Rubber composition for tires

Abstract

The present invention provides a rubber composition for tires with which both wet gripping performance and wear resistance are attained. The present invention provides a mixture obtained by blending 0.5 to 50 parts by mass of a rosin resin with 100 parts by mass of a diene rubber, the diene rubber and the rosin resin being blended at a mass ratio of 1:1, wherein the mixture is characterized in that the difference Tga–Tgm is 5–50°C, where Tga is a theoretical value Tga for the glass transition temperature of the mixture calculated from the glass transition temperatures of the diene rubber and the rosin resin, and Tgm is the measured value of the glass transition temperature of the mixture.

Description

[Technical field]

[0001] The present invention relates to a rubber composition for tires that combines wet grip performance and abrasion resistance. [Background technology]

[0002] Wet grip performance and abrasion resistance are important performances required for tires. In order to improve the wet grip performance and abrasion resistance, it has been known to blend a thermoplastic resin such as a petroleum resin into a rubber composition for tires.

[0003] For example, Patent Document 1 proposes improving wet grip properties and abrasion resistance by blending an aromatic modified terpene resin into a rubber composition for tires. Aromatic modified terpene resins are made from materials derived from natural ingredients and are environmentally friendly, but the supply of the raw material limonene tends to be unstable, which can be an obstacle when trying to increase the amount of environmentally friendly raw materials used. Therefore, there is a demand for the development of a rubber composition for tires that can achieve both wet grip properties and abrasion resistance by using raw materials with a higher supply stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2013-166864 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a rubber composition for a tire which has both wet grip properties and abrasion resistance. [Means for solving the problem]

[0006] The rubber composition for tires of the present invention that achieves the above-mentioned object comprises 100 parts by mass of diene rubber and 0.5 to 50 parts by mass of rosin-based resin, and is characterized in that in a mixture in which the diene rubber and the rosin-based resin are blended in a mass ratio of 1:1, the difference Tga-Tgm between the theoretical value Tga of the glass transition temperature of the mixture calculated from the glass transition temperatures of the diene rubber and the rosin-based resin and the measured value Tgm of the glass transition temperature of the mixture is 5 to 50°C. Effect of the Invention

[0007] According to the rubber composition for tires of the present invention, by selecting the diene rubber and the rosin resin so that a mixture of a diene rubber and a rosin resin in a mass ratio of 1:1 satisfies a difference Tga-Tgm between the theoretical glass transition temperature Tga and the measured glass transition temperature Tgm of the mixture of 5 to 50°C, it is possible to improve wet grip performance and abrasion resistance to levels higher than those of conventional products.

[0008] The softening point of the rosin-based resin is preferably 80 to 125°C, and the acid value of the rosin-based resin is preferably 15 mgKOH / g or less. Furthermore, the rosin-based resin preferably has aliphatic units derived from aliphatic hydrocarbons and, optionally, aromatic units derived from aromatic hydrocarbons, and the mass ratio of the aliphatic units to the aromatic units (aliphatic units / aromatic units) is preferably 90 / 10 to 100 / 0. The ratio Tg / Mz of the glass transition temperature Tg [°C] to the Z-average molecular weight Mz [-] of the rosin-based resin is preferably 0.02 or more, and the rosin-based resin is preferably a rosin ester resin.

[0009] In the rubber composition for tires for studless tires or stud tires, the diene rubber may contain natural rubber and butadiene rubber, the diene rubber may have an average glass transition temperature of -100°C to -80°C, and 10 to 90 parts by mass of silica may be blended with 100 parts by mass of the diene rubber. The rubber composition may contain 40% or more by mass of the butadiene rubber in 100% by mass of the diene rubber, and may further contain 45 parts by mass or more of a plasticizer relative to 100 parts by mass of the diene rubber.

[0010] In the rubber composition for winter tires, the diene rubber may include a styrene-butadiene rubber and a butadiene rubber, the diene rubber may have an average glass transition temperature of -100°C to -50°C, and 90 to 180 parts by mass of silica may be blended with 100 parts by mass of the diene rubber. Furthermore, the styrene-butadiene rubber having a glass transition temperature of -50°C or higher may account for 60% by mass or more of the 100% by mass of the diene rubber.

[0011] In the rubber composition for all-season tires, the diene rubber may contain styrene-butadiene rubber, the diene rubber may have an average glass transition temperature of -80°C to -40°C, and 10 to 90 parts by mass of silica may be blended with 100 parts by mass of the diene rubber. Furthermore, the rubber composition may contain 50% or more by mass of emulsion-polymerized styrene-butadiene rubber in 100% by mass of the diene rubber.

[0012] In the rubber composition for high performance tires, the diene rubber preferably contains styrene-butadiene rubber, the diene rubber preferably has an average glass transition temperature of -50°C to -20°C, and 90 to 180 parts by mass of silica are blended with 100 parts by mass of the diene rubber. Furthermore, the styrene-butadiene rubber may be contained in an amount of 30% by mass or more in 100% by mass of the diene rubber.

[0013] In the rubber composition for tires for low fuel consumption tires, the diene rubber preferably contains styrene-butadiene rubber, the diene rubber preferably has an average glass transition temperature of -50°C to -20°C, and 10 to 90 parts by mass of silica are blended with 100 parts by mass of the diene rubber. Furthermore, the styrene-butadiene rubber having a glass transition temperature of -50°C or higher is preferably contained in an amount of 70% by mass or more relative to 100% by mass of the diene rubber.

