Rubber composition for tires and tires using the same

Abstract

A rubber composition for a tire according to the present invention comprises a diene-based rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound. A blending amount a of the silica is 80-300 parts by mass with respect to 100 parts by mass of the diene-based rubber, and a blending amount b of the sulfur-containing silane coupling agent and the blending amount c of the alkylalkoxysilane compound satisfy the expressions (1) and (2). (1): 0.03 < (b / a) < 0.06, (2): c / b ≥ 1.5

Description

[Technical Field]

[0001] This invention relates to a rubber composition for tires and a tire using the same, and more specifically, to a rubber composition for tires that has excellent scorch resistance without impairing wet grip performance, and a tire using the same. [Background technology]

[0002] Generally, for racing, pneumatic tires are available for both dry and wet surfaces, and the optimal tire is selected according to the weather and road conditions during racing. For racing tires used on wet surfaces, methods such as incorporating a large amount of silica or silica with a high specific surface area are used to improve wet grip performance. However, silica has low affinity with rubber components, and silica particles tend to aggregate well. Therefore, simply adding silica to the rubber components does not allow the silica to disperse properly, resulting in insufficient improvement in wet grip performance. To address these problems, it is common practice to incorporate a silane coupling agent that reacts with silica into a silica-containing rubber composition. However, if a large amount of silane coupling agent is added in conjunction with a large amount of silica or a high specific surface area silica composition, the scorching time becomes shorter, and vulcanization progresses during mixing and extrusion, leading to poor processability and a tendency for so-called burning to occur.

[0003] Examples of conventional technologies aimed at improving the wet grip performance of tires include the following patent documents 1 to 6. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Open Brochure WO2013 / 133432 [Patent Document 2] Japanese Patent Publication No. 2019-104484 [Patent Document 3] Patent No. 6969243 [Patent Document 4] Patent No. 5888361 [Patent Document 5] Patent No. 5644838 [Patent Document 6] Patent No. 7397272 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional technologies do not disclose or suggest any technical concept for simultaneously improving wet grip performance and scorch resistance by appropriately combining sulfur-containing silane coupling agents and alkylalkoxysilane compounds. For example, Patent Document 6 discloses a cap tread rubber compounded with silica, terpene resin, silane coupling agent, and alkyltriethoxysilane to a modified diene rubber, but it does not disclose or suggest the ratio of silica, sulfur-containing silane coupling agent, and alkylalkoxysilane compound of the present invention described below, nor does it describe anything about improving scorch resistance. The object of the present invention is to provide a tire rubber composition that has excellent scorch resistance without impairing wet grip performance, and a tire using the same. [Means for solving the problem]

[0006] As a result of diligent research, the inventors have discovered that the above problems can be solved by specifying the amount of silica and the type of alkylalkoxysilane compound in a tire rubber composition containing diene rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound, and further specifying the blending ratio of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound, thereby completing the present invention.

[0007] In other words, the present invention provides a tire rubber composition containing a diene rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound, wherein the amount of silica is 80 to 300 parts by mass per 100 parts by mass of the diene rubber, the alkylalkoxysilane compound is alkyldiethoxysilane or alkyltriethoxysilane, and the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound satisfy the following formulas (1) and (2). 0.03 < (b / a) < 0.06 (1) c / b ≥ 1.5 (2) In formulas (1) and (2) above, a is the amount of silica blended per 100 parts by mass of the diene rubber (parts by mass), b is the amount of the sulfur-containing silane coupling agent blended per 100 parts by mass of the diene rubber (parts by mass), and c is the amount of the alkylalkoxysilane compound blended per 100 parts by mass of the diene rubber (parts by mass). The present invention also provides a tire using the aforementioned tire rubber composition. [Effects of the Invention]

[0008] According to the present invention, a tire rubber composition containing a diene rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound is provided, wherein the amount of silica is 80 to 300 parts by mass per 100 parts by mass of the diene rubber, the alkylalkoxysilane compound is alkyldiethoxysilane or alkyltriethoxysilane, and the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound satisfy formulas (1) and (2). Therefore, a tire rubber composition and a tire using the same can be provided that have excellent scorch resistance without impairing wet grip performance.

