JP6790351B2 - Rubber composition and tires - Google Patents

Description

The present invention relates to a rubber composition and a tire comprising a tread composed of the rubber composition.

The rubber composition for treads of high-performance tires is desired to maintain high steering stability (grip performance) on a dry road surface (dry road surface) from the initial stage to the end of running. That is, it is desired to maintain good grip performance during running as well as excellent initial grip performance.

Conventionally, for the purpose of improving grip performance, a method of blending a tackifier resin in a tread rubber composition has been studied. However, although stable grip performance during running can be obtained to some extent by blending the adhesive resin, on the contrary, the problem that the temperature dependence of hardness increases and the initial grip performance deteriorates, and wear resistance There is a problem of getting worse.

On the other hand, for the purpose of improving the initial grip performance, a method of adding oil and a method of using a resin or a plasticizer having a low softening point in combination are being studied. Although the initial grip performance is improved by these methods, there is a problem that the wear resistance is deteriorated and the grip performance during running is lowered as the temperature of the tread rises.

Patent Document 1 describes a method of combining a low-temperature plasticizer and a resin having a high softening point with a specific styrene-butadiene rubber, but there is still room for improvement in wear resistance and grip performance during running.

Japanese Unexamined Patent Publication No. 2004-137436

An object of the present invention is to provide a rubber composition capable of obtaining stable and high grip performance at the initial stage of running and during running while maintaining wear resistance, and a tire provided with a tread composed of the rubber composition. To do.

As a result of diligent studies, the present inventor has obtained a significant improvement in grip performance by using a styrene-based thermoplastic elastomer in combination with a tack-imparting resin for a diene-based rubber component containing a predetermined amount of carbon black. Since the content of the imparting resin can be reduced, it is possible to achieve both the temperature dependence of hardness and the abrasion resistance, which are the contradictory performances of the tackifier resin, and it is possible to solve the above-mentioned problems. completed.

That is, the present invention
[1] A rubber composition containing a diene-based rubber component, a tackifier resin, a styrene-based thermoplastic elastomer, and carbon black as a reinforcing agent.
A rubber composition having a carbon black content of 50 to 200 parts by mass with respect to 100 parts by mass of a diene rubber component.
[2] The content of the tackifier resin with respect to 100 parts by mass of the diene rubber component is 5 to 70 parts by mass, preferably 10 to 65 parts by mass, more preferably 15 to 60 parts by mass, and contains a styrene-based thermoplastic elastomer. The rubber composition according to the above [1], wherein the amount is 3 to 15 parts by mass, preferably 5 to 14 parts by mass, and more preferably 7 to 13 parts by mass.
[3] The rubber composition according to the above [1] or [2], wherein the content of carbon black with respect to 100 parts by mass of the diene-based rubber component is 80 to 150 parts by mass, preferably 90 to 150 parts by mass.
[4] The rubber composition according to any one of the above [1] to [3], wherein the content of carbon black in the reinforcing agent is 100%.
[5] The rubber composition according to any one of the above [1] to [4], wherein the styrene-based thermoplastic elastomer has a styrene block at the polymer end.
[6] The rubber composition according to any one of the above [1] to [5], wherein the tackifier resin has a softening point of 60 to 170 ° C. and 80 to 150 ° C.
[7] The rubber composition according to any one of the above [1] to [6], which further contains a softening agent.
[8] The rubber composition according to the above [7], wherein the softener contains at least one of oil or a liquid diene rubber, and [9] the rubber composition according to any one of the above [1] to [8]. Concerning high performance tires with a composed tread.

According to the present invention, it is possible to provide a tire having a rubber composition capable of obtaining stable and high grip performance at the initial stage of running and during running while maintaining wear resistance, and a tire having a tread composed of the rubber composition. ..

The rubber composition of the present invention is a rubber composition containing a diene-based rubber component, a tackifier resin, a styrene-based thermoplastic elastomer, and carbon black as a reinforcing agent, and the content of carbon black with respect to 100 parts by mass of the diene-based rubber component. Is 50 to 200 parts by mass.

Examples of the diene rubber that can be used in the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), and ethylene propylene diene rubber. (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR) and the like. These diene rubbers may be used alone or in combination of two or more. Of these, NR, BR, and SBR are preferable, and SBR is more preferable, because grip performance and wear resistance can be obtained in a well-balanced manner.

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), and the like, which are common in the tire industry, can be used. Of these, S-SBR is preferable because it has an excellent balance between grip and wear resistance.