[0014] In the rubber composition for tires, the diene rubber may contain at least one modified styrene-butadiene rubber selected from the following modified SBR1 and modified SBR2. Denatured SBR1; Modified styrene-butadiene rubber 1 is produced by a production method including the following steps A, B, and C in this order, the modified styrene-butadiene rubber having an aromatic vinyl unit content of 38 to 48 mass%, a vinyl bond content of 20 to 35 mass%, and a weight average molecular weight of 500,000 to 800,000. Step A: A step of polymerizing a monomer mixture containing isoprene and aromatic vinyl to form a polymer block A having an active end, the polymer block A having an isoprene unit content of 80 to 95 mass%, an aromatic vinyl unit content of 5 to 20 mass%, and a weight average molecular weight of 500 to 15,000. Step B: A step of mixing the polymer block A with a monomer mixture containing 1,3-butadiene and an aromatic vinyl to continue the polymerization reaction, thereby forming a polymer block B having an active end in a continuous state with the polymer block A, thereby obtaining a conjugated diene-based polymer chain having an active end, which includes the polymer block A and the polymer block B. Step C: A step of reacting the active terminal of the conjugated diene polymer chain with a polyorganosiloxane represented by the following formula (1): [ka] (In formula (1), R 1 ~R 8 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. X 1 and X 4 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 2 is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, 2 may be the same or different. X 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3When there are a plurality of, they may be the same or different. m is an integer of 3 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200.) Modified SBR2; A modified styrene-butadiene rubber 2 produced by a production method including: a first step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; a second step of adding and reacting the polyorganosiloxane represented by the formula (1) to the conjugated diene polymer chain having an active end in a ratio of 1 mol or more calculated as the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane per 1 mol of the polymerization initiator used in the first step; and a third step of reacting the conjugated diene polymer chain reacted with the polyorganosiloxane obtained in the second step with a compound represented by the following formula (2). [ka] (In formula (2), R 9 is a hydrocarbyl group, A 1 is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane, and A 2 is a monovalent group containing a nitrogen atom (excluding groups containing an oxygen atom), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

[0015] The above-mentioned rubber composition for a tire can be suitably used to form a tread portion of a tire. A tire having a tread portion formed of the rubber composition for a tire of the present invention can achieve both wet grip performance and abrasion resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The rubber composition for tires contains diene rubber that is usually used in tires. Examples of diene rubber include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, styrene isoprene rubber, isoprene butadiene rubber, ethylene-propylene-diene copolymer rubber, chloroprene rubber, and acrylonitrile butadiene rubber. These diene rubbers may be modified with one or more functional groups. The type of functional group is not particularly limited, but examples thereof include epoxy groups, carboxy groups, amino groups, hydroxy groups, alkoxy groups, silyl groups, alkoxysilyl groups, amide groups, oxysilyl groups, silanol groups, isocyanate groups, isothiocyanate groups, carbonyl groups, and aldehyde groups.

[0017] The natural rubber, butadiene rubber, and styrene-butadiene rubber are not particularly limited as long as they are normally used in rubber compositions for tires. By compounding natural rubber, the abrasion resistance of the tire can be ensured. Furthermore, by compounding butadiene rubber, the performance on ice and snow of the tire can be ensured. Furthermore, by compounding styrene-butadiene rubber, the wet grip performance of the tire can be ensured.

[0018] The rubber composition for tires needs to combine the diene rubber and the rosin resin so as to satisfy the following relationship. That is, in a mixture in which the diene rubber and the rosin resin are blended at a mass ratio of 1:1, the difference Tga-Tgm between the theoretical value Tga of the glass transition temperature of the mixture calculated from the glass transition temperatures of the diene rubber and the rosin resin and the measured value Tgm of the glass transition temperature of the mixture is set to 5 to 50°C. By setting the difference Tga-Tgm to 5°C or more, the wet performance is improved. Also, by setting the difference Tga-Tgm to 50°C or less, the delay in the vulcanization rate is suppressed and the wet performance is also improved. The difference Tga-Tgm is preferably 8 to 47°C, more preferably 10 to 45°C. In this specification, the glass transition temperatures of the diene rubber and rosin resin, and the glass transition temperature Tgm of the mixture are measured as the midpoint temperature of the transition region by measuring a thermogram at a heating rate of 20° C. / min by differential scanning calorimetry (DSC). The theoretical glass transition temperature Tga of the mixture can be calculated as a weighted average value from the glass transition temperatures and mass ratios of the diene rubber and rosin resin.

[0019] The rubber composition for tires can achieve both wet grip properties and abrasion resistance by blending 0.5 to 50 parts by mass of rosin-based resin with 100 parts by mass of diene-based rubber. If the amount of rosin-based resin is less than 0.5 parts by mass, the effect of achieving both wet grip properties and abrasion resistance cannot be sufficiently obtained. If the amount of rosin-based resin is more than 50 parts by mass, the vulcanization speed is slowed down and processability is reduced. The amount of rosin-based resin blended is preferably 3 to 47 parts by mass, more preferably 5 to 45 parts by mass.

[0020] The rosin-based resin is a material derived from natural components, and the mass percentage of the natural components is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The mass percentage of the natural components is preferably 100% or less, more preferably 98% or less, and even more preferably 96% or less. By using a rosin-based resin with such a high mass percentage of natural components, it is possible to produce a tire material that is friendly to the global environment.

[0021] The softening point of the rosin-based resin is preferably 80 to 125°C, more preferably 85 to 120°C, and even more preferably 90 to 115°C. By setting the softening point at 80°C or higher, deterioration of processability such as roll adhesion can be prevented, which is preferable. In addition, by setting the softening point at 125°C or lower, deterioration due to heat can be prevented, which is preferable. In this specification, the softening point of the rosin-based resin is measured based on JIS K6220-1 (ring and ball method).

