Rubber composition for tire, and tire

Abstract

To provide a rubber composition for a tire excellent in wet grip performance.SOLUTION: A rubber composition for a tire includes a rubber constituent including a solution polymerization styrene butadiene rubber, a filler including silica, a resin, and a low temperature plasticizer having an SP value of 8.0 to 8.5 (cal / cm3)1 / 2. An amount of the silica is 100 to 300 pts.mass, an amount of the resin is 40 to 100 pts.mass, and an amount of the low temperature plasticizer is 15 to 50 pts.mass to 100 pts.mass of the rubber constituent. A ratio of the silica in the filler is 80 mass% or more. A mass ratio (silica / low temperature plasticizer) of the amount of the silica to the amount of the low temperature plasticizer is 5.00 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for a tire and a tire using the same. [Background technology]

[0002] In order to improve the wet grip performance of tires, a technique of compounding silica or resin into a rubber composition for forming a tread is known (see, for example, Patent Documents 1 and 2). However, when a large amount of silica is compounded into the rubber composition in order to further improve the wet grip performance, the silica tends to aggregate, making it difficult to obtain sufficient wet grip performance.

[0003] Patent Document 3 proposes that, in order to impart excellent wet grip performance, a large amount of silica and carbon black are blended as fillers together with other inorganic fillers, and further a specific resin and a low-temperature plasticizer are blended.

[0004] Patent Document 4 proposes blending a large amount of resin and a low-temperature plasticizer in order to improve grip performance on dry roads at the beginning and during driving while maintaining sufficient abrasion resistance. However, Patent Document 4 suggests that carbon black is preferable as a filler from the viewpoint of abrasion resistance, and does not disclose any examples in which silica is blended. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-003254 [Patent Document 2] Japanese Patent Application Publication No. 2019-182920 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-277307 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-037544 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, Patent Document 3 describes compounding a large amount of a filler containing silica, as well as compounding a resin and a low-temperature plasticizer. However, the rubber composition described in Patent Document 3 contains a considerable amount of carbon black and other inorganic fillers in addition to silica, and the ratio of silica in the filler is low. Therefore, there is still room for improvement in wet grip performance when a large amount of silica is compounded and the ratio of silica in the filler is high.

[0007] In view of the above, an object of an embodiment of the present invention is to provide a rubber composition for a tire that has excellent wet grip performance. [Means for solving the problem]

[0008] The present invention includes the embodiments shown below. [1] A rubber component containing solution-polymerized styrene butadiene rubber, a filler containing silica, a resin, and an SP value of 8.0 to 8.5 (cal / cm 3 ) 1 / 2 the amount of the silica is 100 to 300 parts by mass relative to 100 parts by mass of the rubber component, the amount of the resin is 40 to 100 parts by mass relative to 100 parts by mass of the rubber component, the amount of the low-temperature plasticizer is 15 to 50 parts by mass relative to 100 parts by mass of the rubber component, a ratio of the silica in the filler is 80% by mass or more, and a mass ratio of the amount of the silica to the amount of the low-temperature plasticizer (silica / low-temperature plasticizer) is 5.00 or more. [2] The rubber composition for tires according to [1], wherein the solution-polymerized styrene-butadiene rubber includes a solution-polymerized styrene-butadiene rubber having a glass transition temperature of −20° C. or higher. [3] The rubber composition for a tire according to [1] or [2], wherein the softening point of the resin is 100°C or lower. [4] The rubber composition for a tire according to any one of [1] to [3], wherein the resin contains a styrene-based resin. [5] A tire having a tread formed from the rubber composition for a tire according to any one of [1] to [4]. [Effects of the Invention]

[0009] According to an embodiment of the present invention, a rubber composition for a tire having excellent wet grip performance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0010] The rubber composition for a tire according to the present embodiment (hereinafter also simply referred to as "rubber composition") comprises a rubber component containing solution-polymerized styrene-butadiene rubber, a filler containing silica, a resin, and a rubber component having an SP value of 8.0 to 8.5 (cal / cm 3 ) 1 / 2 and a low temperature plasticizer which is

[0011] Solution-polymerized styrene-butadiene rubber (SSBR) is a styrene-butadiene rubber obtained by anionic polymerization in an organic solvent. SSBR may be modified SSBR, in which the terminals or main chain are modified, or unmodified SSBR. Preferably, the SSBR contains modified SSBR. In one embodiment, the ratio of modified SSBR in the SSBR is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, and may be 100% by mass.

