N N Cf P) m F) PY m N P) M!7 Pf w `a= lw P) C7 t') tn tn Ff le Q= Q~C
Q Q
d CC~
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Q^L. iU N N Cp N N N N N ~ r m Q~ M 1- f- f-- N M[7 lh r - r.- r r r M M~7 M
V' m m`C tJ') t[) tn 4=) @ eP 1t7 Q il) N') LI) {1') tCf tt) U) t[) K7 t19 tl7
K) 1[) Ml K) li7 KI {n {(i
q
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ti
O N~ O O tCf O O O O O Y'f O O O O O O uY O O O O O O O O O O O
tA O N N O O-- W O 0 O t- O O O O O N N O 1t) N I- u7 I~ ta t17 min N
~1' 4 Or v if tn ptntn Or m p m M O O O O Ul) gn N N N N N N N N
m r N l'~ O r N c7 4 t17 iD f~ ~D C! O N!+f ~ tff m I~ O Qf O r N
<~ mr` mcn r r - r r r - - r - N N N N N N N N N N f'7 M M
Z 4 ~
62
CA 02511365 1997-03-25
WO 97/36724 PCT/US97/05276
e M N N M N N M N N Q ~19 N Qf ~- '7 Mto N McD M Q f- < mV Of N
~, O O O O O O O O O O O O O O O O O O O O O O O O r- O O O C
V
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~ Y] 0 U) - . M - Q . m M ~ M f~ N tr tl) m M CD Q1 O N 0 fV
~~..~ M Q v M M M M R) N M M~~~ M M M M N M t'f M~ Q tr <~ O O
O O O -W
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a
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d o
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OD QD G1 O
f0 1.: 1- m CO CD ED 'n
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O
.M [O ti f~ Of N Q m l~ Q~ m t~ !~ .- Qf N N N O O Ll'1 N m "0' !, M M7
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MV
f.- 1~ f- r. 1- 1- f-- w fD 1- 1- 1- 1.- 1.- t- -~ N n(~
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O Z
MV Ln i0 1~ ~ Q7 O e~ N <<l9 CD 1~ m Q~ O N
-" N M~~ m~ O O=- .- -.- r- - -.- - - N N N N N N N N N N M M M
L R
~ y
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It should be noted that samples 2 and 3 were produced with approximately no
outlet
pressure at the Microfluidizer outlet, etc., to determine macro-dispersion
under
adverse process conditions.
The excellent carbon black dispersion in the resultant masterbatches is
demonstrated by their macro-dispersion quality and molecular weight of the sol
portion MW.,. Table 26 below shows the MWw, and macro-dispersion values for
invention samples 1- 32, along with the carbon black and oil (if any) used in
each
of the samples. The carbon black loading and oil loading are shown as phr
values
in Table 26.
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Table 26 Sol Molecular Weight and Undispersed Area of Invention Samples
Invention Sample No. CB/Loading/Oil Mw,,, (K) D( /,)
1 N330/5510 305 0.26
2 N33015510 726 0.54
3 N330/55/0 544 0_40
4 R250155/0 876 0.08
R25016510 670 0.16
6 R250175/0 655 0.03
7 R250165/10 519 0.02
8 8P800155/0 394 0.14
9 N326155/0 666 0.20
R660155/0 678 0.12
11 R660/4510 733 0.05
12 R660/65/0 568 0.04
13 R660/65110 607 0.02
14 N23415510 433 0.15
N23415510 1000 0.10
16 N23415510 500 0.15
17 N234/5510 550 0.10
18 N234145/0 495 0.17
19 N234/65/0 359 0.20
N234165/10 350 0.11
21 N 110155/0 612 0.17
22 N351/33/20 800 0.10
23 S6740155/0 630 0.10
24 N234/48/5 509 0.05
N234/5315 485 0.12
26 N234158/5 447 0.12
27 N234/63/5 403 0.13
28 N234/68/5 378 0.16
29 N23414915 618 0.12
N234/54/5 482 0.16
31 N234/63/5 390 0.17
32 N234165/5 325 0.20
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The results for all invention samples having carbon black loading of 55 phr
are shown
in the semi-log slot of Fig. 9 along with macro-dispersion and MW., values for
a
corresponding series of the above described natural rubber control samples
produced
by dry mixing techniques. At least one data point for an invention sample
comprising
55 phr loading of each carbon black is shown in Fig. 9, along with all of the
control
samples having carbon black loading of 55 phr. (Control samples 401 to 412,
also
shown in Fig. 9, used 33 phr N351 carbon black and 20 parts extender oil.) It
can
be seen in Table 26 and in Fig. 9 that the invention samples have excellent
macro-
dispersion. Specifically, the invention samples have D(%) values generally
below
0.2%, even at MWso, values above .85 x 106 whereas the control samples never
achieve such excellent macro-dispersion at any MWso,. Thus, the data shown in
Fig.
9 clearly reveals that the macro-dispersion quality of the novel elastomer
composites
over a wide range of MW., values is significantly superior to that achievable
using
comparable inQredients in prior-known dry mixing methods. The symbols used for
the various data points shown in Fig. 9 and those used in subsequently
discussed Fias.
10 - 25 are explained in the leaends below.
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Figure Captiopns
Figure 9 Dispersion Quaiity and MW Sol of NR Masterbatches
x control samples 177 to 224
= controi samples 273 to 320
+control samples 145 to 176
p control samples 369 to 400
p control sampies 33 to 64
Xcontrol samples 1 to 32
o control samples 113 to 144
o control sampies 412 to 443
=control samples 401 to 412
^ invention samples
Figure10 Dispersion Quality and MW Sol of NR Masterbatches
(Region 1) x control samples 177 to 224
.,co invention sample 10
e! control samples 145 to 176
:: inventlon sample 9
o control samples 33 to 64
O inventfon sample 4
K control samples 1 to 32
.~ invention sample 1
= controt samples 113 to 144
^ invention sample 8
Figure 11 Dispersion Quality and MW Sol of NR Masterbatches
(Region !1)
A control samples 273 to 320
^ invention sample 14
e control samples 369 to 400
p invention sample 21
Figure 12 Dispersion Quality and MW Sol of NR Masterbatches
(Region 111) = controt samples 401 to 412
^invention sample 22
o control samples 412 to 443
p invention sampie 23
Figure 13 Dispersion Quality and MW Sol of NR Masterbatches
(N330 Carbon Black, 55 phr)
= control samples 1 to 32
^ invention sampies 1 to 3
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Fiaure 14 Dispersion Quality and MW Sol of NR Masterbatcnes
(REGAL 250 Carbon Black)
= convol samples 33 to 64
^ invention sample 4
o control sample 65 to 80
a invention sample 5
o control sampies 81 to 96
e invention sampie 6
= control samples 97 to 1121
= invention sample 7
r:igure 15 Dispersion Quality and MW Sol of NR Masterbatches
(BLACK PEARL 800 Carbon Black, 55 phr)
.......... -= = ccntrot sampfes 113 to 144
^ invention sample 8
FiQure 16 Dispersion Quality and MW Sol of NR Masterbatches
(N326 Carbon Black, 55 phr)
= control samples 145 to 1761
^ invention sample 9
F=igure 17 Dispersion Quality and MW sol of NR Masterbatches
(REGAL 650 Carbon Black)
= conual samples 177 to 224
^ invention sample 10
p control samples 225 to 240
p invention sample 11
o control samples 241 to 256
invention sample 12
= control samples 257 to 272
A invention sample 13
Figure 18 Dispersion Quality and MW sol of NR Masterbatches
( N234 Carbon Black)
9 control samples 273 to 320
^ invention samples 14 to 17
o control samples 337 to 352
p invention sample 19
o control samples 321 to 336
p invention sample 18
= control samples 3-1-53 to 368
= invention sample 20
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Fioure 19 Disoersion Quality and MW Sol of NR Masterbatches
(N110 Carbon Black, 55 phr)
= control samples 369 to 400 i
^ invention sample 21
Figure 20 Dispersion Quality and MWsol of NR Masterbatch
( N351 Carbon Black, 33 phr)
o rconu-ol sampies 401 to 412
^ invention samole 22
Figure 21 Dispersion Quality and MW Sol of NR Masterbatches
(STERLING 6740 Carbon Btack, 55 phr)
0 cpnvol samples 412 to 443
a invention sample 23 I
Figure 22 MW sol Effect on Crack Growth Rate
(NR Compounds Containing N234 Carbon Black 55 phr Loading)
*control sampies 273 to 288
p inventon sample 16
Fioure 23 MW sol Effect on Crack Growth Rate
(NR Compounds Containing N326 Carbon Black @ 55 phr Loading)
9 control samples 145 ta 160
o invention sample 9
Fiaure 24 MW sol Effect on Crack Growth Rate
(NR Compounds Containing REGAL 660 Carbon Black c@ 55 phr Loading)
= controi samples 177 to 192
p invention sample 10
Fioure 25 Max. Tan 6(Strain Sweep @60 C) of NR Compounds Containing N234 Black
at Different Loadinas
= invention samples 24 to 2B
o invention sampies 29 to 32
t3 control sample 444 to 450
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Figure Captiopns
Fioure 30 Macro-dispersion Quality and MW of Sol Portion of NR Masterbatch
Containing Dual Phase (Carbon Black/Silica) Aggregates
= control samples 451 to 458
^ invention sample 33
o control sampies 459 to 466
c: invention sample 34
Figure 31 Macro-dispersion Ouaiity and MW of Sol Portion of NR Masterbatch
Containing Blend of Carbon Black and SiGca
= control samples 491 to 498
^ invention sample 38
o control samples 483 to 490
o invention sample 37
o control samples 475 to 482
o invention sample 36
s controt samples 467 to 474
->s-invention sample 35
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The macro-dispersion values for the elastomer composites of the invention
shown in Fig. 9 are described by the following equations:
D (%) < 0.2% (1)
when MW., is less than 0.45 x 106; and
log (D) < log (0.2) + 2.0 x[MWSO, - (0.45 x 106)] x 10-6 (2)
when 0.45 x 106 < MW., < 1.1 x 106.
