Rubber composition and tire

Abstract

To provide a rubber composition for a tread which is excellent in wet grip performance and wear resistance performance, and to provide a tire.SOLUTION: The rubber composition contains a rubber component, a surfactant, silica, and at least one plasticizer component selected from the group consisting of liquid plasticizers and resins. The content (A) of the silica and the content (B) of the plasticizer component based on 100 pts.mass of the rubber component satisfy the following formulae (1) and (2): 70≤A≤150 (1); and B≤A≤B+100 (2).SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] From the viewpoints of safety and the environment, tire treads are required to have performance such as wet grip performance when traveling on wet roads and wear resistance, and performance improvements have been made, for example, by devising the rubber components, fillers, etc. used in the tread.

[0003] For example, Patent Document 1 discloses a technique of blending a specific modified diene rubber with a specific silica to impart good tire properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 125614 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to solve the above problems and to provide a rubber composition for a tread and a tire which are excellent in wet grip performance and abrasion resistance. [Means for solving the problem]

[0006] The present invention relates to a rubber composition comprising a rubber component, a surfactant, silica, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, wherein the content (A) of the silica and the content (B) of the plasticizer component per 100 parts by mass of the rubber component satisfy the following formulas (1) and (2): 70≦A≦150 (1) B≦A≦B+100 (2)

[0007] The surfactant is preferably contained in an amount of 1 to 20 parts by mass based on 100 parts by mass of the rubber component.

[0008] The surfactant is preferably contained in an amount of 5 to 20 parts by mass based on 100 parts by mass of the rubber component.

[0009] The surfactant is preferably a nonionic surfactant. The silica has a nitrogen adsorption specific surface area of ​​150 m 2 / g or more is preferable.

[0010] The resin is preferably contained in an amount of 5 to 30 parts by mass relative to the rubber component. The plasticizer component is preferably contained in an amount of 80 to 200 parts by mass relative to the rubber component.

[0011] It is preferable that the content of the styrene butadiene rubber is 40 to 60% by mass, the content of the butadiene rubber is 5 to 30% by mass, and the content of the isoprene rubber is 10 to 40% by mass, based on 100% by mass of the rubber component.

[0012] It is preferable to contain a mercapto coupling agent.

[0013] The present invention also relates to a tire having a tread made from the rubber composition. [Effects of the Invention]

[0014] According to the present invention, a rubber composition includes a rubber component, a surfactant, silica, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, and the content (A) of the silica and the content (B) of the plasticizer component per 100 parts by mass of the rubber component satisfy the formulas (1) and (2). Therefore, a rubber composition for tread and a tire having excellent wet grip performance and wear resistance can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0015] The rubber composition of the present invention includes a rubber component, a surfactant, silica, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, and the content (A) of the silica and the content (B) of the plasticizer component per 100 parts by mass of the rubber component satisfy the above formulas (1) and (2), thereby significantly improving wet grip performance and abrasion resistance.

[0016] The reason why such an effect is obtained is not clear, but it is presumed to be due to the following mechanism. Wet grip performance is improved by high silica loading and by incorporating plasticizer components such as resin (resin component) and liquid plasticizer. Therefore, it is believed that dispersing silica in both the plasticizer component phase and the rubber phase is particularly important for improving wet grip performance. Therefore, by simultaneously loading silica to a high level to satisfy formula (1) and adjusting the silica content to be equal to or greater than the content of the plasticizer component (resin and liquid plasticizer) but less than the total amount of the rubber component and plasticizer component to satisfy formula (2), it is believed that silica can be well dispersed in these phases. Furthermore, adding a surfactant to such a formulation hydrophobizes the silica surface, enabling the silica to be better dispersed in the rubber phase and the plasticizer component phase, further improving wet grip performance. In addition, high silica loading and uniform silica dispersion are believed to significantly improve abrasion resistance. Therefore, it is predicted that wet grip performance and abrasion resistance will be significantly improved.

[0017] In the rubber composition, the content of silica (A (parts by mass)) relative to 100 parts by mass of the rubber component satisfies the following formula (1), and the content of at least one plasticizer component selected from the group consisting of liquid plasticizers and resins (B (parts by mass): total content of liquid plasticizer and resin) relative to 100 parts by mass of the rubber component satisfies the following formula (2). 70≦A≦150 (1) B≦A≦B+100 (2)

[0018] In formula (1), the lower limit of A (the lower limit of the silica content) is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 100 parts by mass or more. The upper limit of A (the upper limit of the silica content) is preferably 150 parts by mass or less, more preferably 145 parts by mass or less, and even more preferably 140 parts by mass or less. By making A equal to or greater than the lower limit, good wet grip performance and abrasion resistance tend to be obtained, and by making it equal to or less than the upper limit, good dispersibility tends to be obtained.

[0019] Formula (2) is preferably B+15≦A≦B+80, more preferably B+30≦A≦B+60. By keeping it within the above range, the dispersibility of silica is improved, and good wet grip performance and abrasion resistance tend to be obtained.

