Rubber composition and surface-treated silica

Abstract

To provide a rubber composition comprising a filler surface-treated with a predetermined organosilicon compound and capable of achieving desired fuel efficient tire performance and wear resistance performance while maintaining the processability of the composition and the hardness and tensile properties of its cured product.SOLUTION: There is provided a rubber composition comprising a filler surface-treated with an organosilicon compound represented by formula (1). (R1 is an alkyl group having 1 to 10 carbon atoms or the like; R2 is an alkyl group having 1 to 10 carbon atoms or the like; R3 is H, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R4 is H or a hydrocarbon group having 1 to 20 carbon atoms which may contain a substituent other than an S-containing group and may contain a hetero atom other than S (provided that R4 may crosslink with one another to form a ring); Z is a divalent group having no polysulfide group, thioester group or mercapto group; n is an integer of 1 to 3.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a rubber composition and a surface-treated silica, and more specifically to a rubber composition containing a filler that has been surface-treated with a specific organosilicon compound, and to silica that has been surface-treated with a specific organosilicon compound. [Background technology]

[0002] Silica-filled tires have excellent performance in automotive applications, especially in terms of wear resistance, rolling resistance, and wet grip. These performance improvements are closely related to the improvement of fuel efficiency of tires, so silica-filled tires have been actively researched in the passenger tire industry, especially those using solution-polymerized styrene-butadiene rubber (S-SBR).

[0003] Although silica-filled rubber compositions reduce the rolling resistance of tires and improve wet grip performance, they have a high unvulcanized viscosity, require multi-stage kneading, and have problems with workability. Therefore, in rubber compositions in which inorganic fillers such as silica are simply blended, the filler is not sufficiently dispersed, resulting in problems such as a significant decrease in fracture strength and abrasion resistance. Therefore, in order to improve the dispersion of the inorganic filler in the rubber and to chemically bond the filler to the rubber matrix, a sulfur-containing organosilicon compound has been essential.

[0004] As sulfur-containing organosilicon compounds used as compounding agents for rubber, compounds containing an alkoxysilyl group and a polysulfide silyl group in the molecule, such as bis-triethoxysilylpropyl tetrasulfide and bis-triethoxysilylpropyl disulfide, are known to be effective (see Patent Documents 1 to 4).

[0005] In addition, high-load-bearing tires fitted to trucks, buses and the like are required to have high fracture resistance so that they can withstand use under harsh conditions, and natural rubber is used for these tires. However, even for such tires, there is an increasing demand for improved fuel economy and wear resistance (Patent Document 5). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2004-525230 [Patent Document 2] JP 2004-18511 A [Patent Document 3] JP 2002-145890 A [Patent Document 4] JP 2000-103795 A [Patent Document 5] JP 2019-131649 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber composition which contains a filler which has been surface-treated with a specified organosilicon compound and which is capable of achieving desired fuel-efficient tire performance and abrasion resistance while maintaining the processability of the composition and the hardness and tensile properties of the cured product thereof, as well as a tire formed from this rubber composition, and a surface-treated silica which is suitable as the filler. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems, and as a result have discovered that a tire obtained from a rubber composition containing a filler that has been surface-treated with a specific organosilicon compound having an aniline skeleton and a hydrolyzable silyl group can achieve desired fuel efficiency and wear resistance while maintaining hardness and tensile properties, thereby completing the present invention.

[0009] That is, the present invention provides 1. A rubber composition comprising a filler that has been surface-treated with an organosilicon compound represented by the following formula (1): [ka] (In the formula, R 1 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 3 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than a sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom (provided that adjacent R 4 may be crosslinked to form a ring; Z represents a divalent group that does not have a polysulfide group, a thioester group, or a mercapto group; and n represents an integer of 1 to 3. 2. The rubber composition according to claim 1, wherein the organosilicon compound is one or more selected from organosilicon compounds represented by the following formulas (2) to (4): [ka] (In the formula, R 1 , R 2 , R 3 , R 4 and n are as defined above, m is an integer of 1 to 12, and p is an integer of 1 to 12. 3. The rubber composition according to 1 or 2, which contains natural rubber; 4. A tire obtained by molding the rubber composition according to any one of 1 to 3. 5. BET specific surface area 50~500m 2 / g of silica, the surface of which is treated with an organosilicon compound represented by the following formula (1): [ka] (In the formula, R 1 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 3represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than a sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom (provided that adjacent R 4 may be crosslinked to form a ring; Z represents a divalent group that does not have a polysulfide group, a thioester group, or a mercapto group; and n represents an integer of 1 to 3. 6. The surface-treated silica according to 5, wherein the organosilicon compound is one or more selected from the organosilicon compounds represented by the following formulas (2) to (4): [ka] (In the formula, R 1 , R 2 , R 3 , R 4 and n are as defined above, m is an integer of 1 to 12, and p is an integer of 1 to 12. to provide. Effect of the Invention