It will be recognized from the discussion above, that macro-dispersion D (%)
in
the above equation (1) is the percent undispersed area measured for defects
¾reater than 10 microns. It can be seen in Fig. 9 that D(%) equal to 0.2% is
the
threshold macro-dispersion quality for all carbon blacks in Regions I, II and
III for
natural rubber dry masterbatches. That is, none of the dry masticated
masterbatches achieved macro-dispersion quality of 0.2% at any MW,.,, even
after mixing sufficiently to degrade MWto, below 0.45 x 106, as described by
equation (1) above. When the MW., of the dry masterbatch control samples
shown in Fig. 9 is between 0.45 x 106 and 1.1 x 106, the dispersion quality is
even
poorer while, in contrast, the dispersion quality of the invention samples
having
MWw in that range remains excellent. None of the preferred embodiments shown
in Fig. 9 having MWs,, between 0.45 x 106 and 1.1 x 106 exceeds the preferred
macro-dispersion limit of 0.2%. In that regard, it should be understood that
the
data points for preferred embodiments which are seen in Fig. 9 (and in other
Figures discussed below) to lie on the X axis (i.e:, at D(%) value of 0.1%)
may
have macro-dispersion quality of 0.1% or an even better (i.e., lower) D(%)
value.
Region I Carbon Black Samples
Invention samples comprising carbon blacks having morphological properties
(i.e., structures and surface area) of Region I in Fig. 8, and corresponding
control
samples described above made with such Region I carbon blacks, are compared in
the
semi-log plot of Fig. 10. Specifically, Fig. 10 shows the macro-dispersion
values and
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MW,, values of the invention samples and corresponding control samples
comprising
the carbon blacks Regal 660, N326, Regal 250, N330, and Black Pearl 800, at
carbon black loading ranging from 30 phr to 75 phr and extender oil loading
ranging
from 0 phr to 20 phr. Excellent carbon black dispersion is seen in Fig. 10 for
all of
the invention samples, representing preferred embodiments of elastomer
composites
in accordance with the present disclosure. All of the invention samples
advantaeeously are below line 101 in Fig. 10, whereas all of the control
samples have
poorer dispersion, being above line 101. In fact, the preferred embodiments
shown
in Fig. 10, even through comprising carbon blacks from Region I, the most
difficult
to disperse, all fall below a D(%) value of .3%. The most preferred
embodiments 0
have a D(%) value not exceeding .2% even at an MW,., value advantaeeously
exceeding .7 x 106. The data shown in Fig. 10 clearly reveals that the macro-
dispersion quality of the novel elastomer composites disclosed here comprising
Region I carbon blacks, over a wide range of MW,., values, is significantly
superior
to that achievable using comparable ingredients by prior dry mastication
mixing
methods. The macro-dispersion values for the elastomer composites of the
invention
shown in Fig. 10 are described by the following equations:
D(%) < 1.0% (3)
when MW,., is less than 0.7 x 106; and
log D < log (1.0) + 2.5 x[MWSO, - (0.7 x 106)] x 10'6 (4)
when 0.7 x 106 < MW", < 1.1 x 10G
It will be recognized that D (%) is the percent undispersed area measured for
defects ereater than 10 microns and 1% is the threshold macro-dispersion
quality
for all carbon blacks in Region I for natural rubber masterbatches in
accordance
with the present invention. That is, none of the dry masticated masterbatches
achieved macro-dispersion quality of 1.0% or better at any MWSO, , even after
dry
mixing sufficiently to degrade MW,., below. .7 x 106, as described by Equation
(3)
above. When the MWso, of the dry masterbatch control samples shown in Fig. 10
is between 0.7 x 106 and 1.1 x 106, the dispersion quality is even poorer. In
contrast, the dispersion quality of the invention samples having MW,., in that
range remains excellent. The preferred embodiment shown in Fig. 10 having
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MWso, between.7 x 106 and 1.1 x 106 falls well below the preferred macro-
dispersion limit of.2%. It can be seen that the elastomer composites of the
invention comprising carbon blacks from Region I provide heretofore unachieved
balance between macro-dispersion quality and MW,., .
Region II Carbon Black Samples
Invention samples comprising carbon blacks having morphological properties
(i.e., structure and surface area) of Region II in Fig. 8, and corresponding
control
samples described above made with such Region II carbon blacks are compared in
the semi-log plot of Fig. 11. Specifically, Fig. 11 shows the macro-dispersion
values
and MVV,o, values of the invention samples and corresponding control samples
comprising the carbon blacks N234 and N110 at carbon black loading ranging
from
40 phr to 70 phr and extender oil loading ranaing from 0 phr to 10 phr.
Excellent
carbon black dispersion is seen in Fig. 11 for all of the invention samples,
representing preferred embodiments of elastomer composites in accordance with
the
present disclosure. The invention samples advantageously are below line 111 in
Fig.
11, whereas all of the control samples have poorer dispersion, being above
line I 11.
In fact, the preferred embodiments shown in Fig. 11 comprising carbon blacks
from
Region II fall below a D(%) value of.3%. Most preferred embodiments have a
D(%)
value not exceeding .2% at any MWai value. The data shown in Fig. 11 clearly
reveal that the macro-dispersion quality of the novel elastomer composites
disclosed
here comprising Region II carbon blacks, over a wide ranee of MW,,, values, is
sienificantly superior to that achievable using comparable ingredients in
prior dry
mixing methods. The macro-dispersion values for the elastomer composites of
the
invention shown in Fig. 11 are described by the following equations:
D(%) < 0.3% (5)
when MW,o, is less than 0.35 x 106; and
log D< log (0_3)12.8 x[MW., -(.35 x 106)] x 10' (6)
when 0.35 x 106 < MW,., < 1.1 x 106.
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It will be recognized that D (%) of .3 0% is the threshold macro-dispersion
quality for
all carbon blacks in Region II for natural rubber masterbatches in accordance
with the
present invention, and 0.35 x 106 is the threshold MW,, value. That is, none
of the
dry masterbatches achieved macro-dispersion quality of 0.30% or better at any
MW.,
even after dry mixing sufficiently to degrade MW., below .35 x 106, as
described by
Equation (5) above. When the MWs,, of the dry masterbatch control samples
shown
in Fig. 11 is between 0.35 x 106 and 1.1 x 106, the dispersion quality is even
poorer.
In contrast, the dispersion quality of the invention samples having MW., in
that range
remains excellent. The preferred embodiments shown in Fig. 11 having MW.,
between.35 x 106 and 1.1 x 106 fall well below the preferred macro-dispersion
limit
of .2%. It can be seen that the elastomer composites of the invention
comprising
carbon blacks from Region 11 provide heretofore unachieved balance between
macro-
dispersion quality and MWs,, -
Region III Carbon Black Samples
Invention samples comprising carbon blacks having morphological properties
(i.e., structures and surface area) of Region III in Fig. 8, and corresponding
control
samples described above made with such Region III carbon blacks are compared
in
the semi-log plot of Fig. 12. Specifically, Fig. 12 shows the macro-dispersion
values
and I~IWSO, values of the invention samples and corresponding control samples
comprising the carbon blacks N351 and Sterling 6740, at carbon black loading
ranging from 30 phr to 70 phr and extender oil loading ranging from Ophr to 20
phr.
Excellent carbon black dispersion is seen in Fig. 12 for all of the invention
samples,
representing preferred embodiments of elastomer composites in accordance with
the
present disclosure. All of the invention samples advantageously are below line
121
in Fig. 12, whereas all of the control samples have poorer dispersion, being
above line
121. In fact, the preferred embodiments shown in F: 12, comprising carbon
blacks
from Reaion III, fall at or below a D(%) value ot.1%, even at an MWsa, value
advantageously exceeding .3 x 106 and even .7 x I(Y . The data shown in Fig.
12
clearly reveals that the macro-dispersion quality of the novel elastomer
composites
disclosed here comprising Resion III carbon black, over a wide range of MW.,
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values, is significantly superior to that achievable using comparable
ingredients in
prior dry mixing methods. The macro-dispersion values for the elastomer
composites
of the invention shown in Fig. 12 are described by the following equations:
D(%) < 0.1% (7)
when MW., is less than 0.35 x 106; and
log D < log (0.1) + 2.0 x[MW,., -(0.30 x 106) x 10-6] (8)
when 0.30 x 106 < MWsoi < I.1 x 106.
