JP2014189698A - Rubber composition for tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire tread having improved steering stability, dry performance and wet performance compared to conventional compositions.SOLUTION: There is provided a rubber composition manufactured by blending 100 pts.wt. of a rubber composition having total 100 wt.% of 5 to 30 wt.% of an elastomer to which a styrene-diene-styrene copolymer partially hydrogenated and 95 to 70 wt.% of a diene-based rubber 1, 80 to 160 pts.wt. of an inorganic filler and 2 to 30 pts.wt. of an aromatic modified terpene resin, and 95 to 40 wt.% of the diene-based rubber 1 is a styrene butadiene rubber SBR1 having the glass transition temperature of -30°C to -5°C and the inorganic filler consisting of 40 to 90 pts.wt. of silica and 40 to 80 pts.wt. of carbon black having a nitrogen adsorption specific surface area of 90 to 200 m/g.

Description

  The present invention relates to a rubber composition for a tire tread, and more particularly to a rubber composition for a tire tread in which handling stability, dry performance, and wet performance are improved to a level higher than conventional levels.

  The performance required for pneumatic tires for racing cars and high-performance cars is diverse, especially in terms of handling stability at high speeds, and stability on dry and wet road surfaces (dry and wet performance). In addition, it is required to suppress changes in tire performance (abrasion skin and thermal sag) when running at high speed on an autobahn or circuit for a long time. For example, even when the traveling road surface changes from a wet state to a semi-wet state every time, such as a circuit when it rains, high speed traveling performance and grip performance are required to be continuously excellent.

  Patent Document 1 discloses a styrene-butadiene copolymer rubber (SBR) having a glass transition temperature (Tg) of −30 ° C. to 0 ° C. in order to improve grip performance maintenance when changing from a wet state to a semi-wet state and further to a dry state. ) Alone or a mixture of two or more types of SBR with an average Tg of −30 ° C. to 0 ° C. and 100 parts by weight of SBR, 80 to 180 parts by weight of a filler containing 50 parts by weight or more of silica, 100 to 150 ° C. The rubber composition which mix | blended 5-60 weight part of resin which has the softening point of this is proposed. However, the rubber composition described in Patent Document 1 is not always sufficient to fully meet the demands of consumers for handling stability at high speeds, its sustainability, dry performance, and wet performance.

JP 2007-321046 A

  An object of the present invention is to provide a rubber composition for a tire tread in which handling stability, dry performance, and wet performance are improved to the conventional level or more.

The rubber composition for a tire tread of the present invention that achieves the above object comprises 5-30% by weight of an elastomer partially hydrogenated with a styrene-diene-styrene copolymer and 95-70% by weight of a diene rubber 1. A rubber composition in which 80 to 160 parts by weight of an inorganic filler and 2 to 30 parts by weight of an aromatic modified terpene resin are blended with 100 parts by weight of a rubber component that is 100% by weight in total, the diene rubber 1 Among them, the styrene-butadiene rubber SBR1 having a glass transition temperature of −30 ° C. to −5 ° C. is 95 to 40% by weight, the inorganic filler is 40 to 90 parts by weight of silica, and the nitrogen adsorption specific surface area is 90 to 90%. 200 to 80 parts by weight of carbon black of 200 m ² / g

The rubber composition for a tire tread of the present invention comprises 5-30% by weight of an elastomer partially hydrogenated with a styrene-diene-styrene copolymer, and a styrene butadiene having a glass transition temperature of -30 ° C to -5 ° C. 100 parts by weight of a rubber component which is 95% to 70% by weight in total of 95 to 70% by weight of diene rubber 1 containing 95 to 40% by weight of rubber SBR1, 2 to 30 parts by weight of aromatic modified terpene resin, and silica 40 to 90 parts by weight and 80 to 160 parts by weight of an inorganic filler composed of 40 to 80 parts by weight of carbon black having a nitrogen adsorption specific surface area of 90 to 200 m ² / g are combined to improve steering stability, dry performance and wetness. The performance can be improved beyond the conventional level.

  As the elastomer, an elastomer obtained by partially hydrogenating a styrene-butadiene-styrene copolymer is preferable.

As a rubber composition for a tire tread for a racing car, the styrene butadiene rubber SBR1 is a solution-polymerized styrene butadiene rubber S having a glass transition temperature of -30 ° C to -5 ° C and a weight average molecular weight of 1,000,000 to 1,800,000. an SBR, the S-SBR with content of the rubber component 100 wt% 95 to 60 wt% of a nitrogen adsorption specific surface area of the carbon black is 130~200m ² / g, the aromatic modified terpene The amount of resin is preferably 10 parts by weight or less, and can be suitably used for competition and commercial wet tires and wet-dry combined grooved tires.