[0012] The modified SSBR is an SSBR modified by introducing a functional group into the terminal and / or main chain. The functional group preferably contains an oxygen atom and / or a nitrogen atom, and examples thereof include at least one selected from the group consisting of an amino group, a hydroxy group, an alkoxy group, an alkoxysilyl group, an epoxy group, and a carboxy group. The use of a modified SSBR containing such a functional group can enhance the effect of improving the dispersibility of silica.

[0013] The SSBR preferably used has a glass transition temperature (Tg) of -20°C or higher. That is, the SSBR preferably includes an SSBR having a Tg of -20°C or higher (hereinafter, sometimes referred to as a high Tg SSBR). By using such an SSBR with a high Tg, the effect of improving wet grip performance can be enhanced. In this case, the SSBR may be a high Tg SSBR alone, or a combination of a high Tg SSBR and an SSBR having a Tg of less than -20°C. The glass transition temperature of the high Tg SSBR is more preferably -20°C to 10°C, and even more preferably -15°C to 5°C. The high Tg SSBR may be a modified SSBR or an unmodified SSBR, and is preferably a modified SSBR.

[0014] In one embodiment, the proportion of high Tg SSBR in the SSBR is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, and may be 100% by mass.

[0015] In this specification, the glass transition temperature of SSBR is a value measured by differential scanning calorimetry (DSC) in accordance with JIS K6240:2011 at a temperature rise rate of 20°C / min (measurement temperature range: -150°C to 50°C).

[0016] The rubber component may be composed solely of SSBR, or may contain other diene rubbers in addition to SSBR. Here, diene rubber refers to a rubber having repeating units corresponding to diene monomers having conjugated double bonds, and containing carbon-carbon double bonds in the polymer main chain.

[0017] Specific examples of other diene rubbers include natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), emulsion-polymerized styrene butadiene rubber (ESBR), nitrile rubber (NBR), chloroprene rubber (CR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, and styrene-isoprene-butadiene copolymer rubber. These diene rubbers also include those whose terminals or main chains have been modified as necessary (e.g., terminal-modified BR) and those whose rubbers have been modified to impart desired properties (e.g., modified NR). These other diene rubbers may be used alone or in combination of two or more.

[0018] In one embodiment, the proportion of SSBR in the rubber component is preferably 50% by mass or more, more preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass (i.e., SSBR alone).

[0019] The rubber composition according to the present embodiment contains silica as a filler, and it is preferable to use wet silica such as wet precipitation silica or wet gelation silica.

[0020] The nitrogen adsorption specific surface area of ​​silica is not particularly limited, and may be, for example, 100 to 300 m 2 / g is also acceptable, 150-250m 2 / g is also acceptable, 180-220m 2 The nitrogen adsorption specific surface area of ​​silica is the BET specific surface area measured in accordance with the BET method described in JIS K6430:2008.

[0021] The silica content is 100 to 300 parts by mass per 100 parts by mass of the rubber component. By filling the silica at a high level in this manner, wet grip performance can be improved. The silica content is preferably 100 to 200 parts by mass, more preferably 110 to 180 parts by mass, and even more preferably 120 to 150 parts by mass per 100 parts by mass of the rubber component.

[0022] The filler may be silica alone, or may be blended with other fillers such as carbon black and inorganic fillers, preferably carbon black.

[0023] The proportion of silica in the filler is 80% by mass or more. By making the proportion of silica in the entire filler 80% by mass or more in this way, wet grip performance and abrasion resistance can be improved. The proportion of silica in the filler is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more, and may be 100% by mass (i.e., silica alone).