The styrene content of SBR is preferably 20% by mass or more, more preferably 25% by mass or more. By setting the styrene content of SBR to 20% by mass or more, more sufficient grip performance tends to be obtained. The styrene content of SBR is preferably 60% by mass or less, more preferably 50% by mass or less. By setting the styrene content of SBR to 60% by mass or less, deterioration of wear resistance and temperature dependence is suppressed, performance is stable against temperature changes, and more stable grip performance during running tends to be obtained. It is in. The styrene content of SBR in the present specification is a value calculated by ^{1 1} H-NMR measurement.

When SBR is contained, the content of SBR in the diene rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 60% by mass or more. By setting the SBR content to 10% by mass or more, more sufficient heat resistance, grip performance, and wear resistance tend to be obtained. The upper limit of the SBR content is not particularly limited, and is preferably 100% by mass.

Examples of the type of tackifier resin that can be used in the present invention include resins commonly used in conventional rubber compositions for tires such as aromatic petroleum resins. Examples of the aromatic petroleum resin include phenolic resin, kumaron-inden resin, terpene resin, styrene resin, acrylic resin, rosin resin, dicyclopentadiene resin (DCPD resin) and the like. Examples of the phenolic resin include kolesin (registered trademark) (manufactured by BASF) and tackylol (registered trademark) (manufactured by Taoka Chemical Co., Ltd.). Examples of the kumaron-indene resin include Esclon (registered trademark) (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) and neopolymer (manufactured by JX Nippon Oil & Energy Co., Ltd.). Examples of the styrene resin include SYLVATRAXX (registered trademark) 4401 (manufactured by Arizona chemical) and YS resin SX100 (manufactured by Yasuhara Chemical Co., Ltd.). Examples of the terpene resin include SYLVARES (registered trademark) TR7125 (manufactured by Arizona Chemical Co., Ltd.) and YS resin TO125 (manufactured by Yasuhara Chemical Co., Ltd.). The tackifier resin may be used alone or in combination of two or more. Of these, it is preferable to use a phenolic resin, a styrene resin, or a mixture thereof from the viewpoint of balancing grip and wear resistance.

The softening point of the tackifier resin is preferably 60 ° C. or higher, more preferably 80 ° C. or higher. By setting the softening point of the tackifier resin to 60 ° C. or higher, more sufficient stable grip performance during running tends to be obtained. The softening point of the tackifier resin is preferably 170 ° C. or lower, more preferably 150 ° C. or lower. By setting the softening point of the tackifier resin to 170 ° C. or lower, better initial grip performance tends to be obtained. In the present invention, the softening point of the resin is the temperature at which the ball drops when the softening point defined in JIS K 6220-1: 2001 is measured by a ring-ball type softening point measuring device.

The content of the tackifier resin with respect to 100 parts by mass of the diene rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more. By setting the content of the tackifier resin to 5 parts by mass or more, more sufficient grip performance tends to be obtained. The content of the tackifier resin with respect to 100 parts by mass of the diene rubber component is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and further preferably 60 parts by mass or less. By setting the content of the tackifier resin to 70 parts by mass or less, more sufficient wear resistance tends to be obtained.

The styrene-based thermoplastic elastomer is a copolymer having at least one styrene block (hard segment) and at least one elastomer block. Specific examples of the molecular structure of the styrene-based thermoplastic elastomer are not particularly limited, but a molecular structure having a styrene block at one end or both ends and an elastomer block in the other is preferable. Having a styrene block at least at one end tends to provide better grip performance. Further, the styrene-based thermoplastic elastomer preferably has a structure having no styrene block in the main chain portion other than the terminal. With such a structure, the hardness of the rubber in the normal temperature range does not become too high, deterioration of the initial grip performance is suppressed, and better fracture characteristics and wear resistance tend to be obtained.

By containing the styrene-based thermoplastic elastomer, the rubber composition of the present invention can keep the content of the tackifier resin low, thereby sacrificing the temperature dependence of the hardness of the rubber composition and the abrasion resistance. It is not necessary to use the above, and the synergistic effect with the tackifier resin can greatly improve the grip performance during running, especially in the latter half.

As the elastomer block, vinyl-polydiene, polyisoprene, polybutadiene, polyethylene, polychloroprene, poly2,3-dimethylbutadiene and the like are preferably used. As the elastomer block, a hydrogenated one can also be used. When the elastomer block is hydrogenated, the wear resistance tends to be better, which is preferable.