As a rubber composition for tire treads for high performance automobiles traveling on public roads, the diene rubber 1 is a styrene butadiene rubber SBR2 having a glass transition temperature of -30 ° C to -15 ° C and a glass transition temperature of -50 ° C. It is composed of the following diene rubber 2, and the content of the styrene butadiene rubber SBR2 is 85 to 40% by weight in 100% by weight of the rubber component, and the nitrogen adsorption specific surface area of the carbon black is 90 to 130 m ² / g. It is preferable that

  A pneumatic tire using the above-described rubber composition in the tread portion can improve steering stability, dry performance, and wet performance to a level higher than the conventional level.

  In the rubber composition for a tire tread of the present invention, the rubber component comprises an elastomer partially hydrogenated with a styrene-diene-styrene copolymer (hereinafter referred to as “partially hydrogenated elastomer”) and a diene rubber 1. The total of these is 100% by weight.

  The partially hydrogenated elastomer is an elastomer obtained by partially hydrogenating a styrene-diene-styrene copolymer such as styrene-butadiene-styrene or styrene-isoprene-styrene. By partially hydrogenating the polydiene block of styrene-diene-styrene copolymer, the wet performance (tan δ at 0 ° C) is improved by the vulcanizable segment, and the rubber hardness and elastic modulus at high temperature , Rubber strength can be improved. As a result, it is possible to improve the dry grip performance and the handling stability over the conventional level while improving the wet grip performance. On the other hand, a rubber composition containing an elastomer such as styrene-ethylene / butylene-styrene copolymer (SEBS) and styrene-ethylene / propylene-styrene (SEPS) completely hydrogenated with styrene-diene-styrene copolymer is Since there is no vulcanizable segment, the wet performance (tan δ at 0 ° C.), dry performance (tan δ at 60 ° C.), rubber hardness at high temperature, elastic modulus, and rubber strength cannot be improved.

  In the present invention, partial hydrogenation of a styrene-diene-styrene copolymer means that 5-60% by weight, more preferably 8-60% by weight, of the polydiene segment is hydrogenated. By hydrogenating the polydiene segment in the above range, the rubber hardness at high temperature while improving wet performance (tan δ at 0 ° C.) and dry performance (tan δ at 60 ° C.) by the vulcanizable segment, Elastic modulus and rubber strength can be improved.

  As the partially hydrogenated elastomer contained in the tire rubber composition of the present invention, a partially hydrogenated elastomer of a styrene-butadiene-styrene copolymer is preferable.

The partially hydrogenated elastomer to be blended in the present invention preferably has a number average molecular weight (hereinafter referred to as “Mn”) of 100,000 to 200,000, more preferably 100,000 to 150,000. By setting the Mn of the partially hydrogenated elastomer to 100,000 or more, the rubber hardness, elastic modulus and rubber strength in a high temperature state can be ensured at a high level. Further, when the Mn of the partially hydrogenated elastomer is 200,000 or less, the processability of the rubber composition can be maintained at a good level. In the present specification, Mn of the partially hydrogenated elastomer is measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

  The partially hydrogenated elastomer blended in the present invention preferably has a styrene content of 40 to 65% by weight, more preferably 45 to 60% by weight. By setting the amount of styrene in the partially hydrogenated elastomer to 40% by weight or more, it is possible to ensure rubber hardness, elastic modulus, and rubber strength at high temperatures. Further, by setting the styrene content of the partially hydrogenated elastomer to 65% by weight or less, the rubber strength can be secured at a high level and the wear resistance can be maintained. The amount of styrene in the partially hydrogenated elastomer is measured by infrared spectroscopic analysis (Hampton method).

  In the present invention, the content of the partially hydrogenated elastomer is 5 to 30% by weight, preferably 7 to 15% by weight, in 100% by weight of the rubber component. By setting the content of the partially hydrogenated elastomer to 5% by weight or more, the wet performance (tan δ at 0 ° C.) and the dry performance (tan δ at 60 ° C.) can be improved. By setting the content of the partially hydrogenated elastomer to 30% by weight or less, rubber hardness, elastic modulus, and rubber strength at a high temperature can be ensured.

