Note: Descriptions are shown in the official language in which they were submitted.
CA 02412709 2002-11-25
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Filled Elastomeric Butyl Compounds with improved scorch
safet
Field of the Invention
s The present invention relates to halogenated butyl elastomers with
improved scorch safety, in particular bromobutyl elastomers with improved
scorch safety.
Background of the invention:
to It is known that reinforcing fillers such as carbon black and silica
greatly improve the strength and fatigue properties of elastomeric compounds.
It is also known that chemical interaction occurs between the elastomer and
the filler. For example, good interaction between carbon black and highly
unsaturated elastomers such as polybutadiene (BR) and styrene butadiene
is copolymers (SBR) occurs because of the large number of carbon-carbon
double bonds present in these copolymers. Butyl elastomers may have only
one tenth, or fewer, of the carbon-carbon double bonds found in BR or SBR,
and compounds made from butyl elastomers are known to interact poorly with
carbon black. For example, a compound prepared by mixing carbon black
Zo with a combination of BR and butyl elastomers results in domains of BR,
which contain most of the carbon black, and butyl domains which contain very
little carbon black. It is also known that butyl compounds have poor abrasion
resistance.
Canadian Patent Application 2;293;149 shoves that it is possible to
2s produce filled butyl elastomer compositions with much improved properties
by
combining halobutyl elastomers with silica and specific silanes. These silanes
act as dispersing and bonding agents - between the halogenated butyl
elastomer and the filler. However, one disadvantage of the use of silanes is
the evolution of alcohol during the process of manufacture and potentially
3o during the use of the manufactured article produced by this process.
Additionally, silanes significantly increase the cost of the resulting
manufactured article.
I
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Co-pending application CA 2;339,080 discloses a process for preparing
compositions containing halobutyl elastomers and organic compounds
containing at least one basic nitrogen-containing group and at least one
hydroxyl group in which there is enhanced interaction 'between the elastomer
s and a filler, especially a mineral filler. Of particular interest were
compounds
containing primary amine and hydroxyl groups such as ethanolamine. While
solving the problem of enhancing the interaction between elastomer and filler,
said compositions have to be processed carefully to prevent any undesirable
scorch of the composition. The skilled in the art understands the' term scorch
to as premature crosslinking of the composition during processing.
Summary of the Invention:
The present invention provides a process for preparing compositions
containing halobutyl elastomers, organic compounds containing at feast one
is basic nitrogen-containing group and at least one hydroxyl group, and
hydrated
metal halogenides. In this process there is enhanced interaction between the
elastomer and a filler, especially a mineral filler with improved scorch
safety.
The invention also provides filled halobutyl elastomer compositions containing
halobutyl elastomers, organic compounds containing at least one basic
2o nitrogen-containing group and at least one hydroxyl group, and ane or more
hydrated metal halogenides. Those compositions have improved properties
when compared to known carbon black-filled halobutyl ' elastomeric
compositions combined with an enhanced scorch safety. In particular it
provides a means to produce such filled compositions without the evolution of
2s alcohol.
Of particular interest are organic compounds containing at least one
basic nitrogen-containing group and at least one hydroxyl group containing
primary amine and hydroxyl groups such as ethanolamine. These organic
compounds are believed to disperse and bond the silica to the halogenated
3o elastomers.
Accordingly, in a further aspect the present invention provides a
process which comprises mixing a halobutyl elastomer with a filler, especially
a mineral filler, in the presence of an additive which is an organic compound
a
CA 02412709 2002-11-25
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which has at least one hydroxyl group and at least one basic nitrogen-
containing group and one or more hydrated metal halogenides, and curing the
resulting filled halobutyl elastomer. The resulting composition, having
improved scorch safety, forms another aspect of the invention.
s The halobutyl elastomer that is admixed with the filler and one or more
organic compounds which have-at least one hydroxyl group and at least one
basic nitrogen-containing group and one or more hydrated metal halogenides
may be a mixture with another elastomer or elastomeric compound. The
halobutyl elastomer should constitute more than 5% of any such mixture.
to Preferably the halobutyl elastomer should constitute at least 10% of any
such
mixture. In some cases it is preferred not to use mixtures but to use the
halobutyl elastomer as the sole elastomer. If mixtures are to be used,
however, then the other elastomer may be, for example, natural rubber,
polybutadiene, styrene-butadiene or poly-chloroprene or an elastomer
is compound containing one or more of these elastomers.
