Rubber composition and tires

Abstract

Improve the dispersibility of silica and improve low heat generation properties. 【Solution means】The rubber composition according to the embodiment includes a rubber component containing a modified solution-polymerized styrene-butadiene rubber, silica, and a thiuram vulcanization accelerator represented by the following general formula (1). With respect to 100 parts by mass of the rubber component, the content of silica is 80 to 140 parts by mass, and the content of the thiuram vulcanization accelerator is 0.2 to 6 parts by mass. In formula (1), R 1 , R 2 , R 3 and R 4 are each independently a hydrocarbon group having 12 to 20 carbon atoms, which may optionally contain one or more heteroatoms, and R 1 and R 2 , and / or, R 3 and R 4 may each form a heterocyclic group together with the nitrogen atom to which they are attached. 【Chemical formula 1】 JPEG2026103953000006.jpg27147

Description

[Technical Field]

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

[0002] To improve the fuel efficiency of tires, the incorporation of silica as a filler into the rubber composition used in tires is being considered. Silica can contribute to fuel efficiency by improving the low heat generation of the rubber composition. However, silica is generally more difficult to disperse uniformly in the rubber composition compared to carbon black.

[0003] Patent Document 1 discloses the use of thiuram disulfide instead of diphenylguanidine as a vulcanization accelerator in a silica-containing rubber composition, and the thereby increase the Mooney scorch value.

[0004] Patent Document 2 discloses the use of a combination of an alkoxysilane coupling agent having a mercapto group and a thiuram disulfide-based vulcanization accelerator in a silica-containing rubber composition to simultaneously solve the problems of vulcanization delay and silica dispersibility.

[0005] On the other hand, Patent Document 3 discloses that in a rubber composition containing styrene-butadiene rubber, tetrakis(alkyl)thiuram disulfide is incorporated as a vulcanization accelerator for the vulcanization system, and that this does not generate harmful nitrosamines and does not degrade the rubber properties. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2003-535943 [Patent Document 2] International Publication No. 2006 / 028254 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-265686

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] As described above, it is known to incorporate thiuram disulfide as a vulcanization accelerator in a silica-containing rubber composition, but there is still room for improvement in terms of low heat build-up.

[0008] In view of the above points, an embodiment of the present invention aims to provide a rubber composition capable of improving the dispersibility of silica and thus improving low heat build-up, and a tire using the same.

MEANS FOR SOLVING THE PROBLEMS

[0009] The present invention includes the embodiments shown below. [1] A rubber component containing a modified solution-polymerized styrene-butadiene rubber, silica, and a thiuram-based vulcanization accelerator represented by the following general formula (1),

CHEMICAL FORMULA

EFFECTS OF THE INVENTION

[0010] According to embodiments of the present invention, the dispersibility of silica can be improved, thereby improving low heat generation. [Modes for carrying out the invention]

[0011] The rubber composition according to this embodiment comprises a rubber component containing modified solution polymerized styrene-butadiene rubber, silica, and a specific thiram-based vulcanization accelerator.

[0012] Modified solution polymerized styrene-butadiene rubber (SSBR) is a styrene-butadiene rubber obtained by anionic polymerization in an organic solvent, in which functional groups are introduced to the terminals and / or main chain, thereby modifying the rubber with respect to the functional groups.

[0013] The functional group is preferably one that interacts with silica, preferably one that includes at least one selected from the group consisting of oxygen atoms, nitrogen atoms, and silicon atoms, and more preferably one that includes oxygen atoms and / or nitrogen atoms. Specific examples of functional groups include at least one selected from the group consisting of amino groups, hydroxyl groups, alkoxy groups, silyl groups, alkoxysilyl groups, epoxy groups, and carboxyl groups. By using modified SSBR having such functional groups, the effect of improving the dispersibility of silica can be enhanced.

[0014] The rubber component may consist solely of modified SSBR, but it may also contain other diene rubbers along with the modified SSBR. The amount of modified SSBR in 100 parts by mass of the rubber component may be, for example, 30 parts by mass or more, 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, or 100 parts by mass.