  In the rubber composition of the present invention, the rubber component is composed of the partially hydrogenated elastomer and the diene rubber 1 described above. The content of the diene rubber 1 is 95 to 70% by weight, preferably 93 to 85% by weight, in 100% by weight of the rubber component. By setting the content of the diene rubber 1 to 70% by weight or more, rubber hardness, elastic modulus, and rubber strength at a high temperature can be ensured. By setting the content of the diene rubber 1 to 95% by weight or less, wet performance (tan δ at 0 ° C.) and dry performance (tan δ at 60 ° C.) can be improved.

  In the present invention, the diene rubber 1 necessarily contains styrene butadiene rubber SBR1 having a glass transition temperature (hereinafter referred to as “Tg”) of −30 ° C. to −5 ° C. By containing the styrene butadiene rubber SBR1, the balance between the wet performance of the rubber composition (tan δ at 0 ° C.), the rubber hardness, the elastic modulus, and the rubber strength can be further improved.

  The content of the styrene butadiene rubber SBR1 is 95 to 40% by weight, preferably 85 to 55% by weight, in 100% by weight of the rubber component. By setting the content of the styrene butadiene rubber SBR1 to 40% by weight or more, it is possible to secure rubber hardness and rubber strength in a high temperature state, and to improve steering stability and grip performance. Moreover, wet performance (tan delta of 0 degreeC) is securable by making content of specific SBR1 95 weight% or less.

  The Tg of the styrene butadiene rubber SBR1 is −30 ° C. to −5 ° C., preferably −30 ° C. to −15 ° C., more preferably −25 to −10 ° C. Grip performance can be ensured by setting the Tg of SBR1 to -30 ° C or higher. Moreover, wear resistance can be ensured by making Tg of SBR1 into -5 degrees C or less.

  The Mw of SBR1 is preferably 1 million to 1.8 million, more preferably 1.1 million to 1.5 million. By setting Mw of SBR1 to 1 million or more, rubber hardness, elastic modulus, and rubber strength can be secured at a high level. Moreover, the processability of a rubber composition is securable by making Mw of SBR1 into 1.8 million or less.

  In particular, when the rubber composition of the present invention is used as a tire tread for a racing car, the styrene butadiene rubber SBR1 has a glass transition temperature of -30 ° C to -5 ° C and a weight average molecular weight of 1,000,000 to 1,800,000. A certain solution-polymerized styrene butadiene rubber S-SBR is preferable, and the content of the S-SBR may be 95 to 60% by weight in 100% by weight of the rubber component.

  The rubber composition for a tire tread of the present invention can optionally contain, as the diene rubber 1, a diene rubber other than the above-described SBR1. Examples of other diene rubbers include diene rubbers having a Tg lower than −30 ° C., such as styrene butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber having a Tg lower than −30 ° C. The content of the other diene rubber is preferably 55 to 0% by weight, more preferably 38 to 0% by weight in 100% by weight of the rubber component.

In the present invention, as another diene rubber, a diene rubber 2 having a Tg of −50 ° C. or less is preferable. By blending the diene rubber 2 having a Tg of −50 ° C. or less, the viscosity of the rubber composition for a tire tread can be reduced to improve processability, and the rubber hardness at a high temperature can be increased. The Tg of the diene rubber 2 is preferably −50 ° C. or less, more preferably −75 ° C. to −55 ° C.

  Examples of such diene rubber 2 include low Tg styrene butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber. Of these, low Tg styrene butadiene rubber and butadiene rubber are preferable.

  When the diene rubber 2 is blended, it is preferable to further limit the Tg as the SBR1. In particular, the styrene butadiene rubber SBR2 having a glass transition temperature of −30 ° C. to −15 ° C. may be contained in combination with the diene rubber 2, and the SBR2 content is 85 to 40% by weight in 100% by weight of the rubber component. Good. Further, SBR2 may be a terminal-modified styrene butadiene rubber. The functional group that is terminally modified is not particularly limited as long as it is a functional group that is usually applied to a tire rubber composition. Preferred examples of the functional group include a hydroxyl group, a carboxyl group, and an amino group.

  That is, the diene rubber 1 is composed of a styrene butadiene rubber SBR2 having a glass transition temperature of −30 ° C. to −15 ° C. and a diene rubber 2 having a glass transition temperature of −50 ° C. or less, and the content of the styrene butadiene rubber SBR2 Is preferably 85 to 40% by weight in 100% by weight of the rubber component. Thereby, while reducing the viscosity of a rubber composition and making workability favorable, the rubber strength (100 degreeC) in a higher temperature state can be improved.