The filled halobutyl elastomer can be cured to obtain a product, which
has improved properties, for instance in abrasion resistance, rolling
resistance
and traction. Curing can be effected with sulfur. The preferred amount of
sulfur is form 0.3 to 2.0 parts by weight per hundred parts of rubber. An
2o activator, for example zinc oxide, may also be used, in an amount of from 5
parts to 2 parts by weight. Other ingredients, for instance stearic acid,
antioxidants, or accelerators may also be added to the elastomer prior to
curing. Sulphur curing is then effected in known manner. See, for instance,
chapter 2, "The Compounding and Vulcanization of Rubber", of "Rubber
2s Technology", 3'~ edition, published by Chapman & Hail, 1995, the disclosure
of which is incorporated by reference.
Other curatives known to cure halobutyl elastomers may also be used.
A number of compounds are known to cure BIIR, for example, such as bis
dieneophiies (for example HVA2 - m-phenylene-bis-maleimide) phenolic
3o resins, amines, amino-acids, peroxides, zinc oxide and the like.
Combinations of the aforementioned curatives may also be used.
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The mineral-fiNed halobutyl elastomer of the invention can be admixed
with other elastomers or elastomeric compounds before it is subjected to the
curing with sulphur. This is discussed further below.
Detailed Description of the Invention
s The phrase "halobutyl elastomer(s)" as used herein refers to a
chlorinated or brominated butyl elastomer. Brominated butyl elastomers are
preferred, and the invention is illustrated; by way of example, with reference
to
such bromobutyl elastomers: It should be understood, however, that the
invention extends to the use of chlorinated butyl elastomers.
to Thus, halobutyi elastomers suitable for use in the practice of this
invention include, but are not limited to, brominated butyl elastomers. Such
elastomers may be obtained by bromination of butyl rubber (which is a
copolymer of isobutylene and a co-monomer that is usually a Cq, to Cg
conjugated diolefin, preferably isoprene). Co-monomers other than
is conjugated diolefins can be used, however, and mention is made of aikyl-
substituted vinyl aromatic co-monomers such as C1-C4-alkyl substituted
styrene. An example of such an eiastomer which is commercially available is
brominated isobutylene methylstyrene copolymer (RIMS) in which the co-
monomer is p-methylstyrene.
2o Brominated butyl elastomer typically contains from 1 to 3 weight
percent of isoprene and from 97 to 99: weight percent of isobutylene (based
upon the hydrocarbon content of the polymer) and from 1 to 4 weight percent
bromine (based upon the bromobutyl polymer): A typical bromobutyl polymer
has a molecular weight, expressed as the Mooney viscosity (ML 1 + 8 at
2s 125°C), of from 28 to 55.
For use in the present invention the brominated butyl elastomer
preferably contains in the range of from 1 to 5 weight percent of isoprene and
from 95 to 99 weight percent of isobutylene (based upon the hydrocarbon
content of the polymer) and from 0.5 to 2.5 weight percent, preferably from
30 0.75 to 2.3 weight percent, of bromine (based upon the brominated butyl
polymer).
A stabilizer may be added to the brominated butyl elastomer. Suitable
stabilizers include calcium stearate and epoxidized soy bean oil, preferably
4
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used in an amount in the range of from 0.5 to 5 parts by weight per 100 parts
by weight of the brominated butyl rubber.
Examples of suitable brominated butyl elastomers include Bayer
Bromobutyl~ 2030, Bayer BromobutyiC~ 2040 (BB2040), and Bayer
s Bromobutyl~ X2 commercially available from Bayer Inc. Bayer BB2040 has a
Mooney viscosity (RPML 1+8 @ 125°C according to ASTM D 52-89) of
39 ~
4, a bromine content of 2.0 ~ 0.3 wt% and an approximate molecular weight
Mw of 500,000 grams per mole.