[0020] The formulas (1) and (2) can be satisfied by appropriately adjusting the silica content, the liquid plasticizer content, and the resin content.

[0021] Examples of the rubber component include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Examples of the isoprene rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Among these, from the viewpoints of wet grip performance and abrasion resistance, SBR, BR, and isoprene rubber are preferred, and SBR is more preferred. The rubber component may be used alone or in combination of two or more.

[0022] The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used.

[0023] The content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. By setting the content at or above the lower limit, good wet grip performance and abrasion resistance tend to be obtained. The upper limit of the SBR content is not particularly limited and may be 100% by mass. Alternatively, the upper limit may be 80% by mass or less, or 60% by mass or less.

[0024] The styrene content of the SBR is preferably 20% by mass or more, more preferably 22% by mass or more. By making it equal to or greater than the lower limit, good wet grip performance tends to be obtained. Furthermore, the styrene content is preferably 50% by mass or less, more preferably 47% by mass or less. By making it equal to or less than the upper limit, not only good wear resistance is obtained, but also the temperature dependency of grip performance is reduced, and stable wet grip performance during driving tends to be obtained. In the present invention, the styrene content of SBR is H 1 - Calculated by NMR measurement.

[0025] The vinyl content of the SBR (the vinyl content in the butadiene component of the SBR) is preferably 15% by mass or more, more preferably 35% by mass or more. By making it equal to or greater than the lower limit, good wet grip performance tends to be obtained. The vinyl content is preferably 65% ​​by mass or less, more preferably 60% by mass or less. By making it equal to or less than the upper limit, excellent wet grip performance tends to be obtained over a wide temperature range. The vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0026] In addition to unmodified SBR, modified SBR can also be used as SBR. The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples include terminal-modified SBR (terminal-modified SBR having the functional group at the terminal) in which at least one terminal of SBR has been modified with a compound (modifier) ​​having the functional group, main-chain-modified SBR having the functional group at the main chain, main-chain terminal-modified SBR having the functional group at the main chain and the terminal (for example, main-chain terminal-modified SBR having the functional group at the main chain and at least one terminal modified with the modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having hydroxyl groups or epoxy groups introduced therein.

[0027] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0028] As the modified SBR, SBR modified with a compound (modifier) ​​represented by the following formula is particularly preferred. [ka] (In the formula, R 1 , R 2 and R 3 R may be the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R5 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0029] As the modified SBR modified with the compound (modifier) ​​represented by the above formula, SBR in which the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) has been modified with the compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A) is preferably used.

[0030] R 1 , R 2 and R 3 R is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, R 4 and R 5 When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

[0031] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. Among these, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyltriethoxysilane, and 3-diethylaminopropyltrimethoxysilane are preferred. These may be used alone or in combination of two or more.

[0032] The modified SBR may be modified with the following compounds (modifiers): Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups, such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; and 4,4'- Epoxy group-containing tertiary amines such as diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylamino compounds such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane;

[0033] Amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;

[0034] sulfide group-containing silane compounds such as (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide;

[0035] N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane; (thio)benzophenone compounds having amino groups and / or substituted amino groups such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N benzaldehyde compounds having an amino group and / or a substituted amino group, such as N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone; N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; and

[0036] Examples of suitable SBR include N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Among these, modified SBR modified with alkoxysilane is preferred. The modification with the above compound (modifying agent) can be carried out by a known method.

[0037] As the SBR, oil-extended SBR can also be suitably used. Oil-extended SBR is SBR that has been extended with an extender oil. By incorporating oil-extended SBR that has been previously extended with an extender oil, the dispersibility of silica can be improved.

[0038] Examples of extender oils used to extend SBR include naphthenic, paraffinic, and aromatic oil-extending oils. Examples of methods for oil extension include adding an extender oil after polymerization is complete, and then removing the solvent and drying by a conventionally known method. The amount of extender oil used is preferably 5 to 100 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of SBR.

[0039] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0040] The BR is not particularly limited, and examples thereof include high-cis content BR, BR containing syndiotactic polybutadiene crystals, and rare-earth BR. Commercially available products include those from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation. The BR may be either unmodified or modified, and examples of modified BR include modified BRs having the aforementioned functional groups introduced therein. These may be used alone or in combination of two or more. Of these, high-cis content BR is preferred.

[0041] From the viewpoint of abrasion resistance and the like, the cis content (cis-1,4-bond content) of the high cis content BR is preferably 80 mass % or more, more preferably 90 mass % or more, and even more preferably 95 mass % or more.

[0042] The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of abrasion resistance. The upper limit of the content is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of wet grip performance.

[0043] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, and TSR20, which are commonly used in the tire industry. Examples of IR are not particularly limited, and examples of IR include IR2200, which are commonly used in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0044] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of abrasion resistance. The upper limit of the content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of wet grip performance.