[0009] As mentioned above, methods such as incorporating large amounts of silica or silica with a high specific surface area have been employed to improve the wet grip performance of tires. However, silica has low affinity for rubber components, requiring the incorporation of large amounts of silane coupling agents. This method has the problem of shortening the scorch time and worsening processability (deterioration of scorch resistance). This problem is particularly pronounced when using sulfur-containing silane coupling agents that have excellent silica dispersibility but are highly reactive. Therefore, in the present invention, by using a specific alkylalkoxysilane compound that is effective in dispersing silica but does not contain sulfur, and by specifying the ratio of sulfur-containing silane coupling agent to alkylalkoxysilane compound, the high reactivity of the sulfur-containing silane coupling agent is suppressed while maintaining the silica dispersion effect inherent in the sulfur-containing silane coupling agent, thereby improving scorch resistance and maintaining wet grip performance. [Modes for carrying out the invention]

[0010] The present invention will be described in more detail below.

[0011] (Diene-based rubber) The diene rubber used in the tire rubber composition of the present invention (hereinafter sometimes simply referred to as the rubber composition) preferably contains styrene-butadiene copolymer rubber (SBR) as an essential component. When the total diene rubber used in the present invention is 100 parts by mass, the amount of SBR can be determined by appropriately considering various conditions such as temperature and weather in the case of competitive use, but it can be, for example, 70 parts by mass or more, preferably 85 parts by mass or more, and more preferably 100 parts by mass. In addition to SBR, the present invention can use any diene rubber that can be blended into a normal rubber composition, such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), and ethylene-propylene-diene polymer (EPDM). These may be used alone or in combination of two or more. The SBR used in the present invention is not particularly limited in terms of its molecular weight and microstructure, but it is also a preferred form that is end-modified with amine, amide, silyl, alkoxysilyl, carboxyl, hydroxyl groups, etc. In addition, from the perspective of improving the effects of the present invention, the SBR used in the present invention preferably has a styrene content of 20 to 45% by mass and / or a glass transition temperature (Tg) of -60 to -10 °C (where the Tg is a value measured excluding the oil used for oil extension when the SBR is oil-extended). The glass transition temperature (Tg) referred to in the present invention is defined as the temperature at the midpoint of the transition region, measured by differential scanning calorimetry (DSC) under the condition of a heating rate of 20 °C / min to obtain a thermogram. is preferred.

[0012] (Silica) The silica used in the present invention can employ so-called high specific surface area silica. Specifically, the silica used in the present invention preferably has a nitrogen adsorption specific surface area N2SA of 100 to 300 m 2 / g, and more preferably 130 to 270 m 2 / g. The N2SA shall be measured in accordance with JIS K6217-2. In the present invention, silica made from biomass materials such as rice husks may also be used.

[0013] (Sulfur-containing silane coupling agent) The sulfur-containing silane coupling agent used in the present invention may be any one that can be used in a rubber composition containing silica. For example, bis-(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, etc. can be exemplified. Also, for example, the sulfur-containing silane coupling agent represented by the following formula (2) disclosed in International Publication WO2014 / 002750 pamphlet can also be used. (A)a (B) b (C) c (D) d (R1) e SiO (4-2a-b-c-d-e) / 2 (2) (In formula (2), A represents a divalent organic group containing a sulfide group, B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms, C represents a hydrolyzable group, D represents an organic group containing a mercapto group, R1 represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, and the relationships 0 ≦ a < 1, 0 < b < 1, 0 < c < 3, 0 < d < 1, 0 ≦ e < 2, and 0 < 2a + b + c + d + e < are satisfied.) In the present invention, even when a silane coupling agent having a highly reactive mercapto group is used, improvement in scorch resistance is possible.

[0014] (Alkylalkoxysilane compound) The alkylalkoxysilane compound used in the present invention is an alkyldiethoxysilane or an alkyltriethoxysilane. The alkyldiethoxysilane can be represented by the following formula (3), and the alkyltriethoxysilane can be represented by the following formula (4).

[0015] [Chemical formula]

[0016] In formulas (3) and (4), R1, R2, and R3 each independently represent an alkyl group having 1 to 20 carbon atoms, and Et represents an ethyl group. Here, among the alkyl groups having 1 to 20 carbon atoms for R1 and R2, a methyl group is particularly preferable. Among the alkyl groups having 1 to 20 carbon atoms for R3, an alkyl group having 7 to 20 carbon atoms is particularly preferable. Specifically, examples include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, etc. Among these, from the perspective of compatibility with a diene-based rubber, an alkyl group having 8 to 10 carbon atoms is more preferable, and an octyl group and a nonyl group are particularly preferable.

