JP2002212342A - Rubber composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition improving the modulus of elasticity of a vulcanized rubber composition, having a slight reduction in processability in an unvulcanized compounded state. SOLUTION: This rubber composition is characterized in that a rubber component-containing matrix is compounded with a polyolefin premixed with a filler. The method for producing the rubber composition is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition and a method for producing the same. More specifically, the present invention relates to a method for improving the elastic modulus of a vulcanized rubber composition by blending a polyolefin containing a filler in advance. At the same time, the present invention relates to a rubber composition in which a decrease in workability in an unvulcanized compounded state is small and a method for producing the rubber composition.

[0002]

2. Description of the Related Art Conventionally, as a means for improving the elastic modulus of a vulcanized rubber composition, a resin having a higher elastic modulus than rubber has been used. Among them, polyolefins are inexpensive and have high compatibility with diene rubbers, and thus are widely used as compounded resin components.

For example, US Pat. No. 4,675,349 and US Pat. No. 5,341,863 have proposed rubber compositions for pneumatic tires containing polyethylene. The former is characterized by blending polyethylene having a softening point of 135 ° C. or higher at a temperature lower than its softening point. In this case, fine polyethylene particles must be added at the time of blending, and handling during blending is required. At the same time, the polyethylene particles may aggregate in the blend to lower the physical properties of the blend. The latter also
LDPE with melting point of crystal in the range of 104 ° C to 115 ° C
(Low-density polyethylene).

Japanese Patent Application Laid-Open No. Hei 7-266454 proposes a rubber composition containing low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). JP-A-10-67886 discloses that high-density polyethylene is used in an amount of 2 to 7 parts per 100 parts by mass of a rubber component.
A rubber composition in which 5 parts by mass (including 20% by mass or more of high-density polyethylene having a crosslinkable portion) is kneaded at a temperature higher than the melting point of the compounded resin has been proposed. Further, JP-A-11-60811 proposes a rubber composition containing a matrix containing a rubber component and a foaming agent, and a granular polyolefin resin.

However, when a rubber composition containing the above-mentioned polyolefin is subjected to shear deformation by a roll or the like during kneading at a high temperature, the softened polyolefin is stretched and fibrillated, so that the processability of the rubber composition is increased. Is significantly worsened. In this case, fibrillation can be prevented by increasing the molecular weight of the polyolefin to be compounded, but there is a problem that it is difficult to finely disperse such a high-molecular-weight polyolefin when compounded in a rubber composition.

[0006]

The object of the present invention is to solve the conventional problems in such a situation and to achieve the following objects. That is, according to the present invention, the elastic modulus of the vulcanized rubber composition is improved by blending a polyolefin premixed with a filler into a matrix containing a rubber component, and at the same time, processability in an unvulcanized blended state. It is an object of the present invention to provide a rubber composition having a small decrease in the rubber composition and a method for producing the rubber composition.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have mixed a filler with a polyolefin having a high elastic modulus relative to the rubber composition, and previously mixed the filler. By blending the obtained polyolefin into a matrix containing a rubber component, it is possible to obtain a rubber composition that can solve the problems of the conventional rubber composition blended with a polyolefin that has high elasticity and excellent processability. To complete the present invention.

That is, the present invention provides the following rubber composition and a method for producing the same. The invention according to claim 1 is a rubber composition characterized in that a polyolefin in which a filler is previously mixed is blended with a matrix containing a rubber component. The invention according to claim 2 is the rubber composition according to claim 1, wherein the polyolefin in which the filler is preliminarily mixed is obtained by mixing 10 to 150 parts by mass of the filler with respect to 100 parts by mass of the polyolefin. In the invention of claim 3, 1 to 75 parts by mass of a polyolefin in which a filler is previously mixed is blended with 100 parts by mass of the rubber component.
Or the rubber composition according to 2. The invention according to claim 4 is the rubber composition according to any one of claims 1 to 3, wherein the polyolefin is obtained by polymerizing one or more kinds selected from olefin monomers having 2 to 8 carbon atoms. It is. The invention according to claim 5 is the rubber composition according to any one of claims 1 to 4, wherein the polyolefin is a poly-α-olefin. The invention according to claim 6 is the rubber composition according to any one of claims 1 to 5, wherein one or more kinds selected from carbon black, silica, aluminum hydroxide, and clay are used as the filler. . The invention of claim 7 is that the polyolefin and the filler are kneaded, and the obtained filler is mixed in advance with the polyolefin and a matrix containing a rubber component at a temperature exceeding the melting point of the polyolefin. A method for producing a rubber composition. The invention according to claim 8 is the method for producing a rubber composition according to claim 7, wherein 10 to 150 parts by mass of a filler is added to 100 parts by mass of a polyolefin.
The ninth aspect of the present invention is the method for producing a rubber composition according to the seventh or eighth aspect, wherein 1 to 75 parts by mass of a polyolefin mixed with a filler in advance is mixed with 100 parts by mass of the rubber component.