[0015] Examples of other diene rubbers include natural rubber (NR), synthetic isoprene rubber (IR), butadiene rubber (BR), unmodified SSBR, emulsion-polymerized styrene-butadiene rubber (ESBR), nitrile rubber (NBR), chloroprene rubber (CR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, and the like. These diene rubbers include those having a modified end or main chain as necessary (for example, end-modified BR), and those modified to impart desired properties (for example, modified NR), which are also included in the concept. Any one of these other diene rubbers may be used alone, or two or more of them may be used in combination. Here, the diene rubber refers to a rubber having a repeating unit corresponding to a diene monomer having a conjugated double bond, and the main chain of the polymer contains a carbon-carbon double bond. The content of the diene rubber in the rubber component is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass.

[0016] In one embodiment, 100 parts by mass of the rubber component may contain 50 to 90 parts by mass of modified SSBR and 10 to 50 parts by mass of at least one selected from the group consisting of NR, IR, and BR (preferably BR). 100 parts by mass of the rubber component may contain 60 to 80 parts by mass of modified SSBR and 20 to 40 parts by mass of at least one selected from the group consisting of NR, IR, and BR (preferably BR).

[0017] Silica is blended as a filler in the rubber composition according to this embodiment. As the silica, it is preferable to use wet silica such as wet precipitated silica and wet gelled silica.

[0018] The nitrogen adsorption specific surface area of the silica is not particularly limited, and may be, for example, 100 to 300 m 2 / g, may be 150 to 250 m 2 / g, or may be 180 to 220 m 2 / g. The nitrogen adsorption specific surface area of the silica is the BET specific surface area measured according to the BET method described in JIS K6430:2008.

[0019] The silica content is 80 to 140 parts by mass per 100 parts by mass of rubber component. By increasing the silica content in this way, the effect of improving low heat generation can be enhanced. The silica content is preferably 90 to 130 parts by mass, and more preferably 100 to 120 parts by mass, per 100 parts by mass of rubber component.

[0020] The filler may be silica alone, or it may be combined with other fillers. Examples of other fillers include carbon black and inorganic fillers, with carbon black being preferred.

[0021] The ratio of silica in the filler is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass (i.e., silica alone).

[0022] When carbon black is blended with silica as a filler, the carbon black content is not particularly limited, but may be 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less per 100 parts by mass of rubber component. Carbon black also functions as a coloring agent to color the rubber composition black, in which case the carbon black content may be 3 to 10 parts by mass per 100 parts by mass of rubber component.

[0023] The carbon black used is not particularly limited, and various known varieties can be used. Specifically, these 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). One or more of these grades of carbon black can be used in combination.

[0024] The rubber composition according to this embodiment contains a thiram-based vulcanization accelerator represented by the following general formula (1) (hereinafter referred to as thiram disulfide (1)) as a vulcanization accelerator. [ka]

[0025] In formula (1), R 1 , R 2 , R 3 and R 4 Each of these is an independent hydrocarbon group having 12 to 20 carbon atoms, which may optionally contain one or more heteroatoms. 1 and R 2 , and / or, R 3 and R 4 These may each form a heterocyclic group with the nitrogen atom to which they are bonded.

[0026] R 1 , R 2 , R 3 and R 4 The hydrocarbon group represented by may be linear or branched, may contain a cyclic hydrocarbon group (e.g., an alicyclic hydrocarbon group or an aryl group), may contain a heterocyclic group, may be saturated or unsaturated. Examples of the heteroatoms include oxygen atoms and nitrogen atoms, which may be included as substituents or may be included in the main chain as ether bonds, ester bonds, or amide bonds. The number of carbon atoms in the hydrocarbon group is preferably 12 to 18.