[0017] (Aluminum hydroxide) In the present invention, from the viewpoint of improving the effect, aluminum hydroxide can be blended. The conditions such as the particle size distribution of aluminum hydroxide are not particularly limited, and it can be appropriately selected from known ones. For example, BF013 manufactured by Nippon Light Metal Co., Ltd. can be mentioned as a commercially available product.

[0018] (Carbon black) In the present invention, carbon black can be blended. The above carbon black is not particularly limited, and for example, various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF can be used. It is preferable that the nitrogen adsorption specific surface area N2SA of carbon black is 100 to 250 m 2 / g.

[0019] (Adhesion-imparting resin) In order to further improve the effect of the rubber composition of the present invention, an adhesion-imparting resin can be blended. The tackifying resin used in the present invention is not particularly limited, but specific examples include phenolic resins (e.g., phenolic resins, phenol-acetylene resins, phenol-formaldehyde resins), coumarone resins (e.g., coumarone resins, coumarone-indene resins, coumarone-indene-styrene resins), terpene resins (e.g., terpene resins, modified terpene resins (aromatic modified terpene resins, etc.), terpene phenolic resins), styrene resins, acrylic resins, rosin resins (e.g., rosin, rosin esters, hydrogenated rosin derivatives), hydrogenated terpene resins), petroleum resins (e.g., C5 petroleum resins such as dicyclopentazine resin, C9 petroleum resins, alicyclic petroleum resins, C5 / C9 copolymer petroleum resins), xylene resins (e.g., xylene resins, xylene-acetylene resins, xylene-formaldehyde resins), α-pinene resins, aliphatic saturated hydrocarbon resins, and the like. In particular, for reasons that the effects of the present invention are superior, it is preferable to use one or more selected from C9 petroleum resin, phenolic resin, coumarone indene resin, terpene resin, modified terpene resin, styrene resin, acrylic resin, rosin resin, and dicyclopentadiene resin. Examples of modified terpene resins include aromatic modified terpene resins. For example, aromatic modified terpene resins obtained by polymerizing terpene resins such as α-pinene, β-pinene, dipentene, and limonene with aromatic compounds such as styrene, α-methylstyrene, vinyltoluene, and indene are effectively used. Commercially available aromatic modified terpene resins can be used. For example, YS Resin TO-125 (terpene styrene resin, Mw=2000, softening point 120~130℃) manufactured by Yasuhara Chemical Co., Ltd. is one such example.

[0020] (Ratio of rubber composition) In the rubber composition of the present invention, the amount of silica is 80 to 300 parts by mass, preferably 100 to 250 parts by mass, per 100 parts by mass of diene rubber. If the amount of silica is less than 80 parts by mass, the tanδ0℃ decreases, and if it exceeds 300 parts by mass, the scorch resistance deteriorates. In the rubber composition of the present invention, the amount of sulfur-containing silane coupling is preferably 3.5 to 5.5% by mass, and more preferably 4 to 5% by mass, relative to the amount of silica. In the rubber composition of the present invention, the amount of alkylalkoxysilane compound blended is preferably 10 to 20 parts by mass, and more preferably 12 to 18 parts by mass, per 100 parts by mass of diene rubber.

[0021] In the rubber composition of the present invention, in order to achieve the effects of the present invention, the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound must satisfy the following formulas (1) and (2), and it is more preferable that they satisfy the following formulas (11) and (21).

[0022] 0.03 < (b / a) < 0.06 (1) c / b ≥ 1.5 (2)

[0023] 0.032 < (b / a) < 0.058 (11) 1.6 <c / b<5.0 (21)

[0024] In formulas (1) and (2) above, a is the amount of silica blended per 100 parts by mass of the diene rubber (parts by mass), b is the amount of the sulfur-containing silane coupling agent blended per 100 parts by mass of the diene rubber (parts by mass), and c is the amount of the alkylalkoxysilane compound blended per 100 parts by mass of the diene rubber (parts by mass).