It will be recognized that D (%) of 0.1 % is the threshold macro-dispersion
quality
for all carbon blacks in Re¾ion III for natural rubber masterbatches in
accordance
with the present invention, and 0.3 x 106 is the threshold MW'., value. That
is,
none of the dry masterbatches achieved macro-dispersion quality of.1 % at any
MW.,, even after dry mixing sufficiently to degrade MWfo, below .35 x 106, as
described by Equation (7) above. When the MW., of the dry masterbatch control
samples shown in Fig. 12 is between 0.30 x 106 and 1.1 x 106, the dispersion
quality is even poorer. In contrast, the dispersion quality of the invention
samples
having MW.i in that range remains excellent. The preferred embodiments shown
in Fig. 12 having MWso, between .30 x 106 and 1.1 x 106 fall well below the
preferred macro-dispersion limit of .2%, and, in fact, are at or below D(%)
value
of 0.1 %. It can be seen that the elastomer composites of the present
invention
comprising carbon blacks from Region III provide heretofore unachieved balance
between macro-dispersion quality and MW., .
Additional Sample Comparisons
The macro-dispersion values for the invention samples are shown graphically
in the semi-long plots of Figs. 13 through 21, as a function of their MW:o,
values, as
in Figs. 8 through 12 discussed above. More specifically, in Figs. I3 throueh
21 all
invention samples described above comprisinc, a particular carbon black (being
limited
to those of a specific carbon black loading when so indicated) are shown
together in
a single semi-log plot together with the corresponding control samples. (See
the
CA 02511365 1997-03-25
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legends above giving the reference numbers of the invention samples and
control
samples included in each figure.) Thus, Fig. 13 shows the dispersion quality
and
MW,o, of invention and control samples described above comprising 55 phr N330
carbon black. The data shown in Fig. 13 clearly reveals that the macro-
dispersion
quality of the novel elastomer composites of the invention, comprising N330
carbon
black, over a wide range of NIW, values, is significantly superior to that of
the
control samples. Macro-dispersion for elastomer composites of the invention
comprising N330 carbon black, as shown in Fig. 13 is described by the
following
equations:
D(%) < 1% (9)
when MWso, < 0.6 x 106; and
log (D) < log (1) + 2.5 x[MW., -(0.6 x 106)] x 10' (10)
when 0.6 x 106 < MW.i < 1.1 x 106.
None of the dry masticated masterbatches achieved macro-dispersion quality of
1.0% at any MW.,, even after dry mixing sufficiently to degrade MW.i below 0.6
x 106 (see Equation 9, above). In control samples comprising 55 phr N330
carbon
black in which the MW., was maintained between 0.6 x 106 and 1.1 x 106, the
D(%) value is even higher, such as more than 4% undispersed area.
Fig. 14 shows the dispersion quality and MW,o, of the invention and control
samples described above comprising REGAL 250 carbon black. Selected invention
and control samples shown in Fig. 14 comprised oil, as set forth above. The
data
shown in Fig. 14 clearly reveals that the macro-dispersion quality of the
novel
elastomer composites of the invention comprising REGAL 250 carbon black, over
a wide range of MW,,, values, is sianificantly superior to that of the control
samples.
The macro-dispersion values for the elastomer composites of the invention
comprisine REGAL 250 carbon black, as shown in Fig. 14 are described by the
following equations:
D(%) < 1% (9)
when MW., < 0.6 x 106 ; and
log (D) < log (1) + 2.5 x[MW., - (0.6 x 10')] x 10' (10)
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when 0.6 x 106 < MW,., < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 1.0% or
better at
any MW.,, even after dry mixing sufficiently to degrade MW,., below 0.6 x 106.
In
contrast, elastomer composites of the invention comprising Regal 250 carbon
black
and having MW,,o, above 0.6 x 106 have excellent macro-dispersion, such as
D(%) less
than 0.2%. Compound properties and performance characteristics for the
invention
and control samples shown in Fig. 14, comprising REGAL 250 carbon black, are
set forth in Table 27 below. It can be seen that invention sample No. 4 has
exceptionally good resistance to crack growth, as indicated by its very low
crack
growth rate value of only 0.92 cm/million cycles. In fact, the invention
sample is far
superior to the corresponding control samples. This is believed to be due
largely to
the better MW~, and macro-dispersion of carbon black in the invention sample,
as
discussed above.
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Table 27 Compound Properties of NR Compounds
Containing REGAL 250 Carbon l3lack at 55 phr Loading
Sample No. Mooney Haridness E100 E300 Tensile E3
IML(1+4)@IOOC (ps() (psf) (Psi)
convoi 33 60.63 55.35 18126 999.82 4090.24 675.0
control34 73.58 57.80 235.14 1293.88 3978.24 595.0
controi 35 81.49 58.65 243.66 1265.26 4103.41 613.0
conuo136 84.04 59.95 244.23 1215.87 3960.32 614.0
control 37 57.35 56.75 218.70 1259.99 4119.85 502.0
control38 60.10 57.05 216.75 1206.60 4023.65 620.0
conuol39 68.28 57.25 225.44 1256.23 4134.06 621.0
controi 40 77.40 59.10 255.15 1330.87 4059.01 597.0
convol41 44.40 56.25 216.00 1214.78 4038.68 618.0
control42 47.96 56.50 214.53 1202.93 3944.05 613.0
control 43 49.84 57.05 221.26 1229.07 4018.24 611.0
control44 50.10 56.60 210.50 1140.90 4058.33 638.0
controf 45 36.82 52.90 177.47 982.86 3790.56 533.0
controi 46 38.23 54.50 198.63 1111.04 3860.56 629.0
control47 35.35 54.60 199.03 1110.00 3871.49 505.0
control 48 40.58 55.50 204.52 1139.94 3961.06 632.0
inventon 4 71.97 57.00 218.18 1230.30 4036.30 611.0
Sampie No. Rebound Crack Growth Rate Abrasion loss Tan 6 Tan 6
(cm/miiRon cycles) (g) @ 0=C @ 60'C
convol33 64.50 2.00 0.191 0.167 0.091
control 34 64.55 1.83 0.182 0.155 0.083
contro! 35 63.75 2.38 0.192 0.150 0.091
contro136. 63.30 1.42 0.180 0.162 0.091
control 37 ' 64.65 3.00 0.168 0.176 0.100
control 38 63.45 2.99 0.163 0.184 0.099
conttol39 63.90 2.17 0.186 0.170 0.092
control 40 62.30 1.69 0.182 0.175 0.093
conrrol41 64.20 2.84 0.190 0.189 0.102
control 42 64.20 3.24 0.182 0.168 0.103
control 43 64.50 3.52 0.177 0.183 0.101
control 44 63.90 3.50 0.179 0.185 0" 104
control 45 63.80 3.86 0.199 0.197 0.104
cantrol46 64.30 3.94 0.191 0.184 0.107
control 47 64.35 3.81 0.192 0.106
control 48 63.65 3.46 0.180 0.182 0.110
inventnon 4' 64.70 0.92 0.190 0.148 0.096
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Fig. 15 shows the dispersion quality and MW., of the invention and control
samples described above comprising BLACK PEARL 800 carbon black at 55 phr
loading. The data shown in Fig. 15 clearly reveals that the macro-dispersion
quality
of the novel elastomer composites of the invention comprising Black Pearl 800
. carbon black, is significantly superior to that of the control samples. The
macro-
dispersion values for elastomer composites of the invention comprising Black
Pearl
800 carbon black, as shown in Fig. 15, are described by the following
equations:
D(%) < 1.5% (11)
when MW,., < 0.65 x 106 ; and
log (D) < log (1.5) + 2.5 x[MW~, -(0.65 x 106)J x 10-6
(12)
when 0.65 x 106 < MW., < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 1.0% or
better at
any MW.,, even after dry mixing sufficiently to degrade MW,., below 0.65 x
106. In
contrast, elastomer composites of the invention comprising Black Pearl 800
carbon
black and having MW,a, above 0.65 x 106 have excellent macro-dispersion, such
as
D(%) less than 0.2%. Compound properties and performance characteristics for
the
invention and control samples shown in Fig. 15, comprising Black Pearl 800
carbon
black, are set forth in Table 28 below. It can be seen that invention sample
No. 8 has
exceptionally good resistance to crack growth, as indicated by its very low
crack
growth rate value of only 0.27 cm/million cycles. In fact, the invention
samples are
far superior to the corresponding control samples. This is believed to be due
largely
to the better MWm, and macro-dispersion of carbon black in the invention
sample, as
discussed above.