[0027] R 1 and R 2 They may form a heterocyclic group together with the nitrogen atom to which they are bonded, R 3 and R 4 These may form a heterocyclic group together with the nitrogen atom to which they are bonded. When such a heterocyclic group is formed, the number of carbon atoms is R 1 and R 2 The total is 24 to 40, R 3 and R 4 The total number of carbon atoms is 24 to 40. Specific examples of heterocyclic groups include pyrrolidine rings, pyrrole rings, and piperidine rings. One or more hydrocarbon groups are bonded to these heterocyclic groups as substituents, resulting in the above-mentioned number of carbon atoms in -NR groups. 1 R 2 and -NR 3 R4 Each of these is formed.

[0028] In one embodiment, R 1 , R 2 , R 3 and R 4 Each of these groups is preferably a monovalent saturated hydrocarbon group, more preferably an alkyl group such as a linear or branched dodecyl group, a linear or branched tridecyl group, a linear or branched tetradecyl group, a linear or branched hexadecyl group, a linear or branched heptadecyl group, or a linear or branched octadecyl group, and even more preferably a linear alkyl group.

[0029] The content of thiuram disulfide (1) is 0.2 to 6 parts by mass per 100 parts by mass of the rubber component. Preferably, the content of thiuram disulfide (1) is 0.3 to 5.5 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 0.7 to 4 parts by mass per 100 parts by mass of the rubber component.

[0030] The vulcanization accelerator may be thiuram disulfide (1) alone, or it may be used in combination with other vulcanization accelerators. Examples of other vulcanization accelerators include sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, and thiazole-based vulcanization accelerators.

[0031] In one embodiment, the vulcanization accelerator preferably comprises thiuram disulfide (1) and a sulfenamide-based vulcanization accelerator. Examples of sulfenamide-based vulcanization accelerators include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and N-(tert-butyl)-2-benzothiazole sulfenamide, and any one of these may be used, or two or more may be used in combination.

[0032] When a sulfenamide-based vulcanization accelerator is used in combination, its content is not particularly limited. For example, it may be 0.2 to 6 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. The mass ratio of the thiuram disulfide (1) content to the sulfenamide-based vulcanization accelerator content is not particularly limited. For example, the ratio of thiuram disulfide (1) to sulfenamide-based vulcanization accelerator may be 1 / 6 to 4 / 1, 1 / 5 to 3 / 1, or 1 / 3 to 2 / 1.

[0033] In addition to the above-mentioned components, the rubber composition according to this embodiment may also contain various additives commonly used in rubber compositions, such as silane coupling agents, oils, zinc oxide, stearic acid, antioxidants, waxes, and vulcanizing agents.

[0034] Examples of silane coupling agents include sulfide silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triectosisilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)disulfide, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyl Examples of mercaptosilane coupling agents include pyrtriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyldimethylmethoxysilane, and mercaptoethyltriethoxysilane, as well as thioester group-containing silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane, 3-propionylthiopropyltrimethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. These can be used individually or in combination of two or more.

[0035] The content of the silane coupling agent is not particularly limited, but is preferably 2 to 25% by mass of the silica amount, that is, 2 to 25 parts by mass per 100 parts by mass of silica. More preferably, the content of the silane coupling agent is 5 to 20% by mass of the silica amount.

[0036] The oil content is not particularly limited; for example, it may be 0 to 40 parts by mass, 3 to 30 parts by mass, or 5 to 25 parts by mass per 100 parts by mass of rubber component.

[0037] The zinc oxide content is not particularly limited; for example, it may be 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 rubber component.

[0038] The stearic acid content is not particularly limited; for example, it may be 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 rubber component.

[0039] Examples of anti-aging agents include various anti-aging agents such as amine-ketone, aromatic secondary amine, monophenol, bisphenol, and benzimidazole types, and one or more of these can be used in combination. Among these, aromatic secondary amine anti-aging agents are preferred, and more preferably phenylenediamine anti-aging agents such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine (8PPD), and N-(1,4-dimethylpentyl)-N'-phenyl-p-phenylenediamine (7PPD). The amount of antioxidant is not particularly limited; for example, it may be 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 rubber component.