According to the present invention, a polyolefin and a filler are kneaded, and the obtained filler is mixed in advance with a matrix containing a rubber component at a temperature exceeding the melting point of the polyolefin. By kneading, the softening of the polyolefins at the time of high-temperature kneading is suppressed, and the polyolefins are not deformed by the shearing force of a roll or the like at a high temperature and do not fibrillate. As a result, the processability of the compounded rubber composition is reduced. And a rubber composition which can solve the conventional problems excellent in processability while having high elasticity can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The rubber composition of the present invention is obtained by mixing a rubber-containing matrix with a polyolefin premixed with a filler, thereby improving the elastic modulus and simultaneously decreasing the processability in an unvulcanized compounded state. Is obtained. That is, although the elastic modulus of the rubber composition is improved by blending the polyolefin with the matrix containing the rubber component, such an effect is similarly obtained in the case of the polyolefin in which the filler is premixed, and the filler is used in advance with the polyolefin. If they are not mixed, even if they have high elasticity, the polyolefins will soften during high-temperature kneading, causing fibrillation due to shear deformation, and the workability will be significantly reduced. In addition, in the rubber composition,
Unvulcanized and after vulcanized are included.

The rubber composition of the present invention as described above can be obtained by blending a polyolefin in which a filler is previously mixed with a matrix containing a rubber component.

Here, the polyolefin in which the filler is mixed in advance is obtained by adding the filler to the polyolefin,
It can be obtained by kneading. In this case, in order to prevent softening and fibrillation of the polyolefin, kneading is not performed using a kneading machine having a shearing force such as a roll, but using a kneading machine such as a twin-screw kneading extruder. No, but usually 180-300
It is preferable to knead the mixture at about 5 to 10 minutes.

The amount of the filler added is 10
The filler is used in an amount of 10 to 150 parts by mass, preferably 50 to 100 parts by mass, based on 0 parts by mass. If the added amount of the filler is too large, the dispersibility in the polyolefin becomes poor, and the physical properties may be reduced. On the other hand, if the amount is too small, the effect of improving workability may not be sufficient.

As the polyolefin, those having a single-component polymer, those having a melting point controlled in an appropriate range by copolymerization, blending and the like can be used, and those obtained by adding an additive thereto can also be used. Among them, particularly, those having 2 to 2 carbon atoms
8, preferably a polymer of an olefin monomer having 2 to 6 carbon atoms, and more preferably a polymer of one or two or more monomers selected from ethylene, propylene, butylene and the like. In this case, the weight average molecular weight of the polyolefin is from 10,000 to 200,000, preferably from 30,000 to 150,000.

Such polyolefins include, for example, polyethylene (PE), polypropylene (PP),
Polybutylene, polybutylene succinate, polyethylene succinate, syndiotactic-1,2-polybutadiene (SPB), polyvinyl alcohol (PV
A) and polyvinyl chloride (PVC). These may be used alone or in combination of two or more. Among these polyolefins, poly-α-olefin is preferred, and polyethylene (PE) and polypropylene (PP) are preferred because they are widely available.

Specifically, polypropylene "Novatech PP MG05BS (trademark)" manufactured by Nippon Polychem Co., Ltd., high-density polyethylene "Hizex 5000SR (trademark)" manufactured by Mitsui Chemicals, Inc .; Linear low-density polyethylene "Ultzex 3021F
(Trademark) and commercially available products such as low-density polyethylene "Mirason 401 (trademark)" manufactured by Mitsui Chemicals, Inc., but are not limited thereto.