Specific examples of the styrene-based thermoplastic elastomer include styrene-vinylisoprene-styrene triblock copolymer (SIS), styrene-isobutyrene block copolymer (SIB), and styrene-butadiene-styrene triblock copolymer (SBS). ), Styrene-ethylene butene-styrene triblock copolymer (SEBS), styrene-ethylene / propylene-styrene triblock copolymer (SEPS), styrene-ethylene / ethylene / propylene-styrene triblock copolymer (SEEPS) ), Styrene-butadiene butylene-styrene triblock copolymer (SBBS) and the like. The styrene-based thermoplastic elastomer may be used alone or in combination of two or more. Of these, a styrene-vinylisoprene-styrene triblock copolymer is preferable. Preferable examples of such a styrene-vinylisoprene-styrene triblock copolymer include Hybler 5127 manufactured by Kuraray Co., Ltd. Further, Hybler 7311 manufactured by Kuraray Co., Ltd., to which a vinyl isoprene block is hydrogenated, can also be preferably used.

The content of the styrene unit (styrene content) of the styrene-based thermoplastic elastomer is preferably 5% by mass or more, and more preferably 10% by mass or more. By setting the styrene content of the styrene-based thermoplastic elastomer to 5% by mass or more, better grip performance tends to be obtained. The styrene content of the styrene-based thermoplastic elastomer is preferably 30% by mass or less, more preferably 20% by mass or less. By setting the styrene content of the styrene-based thermoplastic elastomer to 30% by mass or less, there is no risk of deteriorating heat generation.

The content of the styrene-based thermoplastic elastomer with respect to 100 parts by mass of the diene-based rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 7 parts by mass or more. By setting the content of the styrene-based thermoplastic elastomer to 3 parts by mass or more, a better grip performance from the initial stage of running to the end of running tends to be obtained, and the content of the styrene-based thermoplastic elastomer is 3% by mass. If it is less than the part, the effect on the grip performance tends to be small. The content of the styrene-based thermoplastic elastomer with respect to 100 parts by mass of the diene-based rubber component is preferably 15 parts by mass or less, more preferably 14 parts by mass or less, and even more preferably 13 parts by mass or less. If the content of the styrene-based thermoplastic elastomer exceeds 15 parts by mass, the wear resistance tends to deteriorate.

Examples of the carbon black include carbon black produced by the oil furnace method, and two or more kinds of carbon blacks having different colloidal characteristics may be used in combination. Specific examples thereof include GPF, HAF, ISAF, and SAF, and among them, SAF is preferable.

The content of carbon black with respect to 100 parts by mass of the diene rubber component is 50 parts by mass or more, preferably 80 parts by mass or more, and more preferably 90 parts by mass or more. If the content of carbon black is less than 50 parts by mass, sufficient wear resistance and grip performance tend not to be obtained. The content of carbon black with respect to 100 parts by mass of the diene rubber component is 200 parts by mass or less, preferably 150 parts by mass or less. If the content of carbon black exceeds 200 parts by mass, the grip performance tends to deteriorate.

Nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably not less than 100 m ² / g, more preferably at least 105m ² / g, more 110m ² / g is more preferred. By setting the nitrogen adsorption specific surface area of carbon black to 100 m ² / g or more, better grip performance tends to be obtained. Further, the nitrogen adsorption specific surface area of the carbon black is preferably 600 meters ² / g or less, more preferably ^{250m 2 / g, 180m 2 /} g or less is more preferred. By setting the nitrogen adsorption specific surface area of carbon black to 600 m ² / g or less, the dispersibility in the rubber composition tends to be excellent, and better wear resistance tends to be obtained. The nitrogen adsorption specific surface area of carbon black is determined in accordance with JIS K 6217-2: 2001.

Oil oil absorption of the carbon black (DBP) is preferably at least 50 cm ^3/100 g, more preferably at least 70cm ³ / 100g. By the DBP of the carbon black with 50 cm ^3/100 g or more, it tends to better abrasion resistance. Further, DBP of the carbon black is preferably 250 cm ^3/100 g or less, 200 cm ^3/100 g and more preferably less, more preferably less 135 cm ^3/100 g. By the DBP of the carbon black less 250 cm ^3/100 g, tend to better grip performance can be obtained. The carbon black DBP is measured in accordance with JIS K 6217-4: 2008.

In addition to the above components, the rubber composition of the present invention contains a compounding agent generally used in the rubber industry, for example, a reinforcing agent other than carbon black, a softener, zinc oxide, stearic acid, various antioxidants, and a wax. , Vulcanization agent, vulcanization accelerator and the like can be appropriately blended.

