JP2015110704A - Tread rubber composition for high performance tire and high performance tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tread rubber composition for a high performance tire capable of improving initial grip performance and grip performance on a wet road surface and grip performance and anti-wear performance on a dry-up road surface in good balance, and to provide a high performance tire having a tread prepared by using the rubber composition.SOLUTION: There is provided a tread rubber composition for a high performance tire which comprises a styrene butadiene rubber and a hydrogenated styrene-based thermoplastic elastomer and has a content of the styrene butadiene rubber of 60 to 97 mass% and a content of the hydrogenated styrene-based thermoplastic of 3 to 40 mass% in 100 mass% of a rubber component.

Description

The present invention relates to a tread rubber composition for a high-performance wet tire and a high-performance wet tire having a tread produced using the rubber composition.

The high-performance wet tire tread rubber composition has strong initial grip performance, grip performance on wet road surfaces, grip performance on dry-up road surfaces (road surfaces dried from wet conditions), and wear resistance. In order to ensure these performances, various ideas have been conventionally made.

For example, Patent Document 1 discloses a technique of blending an inorganic compound powder such as aluminum hydroxide as a technique for improving grip performance on a wet road surface. However, when aluminum hydroxide is blended, there is room for improvement in that the fracture strength decreases and the wear resistance performance deteriorates.

Further, as a technique for improving the initial grip performance, a technique for lowering the glass transition point (Tg) of the rubber composition is known. However, when the Tg of the rubber composition is lowered, tan δ in the high temperature region is lowered, There is room for improvement in terms of poor grip performance on dry-up surfaces.

Further, as a technique for increasing the grip performance on the dry-up road surface, a technique for increasing the Tg of the rubber composition is known. However, if the Tg of the rubber composition is decreased, the rubber composition becomes too hard in the normal temperature region. There is room for improvement in that the initial grip performance on wet road surfaces deteriorates and the wear resistance performance on dry-up road surfaces deteriorates.

Thus, it is difficult to achieve both the initial grip performance and grip performance on wet road surfaces, and the grip performance and wear resistance performance on dry-up road surfaces, and a method for improving these performances in a well-balanced manner is required. Yes.

JP 2002-338750 A

The present invention provides a tread rubber composition for a high-performance wet tire that solves the above-mentioned problems and can improve the initial grip performance and grip performance on a wet road surface, and the grip performance and wear resistance performance on a dry-up road surface in a balanced manner, and An object of the present invention is to provide a high-performance wet tire having a tread produced using the rubber composition.

The present invention contains a styrene-butadiene rubber and a hydrogenated styrene-based thermoplastic elastomer, wherein the content of the styrene-butadiene rubber is 60 to 97% by mass in 100% by mass of the rubber component, and the content of the hydrogenated styrene-based thermoplastic elastomer The present invention relates to a tread rubber composition for a high-performance wet tire having an amount of 3 to 40% by mass.

The hydrogenated styrene thermoplastic elastomer preferably has a hydrogenation rate of 20 to 100 mol%.

The hydrogenated styrene-based thermoplastic elastomer has a block having a styrene block at both ends and a block containing at least one conjugated diene selected from the group consisting of butadiene, butylene, and ethylene, and styrene in the main chain. A hydrogenated product of the copolymer is preferable.

The hydrogenated styrene thermoplastic elastomer preferably has a weight average molecular weight of 50,000 to 500,000.

It contains carbon black, silica, and an inorganic reinforcing agent represented by the following formula. The amount of the carbon black is 10 to 50 parts by mass, and the content of the silica is 100 parts by mass of the rubber component. It is preferable that 30-100 mass parts and content of the said inorganic reinforcing agent are 5-30 mass parts.
kM ₁ · xSiO _y · zH ₂ O
(Wherein M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 0) 10 is an integer, y is an integer of 2 to 5, and z is an integer of 0 to 10.)

The inorganic reinforcing agent is preferably aluminum hydroxide.

The present invention also relates to a high-performance wet tire having a tread produced using the rubber composition.

According to the present invention, since it is a tread rubber composition for high-performance wet tires each containing a predetermined amount of styrene-butadiene rubber and hydrogenated styrene-based thermoplastic elastomer, initial grip performance and grip performance on a wet road surface, and dry up It is possible to provide a high-performance wet tire in which the grip performance and wear resistance performance on the road surface are improved in a well-balanced manner.