As the filler, one selected from carbon black, silica, aluminum hydroxide and clay can be used alone or in combination of two or more. In this case, the filler preferably has a particle size of 10 μm or less, more preferably 3 μm or less. By setting the particle size of the filler to 10 μm or less in this way,
Mixability with polyolefins can be improved.

As the carbon black, there are channel black, furnace black, acetylene black, thermal black and the like depending on the production method, and any of them can be used. This carbon black has a nitrogen adsorption specific surface area (BET) of 70 m ² / g.
And dibutyl phthalate oil absorption (DBP)
Is preferably 90 ml / 100 g or more.

This BET value is 70 m²/ G is enough
It is difficult to obtain abrasion resistance.
A more preferable range of the BET value is 90 m²/ G ~ 18
0m ²/ G. In addition, this BET value is ASTM D
It is a value measured according to 3037-88. Furthermore, D
If the BP value is less than 90 ml / 100 g, sufficient resistance
It is difficult to obtain abrasion, and the DBP value is too large.
If too large, the elongation at break of the rubber composition may deteriorate.
You. Considering wear resistance and elongation at break, this DBP
A more preferred range of values is 100-180 ml
/ 100 g. This DBP value is calculated according to JIS K
It is a value measured in accordance with 6221-1982 (Method A).
You.

The silica is not particularly limited and may be appropriately selected from those conventionally used for reinforcing rubber, for example, dry silica and wet silica (hydrous silica). Wet silica is preferred. This silica has a nitrogen adsorption specific surface area (BET) of 10
Those in the range of 0m ² / g~300m ² / g are preferred. The BET value was determined after drying at 300 ° C. for 1 hour.
It is a value measured according to STM D4820-93.

Specifically, "Nip Seal AQ" manufactured by Nippon Silica Industry Co., Ltd. and "ULTRAS" manufactured by Degussa AG
"IL VN3", "BV3370GR", "Zeosil 1165MP", "Zeosil" manufactured by Rhodia
165GR "," Zeosil 175P "," Hisil 233 "," Hisil 210 "manufactured by PPG,
A commercially available product such as "Hisil 255" can be used, but is not particularly limited.

Examples of the aluminum hydroxide include hydrated alumina (Al ₂ O ₃ .H ₂ O), gibbsite, and bayerite.

Next, the rubber composition of the present invention comprises a matrix containing a rubber component and a polyolefin in which the above-mentioned filler is preliminarily mixed.
The compounding amount of the polyolefin to which the filler is previously mixed is 1 to 75 parts by mass, preferably 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component. If the amount of the polyolefin in which the filler is previously mixed is too small, the effect of improving the elastic modulus may not be sufficient, while if too large, the processability may be adversely affected.

Here, the matrix of the rubber composition of the present invention contains a component other than polyolefins in which the filler is previously mixed in the rubber composition, and is specifically selected from natural rubber and diene-based synthetic rubber. And at least one rubber component, filler, softener, vulcanizing agent such as sulfur, vulcanization accelerator, antioxidant, zinc oxide, stearic acid, additives such as antiozonant, etc. Various compounding agents ordinarily used in the rubber industry can be appropriately used. These may be used alone or in combination of two or more.

Examples of the rubber component include natural rubber (NR) and diene-based synthetic rubber. Examples of the diene-based synthetic rubber include styrene-butadiene copolymer (SBR),
Polybutadiene rubber (BR), polyisoprene (I
R), butyl rubber (IIR), ethylene-propylene copolymer or a mixture thereof. Further, a part thereof may have a branched structure by using a polyfunctional modifier, for example, a modifier such as tin tetrachloride.

As the filler, any one can be selected from those conventionally used in rubber compositions, and carbon black, silica and the like are particularly preferable. As such carbon black or silica, the same filler as that mixed with the above-mentioned polyolefins can be used. When silica is used as the filler, it is preferable to add a silane coupling agent as desired. The amount of the filler is usually 20 to 120 parts by mass, preferably 25 to 80 parts by mass, per 100 parts by mass of the rubber component.