[0022] The acid value of the rosin resin is preferably 15 mgKOH / g or less, more preferably 1 to 14 mgKOH / g, and further preferably 2 to 13 mgKOH / g. By making the acid value of the rosin resin 15 mgKOH / g or less, it is possible to prevent a delay in the vulcanization rate, which is preferable. In this specification, the acid value of the rosin resin is measured in accordance with JIS K5902.

[0023] The rosin-based resin has aliphatic units derived from aliphatic hydrocarbons and, optionally, aromatic units derived from aromatic hydrocarbons, and the mass ratio of the aliphatic units and aromatic units (aliphatic units / aromatic units) is preferably 90 / 10 to 100 / 0, more preferably 92 / 8 to 98 / 2, and even more preferably 93 / 7 to 97 / 3. By setting the mass ratio (aliphatic units / aromatic units) to 90 / 10 or more and 100 / 0 or less, wet performance is improved and a delay in the vulcanization rate is suppressed, which is preferable. In this specification, the mass ratio (aliphatic units / aromatic units) of the rosin-based resin is 1 It can be determined from the peak area ratio of H-NMR.

[0024] The ratio Tg / Mz of the glass transition temperature Tg [°C] to the Z-average molecular weight Mz [-] of the rosin resin is preferably 0.02 or more, more preferably 0.025 to 0.10, and even more preferably 0.030 to 0.070. By making the ratio Tg / Mz 0.02 or more, it is preferable that the abrasion resistance is improved. The glass transition temperature Tg [°C] of the rosin resin can be measured by the above-mentioned method. In addition, in this specification, the Z-average molecular weight Mz of the rosin resin can be measured under the following conditions as the molecular weight in terms of polystyrene by gel permeation chromatography (GPC). Measurement equipment: Waters GPC (ALC / GPC 150C) Column: Showa Denko AD806M / S (3 columns) Mobile phase type: Orthodichlorobenzene (ODCB) Mobile phase flow rate: 1.0 ml / min Measurement temperature: 140℃ Detector type: FOXBORO MIRAN 1A IR detector (measurement wavelength: 3.42 μm)

[0025] Rosin is a natural resin, such as gum rosin, wood rosin, or tall oil rosin, which is obtained by processing pine resin and contains as its main components resin acids, such as abietic acid, levopimaric acid, neoabietic acid, palustric acid, isopimaric acid, sandaracopimaric acid, pimaric acid, dehydroabietic acid, dihydroabietic acid, and dextropimaric acid.

[0026] The rosin-based resin includes rosin and ester derivatives of rosin (rosin ester resin), but does not include modified products of rosin. The rosin-based resin is preferably a rosin ester resin. Examples of the rosin ester resin include glycerin ester, pentaerythritol ester, dipentaerythritol ester, methyl ester, ethylene glycol ester, diethylene glycol ester, and triethylene glycol ester. The rosin ester resin is produced, for example, by heating rosin and a polyol such as glycerin or pentaerythritol to 200 to 300°C under an inert gas atmosphere and removing the generated water from the system.

[0027] In this specification, examples of modified resins excluded from the rosin-based resin include rosin-modified phenolic resins and maleic acid-modified rosin resins.

[0028] The rubber composition for tires may contain 5 to 300 parts by mass, more preferably 30 to 150 parts by mass, of an inorganic filler per 100 parts by mass of diene rubber. By compounding the inorganic filler, tire durability such as abrasion resistance and steering stability can be ensured. Examples of the inorganic filler include carbon black, silica, calcium carbonate, magnesium carbonate, talc, clay, mica, alumina, aluminum hydroxide, titanium oxide, and calcium sulfate. The inorganic fillers may be used alone or in combination of two or more kinds.

[0029] The carbon black is not particularly limited as long as it is one that is normally used in rubber compositions for tires. The nitrogen adsorption specific surface area is preferably 50 to 160 m 2 / g, more preferably 80 to 150m 2 / g, more preferably 100 to 130 m 2 / g. The nitrogen adsorption specific surface area is preferably 50m 2 / g or more ensures tire durability. 2 By making the specific surface area of ​​carbon black equal to or less than 1 / g, heat buildup can be reduced and low rolling resistance can be ensured. The nitrogen adsorption specific surface area of ​​carbon black can be determined in accordance with JIS K6217-2.

[0030] Carbon black can be blended in an amount of preferably 5 to 100 parts by mass, more preferably 5 to 80 parts by mass, per 100 parts by mass of diene rubber. By blending 5 parts by mass or more of carbon black, tire durability can be ensured. In addition, rigidity can be ensured and heat build-up can be reduced. By making the carbon black 100 parts by mass or less, low rolling resistance can be ensured. Two or more types of carbon black may be used in combination.

[0031] The rubber composition for tires can be compounded with silica, which can improve wet grip performance and reduce heat generation. Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc., which may be used alone or in combination of two or more. Surface-treated silica, in which the surface of the silica is treated with a silane coupling agent, may also be used.

[0032] The rubber composition for tires is preferably blended with a silane coupling agent together with silica, and the dispersibility of the silica can be improved. The silane coupling agent can be of a type that is usually blended together with silica. The silane coupling agent is preferably blended in an amount of 5 to 15 mass %, more preferably 8 to 12 mass %, of the amount of silica.

[0033] The rubber composition for tires may contain various additives that are generally used in rubber compositions for tires, such as vulcanizing or crosslinking agents, vulcanization accelerators, antioxidants, plasticizers, processing aids, liquid polymers, and thermosetting resins, within the range that does not impair the object of the present invention. Furthermore, such additives can be kneaded by a general method to prepare a rubber composition for tires, and can be used for vulcanization or crosslinking. The amount of these additives may be a conventional amount, as long as it does not go against the object of the present invention.