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Table 28 Compound Properties of NR Compounds
Containing BLACK PEARL 800 Carbon Black at 55 phr Loading
Sample No. Mooney Hardness E100 E300 Tensile EH
ML(1+4)@100C (psi) (psi) (psi) ('/o)
canuol113 110.5 66.4 345.0 1333.0 3878.0 598
contrnl114 109.0 67.3 367.0 1427.0 4033.0 606
control115 106.4 67.2 363.0 1311.0 3896.0 610
control 116 105.7 69.0 322.0 1202.0 3856.0 626
control 117 110.6 67.1 316.0 1400.0 4180.0 616
control 118 118.9 67.1 310.0 1395.0 3967.0 607
convol119 111.9 67.7 309.0 1323.0 4149.0 634
contro1120 110.6 67.6 373.0 1188.0 4199.0 653
control121 114.7 66.3 287.0 1262.0 4329.0 667
control122 110.6 65.8 288.0 1223.0 4217.0 659
control 123 115.0 67.5 280.0 1282.0 4071.0 624
contro1124 116.5 66.5 309.0 1388.0 4166.0 623
contro1125 113.4 65.4 281.0 1274.0 3978.0 631
control 126 101.4 66.8 280.0 1222.0 4206.0 656
control 127 105.5 66.4 262.0 1150.0 4167.0 670
control 128 110.7 66.8 292.0 1301.0 4209.0 643
inven6on 8 131.3 62.5 227.0 1291.0 3418.0 532
Sample No. Rebound Crack Growth Rate Abrasion toss Tan b Tan 6
(cmlmiilion cycies) (g) @ 0=C @ 60=C
control 113 44.7 3.14 0_ 148 0.281 0.184
control 114 45.0 2.72 0.125 0.274 0.185
control115 47.0 2.54 0.163 0233 0.171
control 116 46.6 2.41 0.194 0.244 0.163
contro1117 40.9 4.56 0.086 0.327 0.214
conttoi 118 41.8 2.80 0.112 0.335 0.225
control 119 41.7 4.33 0.091 0.321 0.216
contro1120 42.1 3.89 0.095 0.301 0.207
controi 121 39.2 3.38 0.075 0.312 0.256
conrrol122 38.7 4.58 0.108 0.344 0.236
control 123 40.2 4.79 0.103 0.329 0.232
control 124 41.7 3.78 0.102 0.321 0.209
contnm1125 38.9 3.40 0.076 0.352 0.248
control 126 38.1 5.57 0.070 0.355 0.241
contro1127 38.2 4.79 0.073 0.346 0.254
control 128 39.4 3.40 0.113 0.357 0.23
invention 8 44.8 0.27 0.130 0.297 0.199
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Fig. 16 shows the dispersion quality and MW., of the invention and control
samples described above comprising N326 carbon black at 55 phr loading. The
data
shown in Fig. 16 clearly reveals that the macro-dispersion quality of the
novel
elastomer composites of the invention comprising N326 carbon black is
significantly
superior to that of the control samples. The macro-dispersion values for the
elastomer composites of the invention comprising N326 carbon black, as shown
in
Fig. 16, are described by the following equations:
D(%) < 1% (13)
when MW,., < 0. 7 x 106 ; and
log (D) < log (1) + 2.5 x[MW., - (0.7 x 106)] x 101 (14)
when 0.7 x 106 < MW~., < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 1.0% or
better at
any MW,.,, even after dry mixing sufficiently to degrade MW,o, below 0.7 x 106
In
contrast, elastomer composites of the invention comprising N326 carbon black
and
having MW., above 0.7 x 106 have excellent macro-dispersion, such as D(%) not
greater than 0.2%. Compound properties and performance characteristics for the
invention and control samples shown in Fig. 16, comprising N326 carbon black
are
set forth in Table 29 below. It can be seen that invention sample No. 9 has
exceptionally good resistance to crack growth, as indicated by its very low
crack
growth rate value of only 0.77 cm/million cycles. In fact, the invention
sample is far
superior to the corresponding control samples. This is believed to be due
largely to
the better Iv1W., and macro-dispersion of carbon black in the invention
sample, as
discussed above.
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Tabie 29 Compound Properties of NR Compounds
Containing N326 Carbon Black at 55 phr Loading
Sample No. Mooney Hardness E100 E300 Tensile E3
ML(1+4)(dN00=C (psi) (psi) (psi) ( /=)
control 145 64.6 60.5 289 1713 3921 548
control 146 88.2 62.4 340 1802 4094 553
contmi 147 91.7 63.3 391 1917 3991 528
control 148 96.8 64.3 326 1664 4045 572
control 149 62.4 61.5 310 1763 4029 552
contro1150 67.7 62.6 326 1855 4055 551
control 151 76.5 60.6 287 1641 4015 575
control 152 79.4 63.6 329 1720 3980 559
control153 57.2 60.1 282 1623 3968 579
control 154 57.2 62.8 354 1889 3879 525
control155 57.3 62.2 323 1763 3975 556
control156 60.1 61.9 310 1667 3918 564
control 157 45.1 61.2 328 1748 3768 533
control 158 50.1 60.6 315 1740 3817 546
control 159 53.2 61.3 306 1675 3886 563
control 160 50.5 62.6 331 1752 3884 549
invention 9 77.8 60.9 277 1563 4167 593
Sample No. Rebound Crack Growth Rate Abrasion loss Tan 6 Tan b
(cmlmiHion cycles) (g) @ 0'C @ 60=C
cantrol145. 57.8 2.84 0.0952 0.225 0.129
control146 58.1 2.52 0.0887 0.217 0.126
control 147 57.6 2.03 0.0946 0.205 0.123
control 148 56.3 1.63 0.0927 0?21 0.129
control 149 57.2 3.39 0.0827 0.234 0.142
contro1150 56.8 2.77 0.0866 0.234 0.150
control 151 55.6 2.61 0.0933 0.241 0.149
control 152 54.5 2.79 0.0857 0.249 0.155
contral153 55.4 3.12 0.0911 0.258 0.170
cantral154 56.0 3.35 0.0858 0.241 0.147
control 155 55.4 3.63 0.0811 0.254 0.152
control 156 54.9 3_55 0.0906 0.261 0.153
control157 55.5 3.02 0.0931 0.254 0.149
control 158 55.4 3.81 0.0914 0.249 0.150
control 159 54.9 3.23 0.0933 0.240 0.158
control 160 55.2 3.19 0.0942 0.246 0.163
invention 9 58.4 0.77 0.0939 0.225 0.136
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Fig. 17 shows the dispersion quality and MW,o, of the invention and control
samples described above comprising REGAL (trademark) 660 carbon black.
Selected invention and control samples shown in Fig. 17 comprised oil, as set
forth
above. The data shown in Fig. 17 clearly reveals that the macro-dispersion
quality
of the novel elastomer composites of the invention comprising REGAL 660
carbon
black, over a wide range of MW., values, is significantly superior to that of
the
control samples. The macro-dispersion values for the elastomer composites of
the
invention comprising REGAL 660 carbon black, as shown in Fig. 17 are
described
by the following equations:
D(%) < 1% (15)
when MW., < 0.6 x 106 ; and
log (D) < log (1) + 2.5 x[MWSO, - (0.6 x 106)] x 101 (16)
when 0.6 x 106 < MWso, < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 1.0% or
better at
any MW.,, even after dry mixing sufficiently to degrade MW., below 0.6 x 106=
In
contrast, elastomer composites of the invention comprising Regal 660 carbon
black
and having MW,, above 0.6 x 106 have excellent macro-dispersion, such as D(%)
less
than 0.2%. Compound properties and performance characteristics for the
invention
sample No. 10 and various control samples shown in Fig. 17, comprising Regal
660
carbon black, are set forth in Table 30 below. It can be seen that invention
sample
No. 10 has exceptionally good resistance to crack growth, as indicated by its
very
low crack growth rate value of only 0.69 cm/million cycles. In fact, the
invention
samples are far superior to the corresponding control samples. This is
believed to be
due largely to the better MWm, and macro-dispersion of carbon black in the
invention
sample, as discussed above.
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Table 30 Compound Properties of NR Compounds
Containing REGAL 660 Carbon Black at 55 phr Loading
Sampie No. Mooney Hardness E100 E300 Tensile EB
I ML(1+4) 100'C (psi) (psi) (psi) (%)
control 177 61.0 213 942 702
convol178 87.6 63.2 232 943 4002 694
control 179 87.1 64.9 285 1134 4016 644
contro1180 85.6 64.0 271 1198 4058 618
control 181 80.1 61.0 206 945 4098 661
corttrol182 93.4 59.0 192 835 3924 733
controt 183 89.0 61.0 215 920 4134 698
contto1184 83.4 62.4 223 996 4236 694
controi 185 70.1 60.0 178 794 3768 717
control186 69.8 60.3 196 920 4051 666
control 187 76.7 63.5 166 866 4157 720
control 188 72.1 62.0 191 883 4182 704
control 189 54.3 61.2 222 1079 4240 674
contro1190 557 61.1 193 942 4125 692
control 191 65.0
control192 61.1 60.4 191 902 4189 710
invention 10 88.1 62.9 249 1202 4292 634
Sample No. Rebound Crack Growth Rate Abrasion [oss Tan 6 Tan 8
(cm/million cycles) (g) @ 0=C @ 60=C
control177 54.6 0.131
control 178 55.6 2.34 0.1649 0.194 0.129
convol179 53.7 2.78 0.1620 0.200 0.140
contro1180 52.9 2.98 0.1385 0.220 0.153
control 181 51.0 3.41 0.1189 0.267 0.185
control 182 49.9 3.11 0.1076 0.270 0.194
controi 183 50.1 3.15 0.1086 0.264 0.192
control 184 48.0 3.11 0.1085 0.284 0.208
contro1185 47.5 4.59 0.0937 0.306 0.209
concrol186 48.5 4.06 0.1008 0.295 0.211
contro1187 47.7 3.53 0.1041 0.297 0.198
control 188 47.8 3.79 0.0985 0.285 0.207
control 189 47.5 3.71 0.0957 0.306 0.203
control190 46.8 4.14 0.0962 0.300 0.200
control 191 47.4 0.226
contrnl192 46.5 4.78 0.0897 0.301 0.226
invention 10 48.2 0.69 0.0942 0.271 0.178
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Fig. 18 shows the dispersion quality and MW,,,, of the invention and control
samples described above comprising N234 carbon black. Selected invention and
control samples shown in Fig. 18 comprised oil, as set forth above. The data
shown
in Fig. 18 clearly reveals that the macro-dispersion quality of the novel
elastomer
5. composites of the invention comprising N234 carbon black, over a wide range
of
MW,,, values, is significantly superior to that of the control samples. The
macro-
dispersion values for the elastomer composites of the invention comprising
N234
carbon black, as shown in Fig. 18 are described by the following equations:
D(%) < 0.3% (17)
when MW,,, < 0.35 x 106 ; and
log (D) < log (0.3) + 2.8 x[MVJ:o, -(0.35 x 106)) x 10-6 (18)
when 0.35 x 106 < MW., < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 0.3% or
better at
any MW,o;, even after dry mixing sufficiently to degrade MWso, below 0.35 x
106- In
contrast, elastomer composites of the invention comprising N234 carbon black
and
having MW, greater than 0.35 x 106 have excellent macro-dispersion, such as
D(%)
not more than 03% or even 0.2%. Compound properties and performance
characteristics for invention sample No. 14 and various control samples shown
in Fig.