The softener is not particularly limited, and may be appropriately selected from those conventionally used as rubber softeners. This softener includes mineral oils,
Vegetable oils and synthetic oils are available, and mineral oils include, for example, naphthenic and paraffinic process oils. Examples of vegetable oils include castor oil, cottonseed oil,
Linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, wood wax, pine oil, olive oil and the like. Examples of the synthetic oils include polyisobutylene-based oils.

These softeners may be used alone or in combination of two or more. Further, the total compounding amount is usually preferably 100 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of the breaking characteristics of the vulcanized rubber, low heat build-up and the like.

Examples of the antioxidant include naphthylamine, p-phenylenediamine, hydroquinone derivatives, bis, tris, polyphenol, diphenylamine, quinoline, monophenol, thiobisphenol, hindered phenol and the like. Among these, a diphenylamine-based antioxidant and a p-phenylenediamine-based antioxidant are preferred from the viewpoint of further improving the antiaging effect.

The diphenylamine-based antioxidants include:
For example, 4,4 ′-(α-methylbenzyl) diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) diphenylamine, p- (p-toluenesulfonylamide) diphenylamine, 4,4′-dioctyldiphenylamine and the like Among them, 4,4 ′-(α-methylbenzyl) diphenylamine is most preferable from the viewpoint of a further anti-aging effect. Examples of the p-phenylenediamine-based antioxidant include N, N'-diphenyl-p-phenylenediamine and N-isopropyl-N '.
-Phenyl-p-phenylenediamine, N, N'-di-
2-naphthyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, N
-Phenyl-N '-(3-methacryloyloxy-2-
(Hydroxypropyl) -p-phenylenediamine, N,
N'-bis (1-methylheptyl) -p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl)
-P-phenylenediamine, N, N'-bis (1-ethyl-3-methylpentyl) -p-phenylenediamine,
N- (1,3-dimethylbutyl) -N′-phenyl-p
And N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine is most preferable from the viewpoints of further preventing aging and cost.

The compounding amount of these antioxidants is as follows:
The amount is used in the range of 0.1 to 5.0 parts by mass, preferably 0.2 to 4.0 parts by mass, per 100 parts by mass. When the amount of the antioxidant is less than 0.1 part by mass, a higher antiaging effect may not be exhibited. On the other hand, when the amount exceeds 5.0 parts by mass, the effect may not only be saturated but may not be economical.

The vulcanization accelerator that can be used in the present invention is not particularly limited, and any known vulcanization accelerator can be used. Examples thereof include benzothiazoles, benzothiazolylsulfenamides, and benzothiazolylsulfenimides. , Thioureas, guanidines, aldehydeamines, dithiophosphates, dithiocarbamates, xanthates,
Preferred are thiurams, and these may be used alone or in combination of two or more depending on the purpose.

Specifically, the vulcanization accelerators belonging to benzothiazoles, benzothiazolylsulfenamides, and benzothiazolylsulfenimides include dibenzothiazyl disulfide, N-tert-butyl-2-benzo. Thiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, N-ter
t-butyl-di (2-benzothiazothiazolylsulfen) imide, bis (4-methylbenzothiazolyl-2)
-Disulfide and the like. Examples of the vulcanization accelerator belonging to zinc dithiophosphates include zinc diisopropyldithiophosphate, zinc di-n-butyldithiophosphate, and zinc di-isobutyldithiophosphate. Examples of the vulcanization accelerator belonging to thiurams include tetrabenzylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, and the like. As the vulcanization accelerator belonging to the dithiophosphoric acid polysulfides, bis (di-isopropylthiophosphoryl) disulfide,
Bis (di-isobutylthiophosphoryl) disulfide and the like can be mentioned. As the vulcanization accelerator belonging to zinc dithiocarbamate, zinc dibutyldithiocarbamate,
Zinc N-ethyl-N-phenyldithiocarbamate, N
-Zinc pentamethyldithiocarbamate, zinc dibenzyldithiocarbamate and the like. The amount of these vulcanization accelerators is 0.1 to 100 parts by mass of the rubber component.
To 5 parts by mass, preferably 0.2 to 3 parts by mass.

Next, the method for producing the rubber composition of the present invention comprises:
The polyolefins and the filler are kneaded using a kneader such as a twin-screw extruder, and the obtained filler is mixed in advance with a polyolefin and a matrix containing the rubber component, which exceeds the melting point of the polyolefin used. The compound is mixed after confirming that the temperature has been reached, and is kneaded with a kneading machine such as a roll or an internal mixer while maintaining this temperature.