[0034] Studless tires and rubber composition for studless tires In a rubber composition for tires that is suitable for forming the tread portion of a studless tire or a studded tire and that solves the problems of the present invention, the diene rubber preferably contains natural rubber and butadiene rubber, and the diene rubber preferably has an average glass transition temperature of −100° C. to −80° C. Also, 10 to 90 parts by mass of silica may be blended with 100 parts by mass of the diene rubber.

[0035] The butadiene rubber content is preferably 40% by mass or more, and more preferably 45 to 80% by mass, per 100% by mass of diene rubber. By containing the butadiene rubber in such a range, performance on ice can be ensured.

[0036] The natural rubber content is preferably 20 to 65 mass %, more preferably 30 to 55 mass %, of 100 mass of diene rubber. By containing the natural rubber in such a range, tire durability can be ensured.

[0037] The average glass transition temperature of the diene rubber is preferably −100° C. to −80° C., more preferably −90° C. to −80° C. By setting the average glass transition temperature within such a range, it is possible to ensure tire durability and on-ice performance. In this specification, the average glass transition temperature of the diene rubber can be calculated from the glass transition temperature of each diene rubber contained and the weighted average of the respective contents.

[0038] A rubber composition for tires suitable for studless tires or stud tires may contain silica in an amount of preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, per 100 parts by mass of diene rubber. By containing silica in such a range, tire durability can be secured while ensuring wet grip performance.

[0039] A rubber composition for tires suitable for studless tires or stud tires preferably contains 40% by mass or more of butadiene rubber in 100% by mass of diene rubber, and further contains 45 parts by mass or more of plasticizer per 100 parts by mass of diene rubber. By adding 45 parts by mass or more of plasticizer, it is possible to improve the performance on ice. The plasticizer is more preferably added in an amount of 47 to 80 parts by mass, and even more preferably 49 to 70 parts by mass. Examples of the plasticizer include natural oil, synthetic oil, and liquid rubber.

[0040] Rubber composition for winter tires In a rubber composition for tires that is suitable for forming the tread portion of a winter tire and that solves the problems of the present invention, the diene rubber preferably contains a styrene-butadiene rubber and a butadiene rubber, and the diene rubber preferably has an average glass transition temperature of −100° C. to −50° C. Also, it is preferable that 90 to 180 parts by mass of silica is blended with 100 parts by mass of the diene rubber.

[0041] A suitable styrene butadiene rubber is a high Tg type styrene butadiene rubber having a glass transition temperature of -50°C or higher. Such a high Tg type styrene butadiene rubber is preferably contained in an amount of 60% by mass or more, more preferably 65 to 80% by mass, based on 100% by mass of the diene rubber. By containing 60% by mass or more of the high Tg type styrene butadiene rubber, wet performance is improved, which is preferable.

[0042] The butadiene rubber is preferably contained in an amount of 20 to 40 mass%, more preferably 20 to 35 mass%, per 100 mass of diene rubber. By containing the butadiene rubber in such a range, performance on snow can be ensured.

[0043] The diene rubber preferably has an average glass transition temperature of −100° C. to −50° C., and more preferably −70° C. to −50° C. By setting the average glass transition temperature within such a range, it is possible to ensure wet grip performance and on-snow performance.

[0044] A rubber composition for tires suitable for winter tires may contain 100 parts by mass of diene rubber and preferably 90 to 180 parts by mass, more preferably 95 to 150 parts by mass of silica. By containing silica in such a range, wet grip performance can be ensured.

[0045] Rubber composition for all-season tires In the rubber composition for tires, which is suitable for forming the tread portion of an all-season tire and solves the problems of the present invention, the diene rubber containing the styrene-butadiene rubber preferably has an average glass transition temperature of −80° C. to −40° C. Also, it is preferable to compound 10 to 90 parts by mass of silica to 100 parts by mass of the diene rubber.

[0046] In 100 mass of diene rubber, the styrene butadiene rubber is preferably contained in an amount of 50 mass% or more, more preferably 50 to 85 mass%, and more preferably 55 to 80 mass%. By containing the styrene butadiene rubber in such a range, wet grip performance can be ensured. As a suitable styrene butadiene rubber, emulsion polymerization styrene butadiene rubber is preferable.

[0047] The diene rubber preferably has an average glass transition temperature of −80° C. to −40° C., more preferably −75° C. to −45° C., and even more preferably −70° C. to −50° C. By keeping the average glass transition temperature within this range, performance on snow can be ensured.

[0048] A rubber composition for tires suitable for all-season tires may contain 10 to 90 parts by mass, and more preferably 20 to 80 parts by mass, of silica per 100 parts by mass of diene rubber. By containing silica in such a range, it is possible to ensure wet grip performance and tire durability.

[0049] Rubber composition for high performance or racing tires In the rubber composition for tires, which is suitable for forming the tread portion of high-performance tires and race tires and solves the problems of the present invention, the diene rubber containing styrene-butadiene rubber preferably has an average glass transition temperature of −50° C. to −20° C. Also, it is preferable to compound 90 to 180 parts by mass of silica to 100 parts by mass of the diene rubber.

[0050] The styrene-butadiene rubber is preferably contained in an amount of 30% by mass or more, more preferably 40 to 95% by mass, based on 100% by mass of the diene rubber. By containing the styrene-butadiene rubber in such a range, dry grip can be improved.

[0051] The diene rubber preferably has an average glass transition temperature of −50° C. to −20° C., and more preferably −40° C. to −30° C. By setting the average glass transition temperature within this range, dry grip performance can be ensured.