The brominated butyl elastomer used in the process of t!~is invention
to may also be a graft copolymer of a brominated butyl rubber and a polymer
based upon a conjugated diolefin monomer. Our co-pending Canadian
Patent Application 2,279,085 is directed towards a process for preparing such
graft copolymers by mixing solid brominafied butyl rubber with a solid polymer
based on a conjugated diolefin monomer which also includes some C-S-(S)n
is C bonds, where n is an integer from 1 to 7, the mixing being carried out at
a
temperature greater than 50°G and for a time sufficierit to cause
grafting. The
disclosure of this application is incorporated herein by reference. The
bromobutyl elastomer of the graft copolymer can be any of those described
above. The conjugated diolefins that can be incorporated in the graft
2o copolymer generally have the structural formula
Rl Rll
R-CH=C-C=CH2
wherein R is a hydrogen atom or an alkyl group containing from 1 to 8
2s carbon atoms and wherein R1 and R11 can be the same or different and are
selected from the group consisting of hydrogen atoms and alkyl groups
containing from 1 to 4 carbon atoms. Some representative non-limiting
examples of suitable conjugated diolefins include 1,3-butadiene, isoprene, 2-
methyl-1,3-pentadiene, 4-butyl-1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene
30 1,3-hexadiene, 1,3-octadiene, 2,3-dibutyl-1,3-pentadiene, 2-ethyl-1,3-
pentadiene, 2-ethyl-1,3-butadiene and the like. Conjugated diolefin
monomers containing from 4 to 8 carbon atoms are preferred, 1,3-butadiene
and isoprene being especially preferred.
s
CA 02412709 2002-11-25
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The polymer based on a conjugated diene monomer can be a
homopolymer, or a copolymer of two or more conjugated diene monomers, or
a copolymer with a vinyl aromatic monomer.
The vinyl aromatic monomers which can optionally be used are
s selected so as to be copolymerizable with the conjugated diolefin monomers
being employed. Generally, any vinyl aromatic monomer which is known to
polymerize with organo-alkali metal initiators can be used. Such vinyl
aromatic monomers usually contain from 8 to 20 carbon atoms, preferably
from 8 to 14 carbon atoms. Some examples of vinyl aromatic monomers
to which can be so copolymerized include styrene, alpha-methyl styrene,
various
alkyl styrenes including p-methylstyrene, p-methoxy styrene, 1-
vinylnaphthalene, 2-vinyl naphthalene, 4-vinyl toluene and the like. Styrene
is
preferred for copolymerization with 1,3-butadiene alone or for
terpolymerization with both 1,3-butadiene and isoprene.
is The filler is composed of particles of a mineral, and examples include
silica, silicates, clay (such as bentonite), gypsum, alumina, aluminum oxide,
magnesium oxide, calcium oxide, titanium dioxide, tale and the like, as well
as
mixtures thereof. These mineral particles have hydroxyl groups on their
surtace, rendering them hydrophilic and oleophobic. This exacerbates the
2o difficulty of achieving good interaction between the filler particles and
the butyl
elastomer. For many purposes, the preferred mineral is silica; especially
silica prepared by the carbon dioxide precipitation of sodium silicate.
Dried amorphous silica particles suitable for use in accordance with the
invention have a mean agglomerate particle size between 1 and 100 microns,
zs preferably between 10 and 50 microns and most preferably between 10 and
25 microns. It is preferred that less than 10 percent by vcalume of the
agglomerate particles are below 5 microns or over 50 microns in size. A
suitable amorphous dried silica moreover has a BET; surface area, measured
in accordance with DIN (Deutsche Industrie Norm) 66131, of between 50 and
30 450 square meters per gram and a DBP absorption, as measured in
accordance with DIN 53601, of between 150 and 400 grams per 100 grams of
silica, and a drying loss, as measured according to DIN ISO 787111, of from 0
to 10 percent by weight. Suitable silica fillers are available under the
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CA 02412709 2002-11-25
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trademarks HiSil~ 210, HiSil~ 233 and HiSil 243 from PPG Industries Inc.