18, comprising N234 carbon black, are set forth in Table 31 below. It can be
seen
that invention sample No. 14 has good resistance to crack growth, as indicated
by its
crack growth rate value of only 2.08 cm/million cycles.
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Table 31 Compound Properties of NR Compounds
Containing N234 Carbon Black at 55 phr Loading
Sample No. Mooney Hardness E100 E300 Tensile EJ
ML(1+44100=C (psi) Ipsi) (Fssi) (%)
control273 94.5 68.0 386 2077 3718 511
control 274 121.6 69.6 464 2299 3925 501
conuol275 121.4 72.5 564 2545 3994 472
control 276 132.2 71.9 511 2259 3964 520
cor,trol277 79.6 68.5 468 2453 3857 469
confrol278 96.3 70.0 531 2499 3874 469
control279 108.6 69.0 406 2131 3863 532
contro1280 120.3 71.5 476 2273 3852 502
control 281 76.4 69.7 556 2723 4027 451
conuol282 89.8 69.8 553 2574 3896 465
control 283 93.6 69.6 506 2416 3867 475
control 284 106.7 71.8 526 2384 3788 484
control285 73.3 69.3 529 2586 3831 444
control 286 79.2 69.5 531 2574 3856 456
control 287 77.8 70.7 544 2486 3834 461
controi 288 82.8 71.2 485 2295 3799 499
invention 14 82.6 71.5 500 2440 3883 531
Sample No. Rebound Crack Growth Rate Abnsion loss Tan 6 Tan S
(cm/mililon cycles) (g) @ 0'C @ 60'C
control 273 45.9 214 0.0563 0.285 0.183
contrtrol274 47.2 1.84 0.0583 0.274 0.173
control 275 46.1 1.70 0.0538 0.284 0.172
contral276 46.9 1.21 0.0620 0.270 0.173
control 277 47.1 2.22 0.0628 0.305 0.173
contrul278 45.8 2.40 0.0634 0.299 0.196
control 279 45.4 2.00 0.0680 0.306 0.198
contro1280 44.2 1.81 0.0646 0.29B 0.198
control281 46.3 3.10 0.0598 0293 0.174
contro1282 46.5 2.33 0.0537 0.307 0.182
control 283 46.4 2.41 0.0594 0.309 0.186
control 284 44.2 1.99 0.0579 0.304 0.190
control 285 47.0 2.99 0.0554 0.295 0.178
conirol286 45.6 2.85 0.0551 0294 0.172
control 287 45.4 2.93 0.0569 0.305 0.187
control 288 44.0 2.39 0.0647 0.316 0.198
invention 14 45.1 2.08 0.0698 0.310 0.198
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Fig. 19 shows the dispersion quality and MW., of the invention and control
samples described above comprising N110 carbon black at 55 phr loading. The
data
shown in Fig. 19 clearly reveals that the macro-dispersion quality of the
novel
elastomer composites of the invention comprising N110 carbon black, over a
wide
range of MW.01 values, is significantly superior to that of the control
samples. The
macro-dispersion values for the elastomer composites of the invention
comprising
NI 10 carbon black, as shown in Fig. 19, are described by the following
equations:
D(%) < 0.5% (19)
when MW., < 0.35 x 106; and
log (D) < log (0.5) + 2.5 x[MW~, -(0.6 x 106)] x 10-6 (20)
when 035 x 106 < IVIWSo, < 1.1 x 106.
None of the control samples achieved macro-dispersion quaIity of 0. 5% at any
MW.,,
even after dry mixing sufficiently to degrade MW., below 0.35 x 106- In
contrast,
elastomer composites of the invention comprising N 110 carbon black and having
MWfa, above 0.35 x 106 have excellent macro-dispersion, such as D(%) less than
0.2%.
Fie. 20 shows the dispersion quality and MW., of invention sample 22 and
the control samples described above comprising N351 carbon black at 33 phr
loading.
The data shown in Fig. 20 clearly reveals that the macro-dispersion quality of
the
novel elastomer composites of the invention comprising N351 carbon black, over
a
wide range of MW~~ values, is significantly superior to that of the control
samples.
The macro-dispersion values for the elastomer composites of the invention
comprising N351 carbon black, as shown in Fig. 20, are described by the
following
equations:
D(%) < 0.3% (21)
when MW,,, < 0.55 x 106; and
log (D) < log (0.3) + 2.0 x[MW., - (0.55 x 106)] x 10-1 (22)
when 0.55 x 106 < MW,,< < 1.1 x 106.
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None of the control samples achieved macro-dispersion quality of 1.0% at any
MW.,,
even after dry mixing sufficiently to degrade MW,o, below 0.35 x 106. In
contrast,
elastomer composites of the invention comprising N351 carbon black and having
MW,o, above 0.35 x 106 have excellent macro-dispersion, such as D(%) less than
0.2%.
Fig. 21 shows the dispersion quality and MW., of the invention sample No.
23 and control samples described above comprising STERLING 6740 carbon black
at 55 phr loading. The data shown in Fig. 21 clearly reveals that the macro-
dispersion quality of the novel elastomer composites of the invention
comprising
STERLINGO 6740 carbon black, over a wide range of MW., values, is
significantly
superior to that of the control samples. The macro-dispersion values for the
elastomer composites of the invention comprising STERLING 6740 carbon black,
as shown in Fig. 21 are described by the following equations:
D(%) < 0.1 % (23 )
when MW,,, < 0.3 x 106 ; and
log (D) < log (0.1) + 2.0 x[MW,,, -(0.3 x 106)] x 101 (24)
when 0.3 x 106 < MW., < 1.1 x 106.
None of the control samples achieved macro-dispersion quality of 0.1 % or even
0.2% at any MW.,, even after dry mixine sufficiently to degrade MW., below 0.3
x 106. In contrast, elastomer composites of the invention comprising STERLING
6740 carbon black and having MW.,, above 0.3 x 106 have excellent macro-
dispersion, such as D(%) less than 0.2% and even less than 0.1 %. Compound
properties and performance characteristics for invention sample No. 23 and the
control samples shown in Fig. 21, comprising STERLING 6740 carbon black,
are set forth in Table 32 below. It can be seen that invention sample No. 23
has
good resistance to crack growth, as indicated by its crack growth rate value
of
only 0.91 cm/million cycles. In fact. tce invention sample is far superior to
the
corresponding control samples. This is believed to be due largely to the
better
IvNV,., and macro-dispersion of carbon black in the invention sample, as
discu'ssed
above.