[0052] A rubber composition for tires suitable for high performance tires and race tires may contain 90 to 180 parts by mass, more preferably 95 to 150 parts by mass, of silica per 100 parts by mass of diene rubber. By containing silica in such a range, wet grip performance can be ensured.

[0053] Rubber composition for fuel-efficient tires In the rubber composition for tires, which is suitable for forming the tread portion of a fuel-efficient tire having excellent fuel efficiency performance and which solves the problems of the present invention, the diene rubber containing styrene-butadiene rubber preferably has an average glass transition temperature of −50° C. to −20° C. Also, it is preferable that 100 parts by mass of the diene rubber contains 10 to 90 parts by mass of silica.

[0054] A suitable styrene butadiene rubber is a high Tg type styrene butadiene rubber having a glass transition temperature of -50°C or higher. Such a high Tg type styrene butadiene rubber is preferably contained in 70% by mass or more, more preferably 75 to 95% by mass, based on 100% by mass of the diene rubber. By containing 70% by mass or more of the high Tg type styrene butadiene rubber, wet performance is improved, which is preferable.

[0055] The average glass transition temperature of the diene rubber including the styrene-butadiene rubber is preferably −50° C. to −20° C., and more preferably −40° C. to −30° C. By setting the average glass transition temperature within such a range, it is possible to ensure low rolling resistance while ensuring wet grip performance.

[0056] A rubber composition for tires suitable for fuel-efficient tires may contain 100 parts by mass of diene rubber and preferably 10 to 90 parts by mass, more preferably 20 to 80 parts by mass of silica. By containing silica in such a range, wet grip performance can be ensured while low rolling resistance can be ensured.

[0057] In the rubber composition for tires, the diene rubber preferably contains at least one modified styrene-butadiene rubber selected from the following modified SBR1 and modified SBR2. Modified SBR1: Modified styrene-butadiene rubber 1 produced by a production method including the following steps A, B, and C in this order, having an aromatic vinyl unit content of 38 to 48 mass%, a vinyl bond content of 20 to 35 mass%, and a weight average molecular weight of 500,000 to 800,000. Step A: A step of polymerizing a monomer mixture containing isoprene and aromatic vinyl to form a polymer block A having an active end, the polymer block A having an isoprene unit content of 80 to 95 mass%, an aromatic vinyl unit content of 5 to 20 mass%, and a weight average molecular weight of 500 to 15,000. Step B: A step of mixing the polymer block A with a monomer mixture containing 1,3-butadiene and an aromatic vinyl to continue the polymerization reaction, thereby forming a polymer block B having an active end in a continuous state with the polymer block A, thereby obtaining a conjugated diene-based polymer chain having an active end, which includes the polymer block A and the polymer block B. Step C: A step of reacting the active terminal of the conjugated diene polymer chain with a polyorganosiloxane represented by the following formula (1): [ka] (In formula (1), R 1 ~R 8 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. X 1 and X 4 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 2 is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, 2 may be the same or different. X 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3 When there are a plurality of, they may be the same or different. m is an integer of 3 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200.) Modified SBR2: Modified styrene butadiene rubber 2 produced by a production method including: a first step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; a second step of adding and reacting the polyorganosiloxane represented by the formula (1) to the conjugated diene polymer chain having an active end in a ratio of 1 mol or more calculated as the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane per 1 mol of the polymerization initiator used in the first step; and a third step of reacting the conjugated diene polymer chain reacted with the polyorganosiloxane obtained in the second step with a compound represented by the following formula (2). [ka] (In formula (2), R 9 is a hydrocarbyl group, A 1 is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane, and A 2 is a monovalent group containing a nitrogen atom (excluding groups containing an oxygen atom), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

[0058] The above-mentioned rubber composition for tires is preferably a rubber composition for tire treads, and can be used to favorably configure the tread portion of a tire. A tire having a tread portion configured with the rubber composition for tires of the present invention can achieve both wet grip performance and abrasion resistance. The tire may be either a pneumatic tire or a non-pneumatic tire.

[0059] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples. EXAMPLES

[0060] Table 1 shows the properties of various resins, including the rosin-based resin, used in the examples. [Table 1]

[0061] In Table 1, the types of resin 1 to resin 5 are as follows. Resin 1: Aromatic modified terpene resin, TO-125 manufactured by Yasuhara Chemical Co., Ltd. Resin 2: C5 / C9 resin, Tosoh L-90 Resin 3: Maleic acid rosin resin, AQ-90 manufactured by Harima Chemicals Resin 4: Rosin ester resin, PC-PE-590 manufactured by Arakawa Chemical Industries, Ltd. Resin 5: Rosin ester resin, Sylvatraxx 2097 from Kraton Polymer

[0062] The rubber compositions for tires (Examples 1-17, Reference Examples 1-8, Comparative Examples 1-17) having the common compounding of the compounding agents shown in Table 10 and the compoundings shown in Tables 2-9 were kneaded with the components other than sulfur and vulcanization accelerator in a 1.7 L internal Banbury mixer for 5 minutes, then discharged from the mixer and cooled at room temperature. The resulting mixture was put into the above-mentioned 1.7 L internal Banbury mixer, and the sulfur and vulcanization accelerator were added and mixed to prepare the rubber composition for tires. The compounding amounts of the compounding agents shown in Table 10 are shown in parts by mass relative to 100 parts by mass of the diene rubber shown in Tables 2-9.

[0063] The rubber composition for tires obtained was used to measure the vulcanization rate (T95) by the following method. The rubber composition for tires obtained was also used to prepare a vulcanized rubber sheet by vulcanizing it in a mold of 15 cm x 15 cm x 0.2 cm at 160°C for 20 minutes, and the dynamic viscoelasticity was measured by the following method to be used as an index of wet grip property. Abrasion resistance was also evaluated.

