JP2013227400A - Rubber composition for tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a tire tread, regulated so that low rolling resistance, steering stability and processability may be improved more than conventional levels.SOLUTION: A rubber composition for a tire tread is obtained by compounding ≥3 pts.wt. of a modified terpene resin, 90-120 pts.wt. of silica and carbon black with 100 pts.wt. of diene rubber containing ≥60 wt.% of a modified S-SBR 1, and regulating so that the content of a terminal-modified and solution-polymerized styrene-butadiene rubber including the modified S-SBR 1 may be ≥90 wt.%, the functional group of the modified S-SBR 1 may have reactivity with a silanol group, the content of a styrene unit may be 30-45 wt.%, the glass transition temperature may be from -40 to -10°C, the specific surface area of the silica measured by nitrogen adsorption may be 140-180 m/g, the CTAB specific surface area may be 140-170 m/g, the proportion of the silica based on the total amount (B) of the silica and the carbon black may be ≥90 wt.%, the total amount (A) of the modified terpene resin and the oil amount may be ≤30 pts.wt., and the difference between the total amount (B) and the total amount (A) may be ≥75 pts.wt.

Description

  The present invention relates to a rubber composition for a tire tread, and more particularly to a rubber composition for a tire tread that is improved in low rolling resistance, steering stability, and processability.

  In recent years, the labeling (display method) system has been started for pneumatic tires for passenger cars, and it is required to achieve both low rolling resistance and wet grip performance at a higher level. This flow is no exception for high performance tires (UHPT) in which steering stability including dry grip performance is most important, and it is necessary to improve low rolling resistance while ensuring excellent steering stability.

  In a pneumatic tire (UHPT) that emphasizes handling stability, particularly dry grip performance, it is necessary to increase the rubber hardness of the rubber composition that constitutes the tread portion, and generally a composition that contains a large amount of carbon black. ing. However, when a large amount of carbon black is blended, the rolling resistance increases. Therefore, blending silica instead may lower the rolling resistance and improve the fuel efficiency. On the other hand, when carbon black is replaced with silica, the rubber hardness decreases. For this reason, it is conceivable to secure rubber hardness by reducing the amount of softener component such as oil in the rubber composition. However, if the amount of the softener component is reduced, there is a problem that the viscosity of the rubber composition increases and the processability deteriorates.

  On the other hand, in order to increase the reinforcing performance by adding silica to rubber, it is necessary to reduce the particle diameter of silica or increase the compounding amount. However, since silica with a small particle size has a strong cohesive force, it is difficult to disperse it well in a diene rubber, and when a large amount of silica is added, the viscosity of the rubber composition increases and the processability deteriorates. there were.

  Patent Document 1 improves rolling dispersibility (tan δ at 60 ° C.) by improving the dispersibility of silica by using a rubber composition in which silica is blended with terminal-modified solution-polymerized styrene butadiene rubber whose terminal is modified with polyorganosiloxane or the like. Propose that. However, although this rubber composition has an effect of reducing rolling resistance, there is a problem that the viscosity of the rubber composition increases and processability deteriorates.

  For this reason, it has been difficult to improve the low rolling resistance while maintaining excellent handling stability and workability.

JP 2009-91498 A

  An object of the present invention is to provide a rubber composition for a tire tread in which low rolling resistance, steering stability and processability are improved to a level higher than that of the conventional level.

The rubber composition for a tire tread of the present invention that achieves the above object is obtained by adding a modified terpene resin to 100 parts by weight of a diene rubber containing 60% by weight or more of a terminal-modified solution-polymerized styrene butadiene rubber (modified S-SBR1). A rubber composition in which 90 to 120 parts by weight of silica and 90% by weight of silica and carbon black are blended, and the terminal-modified solution-polymerized styrene butadiene rubber containing the modified S-SBR1 is contained in 100% by weight of the diene rubber. The functional group of the modified S-SBR1 is reactive with silanol groups on the silica surface, the styrene unit content is 30 to 45% by weight, and the glass transition temperature is -40 ° C to- with a 10 ° C., the nitrogen adsorption specific surface area of the silica is 140~180m ² / g, CTAB specific surface area of 140~170m ² / g der The ratio of silica to the total amount (B) of the silica and carbon black is 90% by weight or more, and the total amount (A) of the modified terpene resin and the amount of oil contained in the rubber composition is 30 parts by weight. Hereinafter, the difference between the total amount (B) and the total amount (A) is 75 parts by weight or more.