The rubber composition of the present invention can ensure good rubber elasticity in a wide temperature range by containing a predetermined amount of styrene-butadiene rubber and hydrogenated styrene-based thermoplastic elastomer, respectively. While maintaining the wear performance, the initial grip performance on the wet road surface, the grip performance on the wet road surface (wet grip performance), and the grip performance on the dry-up road surface (dry grip performance) can be improved. Thereby, it is possible to secure these performances that are difficult to achieve in the past in a high-order and well-balanced manner.

The rubber composition of the present invention contains a hydrogenated styrene thermoplastic elastomer as a rubber component. The hydrogenated styrene thermoplastic elastomer is obtained by hydrogenating a block copolymer of a styrene monomer and a conjugated diene monomer.

Examples of the styrene monomer include styrene and alkyl-substituted styrene such as α-methylstyrene, and styrene is preferably used. Examples of the conjugated diene monomer include butadiene, isoprene, butylene, ethylene, 1,3-pentadiene, and butadiene, butylene, and ethylene are preferable, and butadiene is more preferable.

The hydrogenated styrenic thermoplastic elastomer is a block copolymer having a styrene block at both ends and a block containing at least one conjugated diene selected from the group consisting of butadiene, butylene and ethylene, and a block containing styrene in the main chain. It is preferably a hydrogenated product of a polymer, more preferably a hydrogenated product of a block copolymer having a styrene block at both ends and a block of a random copolymer of styrene and butadiene in the main chain. . When there is no styrene block at both ends, there is a possibility that sufficient wet grip performance and dry grip performance cannot be obtained. Moreover, when the main chain is only a styrene block, the hardness of the rubber increases in the normal temperature region, and the initial grip performance and wear resistance performance may be deteriorated.

Examples of commercially available hydrogenated styrene-based thermoplastic elastomers include S.A. manufactured by Asahi Kasei Corporation. O. E. Series.

The hydrogenation rate of the hydrogenated styrene thermoplastic elastomer is preferably 20 to 100 mol%, more preferably 30 to 100 mol%. If it is less than 20 mol%, sufficient wet grip performance and dry grip performance may not be obtained.
In this specification, the hydrogenation rate of the hydrogenated styrene-based thermoplastic elastomer is the ratio of the double bond of the conjugated diene block to which hydrogen has been added, and a JNM-ECA series device manufactured by JEOL Ltd. is used. , H ¹ -NMR calculated from the amount of decrease in the spectrum of the unsaturated bond.

The weight average molecular weight (Mw) of the hydrogenated styrene thermoplastic elastomer is preferably 50,000 or more, more preferably 60,000 or more, still more preferably 70,000 or more, particularly preferably 100,000 or more, and most preferably. 130,000 or more. The Mw is preferably 500,000 or less, more preferably 450,000 or less, and still more preferably 400,000 or less. If it is less than 50,000, sufficient fracture characteristics cannot be secured and the wear resistance may be deteriorated. If it exceeds 500,000, the hardness of the rubber in the normal temperature region increases and the initial grip performance deteriorates. There is a risk.
In this specification, Mw is the value measured in standard polystyrene conversion based on the measured value by a gel permeation chromatograph (GPC).

The Tg of the hydrogenated styrenic thermoplastic elastomer is preferably −20 ° C. or higher, more preferably 0 ° C. or higher. The Tg is preferably 40 ° C. or lower, more preferably 30 ° C. or lower. If it is lower than −20 ° C., the wet grip performance, the dry grip performance and the wear resistance may be deteriorated, and if it exceeds 40 ° C., the initial grip performance may be deteriorated.
In this specification, Tg is heated at a rate of temperature increase of 10 ° C./min using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Co., Ltd. according to JIS K7121. The measured value (midpoint glass transition temperature).

The styrene content of the hydrogenated styrene thermoplastic elastomer is preferably 20% by mass or more, more preferably 25% by mass or more. Moreover, this styrene content becomes like this. Preferably it is 70 mass% or less, More preferably, it is 65 mass% or less. If it is less than 20% by mass, the wet grip performance may not be sufficiently exhibited, and if it exceeds 70% by mass, the wear resistance may be deteriorated.
In the present specification, the styrene content is a value calculated by H ¹ -NMR measurement.

The content of the hydrogenated styrene thermoplastic elastomer is 3% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, in 100% by mass of the rubber component. Moreover, this content is 40 mass% or less, Preferably it is 30 mass% or less, More preferably, it is 20 mass% or less. If it is less than 3% by mass, sufficient wet grip performance and dry grip performance cannot be exhibited. If it exceeds 40% by mass, the hardness of the rubber in the normal temperature region is increased, and the initial grip performance and wear resistance are deteriorated. .