[0045] The rubber composition includes a surfactant. The functional groups in the hydrophilic portion of the surfactant bond or interact with the hydroxyl groups on the silica surface, rendering the silica surface hydrophobic. Furthermore, the hydrophobic portion of the surfactant bonded or interacting with the silica allows the silica to dissolve in the rubber phase and the plasticizer component phase, which is thought to facilitate the breakdown of silica aggregates in the early stages of kneading, resulting in uniform dispersion of the silica. As a result, for example, the polymer phase and silica are more likely to react via the silane coupling agent, resulting in uniform bonding between the polymer phase, silane coupling agent, and silica. This uniform bonding is thought to increase the rigidity of the rubber and improve wear resistance.

[0046] On the other hand, although adding surfactants increases the drainage during driving due to the high rigidity, it also reduces the ability of the tire to follow the road surface when in contact with the ground, which tends to worsen wet grip performance. In this regard, it is believed that adding an appropriate amount of plasticizer component can reduce the hardness of the rubber and increase its ability to follow the road surface, thereby improving wet grip performance while maintaining wear resistance. Therefore, it is believed that wet grip performance and wear resistance will be significantly improved.

[0047] Surfactants include compounds with both hydrophobic and hydrophilic moieties, which improve silica dispersion and abrasion resistance. Furthermore, increasing the amount of fixed polymer terminal components in the rubber component increases the momentum of the rubber in response to road surface stimuli, increasing hysteresis loss and improving grip performance.

[0048] The content of the surfactant is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, and particularly preferably 7 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is 20 parts by mass or less, preferably 19 parts by mass or less, and more preferably 18 parts by mass or less. By keeping the content within the above range, good dispersibility can be obtained, and excellent wet grip performance and abrasion resistance tend to be obtained.

[0049] In surfactants (compounds having a hydrophobic portion and a hydrophilic portion), the hydrophobic portion may, for example, contain an alkyl group having 3 to 20 carbon atoms or a fluorinated alkyl group having 3 to 20 carbon atoms. Of these, an alkyl group having no fluorine atom is preferred.

[0050] Examples of alkyl groups having 3 to 20 carbon atoms include propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, eicosyl, etc. Among these, it is preferable to have a long-chain alkyl group, and specifically, an alkyl group having 5 to 20 carbon atoms is more preferable, and an alkyl group having 6 to 20 carbon atoms is even more preferable.

[0051] Examples of fluorinated alkyl groups having 3 to 20 carbon atoms include fluoropropyl, perfluorobutyl, perfluorohexyl, perfluorooctyl, perfluorodecyl, etc. Among these, it is preferable to have a fluoroalkyl group having a long carbon chain, and specifically, a fluorinated alkyl group having 4 to 20 carbon atoms is preferred, a fluorinated alkyl group having 5 to 20 carbon atoms is more preferred, and a fluorinated alkyl group having 6 to 20 carbon atoms is even more preferred.

[0052] Examples of the hydrophilic group that constitutes the hydrophilic portion include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, an alkyleneoxy group, an amino group, and a quaternary amino group.

[0053] Usable surfactants include known cationic surfactants, anionic surfactants, nonionic surfactants, etc. Among these, nonionic surfactants are preferred from the viewpoint of the above-mentioned effects.

[0054] Examples of nonionic surfactants include ester-type, ether-type, ester ether-type, alkanolamide-type, alkylglycoxide-type, higher alcohol-type, and poloxamer-type surfactants.

[0055] Examples of ester-type nonionic surfactants include glycerol laurate, glycerol monostearate, sorbitan fatty acid esters (sorbitan monofatty acid esters such as sorbitan monopalmitate, sorbitan monostearate, sorbitan monolaurate, and sorbitan monooleate, and sorbitan difatty acid esters such as sorbitan dipalmitate and sorbitan distearate), and sucrose fatty acid esters. Examples of ether-type nonionic surfactants include polyoxyethylene alkyl ethers (polyoxyethylene tridecyl ether, etc.), pentaethylene glycol monododecyl ether, octaethylene glycol monododecyl ether, polyoxyethylene alkylphenyl ether, octylphenol ethoxylate, nonylphenol ethoxylate, and polyoxyethylene polyoxypropylene glycol. Examples of ester-ether-type nonionic surfactants include polyoxyethylene sorbitan fatty acid esters (polyoxyethylene sorbitan monolaurate, etc.), polyoxyethylene hexitane fatty acid esters, and sorbitan fatty acid ester polyethylene glycol. Examples of alkanolamide surfactants include lauric acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, and cocamide DEA. Examples of alkylglycoxide surfactants include octyl glucoside, decyl glucoside, and lauryl glucoside. Examples of higher alcohol surfactants include cetanol, stearyl alcohol, and oleyl alcohol. Examples of poloxamer surfactants include poloxamer dimethacrylate. Among these, ester-type nonionic surfactants are preferred from the viewpoint of silica dispersibility.

[0056] Examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups.

