Title of Invention

"SILICA-FILLED ELASTOMERIC COMPOUNDS"

Abstract A filled halobutyl elastomer composition comprising at least one halobutyl elastomer, in the range of from 20 parts to 250 parts by weight per hundred parts of elastomer (phr) of at least one mineral filler and in the range of from 0.5 to 10 phr of at least one protected thiol modifier comprising a blocked mercaptosilane.
Full Text Silica-Filled elastomeric compounds
Field of the Invention
The present invention relates to silica-filled halogenated butyl
elastomers, in particular bromobutyl elastomers (BUR).
Background of the invention:
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 filler,
in particular carbon black and highly unsaturated elastomers such as
polybutadiene (BR) and styrene butadiene copolymers (SBR) occurs
because of the large number of carbon-carbon double bonds present in
these copolymers. Butyl elastomers are known to interact poorly with
fillers like carbon black. For example, a compound prepared by mixing
carbon black 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.
WO-99/09036-A1 discloses protected thiol modifiers in general and
also their use in silica filled compound comprising organic polymers.
However, this reference is silent about the beneficial use of protected thiol
modifiers in compounds comprising halogenated butyl rubbers. Butyl
elastomers may have only one tenth, or fewer, of the carbon-carbon
double bonds found in BR or SBR as disclosed in WO-99/09036-A1.
Thus, our findings that the use of protected thiol modifiers in fact results in
compounds with a very good balance of physical properties while still
maintaining acceptable levels of processability is surprising.
Summary of the Invention:
The present invention provides a composition comprising at least
one halobutyl elastomer, at least one mineral filler and at least one
protected thiol modifier.
It has been discovered that protected thiol modifiers enhance the
interaction of halobutyl elastomers with mineral fillers, resulting in
improved compound properties such as tensile strength and abrasion
resistance (DIN). This is surprising as the non-halogenated butyl
elastomer does not respond in the same way.
Accordingly, in another aspect the present invention provides a
process which comprises mixing a halobutyl elastomer with at least one
mineral filler, in the presence of at least one protected thiol modifier, and
curing the resulting filled halobutyl elastomer.
The halobutyl elastomer that is admixed with one protected thiol
modifier may be a mixture with another elastomer or elastomeric
compound. The halobutyl elastomer should constitute more than 5% of
any such mixture. 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 polychloroprene
or an elastomer compound containing one or more of these
elastomers.
The filled halobutyl elastomer can be cured in the presence of at
least one cross-linking agent to obtain a product which has improved
properties, for instance in abrasion resistance, rolling resistance and
traction. Curing can be effected with sulfur but does not have to be. The
preferred amount of sulfur is in the range of from 0 to 2.0 parts by weight
per hundred parts of rubber. An activator, for example zinc oxide, may
also be used, in an amount in the range of from 0.5 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 the known manner. See, for instance, chapter 2,
"The Compounding and Vulcanization of Rubber", of "Rubber
Technology", 3rd edition, published by Chapman & Hall, 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 halobutyl elastomers,
for example, such as bis dieneophiles (for example m-phenyl-bismaleimide,
HVA2), phenolic resins, amines, amino-acids, peroxides, zinc
oxide and the like. Combinations of the aforementioned curatives may
also be used.
The mineral-filled halobutyl elastomer of the invention can be
admixed with other elastomers or elastomeric compounds before it is
subjected to curing.
Detailed Description of the Invention
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.
Thus, halobutyl 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 C$ to CQ
conjugated diolefin, preferably isoprene - (brominated isobuteneisoprene-
copolymers BUR)). Co-monomers other than conjugated
diolefins can be used, however, and mention is made of alkyl-substituted
\tmy\ aromatic co-monomers such as Ci-C4-alkyl substituted styrene. An
example of such an elastomer which is commercially available is
brominated isobutylene methylstyrene copolymer (BIMS) in which the comonomer