[0040] The wax content is not particularly limited; for example, it may be 0 to 10 parts by mass, 0.3 to 5 parts by mass, or 0.5 to 3 parts by mass per 100 parts by mass of rubber component.

[0041] Sulfur is preferably used as the vulcanizing agent. The content of the vulcanizing agent is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of rubber component.

[0042] The rubber composition according to this embodiment can be prepared by kneading in accordance with conventional methods using a commonly used mixer such as a Banbury mixer, kneader, or roll. That is, for example, in the first mixing stage, other additives excluding the vulcanizing agent and vulcanization accelerator can be added and mixed with the rubber component, and then, in the final mixing stage, the vulcanizing agent and vulcanization accelerator can be added and mixed with the resulting mixture to prepare the rubber composition.

[0043] The rubber composition according to this embodiment can be used in various rubber components such as tires, vibration-damping rubber, and conveyor belts. Preferably, it is for tires. Examples of tires include passenger car tires, large truck and bus tires, and pneumatic tires of various sizes and applications. In tires, it can be applied to various parts such as the tread, sidewall, and bead.

[0044] In one embodiment, a tire including rubber parts (e.g., tread rubber, sidewall rubber, etc.) made from the above rubber composition is manufactured as follows: The rubber composition is molded into a predetermined shape by conventional methods, for example, by extrusion. The resulting molded product is combined with other parts to produce a green tire. A pneumatic tire can be manufactured by vulcanizing the green tire at, for example, 140 to 180°C.

[0045] A tire according to one embodiment includes a tread rubber made using the above-mentioned rubber composition. The tread rubber of the tire may have a two-layer structure consisting of a cap rubber and a base rubber, or a single-layer structure in which both are integrated. In the case of a single-layer structure, it is preferable that the tread rubber is made of the above-mentioned rubber composition. In the case of a two-layer structure, it is preferable that the outer cap rubber that contacts the road surface is made of the above-mentioned rubber composition, but both the cap rubber and the base rubber may be made of the above-mentioned rubber composition. [Examples]

[0046] The following are examples of the present invention, but the present invention is not limited to these examples.

[0047] The components used in the examples and comparative examples are as follows: • Modified SSBR1: Modified with alkoxy and amino group terminals, manufactured by ENEOS Material Co., Ltd. "HPR350" • Modified SSBR2: "HPR840" manufactured by ENEOS Material Co., Ltd. • Unmodified SSBR: "SL563" manufactured by ENEOS Material Co., Ltd. • BR: "UBEPOL BR150B" manufactured by UBE Elastomer Co., Ltd.

[0048] • Carbon Black: "Seast KH" manufactured by Tokai Carbon Co., Ltd. • Silica: Tosoh Silica Co., Ltd.'s "Nip Seal AQ" (nitrogen adsorption specific surface area 205 m²) 2 / g) • Coupling agent 1: Sulfidesilane coupling agent, "Si69" manufactured by Evonik Industries. • Coupling agent 2: Thioester group-containing silane coupling agent, Momentive Corporation "NXT"

[0049] • Oil: ENEOS Corporation "Process NC140" • Zinc oxide: "Zinc Oxide No. 3" manufactured by Mitsui Mining & Smelting Co., Ltd. • Stearic acid: "Lunaq S-20" manufactured by Kao Corporation • Anti-aging agent 1:77PD, Lanxess "VULKANOX 4030" • Anti-aging agent 2:6 PPD, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Nocrac 6C" • Anti-aging agent 3:8 PPD, manufactured by Seiko Chemical Co., Ltd., "Ozonon 35"

[0050] • Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries, Ltd. • Vulcanization accelerator 1: N-cyclohexyl-2-benzothiazole sulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar CZ-G" • Vulcanization accelerator 2: Diphenylguanidine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar D" • Vulcanization accelerator 3: Tetramethylthiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar TT-P" • Vulcanization accelerator 4: Tetrabenzyl thiuram disulfide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., "Noxellar TBZTD"

