JP2014098102A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition capable of obtaining a rubber elastic body having excellent cracking resistance and favorable workability.SOLUTION: There is provided a rubber composition which comprises: (A) a component composed of 1,2-polybutadiene having a 1,2 bond content of 90% or more and a melting point of 100°C or more; and (B) a component composed of a vulcanizable rubber other than the (A) component. Further, there is provided a rubber composition which comprises: (A) a component composed of 1,2-polybutadiene having a melting point of 100°C or more; and (C) a component composed of at least one selected from a thermoplastic resin and a thermoplastic elastomer.

Description

  The present invention relates to a rubber composition, and more particularly to a rubber composition suitable as a material constituting a sidewall or a tread of a tire.

For example, rubber elastic bodies used for tire treads and sidewalls are required to have excellent crack resistance. As a rubber composition from which a rubber elastic body having such crack resistance is obtained, conventionally, polybutadiene having a cis 1,4 bond content of, for example, 92% or more (hereinafter also referred to as “high cis 1,4-polybutadiene”). ) And natural rubber or other diene rubbers (see, for example, Patent Document 1).
However, a rubber composition containing high-cis 1,4-polybutadiene as a rubber component has a problem that processability is low.

In addition, various characteristics are required for rubber elastic bodies used in tires according to specific applications. For example, a rubber elastic body constituting a tread is required to have wear resistance, wet skid property, and the like. In addition, the rubber elastic body constituting the side wall is required to have a high tensile elastic modulus.
However, there is no known rubber composition capable of obtaining a rubber elastic body that satisfies the properties according to the use in addition to the crack resistance and processability.

International Publication No. 2007/094370

  The present invention has been made on the basis of the circumstances as described above, and its purpose is to obtain a rubber elastic body having excellent crack resistance, to obtain good workability, and to use. An object of the present invention is to provide a rubber composition capable of obtaining appropriate characteristics.

  The rubber composition of the present invention comprises a component (A) comprising 1,2-polybutadiene having a 1,2 bond content of 90% or more and a melting point of 100 ° C. or more, and a vulcanization other than the component (A). (B) component which consists of possible rubber | gum, It is characterized by the above-mentioned.

  The rubber composition of the present invention has a component (A) composed of 1,2-polybutadiene having a 1,2 bond content of 90% or higher and a melting point of 100 ° C. or higher, and components other than the component (A). (C) component which consists of at least 1 type chosen from a thermoplastic resin and a thermoplastic elastomer, It is characterized by the above-mentioned.

  The rubber composition of the present invention has a component (A) composed of 1,2-polybutadiene having a 1,2 bond content of 90% or higher and a melting point of 100 ° C. or higher, and components other than the component (A). (B) component which consists of rubber | gum which can be vulcanized, and (C) component which consists of at least 1 type chosen from thermoplastic resins and thermoplastic elastomers other than the said (A) component, It is characterized by the above-mentioned.

  According to the rubber composition of the present invention, the component (A) composed of a specific 1,2-polybutadiene, the component (B) composed of a vulcanizable rubber other than the component (A), and a plastic resin And containing at least one component of component (C) consisting of at least one selected from thermoplastic elastomers, a rubber elastic body having excellent crack resistance is obtained, and good processability is obtained, It is possible to obtain a rubber elastic body that satisfies characteristics according to the application.

Embodiments of the present invention will be described below.
<Polymer component>
The rubber composition of the present invention comprises 1,2-polybutadiene (hereinafter referred to as “specific 1,2-polybutadiene”) having a 1,2 bond content of 90% or more and a melting point of 100 ° C. or more (hereinafter referred to as “specific 1,2-polybutadiene”). The component (A) contains at least one selected from the component (B) made of vulcanizable rubber other than the component (A), and a thermoplastic resin and thermoplastic elastomer other than the component (A) (C) )) Containing at least one polymer component.

≪ (A) component≫
The specific 1,2-polybutadiene constituting the component (A) has a 1,2 bond content of 90% or more. When 1,2-polybutadiene having a 1,2 bond content of less than 90% is used, the resulting rubber elastic body has poor crack growth resistance. In the present invention, “1,2 bond content” is a value determined by an infrared absorption spectrum method (Morello method). The specific 1,2-polybutadiene constituting the component (A) has a melting point of 100 ° C. or higher, preferably 100 to 200 ° C. When 1,2-polybutadiene having a melting point of less than 100 ° C. is used, the heat resistance of the resulting rubber elastic body is impaired, and the design range of the compounding recipe is narrowed. In the present invention, the “melting point” is a value measured according to ASTM D3418.

The specific 1,2-polybutadiene constituting the component (A) preferably has a crystallinity of 15 to 50%, more preferably 18 to 40%. When this crystallinity is too small, good crack growth resistance may not be obtained. On the other hand, when the crystallinity is excessive, it is necessary to prepare the rubber composition at a high temperature, and thus heat deterioration and scorch may occur, thereby reducing workability. In the present invention, “crystallinity” refers to the density of 1,2-polybutadiene having a crystallinity of 0% of 0.892 g / cm ³ and the density of 1,2-polybutadiene having a crystallinity of 100% of 0.963 g. / Cm ³ is a value obtained by a density gradient tube method.