  The rubber composition for a tire tread of the present invention improves grip performance by blending an aromatic modified terpene resin. The compounding amount of the aromatic modified terpene resin is 2 to 30 parts by weight, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the rubber component. By making the blending amount of the aromatic modified terpene resin 2 parts by weight or more, the steering stability and the wet performance can be improved. By controlling the blending amount of the aromatic-modified terpene resin to 30 parts by weight or less, the increase in the adhesiveness of the rubber composition is suppressed, the adhesion to the molding roll is suppressed, and good molding processability and handleability are maintained. Can do.

  The aromatic modified terpene resin is obtained by polymerizing a terpene and an aromatic compound. Examples of terpenes include α-pinene, β-pinene, dipentene, and limonene. Examples of the aromatic compound include styrene, α-methylstyrene, vinyl toluene, indene and the like. Of these, a styrene-modified terpene resin is preferable as the aromatic-modified terpene resin. Such an aromatic modified terpene resin has good compatibility with the diene rubber, so that the tan δ at 0 ° C. of the rubber composition is increased and the wet grip performance is improved.

  As the aromatic modified terpene resin, one having a softening point of preferably 70 to 160 ° C., more preferably 85 to 150 ° C. may be used. When the softening point of the aromatic modified terpene resin is less than 70 ° C., the effect of improving the grip performance cannot be sufficiently obtained. Moreover, when the softening point of aromatic modified terpene resin exceeds 160 degreeC, there exists a tendency for abrasion resistance to deteriorate. In addition, the softening point of aromatic modified terpene resin shall be measured based on JISK6220-1 (ring ball method).

The rubber composition for a tire tread of the present invention contains 40 to 80 parts by weight of carbon black having a nitrogen adsorption specific surface area of 90 to 200 m ² / g and 40 to 90 parts by weight of silica with respect to 100 parts by weight of the rubber component. The blending amount of the inorganic filler containing carbon black and silica is 80 to 160 parts by weight.

The carbon black used in the rubber composition of the present invention has a nitrogen adsorption specific surface area (N ₂ SA) of 90 to 200 m ² / g, preferably 95 to 180 m ² / g. By making N ₂ SA of carbon black 90 m ² / g or more, grip performance can be ensured. Further, by the N ₂ SA of the carbon black below 200m ² / g, it is possible to ensure the wear resistance. The N ₂ SA of carbon black is determined according to JIS K6217-2.

  The compounding quantity of carbon black is 40-80 weight part with respect to 100 weight part of rubber components, Preferably it is 40-70 weight part. When the blending amount of carbon black is less than 40 parts by weight, rubber strength and heat build-up are deteriorated. Moreover, the abrasion resistance in which the compounding amount of carbon black exceeds 80 parts by weight is deteriorated, and the wet performance is also deteriorated.

  The rubber composition for a tire tread of the present invention contains 40 to 90 parts by weight, preferably 50 to 85 parts by weight of silica with respect to 100 parts by weight of the rubber component. By setting the amount of silica to 40 parts by weight or more, tan δ (0 ° C.) can be increased and wet grip performance can be improved. Further, by setting the blending amount of silica to 90 parts by weight or less, the rubber strength and rigidity of the rubber composition can be secured, and the steering stability and the wear resistance can be improved. As the silica, silica usually used in a rubber composition for a tire tread, for example, wet method silica, dry method silica, or surface-treated silica can be used.

  The total amount of the inorganic filler containing carbon black and silica is 80 to 160 parts by weight, preferably 85 to 130 parts by weight, per 100 parts by weight of the rubber component. By making the total of inorganic fillers including carbon black and silica 80 parts by weight or more, wet grip performance can be ensured. Moreover, wear resistance and workability are securable by making the sum total of an inorganic filler into 160 weight part or less. As inorganic fillers other than carbon black and silica, for example, clay, mica, talc, calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide and the like can be blended.

  In the rubber composition of the present invention, by adding a silane coupling agent together with silica, the dispersibility of silica is improved and the reinforcement with the diene rubber is further increased. The silane coupling agent is preferably added in an amount of 2 to 20% by weight, more preferably 5 to 15% by weight, based on the amount of silica. When the compounding amount of the silane coupling agent is less than 2% by weight of the silica weight, the effect of improving the dispersibility of silica cannot be obtained sufficiently. On the other hand, when the silane coupling agent exceeds 20% by weight, the silane coupling agents are polymerized with each other, and a desired effect cannot be obtained.