is p-methylstyrene.
Brominated butyl elastomers typically comprise in the range of from
0.1 to 10 weight percent of repeating units derived from isoprene and in
the range of from 90 to 99.9 weight percent of repeating units derived
from isobutylene (based upon the hydrocarbon content of the polymer)
and in the range of from 0.1 to 9 weight percent bromine (based upon the
bromobutyl polymer). A typical bromobutyl polymer has a molecular
weight, expressed as the Mooney viscosity according to DIN 53 523 (ML
1 + 8 at 125°C), in the range of from 25 to 60.
For use in the present invention the brominated butyl elastomer
preferably contains in the range of from 0.5 to 5 weight percent of
repeating units derived from isoprene and in the range of from 95 to 99.5
weight percent of repeating units derived from isobutylene (based upon
the hydrocarbon content of the polymer) and in the range of from 0.2 to 3
weight percent, preferably from 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 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 (phr).
Examples of suitable brominated butyl elastomers include Bayer
Bromobutyl® 2030, Bayer Bromobutyl® 2040 (BB2040), and Bayer
Bromobutyl® X2 commercially available from Bayer. Bayer BB2040 has a
Mooney viscosity (ML 1+8 @ 125°C) of 39 ± 4, a bromine content of 2.0 ±
0.3 wt% and an approximate molecular weight of 500,000 grams per
mole.
The brominated butyl elastomer used in this invention 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 brominated butyl rubber with a solid
polymer based on a conjugated diolefin monomer which also includes
some C-S-(S)n-C bonds, where n is an integer from 1 to 7, the mixing
being carried out at a temperature greater than 50 °C and for a time
sufficient 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 copolymer generally have
the structural formula:
wherein R is a hydrogen atom or an alkyl group containing from 1
to 8 carbon atoms and wherein R-| and R-| 1 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 nonlimiting
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 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.
The polymer based on a conjugated diene monomer can be a
homopolyrner, 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
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 in the range of from
8 to 20 carbon atoms, preferably from 8 to 14 carbon atoms. Some
examples of vinyl aromatic monomers which can be so copolymerized
include styrene, alpha-methyl styrene, various alkyl styrenes including pmethylstyrene,
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.
The halogenated butyl elastomer may be used alone or in
combination with other elastomers such as:
BR - polybutadiene
ABR - butadiene/Ci-C4 alkyl acrylate copolymers
CR - polychloroprene
IR - polyisoprene
SBR - styrene/butadiene copolymers with styrene contents
of 1 to 60, preferably 20 to 50 wt.%
IIR - isobutylene/isoprene copolymers
NBR - butadiene/acrylonitrile copolymers with acrylonitrile
contents of 5 to 60, preferably 10 to 40 wt.%
HNBR - partially hydrogenated or completely hydrogenated
NBR
EPDM - ethylene/propylene/diene copolymers
The filler is composed of particles of a mineral, and examples
include silica, silicates, clay (such as bentonite), gypsum, alumina,
titanium dioxide, talc and the like, as well as mixtures thereof.
Further examples are:
- highly disperse silicas, prepared e.g. by the precipitation of
silicate solutions or the flame hydrolysis of silicon halides, with
specific surface areas of 5 to 1000, preferably 20 to 400 m2/g
(BET specific surface area), and with primary particle sizes of
10 to 400 nm; the silicas can optionally also be present as
mixed oxides with other metal oxides such as those of Al, Mg,
Ca, Ba, Zn, Zrand Ti;
- synthetic silicates, such as aluminum silicate and alkaline
earth metal silicate like
- magnesium silicate or calcium silicate, with BET specific
surface areas of 20 to 400 m2/g and primary particle
diameters of 10 to 400 nm;
- natural silicates, such as kaolin and other naturally occurring
silica;
- glass fibres and glass fibre products (matting, extrudates) or
glass microspheres;
- metal oxides, such as zinc oxide, calcium oxide, magnesium
oxide and aluminium oxide;
- metal carbonates, such as magnesium carbonate, calcium
carbonate and zinc carbonate;
- metal hydroxides, e.g. aluminium hydroxide and magnesium
hydroxide;
or combinations thereof.
These mineral particles have hydroxyl groups on their surface,
