JP3037119B2 - Rubber alloy composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanizable rubber alloy composition, and more particularly, to oil resistance and heat resistance obtained by alloying a pre-vulcanized fluororubber and / or a compound thereof with an acrylic rubber. The present invention relates to a rubber alloy composition having excellent heat resistance, cold resistance and compression set resistance.

[0002]

2. Description of the Related Art At present, fluororubber is a rubber material having the best oil resistance and heat resistance, but has a problem that it is inferior in cold resistance and very expensive. ing.

Acrylic rubber is important as a heat-resistant and oil-resistant rubber material because of its excellent balance of heat resistance, oil resistance and price. However, acrylic rubber is
Since the heat resistance and oil resistance are inferior to fluororubber, its application is limited depending on the use site.

In recent industrial applications, particularly in the field of automobiles, the heat resistance and oil resistance of acrylic rubber are insufficient, and a rubber material having an intermediate performance with that of fluoro rubber is required. That is, a rubber material which has intermediate heat resistance between acrylic rubber and fluororubber and excellent oil resistance close to that of fluororubber and is less expensive than fluororubber is desired.

On the other hand, attempts have been made to knead and blend acrylic rubber and fluorine rubber. However, kneading is difficult in processing, or the affinity of fluororubber to acrylic rubber is poor, so both components are difficult to disperse sufficiently uniformly, and phase separation occurs during heat treatment for vulcanization, Further, the degree of dispersion was reduced. Therefore, physical properties, particularly heat resistance and compression set resistance, are not practically satisfactory, and a significant cost reduction has not been achieved.

Further, in order to improve heat resistance, a method of copolymerizing an acrylate monomer and a fluorine monomer (for example, JP-A-7-25972), dissolving a fluorine-containing polymer in the acrylic monomer Or swell,
Then, the monomer is subjected to polymerization to increase the molecular weight (for example, JP-A-4-363352, JP-A-5-9).
No. 8116) has been attempted, but the heat resistance and compression set resistance of the vulcanized compound have not been satisfactory and have become expensive materials.

The present invention has been made in view of these points, and has excellent oil resistance close to fluororubber, heat resistance intermediate between fluororubber and acrylic rubber, and cold resistance superior to fluororubber. It is an object of the present invention to provide a rubber alloy composition that can be manufactured at a lower cost than a fluororubber and at a lower cost than an acrylic rubber depending on the method.

[0008]

Means for Solving the Problems and Embodiments of the Invention
The present inventors have conducted intensive studies in order to solve the above problems, and as a result, a vulcanizable rubber alloy composition containing a pre-vulcanized fluororubber and / or a compound thereof is close to a fluororubber. It has excellent oil resistance, heat resistance between fluorine rubber and acrylic rubber, and cold resistance better than fluoro rubber, and also has excellent compression set resistance and is less expensive than fluoro rubber. And found that it could be provided at low cost, and completed the present invention.

[0009] That is, the rubber alloy composition of the present invention is characterized in that vulcanizable vulcanizate is formed by including a vulcanized fluororubber and / or a compound thereof in an acrylic rubber.

More specifically, the vulcanizable rubber alloy composition of the present invention comprises a pre-vulcanized fluororubber and / or a compound thereof dispersed uniformly in an acrylic rubber. Because the phase separation during the heat treatment is prevented, and the vulcanization of the acrylic rubber itself, it is considered that the fluororubber and the acrylic rubber are co-crosslinked inside the phase around the interface of the fluororubber phase, The vulcanizate of the rubber alloy composition of the present invention has the excellent physical properties described above,
It has the characteristic of having chemical properties.

[0011] Furthermore, the compound of the pre-vulcanized fluororubber includes so-called industrial materials such as vulcanized burrs generated by compression molding and vulcanized offcuts generated by injection molding, transfer molding and extrusion molding. Since waste can also be used, it is characterized in that resources are reused and can be provided as extremely inexpensive materials.

