JP2014136759A - Rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition excellent in grip resistance.SOLUTION: There is provided a rubber composition containing 100 pts.wt. of a styrene-butadiene copolymer having cis-1,4 bond of a micro structure of the butadiene unit of 40 wt.% or more as a rubber composition and 0.5 to 70 pts.wt. of isobutylene polymer having an isobutylene unit of 100 to 90 wt.% and an isoprene binding unit of the formula (2) of 0 to 10 wt.%. The weight average molecular weight (Mw) of the isobutylene polymer is 5,000 to 100,000, the molecular distribution (Mw/Mn) is 3.0 or less, and the content of styrene-butadiene is 70 wt.% or more.

Description

  The present invention relates to a rubber composition excellent in grip properties when applied to a tire, and a rubber excellent in grip properties when applied to a tire formed by crosslinking the rubber composition.

  Crosslinked products of diene rubbers such as styrene butadiene copolymer rubber (SBR) are excellent in grip characteristics, and are used, for example, in the tread portion in contact with the road surface of the tire, due to olefin bonds in the main chain. , Heat resistance, weather resistance, ozone degradation resistance, etc. may be a problem. On the other hand, α-olefin-nonconjugated diene copolymer rubbers such as butyl rubber (IIR) containing a small amount of olefin bond in the main chain and EPDM containing olefin bond only in the side chain have good heat resistance and weather resistance. is there.

Therefore, in order to improve the properties of diene rubber while maintaining the grip properties, butyl rubber (IIR) containing a small amount of olefin bonds in the main chain and α-olefin-nonconjugated diene copolymer containing olefin bonds only in the side chain Rubber compositions and their cross-linked rubbers have been studied, and proposals have been made mainly for SBR / IIR and SBR / EPDM systems. Rubbers with a main chain structure typified by butyl rubber are grasped by changes in tan δ. The improvement effect of grip performance (also referred to as tread characteristics) of diene rubber has been recognized. However, in recent years, when the molecular structure of diene rubber is precisely controlled and rubbers with various chemical structures are provided, the individual additivity of each rubber may not be easily established in blend rubber properties. It has been confirmed. This is thought to be due to the morphology before crosslinking that appears based on the compatibility between the two rubbers and the difference in the crosslinking speed between the two rubbers.
The patent documents shown below include modification of halogenated rubber to diene rubber (Patent Document 1), modification of butyl rubber to diene rubber by addition of pentaerythritol and the like (Patent Document 2), modification of diene rubber. Effective as a quality agent, rubber having an olefin structure only in the side chain (Patent Document 3), modification of butyl rubber to a diene rubber by addition of a mineral mainly composed of sepiolite (Patent Document 4), EPDM and the like Modification of butyl rubber to diene rubber by using a phosphorus vulcanization accelerator (Patent Document 5), modification of modified butyl rubber to diene rubber by addition of a specific chemical substance (Patent Document 6), and the like are disclosed. However, there has been no report regarding improvement of tire grip properties by adding an isobutylene polymer or butyl rubber to a diene rubber such as SBR.

Japanese Patent Laid-Open No. 5-1177 JP-A-6-116443 International Patent Publication No. 2011/021437 JP-A-11-246707 JP 11-227409 A JP 2012-167240 A

  In order to further improve the grip performance of the diene rubber, the present inventors selected SBR as the diene rubber and a rubber having an isobutylene main chain structure typified by butyl rubber as the modifier, and the molecular structure between them, By specifying the molecular weight relationship, it was found that a rubber having a particularly high grip performance was obtained, and the present invention was completed.

In the first aspect of the present invention, the rubber component is a styrene-butadiene copolymer, and the cis-1,4 bond in the microstructure of the butadiene unit is 40% by weight or more with respect to 100 parts by weight of the styrene-butadiene copolymer. The isobutylene-based polymer having a structural unit represented by the following formula (1) 100 to 90% by weight and the following formula (2) 0 to 10% by weight (both are 100% by weight). The present invention relates to a rubber composition containing 70 parts by weight.