rendering them hydrophilic and oleophobic. This exacerbates the
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 in the range of from
1 to 100 microns, preferably between 10 and 50 microns and most
preferably between 10 and 25 microns. It is preferred that less than 10
percent by volume 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 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 787/11, of from 0 to 10 percent by
weight. Suitable silica fillers are available under the trademarks HiSil®
210, HiSil® 233 and HiSil® 243 from PPG Industries Inc. Also suitable
are Vulkasil® S and Vulkasil® N, from Bayer AG.
Those mineral filler can may be used in combination with known
non-mineral fillers, such as
- carbon blacks; the carbon blacks to be used here are
prepared by the lamp black, furnace black or gas black
process and have BET specific surface areas of 20 to 200
m2/g, e.g. SAP, ISAF, HAF, FEF or GPF carbon blacks;
or
- rubber gels, especially those based on polybutadiene,
butadiene/styrene copolymers, butadiene/acrylonitrile
copolymers and polychloroprene.
Non-mineral fillers are not normally used as filler in the halobutyl
elastomer compositions of the invention, but in some embodiments they
may be present in an amount up to 40 phr. It is preferred that the mineral
filler should constitute at least 55% by weight of the total amount of filler.
If the halobutyl elastomer composition of the invention is blended with
another elastomeric composition, that other composition may contain
mineral and/or non-mineral fillers.
The protected thiol modifier preferably comprises at least one
silicon and one sulfur atom. Examples of suitable protected thiol
modifiers are disclosed in WO-99/09036-A1 which hereby is incorporated
by reference with regards to jurisdictions allowing for this feature.
Preferred are blocked mercaptosilanes selected from the group
consisting of
[[(ROC(=0))p-(G)j]k-Y-S]r-G-(SiX3)s (1); and
[{X3Si)q-G]a-[Y-[S-G-SiX3Jb]c (2)
wherein
Y is a polyvalent species (Q)ZA(=E) selected from the group
consisting of
-C(=NR)-; -SC(=NR)-; -SC(=O)-; -OC(=O)-; -S(=O)-; -S(=O)2-;
-OS(=0)2-;
-(NR)S(=0)2-; -SS(=0)-; -OS(=0)-; -(NR)S(=O)-; -SS(=O)2-;
(-S)2P(=0)-;
-(-S)P(=0)-; -P(=0)(-)2; (-S)2P(=S)-; -(-S)P(=S)-; -P(=S)(-)2;
(-NR)2P(=0)-;
(-NR)(-S)P(=0)-; (-0)(-NR)P(=0)-; (-O)(-S)P(=O)-; (-O)2P(=O)-;
-(-0)P(=0)-; -(-NR)P(=0)-; (-NR)2P(=S)-; (-NR)(-S)P(=S)-;
(-0){-NR)P(=S)-; (_0)(-S)P(=S)-; (-O),P(=S)-; -(-O)P(=S)-; and
-(-NR)P(=S)-;
each wherein the atom (A) attached to the unsaturated heteroatom
(E) is attached to the sulfur, which in turn is linked via a group G to the
silicon atom;
each R is chosen independently from hydrogen, straight, cyclic or
branched alky! that may or may not contain unsaturation, alkenyl groups,
aryl groups, and aralkyl groups, with each R containing from 1 to 18
carbon atoms;
each G is independently a monovalent or polyvalent group derived
by substitution of alkyl, alkenyl, aryl or aralkyl wherein G can contain from
1 to 18 carbon atoms, with the proviso that G is not such that the silane
would contain an alpha.beta-unsaturated carbonyl including a carboncarbon
double bond next to the thiocarbonyl group, and if G is univalent,
G can be a hydrogen atom;
X is independently a group selected from the group consisting of -
Cl, -Br, RO-, RC(=O)0-, R2C=NO-, R2NO- or R3N-, -R3 -(OSiR3)t(OsiR3)
wherein each R and G is as above and at least one X is not -R;
p is 0 to 5; r is 1 to 3; z is 0 to 2; q is 0 to 6; a is 0 to 7; b is 1 to 3; j
is 0 to 1, but it may be 0 only if p is 1, c is 1 to 6, t is 0 to 5; s is 1 to 3; k is
1 to 2, with the provisos that
(A) if A is carbon, sulfur or sulfonyl, then (i) a + b = 2 and (ii) k = 1;
(B) if A is phosphorus, then a+b=3 unless both
(i) c 1 and (ii) b= 1, in which case a = c+1; and
(C) if A is phosphorus, then k is 2.
Specific examples of protected thiol modifier comprise thioacetic
acid S-trimethoxysilyl-methyl ester, thioacetic acid S-triethoxysilyl-methyl
ester, thioacetic acid S-(2-trimethoxylsilyl-ethyl) ester, thioacetic acid S-(2-
triethoxysilyl-ethyl) ester, thioacetic acid S-(3-trimethoxysilyl-propyl) ester,
thioacetic acid S-(3-triethoxysilyl-propyl) ester, thiopropionic acid Strimethoxylsilyl-
methyl ester, thiopropionic acid S-triethoxylsilyl-methyl
ester, thiopropionic acid S-(2-trimethoxylsilyl-ethyl) ester, thiopropionic
acid S-(2-triethoxylsilyl-ethyl) ester, thiopropionic acid S-(3-
trimethoxylsilyl-propyl) ester, thiopropionic acid S-(3-triethoxylsilyl-propyl)