[0057] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 80 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 150m 2 / g or more. By making it equal to or more than the lower limit, good abrasion resistance tends to be obtained. In addition, the N2SA of silica is preferably 300m 2 / g or less, more preferably 270m 2 / g or less, more preferably 250m 2 By setting the content to the upper limit or less, good dispersibility tends to be obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0058] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0059] When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent. The content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of silica. If the content is above the lower limit, good wet grip performance, abrasion resistance, etc. tend to be obtained. Furthermore, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. If the content is below the upper limit, effects commensurate with the blending amount tend to be obtained.

[0060] The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocalcium nitrate, Examples include sulfide-based compounds such as bamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry Co., Ltd., AZMAX Corporation, and Dow Corning Toray Co., Ltd. Among these, mercapto-based silane coupling agents are preferred because they provide good wet grip performance. These may be used alone or in combination of two or more.

[0061] Examples of mercapto-based silane coupling agents include silane coupling agents having a mercapto group, silane coupling agents in which the mercapto group is protected, etc. These may be used alone or in combination of two or more.

[0062] Suitable mercapto-based silane coupling agents include (i) a silane coupling agent represented by the following formula (2-1), and (ii) a silane coupling agent containing a bonding unit A represented by the following formula (2-2) and a bonding unit B represented by the following formula (2-3). [ka] (In formula (2-1), R 101 -Cl, -Br, -OR 106 , -O(O=)CR 106 , -ON=CR 106 R 107 , -ON=CR 106 R 107 , -NR 106 R 107 and-(OSiR 106 R 107 ) h (OSiR 106 R 107 R 108 a monovalent group (R 106 , R 107 and R 108 may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 102 is R 101 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 103 is -[O(R 109 O) j ]-group(R 109 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 104 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 105 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and xa, ya, and za are numbers that satisfy the relationship: xa+ya+2za=3, 0≦xa≦3, 0≦ya≦2, 0≦za≦1. [ka] [ka] (In formulas (2-2) and (2-3), xb is an integer of 0 or more, and yb is an integer of 1 or more. R 201 R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 202 represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 201 and R 202 may form a ring structure with

[0063] R in the above formula (2-1) 102 , R 105 , R 106 , R 107 and R 108 Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, and a naphthylmethyl group. R in the above formula (2-1) 109 Examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of the branched alkylene group include an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

[0064] Specific examples of the silane coupling agent represented by the above formula (2-1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. Of these, 3-octanoylthiopropyltriethoxysilane (NXT manufactured by Momentive Corp.) is particularly preferred. The above silane coupling agents may be used alone or in combination of two or more kinds.

[0065] Silane coupling agents containing the bonding unit A represented by the above formula (2-2) and the bonding unit B represented by the above formula (2-3) exhibit less increase in viscosity during processing than polysulfide silanes such as bis-(3-triethoxysilylpropyl)tetrasulfide. This is thought to be because the sulfide portion of bonding unit A is a CSC bond, which is more thermally stable than tetrasulfides and disulfides, resulting in less increase in Mooney viscosity.

[0066] In addition, the scorch time is reduced compared to mercaptosilanes such as 3-mercaptopropyltrimethoxysilane. This is because the bond unit A has the structure of mercaptosilane, but the -CH of the bond unit A 15 This is thought to be because the -SH group of the bonding unit B is covered by this moiety, making it less likely to react with the polymer and less likely to cause scorch.

[0067] In the silane coupling agent of the above structure, the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less.In addition, from the viewpoint of reactivity with silica, the content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less.In addition, the total content of the bond units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%. The content of the bonding units A and B includes the case where the bonding units A and B are located at the terminals of the silane coupling agent. When the bonding units A and B are located at the terminals of the silane coupling agent, the form of the bonding units A and B is not particularly limited, as long as they form units corresponding to the formulas (2-2) and (2-3) representing the bonding units A and B.

[0068] R 201 Examples of the halogen include chlorine, bromine, and fluorine.

[0069] R 201 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, etc. The number of carbon atoms in the alkyl group is preferably 1 to 12.

[0070] R 201 Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group, etc. The number of carbon atoms in the alkenyl group is preferably 2 to 12.

[0071] R 201Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group, an octynyl group, a nonynyl group, a decynyl group, an undecynyl group, a dodecynyl group, etc. The number of carbon atoms in the alkynyl group is preferably 2 to 12.

[0072] R 202 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group, etc. The number of carbon atoms of the alkylene group is preferably 1 to 12.

[0073] R 202 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, a 1-octenylene group, etc. The number of carbon atoms in the alkenylene group is preferably 2 to 12.

[0074] R 202 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octynylene group, a nonynylene group, a decynylene group, an undecynylene group, a dodecynylene group, etc. The number of carbon atoms in the alkynylene group is preferably 2 to 12.