  The second of the present invention is characterized in that the isobutylene polymer has a weight average molecular weight (Mw) of 5,000 to 100,000 and a molecular weight distribution dispersity (Mw / Mn) of 3.0 or less. The present invention relates to a first rubber composition of the present invention.

  A third aspect of the present invention relates to the first or second rubber composition of the present invention, wherein the styrene-butadiene copolymer rubber has a butadiene content of 70% by weight or more.

A fourth aspect of the present invention relates to the rubber composition according to any one of the first to third aspects of the present invention, wherein the Mooney viscosity (ML _{1 + 4} , 100 ° C.) is 30 to 50.

  A fifth aspect of the present invention relates to a rubber obtained by crosslinking the rubber composition according to any one of the first to fourth aspects of the present invention.

  A sixth aspect of the present invention relates to a tire characterized by comprising the fifth rubber of the present invention as a constituent material.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition excellent in grip property, when it applies to a tire which uses highly reliable SBR as a tire material as a main raw material can be obtained.

  In the present invention, a solution-polymerized styrene butadiene copolymer having a cis-1,4 bond content of the butadiene unit of the diene polymer of 40% by weight or more is used. These copolymers are described as S-SBR and are commercially available. For example, “Toughden” manufactured by Asahi Kasei Chemicals Corporation can be raised. In principle, the microstructure of butadiene includes a cis-1,4 bond, a trans-1,4 bond, and a 1,2-bond. In the present invention, the cis of the butadiene unit is analyzed by the following analysis method. -1,4 bond content determined to be 40% by weight or more. The content of cis-1,4 bonds in ordinary styrene butadiene is less than 35% by weight according to this analysis method.

In the present invention, the ratio of cis-1,4 bonds in the styrene-butadiene copolymer is carried out in accordance with JIS K6239 “How to Determine the Microstructure of Raw Rubber-Solution Polymerized SBR (Quantitative)”. The extracted SBR sample is subjected to ¹ H-NMR measurement and IR measurement to calculate the cis-1,4 unit, trans-1,4 unit, 1,2 unit, and styrene content of the butadiene unit in the SBR. did. These analysis results were shown in the Example mentioned later.

  As the content of the cis-1,4 structure increases, an increase in the crosslinking rate and an improvement in the properties of high grip properties are expected, but on the other hand, the compatibility with other rubber components also changes. A rubber having an isobutylene main chain structure represented by butyl rubber which has excellent compatibility or so-called microphase separation in response to this change has not been known.

および、必要に応じて、下記式（２）：

からなり、式（１）が１００〜９０重量％、式（２）が０〜１０重量％の割合（両者合わせて１００重量％とする。）のイソブチレン系重合体を用いる。 In the present invention, as a modifier of S-SBR, the main chain structure has the following formula (1):

And, if necessary, the following formula (2):

An isobutylene polymer having a ratio of 100 to 90% by weight of formula (1) and 0 to 10% by weight of formula (2) (both are 100% by weight in total) is used.

  The present inventors consider that these isobutylene polymers are excellent in compatibility with S-SBR and constitute so-called microphase separation, judging from the results of Examples described later. That is, by constituting this microphase separation, the total interface area with the isobutylene polymer finely dispersed in S-SBR is increased, and in the blend system, the formulas (1) and (2 ), The viscoelastic characteristics of the structure represented mainly by the formula (1) are efficiently transmitted to S-SBR, and it is considered that the grip performance when applied to a tire is improved.

  In order to express the above effect, first, it is preferable to use S-SBR as a continuous phase (or matrix) and an isobutylene-based polymer as a dispersed phase (or domain). The isobutylene polymer is 0.5 to 70 parts by weight with respect to 100 parts by weight of S-SBR. If the amount is 0.5 parts by weight or less, the effect of modifying the isobutylene polymer cannot be sufficiently obtained. If the amount exceeds 70 parts by weight, the phase structure tends to become unstable.