  The specific 1,2-polybutadiene constituting the component (A) preferably has a weight average molecular weight (Mw) of 10,000 to 5,000,000, more preferably 10,000 to 1,500,000, still more preferably 50,000. ~ 1 million. When the weight average molecular weight (Mw) is less than 10,000, the fluidity becomes too high when heated and melted, and the processability tends to decrease. On the other hand, when the weight average molecular weight (Mw) is more than 5 million, the fluidity is lowered when heated and melted, and the processability tends to be lowered.

The specific 1,2-polybutadiene constituting the component (A) may contain a small amount of structural units derived from conjugated dienes other than butadiene. As conjugated dienes other than butadiene, 1,3-pentadiene, 1,3-butadiene derivatives substituted with higher alkyl groups, 2-alkyl-substituted-1,3-butadiene, and the like can be used.
Specific examples of 1,3-butadiene derivatives substituted with a higher alkyl group include 1-pentyl-1,3-butadiene, 1-hexyl-1,3-butadiene, 1-heptyl-1,3-butadiene, 1 -Octyl-1,3-butadiene and the like can be mentioned.
Specific examples of 2-alkyl-substituted-1,3-butadiene include 2-methyl-1,3-butadiene (isoprene), 2-ethyl-1,3-butadiene, and 2-propyl-1,3-butadiene. 2-isopropyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-isobutyl-1,3-butadiene, 2-amyl-1,3-butadiene, 2-isoamyl-1,3-butadiene 2-hexyl-1,3-butadiene, 2-cyclohexyl-1,3-butadiene, 2-isohexyl-1,3-butadiene, 2-heptyl-1,3-butadiene, 2-isoheptyl-1,3-butadiene 2-octyl-1,3-butadiene, 2-isooctyl-1,3-butadiene and the like.
Among the conjugated dienes other than butadiene described above, isoprene and 1,3-pentadiene are preferable.

The proportion of the component (A) in the polymer component of the rubber composition of the present invention is preferably 2% by mass or more, more preferably 5% by mass or more. When the proportion of the component (A) is less than 2% by mass, good crack growth resistance may not be obtained.
On the other hand, the upper limit of the ratio of the component (A) varies depending on the use of the obtained rubber elastic body. For example, when used for tread, base tread, sidewall, cap toledo, and cord coating, the proportion of component (A) is preferably 60% by mass or less, and more preferably 50% by mass or less. When the proportion of the component (A) exceeds 60% by mass, functions as an elastic body such as rebound resilience or mechanical strength may be impaired.
Moreover, when using for a tire case, it is preferable that the ratio of (A) component is 90 mass% or less, More preferably, it is 85 mass% or less. (A) When the ratio of a component exceeds 90 mass%, a burning defect may arise by heat molding processes, such as injection molding.

  The specific 1,2-polybutadiene constituting the component (A) preferably has a syndiotactic structure. Such specific 1,2-polybutadiene can be obtained, for example, by polymerizing butadiene in the presence of a polymerization catalyst containing a cobalt compound and an aluminoxane.

As the cobalt compound constituting the polymerization catalyst, an organic acid salt of an organic acid having 4 or more carbon atoms and cobalt can be preferably used.
Specific examples of such organic acid salts include butyrate, hexanoate, heptylate, octylate such as 2-ethylhexylic acid, decanoate, stearate, oleate, and erucate. Fatty acid salt, benzoate, benzoate substituted with alkyl group, aralkyl group or allyl group, such as tolylate, xylate, ethylbenzoate, naphthoate substituted with alkyl group, aralkyl group or allyl group There may be mentioned acid salts. Among these, octylates such as 2-ethylhexylic acid, stearates and benzoates are preferable because they have excellent solubility in hydrocarbon solvents.

  As aluminoxane which comprises the said polymerization catalyst, what is represented by the following general formula (1) or the following general formula (2) can be used, for example.

In the general formula (1) and the general formula (2), R ^{1 s} are each independently a methyl group, an ethyl group, a propyl group or a butyl group, preferably a methyl group or an ethyl group, and particularly preferably a methyl group. It is. M is an integer of 2 or more, preferably 5 or more, more preferably 10 to 100.

  Specific examples of such aluminoxane include methylaluminoxane, ethylaluminoxane, propylaluminoxane, butylaluminoxane and the like. Of these, methylaluminoxane is preferred.

  The polymerization catalyst preferably contains a phosphine compound in addition to the cobalt compound and aluminoxane. This phosphine compound is an effective component for activating the polymerization catalyst, controlling the vinyl bond structure and crystallinity. As such a phosphine compound, an organic phosphorus compound represented by the following general formula (3) can be used.

In the general formula (3), R ² represents a cycloalkyl group or an alkyl-substituted cycloalkyl group, n is an integer of 0 to 3, and Ar represents a group represented by the following general formula (4).