[0075] In a silane coupling agent containing a bonding unit A represented by formula (2-2) and a bonding unit B represented by formula (2-3), the total number of repetitions (xb) of the bonding unit A and the number of repetitions (yb) of the bonding unit B (xb+yb) is preferably in the range of 3 to 300. Within this range, the mercaptosilane of the bonding unit B can be bonded to the -CH of the bonding unit A. 15Since the surface is covered with the silica, it is possible to prevent the scorch time from becoming shorter and to ensure good reactivity with the silica and rubber components.

[0076] Examples of silane coupling agents containing a bonding unit A represented by formula (2-2) and a bonding unit B represented by formula (2-3) include NXT-Z30, NXT-Z45, and NXT-Z60 manufactured by Momentive Corp. These may be used alone or in combination of two or more.

[0077] As the mercapto-based silane coupling agent, (iii) a silane coupling agent represented by the following formula (2-4) can also be suitably used.

[0078] [ka]

[0079] (In formula (2-4), R 6 ~R 8 represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R 10 -O) z -R 11 (z R 10 represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. 10 may be the same or different. 11 represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. z represents an integer of 1 to 30. R represents a group represented by 6 ~R 8 may be the same or different. 9 represents a branched or unbranched alkylene group having 1 to 6 carbon atoms.

[0080] R 6 ~R 8represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R 10 -O) z -R 11 R represents a group represented by the formula: 6 ~R 8 has at least one -O-(R 10 -O) z -R 11 and two of the groups are preferably -O-(R 10 -O) z -R 11 and one of the groups is a branched or unbranched alkoxy group having 1 to 12 carbon atoms.

[0081] R 6 ~R 8 Examples of the branched or unbranched alkyl group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, and a nonyl group.

[0082] R 6 ~R 8 Examples of the branched or unbranched alkoxy group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, a 2-ethylhexyloxy group, an octyloxy group, and a nonyloxy group.

[0083] R 6 ~R 8 -O-(R 10 -O) z -R 11 In R 10represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms). Examples of the hydrocarbon group include a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and an arylene group having 6 to 30 carbon atoms. Of these, a branched or unbranched alkylene group having 1 to 30 carbon atoms is preferred.

[0084] R 10 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) include a methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, and octadecylene group.

[0085] R 10 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) include a vinylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, and a 1-octenylene group.

[0086] R 10 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octynylene group, a nonynylene group, a decynylene group, an undecynylene group, and a dodecynylene group.

[0087] R 10Examples of the arylene group having 6 to 30 carbon atoms (preferably 6 to 15 carbon atoms) include a phenylene group, a tolylene group, a xylylene group, and a naphthylene group.

[0088] z represents an integer of 1 to 30 (preferably 2 to 20, more preferably 3 to 7, and even more preferably 5 or 6).

[0089] R 11 represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Of these, a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferred.

[0090] R 11 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and an octadecyl group.

[0091] R 11 Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, and an octadecenyl group.

[0092] R 11 Examples of the aryl group having 6 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group.

[0093] R 11 Examples of the aralkyl group having 7 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a benzyl group and a phenethyl group.

[0094] -O-(R 10 -O) z -R 11 Specific examples of the group represented by the formula include, for example, -O-(C2H4-O)5-C 11 H 23 , -O-(C2H4-O)5-C 12 H 25 , -O-(C2H4-O)5-C 13 H 27 , -O-(C2H4-O)5-C 14 H 29 , -O-(C2H4-O)5-C 15 H 31 , -O-(C2H4-O)3-C 13 H 27 , -O-(C2H4-O)4-C 13 H 27 , -O-(C2H4-O)6-C 13 H 27 , -O-(C2H4-O)7-C 13 H 27 Among them, -O-(C2H4-O)5-C 11 H 23 , -O-(C2H4-O)5-C 13 H 27 , -O-(C2H4-O)5-C 15 H 31 , -O-(C2H4-O)6-C 13 H 27 is preferred.

[0095] R 9 Examples of the branched or unbranched alkylene group having 1 to 6 carbon atoms (preferably 1 to 5 carbon atoms) include R 10 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include the same groups as those mentioned above.

[0096] Examples of the compound represented by formula (2-4) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following formula (Si363 manufactured by EVONIK-DEGUSSA), and the compound represented by the following formula can be preferably used. These may be used alone or in combination of two or more. [ka]

[0097] The rubber composition preferably contains carbon black from the viewpoints of wet grip performance, abrasion resistance, and the like.

[0098] Examples of carbon black include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, etc. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., etc.

[0099] The carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. By making the content above the lower limit, the effect of blending carbon black tends to be obtained. Furthermore, the carbon black content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. By making the content below the upper limit, good dispersibility tends to be obtained.

[0100] The nitrogen adsorption specific surface area (N2SA) of carbon black is 30m 2 / g or more is preferable, and 50m 2 / g or more is more preferable, and 70m 2 / g or more is more preferable, and 250m 2 / g or less is preferable, and 180m 2 / g or less is more preferable, and 160m 2By setting the content to be equal to or higher than the lower limit, good wet grip performance tends to be obtained, and by setting the content to be equal to or lower than the upper limit, good dispersion and excellent abrasion resistance tend to be obtained. The nitrogen adsorption specific surface area of ​​carbon black is determined in accordance with JIS K 6217-2:2001.

