Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires and a tire which are capable of improving overall performance of on-ice steering stability and chipping-resistant performance.SOLUTION: The present invention relates to the rubber composition for tires which contains a rubber component containing an isoprene rubber and a butadiene rubber, silica, carbon black, and a resin component. The following relations are satisfied: (the amount of acetone extraction)≥(the content of the isoprene rubber); (the content of the isoprene rubber)≥(the content of the carbon black); and (the content of the carbon black)≥(the content of the silica).SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Conventionally, various methods for improving driving stability and chipping resistance have been studied (for example, see Patent Documents 1 and 2). However, in recent years, there has been a demand for further improvement in the overall performance of driving stability on ice (driving stability on ice) and chipping resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-334310 [Patent Document 2] JP 2014-012768 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a rubber composition for tires and a tire which can solve the above problems and improve the overall performance of steering stability on ice and chipping resistance. [Means for solving the problem]

[0005] The present invention relates to a rubber composition for tires, which contains a rubber component including an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, wherein the acetone extractable amount is greater than or equal to the content of the isoprene-based rubber, the content of the isoprene-based rubber is greater than or equal to the carbon black content, and the content of the carbon black is greater than or equal to the silica content.

[0006] The cis content of the butadiene rubber is preferably 60 to 90% by mass.

[0007] It is preferable that the ratio of the carbon black content to the silica content is 1.5 or less.

[0008] The resin component preferably contains a terpene resin.

[0009] The terpene resin is preferably a liquid farnesene resin.

[0010] The rubber composition preferably contains vulcanized rubber particles.

[0011] The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area of ​​110 m 2 It is preferable that the molecular weight is 1 / g or more.

[0012] The rubber composition preferably contains a calcium compound.

[0013] The present invention also relates to a tire using the rubber composition. Effect of the Invention

[0014] The present invention provides a rubber composition for tires which contains a rubber component including an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, and in which the acetone extractable amount ≧ the isoprene-based rubber content, the isoprene-based rubber content ≧ the carbon black content, and the carbon black content ≧ the silica content, thereby achieving good overall performance in terms of steering stability on ice and chipping resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The rubber composition for tires of the present invention contains a rubber component including an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, and satisfies the following: acetone extractable amount≧the content of isoprene-based rubber, the content of isoprene-based rubber≧the content of carbon black, and the content of carbon black≧the content of silica.

[0016] The reason why the above-mentioned effects are obtained with the above-mentioned rubber composition is presumed to be as follows. In the above rubber composition, the isoprene-based rubber phase, which has a high molecular weight and a high elastic modulus, can be sufficiently plasticized by increasing the amount of acetone extractables (plasticizer) compared to the amount of isoprene-based rubber. This provides good steering stability on ice, and enables the reinforcing agents silica and carbon black to be efficiently dispersed in the isoprene-based rubber phase, increasing the reinforcing properties of the isoprene-based rubber phase and improving chipping resistance. Furthermore, by setting the amount of reinforcing agent so that the isoprene-based rubber content is greater than or equal to the carbon black content and the carbon black content is greater than or equal to the silica content, a sufficient reinforcing effect on the isoprene-based rubber phase is obtained, and it is believed that chipping resistance is further improved. It is believed that these actions result in a remarkable improvement in the overall performance of steering stability on ice and chipping resistance.

[0017] The rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0018] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be better obtained.

[0019] In this specification, the weight average molecular weight (Mw) can be determined by converting it into standard polystyrene based on the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0020] The total vinyl content in the rubber component is preferably 0.4% by mass or more, more preferably 1.2% by mass or more, and even more preferably 1.6% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0021] Here, the total vinyl content in the rubber component is the total content of vinyl parts contained in the entire rubber component (unit: mass%) and can be calculated by Σ (content of each rubber component × vinyl content in each rubber component / 100). For example, in a 100% rubber component, when the rubber component contains 85% by mass of SBR with a vinyl content of 30% by mass, 5% by mass of SBR with a vinyl content of 20% by mass, and 10% by mass of BR with a vinyl content of 10% by mass, the total vinyl content in the rubber component is 27.5% by mass (=85×30 / 100+5×20 / 100+10×10 / 100).

[0022] The vinyl content in each rubber component can be measured by a nuclear magnetic resonance (NMR) method. In addition, the total vinyl amount in the rubber component is calculated according to the above-mentioned formula in the examples of this specification, but it may also be analyzed from the tire using, for example, a pyrolysis gas chromatograph mass spectrometer (Py-GC / MS) or the like.

[0023] The rubber composition contains an isoprene-based rubber as a rubber component. Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS♯3, TSR20, and other rubbers that are common in the tire industry. Examples of IR include IR2200 and other rubbers that are common in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. 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. Among these, NR is preferred.