In the general formula (4), R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group, a halogen atom, an alkoxy group or an aryl group.
Of the groups represented by R ³ , R ⁴ and R ⁵ in the general formula (4), the alkyl group is preferably an alkyl group having 1 to 6 carbon atoms. Of the groups represented by R ³ , R ⁴ and R ⁵ , the alkoxy group is preferably an alkoxy group having 1 to 6 carbon atoms. Furthermore, among the groups represented by R ³ , R ⁴ and R ⁵ , the aryl group is preferably an aryl group having 6 to 12 carbon atoms.

  Specific examples of the organophosphorus compound represented by the general formula (3) include tris (3-methylphenyl) phosphine, tris (3-ethylphenyl) phosphine, tris (3,5-dimethylphenyl) phosphine, tris ( 3,4-dimethylphenyl) phosphine, tris (3-isopropylphenyl) phosphine, tris (3-t-butylphenyl) phosphine, tris (3,5-diethylphenyl) phosphine, tris (3-methyl-5-ethylphenyl) ) Phosphine), tris (3-phenylphenyl) phosphine, tris (3,4,5-trimethylphenyl) phosphine, tris (4-methoxy-3,5-dimethylphenyl) phosphine, tris (4-ethoxy-3,5) -Diethylphenyl) phosphine, tris (4-butoxy-3,5-di Butylphenyl) phosphine, tri (p- methoxyphenyl) phosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, tribenzylphosphine, tri (4-methylphenyl) phosphine, tri (4-ethylphenyl) phosphine and the like. Of these, triphenylphosphine, tris (3-methylphenyl) phosphine, tris (4-methoxy-3,5-dimethylphenyl) phosphine and the like are particularly preferable.

  Moreover, as a polymerization catalyst, the cobalt compound represented by following General formula (5) can also be used.

In the general formula (5), R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group, a halogen atom, an alkoxy group or an aryl group.

  The compound represented by the general formula (5) is a complex having, as a ligand, a phosphine compound in which n is 3 in the general formula (3) with respect to cobalt chloride. When this cobalt compound is used, one synthesized in advance may be used, or it may be used by contacting cobalt chloride with a phosphine compound in the polymerization system. By selecting various phosphine compounds in the complex, the 1,2-vinyl bond content and crystallinity of the resulting syndiotactic 1,2-polybutadiene can be controlled.

  Specific examples of the cobalt compound represented by the general formula (5) include cobalt bis (triphenylphosphine) dichloride, cobalt bis [tris (3-methylphenylphosphine)] dichloride, cobalt bis [tris (3,5- Dimethylphenylphosphine)] dichloride, cobalt bis [tris (4-methoxy-3,5-dimethylphenylphosphine)] dichloride, and the like.

The amount of cobalt compound used is equivalent to cobalt atom per mole of butadiene when homopolymerizing butadiene, and per mole of total amount of butadiene and other conjugated dienes when copolymerizing butadiene and other conjugated dienes. The amount is preferably 0.001 to 1 mmol, and more preferably 0.01 to 0.5 mmol.
The amount of the phosphine compound used is such that the ratio of phosphorus atom to cobalt atom (P / Co) in the cobalt compound is usually 0.1 to 50, preferably 0.5 to 20, and more preferably 1 to 20. It is.
Further, the amount of aluminoxane used is such that the ratio of aluminum atoms to cobalt atoms (Al / Co) in the cobalt compound is usually 4 to 107, preferably 10 to 106.
When the compound represented by the general formula (5) is used as a polymerization catalyst, the ratio of phosphorus atom to cobalt atom (P / Co) is 2, and the amount of aluminoxane used is as described above. It is a range.

  Polymerization solvents include aromatic hydrocarbon solvents such as benzene, toluene, xylene and cumene, aliphatic hydrocarbon solvents such as n-pentane, n-hexane and n-butane, and fats such as cyclopentane, methylcyclopentane and cyclohexane. Cyclic hydrocarbon solvents and mixtures thereof can be used.

  The polymerization temperature is preferably -50 to 120 ° C, more preferably -20 to 100 ° C. The polymerization reaction may be batch or continuous. Moreover, it is preferable that the monomer concentration in a solvent is 5-50 mass%, and it is still more preferable that it is 10-35 mass%.

  In order to prevent the catalyst and the polymer from being deactivated in the production of the polymer, consideration should be given so as to minimize the mixing of a deactivating compound such as oxygen, water, or carbon dioxide into the polymerization system. Is preferred. When the polymerization reaction has progressed to the desired stage, alcohol, other polymerization terminators, anti-aging agents, antioxidants, UV absorbers, etc. are added to the reaction mixture, and then the produced polymer is separated and washed according to ordinary methods. By drying, a specific 1,2-polybutadiene having a syndiotactic structure can be obtained.

  Examples of the commercially available specific 1,2-polybutadiene having a syndiotactic structure include “RB830” and “RB840” manufactured by JSR.

