Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1~4~6
1. MD 29907
:
. .
This invention relates to improved siliceous filler
compositions.
Compositions have been proposed which comprise a
particulate siliceous filler mixed with an organo-silicon
compound which is capable of coupling to the filler
and which is preferably also capable of reacting with a
polymer. Such compositions are particularly suitable
for mixing with a polymer to form a polymer composition
(especially a rubber composition) because the presence
of the organo-silicon compound leads to an improvement
in certain properties of the polymer composition in
comparison with the properties of a polymer composition
which contains a siliceous filler but which does not
contain an organo-silicon compound.
It is desirable to be able to form a so-called "master-
batch" of mixed siliceous filler and organo-silicon
compound, which contains a proportion of organo-silicon
compound to siliceous filler which is greater than the
`' proportion required when the siliceous filler composition
is incorporated into the polymer composition.
The "master-batch" siliceous filler composition may
;'- be mixed with further siliceous filler so as to provide
i a proportion of organo-silicon compound to siliceous
filler which is desired in the polymer composition.
.',;
~.
'
1~ 2~ 2. MD 29907
This may be done before, during, or after incorporating
the master batch into the polymer composition. We find,
however, that using a master-batch and diluting it with
further siliceous filler suffers from a disadvantage
when the master-batch has been stored for some time.
Thus, certain properties of the resultant polymer
; composition (and, in particular, tensile modulus properties)
are inferior to the properties of a polymer composition
which incorporates a siliceous filler and an organo-silicon
compound freshly mixed in the proportions desired,
either (a) by mixing the polymer with the siliceous
filler and with the organo-silicon compound or (b) by
mixing the polymer with a siliceous filler composition
which has itself been made by directly mixing siliceous
filler and organo-silicon compound in the proportions
desired in the polymer composition.
; We have now found a way of overcoming the afore-
mentioned disadvantage.
; The present invention provides a filler composition
comprising:-
- (A) an organo-silicon compound containing at least
one group which is capable of reacting with a
siliceous filler and at least one non-
hydrolysable organic group attached directly
or indirectly to Si,
~B) an organic stabiliser component as hereinafter
defined which is capable of associating with the
surface of a siliceous filler, and
(C) a finely divided particulate siliceous filler.
We find the presence of the organic stabiliser com-
ponent B in the filler composition enables the composition
to be stored for prolonged periods of time, and sub-
sequently to be mixed with a polymer and with further
siliceous filler in an amount to give the desired
~ 1~ 24426
3. MD 29907
proportion of organo-silicon compound to siliceous
filler, with little or no adverse affect on the
properties of the resultant polymer composition.
;~ Our invention is especially applicable to master-
batches which are to be used in conjunction with
additional filler, but can also be applied to stabilise
mixtures to which no further filler need be added.
The organo-silicon compound is suitably a compound
containing at least one group - Si (X)n where X
(which may be the same or different) is H, OH or OR,
where R is a hydrocarbon or substituted hydrocarbon
group, and n is 1, 2 or 3. Preferred organo-silicon
compounds are those which contain at least one group
; OR. R is preferably a lower alkyl group, for example
an alkyl group containing from 1 to 4 carbon atoms,
i.e. methyl, ethyl, propyl or butyl. R may bear
substituent groups, in which case it is preferred that
the substituents be neither acidic nor basic in nature.
Further preferred organo-silicon compounds are those
containing the group -Si(OR)nY3 n wherein R has the
^ meaning given above and Y represents a hydrocarbon
; substituent, especially a lower alkyl group of 1 to 4
carbon atoms. The organo-silicon compound may contain
:' more than one group -Si(X)n or -Si(OR)nY3 n'
which may be the same or different.
` The non-hydrolysable organic group attached to silicon
: in the organo-silicon compound is preferably capable
~r~: of reacting with the polymer in the polymer composition.
For example, this organic group may contain unsaturation,
especially ethylenic unsaturation, and it is suitably
derived from a polymeric molecule. Where the filler
composition of the invention is to be incorporated
into a curable rubber composition it is especially
convenient for the non-hydrolysable organic group to
contain at least one ethylenically unsaturated hydrocarbon
.