[0024] In 100% by mass of the rubber component, the content of the isoprene-based rubber is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0025] The rubber composition contains a butadiene rubber (BR) as a rubber component. The BR is not particularly limited, and examples of the BR that can be used include BRs having a high cis content, such as BR1220 manufactured by Zeon Corporation and BR150B manufactured by Ube Industries, Ltd., BRs containing 1,2-syndiotactic polybutadiene crystals (SPB), such as VCR412 and VCR617 manufactured by Ube Industries, Ltd., and butadiene rubbers synthesized using a rare earth element catalyst (rare earth-based BR), which are commonly used in the tire industry. Of these, rare earth-based BRs are preferred.

[0026] As the rare earth element-based catalyst used in the synthesis of the rare earth-based BR, known catalysts can be used, but lanthanum series rare earth element compounds are preferred, and neodymium-containing compounds (Nd-based catalysts) are more preferred.

[0027] The cis amount (cis content) of BR is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and is preferably 90% by mass or less. Within the above range, the effect tends to be better obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0028] The above-mentioned cis amount of BR means the cis amount of the BR when there is one type of BR, and means the average cis amount when there are multiple types of BR. The average cis content of BR can be calculated by {Σ(content of each BR × cis content of each BR)} / total content of all BRs. For example, when 100% by mass of the rubber component contains 20% by mass of BR with a cis content of 90% by mass and 10% by mass of BR with a cis content of 40% by mass, the average cis content of BR is 73.3% by mass (=(20×90+10×40) / (20+10)).

[0029] In 100% by mass of the rubber component, the content of BR is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0030] Examples of rubber components that can be used other than isoprene-based rubber and BR include diene-based rubbers such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more.

[0031] The rubber component may be modified to introduce a functional group that interacts with a filler such as silica. 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 imide 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 them, an amino group (preferably an amino group in which a hydrogen atom of an 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.

[0032] Specific examples of compounds (modifiers) having the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, and the like.

[0033] The rubber composition contains silica. Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it has a large number of silanol groups. Commercially available products include those from EVONIK, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc. These may be used alone or in combination of two or more.

[0034] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the silica is preferably 140 m 2 / g or more, more preferably 150m 2 / g or more, more preferably 160m 2 / g or more, and preferably 220 m 2 / g or less, more preferably 200 m 2 / g or less, still more preferably 180 m 2 / g or less. When it is within the above range, the effect tends to be obtained more favorably. In addition, the CTAB specific surface area of silica is measured in accordance with ASTM D3765-92.

[0035] The content of silica is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, and preferably 80 parts by mass or less, more preferably 60 parts by mass or less, still more preferably 40 parts by mass or less with respect to 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0036] From the viewpoints of the overall performance such as ice driving stability and chipping resistance performance, in the above rubber composition, it is preferable that the content of silica < the content of isoprene rubber.

[0037] The content of isoprene rubber / the content of silica is preferably 1.2 or more, more preferably 1.4 or more, still more preferably 1.6 or more, and preferably 3.0 or less, more preferably 2.5 or less, still more preferably 2.0 or less. When it is within the above range, the effect tends to be obtained more favorably.

[0038] In these relationships, the content of isoprene rubber is the content in 100% by mass of the rubber component (unit: mass%), and the content of silica is the content with respect to 100 parts by mass of the rubber component (unit: parts by mass).

[0039] From the viewpoints of the overall performance such as ice driving stability and chipping resistance performance, in the above rubber composition, it is preferable that the content of silica < the content of BR.

[0040] The BR content / silica content is preferably 1.5 or more, more preferably 1.8 or more, and even more preferably 2.0 or more, and is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. Within the above ranges, the effect tends to be better.

[0041] In these relationships, the BR content is the content (unit: mass %) in 100% by mass of the rubber component, and the silica content is the content (unit: mass parts) relative to 100 parts by mass of the rubber component.

[0042] The rubber composition preferably contains a silane coupling agent. 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, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl, mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; 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. As commercially available products, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among them, sulfide-based products are preferred.

[0043] The content of silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 8 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, based on 100 parts by mass of silica.When it is within the above range, the effect tends to be better obtained.

[0044] The rubber composition contains carbon black. The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. 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., and the like. These may be used alone or in combination of two or more kinds.

[0045] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 110 m 2 / g or more, more preferably 130m 2 / g or more, more preferably 150m 2 / g or more, and preferably 220m 2 / g or less, more preferably 200m 2 / g or less, more preferably 180m 2 Within the above range, there is a tendency for the effect to be better obtained. The CTAB specific surface area of ​​carbon black is a value measured in accordance with JIS K6217-3:2001.