  The rubber composition for a tire tread of the present invention is formulated with a high ratio of silica so that the silica ratio with respect to the total amount (B) of silica and carbon black is 90% by weight or more, and the modified terpene resin and rubber composition The total amount of oil (A) in the product is 30 parts by weight or less, and the difference between these total amount (B) and the total amount (A) is 75 parts by weight or more, so the rubber hardness is increased and excellent handling stability is achieved. At the same time, the rolling resistance can be kept low. Further, the silica is limited to those having specific particle properties, has a functional group reactive with silanol groups on the silica surface, has a styrene unit content of 30 to 45% by weight, and a glass transition temperature of -40. Since the terminal-modified solution-polymerized styrene butadiene rubber containing 60% by weight or more of modified S-SBR1 having a temperature of -10 ° C to 90 ° C is contained by 90% by weight or more, the affinity between silica and rubber is increased, and the dispersibility of silica is increased. Therefore, the rolling resistance can be kept low, and at the same time, the deterioration of workability can be suppressed despite the small total amount (A) of the oil amount in the modified terpene resin and the rubber composition. Further, the content of terminally modified solution-polymerized styrene butadiene rubber containing 60% by weight or more of modified S-SBR1 having a styrene unit content of 30 to 45% by weight and a glass transition temperature of −40 ° C. to −10 ° C. is 90% by weight or more. In addition, since the modified terpene resin is also blended, excellent grip performance can be secured.

  The functional group of the modified S-SBR includes a hydroxyl group-containing polyorganosiloxane structure, an alkoxysilyl group, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, an imino group, an epoxy group, an amide group, a thiol group, and an ether group. It is preferably at least one selected, and is excellent in reactivity with silanol groups on the silica surface.

  The diene rubber preferably contains the modified S-SBR1 and other terminal-modified solution-polymerized styrene butadiene rubber (modified S-SBR2). Thereby, the balance with the abrasion resistance of the rubber composition can be improved.

  The pneumatic tire using the rubber composition for a tire tread of the present invention can improve the low rolling resistance, the steering stability and the workability from the conventional level.

  In the rubber composition for a tire tread of the present invention, the rubber component is made of a diene rubber, and 90% by weight or more of the rubber component is terminal-modified solution-polymerized styrene butadiene rubber (hereinafter referred to as “modified S-SBR”). . The diene rubber can contain 10% by weight or less of other diene rubbers excluding the modified S-SBR. Examples of other diene rubbers include natural rubber, isoprene rubber, butadiene rubber, unmodified solution polymerization or emulsion polymerization styrene butadiene rubber, terminal modified emulsion polymerization styrene butadiene rubber, butyl rubber, propylene-ethylene-diene rubber, and the like. be able to. Of these, natural rubber, emulsion polymerized styrene butadiene rubber, unmodified solution polymerized styrene butadiene rubber, butadiene rubber, natural rubber, emulsion polymerized styrene butadiene rubber, and unmodified solution polymerized styrene butadiene rubber are preferred. For example, wear resistance can be improved by blending butadiene rubber. Further, by blending the emulsion-polymerized styrene butadiene rubber, the rubber strength can be increased and the steering stability of the tire can be increased.

  The content of the modified S-SBR is 90% by weight or more, preferably 92 to 100% by weight in 100% by weight of the diene rubber. By making the content of the modified S-SBR 90% by weight or more, it has good affinity with silica and excellent dispersibility.

  In the rubber composition of the present invention, the modified S-SBR must be a terminally modified solution-polymerized styrene butadiene rubber (hereinafter referred to as “modified S-SBR1”) in which the styrene unit content and the glass transition temperature (Tg) are specified. To include. The content of the modified S-SBR1 is 60% by weight or more, preferably 65 to 100% by weight in 100 parts by weight of the diene rubber. By setting the content of the modified S-SBR1 within such a range, the dispersibility of silica can be improved to reduce rolling resistance, and the dry grip performance of the tread rubber composition can be improved.