[0025] Furthermore, in one embodiment of the present invention, when aluminum hydroxide is used, the amount of aluminum hydroxide added is preferably 15 parts by mass or more, and more preferably 20 to 80 parts by mass, per 100 parts by mass of the diene rubber. When carbon black is used, the amount added is preferably 3 to 50 parts by mass per 100 parts by mass of the diene-based rubber. When using a tackifying resin, the amount blended is preferably 10 to 100 parts by mass per 100 parts by mass of the diene rubber.

[0026] (Other ingredients) In addition to the components mentioned above, the rubber composition of the present invention may contain various additives commonly used in rubber compositions, such as vulcanizing or crosslinking agents; vulcanizing or crosslinking accelerators; various fillers such as clay, talc, and calcium carbonate; antioxidants; plasticizers; resins; and curing agents. These additives can be mixed in a conventional manner to form a composition which can then be used for vulcanization or crosslinking. The amounts of these additives can also be conventional amounts, as long as they do not contradict the purpose of the present invention. The method for producing the rubber composition of the present invention is not particularly limited. Specific examples include, for instance, a method of kneading the above-mentioned components using known methods and equipment (e.g., Banbury mixer, kneader, rolls, etc.). If the composition of the present invention contains a vulcanizing agent (e.g., sulfur) and a vulcanization accelerator, it is preferable to first mix the components other than the vulcanizing agent and vulcanization accelerator at a high temperature (preferably 100-155°C), cool them, and then mix in the vulcanizing agent and vulcanization accelerator, for reasons that the effects of the present invention are superior in the resulting composition. The composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0027] The rubber composition of the present invention can be suitably used for tire treads, particularly cap treads, and preferably for racing tire treads, especially cap treads. Furthermore, the tire of the present invention is preferably a pneumatic tire and can be filled with air, an inert gas such as nitrogen, and other gases. [Examples]

[0028] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0029] Standard Example 1, Examples 1-6, Comparative Examples 1-6 In the formulations (parts by mass) shown in Table 1, the components excluding the vulcanization system (vulcanization accelerator, sulfur) were kneaded in a 1.7-liter sealed Banbury mixer for 5 minutes, then released from the mixer and cooled to room temperature. Subsequently, the composition was put back into the Banbury mixer, the vulcanization system was added and kneaded to obtain a rubber composition. Next, the obtained rubber composition was press-vulcanized in a predetermined mold at 150°C for 30 minutes to prepare vulcanized rubber test specimens. The physical properties of the obtained vulcanized rubber test specimens were measured using the test methods described below.

[0030] Scorch time: Tested at 125°C according to JIS K6300. Results are shown as an index, with the value of Standard Example 1 set to 100. A higher index indicates better scorch performance. Wet grip performance: In accordance with JIS K6394:2007, tanδ(0°C) was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of tensile deformation strain of 10±2%, frequency of 20Hz, and temperature of 0°C. The results are expressed as an index with standard example 1 set to 100. A higher index indicates better wet grip performance.

[0031] The results are shown in Table 1.

[0032] Standard Example 2, Examples 7-12, Comparative Examples 7-12 The above-mentioned "Standard Example 1, Examples 1-6, and Comparative Examples 1-6" were repeated, except that the proportions of each ingredient were changed as shown in Table 2. The results are shown in Table 2. Note that the results for Examples 7-12 and Comparative Examples 7-12 are the values ​​relative to Standard Example 2 in Table 2.

[0033] Standard Example 3, Examples 13-18, Comparative Examples 13-18 The above-mentioned "Standard Example 1, Examples 1-6, and Comparative Examples 1-6" were repeated, except that the proportions of each ingredient were changed as shown in Table 3. The results are shown in Table 3. Note that the results for Examples 13-18 and Comparative Examples 13-18 are the values ​​relative to Standard Example 3 in Table 3.

[0034] [Table 1]

[0035] [Table 2]

[0036] [Table 3]