ester, thiobutyric acid S-trimethoxysilyl-methyl ester, thiobutyric acid Striethoxysilyl-
methyl ester, thiobutyric acid S-(2-trimethoxysilyl-ethyl) ester,
thiobutyric acid S-(2-triethoxysilyl-ethyl) ester, thiobutyric acid S-(3-
trimethoxysilyl-propyl) ester, thiobutyric acid S-(3-triethoxysilyl-propyl)
ester, pentanethioic acid S-trimethoxysilyl-methyl ester, pentanethioic acid
S-triethoxysilyl-methyl ester, pentanethioic acid S-(2-trimethoxysilyl-ethyl)
ester, pentanethioic acid S-(2-triethoxysilyl-ethyl) ester, pentanethioic acid
S-(3-trimethoxysilyl-propyl) ester, and pentanethioic acid S-(3-
triethoxysilyl-propyl) ester. Preferred are pentanethioic acid S-(3-
trimethoxysilyl-propyl) ester, and pentanethioic acid S-(3-triethoxysilylpropyl)
ester.
Preferably, the inventive compound comprises in the range of from
0.5 to 10 phr of one or more protected thiol modifiers, more preferably in
the range of from 1 to 5 phr.
It may be advantageous to add one or more silazane compounds
to the inventive compound. These siliazane compound(s) can have one
or more silazane groups, e.g. disilazanes. Organic silazane compounds
are preferred. Examples include but are not limited to
hexamethyldisilazane, heptamethyldisilazane, 1,1,3,3-tetramethyldisilazane,
1,3-bis(chloromethyl)tetramethyldisilazane, 1,3-divinyl-1,1,3,3-
tetramethyldisilazane, and 1,3-diphenyltetramethyldisilazane.
It may further be advantageous to further add additives which give
enhanced physical properties to the inventive compound such as
hydroxyl- and amine-containing additives. Examples of hydroxyl- and
amine-containing additives include proteins, aspartic acid, 6-aminocaproic
acid, diethanolamine and triethanolamine. Preferably, the hydroxyl- and
amine-containing additive should contain a primary alcohol group and an
amine group separated by methylene bridges, which may be branched.
Such compounds have the general formula HO-A-NH2; wherein A
represents a Ci to C2o alkylene group, which may be linear or branched.
More preferably, the number of methylene groups between the two
functional groups should be in the range of from 1 to 4. Examples of
preferred additives include monoethanolamine and N,Ndimethylaminoalcohol.
The amount of filler to be incorporated into the inventive halobutyl
rubber/elastomer compound can vary between wide limits. Typical
amounts of filler range from 20 parts to 250 parts by weight, preferably
from 30 parts to 100 parts, more preferably from 40 to 80 parts per
hundred parts of elastomer. The amount of the silazane compound is
preferably in the range of from 0.5 to 10 parts per hundred parts of
elastomer, preferably of from 1 to 6, more preferably of from 2 to 5 parts
per hundred parts of elastomer. The amount of hydroxyl- and aminecontaining
additive used in conjunction with the silazane compound is
typically in the range of from 0.5 to 10 parts per hundred parts of
elastomer, preferably of from 1 to 3 parts per hundred parts of elastomer.
Furthermore 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 halobutyl rubber(s)/elastomer(s), filler(s), protected thiol
modifier(s) and optional further additive(s) 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.
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 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.
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, 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.
In a preferred embodiment of the invention, bromobutyl elastomer,
silica particles, protected thiol modifier(s) and, optionally, further additives
and/or, optionally, processing oil extender are mixed on a two-roll mill at a
nominal mill 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 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 four ingredients at a temperature not exceeding
150 °C is a compound which has good stress/strain properties and which
can be readily processed further on a warm mill with the addition of
curatives.
The filled halobutyl rubber compositions of the invention, and in
particular filled bromobutyl rubber compositions, find many uses, but
mention is made particularly of use in tire tread compositions. Important
features 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 these desirable properties. Thus, an indicator of traction is tan 8
at 0°C, with a high tan 8 at 0 °C correlating with good traction. An
indicator of rolling resistance is tan 8 at 60 °C, with a low tan 8 at 60 °C