[0024] When carbon black is blended together with silica as a filler, the blending amount of carbon black is not particularly limited as long as the ratio of silica is 80% by mass or more as described above, and may be, for example, 15 parts by mass or less, 10 parts by mass or less, or 3 to 10 parts by mass per 100 parts by mass of the rubber component.

[0025] The carbon black is not particularly limited, and various known types can be used. Specific examples include SAF grade (N100 series), ISAF grade (N200 series), HAF grade (N300 series), FEF grade (N500 series), and GPF grade (N600 series) (all ASTM grades). These grades of carbon black can be used alone or in combination of two or more.

[0026] The rubber composition according to the present embodiment contains 40 to 100 parts by mass of resin per 100 parts by mass of the rubber component. By compounding such a large amount of resin, wet grip performance can be improved. The resin content is preferably 40 to 80 parts by mass, more preferably 45 to 70 parts by mass, and even more preferably 50 to 65 parts by mass per 100 parts by mass of the rubber component.

[0027] From the viewpoint of enhancing the effect of improving wet grip performance, it is preferable to use a resin having a softening point of 100°C or less. The softening point of the resin is more preferably 60°C to 100°C, more preferably 70°C to 95°C, and even more preferably 80°C to 90°C.

[0028] In this specification, the softening point of the resin is a value measured using a ring and ball softening point measuring apparatus in accordance with JIS K6220-1:2015.

[0029] Examples of resins include various thermoplastic resins such as styrene-based resins, terpene-based resins (e.g., polyterpene resins, terpene phenol resins), coumarone-based resins (e.g., coumarone resins, coumarone-indene resins), petroleum resins (e.g., C5-based petroleum resins, C9-based petroleum resins, C5 / C9-based petroleum resins), and rosin-based resins (e.g., natural resin rosin, rosin-modified maleic acid resins), and these may be used alone or in combination of two or more.

[0030] Among these, styrene-based resins are preferred as the resin because they have good compatibility with SSBR and are excellent in improving wet grip performance. That is, in one embodiment, the resin preferably contains a styrene-based resin. The proportion of the styrene-based resin in the resin is preferably 50% by mass or more, more preferably 70% by mass or more, and more preferably 90% by mass or more, and may even be 100% by mass (i.e., styrene-based resin alone).

[0031] Styrenic resins are polymers that use styrene monomers as constituent monomers, and are a general term for polymers of styrene monomers and polymers that contain styrene monomers as the main component (50% by mass or more). Styrenic resins may be homopolymers obtained by polymerizing one type of styrene monomer alone, copolymers obtained by copolymerizing two or more types of styrene monomers, or copolymers of styrene monomers and other monomers that can be copolymerized with them.

[0032] Examples of styrene-based monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, and chlorostyrene.

[0033] Specific examples of styrene-based resins include polystyrene, α-methylstyrene homopolymer, styrene / α-methylstyrene copolymer, styrene-based monomer / aliphatic monomer copolymer, α-methylstyrene / aliphatic monomer copolymer, styrene-based monomer / α-methylstyrene / aliphatic monomer copolymer, etc. Among these, α-methylstyrene-based resins containing α-methylstyrene as a constituent monomer are preferred.

[0034] The rubber composition according to the present embodiment has an SP value (solubility parameter) of 8.0 to 8.5 (cal / cm 3 ) 1 / 2 A low-temperature plasticizer with such an SP value is compounded. Low-temperature plasticizers with such an SP value are thought to have good compatibility with SSBR and therefore improve wet grip performance and abrasion resistance. In detail, without intending to be limited by theory, it is thought that such low-temperature plasticizers enhance the plasticizing effect by alleviating the intermolecular forces that hinder the micro-Brownian motion of the SSBR polymer chains, thereby improving compatibility with SSBR. Furthermore, it is thought that such low-temperature plasticizers not only have good compatibility with SSBR, but also improve silica dispersion due to their polarity (SP value), thereby improving wet grip performance.