≪ (B) component≫
The component (B) is a component made of vulcanizable rubber other than the component (A). This component (B) is preferably used when the obtained rubber elastic body is used for a tread, a base tread, a sidewall, a cap toledo, or a cord coating.
As the vulcanizable rubber constituting the component (B), polybutadiene other than the component (A), styrene-butadiene copolymer rubber, natural rubber, isoprene rubber, butyl rubber, ethylene-α-olefin copolymer rubber, ethylene-α -Olefin-diene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber and halogenated butyl rubber, hydrogenated modified products thereof, and mixtures thereof can be used. Among these, polybutadiene other than the component (A), styrene-butadiene copolymer rubber, natural rubber, isoprene rubber, and mixtures thereof are preferable.

The proportion of the component (B) in the rubber component of the rubber composition of the present invention is preferably 98% by mass or less, more preferably 95% by mass or less. When the proportion of the component (B) exceeds 98% by mass, a rubber elastic body having good crack growth resistance may not be obtained.
On the other hand, the lower limit of the ratio of the component (B) varies depending on the use of the obtained rubber elastic body. For example, when used for tread, base tread, sidewall, cap toledo, and cord coating, the ratio of the component (B) is preferably 50% by mass or more, and more preferably 60% by mass or more. When the proportion of the component (B) is less than 50% by mass, functions as an elastic body such as rebound resilience or mechanical strength are impaired. Moreover, when using for a tire case, (B) component does not need to contain.

≪ (C) component≫
Component (C) is at least one polymer selected from thermoplastic resins and thermoplastic elastomers other than component (A) (hereinafter also referred to as “other thermoplastic polymer”). This component (C) is preferably used when the rubber elastic body obtained is used for a tire case.
Other thermoplastic polymers constituting the component (C) include thermoplastic resins such as polyolefin resins, polystyrene resins, nylon resins, polycarbonate resins, polyamide thermoplastic elastomers, polyester thermoplastic elastomers, polystyrene. A thermoplastic thermoplastic elastomer, a polyurethane thermoplastic elastomer, or the like can be used. Of these, nylon resins, polyamide thermoplastic elastomers, polyester thermoplastic elastomers, and polystyrene thermoplastic elastomers are preferred.
Specific examples of the polystyrene-based thermoplastic elastomer include hydrogenated styrene-butadiene-styrene block copolymer (SEBS).

The proportion of the component (C) in the rubber component of the rubber composition of the present invention is preferably 90% by mass or less, and more preferably 85% by mass or less. When the proportion of the component (C) exceeds 90% by mass, the resulting rubber elastic body has poor crack growth resistance and tensile strength.
On the other hand, the lower limit of the ratio of the component (C) varies depending on the use of the obtained rubber elastic body. For example, when used for a tire case, the proportion of the component (C) is preferably 10% by mass or more, and more preferably 15% by mass or more. (C) When the ratio of a component is less than 10 mass%, a burning defect will arise by heat molding processes, such as injection molding. Moreover, when using for a tread, a base tread, a side wall, a cap toledo, and a cord coating, (C) component does not need to contain.

<Filler>
In the rubber composition of this invention, a filler can be contained other than said (A) component-(C) component. As such a filler, silica and carbon black can be used.
Specific examples of the silica used for the filler include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate and the like. These silicas can be used alone or in combination of two or more. Of these, wet silica is preferred.
Specific examples of the carbon black used for the filler include carbon blacks of various grades such as SRF, GPF, FEF, HAF, ISAF, and SAF. These carbon blacks can be used alone or in combination of two or more. Of these, HAF, ISAF, and SAF are preferred because excellent wear resistance can be obtained.
Carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate oil absorption (DBP) of 80 ml / 100 g or more is preferable. By using such carbon black, grip performance and fracture resistance of the resulting rubber composition are improved.
The use ratio of the filler is 10 to 200 parts by mass, preferably 25 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

Moreover, when using silica as a filler, a silane coupling agent may be contained.
Specific examples of the silane coupling agent include, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (2 -Triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2 -Mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane;
3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-di Ethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetrasulfur It de, can be given dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide and the like. These silane coupling agents can be used alone or in combination of two or more. Of these, bis (3-triethoxysilylpropyl) polysulfide and 3-trimethoxysilylpropylbenzothiazyltetrasulfide are preferable from the viewpoint of reinforcing effect and the like.
It is preferable that the usage-amount of a silane coupling agent is 0.5-20 mass parts with respect to 100 mass parts of silica.

<Other ingredients>
In the rubber composition of the present invention, various additives can be contained in addition to the components (A) to (C) and the filler. Examples of such additives include vulcanizing agents, vulcanizing aids, processing aids, vulcanization accelerators, extender oils, anti-aging agents, surface cracking inhibitors, scorch preventing agents, zinc oxide, stearic acid, Cobalt stearate or the like can be used.