  The improvement in the grip performance according to the present invention mainly depends on the structure represented by the formula (1) in the isobutylene polymer, so the ratio of the structure represented by the formula (2) is the isobutylene type. The content is preferably 10% by weight or less based on the total weight of the polymer.

  In addition, in order to use S-SBR as a continuous phase and an isobutylene polymer as a dispersed phase, the molecular weight (Mw) of the isobutylene polymer is reduced, and the degree of dispersion of the molecular weight distribution, in addition to the adjustment of the blending ratio described above. It is also preferable to reduce (Mw / Mn). Specifically, it is preferable that the weight average molecular weight (Mw) is 5,000 to 100,000 and the dispersity (Mw / Mn) is 3.0 or less.

  Also, in order to use S-SBR as a continuous phase and an isobutylene polymer as a dispersed phase, butadiene having a cis-1,4 bond structure in S-SBR, which is considered highly compatible with the isobutylene polymer. It is preferable to increase the unit weight as much as possible, and the butadiene content in S-SBR is preferably 70% by weight or more.

Among the isobutylene polymers according to the present invention, those having substantially only the structure represented by the formula (1) can be obtained from the market. An example is “Tetrax 3T (trade name)” manufactured by JX Nippon Oil & Energy Corporation.
Moreover, among the isobutylene polymers according to the present invention, those containing 10% or less of the formula (2) can also be obtained from the market. An example is “BUTYL 268” manufactured by JSR Corporation (the content of the structure of formula (2) is 1.8% by weight).

  In the present invention, a diene rubber other than S-SBR may be included as a rubber component. For example, a styrene butadiene copolymer having a cis-1,4 bond content of butadiene units of less than 35% by weight, natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), and nitrile butadiene rubber (NBR). And chloroloprene rubber (CR). These may use only 1 type and can also use 2 or more types together.

  In the present invention, in addition to the isobutylene polymer according to the present invention, an α-olefin-nonconjugated diene compound copolymer rubber other than the α-olefin-nonconjugated diene compound copolymer rubber may be included. For example, EPDM using 1,6-hexadiene, dicyclopentadiene, ethylidene norbornene, or the like. These may use only 1 type and can also use 2 or more types together.

  In the rubber composition according to the present invention, the above-mentioned isobutylene polymer, an additive such as a softener / plasticizer, an antioxidant, an ultraviolet absorber, an anti-aging agent, a reinforcing material such as carbon black, and the like, a normal rubber A chemical used in processing is blended to perform crosslinking.

In the case of performing crosslinking of a diene rubber other than normal peroxide crosslinking, when the isobutylene polymer in the present invention substantially contains only the formula (1) as a repeating unit, it is substantially crosslinked. Absent. Even in the final rubber, it is considered to function as an uncrosslinked dispersed phase.
When the structure represented by the formula (2) is substantially contained by 10% by weight or less, the cross-linking of the isobutylene polymer itself and the co-crosslinking of S-SBR and the isobutylene polymer proceed, and the compatibility between the two. Will be further improved.
Among the crosslinking reactions, preferable ones are sulfur-based crosslinking from the viewpoint of grip characteristics when applied to a tire.

  Even in the case of having only the structure represented by the formula (1), peroxide crosslinking is carried out when the cross-linking of the isobutylene polymer itself and the co-crosslinking of both including S-SBR are advanced. Is preferred. In this case, since formula (1) causes molecular chain scission, when it is desired to suppress this, it is preferable to use a highly reactive crosslinking agent such as divinylbenzene or m-phenylenebismaleimide.

The Mooney viscosity of the rubber composition before crosslinking is not limited, but the Mooney viscosity (ML _{1 + 4} , 100 ° C.) is preferably 30-50. Outside these ranges, the torque in kneading becomes excessive and insufficient, and the dispersion structure is not sufficiently secured and the dispersion / diffusion of various additives, etc., is insufficient, and the effects of the present invention may not be sufficiently obtained.

  Examples of the reinforcing agent include carbon black and silica.