In the present invention, as the pre-vulcanized fluororubber and / or the compound thereof, those obtained by vulcanizing the fluororubber alone or the compound thereof with a vulcanizing agent can be used. There is no particular limitation on the type and amount of the vulcanizing agent for vulcanization, and any vulcanizing agent may be used as long as it can vulcanize the fluororubber and / or a compound thereof. As the vulcanizing agent, a polyol vulcanizing system, an amine vulcanizing system, a peroxide vulcanizing system, an ion vulcanizing system or the like generally used for vulcanizing a fluororubber can be used.

[0013] Fluororubber is generally molded by primary vulcanization and then secondary vulcanized to complete vulcanization. The pre-vulcanized fluororubber and / or its blend in the present invention may be those after primary vulcanization or those after secondary vulcanization, but those after primary vulcanization are preferred. There is no particular limitation on the compound, and if necessary, a reinforcing filler, a bulking filler, a vulcanization stabilizer, an acid acceptor, a processing aid, a coupling agent, a plasticizer, a pigment, etc. Good. However, physical properties of fluorine rubber and acrylic rubber,
In particular, it is not preferable to add a compound that adversely affects heat resistance.

It is particularly desirable to use burrs or offcuts generated when a rubber product is molded and processed by primary vulcanization from the viewpoint of resource recycling and cost reduction.

In the present invention, the primary vulcanization conditions of the pre-vulcanized fluororubber and / or the compound thereof are 10
0 to 300 ° C for several seconds to 48 hours, preferably 100 to
The temperature may be within a range of one hour at 250 ° C. The secondary vulcanization conditions may range from 30 to 48 hours at 100 to 300 ° C, preferably from 24 to 48 hours at 150 to 250 ° C. This is because if the vulcanization time is too short, the degree of cross-linking becomes insufficient, and if it is more than 48 hours, it is not economical, and the fluororubber deteriorates depending on the temperature conditions.

The mixing ratio of the pre-vulcanized fluoro rubber and the acrylic rubber is not particularly limited, but is preferably 10 to 500 parts by weight per 100 parts by weight of the acrylic rubber in view of the properties of the vulcanized rubber alloy composition. Range. When the amount of the fluoro rubber is 10 parts by weight or less, the effect of improving oil resistance and heat resistance is small, and when the amount is 500 parts by weight or more,
Processing is difficult or physical properties such as tensile strength are reduced, and practical limitations are imposed.

The form of mixing the pre-vulcanized fluororubber and / or its blend with the acrylic rubber is as follows:
There is no particular limitation. However, for smooth mixing and uniformity with the acrylic rubber, it is more desirable that the compound powder has an average particle diameter of 5 mm or less.

The fluororubber in the present invention is a copolymer of a fluorine-containing monomer having 2 to 8 carbon atoms, specifically, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, tetrafluoroethylene, Chlorofluoroethylene and at least one compound selected from the group consisting of perfluoro (alkyl vinyl ether) having 1 to 5 carbon atoms in the alkyl group as essential components, and at least one of tetrafluoroethylene and vinylidene fluoride It is a copolymer with another olefin copolymerizable therewith, and may be obtained by copolymerizing an active halogen group-containing monomer or an epoxy group-containing monomer which serves as a crosslinking point, if necessary.

Of these pre-vulcanized fluororubbers, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene-per A fluoro (methyl vinyl ether) copolymer, a tetrafluoroethylene-propylene copolymer, and a tetrafluoroethylene-vinylidene fluoride-propylene copolymer are particularly preferable, and generally commercially available fluororubber can be used. The fluorine rubber preferably has a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 150.

The acrylic rubber used in the present invention is an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and an alkoxyalkyl having an alkoxy group having 1 to 4 carbon atoms and an alkylene group having 1 to 4 carbon atoms. At least one acrylate ester selected from acrylates, and an active halogen group-containing monomer, an epoxy group-containing monomer, a carboxyl group-containing monomer, a diene compound, a dihydrodicyclopentadienyl group-containing (as a crosslinking point) It is a copolymer with at least one monomer selected from the group of (meth) acrylates. Other copolymerizable monomers that can be copolymerized with the above-mentioned monomer in this copolymer,
For example, a copolymer of acrylonitrile, vinyl acetate, and the like may be used. A commercially available acrylic rubber can also be used.