[0010] The rubber composition of the present invention has excellent processability, and a tire formed using this rubber composition can satisfy the desired fuel-efficient tire properties and wear resistance while maintaining hardness and tensile properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be specifically described below. The rubber composition of the present invention is a rubber composition containing a filler (hereinafter sometimes referred to as a "surface-treated filler") that has been surface-treated with an organosilicon compound represented by the following formula (1).

[0012] [ka]

[0013] R 1each independently represents an alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, and more preferably 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 3 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms, preferably 6 to 8 carbon atoms; R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than a sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom (provided that adjacent R 4 They may be crosslinked to form a ring. Z represents a divalent group that does not have a polysulfide group, a thioester group or a mercapto group; n represents an integer of 1 to 3.

[0014] R 1 The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, and cyclohexyl groups. Specific examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a tolyl group. Among these, R 1 is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group.

[0015] R 2 The alkyl group having 1 to 10 carbon atoms and the aryl group having 6 to 10 carbon atoms are each R 1 Among these, a methyl group is more preferable.

[0016] R 3The alkyl group having 1 to 10 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, and cyclohexyl groups, and specific examples of the aryl group having 6 to 10 carbon atoms include phenyl and tolyl groups. 3 is preferably a hydrogen atom, a methyl group, an ethyl group, or a phenyl group.

[0017] R 4 Examples of the hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than the sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom include linear, branched and cyclic alkyl groups, aryl groups and aralkyl groups. Specifically, straight-chain, branched and cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, n-hexyl, cyclohexyl 3-hexyl, isohexyl, tert-hexyl, heptyl, isoheptyl, octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, cyclopentyl, cyclohexyl, cycloheptyl, methylcyclohexyl and tert-butylcyclohexyl; trifluoromethyl and trichloromethyl. haloalkyl groups such as tetrafluoroethyl and tetrachloroethyl; alkoxy groups such as methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, s-butyloxy, isobutyloxy, t-butyloxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy and n-decyloxy; cycloalkoxy groups such as cyclopropyloxy, cyclobutyloxy, cyclopentyloxy and cyclohexyloxy; aryl groups such as phenyl, naphthyl and anthracenyl; aryloxy groups such as phenyloxy, 1-naphthyloxy and 2-naphthyloxy; phenyl-C1-C 12 Alkyl, naphthyl-C1~C 10Alkyl and arylalkyl groups such as anthracenyl-C1-C6 alkyl; phenyl-C1-C 12 Alkoxy, naphthyl-C1~C 10 heterocyclic groups such as pyrrolyl, furanyl, furyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, triazinyl, pyrrolidyl, piperidyl, quinolyl, isoquinolyl; aryl or alkylamino groups such as phenylamino and methylamino; alkylsilyl groups such as trimethylsilyl; acyl groups such as acetyl, propionyl, butyryl, isobutyryl, pivaloyl, and benzoyl; acyloxy groups such as acetoxy, propionyloxy, butyryloxy, isobutyryloxy, pivaloyloxy, and benzoyloxy; carboxy groups; and cyano groups.

[0018] Among these, R 4 is preferably a hydrogen atom or an arylamino group, and all of R 4 is preferably a hydrogen atom or a combination of a hydrogen atom and a phenylamino group, and all of R 4 is a hydrogen atom or a combination of four hydrogen atoms and one phenylamino group is even more preferred.

[0019] Z is not particularly limited as long as it is a divalent group that does not have a polysulfide group, a thioester group, or a mercapto group, and examples thereof include an oxygen atom (-O-), an alkylene group having 1 to 20 carbon atoms which may contain a sulfur atom (-S-), -NHCO-, -CONH-, -COO-, -OCO-, and combinations thereof. Among these, -(CH2) m -(m represents an integer of 1 to 12, preferably 1 to 6), -(CH2) m -S-(CH2) p -(m and p each independently represent an integer of 1 to 12, preferably 1 to 6), -(CH2) m The --NHCO-- (wherein m has the same meaning as above) group is preferred.