~24~26
4. MD 29907
group which is capable of taking part in the rubber-curing
reaction. Thus, the non-hydrolysable organic group may
be part of a polydiene structure. Examples of polydiene
structures are those of polymers and copolymers
derived from one or more dienes, of which the most
conveniently available is butadiene, although others
may be used if desired (for example isoprene and
chloroprene and mixtures thereof). Examples of other
compounds which may be copolymerised with the diene or
dienes include a wide range of vinyl monomers, for
example, styrene, acrylonitrile, and mixtures thereof.
The non-hydrolysable organic group in the organo-
silicon compound may contain sulphur. This is par-
i~ ticularly convenient where the filler composition of
the invention is to be incorporated in a sulphur-curable
rubber composition, because the sulphur in the organo-
silicon compound may take part in the curing reaction
:~ and provide a link be~ween the organo-silicon compound
and the rubber.
The non-hydrolysable organic group in the organo-
silicon compound is preferably one which has a molecular
:- weight in the range up to 500,000. Where the organic
group is a polymer it preferably has a molecular weight
in the range 200 to 50,000, especially in the range
1000 to 10,000. The non-hydrolysable organic group may
be attached directly or indirectly to the silicon atom
or atoms.
The term "non-hydrolysable" is used in the sense of
meaning that the group as a whole is not removed from
the silicon by hydrolysis.
Bxamples of organo-silicon compounds wh-ch may be used
in the composition of our invention include:
(a) Compounds comprising an organic molecular chain
structure bearing at least one mono-alkoxy or
di-alkoxy silyl group or corresponding substituted
~ Z44~26
5. MD 29907
,
alkoxy or di-alkoxy silyl groups. These compounds
may most conveniently have an organic molecular
chain structure derived from a polydiene (for
example a polybutadiene) and may be made by known
silylating methods, for example by reaction of a
polydiene with a hydrosilane containing the silyl
group which it is desired to introduce into the
molecule (conveniently in the presence of a
; catalyst, for example a platinum-containing
catalyst).
(b) Compounds comprising an organic molecular chain
structure bearing at least one tri-alkoxy-silyl
' group. Most conveniently these may have an
organic molecular chain structure derived from a
polydiene, for example polybutadiene. Such
; compounds are included among the many contained
within the definitions in US Patent No 3759869 of
- SkP:st.
(c) Compounds containing a mono-alkoxy, di-alkoxy or tri-
alkoxy silyl group attached, by way of a short
.~i
organic chain, to a sulphur-bearing group which
;; may be for example a sulphydryl group (SH), a
polysulphide group or the like. An example of
this latter type of organo-silicon compound is a
compound having the structure HS (CH2)n Si (OR)3
where n is an integer (conveniently an integer in
- the range 2 to 10, for example 3) and R is a
hydrocarbon or substituted hydrocarbon group,
for example a lower alkyl group containing from 1
to 4 carbon atoms, for example methyl or ethyl.
A further example is a compound having the
structure
[ )3si(CH2)n] 2Sx
6 ~2~4~6 MD 29907
where n and R have the meanings indicated above,
and x is at least 2, e.g. 2 to 4 or even higher.
Specific examples of such compounds are bis-(gamma-
triethoxysilyl propyl) tetrasulphide and gamma-.nercapto-
propyl trimethoxy silane.
The number of silicon atoms in the organo-silicon
compound is preferably such as to provide at least one
silicon atom for each 3000 of the molecular weight of
,~ the non-hydrolysable organic group.
The organic stabiliser component B in the filler com-
position of the invention tan organic compound capable
; of associating with the surface of a siliceous filler)
is a compound which contains at least one polar
group. Suitable polar groups include ether oxygen atoms,
amino nitrogen atoms (including those with and without
a substituent on the nitrogen atom), hydroxyls, and
; ketone groups. The number of such polar groups in the
organic compound may vary, but it may be as low as in
~; the range 1 to 16, but may be much higher, for example
up to 100 or even more. The optimum number may
depend on the nature of the organo-siliccn compound,
`; and, where the latter compound contains a group
-Si(X)n, on the value of n.