[0035] The SP value of low-temperature plasticizers is 8.1 to 8.5 (cal / cm 3 ) 1 / 2 It is preferable that the viscosity is 8.2 to 8.4 (cal / cm 3 ) 1 / 2 is.

[0036] In this specification, the SP value is a value calculated by the method described on pages 71 to 77 of "Practical Polymers for Engineers" by Junji Mukai and Noriyuki Kaneshiro (published by Kodansha on October 1, 1981), and in particular, the value δ [(cal / cm 3 ) 1 / 2 ]. Note that 1 (cal / cm 3 ) 1 / 2 ≒2.05 (MPa) 1 / 2 Therefore, the SP value is 8.0 to 8.5 (cal / cm 3 ) 1 / 2 is 16.4 to 17.4 (MPa) 1 / 2 means.

[0037] The low-temperature plasticizer is a plasticizer having a freezing point of −50° C. or lower. The freezing point of the low-temperature plasticizer is more preferably −60° C. or lower. There is no particular limitation on the lower limit of the freezing point of the low-temperature plasticizer.

[0038] SP value is 8.0-8.5 (cal / cm 3 ) 1 / 2 Specific examples of the low-temperature plasticizer include tris(2-ethylhexyl)phosphate (TOP), bis(2-ethylhexyl)sebacate (DOS), bis(2-ethylhexyl)adipate (DOA), etc. Any one of these may be used alone, or two or more may be used in combination.

[0039] The content of the low-temperature plasticizer is 15 to 50 parts by mass per 100 parts by mass of the rubber component. By having the content of the low-temperature plasticizer be 15 parts by mass or more, it is possible to improve the dispersibility of silica when a highly filled amount of silica as described above is compounded, thereby improving wet grip performance. The content of the low-temperature plasticizer is more preferably 18 to 40 parts by mass, and even more preferably 20 to 30 parts by mass per 100 parts by mass of the rubber component.

[0040] The content of the low-temperature plasticizer is also set as a ratio to the amount of silica as follows: That is, the mass ratio of the amount of silica to the amount of low-temperature plasticizer (silica / low-temperature plasticizer) is 5.00 or more. This prevents the plasticizing effect of the low-temperature plasticizer from becoming excessive, increases the shear force acting during mixing of the rubber composition, and improves the dispersibility of silica. The mass ratio (silica / low-temperature plasticizer) is preferably 5.00 to 15.00, more preferably 5.10 to 10.00, more preferably 5.50 to 8.00, and even more preferably 6.00 to 7.00.

[0041] The rubber composition according to the present embodiment may further contain oil. Examples of oil include mineral oils such as paraffinic oil, naphthenic oil, and aromatic oil, and vegetable oils such as linseed oil, safflower oil, soybean oil, corn oil, castor oil, rapeseed oil, and cottonseed oil. These oils may be used alone or in combination of two or more.

[0042] The oil content is not particularly limited and is, for example, preferably 10 to 150 parts by mass, more preferably 15 to 120 parts by mass, and even more preferably 20 to 100 parts by mass per 100 parts by mass of the rubber component. When an oil-extended rubber is used as the rubber component, the oil content includes the amount of oil contained in the oil-extended rubber.

[0043] In addition to the above components, the rubber composition of the present embodiment may contain various additives that are generally used in rubber compositions, such as a silane coupling agent, zinc oxide, stearic acid, wax, an antioxidant, a vulcanizing agent, and a vulcanization accelerator.

[0044] Examples of the silane coupling agent include a sulfide silane coupling agent, a mercapto silane coupling agent, and a thioester group-containing silane coupling agent. The content of the silane coupling agent is not particularly limited, and may be, for example, 5 to 20 parts by mass or 5 to 15 parts by mass per 100 parts by mass of silica.

[0045] The content of zinc oxide is not particularly limited, and may be, for example, 0 to 10 parts by mass, 0.5 to 7 parts by mass, or 1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0046] The content of stearic acid is not particularly limited, and may be, for example, 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of the rubber component.