  The modified S-SBR1 has a styrene unit content of 30 to 45% by weight, preferably 35 to 45% by weight. If the styrene unit content of the modified S-SBR1 is less than 30% by weight, the grip performance is undesirably lowered. On the other hand, when the styrene unit content of the modified S-SBR1 exceeds 45% by weight, fuel efficiency and wear performance are deteriorated. The styrene unit content of the modified S-SBR is measured by infrared spectroscopic analysis (Hampton method).

  The glass transition temperature (Tg) of the modified S-SBR1 is −40 ° C. to −10 ° C., preferably −35 ° C. to −15 ° C. If the Tg of the modified S-SBR1 is lower than -40 ° C, the grip performance is lowered, which is not preferable. Moreover, when Tg of modified S-SBR1 is higher than −10 ° C., fuel efficiency and wear performance are deteriorated, which is not preferable. The glass transition temperature (Tg) of the modified S-SBR1 is a temperature at the midpoint of the transition region by measuring a thermogram by differential scanning calorimetry (DSC) at a heating rate of 20 ° C./min. Moreover, when modified | denatured S-SBR is an oil-extended article, it is set as the glass transition temperature of modified | denatured S-SBR in the state which does not contain an oil-extended component (oil).

  In the present invention, modified S-SBR and modified S-SBR1 are solution-polymerized styrene butadiene rubbers in which both or one of the molecular ends is modified with a functional group having reactivity with a silanol group on the silica surface. The functional group that reacts with the silanol group is preferably a hydroxyl group-containing polyorganosiloxane structure, alkoxysilyl group, hydroxyl group, aldehyde group, carboxyl group, amino group, imino group, epoxy group, amide group, thiol group, ether group At least one selected from the group consisting of: Of these, a hydroxyl group-containing polyorganosiloxane structure, an alkoxysilyl group, and a hydroxyl group are more preferred.

  The modified S-SBR can contain other modified polymerized styrene butadiene rubber (hereinafter referred to as “modified S-SBR2”) other than the modified S-SBR1 and the modified S-SBR1 described above. The modified S-SBR2 satisfies at least one requirement that the styrene unit content is 10% by weight or more and less than 30% by weight, or that the Tg is −80 ° C. or more and less than −40 ° C. Modified S-SBR2 is an optional component, and the upper limit of the amount is 40% by weight or less in 100% by weight of diene rubber. By blending the modified S-SBR2, the wear resistance of the rubber composition for tread can be improved.

  In the present invention, the balance between low rolling resistance and wet grip performance can be improved by blending the modified terpene resin. Examples of the modified terpene resin include aromatic modification obtained by copolymerizing terpenes such as α-pinene, β-pinene, dipentene, limonene, camphene and aromatic vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene. A terpene resin can be illustrated. As the modified terpene resin, for example, commercially available products such as YS resin TO-125, TO-115, TO-105, TO-105, TO-85 and TR-105 manufactured by Yasuhara Chemical Co., Ltd. can be used.

  The blending amount of the modified terpene resin is 3.0 parts by weight or more, preferably 5.0 to 20.0 parts by weight with respect to 100 parts by weight of the diene rubber, and the total amount (A) with the amount of oil in the rubber composition. Is 30 parts by weight or less. When the amount of the modified terpene resin is less than 3.0 parts by weight, the wet grip performance cannot be sufficiently increased. On the other hand, when the total amount (A) of the modified terpene resin and the oil in the rubber composition exceeds 30 parts by weight, the rubber hardness of the rubber composition is insufficient, and the steering stability is lowered.

  Here, the oil in the rubber composition refers to oil components such as softeners and plasticizers added at the time of compounding the rubber composition, modified S-SBR1, other modified S-SBR, and other diene rubbers. The oil-extended component (oil) contained. Examples of the softening agent include paraffinic process oil, naphthenic process oil, and aromatic process oil. Here, the aromatic process oil includes a highly aromatic oil (TDAE, SRAE, MES) in which a polycyclic aromatic compound (PCA) component is controlled to be less than 3% by weight. However, the oil component does not include wax, processing aid, and anti-aging agent.