correlating with low rolling resistance. Rolling resistance is a measure of
the resistance to forward movement of the tire, and low rolling resistance
is desired to reduce fuel consumption. Low values of loss modulus at 60
°C are also indicators of low rolling resistance. As is demonstrated in the
examples below, compositions of the invention display high tan 8 at 0°C,
low tan 8 at 60°C and low loss modulus at 60°C.
The invention is further illustrated in the following examples.
Examples
Description of tests:
Abrasion Resistance:
DIN 53-516 (60 grit Emery paper)
Physical Testing:
Stress-Strain measurements were determined at 23 °C on an
Instron 4501 according to ASTM 412 Method A. Samples for Stress-
Strain measurements were cut from a 2 mm macro sheet, cured for
tc90+5 minutes, using Die C. Hardness values were determined with the
use of a Shore A2 Tester according to ASTM 2240.
Dynamic Property Testing:
Dynamic testing (tan 6 at 0 °C and 60 °C, Loss modulus at 60 °C)
were carried out using the GABO. The GABO is a dynamic mechanical
analyzer for characterizing the properties of vulcanized elastomeric
materials. The dynamic mechanical properties give a measure of traction
with the best traction usually obtained with high values of tan 5 at 0 °C.
Low values of tan 5 at 60°C, and in particular, low loss moduli at 60 °C are
indicators of low rolling resistance.
Cure rheometry:
ASTM D 52-89 MDR2000E Rheometer at 1° arc and 1.7 Hz
Description of Ingredients:
BB2030 - Bayer® Bromobutyl™ 2030 - available from Bayer Inc.
RB301 - Bayer® Butyl™ 301 - non-halogenated Butyl available
from Bayer Inc.
Hi-Sil® 233 - silica - a product of PPG
NXT Silane - Pentanethioic acid S-(3-triethoxysilyl-propyl) ester a
product of OSI
Maglite® D - magnesium oxide a product of CP Hall
HVA #2 - m-phenyl-bis-maleimide - available from Dupont Canada
Inc.
Stearic acid - available from H.M. Royal.
Sulfur NBS - available from Akron Rubber Development Laboratory
Inc.
Zinc oxide - available from St. Lawrence Chem. Co. Ltd.
Examples 1-7
The effect of incorporation of protected thiol modifier(s) into
halogenated butyl elastomer/silica compounds was investigated via the
formulation of several compounds of which NXT Silane was incorporated
as the protected thiol modifier. For comparison, a halogenated butyl
elastomer/silica compound (Example 1) with no silane and several nonhalogenated
butyl elastomer/silica compounds (Examples 3, 5 and 7)
were also prepared as control compounds. The amount of ingredients
used is shown in Table 1.
Examples 1-7 were prepared with the use of two roll, 6x12 inch
Mill operating with a roll temperature of 30 °C. The compounds were
prepared according to the following mixing sequence:
t = 0min: Add1A+1B*
t = 2min: Add 1C*
t = 3 min : Sweep
t = 4 min : Sweep
t = 5 min : Dump
* as indicated in Table 1 in column "step"
Each of these compounds was then heat treated (banding with a
tight nip setting) on a two roll, 6 x 12 in Mill operating with a roll
temperature of 100 °C for a total of 10 minutes. Following the heat
treatment, the curatives (2A) were added to the room temperature
compounds with the use of a two roll 6 x 12 in Mill operating with a roll
temperature of 30 °C. The compounds were refined with six endwise
passess.
(Table Removed)
Note: TSTT = To Soft To Test. Compounds denoted as TSTT were
deemed too soft to be tested by DIN 53-516. DNB = Did Not
Break. Compounds denoted as DNB possessed ultimate
elongations which exceeded the upper limit of the Instron 4501,
operating according to ASTM 412 Method A.
As can be seen from the data presented in Table 2, the physical
properties of the compounds based on halogenated butyl (BB2030) are
significantly superior to those measured for compounds based on non-
halogenated butyl (RB301). Regardless of which curative package was
employed, the enhanced reactivity of compounds based on halogenated
butyl (BB2030) compared to compounds based on non-halogenated butyl
(RB301) allowed for the attainment of excellent physical properties in the
final compound. Specifically, compounds which were based on RB301
(Examples 3, 5 and 7) possessed signifcantyl poorer abrasion resistance
(in fact these compounds were too soft to be tested) indexes compared to
their BB2030 analogues (Examples 2, 4 and 6). The significantly lower
values of the modulus at 300 % elongation for Examples 3, 5 and 7 c.f.
Examples 2, 4 and 6 is yet a further indication of the poor degree of filler
interaction (and thus physical reinforcement) present in these
formulations.