Also suitable are Vulkasil~ S and Vulkasil~ N, from Bayer AG.
Carbon black is not normally used as a filler in the halobutyl elastomer
s compositions of the invention, but in some embodiments it may tae present in
an amount up to 40 phr. If the mineral filler is silica and it is used with
carbon
black, the silica should constitute at least 55°/a by weighf of the
total of silica
and carbon black. If the halobutyl elastomer composition of the invention is
blended with another elastomeric composition; that other composition may
to contain carbon black as a filler.
The amount of filler to be incorporated into the;halobutyl elastomer can
vary between wide limits. Typical amounts of filler range from 20 parts to 120
parts by weight, preferably from 30 parts to 100 parts, more preferably from
40 to 80 parts per hundred parts of elastomer.
is The organic compound which has at least one hydroxyl group and at
least one basic nitrogen-containing group contains at least one hydroxyl
group, which (without being bound to any particular theory) may react with the
mineral filler, and at least one group containing a basic nitrogen;atom, which
{without being similarly bound) may react with the active halogen in a
2o halogenated butyl elastomer {for example with the active bromine atom in a
brominated butyl elastomer). Functional groups containing -OH may be, for
example, alcohols or carboxylic acids. Functional groups containing a basic
nitrogen atom include, but are not limited to, amines (which can be primary,
secondary or tertiary) and amides. Preferred are primary alkyl amine groups
zs such as aminoethyl, aminopropyl and the like.
Examples of organic compound which has at least one hydroxyl group
and at least one basic nitrogen-containing group which give enhanced
physical properties to mixtures of halobutyl elastomers and especially silica
include proteins, aspartic acid, 6-aminocaproic acid, diethanolamine and
3o triethanolamine. Preferably; the additive should contain a primary alcohol
group and a primary amino group separated by methylene bridged, which may
be branched. Such compounds have the general formula HO-A-NH2; wherein
A represents a C1 to C20 alkylene group, which may be linear or branched.
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More preferably, the number of methylene groups between the two
functional groups should be between 1 and 4. Examples of preferred
additives include mono-ethanolamine and 3-amino-1-propanol.
The amount of the organic compound which has at least one hydroxyl
s group and at least one basic nitrogen-containing group used is dependent
upon the molecularlequivalent weight of each specific compound. One
important factor is the number/weight of nitrogen per unit weight of the
compound. The level of nitrogen may range from 0:1 to 5 parts per hundred
(phr) of halobutyl rubber, preferably from 0.125 to 1 phr and, more
preferably,
to from 0.3 to 0.7 phr: Up to 40 parts of processing oil,: preferably from 5
to 20
parts, per hundred parts of elastomer, may be present. Further, a lubricant,
for example a fatty acid such as stearic acid, may be present in an amount up
to 3 parts by weight, more preferably in an amount up to 2 parts by weight.
The hydrated metal halogenide will have the general formula MX"
is (mH20), in which M denotes for a metal selected from groups 1-16 of the
periodic system of the element according to IUPAC 1985, X is selected from
the group consisting of fluorine, chlorine, bromine and iodine and mixtures
thereof, n is the number of halogenides needed to compensate the positive
charge of the metal ion and m is the average number of water molecules
2o which typically surround the positively charged metal ion. The value m is
typically determined through X-ray structural analysis or through various
gravimetric techniques typically used by those skilled in the art.
Preferred metals are selected from the groups 3 to 12 according to
IUPAC and include Cr, Ni, Co and Fe.
2s Preferred halogenides are chlorine and bromine.
The metal halogenides are usually added in an amount of from 0.1 to
20 phr, preferably of from 2 to 10.
The metal halogenides are especially useful in improving the scorch
safety of compounds comprising primary aminoalcohols.