[0020] Therefore, the organosilicon compound is preferably one represented by the following formulas (2) to (4).

[0021] [ka] (In the formula, R 1 , R 2 , R 3 , R 4 , n, m and p have the same meanings as above.)

[0022] Examples of the organosilicon compound represented by the above formula (2) include compounds represented by the following formula: In the following formula, Me represents a methyl group, and Et represents an ethyl group (the same applies hereinafter).

[0023] [ka]

[0024] [ka]

[0025] Examples of the organosilicon compound represented by the above formula (3) include compounds represented by the following formula:

[0026] [ka]

[0027] [ka]

[0028] Examples of the organosilicon compound represented by the above formula (4) include compounds represented by the following formula:

[0029] [ka]

[0030] [ka]

[0031] The organosilicon compounds may be used alone or in combination of two or more kinds.

[0032] Examples of the filler include fillers commonly used in the tire industry, such as silica, carbon black, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, clay, etc., which may be used alone or in combination of two or more. Among these, it is preferable to contain silica or carbon black, and it is more preferable to contain silica.

[0033] Examples of silica include silica prepared by a dry method (anhydrous silica) and silica prepared by a wet method (hydrated silica), which are commonly used in the tire industry. Among these, silica prepared by a wet method is preferred because it contains a large number of silanol groups. In particular, silica has a nitrogen adsorption specific surface area (N2SA) of 50m2 by the BET one-point method. 2 / g or more is preferable, and 100m 2 The upper limit of N2SA is not particularly limited, but from the viewpoint of ease of handling, it is preferably 500 m 2 / g or less is preferable, and 400m 2 / g or less is more preferable.

[0034] The content of the organosilicon compound contained in the filler surface-treated with the organosilicon compound represented by the above formula (1) is preferably 0.01 to 20 mass %, more preferably 0.1 to 10 mass %, based on the total mass of the surface-treated filler. The surface treatment method is not particularly limited, but may be a general powder surface treatment method such as a dry method or a wet method.

[0035] The rubber composition of the present invention preferably contains a diene rubber, and as the diene rubber, any rubber that has been generally used in various conventional rubber compositions can be used. Specific examples include various isoprene rubbers (IR) such as natural rubber, various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), diene rubbers such as acrylonitrile-butadiene copolymer rubbers (NBR), and the like. These may be used alone or in combination of two or more.

[0036] In particular, it is preferable that the diene rubber component contains natural rubber. Since sufficient fracture resistance can be obtained even when used as a tire for a heavy-load vehicle, the content of natural rubber in the diene rubber component is preferably 50% by mass or more, and more preferably 70 to 100% by mass. As the natural rubber, those commonly used in the tire industry such as RSS#3, SIR20, TSR20, etc. Also usable are modified natural rubbers such as epoxidized natural rubber, hydrogenated natural rubber, grafted natural rubber, and deproteinized natural rubber.

[0037] Furthermore, the rubber composition of the present invention preferably contains an organosilicon compound having at least one selected from a polysulfide group, a thioester group, and a mercapto group, and an alkoxysilyl group.The organosilicon compound is not particularly limited as long as it is a compound having the above-mentioned functional group, and for example, any conventionally known silane coupling agent that is blended in a rubber composition for use in tires and the like can be used.

[0038] Specific examples of silane coupling agents include polysulfide-based organosilicon compounds such as bis-(3-bistriethoxysilylpropyl)-tetrasulfide and bis-(3-bistriethoxysilylpropyl)-disulfide; mercapto-based organosilicon compounds such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; and thioester-type organosilicon compounds such as 3-octanoylthiopropyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. Also usable are the reaction products of the above-mentioned organosilicon compounds having sulfur atoms with alcohols having polyether groups, the hydrolysis condensation products of these organosilicon compounds, and the co-hydrolysis condensation products of these organosilicon compounds with other organosilicon compounds having alkoxysilyl groups.The organosilicon compounds having alkoxysilyl groups and one or more selected from polysulfide groups, thioester groups, and mercapto groups may be used alone or in combination of two or more.