[0064] Vulcanization speed (T95) Using the obtained rubber composition for tires, t95 time (min) was measured under conditions of amplitude 1 degree and 160°C using a vibration type disk vulcanization tester in accordance with JIS K6300. The obtained results are shown in the "vulcanization speed (T95)" column of Tables 2 to 9, with the value of Reference Example 1 set to 100 in Table 2, the value of Reference Example 2 set to 100 in Table 3, the value of Reference Example 3 set to 100 in Table 4, the value of Reference Example 4 set to 100 in Table 5, the value of Reference Example 5 set to 100 in Table 6, the value of Reference Example 6 set to 100 in Table 7, the value of Reference Example 7 set to 100 in Table 8, and the value of Reference Example 8 set to 100 in Table 9. The smaller the index, the faster the vulcanization speed and the more excellent the vulcanization characteristics.

[0065] Wet grip The dynamic viscoelasticity of the vulcanized rubber sheet obtained above was measured with a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., with an initial strain of 10%, an amplitude of ±2%, and a frequency of 20 Hz, and tan δ at 0 ° C. was obtained. The results obtained are shown in the "wet performance" column of Tables 2 to 9, with the value of Reference Example 1 set to 100 in Table 2, the value of Reference Example 2 set to 100 in Table 3, the value of Reference Example 3 set to 100 in Table 4, the value of Reference Example 4 set to 100 in Table 5, the value of Reference Example 5 set to 100 in Table 6, the value of Reference Example 6 set to 100 in Table 7, the value of Reference Example 7 set to 100 in Table 8, and the value of Reference Example 8 set to 100 in Table 9. The larger the index, the better the wet grip performance. An index of 97 or more is considered to be within the acceptable range.

[0066] Abrasion resistance The vulcanized rubber sheet obtained above was measured for wear loss at a temperature of 20°C and a slip rate of 50% using a Lambourn wear tester (manufactured by Iwamoto Seisakusho) in accordance with JIS K6264-1, 2:2005. The reciprocal of each wear loss was calculated, and the results were shown in the "wear resistance" column of Tables 2 to 9, with the value of Reference Example 1 set to 100 in Table 2, the value of Reference Example 2 set to 100 in Table 3, the value of Reference Example 3 set to 100 in Table 4, the value of Reference Example 4 set to 100 in Table 5, the value of Reference Example 5 set to 100 in Table 6, the value of Reference Example 6 set to 100 in Table 7, the value of Reference Example 7 set to 100 in Table 8, and the value of Reference Example 8 set to 100 in Table 9. The larger the index, the smaller the wear loss and the better the wear resistance. An index of 97 or more is considered to be within the acceptable range.

[0067] [Table 2]

[0068] [Table 3]

[0069] [Table 4]

[0070] [Table 5]

[0071] [Table 6]

[0072] [Table 7]

[0073] [Table 8]

[0074] [Table 9]

[0075] In Tables 2 to 9, the types of raw materials used are as follows. NR: Natural rubber, SIR-20 made by PT.KIRANA SAPTA, glass transition temperature is -65℃ SBR-1: Styrene butadiene rubber, Asahi Kasei's Tufden E581, glass transition temperature is -28℃ SBR-2: Emulsion polymerized styrene butadiene rubber, Nipol 1723 manufactured by Nippon Zeon Co., Ltd., glass transition temperature is -53℃

[0076] SBR-3: Modified styrene-butadiene rubber according to claim 21, which has a polyorganosiloxane group represented by formula (1) and has a glass transition temperature of -25°C; Cyclohexane (35g), tetramethylethylenediamine (1.4mmol), and n-butyllithium (4.3mmol) were added to a nitrogen-substituted 100mL ampoule. Isoprene (21.6g) and styrene (3.1g) were then slowly added, and the mixture was reacted for 120 minutes in the ampoule at 50°C to obtain a polymer block A having an active terminal. Next, cyclohexane (4000g), 1,3-butadiene (474.0g), and styrene (126.0g) were charged in a stirrer-equipped autoclave under a nitrogen atmosphere, and the polymer block A having an active terminal obtained above was added in its entirety, and polymerization was initiated at 50°C. After it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, polyorganosiloxane A represented by the formula (1) (wherein n is 0, X 1 , X 4 , R 1 ~R 3 and R 5 ~R 8 is a methyl group, m is 80, k is 120, and X 2is a 3-glycidyloxypropyl group.) was added in the form of a xylene solution with a concentration of 20% by mass so that the content of epoxy groups was 1.42 mmol (equivalent to 0.33 times the molar amount of n-butyl lithium used), and reacted for 30 minutes. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the molar amount of n-butyl lithium used to obtain a solution containing a specific conjugated diene rubber. A small amount of an antioxidant (Irganox 1520, manufactured by BASF) was added to this solution, and solid rubber was collected by a steam stripping method. The obtained solid rubber was dehydrated by a roll and dried in a dryer to obtain modified SBR1 (SBR-3).