As the reinforcing agent other than carbon black, silica, calcium carbonate, alumina, clay, talc and the like can be arbitrarily selected and used from those commonly used in the conventional rubber industry, especially in rubber compositions for tires. It is preferable that the reinforcing agent other than black is not contained and the content of carbon black in the reinforcing agent is 100%.

In the present invention, it is preferable to contain a softening agent from the viewpoint of better initial grip performance, better stable grip performance during running, and the like. The softening agent is not particularly limited, and examples thereof include oils and liquid diene-based polymers. The softener may be used alone or in combination of two or more. It is preferable to use oil and a liquid diene polymer in combination from the viewpoint of good grip performance and wear resistance.

Examples of the oil include process oils such as paraffin-based process oils, aroma-based process oils, and naphthen-based process oils. Of these, aroma-based process oils are preferable because of their good grip performance.

When oil is contained, the content of the diene rubber component with respect to 100 parts by mass is preferably 15 parts by mass or more, more preferably 30 parts by mass or more. By setting the oil content to 15 parts by mass or more, the effect of adding the oil tends to be satisfactorily obtained. The content of the oil with respect to 100 parts by mass of the diene rubber component is preferably 85 parts by mass or less, more preferably 80 parts by mass or less. By setting the oil content to 85 parts by mass or less, better wear resistance tends to be obtained. The oil content in the present specification also includes the oil content contained in the oil spread rubber.

The liquid diene polymer means a diene polymer in a liquid state at room temperature (25 ° C.), for example, a liquid styrene-butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), and a liquid isoprene weight. Examples thereof include coalescence (liquid IR) and liquid styrene isoprene copolymer (liquid SIR). The liquid diene polymer may be used alone or in combination of two or more. Of these, liquid SBR is preferable because it provides a good balance between better wear resistance and stable grip performance during running.

The weight average molecular weight (Mw) of the liquid diene polymer is preferably 1.0 × 10 ³ or more, and more preferably 3.0 × 10 ³ or more. With a weight-average molecular weight of the liquid diene polymer (Mw) 1.0 × 10 ³ or more, suppressing a decrease in abrasion resistance and fracture properties tend to be secured sufficient durability. The weight average molecular weight of the liquid diene polymer (Mw) of, preferably 2.0 × at 10 ⁵ or less and more preferably 1.5 × 10 ⁴ or less. By weight average molecular weight of the liquid diene polymer (Mw) and 2.0 × 10 ⁵ or less, productivity too high viscosity of the polymerization solution tends to be able to prevent the worse. The weight average molecular weight (Mw) of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

When the liquid diene polymer is contained, the content of the diene rubber component with respect to 100 parts by mass is preferably 5 parts by mass or more, more preferably 7 parts by mass or more. By setting the content of the liquid diene polymer to 5 parts by mass or more, more sufficient grip performance tends to be obtained. The content of the liquid diene polymer with respect to 100 parts by mass of the diene rubber component is preferably 100 parts by mass or less, more preferably 40 parts by mass or less. By setting the content of the liquid diene polymer to 100 parts by mass or less, deterioration of wear resistance tends to be prevented.

When a plurality of softeners are used in combination, the total content of the softener with respect to 100 parts by mass of the diene rubber component is preferably 30 parts by mass or more, more preferably 40 parts by mass or more. By setting the total content of the softener to 30 parts by mass or more, better grip performance tends to be obtained. The total content of the softener with respect to 100 parts by mass of the diene rubber component is preferably 150 parts by mass or less, more preferably 140 parts by mass or less. By setting the total content of the softener to 150 parts by mass or less, better wear resistance tends to be obtained.

The zinc oxide is not particularly limited, and examples thereof include those conventionally used in the rubber industry such as tires. When zinc oxide is contained, the content of the diene-based rubber component with respect to 100 parts by mass is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. By setting the zinc oxide content to 0.5 parts by mass or more, the effects of the present invention tend to be more preferably obtained. The content of zinc oxide with respect to 100 parts by mass of the diene rubber component is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. By setting the zinc oxide content to 10 parts by mass or less, the effects of the present invention tend to be more preferably obtained.

Stearic acid, various anti-aging agents, waxes and the like are not particularly limited, and can be arbitrarily selected and used from those conventionally used in the rubber industry.