[0037] *1: SBR (Nipol NS522 manufactured by ZS Elastomer Co., Ltd., styrene content = 39% by mass, oil-treated product with 37.5 parts by mass of oil component added to 100 parts by mass of SBR, Tg = -25℃ of SBR excluding the oil component) *2: Silica (Evonik Ultrasil 7000GR, nitrogen adsorption specific surface area N2SA = 172 m²) 2 / g) *3: Carbon black (Seas 9 manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area N2SA = 142m²) 2 / g) *4: Aluminum hydroxide (BF013 manufactured by Nippon Light Metal Co., Ltd.) *5: Resin 1 (Neopolymer 140S manufactured by ENEOS Corporation) *6: Silane coupling agent 1 (Si69 manufactured by Evonik) *7: Silane coupling agent 2 (Si363 manufactured by Evonik. It has a mercapto group at the terminal end.) *8: Alkyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd., octyltriethoxysilane) *9: Alkyldiethoxysilane (KBE-22, manufactured by Shin-Etsu Chemical Co., Ltd., dimethyldiethoxysilane) *10: Oil (Showa Shell Sekiyu Extract No. 4 S) *11: Stearic acid (Bead Stearic Acid YR, manufactured by NOF Corporation) *12: Zinc oxide (3 types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd.) *13: Anti-aging agent (Flexis 6PPD) *14: Vulcanization accelerator 1 (Sunceller DG manufactured by Sanshin Chemical Industry Co., Ltd.) *15: Vulcanization accelerator 2 (Noxellar CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) *16: Sulfur (Finely powdered sulfur containing Kinka oil, manufactured by Tsurumi Chemical Industries Co., Ltd.) *17: Terminal-modified SBR (Asahi Kasei Corporation product name TUFDENE E581, styrene content = 36% by mass, oil-extracted product with 37.5 parts by mass of oil component added to 100 parts by mass of SBR, terminals modified with hydroxyl groups. Tg = -27℃ of SBR excluding the oil component.) *18: Resin 2 (YS Resin TO125 manufactured by Yasuhara Chemical Co., Ltd.)

[0038] From the results in Tables 1-3, it can be seen that the rubber compositions of each example contain a diene rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound, with the amount of silica being 80 to 300 parts by mass per 100 parts by mass of the diene rubber, the alkylalkoxysilane compound being alkyldiethoxysilane or alkyltriethoxysilane, and the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound satisfying formulas (1) and (2). Therefore, compared to standard example 1, 2, or 3, it can be seen that they have superior scorch resistance without impairing wet grip performance. In contrast, in Comparative Example 1, (b / a) and (2) are 0.10 and c / b is 0.5, so the scorch time worsened. In Comparative Example 2, the scorch time worsened because (b / a) was 0.06 and c / b was 0.8 in equations (1) and (2) above. In Comparative Example 3, the scorch time worsened because (b / a) was 0.10 and c / b was 1.0 in equations (1) and (2) above. In Comparative Example 4, since c / b is 1.3 in equations (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 5, since (b / a) is 0.02 in equations (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 6, the scorch time worsened because (b / a) was 0.10 in equations (1) and (2) above. In Comparative Example 7, in equations (1) and (2) above, (b / a) and are 0.10, and c / b is 0.3, so the scorch time worsened. In Comparative Example 8, the scorch time worsened because (b / a) was 0.06 and c / b was 0.4 in equations (1) and (2) above. In Comparative Example 9, the scorch time worsened because (b / a) was 0.10 and c / b was 0.5 in equations (1) and (2) above. In Comparative Example 10, since c / b is 0.6 in equations (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 11, since (b / a) is 0.02 in formulas (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 12, the scorch time worsened because (b / a) was 0.10 in equations (1) and (2) above. In Comparative Example 13, the scorch time worsened because (b / a) was 0.10 and c / b was 0.3 in equations (1) and (2) above. In Comparative Example 14, the scorch time worsened because (b / a) was 0.06 and c / b was 0.3 in equations (1) and (2) above. In Comparative Example 15, the scorch time worsened because (b / a) was 0.10 and c / b was 0.7 in equations (1) and (2) above. In Comparative Example 16, since c / b is 0.8 in equations (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 17, since (b / a) is 0.02 in equations (1) and (2) above, the wet grip performance deteriorated. In Comparative Example 18, the scorch time worsened because (b / a) was 0.10 in equations (1) and (2) above.