[0101] The oil (DBP) absorption of the carbon black is preferably 50 ml / 100 g or more, more preferably 90 ml / 100 g or more, and preferably 250 ml / 100 g or less, more preferably 200 ml / 100 g or less, and even more preferably 135 ml / 100 g or less. By setting it above the lower limit, good abrasion resistance tends to be obtained, while by setting it below the upper limit, good dispersion tends to be obtained, and excellent wet grip performance tends to be obtained. The DBP oil absorption of carbon black is measured in accordance with JIS K6217-4:2001.

[0102] The rubber composition contains at least one plasticizer component selected from the group consisting of liquid plasticizers (plasticizers in a liquid state at 25°C) and resins (resin components in a solid state at 25°C).

[0103] The content of the plasticizer component (total content of liquid plasticizer and resin) is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, even more preferably 160 parts by mass or less, and particularly preferably 150 parts by mass or less. By keeping the content within the above range, good wet grip performance and abrasion resistance tend to be obtained.

[0104] The liquid plasticizer is not particularly limited as long as it is a plasticizer that is liquid at 25°C, and examples thereof include oil, liquid diene polymer, and liquid resin. Of these, oil is particularly preferred from the viewpoint of processability and wet grip performance. These may be used alone or in combination of two or more.

[0105] The content (total amount) of the liquid plasticizer is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more, per 100 parts by mass of the rubber component. By setting the content at or above the lower limit, sufficient conformability tends to be imparted. Furthermore, the content is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, even more preferably 160 parts by mass or less, and particularly preferably 150 parts by mass or less. By setting the content at or below the upper limit, good abrasion resistance tends to be obtained. The oil content also includes the amount of oil (extending oil) contained in the rubber (oil-extended rubber).

[0106] As the oil, in addition to the above-mentioned extender oil, conventionally known oils can be used, such as process oils such as paraffinic process oil, aromatic process oil, and naphthenic process oil, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils, and mixtures thereof. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Among these, process oils are preferred, and aromatic process oils are more preferred. Examples of commercially available oils that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0107] The liquid diene polymer has a weight average molecular weight (Mw) of 1.0 x 10 in terms of polystyrene measured by gel permeation chromatography (GPC). 3 ~2.0×10 5 Preferably, it is 3.0 × 10 3 ~1.5×10 4 It is more preferable that: In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0108] Examples of liquid diene polymers include liquid styrene butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene isoprene copolymer (liquid SIR).

[0109] The liquid resin is not particularly limited, but examples thereof include liquid aromatic vinyl polymers, coumarone-indene resins, indene resins, terpene resins, rosin resins, and hydrogenated products thereof.

[0110] Examples of liquid aromatic vinyl polymers include resins obtained by polymerizing α-methylstyrene and / or styrene. Specific examples include liquid resins such as a homopolymer of styrene, a homopolymer of α-methylstyrene, and a copolymer of α-methylstyrene and styrene.

[0111] The liquid coumarone-indene resin is a resin containing coumarone and indene as the main monomer components constituting the resin skeleton (main chain). In addition to coumarone and indene, other monomer components that may be contained in the skeleton include liquid resins of styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0112] Liquid indene resin is a liquid resin that contains indene as the main monomer component that constitutes the skeleton (main chain) of the resin.

[0113] Liquid terpene resins are resins obtained by polymerizing terpene compounds such as α-pinene, β-pinene, camphor, and dipentene, and liquid terpene resins (terpene phenolic resins, aromatic modified terpene resins, etc.) typified by terpene phenols, which are resins obtained using terpene compounds and phenolic compounds as raw materials.

[0114] Examples of liquid rosin resins include liquid rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0115] Commercially available liquid diene polymers and liquid resins include those manufactured by Cray Valley, Kuraray Co., Ltd., and the like.

[0116] The rubber composition may contain a resin (solid resin (resin component): a resin that is in a solid state at room temperature (25° C.)).

[0117] Examples of resins (solid resins) include aromatic vinyl polymers, coumarone-indene resins, indene resins, rosin resins, terpene resins, and acrylic resins. Commercially available products include those from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., and Toagosei Co., Ltd. These resins may be used alone or in combination of two or more. Among these, aromatic vinyl polymers, coumarone-indene resins, terpene resins, and rosin resins are preferred, with coumarone-indene resins being more preferred.

[0118] The content of the resin (solid resin) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. By keeping the content within the above range, good wet grip performance and abrasion resistance tend to be obtained.