[0039] In the composition of the present invention, the amount of the organosilicon compound having an alkoxysilyl group and one or more groups selected from a polysulfide group, a thioester group, and a mercapto group is not particularly limited, but is preferably 3 to 30 mass % and more preferably 5 to 20 mass % based on the silica blended in terms of mass ratio.

[0040] The rubber composition of the present invention may further contain various additives that are generally used in tires and other rubbers, such as fillers, vulcanizing agents, crosslinking agents, vulcanization accelerators, crosslinking accelerators, various oils, antioxidants, plasticizers, etc. The amounts of these additives may be conventional amounts, as long as they do not go against the object of the present invention.

[0041] Examples of the filler include fillers other than the filler surface-treated with the organosilicon compound represented by the above formula (1), which are commonly used in the tire industry, such as silica, carbon black, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, talc, and clay, and these may be used alone or in combination of two or more. Among these, it is preferable to contain silica and carbon black, and it is more preferable to contain only silica and carbon black.

[0042] Examples of carbon black include those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF. Examples of silica include silica prepared by a dry method (anhydrous silica) and silica prepared by a wet method (hydrated silica), which are commonly used in the tire industry. Among these, silica prepared by a wet method is preferred because it contains a large number of silanol groups. In particular, silica has a nitrogen adsorption specific surface area (N2SA) of 70m 2 / g or more is preferable, and 100m 2 The upper limit of N2SA is not particularly limited, but from the viewpoint of ease of handling, it is preferably 500 m 2 / g or less is preferable, and 400m 2 / g or less is more preferable.

[0043] The amount of filler in the rubber composition of the present invention is preferably 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and even more preferably 20 to 100 parts by mass, per 100 parts by mass of the rubber component, from the viewpoints of dispersibility, fuel economy, molding processability, etc.

[0044] [Rubber products (tires)] The rubber composition of the present invention can be used for producing rubber products such as tires by preparing a composition from the above-mentioned components and other components by a general method, and vulcanizing or crosslinking the composition. In particular, when producing tires, it is preferable that the rubber composition of the present invention is used in the tread. A tire obtained by using the rubber composition of the present invention has reduced rolling resistance and improved wear resistance, and therefore can achieve the desired low fuel consumption. The structure of the tire may be a conventionally known structure, and the manufacturing method may be a conventionally known manufacturing method. In the case of a gas-filled tire, the gas to be filled in the tire may be normal air, air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0045] The present invention will be described in more detail below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples. In the following formulae, Ph represents a phenyl group.

[0046] [Synthesis Example 1-1] 372.4g (4.0mol) of aniline (Tokyo Chemical Industry Co., Ltd.) was placed in a 1L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, and then 240.8g (1.0mol) of chloropropyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-703) was dropped at 120°C, and the mixture was aged for 4 hours at 120°C. Then, a filtration process and distillation purification were performed to obtain an organosilicon compound (A-1) represented by the following formula. (EtO)3Si-C3H6-NHPh···(A-1)

[0047] [Synthesis Example 1-2] In a 1L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 428.8g (4.0mol) of N-methylaniline (Tokyo Chemical Industry Co., Ltd.) was placed, and then 198.7g (1.0mol) of chloropropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-703) was dropped at 120°C, and the mixture was aged for 4 hours at 120°C. After that, a filtration process and distillation purification were performed to obtain an organosilicon compound (A-2) represented by the following formula. (MeO)3Si-C3H6-NMePh...(A-2)

[0048] [Synthesis Example 1-3] In a 1L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 133.2g (1.0mol) of N-allylaniline (Tokyo Chemical Industry Co., Ltd.), 196.3g (1.0mol) of 3-mercaptopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-803) and 300g of toluene were placed, and then 5.0g of Perbutyl-O (NOF Corp.) was added dropwise at 100°C and the mixture was aged at 100°C for 4 hours. The solvent was then distilled off to obtain the organosilicon compound (A-3) represented by the following formula. (MeO)3Si-C3H6-S-C3H6-NHPh...(A-3)

[0049] [Synthesis Example 1-4] 93.2g (1.0mol) of aniline (Tokyo Chemical Industry Co., Ltd.) was placed in a 1L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, and then 247.4g (1.0mol) of 3-isocyanatepropyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-9007N) was added dropwise at 80°C. The mixture was then aged at 80°C for 4 hours to obtain an organosilicon compound (A-4) represented by the following formula. (EtO)3Si-C3H6-NHCONHPh...(A-4)

[0050] [2] Synthesis of surface treatment filler [Example 1-1] Silica [BET specific surface area: 160 m] was added to a 5 L Henschel mixer (manufactured by Nippon Coke Engineering Co., Ltd.; the same applies below). 2 20 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM-573, Shin-Etsu Chemical Co., Ltd.; the same applies below) was sprayed onto the mixture and stirred at 25°C for 10 minutes. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80°C for 24 hours to obtain surface-treated silica A.