  The silane coupling agent is not particularly limited, but is preferably a sulfur-containing silane coupling agent, such as bis- (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, Examples thereof include 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, and 3-octanoylthiopropyltriethoxysilane. Of these, bis- (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide are preferable.

  The tire tread rubber composition generally includes a vulcanization or crosslinking agent, a vulcanization accelerator, an anti-aging agent, a plasticizer, a processing aid, a liquid polymer, a thermosetting resin, and the like. Various compounding agents used can be blended. Such a compounding agent can be kneaded by a general method to form a rubber composition, which can be used for vulcanization or crosslinking. The compounding amounts of these compounding agents can be the conventional general compounding amounts as long as they do not contradict the purpose of the present invention. The rubber composition for a tire tread can be produced by mixing each of the above components using a known rubber kneading machine such as a Banbury mixer, a kneader, or a roll.

  The rubber composition for a tire tread of the present invention can improve steering stability, dry performance, and wet performance to a level higher than the conventional level. This rubber composition can be suitably used for wet-dry combined grooved tires for racing cars and pneumatic tires for high-performance passenger cars traveling on public roads.

In particular, when used in a tread of a wet-dry combined grooved tire for a racing car, 5-30% by weight of an elastomer partially hydrogenated with a styrene-diene-styrene copolymer and 95 of a diene rubber 1 are used. It is a rubber composition in which 80 to 160 parts by weight of an inorganic filler and 2 to 10 parts by weight of an aromatic modified terpene resin are blended with 100 parts by weight of a rubber component that is 100% by weight in total with 70% by weight, 95-60% by weight of the diene rubber 1 is a solution-polymerized styrene butadiene rubber S-SBR having a glass transition temperature of −30 ° C. to −5 ° C. and a weight average molecular weight of 1,000,000 to 1,800,000, and the inorganic filler, silica tire tread rubber composition comprising 40 to 90 parts by weight and the nitrogen adsorption specific surface area from 40 to 80 parts by weight of carbon black 130~200m ² / g Preferred. Wet and dry grooved tires for racing cars using this rubber composition have excellent handling stability, dry grip performance and wet grip performance at high speeds, and improved wear resistance. Can do.

When used in a tread for a pneumatic tire for a high-performance passenger car, 5-30% by weight of an elastomer partially hydrogenated with a styrene-diene-styrene copolymer and 95-70% by weight of a diene rubber 1 are used. A rubber composition in which 80 to 160 parts by weight of an inorganic filler and 2 to 30 parts by weight of an aromatic modified terpene resin are blended with 100 parts by weight of a rubber component that is 100% by weight in total, the diene rubber 1 comprises a styrene butadiene rubber SBR2 having a glass transition temperature of −30 ° C. to −15 ° C. and a diene rubber 2 having a glass transition temperature of −50 ° C. or less, and the content of the styrene butadiene rubber SBR2 is the rubber component as well as a 85 to 40 wt% in 100 wt%, nitrogen adsorption specific surface area of the carbon black rubber for tire tread is 90~130m ² / g Composition. A pneumatic tire for a high-performance passenger car using this rubber composition can be excellent in handling stability in a high-speed range, and grip force on a dry road surface and a wet road surface. Moreover, since the rubber composition has a low viscosity and excellent processability, a high-quality passenger car tire can be stably produced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  22 kinds of rubber compositions for tire treads (Examples 1 to 8, Comparative Examples 1 to 16) having the compounding ingredients shown in Table 5 as common ingredients and the compositions shown in Tables 1 to 4, sulfur and vulcanization accelerators The components except for were prepared by adding sulfur and a vulcanization accelerator to an open roll and kneading the master batch which was kneaded for 5 minutes at 160 ° C. with a 1.8 L closed mixer. In Tables 1 to 4, the net compounding amount of each rubber component is described in parentheses for SBR containing oil-extended oil. Moreover, the addition amount of the common compounding agent described in Table 5 was expressed in parts by weight with respect to 100 parts by weight of the rubber component described in Tables 1 to 4 (net amount of rubber 100 parts by weight).

  In addition, four types of rubber compositions for tire treads described in Tables 1 and 2 (Examples 1 to 4 are rubber compositions suitable for treads of wet-dry combined grooved tires for automobiles for competition use. The four types of rubber compositions for tire treads described in 3 and 4 (Examples 5 to 8) are rubber compositions suitable for treads of pneumatic tires for high-performance passenger cars.