[0047] The content of the wax is not particularly limited, and may be, for example, 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of the rubber component.

[0048] Examples of the antioxidant include various antioxidants such as amine-ketone, aromatic secondary amine, monophenol, bisphenol, and benzimidazole antioxidants, any of which may be used alone or in combination of two or more. The content of the antioxidant is not particularly limited, and may be, for example, 0 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of the rubber component.

[0049] As the vulcanizing agent, sulfur is preferably used. The content of the vulcanizing agent is not particularly limited, and may be 0.1 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 3 parts by mass per 100 parts by mass of the rubber component.

[0050] Examples of the vulcanization accelerator include various vulcanization accelerators such as sulfenamide-based, guanidine-based, thiuram-based, and thiazole-based accelerators, and any one of them can be used alone or in combination of two or more. The content of the vulcanization accelerator is not particularly limited, and may be 0.1 to 10 parts by mass, 0.5 to 5 parts by mass, or 1 to 4 parts by mass per 100 parts by mass of the rubber component.

[0051] The rubber composition according to the present embodiment can be prepared by kneading in a conventional manner using a commonly used mixer such as a Banbury mixer, kneader, roll, etc. That is, for example, in a first mixing stage, additives other than the vulcanizing agent and vulcanization accelerator are added and mixed with the rubber component, and then in a final mixing stage, the vulcanizing agent and vulcanization accelerator are added and mixed with the resulting mixture to prepare the rubber composition.

[0052] The rubber composition according to this embodiment can be used for tires. Examples of tires include pneumatic tires of various sizes and for various uses, such as tires for passenger cars and large tires for trucks and buses. Preferably, the rubber composition is used for high-performance tires such as racing tires and UHP (ultra high performance) tires. The rubber composition is preferably used as tread rubber in tires.

[0053] A tire according to one embodiment includes a tread rubber made using the rubber composition. That is, the tire according to one embodiment includes a tread formed from the rubber composition. The tread rubber of the tire may have a two-layer structure of a cap rubber and a base rubber, or a single-layer structure in which the two are integrated. In the case of a single-layer structure, the tread rubber is preferably formed from the rubber composition. In the case of a two-layer structure, the outer cap rubber that comes into contact with the road surface is preferably formed from the rubber composition, but both the cap rubber and the base rubber may be formed from the rubber composition.

[0054] The method for manufacturing a tire is not particularly limited. For example, the rubber composition is extruded into a predetermined shape according to a conventional method to obtain an unvulcanized tread rubber component. The tread rubber component is combined with other tire components to produce an unvulcanized tire (green tire). Thereafter, the tire can be manufactured by vulcanizing and molding at, for example, 140°C to 180°C. [Example]

[0055] Examples of the present invention will be shown below, but the present invention is not limited to these examples.

[0056] The components used in the examples and comparative examples are as follows. SSBR1: Modified SSBR, 37.5 phr oil-extended, "Tufden E581" manufactured by Asahi Kasei Corporation (Tg: -27°C) SSBR2: Unmodified SSBR, 50 phr oil-extended, Asahi Kasei Corporation "Tufden 4850" (Tg: -25°C) SSBR3: Modified SSBR, 37.5 phr oil-extended, "SE6233" manufactured by Sumitomo Chemical Co., Ltd. (Tg: -2°C)

[0057] Silica: Tosoh Silica Corporation's "Nipsil AQ" (nitrogen adsorption specific surface area 205 m 2 / g) Carbon black: "Seast 9" manufactured by Tokai Carbon Co., Ltd. Silane coupling agent: Evonik Japan "Si69"

[0058] Resin 1: Terpene resin, softening point 115°C, Kraton "SYLVATRAXX 4150" Resin 2: α-methylstyrene resin, softening point 85°C, Kraton "SYLVATRAXX 4401"