The vulcanizing agent is not particularly limited, and general ones in the rubber industry can be used, but those containing a sulfur atom are preferable, and examples thereof include powdered sulfur, precipitated sulfur, and insoluble sulfur. Powdered sulfur is particularly preferably used.

Examples of the vulcanization accelerator include sulfenamide-based, thiazole-based, thiuram-based, and guanidine-based vulcanization accelerators. The vulcanization accelerator may be used alone or in combination of two or more. Of these, thiazole-based and thiuram-based vulcanization accelerators are preferable.

Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like, and among them, from the viewpoint of wear resistance. Di-2-benzothiazolyl disulfide is preferred. Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetrabenzyl thiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N), and the like, and among them, wear resistance performance. From this point of view, TOT-N is preferable.

When the vulcanization accelerator is contained, the content of the diene rubber component with respect to 100 parts by mass is preferably 1 part by mass or more, and more preferably 3 parts by mass or more. By setting the content of the vulcanization accelerator to 1 part by mass or more, a sufficient vulcanization rate is obtained, and there is a tendency that better grip performance and wear resistance can be obtained. The content of the vulcanization accelerator with respect to 100 parts by mass of the diene rubber component is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less. By setting the content of the vulcanization accelerator to 15 parts by mass or less, the occurrence of blooming tends to be prevented, and better grip performance and wear resistance tend to be obtained.

As a method for producing the rubber composition of the present invention, a known method can be used. For example, the rubber composition can be produced by kneading each of the above components with a Banbury mixer, a kneader, an open roll, or the like, and then vulcanizing.

The rubber composition of the present invention can be used not only for tire applications such as tire treads, under treads, carcasses, sidewalls and beads, but also for anti-vibration rubbers, belts, hoses and other industrial products. Among them, the rubber composition of the present invention is preferably used for tire members, particularly treads, because it is excellent in grip performance during running from the beginning to the end of running while maintaining wear resistance, and the tread is When the tread has a two-layer structure consisting of a cap tread and a base tread, it is preferably used for the cap tread. Here, the cap tread is a surface layer in a tread having a two-layer structure, and the base tread is an inner layer.

The tire of the present invention can be produced by a usual method using the rubber composition of the present invention. That is, the rubber composition of the present invention is extruded according to the shape of the tread of the tire at the unvulcanized stage, bonded together with other tire members on a tire molding machine, and molded by a usual method. The tire of the present invention can be manufactured by forming an unvulcanized tire and heating and pressurizing the unvulcanized tire in a vulcanizer.

Further, the tire of the present invention is preferably a high-performance tire, and is preferably applied to a high-performance dry tire. The high-performance tire in the present specification is a tire having particularly excellent grip performance (particularly, dry grip performance), and is a concept including a competition tire used in a competition vehicle. This high-performance tire can be suitably used for competition tires such as races, particularly for competition dry tires used on dry road surfaces.

Although the present invention will be described based on examples, the present invention is not limited to the examples.

Hereinafter, various chemicals used in Examples and Comparative Examples are collectively shown.
SBR: Toughden 3830 manufactured by Asahi Kasei Corporation (S-SBR, styrene content: 33% by mass, vinyl bond amount: 34% by mass, oil development containing 37.5 parts by mass of oil with respect to 100 parts by mass of rubber solids Rubber)
Thermoplastic Elastomer 1: Hybler 5127 manufactured by Kuraray Co., Ltd. (Styrene content: 20%)
Thermoplastic Elastomer 2: Hybler 7311 manufactured by Kuraray Co., Ltd. (Styrene content: 12%, vinyl-polyisoprene block hydrogenation)
Adhesive-imparting resin 1: BASF's Collesin (registered trademark) (phenolic resin, softening point: 145 ° C)
Adhesive-imparting resin 2: YS resin SX100 manufactured by Yasuhara Chemical Co., Ltd. (styrene resin, softening point: 100 ° C.)
Carbon black: Seast 9 manufactured by Toyo Carbon Co., Ltd. (SAF, N ₂ SA: 142m ² / g, DBP: 115cm ³ / 100g)
Silica: Premium 200MP (N ₂ SA: 200m ² / g) manufactured by Rhodia.
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA.
Liquid diene polymer: L-SBR820 manufactured by Kuraray Co., Ltd. (liquid SBR, styrene content: 22%, weight average molecular weight (Mw): 8500)
Oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Zinc oxide: Zinc oxide type 2 stearic acid manufactured by Mitsui Kinzoku Mining Co., Ltd .: Stearic acid "Camellia" manufactured by NOF CORPORATION
Anti-aging agent: Antigen (registered trademark) 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunknock (registered trademark) N manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Sulfur: Powdered sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. 1: Noxeller (registered trademark) DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization Accelerator 2: Noxeller (registered trademark) TOT-N (Tetrakis (2-ethylhexyl) thiuram disulfide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