The rubber composition of the present invention contains styrene butadiene rubber (SBR) as a rubber component. The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), and the like can be used.

The vinyl content of SBR is preferably 20% by mass or more, more preferably 30% by mass or more. Moreover, this vinyl content becomes like this. Preferably it is 80 mass% or less, More preferably, it is 70 mass% or less. If it is less than 20% by mass, sufficient wet grip performance and dry grip performance may not be obtained, and if it exceeds 80% by mass, the wear resistance tends to deteriorate.
In addition, the vinyl content of SBR is a value measured by an infrared absorption spectrum analysis method.

The styrene content of SBR is preferably 20% by mass, more preferably 25% by mass or more. Moreover, this styrene content becomes like this. Preferably it is 60 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 45 mass% or less. If it is less than 20% by mass, sufficient wet grip performance and dry grip performance tend not to be obtained. If it exceeds 60% by mass, not only the wear resistance is deteriorated, but also temperature dependency increases, There is a tendency for performance changes to increase.

The glass transition point (Tg) of SBR is preferably −50 ° C. or higher, more preferably −40 ° C. or higher. The Tg is preferably 0 ° C. or lower, more preferably −10 ° C. or lower. If it is less than −50 ° C., the wet grip performance and the dry grip performance may be deteriorated, and if it exceeds 0 ° C., the initial grip performance and the wear resistance performance may be deteriorated.

Content of SBR is 60 mass% or more in 100 mass% of rubber components, Preferably it is 70 mass% or more. Moreover, this content is 97 mass% or less, Preferably it is 95 mass% or less. If it is less than 60% by mass, sufficient heat resistance and wear resistance performance cannot be obtained. If it exceeds 97% by mass, the content of the hydrogenated styrene-based thermoplastic elastomer is reduced, and sufficient wet grip performance and dry grip are achieved. Performance may not be obtained.

The rubber composition of the present invention may contain other rubber components in addition to the hydrogenated styrene thermoplastic elastomer and SBR. Other rubber components include natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber. (NBR), butyl rubber (IIR), halogenated butyl rubber (X-IIR) and the like.

The rubber composition of the present invention preferably contains silica from the viewpoint of wet grip performance. Examples of the silica include dry method silica (anhydrous silica), wet method silica (hydrous silica), and the like. Of these, wet-process silica is preferred because it has many silanol groups.

The cetyltrimethylammonium bromide adsorption specific surface area (CTAB) of silica is preferably 100 to 300 m ² / g because good wet grip performance, dry grip performance and wear resistance performance can be obtained. Moreover, it is preferable that the dibutyl phthalate oil absorption (DBP) of a silica is 150-300 mL / 100g for the same reason.
The CTAB for silica is a value measured according to the method described in ASTM D3765-80, and the DBP is according to the method described in JIS K 6221 6.1.2, Method A.

The content of silica is preferably 30 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 30 parts by mass, there is a tendency that sufficient wet grip performance improvement effect cannot be obtained. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less. When the amount exceeds 100 parts by mass, silica is difficult to disperse and wear resistance may be deteriorated.

The rubber composition of the present invention preferably contains carbon black from the viewpoint of wear resistance. Examples of carbon black include carbon black produced by an oil furnace method, and two or more types having different colloidal characteristics may be used in combination. Specific examples include GPF, HAF, ISAF, and SAF. Among these, SAF is preferable.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 70 to 250 m ² / g, because it can provide good wet grip performance, dry grip performance and wear resistance, and 110 to 200 m ² / g. Is more preferable. Moreover, the dibutyl phthalate oil absorption (DBP) of carbon black is preferably 50 to 250 ml / 100 g for the same reason.
In addition, N ₂ SA of carbon black is a value measured according to JIS K 6217-2: 2001, and DBP is a value measured according to JIS K6217-4: 2001.

The content of carbon black is preferably 10 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 10 parts by mass, sufficient wet grip performance, dry grip performance and wear resistance performance may not be obtained. The content is preferably 50 parts by mass or less, more preferably 35 parts by mass or less. If it exceeds 50 parts by mass, the contribution to wet grip performance tends to be small.

The rubber composition of the present invention preferably contains an inorganic reinforcing agent represented by the following formula from the viewpoint that wet grip performance is further improved and the effects of the present invention can be obtained satisfactorily.
kM ₁ · xSiO _y · zH ₂ O
(Wherein M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 0) 10 is an integer, y is an integer of 2 to 5, and z is an integer of 0 to 10.)