3o The halobutyl elastomer, filler and additives are mixed together,
suitably at a temperature in the range of from 25 to 200°C. It is
preferred that
the temperature in one of the mixing stages be greater than 60°C, and a
temperature in the range of from 90 to 150°C is particularly preferred.
s
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Normally the mixing time does not exceed one hour; a time in the range from
2 to 30 minutes is usually adequate. The mixing is suitably carried out on a
two-roll mill mixer, which provides good dispersion of the filler within the
elastomer. Mixing may also be carried out in a Banbury mixer, or in a Haake
s or Brabender miniature internal mixer. An extruder also provides good
mixing, and has the further advantage that it permits shorter mixing times. It
is also possible to carry out the mixing in two or more stages. Further, the
mixing can be carried out in different apparatuses, for example one stage may
be carried out in an internal mixer and another in an extruder.
to The order of addition of the different components to the rubber is not
critical, however, it might be advantageous to mix the metal halogenide(s),
the
fillers) and the organic compound which has at least one hydroxyl group and
at least one basic nitrogen-containing group contains at least one hydroxyl
group prior to the addition of the rubber.
is The enhanced interaction between the filler and the halobutyl
elastomer results in improved properties for the filled elastomer. These
improved properties include higher tensile strength, higher abrasion
resistance, lower permeability and better dynamic properties. These render
the filled elastomers particularly suitable for a number of applications,
2o including, but not limited to, use in tire treads and tire sidewalls, tire
innerliners, tank linings, hoses, rollers, conveyor belts, curing bladders,
gas
masks, pharmaceutical enclosures and gaskets. These advantages are
achieved together with an enhancement in scorch safety.
In a preferred embodiment of the invention, bromobutyl elastomer,
2s silica particles; organic compound which has at least one hydroxyl group
and
at least one basic nitrogen-containing group; one or more of the metal
halogenides and, optionally, processing oil extender are mixed ~n a two-roll
mill at a nominal milt temperature of 25°C. The mixed compound is then
placed on a two-roll mill and mixed at a temperature above 60°C. It is
3o preferred that the temperature of the mixing is not too high, and more
preferably does not exceed 150°C, since higher temperatures may cause
curing to proceed undesirably far and thus impede subsequent processing.
The product of mixing these ingredients at a temperature not exceeding
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150°C is a compound which has good stresslstrain properties and which
can
be readily processed further on a warm mill with the addition of curatives.
The failed halobutyl rubber compositions of the invention, and in
particular filled bromobutyl rubber compositions, find many uses, but mention
s is made particularly of use in tire tread compositions. important fieatures
of a
tire tread composition are that it shall have low rolling resistance, good
traction, particularly in the wet, and good abrasion resistance so that it is
resistant to wear. Compositions of the invention display improved resistance
to wear when compared to compounds which contain no organic modifier nor
to hydrated metal halogenide while possessing improved scorch safety. As is
demonstrated in the examples below, compositions of the invention display
improved resistance to wear with enhanced scorch safety.
The filled halobutyl elastomers of this invention can be further mixed
with other rubbers, for example natural rubber, butadiene rubber, styrene-
ls butadiene rubber and isoprene rubbers, and compounds contain these
elastomers.
The invention is further illustrated in the following examples and the
accompanying Figures.
to
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Examples:
Description of tests:
Abrasion resistance: DIN 53-516 (60 grit Emery paper)
s
Cure rheomefry: ASTM D 52-89 MDR2000E Rheometer at 1 ° arc and 1.7
Hz
RPA analysis. 100 °C at a frequency of 30 cpm at strains of 0.5, 1, 2,
5, 10,
20, 50 and 90 °.
io Compound Mooney Scorch. Measurements were conducted at 335 °C using
a small rotor. The t03 value obtained with the small rotor is equivalent to
the
t05 value (large rotor) typically quoted.
Stress-strain. Samples were prepared by curing a macro sheet at 170
°C for
is tc90+5 minutes, after which the appropriate sample was dyed out. The test
was conducted at 23 °C.
Description of Ingredients and General Mixina Procedure:
Hi-Si(C~ 233 - silica - a product of PPG
2o Sunpar~ 2280 - paraffinic oil produced by Sun Oil.
Maglite~ D - magnesium oxide by C.P.Hall
The brominated butyl elastomer, silica, oil,bonding compound end hydrated
metal halogenide were mixed in a 1.57 liter Banbury internal tangential
2s mixture with the Mokon set to 40 °C and a rotor speed of to 77 RPM.