Very effective results are obtained when the stabiliser
component B is a polyether compounds. Especially
useful polyether compounds are substantially linear
polyethers. The most convenient examples of such
compounds are the polymers and copolymers of alkylene
oxides, for example those derived from ethylene oxide
and/or propylene oxide. Such polymers, sometimes
called polyethylene glycols or propylene glycols, or
even just "polyethers", may optionally have an organic
end group etherifying one or both of the terminal
oxygen atoms of the molecule. The molecular weight of
the polymer compounds is preferred to be in the range
4~6
` 7. MD 29907
106 to 10,000, though higher and lower molecular weights
may be used if desired.
Diethylene glycol and several polyethylene glycols
are especially useful additives for this purpose, as
` 5 they are well known to be useful in rubber compounding
` and therefore have no troublesome side-effects in the
final product.
Copolymers of ethylene oxide and/or propylene oxide
` which may also be mentioned include the condensates of
10 the alkylene oxides (especially ethylene oxide) with a
variety of organic compounds, (especially an organic
hydroxy compound) for example alcohols (especially
aliphatic higher fatty alcohols of 8 to 20 carbons),
phenols and alkylated phenols, aliphatic carboxylic
r 15 acids, aliphatic carboxylic amides, and mixtures
thereof. Many such products are available in commerce
;, as surfactants or dispersants.
Another useful group of polar compounds comprises
aliphatic poly-hydroxy compounds, especially those
20 which are liquid and of molecular weight up to
about 300. Examples of these include glycerol and
hexane-triol.
The finely-divided particulate siliceous filler for
use in the compositions of the invention may have any
25 form conventional in the art as suitable for a filler,
may have a wide variety of particle shapes and sizes,
and may be of natural or synthetic origin. Thus, the
filler may, for example have an average particle
diameter less than 100 nm or a specific surface area
30 greater than 25 m2 per gram, though we prefer that
the average particle diameter should be in the range
- 40 Angstrom to 1000 Angstrom, for example about 200
Angstrom.
Most commonly the filler will be of a substantially
spherical shape, though it may if desired be of
~ 2~4~ MD 29907
fibrillar or laminar form, for example the residual
pseudomorphs remaining after silicate minerals (for
example vermiculite, chrysotile asbestos and the like)
are dispersed and treated with acids to remove cations.
Most conveniently the filler is in the form of a
finely divided, free-flowing powder, and this is the
form in which such materials are usually available in
commerce. The filler may be dried, for example by
heat, before use in the compositions of our invention,
in order to drive off all or part of adsorbed water.
Chemically, suitable siliceous filler particles may
; consist of substantially pure silica or may contain
silica together with a proportion of one or more other
metal oxides, for example acidic oxides, eg titania,
or metal oxides capable of forming silicates, eg
calcium, magnesium, aluminium and combinations of
these. They may consist of-a silicate, provided
the silicate is one which is suitable for use as a
filler, for example if it is insoluble in water.
Suitable silicates include clays which can be produced
in a sufficiently finely divided form to serve as
fillers.
We strongly prefer that the siliceous particles con-
tain free silanol groups at their surface, either by
virtue of their constitution or my modification during
manufacture of the material into particles of desired
dimensions. We therefore prefer that the siliceous
particles consist predominantly of silica and we
especially prefer that they consist of substantially
pure silica itself. A very suitable material is that
known as precipitated silica, which may be made for
example by precipitating silica from aqueous solutions
of alkali metal silicates by acidification. If
:
9 l~,Z ~42 6 MD 29907
desired, other forms of silica may be used, for
example that made during burning silicon tetrachloride
in air (commonly described as "fumed silica").