  Carbon black is suitably used as a reinforcing agent from the viewpoints of improving wear resistance, improving rolling resistance characteristics, preventing cracks and cracks caused by ultraviolet rays (preventing ultraviolet degradation), and the like. The type of carbon black is not particularly limited, and conventionally known carbon blacks such as furnace black, acetylene black, thermal black, channel black, and graphite can be used. Further, the physical characteristics such as particle size, pore volume and specific surface area of carbon black are not particularly limited, and various carbon blacks conventionally used in the rubber industry, for example, SAF, ISAF, HAF, FEF, GPF, SRF (all are abbreviations of carbon black classified according to the US ASTM standard D-1765-82a) and the like can be used as appropriate. When carbon black is used, the blending amount is preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A). Moreover, it can also be set as 30-80 mass parts, and can also be set as 40-60 mass parts. In such a blending amount, the effect as a reinforcing agent can be favorably obtained in the rubber composition and the crosslinked rubber composition according to the present embodiment.

As silica, those conventionally used as rubber reinforcing agents can be used without particular limitation, such as dry method white carbon, wet method white carbon, synthetic silicate white carbon, colloidal silica, precipitated silica and the like. It is done. The specific surface area of silica is not particularly limited, but usually a silica having a surface area of 40 to 600 m ² / g, preferably 70 to 300 m ² / g, and a primary particle diameter of 10 to 1000 nm should be used. Can do. These may be used alone or in combination of two or more. The amount of silica used is preferably 0.1 to 150 parts by mass, more preferably 10 to 100 parts by mass, and 30 to 100 parts by mass with respect to 100 parts by mass of the rubber component (A). Is more preferable.

  Moreover, you may mix | blend a silane coupling agent with a rubber composition in order to mix | blend a silica. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4-epoxycyclohexyl) -ethyltrimethoxysilane, and 3-chloropropyltrimethoxy. Silane, 3-chloropropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, bis (3- (triethoxysilyl) propyl) tetrasulfide, bis (3- (triethoxysilyl) propyl ) Disulfide and the like. These may be used alone or in combination of two or more. Although the addition amount of a silane coupling agent can be suitably changed with the compounding quantity of the desired silica, it is preferable that it is 0.1-20 mass parts with respect to 100 mass parts of rubber components (A).

  As the filler, mineral powders such as clay and talc, carbonates such as magnesium carbonate and calcium carbonate, alumina hydrate such as aluminum hydroxide, and the like can be used.

  As softeners and plasticizers, plant oil softeners such as tall oil, mainly linoleic acid, oleic acid, and abithienic acid, pineapple, rapeseed oil, cottonseed oil, peanut oil, castor oil, palm oil, fuacitis, paraffinic oil, Examples thereof include naphthenic oils, aromatic oils, and phthalic acid derivatives such as dibutyl phthalate. It is preferable that the compounding quantity of a softener is 0-50 mass parts with respect to 100 mass parts of rubber components (A).

  The rubber composition according to this embodiment also includes various additives used in the field of the rubber industry, such as anti-aging agents, sulfur, crosslinking agents, vulcanization accelerators, vulcanization retarders, peptizers, processes. You may contain 1 type, or 2 or more types, such as oil and a plasticizer, as needed. It is preferable that the compounding quantity of these additives is 0.1-10 mass parts with respect to 100 mass parts of rubber components (A).

  Antiaging agents include primary amines such as p, p′-diaminodiphenylmethane; secondary amines such as phenyl-α-naphthylamine and N, N′-diphenyl-p-phenylenediamine; 2,6-di Examples include alkylphenols such as tert-butyl-p-cresol, 2,5-ditert-butyl-hydroquinone and hydroquinone monobenzyl ether; and imidazoles such as 2-mercaptobenzimidazole. It is preferable that a compounding quantity is 0.1-10 mass parts with respect to 100 mass parts of rubber components (A).