Curatives were then added to the cooled sample witha 6" x 12" mill at
25°C.
Example 1
The effect of FeCl3~xH20 on the degree ofi reinforcement (as denoted by the
M3001M100 values), degree of silica dispersion, DIN abrasion resistance and
scorch safety (as denoted by the t03 times in minutes) in compounds
containing brominated butyl rubber, HiSil~ 233, Maglite~ D and ethanolamine
1I
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was studied. A compound containing only brorninated butyl rubber, HiSil~
233 and Maglite~ D was used as a control. All of the compounds studied
utilized a mixture of 0.5 phr of sulfur, 1.5 phr of zinc oxide and 1.0 phr of
stearic acid as the curative system.
The following levels of FeCl3~xH20 were studied:
(i) 0 phr FeCl3~xHz0
(ii) 2.4 phr FeCl3~xH20
(iii) 4.8 phr FeCl3~xH20
to (iv) 9.7 phr FeCl3~xH20
All compounds, except for the control used 2.2 phr of ethanolamine as the
organic additive containing at feast one amino group and at least one
hyrdroxyl group.
Brominated isoprene isobutylene rubber (BIIR) was mixed with the additive,
60 parts per hundred rubber (phr) of silica filler (HiSil~ 233) in a Banbury
internal mixer under the mixing conditions described above. Identical curative
ingredients (1 phr of stearic acid, 0.5 phr of sulfur, and l.5phr of Zn0) were
2o then added on a cool mill to each of the compounds. The compounds were
then cured for either tc(g0) + 10 minutes at 170 °C (for DIN Abrasion
testing)
or tc(gp) + 5 minutes at 170°C and tested. Table 1 gives the product
compositions, and physical property data for fhe FeCl3~xH20 containing
compounds and for a compound containing no filler bonding agent.
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TABLE 1 Master Batch Mix
Example 1a 1b 1c 1d 1e
Coupling Agent 9.7phr - 4:8 2.4 0 phr Confrol
FeC/9 phr phr FeCl3
FeCl3 FeC73
STRESS STRAIN (DUMBELLS)
Cure Time (min) 25 23 25 19 34
Cure Temperature 170 170 170 170 170
(C)
Dumbell Die C Die C Die Die C Die C
C ~
Test Temperature 23 23 23 23 23
(C)
Hard. Shore A2 Inst.74 76 75 72 76
(pts.)
Ultimate Tensile 15.04 14.45 14.1 17.53 4.9
(MPa)
Ultimate Elongation646 671 515 343 746
(%)
Strain (% Elongation)9.7 phr 4.8 phr 2.4 0 phr Control
FeCl3 FeCls phr FeCl3
FeCl3
25 1.62 1.72 1.78 1.83 1.74
50 1.62 1.65 1.88 2.31 1.57
.
100 1.9 1.8 2.64 3.67 1.62
200 3.26 2.74 5.48 8,24 1.6
300 4.97 4.15 8.34 14.5 1.81
Stress Stress Stress Stress Stress
(MPa) (MPa) (MPa) (MPa) (MPa)
300/100 2.62 2.31 3.16 3.95 1.02
DIN ABRASION
Abrasion Volume 347 336 320 255 TSTM
Loss (mm')
COMPOUND MOONEY
SCORCH
t Value ;03 (min) 5.32 2.55 7.47 9.36 >30
MDR CURE CHARACTERISTICS
MH (dN.m) 32.52 36.43 38.32 41.58 27.05
'
ML (dN.m) 16.84 18.04 16.72 14.05 19.62
'
Delta MH-ML (dN.m) 15.68 18.39 21.6 27.53 7.43
is 1 (min) 1.02 0.96 0.36 0.3 . 1.5
is 2 (min) 1.56 1.32 0.54 0.42 3
t' 10 (min) 1.29 1.24 0.54 0.44 1.13
t' 25 (min) 2.66 2.26 1.2 0.92 2.73
t' 50 (min) 6.14 5.29 3.22 2.82 7.23
Y 90 (min) 20.38 18.34 20.94 13.55 28
t' 95 (min) 25.73 22.23 27.42' 18.08 33.4
Delta t 50 - t'10 4.85 4.05 2.68 2.38 6.1
(min)
RPA Payne Effect
Strain 9.7 ptrr4. 8 2.4 0 phr Control
FeCls phr phr FeCl3
FeCl3 FeCl3
0.28 2030.6 2837.8 1807.4 2442.8
0.98 2212.9 3319.8 2024.6 849.29 2518.6
1.95 2137.9 3158:1 2016.1 937.58 2459.2
4.05 1816.3 2465.5 1736.6 950.73 2110.8
7.95 1360.9 1643.4 1302 881.04 1574.8
16.04 877:94 990.26 859.99 718.01 1029.5
31.95 538.56 581.1 534.26 526.43 642.99
64.03 320.77 336.77 317.42 346.68 387.5
124.99 196.69 204.87 192.01 220.23 235.31
249.98 117.02 124.12 116.12 137.73 135.79
450.03 75.745 79.012 78.495 99.171 81.191