~i The p.oportions of the components of the filler com-
position of the invention may vary but they are
usually in the range:-
(a) S to 150 parts by weight of organo-silicon
; compound for every 100 parts by weight of the
siliceous filler, and
(b) 1 to 60 parts by weight of organic stabiliser
component capable of associating with the surface
of a siliceous filler for every 100 parts by
weight of the siliceous filler.
In order that use of the organic stabiliser component
B should result in a substantial advantageous effect
it is preferred that the latter be present in the com-
position in a proportion of at least 5 parts by weight
for every 100 parts by weight or organo-silicon
compound, and preferably in a proportion in the range
10 to 50 parts by weight for every 100 parts by weight
of organo-silicon compound.
The optimum proportions of the components of the
composition is best determined by simple trial, and we
prefer to use sufficient of the filler to result in
the composition being a free-flowing powder. The mode
of mixing of the components may need to be adapted to
suit the particular components used, for example a
high-shear blender may be most suitable and it may be
helpful to apply some heat. Especially convenient is
the use of a solvent to assist the dispersion of the
organic materials (components A and B) over the
particulate filler C; a suitable solvent for this is
the solvent which may have been used for carrying out
the preparation of the organo-silicon compound. Thus
it is preferred to make the organo-silicon compound in
~244~
10. MD 29907
an organic solvent, dissolve the organic stabiliser
component B in the resulting solution, and then mix
the solution with filler and evaporate off the solvent.
Alternatively, the components of the composition may
be mixed in a suitable blender, eg in a ball mill.
~ This may be done in the absence or in the presence of
; a solvent.
Although some reaction of the organo-silicon compound
with the siliceous filler may take place during
; 10 the production of the composition of the invention it
is preferred that the extent of reaction be kept to a
minimum. The conditions used in the blending of the
components of the composition, and especially the
temperature used, should be chosen with care so as to
minimise the extent of premature reaction.
The composition of the invention may contain other
; components, for example, one or more antioxidants.
The proportions of antioxidant may suitably be in the
range 0.1 to 5 parts by weight of antioxidant for
every lO0 parts by weight of organo-silicon compound.
In a further embodiment of the present invention
there is provided a polymer composition comprising
at least one organic polymer and a filler composition
as hereinbefore described. The polymer composition
suitably comprises at least 0.4 part by weight of the
filler composition for every lO0 parts by weight of
the organic polymer, and preferably 2 to 40 parts by
weight of the filler composition for every lO0 parts
by weight of the organic polymer.
The polymer composition may be produced by blending
the organic polymer and the filler composition by
known methods, for exa,n~le, by using a ball mill, and
especially in the case where the organic polymer is a
rubber, by using a multi-roll mill, eg a twin-roll
mill. The polymer composition may also include
~24~26
11. MD 29907
additional siliceous filler in an amount chosen to
achieve a proportion of organo-silicon for example,
from 1 to 20 parts by weight of organo-silicon compound
- for every 100 parts by weight of siliceous filler,
which is desired in the polymer composition. This
additional siliceous filler in the polymer composition
may be the same as the siliceous filler in the filler
composition, but it may be different if desired.
; The polymer composition suitably contains a total
of from 1 to 150 parts by weight siliceous filler for
- every 100 parts by weight of organic polymer.
The organic polymer may be a thermoplastic organic
polymer, for example:-
a polyolefin, eg polyethylene, polypropylene or
an olefin copolymer;
an acrylic polymer, eg poly(methyl methacrylate);
a halogen-containing polymer, eg poly(vinyl chloride)
or poly(vinylidene chl^ride).
Advantageously, the polymer may be a curable (especially
;~ 20 vulcanisable) polymer and preferably an elastomer.
The organic polymer is preferably caused to react
with the non-hydrolysable organic group in the organo-
silicon compound, for example by including a free-radical
generator in the polymer composition and by heating
the composition to cause reaction. In order that
reaction may readily be effected it is preferred that
the non-hydrolysable organic group in the organo-silicon
compound contains ethylenic unsaturation. Alternatively,
where the organic polymer is a sulphur-curable rubber
the non-hydrolysable organic group in the organo-silicon
compound may contain one or more sulphur atoms which
may take part in the curing reaction and provide a
link between the organo-silicon compound and the
rubber.