  Examples of the vulcanization accelerator include thiuram accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetraethylthiuram disulfide; thiazole accelerators such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide; N-cyclohexyl Sulfenamide accelerators such as 2-benzothiazylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide; guanidine accelerators such as diphenylguanidine and diortolylguanidine; n-butyraldehyde -Aldehyde-amine accelerators such as aniline condensates and butyraldehyde-monobutylamine condensates; aldehyde-ammonia accelerators such as hexamethylenetetramine; thiourea accelerators such as thiocarbanilide Agents, and the like. When blending these vulcanization accelerators, one type may be used alone, or two or more types may be used in combination. It is preferable that content of a vulcanization accelerator is 0.1-10 mass parts with respect to 100 mass parts of rubber components (A).

  Vulcanization aids include metal oxides such as zinc oxide (zinc white) and magnesium oxide; metal hydroxides such as calcium hydroxide; metal carbonates such as zinc carbonate and basic zinc carbonate; stearic acid and oleic acid Aliphatic acid salts such as zinc stearate and magnesium stearate; amines such as di-n-butylamine and dicyclohexylamine; ethylene dimethacrylate, diallyl phthalate, N, Nm-phenylene bismaleimide, triallyl isocyanurate And trimethylolpropane trimethacrylate. When blending these vulcanization aids, one type may be used alone, or two or more types may be used in combination. The content of the vulcanization aid is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component (A).

The rubber composition according to the present embodiment can be produced by applying a method generally used as a method for producing a rubber composition. For example, it can manufacture by mixing each component mentioned above using kneading machines, such as a Brabender, a Banbury mixer, and a roll mixer.
The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples.

[Example 1]
As styrene-butadiene copolymer rubber (hereinafter abbreviated as SBR), solution-polymerized styrene-butadiene rubber, trade name “Tuffden 1000” (manufactured by Asahi Kasei Chemicals Co., Ltd.), and polyisobutylene polymer as polyisobutylene, trade name “Tetrax 3T” (manufactured by JX Nippon Oil & Energy Corporation, Mw 32,000, Mw / Mn 2.0) was used.
A filler, a plasticizer, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, and an anti-aging agent are blended in the amounts shown in Table 1 in 100 parts by weight of the above SBR and 10 parts by weight of polyisobutylene, respectively. 6 inch φ × 16 inch) and kneading under the conditions of a rotation speed of 30 rpm and a front-rear roll rotation ratio of 1: 1.22 to obtain a rubber composition having a predetermined Mooney viscosity.
Silica AQ (manufactured by Tosoh Silica) is used as the filler, process oil “NS-100” (manufactured by Idemitsu Kosan Co., Ltd.) as the plasticizer, and sulfur (Kawagoe Chemical Co., Ltd.) as the vulcanizing agent. Made of Zinc Oxide No. 3 (Hakusui Tech Co., Ltd.) and stearic acid (made by Nippon Seika Co., Ltd.) as vulcanization aids, and sulfenamide accelerators as vulcanization accelerators. “Noxeller CZ (N-cyclohexyl-2-benzothiazylsulfenamide)” (manufactured by Ouchi Shinsei Chemical Co., Ltd.) and the guanidine accelerator “Noxeller D (1,3-diphenylguanidine)” (Emerging Ouchi) Chemical Co., Ltd.) and “Aging Prevention Agent 224” (manufactured by Ouchi Shinsei Chemical Co., Ltd.) were used as anti-aging agents.
The rubber composition after kneading was compression molded under a vulcanization condition of 160 ° C. × 20 minutes to produce a sheet. Vulcanization characteristics and dynamic viscoelasticity (that is, an index of grip resistance) at the time of producing the sheet were evaluated. These results are shown in Table 3.

[Example 2]
The same procedure as in Example 1 was performed except that 100 parts by weight of solution-polymerized styrene-butadiene rubber, trade name “Tuffden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) was used as SBR.

[Example 3]
As SBR, 70 parts by weight of solution-polymerized styrene-butadiene rubber, trade name “Tuffden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) is used, and butadiene rubber (BR) (trade name “BR1220”, produced by Nippon Zeon Co., Ltd.). ) It carried out like Example 1 except having added 30 weight part and mix | blending.