WE CLAIM:
1. A filled halobutyl elastomer composition comprising at least one halobutyl elastomer, in the range of from 20 parts to 250 parts by weight per hundred parts of elastomer (phr) of at least one mineral filler and in the range of from 0.5 to 10 phr of at least one protected thiol modifier comprising a blocked mercaptosilane.
2. The filled halobutyl elastomer composition as claimed in claim 1, wherein the halobutyl elastomer is a Bromobutyl elastomer comprising in the range of from 0.1 to 9 weight percent bromine.
3. The filled halobutyl elastomer composition as claimed in claim 1 or 2, wherein the mineral filler is silica.
4. The filled halobutyl elastomer composition as claimed in any one of claims 1 to 3, wherein the blocked mercaptosilane is selected from the group consisting of:
(Formula Removed)
wherein,
Y is a polyvalent species (Q)ZA(=E) selected from the group consisting of
i. -C(=NR)-; -SC(=NR)-; -SC(=O)-; -OC(=O)-; -S(=O)-; -S(=O)2-;
ii. -OS(=O)2-;
iii. -(NR)S(=O)2-; -SS(=O)-; -OS(=O)-; -(NR)S(=O)-; -SS(=O)2-; iv. (-S)2P(=O)-;
v. -(-S)P(=O)-; -P(=O)(-)2; (-S)2P(=S)-; -(-S)P(=S)-; -P(=S)(-)2; vi. (-NR)2P(=O)-;
vii. (-NR)(-S)P(=O)-; (-O)(-NR)P(=O)-; (-O)(-S)P(=O)-; (-O)2P(=O)-; viii. -(-O)P(=O)-; -(-NR)P(=O)-; (-NR)2P(=S)-; (-NR)(-S)P(=S)-; ix. (-O)(-NR)P(=S)-; (-O)(-S)P(=S)-; (-O),P(=S)-; -(-O)P(=S)s and
x. -(-NR)P(=S)-;
each wherein the atom (A) attached to the unsaturated heteroatom (E) is attached to the sulfur, which in turn is linked via a group G to the silicon atom;
each R is chosen independently from hydrogen, straight, cyclic or branched alkyl that may or may not contain unsaturation, alkenyl groups, aryl groups, and aralkyl groups, with each R containing from 1 to 18 carbon atoms;
each G is independently a monovalent or polyvalent group derived by substitution of alkyl, alkenyl, aryl or aralkyl wherein G can contain from 1 to 18 carbon atoms, with the proviso that G is not such that the silane would contain an alpha,beta-unsaturated carbonyl including a carbon-carbon double bond next to the thiocarbonyl group, and if G is univalent, G can be a hydrogen atom;
X is independently a group selected from the group consisting of-C1, -Br, RO-, RC(=O)O-, R2C=NO-, R2NO- or R3N-, -R3 -(OSiR3)t(OsiR3) wherein each R and G is as above and at least one X is not -R;
p is 0 to 5; r is 1 to 3; z is 0 to 2; q is 0 to 6; a is 0 to 7; b is 1 to 3; j is 0 to 1, but it may be 0 only if p is 1, c is 1 to 6, t is 0 to 5; s is 1 to 3; k is 1 to 2, with the provisos that
(A) if A is carbon, sulfur or sulfonyl, then (i) a + b = 2 and (ii) k = 1;
(B) if A is phosphorus, then a+b=3 unless both (i) c > 1 and (ii) b= 1, in which case a = c+1; and
(C) if A is phosphorus, then k is 2.
5. The filled halobutyl elastomer composition as claimed in any one of claims 1 to 4, wherein the protected thiol modifier comprises thioacetic acid S-trimethoxysilyl-methyl ester, thioacetic acid S-triethoxysilyl-methyl ester, thioacetic acid 5'-(2-trimethoxylsilyl-ethyl) ester, thioacetic acid S'-(2-triethoxysilyl-ethyl) ester, thioacetic acid S-(3-trimethoxysilyl-propyl) ester, thioacetic acid S-(3-triethoxysilyl-propyl) ester, thiopropionic acid S-trimethoxylsilyl-methyl ester, thiopropionic acid S-triethoxylsilyl-methyl ester, thiopropionic acid S-(2-trimethoxylsilyl-ethyl) ester, thiopropionic acid S-(2-triethoxylsilyl-ethyl) ester, thiopropionic acid S-(3-trimethoxylsilyl-propyl) ester, thiopropionic acid
S'-(3-triethoxylsilyl-propyl) ester, thiobutyric acid iS-trimethoxysilyl-methyl ester, thiobutyric acid S-triethoxysilyl-methyl ester, thiobutyric acid S-(2-trimethoxysilyl-ethyl) ester, thiobutyric acid 5'-(2-triethoxysilyl-ethyl) ester, thiobutyric acid S-(3-trimethoxysilyl-propyl) ester, thiobutyric acid iS'-(3-triethoxysilyl-propyl) ester, pentanethioic acid S-trimethoxysilyl-methyl ester, pentanethioic acid S-triethoxysilyl-methyl ester, pentanethioic acid 5-(2-trimethoxysilyl-ethyl) ester, pentanethioic acid S-(2-triethoxysilyl-ethyl) ester, pentanethioic acid S-(3-trimethoxysilyl-propyl) ester, and pentanethioic acid S-(3-triethoxysilyl-propyl) ester or mixtures thereof.
6. A process for preparing a filled halobutyl elastomer which comprises:
admixing at a temperature in the range of from 25 to 200 °C at least one
halobutyl elastomer, in the range of from 20 parts to 250 parts by weight
per hundred parts of elastomer (phr) of at least one mineral filler, in the
range of from 0.5 to 10 phr of at least one protected thiol modifier
comprising a blocked mercaptosilane and in the range of from 0.5 to 3 phr
of at least one cross-linking agent; and, curing the resulting filled
halobutyl elastomer.
7. The filled halobutyl elastomer composition as claimed in claims 1 to 5, as and when used in improving rolling resistance, wet traction, and/or abrasion resistance of a tire tread composition.