~L~.29;~26
12. MD 29907
Where the organic polymer is a curable rubber it may
be a natural or synthetic rubber, for example, a
polymer containing polymerised diene units, for
- example polymerised butadiene, isoprene or chloroprene.
The diene may be copolymerised with each other and/or
with non-dienes. Suitable rubbers include polybutadiene,
polyisoprene, polychloroprene, acrylonitrile-butadiene
rubbers, and styrene-butadiene rubbers. The polymer
composition may contain materials conventional in the
rubber curing art, for example, sulphur and accelerators.
Under the conditions coventionally used for curing the
rubber it will generally be found that where the
non-hydrolysable organic group of the organo-silicon
compound contains unsaturation or contains sulphur it
will react with the rubber molecule, especially in the
presence of conventional rubber-curing materials.
Also the conditions of the rubber curing reaction will
generally be such as to cause reaction between the
siliceous filler and the organo-silicon compound.
The testing or demonstration of the stabilising
efficiency of the organic stabilising component can be
shown by several different tests. The actual effect
in making a final polymer composition is most direct
evidence, but we find that an excellent test comprises
subjecting a mixture of the organo-silicon compound,
the filler and the stabiliser to standard conditions
of temperature and humidity, and measuring the evolution
of alkanol (eg ethanol) when the organic-silicon
compound contains alkoxy groups. The composition will
evolve alkanol very much less rapidly in the presence
of the stabiliser. This test is described more fully
as follows:-
1 part by weight of siliceous filler to be used inthe composition of the invention is mixed with 1 part
by weight of an organo-silicon compound (for example a
~Z4~6 13 MD 29907
- diethoxy methyl silyl polybutadiene containing on
; average 1 atom of silicon for every 10 molecules of
butadiene) and the mixture is placed in a closed
container containing air at 35% relative humidity at a
temperature of 25C and the amount of ethanol released
in 24 hours is measured, eg by gas-liquid chromatography.
The release of ethanol indicates reaction between the
organo silicon compound and the siliceous filler. 0.4
part by weight of organic compound under test is then
mixed with 1 part by weight of siliceous filler, the
mixture is then mixed with 1 part by weight of the
diethoxy methyI silyl polybutadiene, the resultant
mixture is placed in a closed container containing air
at 35% relative humidity at a temperature of 25C,
and the amount of ethanol released in 24 hours is
measured. A preferred organic compound suitable for use
in the filler composition of the present invention is a
compound which reduces the amount of ethanol released
in 24 hours to one tenth or less of that which is
released in the absence of the organic compound.
An alternative test, which correlates w~ll with the
one already described, comprises maintaining the
composition under simulated storage conditions (standard
temperature and humidity) for a period and then
measuring the loss of solubility of the organo-silicon
compound component. A suitable solvent for this test
is toluene or methanol, and the more efficient the
stabiliser is, then the smaller will be the amount of
organo-silicon compound which cannot be recovered from
the mixture by extraction.
The invention is illustrated by the following
; Examples in which all parts and percentages are
expressed by weight unless otherwise stated.
h~.2~4Z~ 14. MD 29907
EXAMPLE 1
1 part of a commercially available grade of
precipitated silica filler, containing 0.7% sodium
ions and 0.7% alumina calculated on the dried material,
was mixed with 0.48 parts of diethylene glycol and to
this mixture 1 part of polybutadiene silicate* was added.
The components of the mixture were thoroughly blended
; by ball-milling the mixture for 2 hours to produce a
fine particle size product which will be referred to
as the masterbatch.
(*The polybutadiene silicate was prepared by reacting
13.4 parts of methyl diethoxy silane with 54 parts of
polybutadiene (48% 1:2, 52% 1:4) of molecular weight
3000 in toluene for 1 hour at 90 to 100C in the
presence of chloroplatinic acid catalyst. The toluene
- was subsequently evaporated and the polybutadiene
silicate was recovered in the form of an oil).