[0039] The present invention encompasses the following embodiments. Embodiment 1: A tire rubber composition containing diene rubber, silica, a sulfur-containing silane coupling agent, and an alkylalkoxysilane compound, The amount of silica added is 80 to 300 parts by mass per 100 parts by mass of the diene rubber. The alkylalkoxysilane compound is alkyldiethoxysilane or alkyltriethoxysilane. A rubber composition for tires characterized in that the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound satisfy the following formulas (1) and (2). 0.03 < (b / a) < 0.06 (1) c / b ≥ 1.5 (2) In formulas (1) and (2) above, a is the amount of silica blended per 100 parts by mass of the diene rubber (parts by mass), b is the amount of the sulfur-containing silane coupling agent blended per 100 parts by mass of the diene rubber (parts by mass), and c is the amount of the alkylalkoxysilane compound blended per 100 parts by mass of the diene rubber (parts by mass). Embodiment 2: The tire rubber composition according to Embodiment 1, characterized in that the sulfur-containing silane coupling agent is a sulfur-containing silane coupling agent having a mercapto group. Embodiment 3: The tire rubber composition according to Embodiment 1 or 2, characterized in that 15 parts by mass or more of aluminum hydroxide is further added to 100 parts by mass of the diene rubber. Embodiment 4: The tire rubber composition according to any one of Embodiments 1 to 3, characterized in that styrene-butadiene copolymer rubber accounts for 70 parts by mass or more of 100 parts by mass of the diene rubber. Embodiment 5: The tire rubber composition according to Embodiment 4, characterized in that the styrene content of the styrene-butadiene copolymer rubber is 20 to 45% by mass, and / or the glass transition temperature (Tg) is -60 to -10°C. Embodiment 6: The nitrogen adsorption specific surface area (N2SA) of the silica is 100-300 m².2 A tire rubber composition according to any one of Embodiments 1 to 5, characterized in that it is / g. Embodiment 7: The tire rubber composition according to any one of Embodiments 1 to 6, characterized in that the alkyl group in the alkyldiethoxysilane is a methyl group. Embodiment 8: The tire rubber composition according to any one of Embodiments 1 to 6, characterized in that the alkyl group in the alkyltriethoxysilane is an alkyl group having 7 to 20 carbon atoms. Embodiment 9: A tire using the tire rubber composition described in any of Embodiments 1 to 8.

Claims

1. A tire rubber composition comprising a diene rubber, silica, a sulfur-containing silane coupling agent, an alkylalkoxysilane compound, and a tackifying resin, The amount of silica added is 80 to 300 parts by mass per 100 parts by mass of the diene rubber. The alkylalkoxysilane compound is alkyldiethoxysilane or alkyltriethoxysilane. The amount of the tackifying resin blended is 10 to 100 parts by mass per 100 parts by mass of the diene rubber. The tackifying resin is one or more selected from C9 petroleum resins, phenolic resins, coumarone indene resins, terpene resins, modified terpene resins, styrene resins, acrylic resins, rosin resins, and dicyclopentadiene resins. A rubber composition for tires characterized in that the amounts of the sulfur-containing silane coupling agent and the alkylalkoxysilane compound satisfy the following formulas (1) and (2). 0.03<(b / a)<0.06 (1) c / b≧1.5 (2) In formulas (1) and (2) above, a is the amount (parts by mass) of silica blended with 100 parts by mass of the diene rubber, b is the amount (parts by mass) of the sulfur-containing silane coupling agent blended with 100 parts by mass of the diene rubber, and c is the amount (parts by mass) of the alkylalkoxysilane compound blended with 100 parts by mass of the diene rubber.

2. The tire rubber composition according to claim 1, characterized in that the sulfur-containing silane coupling agent is a sulfur-containing silane coupling agent having a mercapto group.

3. The tire rubber composition according to claim 1, further comprising 15 parts by mass or more of aluminum hydroxide with respect to 100 parts by mass of the diene rubber.

4. The tire rubber composition according to claim 1, characterized in that styrene-butadiene copolymer rubber accounts for 70 parts by mass or more of 100 parts by mass of the diene rubber.

5. The tire rubber composition according to claim 4, characterized in that the styrene content of the styrene-butadiene copolymer rubber is 20 to 45% by mass, and / or the glass transition temperature (Tg) is -60 to -10°C.

6. The nitrogen adsorption specific surface area N of the silica ２ SA is 100-300m ２ The tire rubber composition according to claim 1, characterized in that it is / g.

7. The tire rubber composition according to claim 1, characterized in that the alkyl group in the alkyldiethoxysilane is a methyl group.

8. The tire rubber composition according to claim 1, characterized in that the alkyl group in the alkyltriethoxysilane is an alkyl group having 7 to 20 carbon atoms.

9. A tire using the rubber composition for tires described in claim 1.

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