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Table 32 Compound Properties of NR Compounds
Containing STERLING 6740 Carbon Black at 55 phr Loading
Sampie No. Mooney Hardness Et00 E300 Tensile E3
ML(1+4)@100=C (pSi) (psi) (psi) (%)
control412 75.50 65.1 467.0 2308.0 3519 451
control 413 85.70 65.7 469.0 2314.0 3655 479
control 414 92.70 67.7 462.0 2243.0 3613 472
control 415 99.60 66.9 492.0 2260.0 3572 477
control 416 74.50 65.8 521.0 2468.0 3584 445
control 417 78.20 67.1 502.0 2372.0 3445 436
control 418 82.00 66.0 534.0 2418.0 3604 453
control 419 86.10 67.8 540.0 2330.0 3620 475
control 420 66.70 66.0 515.0 2382.0 3468 444
control 421 76.30 67.8 488.0 2310.0 3375 440
contro1422 78.30 65.8 548.6 2440.0 3549 442
~:. control 423 82.10 66.5 487.0 2219.0 3452 466
control 424 64.80 66.5 541.0 2448.0 3397 425
control 425 67.50 66.5 524.0 2374.0 3474 445
contro1426 70.30 66.9 546.0 2351.0 3428 446
control 427 71.00 68.1 554.0 2340.0 3322 435
inveniion 23 110.50 64.8 453.6 2241.0 3324 443
Sample No. Rebound Crack Growth Rate Abrasion loss Tan 6 Tan 6
(cmimillion cycles) (g) @ 0=C @ 60=C
control 412 59.8 5.04 0.127 0.202 0.107
control 413 60.0 3.63 0.128 0.203 0.108
control414 59.3 3.96 0.126 0.208 0.114
contrvl415 58.8 4.56 0.12 0.217 0.118
control 416 60.3 5.67 0.117 0.188 0.094
control 417 60.0 4.67 0.112 0.202 0.104
control 418 59.3 4.23 0.125 0.204 0.105
control419 57.5 3.22 0.122 0.218 0.117
contro1420 60.0 4.23 0.131 0.204 0.099
control 421 58.8 3.84 0.127 0.206 0.105
conuol422 59.8 3.98 0.126 0.210 0.106
control 423 56.8 3.85 0.12 0.213 0.117
control 424 58.3 4.54 0.131 0.200 0104
control 425 58.8 3.65 0.129 0.207 0.100
control 426 58.0 3.07 0.134 0.211 0.110
control 427 56.9 3.25 0.126 0.217 0.115
invention 23 57.3 0.91 0.1642 0.204 0.124
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Addition Examples: Cured Samples
A number of the masterbatch samples described above, including both
selected invention samples and corresponding control samples, were cured and
tested.
Specifically, samples were mixed accordingly to Stage II in Table 8, above,
using the
formulation of Table 9, to produce a final compound. The final compound in
each
case was then cured in a mold using standard techniques at about 150 C until
substantially complete cure was achieved. Performance characteristics of the
cured
samples were determined by measuring their respective crack growth rates in
accordance with the measurement technique set forth above, i.e., using a
rotating
flexing machine per ASTM D3629-94. The rotating type flexing machine used to
measure crack growth is commercially available and well known. It is
discussed, for
example, in the Proceedings of the International Rubber Conference, 1995
(Kobe,
Japan), Paper No. 27A - 6 (p. 472 - 475). The compounds were tested at 100 C
and
at a 45 flexing angle. It is generally accepted by those skilled in the art
that crack
growth rate in such compounds is affected by the molecular weight of the
natural
rubber and the dispersion quality of the carbon black i.e., by the MW.i and
D(%)
values of the compounds. I-i~igher MW,, and lower D(%) correlate well with
reduced
crack growth rate. The crack growth rate and other information for invention
samples nos. 9, 10 and 16 are set forth in Table 33 below. The corresponding
test
results for corresponding control samples is set forth in Table 34 below,
grouped by
choice of carbon black. Also, Tan 8. @ 60 C was measured for invention samples
nos. 24 - 32 and for corresponding control samples. The Tan 5. @ 60 C values
for
the invention samples are set forth in Table 35 below. The corresponding test
results
for control samples is set forth in Table 36 below.
Control samples No. 444 - 450 shown in Table 36 were made in accordance
with the procedures described above for control sample code M2D 1 using RSS I
natural rubber. All used carbon black N234 at the loading level (phr) shown in
Table
36, along with 5 phr extender oil.
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Table 33 Crack Growth Rate of Invention Sampfes
lnvention Sample No. ~ CB/Loading/Oll Mw,,, (K) CGR (cmimillion cycles)
9 N32615510 666 0.77
R660/5510 678 0.69
16 N234/5510 500 0.88
Table 34 Crack Growth Rate of Control Samples
N234155phr/0 N326155phr/0
RSS1 RSS1
Code Samp/e Mw.,, CGR Code Sample Mw,, CGR
No. (K) (cm/million cycles) No. (K) (cm/million cycles)
M1D1 273 585 2.14 M1D1 145 550 2.84
MID2 274 669 1.84 MID2 146 636 2.52
MID3 275 759 1.70 M103 147 650 2.03
MID4 276 896 1.21 MID4 148 724 1.63
M2D1 277 580 2.22 M201 149 517 3.39
M2D2 278 602 2.40 M2D2 150 Si2 2.1-7
M2D3 279 631 2.00 M2D3 151 613 2.61
M2D4 280 667 1.81 M2D4 152 696 2.79
M3D1 281 457 3.10 M3DI 153 489 3.12
M3D2 282 476 2.33 M302 154 521 3.35
M3D3 283 493 2.41 M3D3 155 504 3.63
M3D4 384 495 1.99 M3D4 156 538 3.55
M4D1 285 372 2.99 M4DI 157 415 3.02
M4D2 286 382 2.85 M4D2 158 447 3.81
M4D3 287 381 2.93 M4D3 159 466 3.23
M4D4 288 403 2.39 M4D4 160 469 3.19
Regal 660/55phr/0 Regal 660/55phr/0
RSS1 RSS1
Code Sample Mw,,, CGR Code Sample Mwf,, CGR
No. (K) (cm/million cycles) No. (K) (cm/million cycles)
M1D1 177 674 M3DI 185 473 4.59
M1D2 178 792 2.34 M3D2 186 506 4.06
MID3 179 891 2.78 M3D3 187 562 3.53
MID4 180 676 2.98 M3D4 188 559 3.79
M2D1 181 598 3.41 M4DI 189 401 3.71
M2D2 182 602 3.11 M4D2 190 426 4.14
M2D3 183 697 3.15 M4D3 191 466
M2D4 184 659 3.11 M4D4 192 449 4.78
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Table 35 Tan S at 60=C for Invention Samples
Invention Sample No. N234 Loading/Oll (phr) Mw,, (K) Max.Tan 8@ 60'C
24 48/5 569 0.169
25 53/5 485 0.176
26 5815 447 0.191
27 63/5 403 0.219
28 68/5 378 0.227
29 49/5 618 0.159
30 54l5 482 0.171
31 63/5 390 0.228
32 6515 325 0.224
Table 36 Tan 5 at 60=C for Control Samples
Sample No. MW D N234 Loading/Oil Max.Tan D
(KI ('~) (phr) (@60 C)
444 428 0.25 37/5 0.154
445 409 0.37 42/5 0.170
446 379 0.42 46/5 0.179
447 361 0.58 51/5 0.195
448 366 0.27 53/5 0.212
449 290 0.39 5815 0.215
450 296 0.64 63/5 0.245
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It can be seen from a comparison of Table 33 and 34 that advantageously lower
crack
growth rate is achieved by the invention samples, compared to the control
samples.
Lower crack growth rate correlates with good durability and related
characteristics
for numerous applications, including tire applications and the like. In
addition, it can
be seen from a comparison of Tables 35 and 36 that better Tan 5. values are
achieved by the invention samples, that is, values which are lower than the
values of
the control sample. Accordingly, improved performance is achieved by the
invention
samples for numerous product applications including, for example, tire
applications
and the like requiring low hysteresis for correspondingly low rolling
resistance.
The advantageous performance characteristics of the elastomer composites
of the invention are exemplified by the crack growth rate of invention sample
no. 16
comprising N234 carbon black and corresponding test results for control
samples
nos. 273 to 288 shown graphically in Fig. 22. Specifically, Fig. 22 clearly
demonstrates a correlation between MW,,,, and crack growth rate for the
control
samples, as well as the advantageous impact of excellent macro-dispersion in
the
elastomer composites of the present invention. It should be understood that
the
MW, , values shown in Figs. 22 - 24 and in Tables 33 - 36 are for the
masterbatch
materials prior to cure. The molecular weight of the cured material is
understood to
correlate well to the MW,o, value of the uncured masterbatch. The crack growth
rate
of the control samples over an MW., range of about .25 x 106 to .6 x 106 is
seen to
fit well along a straight line correlation to MW, In contrast, the invention
sample
no. 16 at MWm, 0.5 x 106 has significantly better (i.e., lower) crack growth
rate than
any of the corresponding control samples, due to the better macro-dispersion
D(%)
of the invention sample. This is further established by the similar showing in
Fig. 23,
wherein the crack growth rate of invention sample no. 9 comprising N326 carbon
black is seen to be significantly lower than that of any of the corresponding
control
samples nos. 145 to 160, and is well below the correlation line. Likewise in
Fig. 24
the excellent macro-dispersion of invention sample no. 10 is seen to result
again in
a crack growth value wluch lies far below the correlation line between crack
growth
rate and MW,., established by the corresponding control samples nos. 177 to
192.
In Fig. 25, the max tan 6 at 60 C is shown graphically to be better, i.e.,
lower, for
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invention samples nos. 24 to 28 and invention samples nos. 29 to 32 than for
corresponding control samples nos. 444 to 450.
The superior crack growth results discussed above for elastomer composites
of the present invention not only demonstrates advantageous fatigue
properties, but
also indicates advantageous fracture properties, such as excellent tear and
cut-and-
chip resistance. The superior hysteresis results discussed above for the
elastomer
composites of this invention not only demonstrate advantageously low rolling
resistance (and correspondingly higher fuel economy) for motor vehicle tire
applications, but also indicates advantageous improvement in related
performance
properties, such as reduced heat build-up. One or more of these superior
properties,
fatigue and fracture resistance, low hysteresis, low heat build-up, etc.,
render
elastomer composites of the present invention well suited for use in
commercial
applications such as tire applications and in industrial rubber products.