[0051] [Example 1-2] 1,000 g of silica was placed in a 5 L Henschel mixer, 20 g of the organosilicon compound (A-1) obtained in Synthesis Example 1-1 above was sprayed thereon, and the mixture was stirred for 10 minutes at 25° C. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80° C. for 24 hours to obtain surface-treated silica B.

[0052] [Examples 1-3] 1,000 g of silica was placed in a 5 L Henschel mixer, 20 g of the organosilicon compound (A-2) obtained in Synthesis Example 1-2 above was sprayed thereto, and the mixture was stirred for 10 minutes at 25° C. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80° C. for 24 hours to obtain surface-treated silica C.

[0053] [Examples 1-4] 1,000 g of silica was placed in a 5 L Henschel mixer, 20 g of the organosilicon compound (A-3) obtained in Synthesis Example 1-3 above was sprayed thereon, and the mixture was stirred for 10 minutes at 25° C. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80° C. for 24 hours to obtain surface-treated silica D.

[0054] [Examples 1-5] 1,000 g of silica was placed in a 5 L Henschel mixer, 20 g of the organosilicon compound (A-4) obtained in Synthesis Example 1-4 above was sprayed thereon, and the mixture was stirred for 10 minutes at 25° C. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80° C. for 24 hours to obtain surface-treated silica E.

[0055] [Synthesis Example 2-1] 1,000 g of carbon black [Seast 9H, manufactured by Tokai Carbon Co., Ltd.] was placed in a 5 L Henschel mixer, 20 g of N-phenyl-3-aminopropyltrimethoxysilane was sprayed thereon, and the mixture was stirred for 10 minutes at 25° C. The mixture was then removed from the Henschel mixer and dried in a thermostatic chamber at 80° C. for 24 hours to obtain surface-treated carbon black A.

[0056] [3] Manufacturing of rubber composition [Examples 2-1 to 2-6, Comparative Example 2-1] Using a 4 L internal mixer (MIXTRON, manufactured by Kobe Steel, Ltd., the same applies below), natural rubber was kneaded for 60 seconds in the compounding amounts (parts by mass) shown in Table 1. Next, carbon black, silica, sulfide silane, stearic acid, antioxidant, resin, and wax shown in Table 1 were added, the internal temperature was raised to 150°C, and the mixture was discharged. Thereafter, the mixture was stretched using rolls. The obtained rubber was again kneaded using an internal mixer until the internal temperature reached 145°C, discharged, and then stretched using rolls. Zinc oxide, vulcanization accelerator, and sulfur shown in Table 1 were added thereto and kneaded to obtain a rubber composition.

[0057] Natural rubber: RSS#3 Silica: Nipsil AQ (manufactured by Tosoh Silica Co., Ltd.) Carbon black: Seast 9H (manufactured by Tokai Carbon Co., Ltd.) Sulfide silane: KBE-846 (Shin-Etsu Chemical Co., Ltd.) Stearic acid: Industrial stearic acid (Kao Corporation) Anti-aging agent: Nocrac 6C (Ouchi Shinko Chemical Industry Co., Ltd.) Resin: T-REZ RA-100 (manufactured by ENEOS Corporation) Wax: Ozoace 0355 (manufactured by Nippon Seiro Co., Ltd.) Zinc oxide: Zinc oxide No. 3 (manufactured by Mitsui Mining & Smelting Co., Ltd.) Vulcanization accelerator (a): Noccela DM-P (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Vulcanization accelerator (b): Noccela CZ-G (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Sulfur: 5% oil-treated sulfur (Hosoi Chemical Industry Co., Ltd.)