The rubber composition for a tire tread of the present invention contains silica and carbon black having specific particle properties. By blending carbon black, the rigidity of the rubber is increased to ensure dry grip performance. In addition, the wear resistance of the rubber composition is ensured. By adding silica, the exothermic property of the rubber composition is suppressed, and the rolling resistance when the tire is formed is reduced. In particular, by blending silica having specific particle properties such that the nitrogen adsorption specific surface area is 140 to 180 m ² / g and the CTAB specific surface area is 140 to 170 m ² / g, the amount of oil in the rubber composition and the modified terpene resin Even when the blending amount is limited and the rubber hardness is increased to ensure the handling stability, the processability of the rubber composition can be sufficiently ensured.

  In the present invention, the amount of silica is 90 to 120 parts by weight, preferably 100 to 115 parts by weight, based on 100 parts by weight of the diene rubber. If the amount of silica is less than 90 parts by weight, the effect of reducing rolling resistance when tires are obtained by reducing the heat build-up of the rubber composition cannot be obtained sufficiently. If the amount of silica exceeds 120 parts by weight, the rubber viscosity increases and the processability deteriorates.

  The ratio of silica to the total amount (B) of silica and carbon black is 90% by weight or more, preferably 90 to 98% by weight. When the ratio of silica is less than 90% by weight, the rolling resistance cannot be sufficiently reduced. Here, the compounding amount of carbon black is such that the silica ratio with respect to the total amount (B) of silica and carbon black is 90% by weight or more, and the compounding amount of silica with respect to 100 parts by weight of the diene rubber is 90 to 120 parts by weight. It is decided from that.

  In the present invention, the difference obtained by subtracting the total amount (A) of the modified terpene resin and the amount of oil contained in the rubber composition from the total amount (B) of silica and carbon black is 75 parts by weight or more, preferably 80 to 90 parts. It shall be a weight part. Thus, the difference between the total amount (B) of silica and carbon black and the total amount (A) of the modified terpene resin and the oil component was 75 parts by weight or more, and the total amount of the modified terpene resin and the oil component. By limiting (A) to 30 parts by weight or less, rubber hardness can be maintained at a high level and excellent dry grip performance can be ensured.

The silica used in the present invention has a nitrogen adsorption specific surface area of 140 to 180 m ² / g, preferably 150 to 175 m ² / g. When the nitrogen adsorption specific surface area of silica is less than 140 m ² / g, the reinforcing property to the rubber composition is insufficient and the steering stability is insufficient. Moreover, when the nitrogen adsorption specific surface area of a silica exceeds 180 m < ² > / g, the dispersibility of the silica with respect to modified S-SBR will fall, and the workability of a rubber composition will deteriorate. In addition, the nitrogen adsorption specific surface area of a silica shall be calculated | required based on JISK6217-2.

Silica has a CTAB specific surface area of 140 to 170 m ² / g, preferably 150 to 165 m ² / g. When the CTAB of silica is less than 140 m ² / g, the reinforcing property for the rubber composition is insufficient and the steering stability is insufficient. On the other hand, if the CTAB of silica exceeds 170 m ² / g, the dispersibility of the silica with respect to the modified S-SBR is lowered, so that the processability of the rubber composition is deteriorated. In addition, CTAB of a silica shall be calculated | required based on JISK6217-3.

  The silica used by this invention should just be a silica which has the characteristic mentioned above, and can be suitably selected from what was manufactured. Moreover, you may manufacture so that it may have the characteristic mentioned above by the normal method. As the type of silica, for example, wet method silica, dry method silica, or surface-treated silica can be used.

  In the rubber composition of the present invention, it is preferable to blend a silane coupling agent together with silica, so that the dispersibility of silica can be improved and the reinforcement to styrene butadiene rubber can be further enhanced. The silane coupling agent is preferably added in an amount of 3 to 15% by weight, more preferably 5 to 12% by weight, based on the amount of silica. When the silane coupling agent is less than 3% by weight of the silica weight, the effect of improving the dispersibility of silica cannot be sufficiently obtained. On the other hand, when the silane coupling agent exceeds 15% by weight, the silane coupling agents are condensed with each other, and a desired effect cannot be obtained.

  Although it does not restrict | limit especially as a silane coupling agent, A sulfur containing silane coupling agent is preferable, for example, bis- (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide. , 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, and the like.