As the inorganic reinforcing agent represented by the above formula, alumina, alumina hydrate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, talc, titanium white, titanium black, calcium oxide, calcium hydroxide, aluminum magnesium oxide, clay Pyrophyllite, bentonite, aluminum silicate, magnesium silicate, calcium silicate, aluminum calcium silicate, magnesium silicate and the like. These inorganic compounds may be used alone or in combination of two or more. Among these, because the effect of the present invention can be obtained more suitably, in the formula, M ₁ is a hydroxide of at least one metal selected from the group consisting of Al, Mg, Ti and Ca. Preferably, M ₁ is more preferably an Al hydroxide (aluminum hydroxide).

The average primary particle diameter of the inorganic reinforcing agent is preferably 0.5 μm or more, more preferably 0.8 μm or more. When the thickness is less than 0.5 μm, it is difficult to disperse the inorganic reinforcing agent, and the wear resistance tends to deteriorate. The average primary particle size is preferably 10 μm or less, more preferably 5 μm or less. When it exceeds 10 μm, the inorganic reinforcing agent serves as a fracture nucleus and wear resistance tends to deteriorate.
In addition, in this invention, the average primary particle diameter of the said inorganic compound is a number average particle diameter, and is measured with a transmission electron microscope.

The content of the inorganic reinforcing agent is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 mass parts, there exists a possibility that the improvement effect of wet grip performance may be small. The total content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less. If it exceeds 30 parts by mass, poor dispersion may occur, and the wear resistance performance may deteriorate.

The total content of carbon black, silica and the above inorganic compound is preferably 60 parts by mass or more, more preferably 90 parts by mass or more with respect to 100 parts by mass of the rubber component. The total content is preferably 170 parts by mass or less, more preferably 140 parts by mass or less. When the total content is within the above range, the effects of the present invention can be more suitably obtained.

In addition, when mix | blending a silica with the rubber composition of this invention, it is preferable to use a silane coupling agent together with a silica. The silane coupling agent is not particularly limited. For example, bis (3-triethoxysilylpropyl) polysulfide, bis (2-triethoxysilylethyl) polysulfide, bis (3-trimethoxysilylpropyl) polysulfide, bis (2- Trimethoxysilylethyl) polysulfide, bis (4-triethoxysilylbutyl) polysulfide, bis (4-trimethoxysilylbutyl) polysulfide and the like. Of these, bis (3-triethoxysilylpropyl) polysulfide and bis (2-triethoxysilylethyl) polysulfide are preferable, and bis (3-triethoxysilylpropyl) tetrasulfide and bis (2-triethoxysilylethyl) tetrasulfide are preferable. Is more preferable.

When mix | blending a silane coupling agent, content of a silane coupling agent becomes like this. Preferably it is 5 mass parts or more with respect to 100 mass parts of silica, More preferably, it is 7 mass parts or more. If it is less than 5 parts by mass, the wear resistance performance tends to decrease. The content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. If it exceeds 20 parts by mass, there is a tendency that an improvement effect commensurate with the increase in cost cannot be obtained.

The rubber composition of the present invention preferably contains a softener from the viewpoints of wet grip performance, dry grip performance, initial grip performance, and the like. Although it does not specifically limit as a softening agent, Oil, a liquid diene polymer, etc. are mentioned.

Examples of the oil include process oils such as paraffinic, aroma-based and naphthenic process oils.

The oil content is preferably 20 parts by mass or more, and more preferably 35 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 70 mass parts or less, More preferably, it is 60 mass parts or less. If it is less than 20 parts by mass, the effect of addition may not be sufficiently obtained. When it exceeds 70 mass parts, there exists a tendency for abrasion resistance performance to deteriorate.
In the present specification, the oil content includes the amount of oil contained in the oil-extended rubber.

The liquid diene polymer is a diene polymer in a liquid state at normal temperature (25 ° C.).
The weight average molecular weight (Mw) of the liquid diene polymer is preferably 3.0 × 10 ^{3 to} 1.0 × 10 ⁵ , and preferably 4.0 × 10 ^{3 to} 1.5 × 10 ^4. More preferred. If it is less than 3.0 × 10 ³ , the fracture characteristics are deteriorated, and there is a possibility that sufficient wear resistance cannot be ensured. On the other hand, if it exceeds 1.0 × 10 ⁵ , the viscosity of the polymerization solution becomes too high, and the productivity may be deteriorated.