Specific examples of these acrylates include methyl acrylate, ethyl acrylate, n-
Examples thereof include butyl acrylate, 2-ethylhexyl acrylate, methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, and butoxyethyl acrylate.

Specific examples of the monomer copolymerized as the crosslinking point include monomers containing an active halogen group such as vinyl chloroacetate, 2-chloroethyl vinyl ether, and 2-chloroethyl acrylate; glycidyl methacrylate; Epoxy group-containing monomers such as glycidyl acrylate and allyl glycidyl ether; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, monomethyl maleate and monomethyl itaconate; diene compounds such as ethylidene norbornene and dicyclopentadiene; Examples thereof include dihydrodicyclopentadienyl group-containing (meth) acrylates such as dicyclopentadienyl acrylate and dicyclopentadienyl methacrylate.

The molecular weight of these acrylic rubbers must be at least as large as the acrylic rubber itself can self-vulcanize. On the other hand, an extremely high molecular weight may impair the compatibility with a pre-vulcanized fluororubber and / or a compound thereof, so that the number average molecular weight is 3,000 to 50.
0000 is desirable. More preferably, one having a Mooney viscosity (ML1 + 4, 100 ° C.) of 10 to 150 is used.

For the production of these acrylic rubbers, conventionally known various polymerization methods for polymerizing a predetermined amount of a monomer by bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization or the like can be employed.

For the alloying of the present invention, a vulcanizing agent generally used for vulcanizing acrylic rubber can be used, but a vulcanizing agent capable of co-vulcanizing acrylic rubber and fluororubber can be used. By using it, more preferable physical properties can be obtained. For example, when the crosslinking point monomer of the acrylic rubber is an active halogen group-containing monomer or a carboxyl group-containing monomer and the fluororubber is a polyol vulcanized type, a polyamine type, a triazine type compound or a triazine type compound is used. When a combination system with an organic onium compound and or a dithiocarbamate is preferable as a vulcanizing agent, and when the fluorine rubber is an amine vulcanizing system with an epoxy group-containing monomer,
Diamine-based vulcanizing agents are preferred. Further, when the diene compound or the dihydrodicyclopentadienyl group-containing (meth) acrylic acid ester is a peroxide vulcanized rubber, an organic peroxide is preferable as the vulcanizing agent.

The method for preparing the rubber alloy composition of the present invention is not particularly limited, and the above-mentioned various components are uniformly mixed by a usual rubber kneader such as a roll, a pressure kneader, a Banbury mixer, and an internal mixer. Thus, it is easily adjusted. At this time, it is preferable that the preliminarily vulcanized fluororubber and / or the compound thereof be used in the form of a sheet using a conventional rubber kneader or powdered using a pulverizer.

The rubber alloy composition of the present invention may be further provided with a reinforcing filler, a bulking filler, an antioxidant, a vulcanization stabilizer, a processing aid, if necessary, in order to provide a more favorable balance of physical properties and processability. Agents, coupling agents, plasticizers, pigments and the like. However, it is not preferable to add a compound which adversely affects the physical properties of the fluororubber and the acrylic rubber, especially the heat resistance.

The thus obtained rubber alloy composition of the present invention is molded by compression molding, injection molding, transfer molding, extrusion molding, coating dissolved in a solvent, etc., which are generally used in the rubber industry.

[0029]

The vulcanizate obtained by vulcanizing the rubber alloy composition of the present invention has excellent oil resistance close to that of fluororubber, heat resistance between fluororubber and acrylic rubber, and cold resistance superior to fluororubber. While having sex,
It has excellent compression set resistance, and can be manufactured at a lower cost than fluororubber and, depending on the method, at lower cost than acrylic rubber. Therefore, packing, gasket,
Widely used for oil seals, O-rings, valves, diaphragms, tubes, hoses, belts, rolls, roll blades, vibration isolating rubbers, coating materials, coating materials, etc., which require oil resistance, heat resistance, and cold resistance. can do.

[0030]

The present invention will be described below in detail with reference to examples. The present invention is not limited by this.