Regarding tire
applications, various preferred embodiments of the invention are particularly
well-
suited for use as: tire tread, especially in tread for radial and bias truck
tires, off-the-
road ("OTR") tires, airplane tires and the like; sub-tread; wire skim;
sidewalls;
cushion gum for retread tires; and similar tire applications. The superior
performance
characteristics achieve by various preferred embodiments of the invention can
provide
improved tire durability, tread life and casing life, better fuel economy for
the motor
vehicle and other advantages. Regarding industrial rubber products, various
preferred embodiments of the invention are particularly well-suited for use
as: engine
mounts, hvdro-mounts, bridge bearings and seismic isolators, tank tracks or
tread,
mining belts and similar products applications. The superior performance
characteristics achieved by various preferred embodiments of the invention can
provide improved fatigue life, durability and other advantages for such
product
applications.
Figs. 26 - 29 are graphical representations of carbon black morphology,
structure (DBPA) and surface area (CTAB), corresponding generally to Fig. 8.
Carbon black morphology region 261 in Fig. 26 includes carbon blacks currenlly
in
commercial use for OTR tire tread applications. Arrow 262 indicates the
direction
in which region 261 can be advantageously extended in accordance with the
present
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invention. Petformance characteristics such as cut-and-chip resistance, crack
growth
resistance and tear resistance are understood to improve generally in the
direction of
trend arrow 262 subject, however, in the past, to offsetting degradation of
these and
other characteristics due to reduced molecular weight of the natural rubber
and/or
poorer macro-dispersion resulting from the use of such higher surface area,
lower
structure carbon blacks. Elastomer composites of the present invention can
employ
such lower structure, higher surface area carbon black indicated by trend
arrow 262
to achieve significantly improved OTR trend materials, in view of their
excellent
macro-dispersion and MW,o,.
Similarly, carbon black morphology region 271 in Fig. 27 includes carbon
blacks currently in commercial use for truck and bus (T/B) tire tread
applications.
Arrow 272 indicates the direction in which region 271 can be advantageously
extended in accordance with the present invention. Performance
characteristics, such
as wear resistance, are understood to improve generally in the direction of
trend
arrow 272 subject, however, in the past, to offsetting degradation of these
and other
characteristics due to reduced molecular weight of the rubber and/or poorer
macro-
dispersion resulting from use of such higher surface area carbon blacks.
Elastomer
composites of the present invention can employ such higher surface area carbon
blacks indicated by trend arrow 272 to achieve improved TB tread materials, in
view
of their excellent macro-dispersion and MW.,.
Similarly, carbon black morphology regions 281 and 283 in Fig. 28 show
carbon blacks currently in commercial use for tread base and passenger car
(PC) tire
tread, respectively. Trend arrows 282 and 284 indicate the direction in wluch
region
281 and 283, respectively, can be advantageously extended in accordance with
the
present invention. Performance characteristics such as heat build-up (HBU) and
rolling resistance are understood to improve for tread base in the direction
of trend
arrow 282 subject, however, in the past, to offsetting degradation of these
and other
characteristics due to reduced molecular weight of the rubber and/or poorer
macro-
dispersion resulting from use of such higher surface area, lower structure
carbon
blacks. Likewise, performance characteristics such as rolling resistance are
understood to improve for PC tread in the direction of trend arrow 284
subject,
CA 02511365 1997-03-25
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however, in the past, to offsetting degradation of these and other
characteristics due
to reduced molecular weight of the rubber and/or poorer macro-dispersion
resulting
from use of such higher surface area, lower structure carbon blacks. Elastomer
composites of the present invention can employ higher surface area, lower
structure
carbon blacks indicated by arrows 282 and 284 to achieve improved tread base
and
PC tread, respectively, in view of the excellent macro-dispersion and the
optional
preservation of high molecular weight in such elastomer composites.
Similarly, carbon black morphology regions 291, 293 and 294 in Fig. 29 show
carbon blacks currently in commercial use for sidewall, apex and steel belt
tire
applications, respectively. Trend arrows 292 and 295 indicate the direction in
which
re2ion 291 and 294, respectively, can be advantageously extended in accordance
with
the present invention. Performance characteristics such as heat build-up (HBU)
and
fatigue life are understood to improve for sidewall in the direction of trend
arrow 292
subject, however, in the past, the offsetting degradation of these and other
characteristics due to reduced molecular weight of the rubber and/or poorer
macro-
dispersion resulting from use of such lower structure carbon blacks. Likewise,
performance characteristics such as heat buildup, processing and wire adhesion
are
understood to improve for steel belt elastomeric materials in the direction of
trend
arrow 295 subject, however, in the past, to offsetting degradation of these
and other
characteristics due to reduced molecular weight of the rubber and/or poorer
macro-
dispersion resulting from use of such higher surface area, lower structure
carbon
blacks. Elastomer composites of the present invention can employ hieher
surface
area and/or lower structure carbon blacks as indicated by arrows 292 and 295
to
achieve improved sidewall and steel belt rubber materials, respectively, in
view of the
excellent macro-dispersion and the optional preservation of high molecular
weight
in such elastomer composites.
Additional Examples: Preferred Embodiment and Control Samples
Comprising Other Fillers
Additional samples of elastomer composites in accordance with certain
preferred embodiments of the present invention, and corresponding control
samples,
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were prepared. A first group of these employed a multiphase aggregate filler
of the
type referred to above as a silicon-treated carbon black.
Specifically, invention samples nos. 33 - 34 employed ECOBLACK silicon-
treated carbon black commercially available from Cabot Corporation (Billerica,
Massachusetts). Such ECOBLACK filler has morphological properties, i.e.,
structure and surface area, similar to that of carbon black N234. Sample no.
33
employed 45 phr ECOBLACK filler and no extender oil. Sample no. 34 employed
68 phr ECOBLACK filler and no extender oil. Typical filler and extender oil
usage
for various product applications are shown in Table 37, for elastomer
composites of
the invention comprising natural rubber and a blend of carbon black and silica
filler.
It should be understood that the use of silica filler in the compositions
shown in Table
37 would typically replace a like amount of the carbon black filler.
97
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PCT/US97/05276
t4 '
O
'J r N N
~ r r r
{O p
y
~ = t
J N ~ ~ N ~ e~7 M ~7
~ 0 r r r r r
O
IC. b O ~ tO O
t7 iO ^ r
= ~ .~ t Z ... ~ ..
G
V t00 ~ ~ ~ ~ ~ ~p
O
~ r r r r r r ~
m r
b 'O !~9 1C)0 'r
0
.G
~
C)
of ~
Ch 1o
N
Z =
m N A
t~
z b b Z
~ Y N Ilf~f Z = ~Z Z
` b
Q M N ~ Z t' f Z Z z l' 1
r r ~ N
z z
~ a Z a o C-4 ~ ~ Z
~ =- =- Z Z Z
~
Z Z
~
o z
tA
O Z
~ z
U. W
lr m Q
Z ~ ~ w Q + O
c.~ 7 F= ~ F~- ~ m d
a m 7 ` v Q a.
M a O V N J
~ F
~
98
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A second group of samples employed a blend or mixture of silica and carbon
black. In embodiments of the present invention employing a blend of carbon
black
and silica fillers, it is generally preferred that they be used in weight
ratio of at least
about 60:40. That is, the carbon black preferably comprises at least about 60
weight
percent of the filler to achieve good coagulation of the elastomer and to
reduce or
eliminate reagglomeration of the silica in the masterbatch. In particular, in
examples
nos. 3 5 - 3 8, as shown in Table 40, carbon black is used together with
particulate
SiOZ filler HiSil 233 available from PPG Industries (Pittsburgh,
Pennsylvania,
USA), having surface area BET of 150 m2/g, surface area DBPA of 190 mils/100g,
pH of 7 and a primary particulate size of 19 nanometers.
All of the invention samples, i.e., additional invention samples nos. 33 - 38,
were prepared in accordance with the procedures and apparatus used for
invention
samples 1- 32, as described above. Process and apparatus details for each of
invention samples nos. 33 - 38 is given in Table 38, below. The field latex or
concentrate employed in samples nos. 33 - 38, as the case may be, is the same
as
described above with reference to Table 24. It will be appreciated that the
data in
Table 38 parallels that provided in Table 25, above, for invention samples
nos. 1-32.
The carbon black filler "CRX2000" listed in Table 38 is the ECOBLACK silicon-
treated carbon black described above.
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CA 02511365 1997-03-25
WO 97/36724 PCT/US97/05276
m
~ y O
p p~~
0000~ ~NN
0 0
RJ NNNN H mMVOtpf~pD
M P''/ m aaO O LL7 0
Q ~~ o = a M f~ f7 C7 P7 M
~-~,-.-~c' '
o ~ O
0
~ tA 1[~ tA t0 10 1A tA IA 0 tC.l Ip Il~ m ~1 ~1 =- N Qf N V+m+ ZCD N c O) C
Q)
D~,,OO0000 `000000 aQ~m^ O~M~ ~~OOOMe~7ef
m a
Z
p~ Ol U U U U V U
N N N N N N . L ` M c'7 ~'7 M M M m m sf m 07 M r N a O O O O O O
~ yQ`OOOOOO OlNNNNNN I- LnVQ QN ~~-9 A-9
= ~~ ~` F F F- F F-
. . ' V
y Co Go m C! m G7
a00KJ000 M¾'~ c"lc'~M M = ~~~~ O~_ ;000000
p` p O O O O O O a V O` N
Va
p 10 ~
3 -= z `0 -.
o N ~
,oooooV ~tqcccotDCOto `Qvcvcc
~ y~a' ~ NN =r-.-.-.-~r- p~~-.0000000 p~~Q t~QaTQ
4 = y ~ m C W~i` a v
E y O R3
n N k t/!