Examples of the liquid diene polymer include a liquid styrene butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), a liquid styrene isoprene copolymer (liquid SIR), and the like. It is done. Among these, liquid SBR is preferable because it provides a good balance between wear resistance, stable wet grip performance during running, and dry grip performance.

The styrene content of the liquid SBR is preferably 10 to 45% by mass, more preferably 15 to 40% by mass, from the viewpoint of wet grip performance and dry grip performance.

The content of the liquid diene polymer is preferably 30 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 120 mass parts or less, More preferably, it is 100 mass parts or less. If it is less than 30 parts by mass, sufficient wet grip performance and dry grip performance tend not to be obtained, and if it exceeds 120 parts by mass, wear resistance tends to deteriorate.

In addition to the above components, the rubber composition of the present invention includes compounding agents generally used in the tire industry, for example, vulcanizing agents such as resins, zinc oxide, stearic acid, anti-aging agents, waxes and sulfur. A material such as a vulcanization accelerator may be appropriately blended.

The resin is not particularly limited, and examples thereof include phenol resins, coumarone indene resins, styrene resins, rosin resins, and DCPD resins. Among these, a coumarone indene resin is preferable because the effects of the present invention can be more suitably obtained. The content of the resin is preferably 1 to 30 parts by mass, more preferably 3 to 15 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, and guanidine vulcanization accelerators. Among them, thiazole and thiuram vulcanization accelerators can be preferably used.

Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Among them, di-2-benzothia Zolyl disulfide is preferred. Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N), etc. preferable.

The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, this content becomes like this. Preferably it is 20 mass parts or less, More preferably, it is 15 mass parts or less. If it is less than 1 part by mass, sufficient vulcanization may not be achieved, and if it exceeds 20 parts by mass, sufficient scorch time may not be ensured.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, kneader, open roll or the like and then vulcanizing. The rubber composition is used for a tread of a high-performance wet tire.

The high-performance wet tire of the present invention is produced by a normal method using the rubber composition.
That is, the rubber composition containing the above components is extruded in accordance with the shape of the tread at an unvulcanized stage and molded together with other tire members on a tire molding machine by a normal method. Form a vulcanized tire. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire. In addition, the high-performance wet tire in the present invention is a tire that is particularly excellent in wet grip performance, and is a concept that includes a competition tire used in a competition vehicle. The high-performance wet tire is suitable for competition tires such as races, and particularly for competition wet tires used on wet road surfaces.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
High TgSBR: Asaprene 303 manufactured by Asahi Kasei Corporation (vinyl content: 30% by mass, styrene content: 46% by mass, Tg: -34 ° C.)
SBR: Toughden 3830 manufactured by Asahi Kasei Co., Ltd. (vinyl content: 35% by mass, styrene content: 33% by mass, Tg: −39 ° C., rubber solid content: 100 parts by mass, oil content: 37.5 parts by mass Contains)
Carbon black: Seast 9 (SAF, N ₂ SA: 142 m ² / g, DBP oil absorption: 115 ml / 100 g) manufactured by Tokai Carbon Co., Ltd.
Silica: Nipsil VN3 manufactured by Tosoh Silica Co., Ltd. (CTAB: 168 m ² / g, DBP: 183 ml / 100 g, N ₂ SA: 177 m ² / g)
Silane coupling agent: Si69 manufactured by Degussa
Aluminum hydroxide: Heidilite H-43 (average primary particle size: 1 μm) manufactured by Showa Denko KK
Hydrogenated styrenic thermoplastic elastomer 1: S.A. manufactured by Asahi Kasei Corporation. O. E. S1611 (hydrogenated block copolymer having a styrene block at both ends and a random copolymer block of styrene and butadiene in the main chain, styrene content: 60% by mass, hydrogenation rate: 100 mol%, Mw : 1.7 × 10 ⁵ , Tg: 9 ° C.)
Hydrogenated styrene-based thermoplastic elastomer 2: S.A. manufactured by Asahi Kasei Corporation. O. E. L609 (hydrogenated block copolymer having a styrene block at both ends and a random copolymer block of styrene and butadiene in the main chain, styrene content: 56 mass%, hydrogenation rate: 35 mol%, Mw : 2.0 × 10 ⁵ , Tg: 19 ° C.)
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Liquid diene polymer: L-SBR-820 manufactured by Kuraray Co., Ltd. (liquid SBR, Mw: 1.0 × 10 ⁴ , styrene content: 45% by mass)
Resin: Escron G-90 (coumarone indene resin) manufactured by Nikkiso Chemical Co., Ltd.
Zinc oxide: Zinc oxide wax manufactured by Mitsui Mining & Smelting Co., Ltd .: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent: Antigen 6C (N-phenyl-N ′-(1,3-dimethyl) -p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. 1: Noxeller DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator 2: Noxeller TOT-N (tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