In the following description, parts are parts by weight.
The physical properties of the vulcanized rubber were evaluated according to JIS K6301. The heat resistance is 168 in a gear oven at 175 ° C.
Evaluation was made by measuring the rate of change of each physical property value after heat aging for a time. The compression set resistance is as follows.
The compression set of the sample at 175 ° C. for 24 hours after 5% compression was measured. The swelling volume change rate showing oil resistance was determined by measuring the change rate after immersing the vulcanized rubber in JIS # 3 oil at 150 ° C. for 70 hours. Cold resistance was measured in a TR test according to ASTM D1329-88.

The rubber alloy composition in this example was obtained as follows. That is, according to the composition shown in Table 1, each component was uniformly mixed with two rolls, and the fluororubber compound FK was mixed.
M1 to FKM9 were created. On the other hand, by emulsion polymerization, an acrylic resin having a copolymerization ratio of ethyl acrylate / butyl acrylate / methoxyethyl acrylate / 2-chloroethyl vinyl ether of 40/35/20/5 (weight ratio) and a Mooney viscosity ML1 + 4 (100 ° C) of 40 was used. Rubber ACM1 was obtained.

Next, after primary vulcanization (press vulcanization) and secondary vulcanization according to the composition shown in Table 2 and the vulcanization conditions shown in the footnote, a vulcanized rubber alloy composition was obtained. The vulcanization conditions of the rubber alloy composition to be vulcanized are the same from Tables 3 to 5 shown below.

Example 1 Based on 100 parts of a halogen-type acrylic rubber ACM1, 62 parts of a pre-vulcanized binary fluororubber compound FKM1-C1 (43 parts of a fluororubber) and 1 part of stearic acid , 1 part of substituted diphenylamine, FEF
60 parts of carbon, 2 parts of a triazine compound (vulcanizing agent 1) as a vulcanizing agent, and 2 parts of an organic onium compound (vulcanizing agent 2)
Department.

Example 2 Binary Fluoro Rubber Compound FK Preliminarily Vulcanized
144.4 parts of M1-C1 (fluorine rubber content: 100 parts)
Except that vulcanizing agent 1 and vulcanizing agent 2 were each 3.4 parts,
The same mixing ratio as in Example 1 was used.

Example 3 Binary Fluoro Rubber Compound FK Precured Primary
The same mixing ratio as in Example 1 was used except that M1-C1 was 337 parts (fluorine rubber content: 233 parts) and vulcanizing agent 1 and vulcanizing agent 2 were each 5.4 parts.

COMPARATIVE EXAMPLE 1 For comparison, a rubber containing only acrylic rubber ACM1 and a primary vulcanized two-element fluorine rubber compound FKM
1-C1 was not blended, and the other proportions were the same as in Example 1 above.

Comparative Example 2 For comparison, an unvulcanized rubber was used as a fluorine rubber compound FKM1 for comparison.
-C0 was only 144.4 parts.

Comparative Example 3 For comparison, an unvulcanized fluoro rubber compound FKM1-C0
Was used in place of FKM1-C1 except that FKM1-C1 was blended.

Evaluation The evaluation results of the normal vulcanizates, heat aging resistance, compression set, oil resistance and cold resistance of the secondary vulcanizates of Examples 1 to 3 and Comparative Examples 1 to 3 were as follows: The composition and vulcanization conditions are shown in Table 2 together.

As shown in Table 2, the hardness change, the tensile strength change rate, the elongation change rate, and the compression set rate of the rubber alloy composition of Example 1, which indicate the heat aging resistance, were each a single rubber. It is intermediate between Comparative Examples 1 and 2, which are secondary vulcanizates, and is excellent in heat aging resistance and compression set resistance. Further, the rubber alloy composition of Example 1 is more excellent in oil resistance than acrylic rubber (Comparative Example 1), more excellent in cold resistance than fluororubber (Comparative Example 2), and further, is an unvulcanized fluororubber compound. It was found to be superior in heat aging resistance and compression set resistance as compared with (Comparative Example 3).

The heat aging resistance and compression strain resistance of the rubber alloy compositions of Examples 2 and 3 are further improved than those of Example 1, and the oil resistance and cold resistance exhibit the same effects as described above. There was found.