[0077] SBR-4: Modified styrene-butadiene rubber according to claim 21, which has a polyorganosiloxane group represented by formula (1) and a compound represented by formula (2) and has a glass transition temperature of -29°C; 50.0g of cyclohexane and 0.66mmol of tetramethylethylenediamine were added to a nitrogen-substituted 100ml ampoule, and 6.6mmol of n-butyllithium was further added. Then, 11.61g of isoprene and 0.87g of styrene were slowly added, and the mixture was reacted for 120 minutes in the ampoule at 50°C to obtain a polymer block B having an active terminal. Next, 4000g of cyclohexane, 11.1mmol of tetramethylethylenediamine, 393g of 1,3-butadiene, and 207g of styrene were charged in a stirrer-equipped autoclave under a nitrogen atmosphere, and the entire amount of the polymer block B having an active terminal obtained above was added, and polymerization was started at 40°C. After 10 minutes had elapsed since the start of polymerization, 337.0 g of 1,3-butadiene and 63.0 g of styrene were added continuously over a period of 40 minutes. The maximum temperature during the polymerization reaction was 60°C. After the continuous addition was completed, the polymerization reaction was continued for another 20 minutes. After it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, polyorganosiloxane A represented by the above formula (1) (wherein n is 0 and X 1 , X 4 , R 1 ~R 3 and R 5 ~R 8is a methyl group, m is 80, k is 120, and X 2 is a 3-glycidyloxypropyl group.) was added in a xylene solution of 40% by mass concentration (1.1 times the molar amount of n-butyllithium used, calculated as the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane), and reacted for 30 minutes. Next, 6.6 mmol of 3-(2-aminoethylamino)propyltrimethoxysilane (1.0 times the molar amount of n-butyllithium used) was added, and reacted for 10 minutes. After that, as a polymerization terminator, methanol was added in an amount equivalent to twice the molar amount of n-butyllithium used to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent, relative to 100 parts of the conjugated diene rubber, and the solvent was removed by steam stripping, and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid modified SBR2 (SBR-4).

[0078] BR: Butadiene rubber, Zeon Nipol 1220, glass transition temperature -106℃ Carbon black: Cabot N330 Silica: Solvay ZEOSIL 1165MP Resin 1 to Resin 5: As shown in Table 1 Aroma oil: Showa Shell Sekiyu Extract No. 4S Coupling agent: Silane coupling agent, Evonik Degussa Si69, bis(triethoxysilylpropyl)tetrasulfide

[0079] [Table 10]

[0080] In Table 10, the types of raw materials used are as follows: Processing aid: Struktol HT207 Anti-aging agent: EASTMAN 6PPD Wax: OZOACE-0015 made by Nippon Seiro Co., Ltd. Zinc oxide: 3 types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. Stearic acid: NOF Corporation beads stearic acid YR Vulcanization accelerator-1: Noccela CZ-G manufactured by Ouchi Shinko Chemical Co., Ltd. Vulcanization accelerator-2: Sumitomo Chemical's Soxinol DG Sulfur: Shikoku Chemical Industry Co., Ltd.'s Myucron OT-20

[0081] As is clear from Table 2, it was confirmed that the rubber compositions for tires of Examples 1 and 2 were excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 1 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 1, but the wet grip property and abrasion resistance cannot be sufficiently improved. The rubber composition for tires of Comparative Example 2 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 1, but is inferior in wet grip properties and abrasion resistance. In the rubber composition for a tire in Comparative Example 3, the rosin-based resin exceeded 50 parts by mass, and therefore the abrasion resistance was rather deteriorated.

[0082] As is clear from Table 3, it was confirmed that the rubber compositions for tires of Examples 3 to 5, which are suitable for studless tires and stud tires, were excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 4 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 2, but the wet grip property and abrasion resistance cannot be sufficiently improved. The rubber composition for tires of Comparative Example 5 was formulated with a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 2, but the abrasion resistance was deteriorated.

[0083] As is clear from Table 4, it was confirmed that the rubber compositions for tires of Examples 6 to 8, which are suitable for winter tires, were excellent in wet grip performance and abrasion resistance. The rubber composition for tires of Comparative Example 6 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 3, but has poor wet grip properties. The rubber composition for tires of Comparative Example 7 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 3, but is inferior in wet grip properties and abrasion resistance.

[0084] As is clear from Table 5, it was confirmed that the rubber compositions for tires of Examples 9 to 11, which are suitable for all-season tires, were excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 8 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 4, but has poor wet grip properties. The rubber composition for tires of Comparative Example 9 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 4, but is inferior in wet grip property and abrasion resistance.

[0085] As is clear from Table 6, it was confirmed that the rubber compositions for tires of Examples 12 and 13, which are suitable for high-performance tires and race tires, were excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 10 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 5, but has poor wet grip properties. The rubber composition for tires of Comparative Example 11 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 5, but is inferior in wet grip properties and abrasion resistance.

[0086] As is clear from Table 7, it was confirmed that the tire rubber compositions of Examples 14 and 15, which are suitable for fuel-efficient tires, were excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 12 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 6, but has poor wet grip properties. The rubber composition for tires of Comparative Example 13 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 6, but is inferior in wet grip property and abrasion resistance.

[0087] As is clear from Table 8, it was confirmed that the rubber composition for a tire of Example 16 was excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 14 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 7, but is inferior in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 15 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 7, but is inferior in wet grip property and abrasion resistance.

[0088] As is clear from Table 9, it was confirmed that the rubber composition for a tire of Example 17 was excellent in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 16 contains a C5 / C9 resin instead of the aromatic modified terpene resin of Reference Example 8, but is inferior in wet grip property and abrasion resistance. The rubber composition for tires of Comparative Example 17 contains a maleic acid modified rosin resin instead of the aromatic modified terpene resin of Reference Example 8, but is inferior in wet grip property and abrasion resistance.