Immediately after preparation of the masterbatch
15.6 parts of the masterbatch were blended on a mill
with 100 parts of styrene-butadiene rubber (SBR 1509)
and then the following components were added in the
order stated,
0.8 part of 'Vulcafor' M BTS (mercaptobenzthiazole),
1.2 parts of 'Vulcafor DPG' (diphenylguanidine),
2 parts of zinc oxide,
2 parts of stearic acid,
0.5 part of triethanolamine,
43.6 parts of precipitated silica, and
2,5 parts of sulphur.
The rubber composition was thoroughly blended on the
twin-roll mill.
Sheets of the rubber composition were then cured by
heating in a hydraulic press at a temperature of
160C for 8 minutes and the tensile properties of the
resultant sheets were measured. The results are given
in Table 1.
z~
15. MD 29907
In a further experiment the above described procedure
was followed to produce a cured rubber composition
except that the master batch was blended with the
styrene-butadiene rubber and with the other components
of the rubber composition 37 days after the preparation
of the master batch. The tensile properties of the
cured rubber sheets are given in Table 1.
By way of comparison a master batch was prepared from
a mixture of 1 part of polybutadiene silicate and 1
part of precipitated silica by ball-milling the
mixture for 2 hours. The diethylene glycol was
omitted.
In a first comparative experiment the master batch
was blended immediately after its preparation with a
styrene-butadiene rubber and with the other components
of the rubber composition following the above described
procedure, and in addition with 3 parts of diethylene
glycol, and sheets of the rubber composition were
cured by heating in a hydraulic press at a temperature
of 160C for 8 minutes and the tensile properties of
the resultant sheets were measured. The results are
given in Table 1.
In a second comparative experiment the master batch
; prepared from polybutadiene silicate and precipitated
silica was allowed to stand for 37 days and then
blended with the other components of the rubber
; composition following the procedure described above in
the first comparative experiment. The properties of
the sheets prepared by heating the sheets in a hydraulic
press at a temperature of 160C for 8 minutes are
given in Table 1.
It can be seen that the master batch which contains
diethylene glycol, when allowed to stand for 37 days
before use and then incorporated in a rubber results in
superiGr tensile modulus properties than does a master
batch which was prepared in the absence of diethylene
glycol and which had also been allowed to stand for
37 days before use.
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17. ~ ~ ~ 442 6MD 29907
.:
EXAMPLE 2
Masterbatches were prepared by mixing 1 part of a
commercially available precipitated silica filler (as
specified in Example 1) with 1 part of bis-(gamma-
triethoxysilylpropyl) tetrasulphide and 0.4 part of a
stabiliser. J
The stabilisers used were:
Masterbatch A : Polyethylene glycol, molecular weight
380-420 ("PEG 400")
Masterbatch B : Polyethylene glycol, molecular weight
3800-4800 ("PEG 4000")
" C : Polyethylene glycol, molecular weight
950-1050 ("PEG 1000") (50%) plus a
condensate of mixed cetyl and oleyl
alcohols with about 8 molecular
proportions of ethylene oxide (50%).
" D : No stabiliser (for purposes of com-
; parison).
The silane compound and the stabilisers were mixed
together and then stirred into the silica, and thoroughly
mixed by ball-milling for 1 hour to produce a product
; of small particle size. In the case of masterbatch
C, 2.5 parts of toluene were added to assist homogeneity
and finally removed by evaporation at 30 to 50C.
These masterbatches were then exposed, in shallow
; trays, to "tropical humidity conditions" (38C and 90%
relative humidity) for seven days. They were then
used to prepare silica-filled rubber vulcanisates,
whose cure and tensile properties were then measured
by established methods.
The rubber formulations used were as follows, in
which it is to be noted ~hat further amounts of the
stabiliser components are added because these are of a
type known to have beneficial effects in silica-filled
rubber formulations and it was desired to make the
pairs of composit ~s properly comparable.