[0046] The amount of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0047] In the rubber composition, the carbon black content is equal to or greater than the silica content.

[0048] In the rubber composition, the carbon black content / silica content is preferably 1.1 or more, more preferably 1.2 or more, even more preferably 1.3 or more, and is preferably 2.4 or less, more preferably 2.0 or less, even more preferably 1.6 or less, and particularly preferably 1.5 or less. Within the above ranges, the effect tends to be better obtained.

[0049] In these relationships, the carbon black content and the silica content are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0050] In the rubber composition, the content of the isoprene-based rubber is equal to or greater than the content of the carbon black.

[0051] In the rubber composition, the ratio of the isoprene rubber content to the carbon black content is preferably 1.1 or more, and is preferably 2.0 or less, more preferably 1.6 or less, even more preferably 1.4 or less, and particularly preferably 1.3 or less. Within the above range, the effect tends to be better obtained.

[0052] In these relationships, the isoprene-based rubber content is the content (unit: mass %) in 100% by mass of the rubber component, and the carbon black content is the content (unit: mass parts) relative to 100 parts by mass of the rubber component.

[0053] The rubber composition contains a resin component. The resin component is not particularly limited, but aromatic resins and terpene resins can be preferably used. These may be used alone or in combination of two or more. Among them, terpene resins are preferred.

[0054] An aromatic resin is a polymer containing an aromatic monomer as a constituent monomer, and examples of such a resin include a homopolymer obtained by polymerizing one type of aromatic monomer alone, a copolymer obtained by copolymerizing two or more types of aromatic monomers, and a copolymer of an aromatic monomer and another monomer that can be copolymerized with the aromatic monomer.

[0055] Examples of aromatic monomers include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; phenol monomers such as phenol, alkylphenol, and alkoxyphenol; naphthol monomers such as naphthol, alkylnaphthol, and alkoxynaphthol; coumarone, indene, and the like. These may be used alone or in combination of two or more. Among them, styrene monomers are preferred, and styrene and α-methylstyrene are more preferred.

[0056] From the viewpoint of overall performance such as steering stability on ice and chipping resistance, the aromatic resin is preferably an α-methylstyrene resin (such as an α-methylstyrene homopolymer or a copolymer of α-methylstyrene and styrene), and more preferably a copolymer of α-methylstyrene and styrene.

[0057] The content of the aromatic resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0058] Terpene resins are polymers that contain a terpene compound (terpene monomer) as a constituent monomer, and examples of such resins include homopolymers in which one type of terpene compound is polymerized alone, copolymers in which two or more types of terpene compounds are copolymerized, and copolymers of a terpene compound and another monomer that can be copolymerized with the terpene compound.

[0059] Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives represented by the composition 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include farnesene, α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, and the like. These may be used alone or in combination of two or more. Among them, farnesene and β-pinene are preferred, and farnesene is more preferred.

[0060] Examples of monomers that can be copolymerized with terpene compounds include conjugated diene compounds such as 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more. Among these, 1,3-butadiene is preferred.

[0061] From the viewpoint of overall performance such as steering stability on ice and chipping resistance, the terpene resin is preferably a farnesene resin (farnesene homopolymer, copolymer of farnesene and a conjugated diene compound, etc.), and more preferably a copolymer of farnesene and 1,3-butadiene.

[0062] The farnesene resin is preferably a liquid farnesene resin that is in a liquid state at room temperature. The number average molecular weight (Mn) of the liquid farnesene resin is preferably 10,000 or more, more preferably 30,000 or more, more preferably 50,000 or more, and is preferably 300,000 or less, more preferably 200,000 or less, even more preferably 150,000 or less, and particularly preferably 100,000 or less. Within the above ranges, the effect tends to be better obtained.

[0063] The amount of the terpene resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less, based on 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be better obtained.

[0064] Examples of commercially available resins that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0065] The content of the resin component (when a plurality of resins are used in combination, the total content thereof) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0066] From the viewpoint of overall performance such as steering stability on ice and chipping resistance, it is preferable that the content of the isoprene-based rubber in the rubber composition is equal to or greater than the content of the resin component.

[0067] The ratio of the content of isoprene-based rubber to the content of resin component is preferably at least 1, more preferably at least 2, and is preferably at most 5, more preferably at most 4, and even more preferably at most 3. Within the above ranges, the effect tends to be better obtained.

[0068] In these relationships, the isoprene-based rubber content is the content (unit: mass %) in 100% by mass of the rubber component, and the resin component content is the content (unit: mass parts) relative to 100 parts by mass of the rubber component.