[0051] • Sulfurization accelerator 5: Tetralauryl thiura disulfide obtained by the synthesis example 1 below (R in formula (1)) 1 ~R 4 =CH3(CH2) 10 CH2-) Synthesis Example 1: A solution of 35.4 g of dilaurylamine was prepared by dissolving it in 300 ml of THF, and a solution of 18.75 g of potassium hydroxide dissolved in 18.75 ml of water was added dropwise to this solution. After the addition of potassium hydroxide, 18.13 ml of carbon disulfide was added to the solution and the mixture was stirred at room temperature. Saturated iodine-methanol solution was added dropwise to the reaction mixture until the color of the reaction mixture no longer faded. The reaction mixture was then filtered, and the residue was purified by silica gel column chromatography to obtain the desired purified product. The yield was 82% by mass. Regarding the purified reaction product, 13 1C-NMR analysis and mass spectrometry were performed to confirm the acquisition of tetralaurylthioram disulfide.

[0052] • Sulfurization accelerator 6: Tetraoctadecyl thiuram disulfide obtained by the synthesis example 2 below (in formula (1), R 1 ~R4 =CH3(CH2) 16 CH2-) Synthesis Example 2: A solution was prepared by dissolving 52.20 g of dioctadoxylamine in 500 ml of THF, and a solution of 18.75 g of potassium hydroxide dissolved in 18.75 ml of water was added dropwise to this solution. After the addition of potassium hydroxide, 18.13 ml of carbon disulfide was added to the solution and the mixture was stirred at room temperature. Saturated iodine-methanol solution was added dropwise to the reaction mixture until the color of the reaction mixture no longer faded. The reaction mixture was then filtered, and the residue was purified by silica gel column chromatography to obtain the desired purified product. The yield was 85% by mass. Regarding the purified reaction product, 13 13C-NMR analysis and mass spectrometry were performed to confirm that tetraoctadecyl thiuram disulfide was obtained.

[0053] The measurement and evaluation methods in the examples and comparative examples are as follows.

[0054] (1)Hardness For a sample consisting of three 2mm thick vulcanized rubber sheets stacked together, the hardness was measured at 23°C using a Type A durometer in accordance with JIS K6253-3:2012. Table 1 shows the hardness change values ​​(points) relative to Comparative Example 1-1, and Table 2 shows the hardness change values ​​relative to Comparative Example 2-1.

[0055] (2) Low heat generation For vulcanized samples measuring 5 mm in width, 20 mm in length, and 1 mm in thickness, the loss tangent tanδ was measured using a UBM E4000 rheospectrometer in accordance with JIS K6394:2007, under the conditions of static strain (initial strain) of 10%, dynamic strain of 1%, frequency of 10 Hz, and temperature of 60°C (tensile method). Table 1 shows the values ​​for Comparative Example 1-1, and Table 2 shows the values ​​for Comparative Example 2-1, both expressed as an index with a base of 100. A smaller index indicates a smaller tanδ, and therefore less heat generation, superior low heat generation, and thus superior fuel efficiency as a tire.

[0056] (3) Dispersibility For vulcanized samples measuring 5 mm in width, 20 mm in length, and 1 mm in thickness, the storage modulus (E'(0.1) and E'(10)) were measured at dynamic strains of 0.1% and 10% under the conditions of a temperature of 60°C, a frequency of 10 Hz, and a static strain (initial strain) of 10% (tensile method), using a rheospectrometer E4000 manufactured by UBM Co., Ltd., and the Payne effect (δE' = E'(0.1) - E'(10)) was calculated. Table 1 shows the values ​​for Comparative Example 1-1, and Table 2 shows the values ​​for Comparative Example 2-1, both expressed as an index with a base of 100. A smaller index indicates a smaller δE' and superior filler dispersibility.

[0057] [First Experimental Example] Using a Banbury mixer, according to the formulation (parts by mass) shown in Table 1 below, first, in the first mixing stage, compounding agents excluding sulfur and vulcanization accelerator were added to the rubber component and kneaded (discharge temperature = 155°C). Next, in the final mixing stage, sulfur and vulcanization accelerator were added to the resulting knead and kneaded (discharge temperature = 90°C) to prepare the rubber composition.