1~2442G
18. MD 29907
Ingredients Rubber Mixes
2 3 4 5 6
Rubber SBR 1509 100 100100 100 100100
Silica Filler 48 48 48 48 48 48
"Ultrasil" VN3
10 Zinc Oxide 2 2 2 2 2 2
Stearic acid 2 2 2 2 2 2
Mercapl:obenzthiazole 0.8 0.8 0.80.8 0.8 0.8
Diphenylguanidine1.2 1.21.2 1.2 1.21.2
Sulphur 2.5 2.52.5 2.5 2.52.5
. 15
Masterbatch A 4.8
Masterbatch D - 4.0
"PEG 400" 1.2 - 2.0
20 Masterbatch B - - 4.8
Masterbatch D - - - 4.0
nPEG 4000" -- -- 1.2 2.0
Masterbatch C - - - - 4.8
25 Masterbatch D - - - - - 4.0
"PEG 1000" - - - - 1.62.0
Condensate of cetyl/ - - - - - 0.4
oleyl alcohols
with 8 mol
ethylene oxide
~L~2~Z6
19. MD 29907
Rubber Mixes
1 2 3 4 5 6
Minimum Viscosity,9 10 9 10.5 8 10
Induction Time 2.4 2.3 2.4 2.3 2.0 2.4
(minutes)
Peak Cure State 100 102 94 90 97 94
10 95% Cure 95.4 97.489.7 86.1 92.689.8
Time to 95% Peak9.5 9.511.0 9.3 10.3 8
' Cure time (160C) 10 1011.5 9.7 10.8 8.5
. .
15 Tensile Strength kg/cm2160156 157 148 159 i44
;~ Elongation to Break %573 595 577 636 555 638
Modulus at 300% kg/cm270 66 70 58 73 54
Tear Strength kg/mm 5.4 4.8 4.9 4.9 4.8 4.8
These results show that all the stabilised masterbatches
produce better vulcanisates than the unstabilised ones.
EXAMPLE 3
Masterbatches of a precipitated silica filler (as sold
~' under the name "Ultrasil" VN3), a silane coupling
agent and a stabiliser were made by mixing the silane
with the stabiliser, and then with the filler and then
ball-milling for 30 minutes. The silane was bis-(gamma-
triethoxysilyl propyl) tetrasulphide, and the proportions
of stabiliser (in parts per 2 parts of the silane-silica
mixture) are listed in the table below.
~244~26
20. MD 29907
The masterbatches were then exposed to warm, humid con-
ditions (38C at90% relative humidity) in shallow
trays for 7 days. Then their stability was measured
by determining the weight of material in them which
remained extractable by toluene. This was done by
stirring them with 100 parts of toluene and then
filtering the mixture and evaporating the filtrate to
constant weight at 40 to 45C in a vacuum oven. The
weight of extracted material was corrected by deducting
the weight of stabiliser used (assuming 100% extraction
of the stabiliser) and converted to percentage recovery
of the total silane originally present.
; Stabiliser Parts used % Recovery of
silane
nPEG 400" 0.4 75
"PEG 400" - 0.2 )
Condensate of cetyl/oleyl ) 84
alcohols with 8 mol 0.2 )
20 ethylene oxide
"PEG 1000" 0.4 72
"PEG 4000" 0.4 100
Condensate of cetyl/oleyl
alcohols with more than 8 0.4 82
25 mol ethylene oxide
Condensate of cetyl/oleyl
alcohols with 8 mol 0.1 85
ethylene oxide
NONE (for comparison) 43
..
~Z~4Z6 21. MD 29907
EXAMPLE 4
The procedure of Example 3 was repeated using hexane
triol and glycerol respectively as the stabiliser.
The solvent used for the extraction test was methanol
instead of toluene. The results obtained were:
Stabiliser Parts used % Recovery of silane
Hexanetriol 0.4 96
Glycerol 0.4 83
EXAMPLE 5
! 10 Masterbatches were prepared by the method described in
Example 3, except that the silane used was a polybuta-
; diene silicate (silylated polybutadiene) prepared as
described in Example 1 from a polybutadiene of molecular
weight 5000 (20% 1:2, 80% 1:4).