As the vulcanizing agent, sulfur is usually used. The use ratio of the vulcanizing agent is preferably 0.1 to 3 parts by mass, and more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass of the vulcanizable rubber component.
As the vulcanization aid and processing aid, stearic acid is generally used, and the use ratio thereof is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the vulcanizable rubber component.
Further, the vulcanization accelerator is not particularly limited, but is a thiazole type such as M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-benzothiazylsulfenamide). A preferred example is a vulcanization accelerator. The use ratio of the vulcanization accelerator is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

<Preparation of rubber composition>
The rubber composition of the present invention is prepared by heating and kneading the polymer component comprising the above component (A) and component (B) or component (C), and a filler and other components used as necessary. Is done. Examples of the kneader used for the preparation of the rubber composition include open or closed kneaders such as a plast mill, a Banbury mixer, a roll, and an internal mixer.
The kneading temperature of each component is set in consideration of the temperature of the specific 1,2-polybutadiene constituting the component (A) and the other thermoplastic polymer constituting the component (C).
Such a rubber composition has good processability because the Mooney viscosity (ML _{1 + 4} , 100 ° C.) is in the range of 40 to 50, for example.

<Rubber elastic body>
In the rubber composition containing the component (B) in the rubber composition of the present invention, a rubber elastic body can be obtained by crosslinking treatment. Such a rubber elastic body has excellent crack resistance, and has characteristics according to the application by adjusting the ratio of the component (B) and the component (C). It is suitable as a rubber elastic body used for the sidewall.
Moreover, in the rubber composition containing (C) component among the rubber compositions of this invention, it can be used as a rubber elastic body, without performing a crosslinking process. Such a rubber elastic body is suitable as a material constituting the tire case.

Specific examples of the present invention will be described below, but the present invention is not limited to these examples.
In the following examples and comparative examples, the methods for measuring various physical property values are as follows.

[1,2 bond content]
It measured by the infrared absorption spectrum method (Morello method) using the infrared spectrophotometer ("FT / IR-7300 type | mold infrared spectrophotometer" by JASCO Corporation).
[Crystallinity]
The density of the 1,2-polybutadiene having a crystallinity of 0% was 0.892 g / cm ³ and the density of the 1,2-polybutadiene having a crystallinity of 100% was 0.963 g / cm ³ . .
[Melting point]
Measured according to ASTM D3418.
[Weight average molecular weight]
The weight average molecular weight in terms of polystyrene was calculated using gel permeation chromatography (GPC) (“HLC-8120” manufactured by Tosoh Corporation).

<Example 1>
A rubber composition for a tread was produced as follows using a plastmill equipped with a temperature control device.
(A) 1,2-polybutadiene “RB840” having a syndiotactic structure as a component (manufactured by JSR, 1,2 bond content = 94%, crystallinity = 36%, melting point = 126 ° C., weight average molecular weight = 150,000, hereinafter referred to as “specific 1,2-polybutadiene (A1).” 10 parts by mass, as component (B) polybutadiene (“BR01” manufactured by JSR, cis 1,4 bond content = 95%, Mooney Viscosity (ML _{1 + 4} , 100 ° C.) = 45, hereinafter referred to as “butadiene rubber (B1)”)) 35 parts by mass, and styrene-butadiene rubber 65 parts by mass, carbon black “Seast KH” (Tokai 30 parts by mass of carbon (manufactured by Carbon Co., Ltd.) and 30 parts by mass of silica (manufactured by Tosoh Silica Co., Ltd., product name “Nipsil AQ”, primary average particle size 15 nm), and other additives 6 parts by mass of a silane coupling agent (product name “Si69” manufactured by Evonik), 15 parts by mass of extension oil, 5 parts by mass of zinc oxide, 2 parts by mass of stearic acid, and A.I. 1 part by mass of O6C was kneaded for 5 minutes under kneading conditions of a temperature of 90 ° C., a rotation speed of 60 rpm, and a filling rate of 70%.
Next, after the obtained kneaded product is cooled to room temperature, the kneaded product is referred to as a vulcanization accelerator “NOXERA-D” (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., hereinafter “vulcanization accelerator (1)”). ) 1.5 parts by mass, vulcanization accelerator “Noxera-CZ” (manufactured by Ouchi Shinsei Chemical Co., Ltd., hereinafter referred to as “vulcanization accelerator (2)”) 1.8 parts by mass, and sulfur 1.5 A rubber composition for a tread was produced by adding parts by mass and kneading under the same kneading conditions as above.

[Evaluation of rubber composition]
(1) Processability The obtained rubber composition is based on JIS K6300-1, using an L rotor, preheating time of 1 minute, rotor operating time of 4 minutes, temperature of 100 ° C., Mooney viscosity ( ML _{1 + 4} , 100 ° C.), and the index when the value of the rubber composition according to Comparative Example 1 was taken as 100 was determined. The results are shown in Table 1 below.

(2) Crack resistance After the obtained rubber composition is molded into a sheet by calendering, it is vulcanized at 160 ° C. for a predetermined time using a vulcanizing press machine, thereby comprising a crosslinked rubber having a thickness of 2 mm. A sheet was produced. A test piece made of an IV type dumbbell described in ASTM D638 was produced by punching the obtained sheet. At this time, a punching process was performed on the sheet so that the longitudinal direction of the dumbbell was aligned with the sheet, and a crack extending in the opposite direction was formed at the center position in the longitudinal direction of the dumbbell.
The obtained test piece was subjected to a constant elongation fatigue test under the conditions of an elongation rate of 100%, a measurement temperature of 23 ° C., and a rotation speed of 300 cpm, and the number of cycles until the test piece broke was measured. The case where the number of cycles was less than 18000 was evaluated as x, the case where it was 18000 or more and less than 20000 was evaluated as Δ, and the case where it was 20000 or more was evaluated as ○. The results are shown in Table 1 below.