Processability Among the obtained rubber compositions, the viscosity of 13 types of rubber compositions for tire treads (Examples 5 to 8 and Comparative Examples 8 to 16) was measured with a Mooney viscometer according to JIS K6300. Using a type rotor (38.1 mm diameter, 5.5 mm thickness), measurement was performed under the conditions of a preheating time of 1 minute, a rotor rotation time of 4 minutes, 100 ° C., and 2 rpm. The obtained results are shown in the column of “workability” in Tables 3 and 4, with the value of Comparative Example 8 being 100. The smaller the index is, the lower the rubber viscosity is, and the better the processability is.

  The obtained 24 types of rubber compositions for tire treads were press vulcanized at 160 ° C. for 20 minutes in a mold having a predetermined shape to prepare test pieces, and rubber hardness (60 ° C) and tensile strength at break (60 ° C or 100 ° C), and tan δ (0 ° C and 60 ° C).

Rubber hardness (60 ℃)
The rubber hardness of the obtained test piece was measured at a temperature of 60 ° C. with a durometer type A according to JIS K6253. The obtained results are shown in Tables 1 and 2, with the value of Comparative Example 1 being 100, and in Tables 3 and 4, with the value of Comparative Example 8 being 100, the “rubber hardness (60 ° C.)” in Tables 1 to 4 Shown in the column. As this index is 97 or higher, the higher the value, the higher the rubber hardness and the better the mechanical properties, and the better the steering stability and grip performance when using a pneumatic tire.

Tensile strength at break (60 ° C, 100 ° C)
From the obtained test piece, a JIS No. 3 dumbbell-type test piece (thickness 2 mm) is punched out in accordance with JIS K6251 and tested at a temperature of 60 ° C. or 100 ° C. at a pulling rate of 500 mm / min to measure the tensile breaking strength. did. Test pieces of 11 types of rubber compositions for tire treads described in Tables 1 and 2 (Examples 1 to 4 and Comparative Examples 1 to 7) were measured for tensile strength at 60 ° C. The results are shown in the column of “Break Strength (60 ° C.)” in Tables 1 and 2 as indices with the value of Comparative Example 1 as 100. Test pieces of 18 kinds of rubber compositions for tire treads described in Tables 3 and 4 (Examples 5 to 8 and Comparative Examples 8 to 16) were measured for tensile strength at 100 ° C., and the obtained results were as follows. The results are shown in the column of “Breaking Strength (100 ° C.)” in Tables 3 and 4 as indices with the value of Comparative Example 8 as 100. The larger these indices, the greater the tensile strength at high temperatures and the better the mechanical properties, and the better the steering stability, grip performance and wear resistance when made into a pneumatic tire.

Wet performance (tan δ at 0 ° C), dry performance (tan δ at 60 ° C)
Using the obtained test piece, loss tangent tan δ (0 ° C. and 60 ° C.) was evaluated as an index of wet performance and dry performance. Tanδ was measured using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho under the conditions of initial strain 10%, amplitude ± 2%, frequency 20 Hz, temperature 0 ° C. and 60 ° C. The obtained results are shown as “tan δ (0 ° C.)” and “tan δ” in Tables 1 to 4 as indexes with the value of Comparative Example 1 being 100 in Tables 1 and 2, and the value of Comparative Example 8 being 100 in Tables 3 and 4. (60 ° C.) ”. The larger the index of tan δ (0 ° C.), the better the wet performance. Also, the larger the index of tan δ (60 ° C.), the better the dry performance.