- 15 The stability of the masterbatches was measured by com-
paring the amounts of ethanol evolved from them and
- from a corresponding masterbatch containing no stabiliser
ingredient.
The test was carried out by storing a small sample
(1.0 gm of unstabilised mix or 1.2 gm of a stabilised
mix) in a sealed l-litre container containing air
under ambient conditions. The evolved ethanol was
then measured by Gas-Liquid Chromatography (GLC)
techniques, and the results are summarised in the
table below. The ethanol released is measured in
terms of the peak height on the GLC recorder chart.
The proportion of the stabiliser used in each case
was 0.4 part per 1 part of silica and 1 part of silane.
Stabiliser Ethanol evolved
after 25 hours.
Condensate of fatty alcohol with Less than 1
ethylene oxide (low proportion)
Condensate of cetyl/oleyl alcohols Less than 1
with ethylene oxide
~ 24~Z6
22. MD 29907
Condensate of monylphenol with 5.5 Less than 1
mol of ethylene oxide
Condensate of fatty alcohol with Less than 1
ethylene oxide (high proportion)
5 Condensate of nonylphenol with Less than 1
ethylene oxide (higher than 5.5 mol)
NONE (for comparison) 40
: EXAMPLE 6
Masterbatches were prepared and measured for stability
by the methods described in Example 5 except that the
silane used was gamma-mercaptopropyl tri-methoxy-
silane and the measurements were made to determine
evolved methanol. The results were as follows:
Stabiliser Methanol evolution after .
4 hours 24 hours
Condensate of fatty alcohol
with ethylene oxide (low
proportion) 310 420
"PEG 400" 500 600
20 NONE (for comparison) 740 780
(Note: This silane is very reactive, but even so the
reduction in methanol evolution is marked).
EXAMPLE 7
Masterbatches were prepared and measured for stability
by the methods described in Example 5 except that the
silane used was bis-(gamma-triethoxysilyl-propyl)
tetrasulphide. They were also repeated using a
semi-reinforcing clay filler (HEWP, from English China
Clays) of surface area 30 square metres per gram. The
results were as follows:
.
l~Z4~26
23. MD 29907
Stabiliser Ethanol evolution after
24 hours
(Silica (Clay
filler) filler)
5 Condensate of fatty 34 70
alcohol with ethylene
; oxide (low proportion)
"PEG 400" 20 55
NONE (for comparison) 74 185
10 EXAMPLE 8
The procedure of Example 1 was repeated, except that
a commercially available condensate of a fatty alcohol
and ethylene oxide was used in place of the diethylene
glycol to prepare the masterbatch, and the polybutadiene
silicate was replaced by bis-(gamma-triethoxysilylpropyl)
tetrasulphide. The results obtained were:
Days Ageing Properties of With Without
Under "Tropical Cured Rubber Stabil- Stabil-
Humidity Con- Sheet iser iser
ditions"
O Tensile Strength Kg/cm2165 167
. Elongation % 689 651
Tensile Modulus
100% Kg/cm222 24
200% Kg/cm38 40
300% Kg/cm258 62
6 Tensile Strength Kg/cm2155 147
Elongation % 656 751
Tensile Modulus
100% Kg/cm222 20
200% Kg/cm238 34
: 300% Kg/cm257 49
-
.
: , : . .
~L~24426
24. MD 29907
Days Ageing Properties of With Without
Under "Tropical Cured Rubber Stabil- Stabil-
Humidity Con- Sheetiser iser
; ditions"
42 Tensile Strength Kg/cm 150 117
Elongation ~ 663 858
Tensile Modulus
100% Kg/cm 25 18
200% Kg/cm2 41 24
300% Kg/cm 61 30
The "Tropical Humidity Conditions" were 38C and 90%
relative humidity.
; RD/127/A-02-A-25
. ~