[0119] The softening point of the resin (solid resin) is preferably 30° C. or higher, more preferably 60° C. or higher, and even more preferably 80° C. or higher. The softening point is preferably 200° C. or lower, and more preferably 160° C. or lower. By keeping the softening point within the above range, good wet grip performance and abrasion resistance tend to be obtained. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0120] The rubber composition may contain a wax. The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more. Of these, petroleum waxes are preferred, and paraffin wax is more preferred.

[0121] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0122] When the wax is contained, the amount thereof is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component.

[0123] The rubber composition may contain an antioxidant. Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine antioxidants such as quinoline; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred.

[0124] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0125] When an antioxidant is contained, the content thereof is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0126] The rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, for example, products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

[0127] When stearic acid is contained, the amount thereof is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0128] The rubber composition may contain zinc oxide. As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0129] When zinc oxide is contained, the content thereof is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0130] The rubber composition preferably contains sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0131] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0132] When sulfur is contained, the amount thereof is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the rubber component.

[0133] The rubber composition preferably contains a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferred.

[0134] When a vulcanization accelerator is contained, the content thereof is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 7 parts by mass or less, per 100 parts by mass of the rubber component.

[0135] In addition to the above components, the rubber composition may further contain other compounding agents (organic crosslinking agents, etc.) commonly used in the tire industry. The content of these compounding agents is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0136] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0137] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C.

[0138] The rubber composition for treads is used in tire treads. In the case of a tread composed of a cap tread and a base tread, the rubber composition for treads is preferably used in the cap tread.

[0139] The tire of the present invention is produced by a conventional method using the above rubber composition. That is, the rubber composition is extruded in an unvulcanized state to match the shape of each tire component of the tread, and molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0140] The tire tread may be at least partially made of the rubber composition, or may be entirely made of the rubber composition.

[0141] The tire of the present invention may be a pneumatic tire or an airless (solid) tire, with pneumatic tires being preferred. The tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy-duty tire for trucks, buses, etc., a light truck tire, a motorcycle tire, a racing tire (high-performance tire), etc. The tire can also be used as an all-season tire, a summer tire, a studless tire (winter tire), etc. [Example]

[0142] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0143] The various chemicals used in the examples and comparative examples will be collectively described below. SBR: Tufuden 4850 manufactured by Asahi Kasei Corporation (S-SBR, styrene content 40% by mass, vinyl content 47% by mass, oil-extended rubber containing 50 parts by mass of oil per 100 parts by mass of rubber solids) NR:RSS#3 BR: Nipol BR1220 (cis content 97% by mass) manufactured by Zeon Corporation Carbon black: Seast 9SAF (N2SA: 142m) manufactured by Tokai Carbon Co., Ltd. 2 / g, DBP: 115ml / 100g) Silica 1: Ultrasil VN3 (Evonik Degussa, N2SA175m 2 / g) Silica 2: Ultrasil 9100GR (N2SA212m) manufactured by Evonik Degussa 2 / g) Silane coupling agent 1: Si69 (Evonik, bis(3-triethoxysilylpropyl)tetrasulfide) Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Resin: NOVARES C100 (coumarone-indene resin, softening point 100°C) manufactured by Rutgers Chemicals Oil: H&R VIVATEC 500 (TDAE oil) Sorbitan fatty acid ester: Rheodor SP-L10 (sorbitan monolaurate) manufactured by Kao Corporation Glycerin fatty acid ester: Rheodol MS-50 (glycerol monostearate) manufactured by Kao Corporation Zinc oxide: Zinc oxide type 2 (manufactured by Mitsui Mining & Smelting Co., Ltd.) Stearic acid: NOF Corporation Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Sulfur: Powdered sulfur (Karuizawa Iso Co., Ltd.) Vulcanization accelerator 1: Noccelaer D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0144] Examples and Comparative Examples According to the formulation shown in each table, chemicals other than sulfur and vulcanization accelerator are kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. Next, sulfur and vulcanization accelerator are added to the kneaded product obtained, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is molded into the shape of a cap tread, and is laminated together with other tire components to prepare an unvulcanized tire. The unvulcanized tire is then press-vulcanized at 170°C for 10 minutes to obtain a test tire (size: 195 / 65R15).

[0145] The performance of the produced test tires was evaluated by the following methods. The results are shown in the tables. Note that Comparative Example 1-1 in Table 1 and Comparative Example 2-1 in Table 2 are the reference comparative examples.

[0146] (Viscoelasticity test) For each sample taken from the cap tread of the test tire, the 0°C tan δ of the vulcanized rubber composition was measured using a viscoelasticity spectrometer VES manufactured by Iwamoto Seisakusho Co., Ltd. (measurement conditions: measurement temperature 0°C, initial strain 10%, dynamic strain 2.5%, frequency 10 Hz). The 0°C tan δ of the reference comparative example was set to 100 and the result was expressed as an index (wet grip performance index). A higher index indicates better wet grip performance.