[0059] Mineral oil: naphthenic oil, ENEOS Corporation "Process NC140" Low-temperature plasticizer 1: Bis[2-(2-butoxyethoxy)ethyl]adipate, "BXA-N" manufactured by Daihachi Chemical Industry Co., Ltd. (SP value: 8.72) Low-temperature plasticizer 2: Tris(2-ethylhexyl)phosphate, "TOP" manufactured by Daihachi Chemical Industry Co., Ltd. (SP value: 8.20) Low-temperature plasticizer 3: Bis(2-ethylhexyl) sebacate, "DOS" manufactured by Daihachi Chemical Industry Co., Ltd. (SP value: 8.39)

[0060] Zinc oxide: "Zinc Oxide No. 1" manufactured by Mitsui Steel Works Co., Ltd. Stearic acid: Kao Corporation's "Lunac S-20" Wax: "OZOACE0355" manufactured by Nippon Seiro Co., Ltd. Anti-aging agent 1: "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent 2: "Antage RD" manufactured by Kawaguchi Chemical Industry Co., Ltd. Vulcanization accelerator 1: "Noccela D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: "Soxinol CZ" manufactured by Sumitomo Chemical Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0061] The evaluation test methods used in the examples and comparative examples are as follows. (1) Wet grip performance A 2mm thick vulcanized rubber sample was subjected to a tensile mode viscoelasticity test using a Toyo Seiki Co., Ltd. viscoelasticity tester at a frequency of 10Hz, static strain of 10%, dynamic strain of 1%, and temperature of 0°C to measure the loss factor tanδ. The tanδ of Comparative Example 1 in Table 1, Comparative Example 2 in Table 2, Comparative Example 5 in Table 3, and Comparative Example 6 in Table 4 are each expressed as an index, with tanδ set to 100. A larger index indicates a larger tanδ, i.e., a larger energy loss, and thus indicates excellent wet grip performance as a tire.

[0062] (2) Abrasion resistance The wear amount of the vulcanized rubber samples was measured using a Lambourn abrasion tester in accordance with JIS K6264-2:2005 under conditions of a load of 3 kg, a slip ratio of 20%, a temperature of 23°C, and a sand dropping rate of 20 g / min. Table 1 shows the wear amount for Comparative Example 1, Table 2 for Comparative Example 2, Table 3 for Comparative Example 5, and Table 4 for Comparative Example 6, and the results are shown as an index with the reciprocal of the wear amount set to 100. A larger index indicates a smaller wear amount and better wear resistance.

[0063] [First Experimental Example] Using a Banbury mixer, first, in the first mixing stage, compounding ingredients excluding sulfur and vulcanization accelerator were added to the rubber component and kneaded (discharge temperature = 155°C) according to the formulation (parts by mass) shown in Table 1. Next, in the final mixing stage, sulfur and vulcanization accelerator were added to the obtained kneaded mixture and kneaded (discharge temperature = 90°C) to prepare a rubber composition.

[0064] In Table 1, "oil (oil extender)" in the formulation is the amount of oil in the oil extender formulated as SSBR1 to 3, and the parts by mass of each of SSBR1 to 3 is the amount as polymer excluding the oil extender. Also, "silica / low-temperature plasticizer" is the mass ratio of the amount of silica to the amount of low-temperature plasticizer. The same applies to Tables 2 to 4.

[0065] Each rubber composition was vulcanized at 160°C for 30 minutes to prepare vulcanized rubber samples of a predetermined shape, and the wet grip performance and abrasion resistance were evaluated. The results are shown in Table 1.

[0066] [Table 1]

[0067] As shown in Table 1, Example 1, in which the silica / low-temperature plasticizer ratio was 5.00, exhibited superior wet grip performance and abrasion resistance compared to Comparative Example 1, in which this ratio was lower. In Examples 2 and 3, SSBR with a higher Tg and Resin 2 with a lower softening point were used compared to Example 1, and further improvements in wet grip performance and abrasion resistance were observed.

[0068] [Second Experimental Example] Rubber compositions were prepared according to the formulation (parts by mass) shown in Table 2 below, except for the same procedures as in Experimental Example 1. Using the obtained rubber compositions, wet grip performance and abrasion resistance were evaluated in the same manner as in Experimental Example 1. The results are shown in Table 2.