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The data in Table 1 clearly shows the effect of adding FeCl3~xH20 and
monoethanolamine to assist in the dispersion and bonding of the filler in the
brominated: butyl elastomer; especially when compared to the control
compound. The ratio M300IM100 is commonly used as a relative measure of
s the degree of filler reinforcement in an elastomer compound (the higher the
ratio the higher the reinforcement). M300 / M100 for the control (no silane or
FeCl3~xH20) is 1.02 and for FeCl3~xH20 and ethanolamine containing
compounds ranges from 2.31 to 3.95. The stress-strain profile shown in
Figure 1 further emphasizes fihis point.
to The value of the complex modulus (G*) at low stain levels is
commonly taken as a measure of silica dispersion (the lower the G* value at
low strains, the better the silica dispersion). Figure 2 bows the dependence
of this value on the loading of FeCl3~xH20. Importantly, significantly
improved
silica dispersion is seen for compounds which contain ;monoethanolamine and
is FeCl3~xH20 as compared the control compound.
Examination of the DIN Abrasion test data show that the incorporation
of monoethanolamine and FeCl3~xH20 into these compounds significantly
improves wear. The control compound was far to soft to be measured
(TSTM).
2o The t03 time obtained from a Mooney Scorch measurement is taken to
be representative of the scorch safety possessed by a rubber pre-vulcanizate.
As the t03 increases, so does the processability. From the data presented in
Table 1, it is clear that the incorporation of mixtures of monoethar~olamine
and
FeCl3~xH20 into these compounds improves the scorch safety (lowers the t03
2s times) when compared to the control compound or to the compound which
contains only monoethanolarrmine. This particular observation illustrates the
role of FeCl3~xH20 on the scorch safety, and thus processability, of these
compounds.
3o Example 2
The effect of NiCl2~xH20, CrCl3~xH20 and CoCl2~xH20 on the degree of
reinforcement (as denoted by the M3001M100 values), degree of silica
dispersion, DIN abrasion resistance and scorch safety (as denoted by the t03
14
CA 02412709 2002-11-25
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times in minutes) in compounds containing brominated butyl rubber, HiSil~
233, Magiite~ D and ethanolamine was studied. A compound containing only
brominated butyl rubber, HiSil~ 233, monoethanolamine and Maglite~ D was
used as a control. All of the compounds studied utilized a mixture of 0.5 phr
s of sulfur, 1.5 phr of zinc oxide and 1.0 phr of stearic acid as the curative
system.
The following levels of hydrated metal halogenides were studied:
(i) 0 phr (Control)
(ii) 8.5 phr NiCl2~xH20
to (iii) 9.6 phr CrCl3~xH20
(iv) 8.6 phr CoCl2~xH20
All compounds used 2.2 phr of ethanolamine as the organic additive
containing at least one amino group and at least one hydroxyl group.
is Brominated isoprene isobutylene rubber (BIIR) was mixed with the
additive, 60 parts per hundred (phr) of silica filler (HiSil~ 233) in a
Banbury
internal mixer under the mixing conditions described above. Identical curative
ingredients (1 phr of stearic acid, 0.5 phr of sulfur, and 1.5 phr of Zn0)
were
then added on a cool mill to each of the compounds. The compounds were
2o then cured for either t~(90) + 10 minutes at 170 °C (for DIN
Abrasion testing)
or t~(90) + 5 minutes at 170 °C and tested. Table 2 gives the product
compositions, and :physical property data for the hydrated metal halogenide
containing compounds and for the control compound which contains only
monoethanolamine.