Documents:

1765-DELNP-2006-Abstract-(14-11-2011).pdf

1765-delnp-2006-abstract.pdf

1765-DELNP-2006-Claims-(14-11-2011).pdf

1765-delnp-2006-claims.pdf

1765-DELNP-2006-Correspondence Others-(14-11-2011).pdf

1765-delnp-2006-Correspondence-Others-(19-05-2011).pdf

1765-delnp-2006-correspondence-others-1.pdf

1765-delnp-2006-correspondence-others.pdf

1765-delnp-2006-description (complete).pdf

1765-delnp-2006-form-1.pdf

1765-delnp-2006-form-18.pdf

1765-delnp-2006-form-2.pdf

1765-delnp-2006-Form-3-(19-05-2011).pdf

1765-delnp-2006-form-3.pdf

1765-delnp-2006-form-5.pdf

1765-DELNP-2006-GPA-(14-11-2011).pdf

1765-delnp-2006-gpa.pdf

1765-delnp-2006-pct-210.pdf

1765-delnp-2006-pct-304.pdf

1765-delnp-2006-Petition-137-(19-05-2011).pdf


Patent Number 250409
Indian Patent Application Number 1765/DELNP/2006
PG Journal Number 01/2012
Publication Date 06-Jan-2012
Grant Date 03-Jan-2012
Date of Filing 31-Mar-2006
Name of Patentee LANXESS INC.
Applicant Address P.O. BOX 3001, 1265 VIDAL STREET SOUTH, SARNIA, ONTARIO N7T 7M2, CANADA.
Inventors:
# Inventor's Name Inventor's Address
1 WILFRIED BRAUBACH STEINBERG 7, 42659 SOLINGEN, GERMANY.
2 RUI RESENDES 58 LOCHLOMOND PLACE, SARNIA, ONTARIO N7S 4H7, CANADA.
PCT International Classification Number C08L 23/28
PCT International Application Number PCT/CA2004/001850
PCT International Filing date 2004-10-21
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2,446,474 2003-10-24 Canada