  The rubber composition for a tire tread of the present invention can increase the rubber strength by blending a filler other than silica and carbon black. Examples of such fillers include clay, mica, talc, calcium carbonate, aluminum hydroxide, and aluminum oxide.

  In addition to the fillers described above, the tire tread rubber composition is generally a tire tread rubber composition such as a vulcanization or crosslinking agent, a vulcanization accelerator, an anti-aging agent, a plasticizer, and a processing aid. Various additives to be used can be blended, and such additives can be kneaded by a general method to form a rubber composition, which can be used for vulcanization or crosslinking. As long as the amount of these additives is not contrary to the object of the present invention, a conventional general amount can be used. Such a rubber composition can be produced by mixing each of the above components using a known rubber kneading machine, for example, a Banbury mixer, a kneader, a roll or the like.

  The rubber composition for a tire tread of the present invention can be suitably used for a pneumatic tire. Pneumatic tires using rubber compositions with excellent processability can be manufactured stably with high quality, and they have low rolling resistance and excellent fuel efficiency, as well as dry handling stability and wetness. Excellent handling stability.

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

  16 kinds of rubber compositions for tire treads (Examples 1 to 4 and Comparative Examples 1 to 12) having the composition shown in Tables 1 and 2 are combined with the compounding agents shown in Table 3 as sulfur and vulcanization accelerators. The master batch was prepared by kneading with an open roll after adding sulfur and a vulcanization accelerator to the master batch which was kneaded for 5 minutes with a 1.8 L closed mixer and discharged. In Tables 1 and 2, modified S-SBR1a and SBR contain 37.5 parts by weight of oil-extended oil, and modified S-SBR1b contains 25 parts by weight of oil-extended oil. Along with the blending amount, each SBR net blending amount excluding the oil-extended oil is shown in parentheses. Further, the total amount of the oil-extended oil and the post-added oil contained in these SBRs is shown in the “total amount (A)” column. The total amount of silica and carbon black is shown in the column “Total amount (B)”, and the difference between the total amount (B) and the total amount (A) is shown in the column “Difference (B) − (A)”. Furthermore, the ratio of silica to the total amount (B) of silica and carbon black is shown in the column “Silica ratio”. Moreover, the amount of the compounding agent described in Table 3 is shown in parts by weight with respect to 100 parts by weight (net amount of rubber) of the diene rubber described in Tables 1 and 2.

  The Mooney viscosity of the obtained 16 types of rubber compositions for tire treads was measured by the method shown below and used as an index of workability.

Processability: Mooney viscosity (ML _{1 + 4} )
In accordance with JIS K6300, the obtained rubber composition was subjected to a Mooney viscometer using an L-shaped rotor (38.1 mm diameter, 5.5 mm thickness), preheating time 1 minute, rotor rotation time 4 minutes, 100 The measurement was performed under the conditions of 2 ° C. and ° C. The obtained results are shown in Tables 1 and 2 as an index with the value of Comparative Example 1 as 100. The smaller the index, the smaller the rubber viscosity and the better the workability.

  The obtained 16 kinds of tire tread rubber compositions were press vulcanized at 160 ° C. for 25 minutes in a mold having a predetermined shape to prepare a vulcanized rubber sample, and tan δ (60 ° C.) by the method described below. Was used as an index of rolling resistance.

tan δ (60 ° C)
Using the viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., tan δ (60 ° C.) of the obtained vulcanized rubber sample was subjected to conditions of an initial strain of 10%, an amplitude of ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. Measured with The obtained results are shown in the “Rolling resistance” column of Tables 1 and 2 as an index with Comparative Example 1 as 100. The smaller the rolling resistance index, the lower the heat generation, the lower the rolling resistance when used in a tire, and the better the fuel efficiency.

  Next, four pneumatic tires having a tire size of 225 / 50R17 were manufactured by using the above-described 16 types of rubber compositions for tire treads in the tread portion. The steering stability (wet steering stability and dry steering stability) of the obtained 16 types of pneumatic tires was evaluated by the following methods.