The polyisobutylene used in Example 4 was prepared as follows.
[Synthesis of polyisobutylene]
Attach a septum cap, a reflux tube connected to a vacuum line, and a temperature tube to a 300 mL 3-neck flask, put a stirrer bar, and repeat degassing-nitrogen replacement in the system twice using a vacuum line (with a Schlenk tube). And under a normal pressure nitrogen atmosphere. Into the flask, 100 mL of a toluene solvent dried and distilled with calcium hydride was injected from a septum cap using a syringe.
Next, the flask was immersed in a low temperature bath at a predetermined temperature, and after confirming that the liquid temperature in the system reached 10 ° C., 30 g of isobutylene was transferred to the reaction system. When it was confirmed that the liquid temperature in the system was stable at 10 ° C., a 0.1 mol / L ethylaluminum dichloride (EADC) / n-hexane solution in a glove box under a nitrogen atmosphere was isobutylene / EADC = 60. It was weighed with a syringe so as to be 1,000 (molar ratio) and injected into the reactor.
Two hours after the injection of the catalyst solution, the low-temperature bath was removed from the flask and allowed to stand at room temperature. The reaction mixture was extracted with a 1N aqueous sodium hydroxide solution (twice), and the resulting oil phase was extracted with pure water. After confirming that the pH of the aqueous phase became neutral, the solvent was distilled off from the oil phase with an evaporator, and the residue was dried with a vacuum dryer at 1 mmHg for 12 hours at 60 ° C. 21 g of polyisobutylene was obtained.
The polyisobutylene (synthetic product) used in Example 5, Comparative Example 5, Comparative Example 6, and Comparative Example 7 was synthesized in the same manner as above except that the catalyst concentration and the reaction temperature were changed.

[Example 4]
As SBR, 100 parts by weight of solution-polymerized styrene-butadiene rubber, trade name “Tuffden 2000R” (manufactured by Asahi Kasei Chemicals Co., Ltd.) was used, and Mw11,000 and Mw / Mn2.6 polyisobutylene (in the above synthesis method) Preparation) was carried out in the same manner as in Example 1, except that 10 parts by weight were used.

[Example 5]
As SBR, 100 parts by weight of solution-polymerized styrene-butadiene rubber, trade name “Toughden 2000R” (manufactured by Asahi Kasei Chemicals Corporation), and polyisobutylene (synthetic product) of Mw 97,000 and Mw / Mn 1.9 as additives are used. It implemented like Example 1 except having used 10 weight part.

[Example 6]
As SBR, 70 parts by weight of solution-polymerized styrene-butadiene rubber, trade name “Tuffden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) and butyl rubber as an additive, trade name “BUTYL 268” (manufactured by JSR Corporation): ( Example 2 was carried out in the same manner as in Example 1 except that 30 parts by weight of the content of 1.8% by weight was used.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that solution-polymerized styrene-butadiene rubber, “SL-552 (manufactured by JSR Corporation)” was used as SBR.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that solution-polymerized styrene-butadiene rubber, “SL-563 (manufactured by JSR Corporation)” was used as SBR.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that solution-polymerized styrene-butadiene rubber, “NS116R (manufactured by Nippon Zeon Co., Ltd.)” was used as SBR.

[Comparative Example 4]
The SBR was carried out in the same manner as in Example 1 except that “Tuffden 2003 (manufactured by Asahi Kasei Chemicals Corporation)” was used as the solution-polymerized styrene-butadiene rubber.

[Comparative Example 5]
As SBR, solution polymerized styrene-butadiene rubber, trade name “Toughden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) was used, and polyisobutylene (synthetic product) of Mw 3,800 and Mw / Mn 2.9 was used as an additive. Except for this, the same procedure as in Example 1 was performed.

[Comparative Example 6]
As SBR, solution polymerized styrene-butadiene rubber, trade name “Toughden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) was used, and polyisobutylene (synthetic product) of Mw 33,000 and Mw / Mn 3.8 was used as an additive. Except for this, the same procedure as in Example 1 was performed.