[0058] Table 1 shows that Comparative Example 1-1 was used as the standard formulation, and the amount of vulcanization accelerator added was adjusted to achieve approximately the same hardness as the standard formulation. This is because, generally, vulcanized rubber tends to exhibit better low heat generation properties as its hardness increases. Therefore, the low heat generation properties were compared after standardizing the hardness, which affects rigidity and abrasion resistance.

[0059] For each of the obtained rubber compositions, vulcanized rubber samples of a predetermined shape were prepared by vulcanization at 160°C for 30 minutes, and their hardness, low heat generation, and dispersibility were measured and evaluated. The results are shown in Table 1.

[0060] [Table 1]

[0061] Comparative Example 1-1 is a standard formulation using a combination of sulfenamide and guanidine as vulcanization accelerators. In Comparative Examples 1-2 and 1-3, in which the guanidine vulcanization accelerator was replaced with a thiram-based vulcanization accelerator other than the above-mentioned thiram disulfide (1), dispersibility was improved, but no improvement in low heat generation was observed. In Comparative Example 1-6, although the above-mentioned thiram disulfide (1) was included, the amount included was small and the low heat generation was poor. In Comparative Example 1-4, although the above-mentioned thiram disulfide (1) was included in the specified amount, the amount of silica included was small and the low heat generation was poor. In Comparative Example 1-5, although the above-mentioned thiram disulfide (1) was included in the specified amount, the low heat generation was poor because modified SSBR was not included.

[0062] In contrast, in Examples 1-1 to 1-6, which incorporated a specified amount of silica into modified SSBR and the above-mentioned thiuram disulfide (1), the dispersibility was greatly improved compared to Comparative Example 1-1, and an improvement in low heat generation was observed.

[0063] [Second Experimental Example] A rubber composition was prepared according to the formulation (parts by mass) shown in Table 2 below, with the rest being the same as in the first experimental example. The hardness, low heat generation, and dispersibility of the obtained rubber composition were measured and evaluated in the same manner as in the first experimental example. The results are shown in Table 2. In Table 2, Comparative Example 2-1 was used as the standard formulation, and the amount of vulcanization accelerator added was adjusted to achieve approximately the same hardness as the standard formulation.

[0064] [Table 2]

[0065] The second experimental example is one in which the type of modified SSBR, silica content, and type of silane coupling agent were changed compared to the first experimental example. In the second experimental example, as in the first experimental example, the rubber hardness was kept approximately the same, and the effect of the difference in vulcanization accelerators on low heat generation and dispersibility was investigated. In Examples 2-1 to 2-4, which incorporated the above-mentioned thiuram disulfide (1), dispersibility was greatly improved and an improvement in low heat generation was observed compared to Comparative Example 1-1.

[0066] Furthermore, the various numerical ranges described in this specification can be any combination of their upper and lower limits, and all such combinations are described herein as preferred numerical ranges. Also, the description of a numerical range as "X~Y" means X or greater and Y or less.

Claims

1. The rubber component includes modified solution polymerized styrene-butadiene rubber, silica, and a thiram-based vulcanization accelerator represented by the following general formula (1). 【Chemistry 1】 In formula (1), R １ , R ２ , R ３ and R ４ Each is independently a hydrocarbon group having 12 to 20 carbon atoms, which may optionally contain one or more heteroatoms, R １ and R ２ , and / or, R ３ and R ４ These may each form a heterocyclic group together with the nitrogen atom to which they are bonded. With respect to 100 parts by mass of the rubber component, the silica content is 80 to 140 parts by mass, and the thiram-based vulcanization accelerator content is 0.2 to 6 parts by mass. Rubber composition.

2. The rubber composition according to claim 1, which is a rubber composition for tires.

3. A tire comprising a rubber portion made from the rubber composition described in claim 1 or 2.

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