[0147] (Wear resistance) Each test tire is fitted to all wheels of a vehicle (domestic FF 2000cc) and the vehicle is driven on a test course with a dry asphalt surface (30°C). The groove depth of the tire tread after a driving distance of 8000 km is measured, and the driving distance when the tire groove depth decreases by 1 mm is calculated and displayed as an index (wear resistance performance index) with the reference comparative example set at 100. The higher the index, the better the wear resistance performance. The index is calculated using the following formula. (Wear resistance performance index) = (mileage for each formulation) / (mileage for the reference comparative example) × 100

[0148] [Table 1]

[0149] [Table 2]

[0150] As shown in each table, examples containing a rubber component, silica, a surfactant, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, and in which the silica content (A) and the plasticizer component content (B) per 100 parts by mass of the rubber component satisfy the above formulas (1) and (2), are expected to be able to significantly improve wet grip performance and abrasion resistance.

Claims

1. The rubber composition includes a rubber component, a surfactant, silica, carbon black, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, the content of the carbon black is 15 to 30 parts by mass and the content of the plasticizer component is 35 to 150 parts by mass relative to 100 parts by mass of the rubber component, The nitrogen adsorption specific surface area of ​​the silica is 175 m ２ / g or more, A rubber composition, wherein the content (A) of the silica and the content (B) of the plasticizer component per 100 parts by mass of the rubber component satisfy the following formulas (1) and (2): 70≦A≦150 (1) B≦A≦B+100 (2) The resin is contained in an amount of 5 to 30 parts by mass relative to the rubber component, The rubber composition has a styrene-butadiene rubber content of 40 to 60% by mass, a butadiene rubber content of 5 to 30% by mass, and an isoprene-based rubber content of 10 to 40% by mass, based on 100% by mass of the rubber component. (However, the following rubber compositions are excluded.) It contains a rubber component, paraffin wax, a nonionic surfactant, and a resin, The paraffin wax contains a normal alkane, the content of the normal alkane is 0.3 to 5.0 parts by mass per 100 parts by mass of the rubber component, the content of the nonionic surfactant is 0.8 to 5.0 parts by mass per 100 parts by mass of the rubber component, the content ratio of the normal alkane to the nonionic surfactant (normal alkane / nonionic surfactant) is 0.3 to 3.0; the nonionic surfactant is at least one selected from the group consisting of a Pluronic nonionic surfactant represented by the following formula (1), a nonionic surfactant represented by the following formula (2) and / or the following formula (3), and a polyether (A), The average mass of the polyethylene oxide having two or more chains contained in the polyether (A) is 85% or less of the mass of the polyethylene oxide contained in the polyether (A). Rubber composition. 【Chemical 1】 (In formula (1), a, b, and c represent natural numbers.) 【Chemistry 2】 (In formula (2), R 1 represents a hydrocarbon group having 6 to 26 carbon atoms, and d represents a natural number.) 【Chemistry 3】 (In formula (3), R 2 and R 3 are the same or different and represent a hydrocarbon group having 6 to 26 carbon atoms, and e represents a natural number.)

2. A rubber composition comprising a rubber component, a surfactant, silica, carbon black, and at least one plasticizer component selected from the group consisting of a liquid plasticizer and a resin, the content of the carbon black is 15 to 30 parts by mass and the content of the plasticizer component is 35 to 150 parts by mass relative to 100 parts by mass of the rubber component, The silica has a nitrogen adsorption specific surface area of ​​175 m 2 / g or more; A rubber composition, wherein the content (A) of the silica and the content (B) of the plasticizer component per 100 parts by mass of the rubber component satisfy the following formulas (1) and (2): 70≦A≦150 (1) B≦A≦B+100 (2) The rubber composition has a surfactant content of 6 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the rubber component.

3. 3. The rubber composition according to claim 1, wherein the amount of the carbon black is 15 to 20 parts by mass based on 100 parts by mass of the rubber component.

4. The rubber composition according to any one of claims 1 to 3, comprising the resin.

5. The resin is contained in an amount of 5 to 30 parts by mass relative to the rubber component, The rubber composition according to any one of claims 2 to 4, wherein the content of the styrene-butadiene rubber is 40 to 60% by mass, the content of the butadiene rubber is 5 to 30% by mass, and the content of the isoprene-based rubber is 10 to 40% by mass, based on 100% by mass of the rubber component.

6. 2. The rubber composition according to claim 1, wherein the surfactant is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the rubber component.

7. 2. The rubber composition according to claim 1, wherein the surfactant is contained in an amount of 5 to 20 parts by mass per 100 parts by mass of the rubber component.

8. The rubber composition according to any one of claims 1 to 7, wherein the surfactant is a nonionic surfactant.

9. The rubber composition according to any one of claims 1 to 8, wherein the plasticizer component is contained in an amount of 80 to 150 parts by mass relative to the rubber component.

10. The rubber composition according to any one of claims 1 to 9, further comprising a mercapto coupling agent.

11. The rubber composition according to any one of claims 1 to 10, wherein the surfactant is a sorbitan fatty acid ester.

12. A tire having a tread made of the rubber composition according to any one of claims 1 to 11.

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