<Examples and Comparative Examples>
In accordance with the formulation shown in Table 1, compounding materials other than sulfur and a vulcanization accelerator were kneaded using 1.7 L Banbury manufactured by Kobe Steel Co., Ltd. Sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded using an open roll to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was molded into a tread shape, bonded together with other tire members on a tire molding machine, vulcanized at 150 ° C. for 30 minutes, and a test tire (tire size: 215). / 45R17).

The following evaluation was performed about the obtained tire for a test. The results are shown in Table 1.

(Wet grip performance)
The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle was run for 10 laps on a wet asphalt road test course. At that time, the test driver evaluated the stability of control during steering in the sixth to tenth laps, and each index was displayed with Comparative Example 1 as 100 (wet grip performance index). It shows that wet grip performance is so high that a numerical value is large.

(Initial wet grip performance)
The test tire was mounted on a 2000 cc domestic FR vehicle, and the vehicle was run for 10 laps on a wet asphalt road test course. At that time, the test driver evaluated the stability of control during steering in the first to fifth laps, and an index was displayed with Comparative Example 1 as 100 (initial wet grip performance index). It shows that initial wet grip performance is so high that a numerical value is large.

(Grip performance during dry-up)
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, and the vehicle traveled 10 laps on a dry up asphalt road test course. The test driver evaluated the stability of the control during steering at that time, and each index was displayed with Comparative Example 1 as 100 (grip performance index during dry-up). The larger the value, the higher the grip performance on the dry-up road surface.

(Abrasion resistance during dry-up)
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, and the vehicle traveled 10 laps on a dry up asphalt road test course. The remaining groove amount of the tire tread rubber after running was measured and indicated as an index with the remaining groove amount of Comparative Example 1 being 100 (wear resistance index during dry-up). The larger the value, the higher the wear resistance performance on the dry-up road surface.

From Table 1, in Examples where SBR and hydrogenated styrene-based thermoplastic elastomer were respectively blended in predetermined amounts, the initial grip performance and grip performance on the wet road surface, the grip performance on the dry-up road surface and The wear resistance was improved in a well-balanced manner.

Claims (7)

Contains styrene butadiene rubber and hydrogenated styrene thermoplastic elastomer,
A tread rubber composition for high-performance wet tires, wherein the content of the styrene-butadiene rubber is 60 to 97% by mass and the content of the hydrogenated styrene-based thermoplastic elastomer is 3 to 40% by mass in 100% by mass of the rubber component. The tread rubber composition for a high-performance wet tire according to claim 1, wherein a hydrogenation rate of the hydrogenated styrene-based thermoplastic elastomer is 20 to 100 mol%. The hydrogenated styrene-based thermoplastic elastomer has a block having a styrene block at both ends and a block containing at least one conjugated diene selected from the group consisting of butadiene, butylene, and ethylene, and styrene in the main chain. The tread rubber composition for high-performance wet tires according to claim 1 or 2, which is a hydrogenated product of a copolymer. The tread rubber composition for a high-performance wet tire according to any one of claims 1 to 3, wherein the hydrogenated styrene-based thermoplastic elastomer has a weight average molecular weight of 50,000 to 500,000. Containing carbon black, silica, and an inorganic reinforcing agent represented by the following formula,
The content of the carbon black is 10 to 50 parts by mass, the content of the silica is 30 to 100 parts by mass, and the content of the inorganic reinforcing agent is 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component. The tread rubber composition for high-performance wet tires according to any one of claims 1 to 4.
kM ₁ · xSiO _y · zH ₂ O
(Wherein M ₁ is at least one metal selected from the group consisting of Al, Mg, Ti and Ca, an oxide or hydroxide of the metal, k is an integer of 1 to 5, and x is 0 to 0) 10 is an integer, y is an integer of 2 to 5, and z is an integer of 0 to 10.) The tread rubber composition for a high-performance wet tire according to claim 5, wherein the inorganic reinforcing agent is aluminum hydroxide. The high performance wet tire which has a tread produced using the rubber composition in any one of Claims 1-6.