Claims

1. A mixture of 100 parts by mass of diene rubber and 0.5 to 50 parts by mass of rosin resin, the diene rubber and the rosin resin being blended in a mass ratio of 1:1, the difference Tga-Tgm between the calculated glass transition temperature Tga of the mixture, which is calculated as a weighted average value of the glass transition temperatures and mass ratios of the diene rubber and the rosin resin, and the measured glass transition temperature Tgm of the mixture, is 5 to 50°C, and the rosin resin is a rosin ester resin. the rosin ester resin has a softening point of 90 to 96°C and an acid value of 8.2 to 15 mgKOH / g, the rosin ester resin has aliphatic units derived from aliphatic hydrocarbons and aromatic units derived from aromatic hydrocarbons, the mass ratio of the aliphatic units to the aromatic units (aliphatic units / aromatic units) being 92 / 8 to 98 / 2, and the ratio Tg / Mz of the glass transition temperature Tg [°C] of the rosin ester resin to the Z-average molecular weight Mz [-] is 0.03 or more and 0.07 or less.

2. 2. The rubber composition for tires according to claim 1, wherein the diene rubber comprises natural rubber and butadiene rubber, and the diene rubber has an average glass transition temperature of -100°C to -80°C.

3. The rubber composition for tires according to claim 2, wherein 10 to 90 parts by mass of silica are blended with 100 parts by mass of the diene rubber.

4. 4. The rubber composition for tires according to claim 2, further comprising 45 parts by mass or more of a plasticizer per 100 parts by mass of the diene rubber.

5. 2. The rubber composition for tires according to claim 1, wherein the diene rubber comprises a styrene-butadiene rubber and a butadiene rubber, and the diene rubber has an average glass transition temperature of -100°C to -50°C.

6. The rubber composition for tires according to claim 5, wherein 90 to 180 parts by mass of silica are blended with 100 parts by mass of the diene rubber.

7. 7. The rubber composition for tires according to claim 5, comprising 60% by mass or more of a styrene-butadiene rubber having a glass transition temperature of -50°C or higher, based on 100% by mass of the diene rubber.

8. 2. The rubber composition for tires according to claim 1, wherein the diene rubber comprises a styrene-butadiene rubber, and the diene rubber has an average glass transition temperature of -80°C to -40°C.

9. The rubber composition for tires according to claim 8, wherein 10 to 90 parts by mass of silica are blended with 100 parts by mass of the diene rubber.

10. The rubber composition for tires according to claim 8 or 9, comprising 50% by mass or more of emulsion-polymerized styrene-butadiene rubber based on 100% by mass of the diene rubber.

11. 2. The rubber composition for tires according to claim 1, wherein the diene rubber comprises a styrene-butadiene rubber, and the diene rubber has an average glass transition temperature of -50°C to -20°C.

12. The rubber composition for tires according to claim 11, wherein 90 to 180 parts by mass of silica are blended with 100 parts by mass of the diene rubber.

13. The rubber composition for tires according to claim 11 or 12, comprising 30% by mass or more of the styrene-butadiene rubber based on 100% by mass of the diene rubber.

14. The rubber composition for tires according to claim 11, wherein 10 to 90 parts by mass of silica are blended with 100 parts by mass of the diene rubber.

15. 15. The rubber composition for tires according to claim 11, comprising 70% by mass or more of a styrene-butadiene rubber having a glass transition temperature of -50°C or higher, based on 100% by mass of the diene rubber.

16. 2. The rubber composition for tires according to claim 1, wherein the diene rubber comprises at least one modified styrene-butadiene rubber selected from the group consisting of modified SBR1 and modified SBR2. Modified SBR1; A modified styrene-butadiene rubber 1 is produced by a production method including the following steps A, B, and C in this order, the modified styrene-butadiene rubber having an aromatic vinyl unit content of 38 to 48 mass%, a vinyl bond content of 20 to 35 mass%, and a weight average molecular weight of 500,000 to 800,000. Step A: A step of polymerizing a monomer mixture containing isoprene and an aromatic vinyl to form a polymer block A having an active end, the polymer block A having an isoprene unit content of 80 to 95 mass%, an aromatic vinyl unit content of 5 to 20 mass%, and a weight average molecular weight of 500 to 15,000. Step B: A step of mixing the polymer block A with a monomer mixture containing 1,3-butadiene and an aromatic vinyl to continue the polymerization reaction, thereby forming a polymer block B having an active end in a continuous state with the polymer block A, thereby obtaining a conjugated diene-based polymer chain having an active end, which includes the polymer block A and the polymer block B. Step C: A step of reacting the active terminal of the conjugated diene polymer chain with a polyorganosiloxane represented by the following formula (1). 【Chemistry 1】 (In formula (1), R 1 ~R 8 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. X 1 and X 4 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 2 is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms, 2 may be the same or different. X 3 is a group containing 2 to 20 repeating alkylene glycol units, X 3 When there are a plurality of, they may be the same or different. m is an integer of 3 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200. Modified SBR2; A modified styrene-butadiene rubber 2 produced by a production method including: a first step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active end; a second step of adding and reacting the polyorganosiloxane represented by the formula (1) to the conjugated diene polymer chain having an active end in a ratio of 1 mol or more calculated as the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane per 1 mol of the polymerization initiator used in the first step; and a third step of reacting the conjugated diene polymer chain reacted with the polyorganosiloxane obtained in the second step with a compound represented by the following formula (2). 【Chemistry 2】 (In formula (2), R 9 is a hydrocarbyl group, A 1 is a group capable of reacting with a reaction residue formed by the reaction of a conjugated diene polymer chain having an active terminal with a polyorganosiloxane, and A 2 is a monovalent group containing a nitrogen atom (excluding groups containing an oxygen atom). p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4.

17. The rubber composition for tires according to any one of claims 1 to 3, 5, 6, 8, 9, 11, 12, 14 and 16, which is for use in tire treads.

18. A tire comprising the rubber composition for tires according to any one of claims 1 to 3, 5, 6, 8, 9, 11, 12, 14 and 16.

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