(3) Wet skid resistance (0 ° C. tan δ):
After molding the obtained rubber composition, a rubber elastic body was prepared by vulcanization treatment at 160 ° C. using a vulcanizing press. The rubber elastic body according to Comparative Example 1 was measured using a dynamic spectrometer (manufactured by Rheometrics, USA) under the conditions of a tensile dynamic strain of 0.14%, an angular velocity of 100 radian per second, and a temperature of 0 ° C. The index when the value of 100 was 100 was determined. It is shown that wet skid resistance is larger and better as the index value is larger.

(4) DIN abrasion test After the obtained rubber composition was molded, a rubber elastic body was prepared by vulcanization treatment at 160 ° C. using a vulcanizing press. This rubber elastic body was subjected to a DIN abrasion test in accordance with JIS K6264, and an index when the value of the rubber elastic body according to Comparative Example 1 was set to 100 was obtained. The results are shown in Table 1 below.

(5) Low fuel consumption:
After molding the obtained rubber composition, a rubber elastic body was prepared by vulcanization treatment at 160 ° C. using a vulcanizing press. The rubber elastic body was measured using a dynamic spectrometer (manufactured by Rheometrics, USA) under the conditions of a tensile dynamic strain of 0.7%, an angular velocity of 100 radians per second, and 70 ° C. The index is expressed as an index with Comparative Example 1 being 100, and the smaller the value, the lower the low hysteresis loss characteristic and the better. The results are shown in Table 1 below.

<Example 2>
The component (B) is changed to 50 parts by mass of styrene-butadiene rubber and 50 parts by mass of isoprene rubber, and the filler is changed to 55 parts by mass of silica (product name “Nipsil AQ” manufactured by Tosoh Silica Co., Ltd.). The rubber composition for treads was the same as in Example 1 except that the amount of oil was changed to 5 parts by weight, the amount of extender oil was changed to 5 parts by weight, and the amount of zinc oxide was changed to 3 parts by weight. And the obtained rubber composition was evaluated. The results are shown in Table 1 below.

<Comparative example 1>
A rubber composition for a tread was prepared in the same manner as in Example 1 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 1 below.

<Comparative example 2>
Instead of the specific 1,2-polybutadiene (A1), 1,2-polybutadiene “RB820” having a syndiotactic structure (manufactured by JSR, 1,2 bond content = 92%, crystallinity = 25%, Melting point = 95 ° C., weight average molecular weight = 220,000, hereinafter referred to as “comparative 1,2-polybutadiene (A2)”) Except for using 10 parts by mass, rubber for treads in the same manner as in Example 1. A composition was prepared, and the obtained rubber composition was evaluated. The results are shown in Table 1 below.

<Comparative Example 3>
A rubber composition for a tread was prepared in the same manner as in Example 2 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 1 below.

<Comparative example 4>
A rubber composition for a tread was prepared in the same manner as in Example 2 except that 10 parts by mass of comparative 1,2-polybutadiene (A2) was used instead of the specific 1,2-polybutadiene (A1). The obtained rubber composition was evaluated. The results are shown in Table 1 below.

<Example 3>
A rubber composition for a base tread was produced as follows using a plastmill equipped with a temperature controller.
(A) 10 parts by weight of specific 1,2-polybutadiene (A1) as component, 100 parts by weight of natural rubber as component (B), 35 parts by weight of silica (product name “Nipsil AQ” manufactured by Tosoh Silica Co., Ltd.) As other additives, 2.8 parts by mass of a silane coupling agent (product name “Si69” manufactured by Evonik Co., Ltd.), 1.5 parts by mass of a surface crack inhibitor “Suntite R” (manufactured by Seiko Chemical Co., Ltd.), zinc oxide 3 0.5 parts by weight, 2 parts by weight of stearic acid, and A.I. 1.5 parts by mass of O6C was kneaded for 5 minutes under the kneading conditions of a temperature of 90 ° C., a rotation speed of 60 rpm, and a filling rate of 70%.
Next, after the obtained kneaded product is cooled to room temperature, 2 parts by mass of the vulcanization accelerator (1) and 1.8 parts by mass of sulfur are added to the kneaded product and kneaded under the same kneading conditions as above. Thus, a rubber composition for a base tread was produced.

[Evaluation of rubber composition]
(1) Workability and crack resistance The rubber composition obtained was evaluated for workability and crack resistance in the same manner as in Example 1. However, for the processability, an index was determined when the value of the rubber composition according to Comparative Example 5 was 100.
(2) Tensile strength (30 ° C):
It measured according to JIS K6301 and calculated | required the index | exponent when the value of the rubber composition which concerns on the comparative example 5 was set to 100. FIG. It shows that tensile strength is so large that this value is large, and it is so preferable that a numerical value is large.
The results are shown in Table 2.