Wet handling stability The obtained pneumatic tire is mounted on a wheel with a rim size of 7 x J, mounted on a 2.5 liter class domestic test vehicle, and on a wet road surface by three specialized panelists under the condition of air pressure of 230 kPa. It was performed on a test course of 1.2km per lap, and the driving performance, braking performance, steering wheel response, and controllability during maneuvering were comprehensively evaluated and scored using a 10-point method. The obtained results are shown in the column of “Wet Steering Stability” in Tables 1 and 2 as an index with the value of Comparative Example 1 as 100. The larger this index, the better the wet handling stability.

Dry handling stability The obtained pneumatic tire is assembled to a wheel with a rim size of 7 x J, mounted on a domestic 2.5-liter class test vehicle, and a real road run by three professional panelists under the condition of air pressure 230 kPa It was performed on a test course of 2.6 km per lap, and the steering stability at that time was scored by a 10-point method based on sensitive evaluation by three specialized panelists. The obtained results are shown in the “Dry handling stability” column of Tables 1 and 2 as an index with the value of Comparative Example 1 as 100. The larger this index, the better the dry handling stability.

The types of raw materials used in Tables 1 and 2 are shown below.
Modified S-SBR1a: solution-polymerized styrene butadiene rubber having a hydroxyl group at the terminal, Toughden E581 manufactured by Asahi Kasei Chemicals, styrene unit content of 37% by weight, glass transition temperature of −27 ° C., oil relative to 100 parts by weight of rubber component Oil-extended and modified S-SBR1b containing 37.5 parts by weight: solution-polymerized styrene butadiene rubber having a hydroxyl group-containing polyorganosiloxane structure at the terminal, NS570 manufactured by ZEON Corporation, styrene unit content of 43% by weight, glass transition Oil-extended and modified S-SBR2a containing 25 parts by weight of oil with respect to 100 parts by weight of rubber component at a temperature of -25 ° C .: solution-polymerized styrene butadiene rubber having a hydroxyl group-containing polyorganosiloxane structure at the terminal, Nipol manufactured by Nippon Zeon NS616, styrene unit content is 23 layers %, Glass transition temperature of −23 ° C., non-oil-extended product / modified S-SBR2b: solution-polymerized styrene butadiene rubber having a hydroxyl group-containing polyorganosiloxane structure at the end, Nipol NS612 manufactured by Nippon Zeon Co., Ltd., styrene unit content of 16 wt. %, Glass transition temperature of −63 ° C., non-oil-extended product / SBR: styrene butadiene rubber, NS522 manufactured by Zeon Corporation, styrene unit content of 39% by weight, glass transition temperature of −23 ° C., 100 parts by weight of rubber component Oil exhibition and natural rubber containing 37.5 parts by weight of oil: STR-20
Silica 1: Zeosil 1165MP manufactured by Rhodia, nitrogen adsorption specific surface area of 160 m ² / g, CTAB specific surface area of 159 m ² / g
Silica 2: Zeosil Premium 200MP manufactured by Rhodia, a nitrogen adsorption specific surface area of 200 m ² / g, and a CTAB specific surface area of 197 m ² / g
Silica 3: Zeosil 115GR manufactured by Rhodia, nitrogen adsorption specific surface area of 110 m ² / g, CTAB specific surface area of 106 m ² / g
・ Carbon black: HAF grade carbon black, Seast KH made by Tokai Carbon
Silane coupling agent: Sulfur-containing silane coupling agent, Si69 manufactured by Degussa
-Modified terpene resin: YS resin TO125 (softening point 125 ° C.) manufactured by Yasuhara Chemical Co., Ltd.
-Oil: Extract No. 4 S manufactured by Showa Shell Sekiyu KK (DMSO extract 2.6% by weight)

The types of raw materials used in Table 3 are shown below.
・ Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Co., Ltd. ・ Stearic acid: Beads stearic acid YR manufactured by NOF Corporation
Anti-aging agent: Santoflex 6PPD manufactured by Flexis
-Wax: Sannok manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.-Processing aid: SCHILL & SEILACHER Gmbh. & CO. STRUKTOL A50P
・ Sulfur: Fine powder sulfur with Jinhua seal oil manufactured by Tsurumi Chemical Industry Co., Ltd. ・ Vulcanization accelerator 1: Vulcanization accelerator CBS, Noxeller CZ-G manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
・ Vulcanization accelerator 2: Vulcanization accelerator DPG, Noxeller D manufactured by Ouchi Shinsei Chemical Co., Ltd.