In this case, the polyolefin to which the filler has been previously mixed is preferably mixed with the filler in an amount of 10 to 150 parts by weight, particularly 50 to 100 parts by weight, based on 100 parts by weight of the polyolefin. Further, it is preferable to mix 1 to 75 parts by mass, particularly 1 to 20 parts by mass of a polyolefin in which a filler is previously mixed with 100 parts by mass of the rubber component.

It is also possible to mix and knead a polyolefin premixed with a filler and a matrix containing a rubber component at a temperature higher than the melting point of the polyolefin used by at least 5 ° C., especially at least 10 ° C., and kneading. It is preferable from the viewpoints of properties and affinity with the matrix. The kneading conditions vary depending on the type of the polyolefin and cannot be specified unconditionally, but it is usually preferable to knead the polyolefin at a temperature not lower than the melting point to 160 ° C for about 2 to 8 minutes.

The rubber composition of the present invention is kneaded and molded as described above, and then vulcanized. The rubber composition is used in tires such as tire treads, undertreads, carcass, sidewalls, and bead portions. It can be widely used for applications such as vibration rubber, belts, hoses, and other industrial products.

[0038]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples 1 to 4 and Comparative Examples 1 to 8 First, the corresponding fillers and polyolefins shown in Tables 1 to 4 were mixed at 180 to 300 ° C. using a twin-screw kneading extruder.
And kneaded for 5 to 10 minutes to prepare a filled polyolefin.

Next, rubber compositions were prepared according to the formulation shown in Tables 1 to 4 and vulcanized. The compounding was divided into a master batch and a final batch. For those containing polyolefins and filled polyolefins, the melting point of the polyolefins was 5
Check that the temperature exceeds ℃ and mix.
While maintaining this temperature, the mixture was kneaded for 2 to 8 minutes using a roll.

The physical properties of the obtained rubber compositions of Examples 1 to 4 and Comparative Examples 1 to 8 were evaluated according to the following methods. The results are shown in Tables 5 and 6.

<Evaluation of Processability> The processability (degree of fibrillation of polyolefins) of the unvulcanized rubber composition was evaluated by the Mooney viscosity measured under the following conditions. The Mooney viscosity was measured according to JIS K6300-1994 using an RLM-01 type tester manufactured by Toyo Seiki Co., Ltd., and ML _{1 + 4} was measured at a measurement temperature (100 ° C.) lower than the softening point of polyolefins.

<Evaluation of Elastic Modulus> A rubber sample was vulcanized and molded to prepare a cylindrical sample, and a cylindrical sample was prepared using a viscoelasticity measuring apparatus at a temperature of 50 ° C., a frequency of 15 Hz, and a shear strain of 10%. The stress was measured.

[0044]

[Table 1] * SBR0120: Trademark, manufactured by JSR Corporation
Styrene-butadiene copolymer * Nip Seal AQ: Trademark, silica (manufactured by Nippon Silica Industry Co., Ltd.) * SAF C / B (N234 Seast 7HM): trademark, carbon black (manufactured by Tokai Carbon Co., Ltd.) * Si69: trademark, Silane coupling agent (Degussa AG
* Aging inhibitor 6C: N- (1,3-dimethylbutyl)-
N'-phenyl-p-phenylenediamine (Nocrack 6 (trademark) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) * Polypropylene: manufactured by Nippon Polychem Co., Ltd., Novatec PP MG05BS (trademark), deflection temperature under load = 105
° C (0.45 MPa, according to ASTM D648), melt flow rate = 45 g / 10 min * Polypropylene with filler: above polypropylene + clay (compounding ratio by mass ratio 1: 1) * DPG: vulcanization accelerator, diphenylguanidine * DM: Vulcanization accelerator, dibenzothiazolyl disulfide * NS: Vulcanization accelerator, Nt-butyl-2-benzothiazylsulfenamide

[0045]