<Comparative Example 5>
A rubber composition for a base tread was prepared in the same manner as in Example 3 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 2 below.

<Comparative Example 6>
A rubber composition for a base tread was prepared in the same manner as in Example 3, except that 10 parts by mass of comparative 1,2-polybutadiene (A2) was used instead of the specific 1,2-polybutadiene (A1). Then, the obtained rubber composition was evaluated. The results are shown in Table 2 below.

<Example 4>
A rubber composition for a side wall was produced as follows using a plastmill equipped with a temperature control device.
(A) 10 parts by mass of specific 1,2-polybutadiene (A1) as component, 60 parts by mass of butadiene rubber (B1) as component (B), and 40 parts by mass of natural rubber, and carbon black “Seast KH” ( 40 parts by mass of Tokai Carbon Co., Ltd.) and 10 parts by mass of extension oil, 3 parts by mass of zinc oxide, 2 parts by mass of stearic acid, and A.I. 1 part by mass of O6C was kneaded for 5 minutes under kneading conditions of a temperature of 90 ° C., a rotation speed of 60 rpm, and a filling rate of 70%.
Then, after the obtained kneaded product was cooled to room temperature, the kneaded product was added to the vulcanization accelerator “Noxeller NS-P” (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. .) 1 part by mass and 1.0 part by mass of sulfur were added and kneaded under the same kneading conditions as above to produce a rubber composition for a sidewall.

[Evaluation of rubber composition]
(1) Processability, crack resistance and fuel efficiency The obtained rubber composition was evaluated for processability, crack resistance and fuel efficiency in the same manner as in Example 1. However, for the processability and fuel efficiency, an index was determined when the value of the rubber composition according to Comparative Example 7 was set to 100.
(2) 300% tensile elastic modulus (30 ° C.):
According to JIS K6251, the 300% modulus was measured, and the index when the value of the rubber composition according to Comparative Example 7 was 100 was determined. The larger this value is, the better the tensile strength is.
The results are shown in Table 3.

<Comparative Example 7>
A rubber composition for a sidewall was prepared in the same manner as in Example 4 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 3 below.

<Comparative Example 8>
A rubber composition for a sidewall was prepared in the same manner as in Example 4 except that 10 parts by mass of comparative 1,2-polybutadiene (A2) was used instead of the specific 1,2-polybutadiene (A1). Then, the obtained rubber composition was evaluated. The results are shown in Table 3 below.

<Example 5>
A rubber composition for a cap tread was produced as follows using a plastmill equipped with a temperature controller.
(A) 10 parts by mass of specific 1,2-polybutadiene (A1) as component, 30 parts by mass of butadiene rubber (B1) as component (B), and 70 parts by mass of natural rubber, and carbon black “Seast KH” ( 60 parts by mass of Tokai Carbon Co., Ltd.) and 10 parts by mass of extension oil, 3 parts by mass of zinc oxide, 2 parts by mass of stearic acid, and A.I. 1 part by mass of O6C was kneaded for 5 minutes under kneading conditions of a temperature of 90 ° C., a rotation speed of 60 rpm, and a filling rate of 70%.
Next, after the obtained kneaded product is cooled to room temperature, 0.8 parts by mass of the vulcanization accelerator (3) and 1 part by mass of sulfur are added to the kneaded product and kneaded under the same kneading conditions as above. Thus, a rubber composition for a cap tread was produced.

[Evaluation of rubber composition]
The rubber composition obtained was evaluated in the same manner as in Example 1 for workability, crack resistance, wet skid property, and DIN abrasion test. Further, in the same manner as in Example 4, a 300% tensile elastic modulus (30 ° C.) was evaluated. However, for the workability, wet skid property, and DIN abrasion test, an index was determined when the value of the rubber composition according to Comparative Example 9 was 100. The results are shown in Table 4.

<Comparative Example 9>
A rubber composition for a cap tread was prepared in the same manner as in Example 5 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 4 below.

<Comparative Example 10>
A rubber composition for a cap tread was prepared in the same manner as in Example 5 except that 10 parts by mass of comparative 1,2-polybutadiene (A2) was used instead of the specific 1,2-polybutadiene (A1). Then, the obtained rubber composition was evaluated. The results are shown in Table 4 below.

<Example 6>
A rubber composition for cord coating was produced as follows using a plastmill equipped with a temperature controller.
(A) 10 parts by weight of specific 1,2-polybutadiene (A1) as component, 35 parts by weight of butadiene rubber (B1) as component (B), and 65 parts by weight of natural rubber, and carbon black “Seast KH” ( 60 parts by mass of Tokai Carbon Co.) and 7 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 3 parts by mass of cobalt stearate, and A.I. 2 parts by mass of O6C was kneaded for 5 minutes under kneading conditions of a temperature of 90 ° C., a rotation speed of 60 rpm, and a filling rate of 70%.
Next, after the obtained kneaded product is cooled to room temperature, 0.8 parts by mass of the vulcanization accelerator (3) and 1.5 parts by mass of sulfur are added to the kneaded product, and the same kneading conditions as above are used. By kneading, a rubber composition for cord coating was produced.