Next, in Examples 4 to 7, the preparation conditions and forms of the fluororubber compound used were evaluated in the same manner as described above. Table 3 shows the composition and the evaluation results.

Example 4 A pre-vulcanized fluoro rubber compound FKM1-
Except that C2 was used instead of FKM1-C1, the same blending ratio as in Example 1 was used.

Example 5 The same blending ratio as in Example 1 was used except that FKM1-C1B, a non-burr product of a fluororubber compound generated by press vulcanization, was used instead of FKM1-C1.

Example 6 FKM1-C1B obtained by mechanically pulverizing burrs of a fluororubber compound generated by press vulcanization and sieving to 3 mm or less.
Was used in place of FKM1-C1 except that FKM1-C1 was used.

Example 7 FKM1-C1 obtained by mechanically pulverizing burrs of a fluororubber compound generated by press vulcanization and sieving to 100 μm or less.
Except that B was used instead of FKM1-C1, the blending ratio was the same as in Example 1 above.

Evaluation As shown in Table 3, the present invention was applied to both the pre-vulcanized fluororubber compound from Example 4 and the burr of the press-cured fluororubber compound from Example 5 The rubber alloy composition exhibits the same excellent characteristics as described above. From Examples 6 and 7, it was found that each of the pulverized burrs of the fluororubber compound had slightly improved properties.

Further, in Examples 8 to 11, when the fluororubber compound was a ternary fluororubber, when a pure rubber compound was used, when an amine vulcanization type compound was used, and when the rubber alloy composition was amine vulcanized, The case where the vulcanization system was a combination system of a triazine system and an amine was evaluated. Table 4 shows the composition including the comparative examples and the evaluation results.

Example 8 Formulation F of ternary fluororubber preliminarily vulcanized
Except that 63 parts of KM2-C1 were used instead of FKM1-C1, the blending ratio was the same as in Example 1 above.

Example 9 Pure rubber compound F of preliminarily vulcanized fluorine rubber
Except that 49 parts of KM9-C1 were used in place of FKM1-C1, the blending ratio was the same as in Example 1 above.

Example 10 A blend FM of 100 parts of an epoxy type acrylic rubber ACM2 and a tertiary fluorine rubber preliminarily vulcanized
Example 8 except that 58 parts of K8-C1 were used, and the vulcanization system was replaced with a triazine system (vulcanizing agent 1, vulcanizing agent 2) and an amine system (Diac No. 1) was changed to 1.5. The same blending ratio as in Example 1 was used.

Example 11 The vulcanization system was a triazine system (vulcanizing agent 1 and vulcanizing agent 2).
The same compounding ratio as in Example 1 was used, except that 5 parts and an amine (Diac No. 1) were used in combination with 1 part of each.

Comparative Example 4 For comparison, the rubber was epoxy-type acrylic rubber ACM.
Except that FKM8-C1 was not used for only 2, the same blending ratio as in Example 10 was used.

Comparative Example 5 For comparison, the blending ratio was the same as in Example 10 except that a blend FKM8-C0 of an epoxy type acrylic rubber ACM2 and an unvulcanized ternary fluororubber was used.

Evaluation From Examples 8 and 9, the same excellent characteristics as described above were obtained in comparison with Comparative Example 1 regardless of whether the fluororubber compound was a ternary fluororubber or a pure rubber compound. Demonstrate. Comparison of Comparative Example 4 and Comparative Example 5 of Example 10 shows that the rubber alloy composition of the present invention also has the above-mentioned excellent characteristics whether it is an epoxy type acrylic rubber or an amine vulcanized type. Demonstrate. Further, from Example 11, it was found that the above-mentioned excellent characteristics were similarly exhibited even when the vulcanization system was a combination system of a triazine system and an amine.

In Examples 12 to 16, the rubber vulcanized rubber composition was evaluated by peroxide vulcanization using a peroxide vulcanized type acrylic rubber ACM3 and various fluororubber compounds which were preliminarily vulcanized. As shown in Table 5,
Further, Comparative Examples 6 to 11 were compared with the respective examples.