[0069] [Table 2]

[0070] As shown in Table 2, Examples 4 to 6, which contained low-temperature plasticizers 2 and 3 with SP values ​​within the specified range, had superior wet grip performance compared to Comparative Example 2, which contained low-temperature plasticizer 1 with an SP value outside the specified range. Furthermore, Examples 5 and 6, which used a styrene-based resin with a lower softening point than Example 4, demonstrated further improvements in wet grip performance. On the other hand, Comparative Example 3 contained low-temperature plasticizer 2 with an SP value within the specified range, but the silica ratio in the filler was low, and therefore no improvement in wet grip performance and abrasion resistance was obtained compared to Comparative Example 2. Comparative Example 4 contained low-temperature plasticizer 2 with an SP value within the specified range, but the silica / low-temperature plasticizer ratio was low, resulting in poorer wet grip performance and abrasion resistance compared to Comparative Example 2.

[0071] [Third Experimental Example] Rubber compositions were prepared according to the formulation (parts by mass) shown in Table 3 below, except for the same procedures as in Experimental Example 1. Using the resulting rubber compositions, wet grip performance and abrasion resistance were evaluated in the same manner as in Experimental Example 1. The results are shown in Table 3.

[0072] [Table 3]

[0073] As shown in Table 3, Examples 7 to 9, which contained low-temperature plasticizers 2 and 3 with SP values ​​within the specified range, had superior wet grip performance and abrasion resistance compared to Comparative Example 5, which contained low-temperature plasticizer 1 with an SP value outside the specified range. Furthermore, Examples 8 and 9 used SSBR with a lower Tg than Example 7, and thus further improvement in wet grip performance was observed.

[0074] [Fourth Experimental Example] Rubber compositions were prepared according to the formulation (parts by mass) shown in Table 4 below, except for the same procedures as in Experimental Example 1. Using the resulting rubber compositions, wet grip performance and abrasion resistance were evaluated in the same manner as in Experimental Example 1. The results are shown in Table 4.

[0075] [Table 4]

[0076] As shown in Table 4, Examples 10 and 11, in which the silica ratio in the filler was 80 mass% or more, exhibited superior wet grip performance and abrasion resistance compared to Comparative Example 6, which had a lower silica ratio. Furthermore, Example 11, in which Resin 2, which had a softening point of 100°C or less, was used, exhibited even greater improvements in wet grip performance and abrasion resistance compared to Example 10.

[0077] The various numerical ranges described in this specification can be arbitrarily combined with their upper and lower limits, and all such combinations are considered to be preferred numerical ranges described in this specification. Furthermore, a numerical range described as "X to Y" means from X to Y.

Claims

1. A rubber component containing solution-polymerized styrene-butadiene rubber, a filler containing silica, a resin, and an SP value of 8.0 to 8.5 (cal / cm ３ ) １／２ a low-temperature plasticizer, the amount of the silica is 100 to 300 parts by mass per 100 parts by mass of the rubber component, the amount of the resin is 40 to 100 parts by mass per 100 parts by mass of the rubber component, the amount of the low-temperature plasticizer is 15 to 50 parts by mass per 100 parts by mass of the rubber component, The ratio of the silica in the filler is 80% by mass or more, the mass ratio of the amount of the silica to the amount of the low-temperature plasticizer (silica / low-temperature plasticizer) is 5.00 or more; Rubber composition for tires.

2. 2. The rubber composition for a tire according to claim 1, wherein the solution-polymerized styrene-butadiene rubber includes a solution-polymerized styrene-butadiene rubber having a glass transition temperature of −20° C. or higher.

3. The rubber composition for a tire according to claim 1, wherein the resin has a softening point of 100°C or lower.

4. The rubber composition for a tire according to claim 1 , wherein the resin comprises a styrene-based resin.

5. A tire having a tread formed from the rubber composition for tires according to any one of claims 1 to 4.

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