[Evaluation of rubber composition]
The obtained rubber composition was evaluated for workability and crack resistance in the same manner as in Example 1. Further, the tensile strength (30 ° C.) was evaluated in the same manner as in Example 3, and the 300% tensile modulus (30 ° C.) was evaluated in the same manner as in Example 4. However, for the workability, tensile strength (30 ° C.), and 300% tensile elastic modulus (30 ° C.), the index when the value of the rubber composition according to Comparative Example 11 was 100 was determined. Furthermore, the adhesiveness with the metal was evaluated as follows.
Adhesion with metal:
This was performed in accordance with JIS K6301. A strip-shaped sample was prepared by embedding a steel cord having a cord diameter of 1.2 mm and a twisted structure 3 + 6 in a rubber composition so that the number of punches was 26/5 cm, and vulcanized at 145 ° C. for 40 minutes to obtain a test piece. did. The test piece was cut with a knife and peeled off at room temperature so that the rubber did not tear at a speed of 25 mm / min. The peeled surface was visually observed, and the rubber adhered to the peeled cord surface. The state was indexed. The state of complete adhesion is 100, and the larger the index, the better the adhesion interface state. The results are shown in Table 5.

<Comparative Example 11>
A rubber composition for cord coating was prepared in the same manner as in Example 6 except that the specific 1,2-polybutadiene (A1) was not used, and the obtained rubber composition was evaluated. The results are shown in Table 5 below.

<Comparative example 12>
A rubber composition for cord coating was prepared in the same manner as in Example 6 except that 10 parts by mass of comparative 1,2-polybutadiene (A2) was used in place of the specific 1,2-polybutadiene (A1). Then, the obtained rubber composition was evaluated. The results are shown in Table 5 below.

<Example 7>
A rubber composition for a tire case was produced as follows using a plastmill equipped with a temperature control device.
20 parts by weight of specific 1,2-polybutadiene (A1) as component (A), 80 parts by weight of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) as component (C), and magnesium sulfate as other additive A rubber composition for a tire case was manufactured by kneading 1 part by weight of whisker under a kneading condition of a temperature of 180 ° C., a rotation speed of 60 rpm, and a filling rate of 70% for 5 minutes.

[Evaluation of rubber composition]
About the obtained rubber composition, processability was evaluated in the same manner as in Example 1.
Moreover, the sheet | seat with a thickness of 2 mm was produced by shape | molding the obtained rubber composition into a sheet form by the calendar process. This sheet was evaluated for crack resistance under the same conditions as in Example 1.
The obtained rubber composition was molded, and the obtained molded product was evaluated for low fuel consumption under the same conditions as in Example 1.
Further, the obtained rubber composition was molded, and the obtained molded product was subjected to tensile strength (30 ° C.) under the same conditions as in Example 3 and 300% tensile elastic modulus (30 under the same conditions as in Example 4). The tensile strength (80 ° C.) and 300% tensile elastic modulus (80 ° C.) were similarly evaluated except that the test temperature was changed from 30 ° C. to 80 ° C.
However, the processability, fuel efficiency, tensile strength (30 ° C.), 300% tensile elastic modulus (30 ° C.), tensile strength (80 ° C.) and 300% tensile elastic modulus (80 ° C.) are related to Comparative Example 13. The index when the value of the rubber composition was 100 was determined.
The results are shown in Table 6.

<Comparative Example 13>
Tire case in the same manner as in Example 7 except that the specific 1,2-polybutadiene (A1) was not used and the amount of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) was changed to 100 parts by mass. A rubber composition was prepared, and the obtained rubber composition was evaluated. The results are shown in Table 6 below.

<Comparative example 14>
A rubber composition for a tire case was prepared in the same manner as in Example 7 except that 20 parts by mass of comparative 1,2-polybutadiene (A2) was used instead of the specific 1,2-polybutadiene (A1). Then, the obtained rubber composition was evaluated. The results are shown in Table 6 below.

  As is clear from the results of Tables 1 to 6, according to the compositions according to Examples 1 to 7, a rubber elastic body having excellent crack resistance is obtained, and good workability is obtained. It was confirmed that the characteristics according to the application can be obtained.

Claims (3)

  A component (A) made of 1,2-polybutadiene having a 1,2 bond content of 90% or more and a melting point of 100 ° C. or more, and a vulcanizable rubber other than this component (A) (B) A rubber composition comprising: a component.   It is selected from (A) component consisting of 1,2-polybutadiene having a 1,2 bond content of 90% or more and a melting point of 100 ° C. or more, and a thermoplastic resin and a thermoplastic elastomer other than this (A) component. A rubber composition comprising at least one component (C).   A component (A) made of 1,2-polybutadiene having a 1,2 bond content of 90% or more and a melting point of 100 ° C. or more, and a vulcanizable rubber other than this component (A) (B) A rubber composition comprising: a component; and a component (C) composed of at least one selected from a thermoplastic resin and a thermoplastic elastomer other than the component (A).