In addition, the kind of raw material used in Tables 1-4 is shown below.
S-SBR1: solution-polymerized styrene butadiene rubber end-modified with hydroxyl groups, styrene content 36% by weight, vinyl content 64% by weight, Mw 1,470,000, Tg -13 ° C., 100 parts by weight of rubber component An oil exhibition containing 37.5 parts by weight of oil, Toughden E680 manufactured by Asahi Kasei Chemicals
S-SBR2: solution-polymerized styrene butadiene rubber end-modified with a hydroxyl group, styrene content is 37% by weight, vinyl content is 42% by weight, Mw is 1.26 million, Tg is −27 ° C., 100 parts by weight of rubber component Oil exhibition containing 37.5 parts by weight of oil, Toughden E581 manufactured by Asahi Kasei Chemicals
E-SBR: Unmodified emulsion-polymerized styrene butadiene rubber, styrene content 40% by weight, vinyl content 14% by weight, Mw 750,000, Tg −23 ° C., oil content 37 parts by weight with respect to 100 parts by weight of rubber component. Oil exhibition including 5 parts by weight, Nipol 1739 manufactured by Nippon Zeon
S-SBR3: solution polymerized styrene butadiene rubber, Tg of −71 ° C., oil exhibition product containing 37.5 parts by weight of oil with respect to 100 parts by weight of rubber component, Nipol 1834 manufactured by Zeon Corporation
BR: butadiene rubber, Tg of −106 ° C., Nipol BR1220 manufactured by Nippon Zeon
Elastomer 1: Styrene-butadiene-styrene copolymer, 48% by weight of styrene, 65800 Mn, Tufprene 126S manufactured by Asahi Kasei Chemicals
Elastomer 2: Elastomer partially hydrogenated styrene-butadiene-styrene copolymer, 57% by weight of styrene, 103,000 Mn, manufactured by Asahi Kasei Chemicals O. E. S1611
Elastomer 3: Elastomer completely hydrogenated with styrene-butadiene-styrene copolymer, styrene content 61% by weight, Mn 96700, manufactured by Asahi Kasei Chemicals O. E. L605
Silica: Rhodia Zeosil 1165MP, CTAB specific surface area of 1592 m ² / g
-Coupling agent: Silane coupling agent, Si69 manufactured by Evonik Degussa
Carbon black 1: carbon black, Toast carbon company's seast 9, N ₂ SA = 142 m ² / g
Carbon black 2: Carbon black, Toast carbon company's seast 7HM, N ₂ SA = 123 m ² / g
Carbon black 3: Carbon black, Toast Carbon Co., Ltd. seast KHA, N ₂ SA = 77 m ² / g
Terpene resin: Aromatic modified terpene resin having a softening point of 125 ° C., YS resin TO-125 manufactured by Yashara Chemical Co., Ltd.
・ Oil: Showa Shell Sekiyu Extract 4 S

The types of raw materials used in Table 5 are shown below.
-Zinc flower: Zinc oxide 3 types manufactured by Shodo Chemical Industry Co., Ltd.-Stearic acid: Bead Stearic Acid YR manufactured by NOF Corporation
・ Sulfur: Fine powder sulfur with Jinhua seal oil manufactured by Tsurumi Chemical Co., Ltd. ・ Vulcanization accelerator: CBS accelerator, Nouchira CZ-G manufactured by Ouchi Shinsei Chemical Co., Ltd.

  As is clear from Tables 1 and 2, the rubber compositions for tire treads of Examples 1 to 8 have rubber hardness (60 ° C.), tensile breaking strength (60 ° C. or 100 ° C.), wet performance tan δ (0 ° C.) and dryness. It was confirmed that the performance tan δ (60 ° C.) was high, and it was confirmed that the steering stability, the dry performance and the wet performance were excellent.

  Since the rubber composition of Comparative Example 1 was blended with a styrene-butadiene-styrene copolymer (non-hydrogenated elastomer 1) without blending the partially hydrogenated elastomer 2, the tensile breaking strength (60 ° C.), As in Example 2, it is impossible to improve the wet performance tan δ (0 ° C.) and the dry performance tan δ (60 ° C.).

  Since the rubber composition of Comparative Example 2 was blended with the elastomer 3 in which the styrene-butadiene-styrene copolymer was completely hydrogenated without blending the partially hydrogenated elastomer 2, the tensile breaking strength (60 ° C.) and the dry performance tan δ (60 ° C.) deteriorates.

  Since the rubber composition of Comparative Example 3 does not contain the partially hydrogenated elastomer 2, the wet performance tan δ (0 ° C.) and the dry performance tan δ (60 ° C.) are deteriorated.

  In the rubber composition of Comparative Example 4, since the blending amount of the partially hydrogenated elastomer 2 exceeded 30 weight, the rubber hardness (60 ° C.) and the tensile strength at break (60 ° C.) deteriorate.

  Since the rubber composition of Comparative Example 5 does not contain an aromatic modified terpene resin, wet performance tan δ (0 ° C.) and dry performance tan δ (60 ° C.) are deteriorated.

  In the rubber composition of Comparative Example 6, since the blending amount of carbon black is less than 40 parts by weight, the dry performance tan δ (60 ° C.) is deteriorated.

  In the rubber composition of Comparative Example 7, since the compounding amount of silica is less than 40 parts by weight and the compounding amount of carbon black is more than 80 parts by weight, the wet performance tan δ (0 ° C.) is deteriorated.