[Table 2] * BR01: Trademark, cis-1,4-polybutadiene (manufactured by JSR Corporation) * RSS # 3: Natural rubber * Tackfire (Nisseki Neopolymer B100): Trademark, manufactured by Nippon Synthetic Resins Co., Ltd., aromatic -Based petroleum resin * High-density polyethylene: manufactured by Mitsui Chemicals, Inc., Hyzex 5000SR (trademark), melting point = 132 ° C, melt flow rate = 0.35 g / 10 min * High-density polyethylene with filler: high-density polyethylene + HAF C / B (manufactured by Tokai Carbon Co., Ltd., N33
9 Seast KH (trademark)) (compounding ratio mass ratio 1: 1) * CZ: vulcanization accelerator, Norac CZ (trademark) (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0046]

[Table 3] * # 1500: Trademark, styrene-butadiene rubber (manufactured by JSR Corporation) * HAF C / B (N339 Seast KH): Trademark,
Carbon black (manufactured by Tokai Carbon Co., Ltd.) * Linear low-density polyethylene: manufactured by Mitsui Chemicals, Inc., Ultrazex 3021F (trademark), melting point = 123 ° C., melt flow rate = 2.1 g / 10 min * filled directly with filler Chain low-density polyethylene: The above-mentioned linear low-density polyethylene + silica (Nip Seal AQ (trademark);
Nippon Silica Industry Co., Ltd.)

[0047]

[Table 4] * Low-density polyethylene: Mirason, manufactured by Mitsui Chemicals, Inc.
401 (trademark), melting point = 105 ° C., melt flow rate = 1.6 g / 10 min * Low-density polyethylene with filler: low-density polyethylene + aluminum hydroxide (Heidilite H-43M)
(Trademark), manufactured by Showa Denko KK (Blending ratio, mass ratio 1:
1)

[0048]

[Table 5]

[0049]

[Table 6]

As is clear from the results of Tables 5 and 6, the rubber composition of Comparative Example 2 containing the polyolefin has an improved elastic modulus as compared with the rubber composition of Comparative Example 1 containing no polyolefin. However, while the processability is remarkably reduced, the rubber composition of Example 1 in which a polyolefin premixed with a filler is blended, while maintaining a high elasticity modulus, suppresses the reduction in processability without fail. It was confirmed that it was possible. This also applies to the rubber composition of Comparative Example 3, the rubber composition of Comparative Example 4, and the rubber composition of Example 2, the rubber composition of Comparative Example 5, the rubber composition of Comparative Example 6, and the rubber composition of Example 3. The rubber composition, the rubber composition of Comparative Example 7, the rubber composition of Comparative Example 8, and the rubber composition of Example 4 are also compared to each other.

[0051]

According to the present invention, the elastic modulus of the vulcanized rubber composition is improved by blending a polyolefin preliminarily mixed with a filler into a matrix containing a rubber component. It is possible to obtain a rubber composition with less decrease in processability.

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Claims (9)

[Claims] 1. A rubber composition comprising a matrix containing a rubber component and a polyolefin premixed with a filler. 2. The rubber composition according to claim 1, wherein the polyolefin to which the filler is previously mixed is a mixture of 10 to 150 parts by weight of the filler with respect to 100 parts by weight of the polyolefin. 3. The rubber composition according to claim 1, wherein 1 to 75 parts by mass of a polyolefin mixed with a filler in advance is mixed with 100 parts by mass of the rubber component. 4. The rubber composition according to claim 1, wherein the polyolefin is obtained by polymerizing one or more kinds of olefin monomers having 2 to 8 carbon atoms. 5. The rubber composition according to claim 1, wherein the polyolefin is a poly-α-olefin. 6. The rubber composition according to claim 1, wherein one or more selected from carbon black, silica, aluminum hydroxide and clay are used as the filler. 7. Kneading a polyolefin and a filler, blending the obtained filler in advance with a polyolefin and a matrix containing a rubber component at a temperature exceeding the melting point of the polyolefin, and kneading. A method for producing a rubber composition, comprising: 8. The method for producing a rubber composition according to claim 7, wherein 10 to 150 parts by mass of a filler is added to 100 parts by mass of the polyolefin. 9. The method for producing a rubber composition according to claim 7, wherein 1 to 75 parts by mass of a polyolefin mixed with a filler in advance is mixed with 100 parts by mass of the rubber component.