[0058] The unvulcanized and vulcanized physical properties of the rubber compositions obtained in Examples 2-1 to 2-6 and Comparative Example 2-1 were measured by the following methods. The results are also shown in Table 1. Regarding the vulcanized physical properties, the obtained rubber compositions were press molded (145°C, 30 minutes) to produce vulcanized rubber sheets (thickness 2 mm).

[0059] [Unvulcanized physical properties] (1) Mooney Viscosity According to JIS K 6300-1:2013, the measurement was performed with 1 minute of preheating and 4 minutes of measurement at a temperature of 130°C, and expressed as an index with Comparative Example 2-1 being 100. The smaller the index value, the lower the Mooney viscosity and the better the processability. [Vulcanization properties] (2)Hardness The durometer (type A) hardness was measured in accordance with JIS K 6253-3:2012, and expressed as an index with the value of Comparative Example 2-1 set to 100. (3) Tensile properties A JIS No. 3 dumbbell-shaped test piece was punched out and a tensile test was performed at a tensile speed of 500 mm / min in accordance with JIS K6251. The 300% modulus (M 300 ) [MPa] was measured at room temperature. The results were expressed as an index, with Comparative Example 2-1 being set at 100. A larger index value indicates a higher modulus and more excellent tensile properties. (4) Dynamic viscoelasticity (strain dispersion) Using a viscoelasticity measuring device (manufactured by Metravib), the storage modulus E'(0.5%) at 0.5% strain and the storage modulus E'(3.0%) at 3.0% strain were measured under conditions of 25°C and 55Hz, and the value of [E'(0.5%)-E'(3.0%)] was calculated. The test piece was a sheet with a thickness of 0.2 cm and a width of 0.5 cm, the clamp distance was 2 cm, and the initial load was 1N. The value of [E'(0.5%)-E'(3.0%)] is expressed as an index with Comparative Example 2-1 being 100, and the smaller the index value, the better the dispersibility of the silica. (5) Dynamic viscoelasticity (temperature dispersion) A viscoelasticity measuring device (manufactured by Metravib) was used to measure under conditions of a tensile dynamic strain of 1% and a frequency of 55 Hz. The test specimen was a sheet having a thickness of 0.2 cm and a width of 0.5 cm, the clamp distance used was 2 cm, and the initial load was 1 N. The value of tan δ (60°C) was expressed as an index, with the value of Comparative Example 2-1 being 100. The smaller the index value of tan δ (60°C), the better the rolling resistance. (6) Abrasion resistance Using an FPS tester (manufactured by Ueshima Seisakusho Co., Ltd.), the test was carried out under the conditions of a sample speed of 200 m / min, a load of 20 N, a road surface temperature of 30°C, and a slip rate of 5% and a slip rate of 20%. The results obtained were expressed as an index, with Comparative Example 2-1 being set at 100. A larger index value indicates less wear and better wear resistance.

[0060] [Table 1]

[0061] As shown in Table 1, the vulcanizates of the rubber compositions of Examples 2-1 to 2-6 have lower dynamic viscoelasticity, i.e., smaller hysteresis loss and lower heat build-up, and are superior in abrasion resistance, while maintaining hardness and tensile properties, compared to the vulcanizate of the rubber composition of Comparative Example 2-1.

Claims

1. A rubber composition comprising a filler that has been surface-treated with an organosilicon compound represented by the following formula (3): 【Chemistry 1】 (In the formula, R 1 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 3 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than a sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom (provided that adjacent R 4 may be crosslinked to form a ring. n represents an integer of 1 to 3, m represents an integer of 1 to 12, and p represents an integer of 1 to 12.

2. The rubber composition according to claim 1, wherein m and p each independently represent an integer of 1 to 6.

3. The rubber composition according to claim 1 or 2, which contains natural rubber.

4. A tire produced by molding the rubber composition according to any one of claims 1 to 3.

5. BET specific surface area 50-500m 2 / g, the surface of which is treated with an organosilicon compound represented by the following formula (3): 【Chemistry 2】 (In the formula, R 1 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 2 each independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms; R 3 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent other than a sulfur atom-containing group and which may contain a heteroatom other than a sulfur atom (provided that adjacent R 4 may be crosslinked to form a ring. n represents an integer of 1 to 3, m represents an integer of 1 to 12, and p represents an integer of 1 to 12.

6. 6. The surface-treated silica according to claim 5, wherein m and p each independently represent an integer of 1 to 6.

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