  As is clear from Table 3, the rubber composition of Comparative Example 8 was blended with a styrene-butadiene-styrene copolymer (non-hydrogenated elastomer 1) without blending the partially hydrogenated elastomer 2. As in Example 5, it is impossible to improve the tensile strength at break (100 ° C.), the wet performance tan δ (0 ° C.), and the dry performance tan δ (60 ° C.).

  Since the rubber composition of Comparative Example 9 was blended with the elastomer 3 in which the styrene-butadiene-styrene copolymer was completely hydrogenated without blending the partially hydrogenated elastomer 2, the tensile breaking strength (100 ° C.) was deteriorated. .

  Since the rubber composition of Comparative Example 10 does not contain the partially hydrogenated elastomer 2, processability, wet performance tan δ (0 ° C.), and dry performance tan δ (60 ° C.) deteriorate.

  In the rubber composition of Comparative Example 11, since the blended amount of the partially hydrogenated elastomer 2 exceeded 30 weight, the rubber hardness (60 ° C.) and the tensile strength at break (100 ° C.) deteriorate.

  In the rubber composition of Comparative Example 12, the compounding amount of silica exceeds 90 parts by weight and the total amount of inorganic fillers exceeds 160 parts by weight.

  In the rubber composition of Comparative Example 13, since the compounding amount of silica is less than 40 parts by weight and the total amount of inorganic fillers is less than 80 parts by weight, rubber hardness (60 ° C.), wet performance tan δ (0 ° C.) and dry Performance tan δ (60 ° C.) deteriorates.

  Since the rubber composition of Comparative Example 14 does not contain an aromatic modified terpene resin, the wet performance tan δ (0 ° C.) deteriorates.

  In the rubber composition of Comparative Example 15, since the blending amount of the aromatic modified terpene resin exceeds 30 parts by weight, the tensile strength at break (100 ° C.) is deteriorated.

In the rubber composition of Comparative Example 16, since N ₂ SA of carbon black 3 is less than 90 m ² / g, rubber hardness (60 ° C.), tensile strength at break (100 ° C.), wet performance tan δ (0 ° C.) and dry Performance tan δ (60 ° C.) deteriorates.

Claims (7)

100 parts by weight of a rubber component which is 100% by weight in total of 5 to 30% by weight of an elastomer partially hydrogenated with a styrene-diene-styrene copolymer and 95 to 70% by weight of a diene rubber 1 A rubber composition containing 80 to 160 parts by weight of a filler and 2 to 30 parts by weight of an aromatic modified terpene resin, wherein the glass transition temperature of the diene rubber 1 is -30 ° C to -5 ° C. The styrene-butadiene rubber SBR1 is 95 to 40% by weight, and the inorganic filler is composed of 40 to 90 parts by weight of silica and 40 to 80 parts by weight of carbon black having a nitrogen adsorption specific surface area of 90 to 200 m ² / g. A rubber composition for a tire tread characterized by the above.   The rubber composition for a tire tread according to claim 1, wherein the elastomer is an elastomer obtained by partially hydrogenating a styrene-butadiene-styrene copolymer. The styrene butadiene rubber SBR1 is a solution-polymerized styrene butadiene rubber S-SBR having a glass transition temperature of −30 ° C. to −5 ° C. and a weight average molecular weight of 1,000,000 to 1,800,000, and the content of the S-SBR is It is 95 to 60% by weight in 100% by weight of the rubber component, the nitrogen adsorption specific surface area of the carbon black is 130 to 200 m ² / g, and the blending amount of the aromatic modified terpene resin is 10 parts by weight or less. The rubber composition for a tire tread according to claim 1 or 2. The diene rubber 1 comprises a styrene butadiene rubber SBR2 having a glass transition temperature of −30 ° C. to −15 ° C. and a diene rubber 2 having a glass transition temperature of −50 ° C. or less, and the content of the styrene butadiene rubber SBR2 3. The tire tread according to claim 1, wherein the carbon black is 85 to 40% by weight in 100% by weight of the rubber component, and the nitrogen adsorption specific surface area of the carbon black is 90 to 130 m ² / g. Rubber composition.   The rubber composition for a tire tread according to claim 4, wherein the diene rubber 2 is a styrene butadiene rubber or a butadiene rubber having a glass transition temperature of -50 ° C or lower.   6. The tire tread rubber composition according to claim 4, wherein the styrene butadiene rubber SBR2 is a terminal-modified styrene butadiene rubber.   The pneumatic tire which uses the rubber composition for tire treads in any one of Claims 1-6.