[Comparative Example 7]
As SBR, solution-polymerized styrene-butadiene rubber, trade name “Tuffden 2000R” (manufactured by Asahi Kasei Chemicals Corporation) was used, and polyisobutylene (synthetic product) of Mw 205,000 and Mw / Mn 2.8 was used as an additive. Except for this, the same procedure as in Example 1 was performed.

[Measurement of Mooney viscosity]
The Mooney viscosity was measured according to JIS K 6300-1: 2001 “Unvulcanized rubber—physical properties—Part 1: Determination of viscosity and scorch time using Mooney viscometer”. Table 3 shows the measurement results.

[Measurement of vulcanization speed]
The measurement of the vulcanization speed was carried out according to JIS K 6300-2: 2001 “Unvulcanized rubber—Physical characteristics—Part 2: Determination of vulcanization characteristics using a vibration vulcanization tester”. Table 3 shows the measurement results, with the time until the vulcanization degree reaches 90% (T90, minutes) as the vulcanization rate.

[Measurement of dynamic viscoelasticity]
The measurement of dynamic viscoelasticity was performed according to JIS K 7244-4: 1999 “Plastics—Testing method of dynamic mechanical properties—Part 4: Tensile vibration—Non-resonance method”. Specifically, from a sheet obtained in Examples 1 and 2 and Comparative Examples 1 to 5, one test piece having a thickness of 1 mm, a width of 5 mm, and a length of 40 mm was cut out and used, with a frequency of 10 Hz and a dynamic strain of 0. Under the condition of 0.1%, the temperature was measured in the tensile mode while increasing the temperature in the range of −50 to 100 ° C. at 2 ° C./min. The apparatus used is a dynamic viscoelasticity measuring apparatus RSA-3 (manufactured by TA INSTRUMENTS). When the time conversion side of viscoelasticity is used, the wet grip property correlates with a loss coefficient (tan δ) value at 10 Hz-0 ° C., and the wet grip property (brake braking property) is better as the value is larger. It is known. Table 3 shows the measurement results.

  Examples 1-6 have a large 0 ° C. tan δ value (good grip properties). In addition, the vulcanization speed is fast and the productivity is excellent.

The rubber composition of the present invention can be particularly suitably used for tire applications. For example, automobile tires and tubes, inner liners, bead fillers, plies, belts, tread rubbers, side rubbers, various sealing materials, sealants, and aircraft use It can be used for applications such as tires and tubes, bicycle tires and tubes, solid tires, and corrected tires.
In addition to tire applications, it can be used for applications such as shoe soles, grips for golf and tennis clubs, golf balls, tennis balls, and the like.

  The rubber composition according to the present invention can achieve both improvement in productivity and increase in grip properties due to an increase in the crosslinking speed, and can be suitably used particularly for tire tread applications. It has the possibility of being used for applications such as a club grip such as tennis, a golf ball, and a tennis ball.

Claims (6)

The rubber component is a styrene-butadiene copolymer, and 100 parts by weight of the styrene-butadiene copolymer in which the cis-1,4 bond of the microstructure of the butadiene unit is 40% by weight or more,
0.5 to 70 weight percent of an isobutylene polymer having a structural unit represented by the following formula (1) 100 to 90 weight percent and the following formula (2) 0 to 10 weight percent (both are 100 weight percent). A rubber composition comprising parts.

  The isobutylene polymer has a weight average molecular weight (Mw) of 5,000 to 100,000 and a molecular weight distribution dispersity (Mw / Mn) of 3.0 or less. Rubber composition.   3. The rubber composition according to claim 1, wherein the styrene content of the styrene-butadiene copolymer rubber is 70% by weight or more. _4. The rubber composition according to claim 1, wherein the Mooney viscosity (ML _{1 + 4} , 100 ° C.) is 30 to 50. 5.   A rubber obtained by crosslinking the rubber composition according to any one of claims 1 to 4.   A tire comprising the rubber according to claim 5 as a constituent material.