N p p 1.4 s
Q =
o
~ `r~r~tititi-~--~Q ~o o c~
C O MOmMO ~`NNNNNN aM C~ MC7lJM L p (p O N
t Q tl] Q M N V 6~
000 000 - n e- n Q
>U~ `000000 fQ
ao
W ac vc ~ic~rcic-~Z oooooo m mooocooo~ ~+nornctirn~
~ :k% XXZZZ.~ Ciririmrimm yi i M
~i~v~i
~
U U W
y p
m
ax x x x x
C7 CT m y OJ = y
" N N t0 l0 l0 U ~. O O O O C)
O O E N N N O O 7 Z p N O O O O
x- C r- ~- .-- H ~ , U'i O m O
m'O 10 O O O O O O 0 0 Lti 0 C tA c07 N N
~ d N a7 d d '~
J ~ 4
io ~~jy y ~
oZ~ oi oz oi
'v m M Q 1- N oM Q it~CO1~OD mM'3V~ a M c'') ~ C) M 0 M M ZQ,M l*7 ~+) c~I M M
a C t~ 7 P~7 C~^J c' 7
^7 f`~ t a l" M7 ~ f'~7 f' ~ ') c t~
a~l a~ aE a~ '
~H) ~y1 ~t~i ~ ~v)
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The control samples 451-498 were prepared in accordance with the
procedures and apparatus described above for control samples nos. 1-450. The
processing code (see Table 13 above), filler loading, rubber, MW., and macro-
dispersion for masterbatches 451-466 are set forth below in Table 39. The
processing code, filler loading, rubber, MW.1 and macro-dispersion values of
the
invention samples nos. 33-38 (along with the filler and oil loadings for
convenient
reference) are shown in Table 40. It will be seen from Table 39 that control
samples
451-466 correspond in composition to invention samples nos. 33 and 34.
Similarly,
control samples nos. 467-498 correspond to invention samples nos. 35-38.
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Table 39
CRX 2000/44/0 CRX 200015810
RSS1 ( RSSI
Code Sampfe Mw., D('/.) Samp/e Mw,,, D(Y.)
No. (K) No. (K)
M2 909 909
M3 590 590
M2D1 451 461 3.48 459 333 8.61
M2D2 452 474 3.68 460 392 5.71
M2D3 453 489 7.17 461 388 9.48
M2D4 454 515 6.28 462 394 8.05
M3D1 455 393 2.89 463 280 2.23
M3D2 456 422 287 464 298 2.13
M3D3 457 435 4.15 465 350 4.05
M3D4 458 449 323 466 379 7.22
Table 40 Sal Molecular Weight and Undispersed Area of Invention Samples
/nverrtion Sample No. CB/Loaaing/Oll Mw.,, (K) D
33 CRX 200014410 380 0.18
34 CRX 2000/5810 448 0.10
35 N220M1EsiI233/43/10/5 500 0.14
36 N234/1-111sif 233/40110/0 490 0.36
37 N234/HilsiI233/3020/0 399 0.23
38 STERUNG 6740/Hilsii 233/30/20/0 354 0.39
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Table 41
N220/Hilsil233/43/1015 N234/Hiisil233/40/10/0
RSS1 RSS1
Code Sample Mw,,, D('/.) Sample Mw,,, D(`~)
No. (K) No. (K)
M2 803 909
M3 601 590
M2D1 467 493 1.51 475 443 8.74
M2D2 468 537 2.61 476 517 10.9
M2133 469 523 2.82 477 569 12.5
M2D4 470 615 2.95 478 592 8.25
M3D1 471 417 0.95 479 358 6.65
M3D2 472 438 1.40 480 420 13.8
M303 473 433 2.15 481 516 13.9
M3D4 474 485 2.22 482 447 7.25
N234/HHsi1233130/20/0 1 STERLING 6740/Hllsil 233I3012010
RSS1 RSS1
Code Sample
Mw,,,, D(`!) Sample Mw,a D
No. (K) No. (K)
M2 909 909
M3 590 590
M2D1 483 394 4.37 491 430 3.77
M2D2 484 507 5.66 492 488 4.39
M2D3 485 526 4.7 493 517 5.37
M204 486 568 5.94 494 563 4.66
M301 487 377 8.39 495 375 3.5
M3D2 488 363 4.49 496 380 2.73
M3D3 489 376 5.07 497 419 2.72
M3D4 490 432 5.26 498 448 3.29
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The excellent carbon black dispersion in the masterbatches of invention
samples 33-38 is demonstrated by comparison of the macro-dispersion quality
and
MW,,, values shown in Tables 39-41. The invention samples nos. 33-34 made with
ECOBLACK silicon-treated carbon black, and the corresponding control samples
are compared in the semi-log plot of Fig. 30. Excellent carbon black
dispersion is
seen in Fig. 30 for the invention samples, representing preferred embodiments
of
elastomer composites in accordance with the present disclosure. The invention
samples advantageously are below line 301 in Fig. 30, whereas all of the
control
samples have poorer dispersion, being above line 301. In fact, the preferred
embodiments shown in Fig. 30 fall below a D(%) value of .2% even at an MW,o,
value advantageously exceeding .4 x 106. The data shown in Fig. 30 clearly
reveals
that the macro-dispersion quality of the novel elastomer composites, disclosed
here,
comprising silicon-treated carbon black is sisnificantly superior to that
achievable
using comparable ingredients in prior dry mixing methods. The macro-dispersion
values for the elastomer composites of the invention shown in Fig. 30 are
described
by the following equations:
D(%) < 1.0% (25)
when MW,, is less than 0.4 x 106; and
log (D) < log (1.0) + 2.0 x[MV~',o, -(0.4 x 106)] x 10-6 (26)
when 0.4 x 106 < MW,,, < 1.1 x 106
It will be recosnized that D(%) is the percent undispersed area measured for
defects
greater than 10 microns and 1% is the threshold macro-dispersion quality for
the
masterbatches in accordance with these preferred embodiments of the present
...:.,
invention. That is, none of the dry masticated masterbatches achieved macro-
dispersion quality of 1.0% or better at any MW.,, even after dry mixing
sufficiently
to degrade MW., below .4 x 106. The preferred embodiments shown in Fig. 30
fall
well below the threshold. It can be seen that the elastomer composites of the
invention comprising silicon-treated carbon black provide heretofore
unachieved
balance between macro-dispersion quality and MW+o,.
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Invention samples nos. 35-38 comprising carbon black blended with silica
filler and corresponding control samples are compared in the semi-log plot of
Fig. 31.
Specifically, Fig. 31 shows the macro-dispersion values and IvIWj values of
the
invention samples nos. 35 - 38 and corresponding control samples nos. 467 -
498.
Excellent carbon black dispersion is seen in Fig. 31 for the invention
samples,
representing preferred embodiment of elastomer composites in accordance with
the
present disclosure. The invention samples advantageously are below line 3 11
in Fig.
31, whereas all of the control samples have poorer dispersion, being above
line 311.
In fact, all of the preferred embodiments shown in Fig. 31 fall below a D(%)
value
of.4%. The data shown in Fig. 31 clearly reveals that the macro-dispersion
quality
of the novel elastomer composites, disclosed here, comprising carbon
black/silica
blends over a range of MW, values, is significantly superior to that
achievable using
comparable ingredients in prior dry mastication mixing methods. The macro-
dispersion values for the elastomer composites of the invention shown in Fig.
31 are
described by the following equations:
D(%) < 0.8% (27)
when VIW.i is less than 0.5 x 106; and
log (D) < 1og (0.8) + 2.2 x[MW., -(0.5 x 106)) x 10-6 (28)
when 0.5 x 106 < MW., < 1. I x 106
It will be recognized that D(%) is the percent undispersed area measured for
defects
greater than 10 microns and .8% is the threshold macro-dispersion quality for
masterbatches in accordance with these preferred embodiments of the present
invention. That is, none of the dry masticated masterbatches achieved macro-
dispersion quality of 0.8% or better at any MW,,,, even after dry mixing
sufficiently
to degrade MW,, below .4 x 106. The preferred embodiments shown in Fig. 31
fall
well below the threshold macro-dispersion value of.8 /a, and even below .4%.
It can
be seen that the elastomer composites of the invention comprising carbon
black/silica
blend filler provide heretofore unachieved balance between macro-dispersion
auality
and MW~i.
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In view of the foregoing disclosure, it will be apparent to those skilled in
the
art that various additions, modifications, etc. can be made without departing
from the
true scope and spirit of the invention. A!I such additions and modifications
are
intended to be covered by the following claims.
106