  As is apparent from Table 1, the rubber compositions for tire treads of Examples 1 to 4 maintain processability (Mooney viscosity), low rolling resistance (tan δ at 60 ° C.), wet steering stability, and dry steering stability. -It was confirmed that it improved.

  Since the total amount (A) of the modified terpene resin and oil exceeds 30 parts by weight, the rubber composition of Comparative Example 2 is inferior in dry handling stability and wet handling stability. In the rubber composition of Comparative Example 3, the difference between the total amount of silica and carbon black (B) and the total amount of modified terpene resin and oil (A) is less than 75 parts by weight. Inferior. The rubber composition of Comparative Example 4 has a high rolling resistance because the silica ratio with respect to the total amount (B) of silica and carbon black is less than 90% by weight.

  As can be seen from Table 2, the rubber composition of Comparative Example 5 is inferior in dry steering stability and wet steering stability because the content of modified S-SBR1a is less than 60% by weight. The rubber composition of Comparative Example 6 is inferior in dry handling stability and wet handling stability because the styrene content of the modified S-SBR2a and the modified S-SBR2b is less than 30% by weight without adding the modified S-SBR1. . The rubber composition of Comparative Example 7 is inferior in dry steering stability and wet steering stability because the total of the modified S-SBR1a and the modified S-SBR2b is less than 90% by weight.

In the rubber composition of Comparative Example 8, since the nitrogen adsorption specific surface area of silica 2 exceeds 180 m ² / g and the CTAB specific surface area exceeds 170 m ² / g, the dispersibility of silica deteriorates and the processability deteriorates. Since the rubber composition of Comparative Example 9 has a nitrogen adsorption specific surface area of silica 3 of less than 140 m ² / g and a CTAB specific surface area of less than 140 m ² / g, the dry steering stability and the wet steering stability are inferior. The rubber composition of Comparative Example 10 has a high rolling resistance because the amount of silica 1 is less than 90 parts by weight and the silica ratio to the total amount (B) with carbon black is less than 90% by weight. In the rubber composition of Comparative Example 11, since the amount of silica 1 exceeds 120 parts by weight, the rolling resistance increases and the processability deteriorates. The rubber composition of Comparative Example 12 is inferior in wet handling stability because the amount of the modified terpene resin is less than 3.0 parts by weight.

Claims (4)

To 100 parts by weight of a diene rubber containing 60% by weight or more of a terminal-modified solution-polymerized styrene butadiene rubber (modified S-SBR1), 3.0 parts by weight or more of a modified terpene resin, 90 to 120 parts by weight of silica and carbon black A blended rubber composition, wherein the content of the terminally modified solution-polymerized styrene butadiene rubber containing the modified S-SBR1 is 90% by weight or more in 100% by weight of the diene rubber, and the modified S-SBR1 has The functional group is reactive with the silanol group on the silica surface, the styrene unit content is 30 to 45 wt%, the glass transition temperature is -40 ° C to -10 ° C, and the nitrogen adsorption specific surface area of the silica is 140 to 180m ² / g, CTAB specific surface area of 140~170m ² / g, relative to the total amount of the silica and carbon black (B) The ratio of Rica is 90% by weight or more, the total amount (A) of the modified terpene resin and the amount of oil contained in the rubber composition is 30 parts by weight or less, the total amount (B) and the total amount (A) The tire tread rubber composition, wherein the difference is 75 parts by weight or more.   The functional group of the modified S-SBR1 is selected from a hydroxyl group-containing polyorganosiloxane structure, alkoxysilyl group, hydroxyl group, aldehyde group, carboxyl group, amino group, imino group, epoxy group, amide group, thiol group, and ether group. The rubber composition for a tire tread according to claim 1, wherein the rubber composition is at least one.   The rubber composition for a tire tread according to claim 1 or 2, wherein the diene rubber contains the modified S-SBR1 and other terminal-modified solution-polymerized styrene butadiene rubber (modified S-SBR2).   A pneumatic tire using the rubber composition for a tire tread according to claim 1, 2 or 3.