2s That data in Table 2 clearly shows the effect of adding a hydrated
metal halogenide to BIIR/HiSillmonoethanolamine compounds. Importantly,
significant differences are seen on varying the metal center. . This would
indicate, as expected, a dependence on the degree ofinteraction~between the
monoethanolamine and the metal center to the nucleophilicity of that metal
3o center.
As the data in Table 2 illustrates, the interaction of the hydrated metal
halogenides with the monoethanolamine suppresses the function of the
monoethanoiamine as a dispersing and linking agent for silica within BIIR.
is
CA 02412709 2002-11-25
POS 1109 FF
However, it is important to note the improvements in t03 times which are
observed when the hydrated metal halogenides are incorporated into the
rubber compound (Figure 3).
16
CA 02412709 2002-11-25
POS 1109 FF
TABLE 2
Example 2a 2b 2c 2d
Coupling Agenf None 8:5 NiClz9.6 CrCls8.6 CoClz
(xHZO) (xHzO) (xHZO)
STRESS STRAIN (DUMBELLS)
Cure Time (min) 19 21 28 21
Cure Temperature 170 170 170 170
(C)
Dumbell Die C Die C Die C Die C
Test Temperature 23 23 23 23
(C)
Hard. Shore A2 72 71 62 72
Inst: (pts.)
Ultimate Tensile 17.53 13.92 12.15 13.48
(MPa)
Ultimate Elongation343 863 1012 897
(%)
Strain (% Elongation)None 8.5 NiClz9.6 CrCl38.6 CoClz
(xH20) (xH20) (xHzO)
25 1.83 1.51 1.21 1.59
50 2.31 1.45 1.14 1:54
100 3.67 1.53 1.15 ~ 1.52
200 8.24 2.2 1.51 1.9
300 14.5 3.39 2.26 2.74
Stress Stress Stress Stress
(MPa) (MPa) (MPa) (MPa)
300/100 3.95 2.22 1.97 1.80
DIN ABRASION
Abrasion Volume 255 345 399 374
Loss (mm')
COMPOUND MOONEY
SCORCH
t Value t03 (min) 1.36 2.91 26:03 3.15
MDR CURE CHARACTERISTICS
MH (dN.m) 41.58 29.27 22.58 30.65
ML (dN.m) 14.05 13.67 13.19 14.34
Delta MH-ML (dN.m)27.53 15.6 9.39 16.31
is 1 (min) 0.3 1.62 2.58 1.2
is 2 (min) 0.42 2.4 4.14 1.74
t' 10 (min) 0.44 2.03 2.5 1.51
t' 25 (min) 0.92 3.78 4.82 2.92
t' S0 (min) 2.82 7.13 11.25 6.14
t' 90 (min) 13.55 16.24 32:9 16.2
t' 95 (min) 18.08 18.68 39.24 18.99
Delta t30 - t'10 2:38 5.1 8.75 4.63
(min)
RPA Payne Effect
Strain None 8.5 NiClz9.6 CrCl38.6 CoClz
(xH20) (xH20) (xHzO)
0.98 849.29 1721.4 1518.8 1967.4
1.95 937.58 1840.3 1770.9 2080.3
4.05 950.73 1554.1 1561.1 1692
7.95 881.04 1132.8 1148.8 1189
16.04 718.01 734.77 726.52 752.33
31.95 526.43 457.16 431:18 461.02
64.03 346.68 279.81 243.56 279.01
124.99 220.23 180.07 139.64 178.54
249.98 137.73 116.09 78.85 115.1
450.03 99.171 77.572 49.298 76.902
17