Example 12 Binary Fluoro Rubber Compound FK Preliminarily Vulcanized
Except that 58 parts of M3-C1, 65 parts of FEF carbon, and 2 parts of a crosslinking assistant triallyl isocyanurate were used, and vulcanized with 2 parts of peroxide (peroximon F).
The same mixing ratio as in Example 1 was used.

Example 13 A ternary fluororubber compound FK which has been pre-vulcanized in advance
Except that 56 parts of M4-C1 was used in place of FKM3-C1, the blending ratio was the same as in Example 12 above.

Example 14 56 parts of a pre-vulcanized propylene-containing binary fluororubber compound FKM5-C1 was added to FKM3-C1
The same blending ratio as in Example 12 was used except for using in place of the above.

Example 15 The same blending ratio as in Example 12 was used, except that the propylene-containing ternary fluororubber compound FKM6-C1, which had been primary vulcanized in advance, was used instead of FKM3-C1.

Example 16 Perfluoro (methyl vinyl ether) -containing ternary fluororubber compound FKM7-C1 which had been previously vulcanized in advance
Was used in the same manner as in Example 12, except that 59 parts of was used instead of FKM3-C1.

Comparative Example 6 For comparison, the rubber was peroxide-cured acrylic rubber A
Except not using FKM3-C1 only as CM3, the blending ratio was the same as in Example 12 above.

Comparative Example 7 For comparison, an unvulcanized binary fluororubber compound FKM3 was used.
Except that -C0 was used instead of FKM3-C1, the blending ratio was the same as in Example 12 above.

Comparative Example 8 For comparison, an unvulcanized ternary fluororubber compound FKM4 was used.
Except that -C0 was used instead of FKM4-C1, the blending ratio was the same as in Example 13 above.

Comparative Example 9 For comparison, the same blending ratio as in Example 14 was used except that the unvulcanized propylene-containing binary fluororubber compound FKM5-C0 was used in place of FKM5-C1.

Comparative Example 10 For comparison, the blending ratio was the same as in Example 15 except that the unvulcanized propylene-containing ternary fluororubber compound FKM6-C0 was used instead of FKM6-C1.

Comparative Example 11 For comparison, an unvulcanized perfluoro (methyl vinyl ether) -containing ternary fluororubber compound FKM7-C0 was prepared as follows:
Example 15 except that FKM7-C1 was used instead of FKM7-C1.
The same mixing ratio was used.

Evaluation From Examples 12 to 16 and Comparative Examples 6 to 11, it can be seen that, even when fluororubber compounds having different compositions and which have been subjected to primary vulcanization beforehand are used, peroxide vulcanization can be performed. It was found that even in the case of peroxide-cured acrylic rubbers having different compositions, the rubber alloy compositions of these examples exhibited the same excellent characteristics as described above.

[0070]

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Takeya 3-30-1 Horikiri, Katsushika-ku, Tokyo Inside Arai Seisakusho Co., Ltd. (56) References JP-A-50-109979 (JP, A) JP-A-3 -139549 (JP, A) JP-A-9-137024 (JP, A) JP-A-5-287156 (JP, A) JP-A-2-245046 (JP, A) (58) Fields investigated (Int. . ^7, DB name) C08L 27/12 - 27/20 C08L 19/00 - 19/02 C08L 33/08 - 33/12

Claims (4)

(57) [Claims] 1. A vulcanizable rubber alloy composition comprising a pre-vulcanized fluororubber and / or a blend thereof in an acrylic rubber. 2. The rubber alloy composition according to claim 1, wherein the preliminarily vulcanized compound of fluororubber is burrs or scraps generated during the primary vulcanization molding. 3. The rubber alloy composition according to claim 1, wherein the amount of the pre-vulcanized fluoro rubber is 10 to 500 parts by weight per 100 parts by weight of the acrylic rubber. 4. A fluorine rubber which has been vulcanized in advance is a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, or a vinylidene fluoride-tetrafluoroethylene-perfluoropolymer. 4. The copolymer according to claim 1, wherein the copolymer is one or more of a (methyl vinyl ether) copolymer, a tetrafluoroethylene-propylene copolymer, and a tetrafluoroethylene-vinylidene fluoride-propylene copolymer. The rubber alloy composition according to any one of the preceding claims.