Examples 1-9 and Comparative Examples 1-8
According to the formulation shown in Table 1, the above various chemicals (excluding sulfur and vulcanization accelerator) are kneaded for 10 minutes at a discharge temperature of 150 ° C. using a 16L Banbury mixer manufactured by Kobe Steel, Ltd. Got Next, the obtained kneaded product, sulfur, and vulcanization accelerator were kneaded with a Banbury mixer at a discharge temperature of 90 ° C. for 8 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded into a tread shape, bonded together with other tire members on a tire molding machine, vulcanized at 170 ° C. for 25 minutes, and tested tire (tire size: 215 /). 45R17) was manufactured. The obtained test tires were evaluated as follows. The results are shown in Table 1.

<Grip performance>
The test tires were attached to all wheels of a domestic FR vehicle (displacement 2000cc), and the actual vehicle ran 10 laps on a test course on a dry asphalt road surface of 3.7km per lap. At that time, the test driver evaluated the stability of the control during steering, and the comparative example 4 was set as 100 and displayed as an exponential notation. The larger the value, the higher the grip performance on the dry road surface. In addition, the initial grip performance was evaluated in the 1st to 3rd weeks, and the latter half of the grip performance was evaluated in the 4th to 10th weeks.

<Abrasion resistance>
The amount of remaining groove of the tire tread rubber after the above-mentioned grip performance test was measured (15 mm when new). The larger the amount of remaining grooves, the better the wear resistance. The remaining groove amount of Comparative Example 4 was set as 100 and displayed as an exponential notation. The larger the value, the higher the wear resistance.

From the results in Table 1, the rubber composition of the present invention containing a predetermined amount of carbon black with respect to the diene-based rubber component, the styrene-based thermoplastic elastomer, the tackifier resin, and the diene-based rubber component has high grip performance at the initial stage of running. It can be seen that the balance of stability can be significantly improved throughout the run.

Claims (9)

A rubber composition containing a diene-based rubber component, a tackifier resin, a styrene-based thermoplastic elastomer, and carbon black as a reinforcing agent.
The content of carbon black with respect to 100 parts by mass of the diene rubber component is 50 to 200 parts by mass.
The diene rubber is at least one selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, styrene isoprene butadiene rubber, ethylene propylene diene rubber, chloroprene rubber, acrylonitrile butadiene rubber and butyl rubber.
The tackifier resin is at least one selected from the group consisting of phenolic resin, kumaron-inden resin, styrene resin, acrylic resin, rosin resin and dicyclopentadiene resin.
Styrene-based thermoplastic elastomers are styrene-vinylisoprene-styrene triblock copolymer, styrene-isobutyrene block copolymer, styrene-ethylene / butene-styrene triblock copolymer, styrene-ethylene / propylene-styrene triblock copolymer, a styrene - ethylene-ethylene-propylene - styrene triblock copolymer and a styrene - butadiene butylene - is at least one selected from styrene triblock copolymer or Ranaru group scan styrene-based thermoplastic elastomer A rubber composition having a styrene unit content of 5 to 20% by mass. The rubber composition according to claim 1, wherein the content of the tackifier resin is 5 to 70 parts by mass with respect to 100 parts by mass of the diene-based rubber component, and the content of the styrene-based thermoplastic elastomer is 3 to 15 parts by mass. The rubber composition according to claim 1 or 2, wherein the content of carbon black with respect to 100 parts by mass of the diene-based rubber component is 80 to 150 parts by mass. The rubber composition according to any one of claims 1 to 3, wherein the content of carbon black in the reinforcing agent is 100%. The rubber composition according to any one of claims 1 to 4, wherein the diene-based rubber is a solution-polymerized styrene-butadiene rubber. The rubber composition according to any one of claims 1 to 5, wherein the softening point of the tackifier resin is 60 to 170 ° C. Further contains a softener,
The rubber composition according to any one of claims 1 to 6, wherein the softener is at least one of an oil or a liquid diene polymer. The rubber composition according to any one of claims 1 to 7, wherein the content of the tackifier resin with respect to 100 parts by mass of the diene rubber component is 15 to 70 parts by mass. A tire having a tread composed of the rubber composition according to any one of claims 1 to 8.