[0069] In the rubber composition, the resin component content / silica content is preferably 0.2 or more, more preferably 0.4 or more, and even more preferably 0.6 or more, and is preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. Within the above ranges, the effect tends to be better obtained. In this relationship, the resin component content and the silica content are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0070] In the rubber composition, the resin component content / carbon black content is preferably 0.2 or more, more preferably 0.4 or more, and even more preferably 0.5 or more, and is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.7 or less. Within the above ranges, the effect tends to be better obtained. In this relationship, the resin component content and the carbon black content are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0071] The rubber composition preferably contains vulcanized rubber particles. The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder or the like specified in JIS K 6316:2017 can be used. From the viewpoint of environmental consideration and cost, recycled rubber powder produced from crushed waste tires or the like is preferable. These may be used alone or in combination of two or more types.

[0072] As commercially available vulcanized rubber particles, products from Muraoka Rubber Industries Co., Ltd. and the like can be used.

[0073] The average particle size of the vulcanized rubber particles is preferably 100 μm or more, more preferably 300 μm or more, and even more preferably 400 μm or more, and is preferably 800 μm or less, more preferably 600 μm or less, and even more preferably 500 μm or less. The average particle size of the vulcanized rubber particles is a mass-based average particle size calculated from the particle size distribution measured in accordance with JIS Z 8815:1994.

[0074] The content of the vulcanized rubber particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0075] The rubber composition preferably contains a calcium compound as a processing aid. The calcium compound is a compound containing calcium, and examples thereof include inorganic salts such as calcium oxide, calcium hydroxide, and calcium carbide; and oxoacid salts such as calcium carbonate, calcium nitrate, and calcium sulfate. The oxoacid salts also include fatty acid salts such as calcium acetate and calcium stearate. Examples of calcium compounds that contain calcium compounds include eggshells (main component: calcium carbonate) and WB16 (a mixture of fatty acid calcium, fatty acid amide, and fatty acid amide ester) manufactured by Struktol. These may be used alone or in combination of two or more. Among these, oxoacid salts are preferred, and fatty acid salts (fatty acid calcium) are more preferred.

[0076] In the rubber composition, the content of the calcium compound is, calculated as calcium element, preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.07 parts by mass or more, and is preferably 3.60 parts by mass or less, more preferably 0.80 parts by mass or less, even more preferably 0.60 parts by mass or less, and particularly preferably 0.40 parts by mass or less, relative to 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0077] The rubber composition preferably contains a borate compound as a processing aid. Examples of borate compounds include alkali metal salts such as sodium borate and potassium borate, alkaline earth metal salts such as magnesium borate, and hydrates thereof. These may be used alone or in combination of two or more. Among these, alkali metal salts and hydrates thereof are preferred, sodium borate and hydrates thereof are more preferred, and sodium tetraborate decahydrate (borax) is even more preferred.

[0078] As commercially available borate compounds, products from Kishida Chemical Co., Ltd., Kenei Pharmaceutical Co., Ltd., etc. can be used.

[0079] The content of the borate compound is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1 part by mass or more, and is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. When the content is within the above range, the effect tends to be better.

[0080] The rubber composition may contain oil. Examples of the oil include process oil, vegetable oil, and mixtures thereof. Examples of the process oil include paraffin-based process oil, aromatic process oil, and naphthenic process oil. Examples of the vegetable oil 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Examples of commercially available products include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Nippon Oil & Energy Corporation, Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mill Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like. These may be used alone or in combination of two or more.

[0081] The content of the oil is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 25 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0082] 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 the antioxidant include p-phenylenediamine antioxidants such as quinolinone; 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. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. These may be used alone or in combination of two or more.

[0083] The content of the antioxidant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better.

[0084] 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. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

[0085] The amount of the wax is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0086] The rubber composition may contain stearic acid. As the stearic acid, a conventionally known one can be used, and as a commercially available product, a product from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Corp., Chiba Fatty Acid Corp., etc. can be used. These may be used alone or in combination of two or more kinds.

[0087] The content of stearic acid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0088] The rubber composition may contain zinc oxide. As the zinc oxide, a conventionally known one can be used, and as a commercially available product, it is possible to use 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. These may be used alone or in combination of two or more kinds.

[0089] The amount of zinc oxide is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0090] The rubber composition may contain 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. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

[0091] The amount of sulfur is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, and is preferably 6 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, based on 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be better obtained.

[0092] The rubber composition may contain a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include products from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. These may be used alone or in combination of two or more.

[0093] The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better.

[0094] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides, etc. The content of the additive is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0095] In the rubber composition, the acetone extractable amount is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 45 parts by mass or less, particularly preferably 43 parts by mass or less, and is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more. Within the above ranges, the effect tends to be better obtained. The acetone extractable amount (phr (parts by mass)) can be calculated by the following formula using the value (% by mass) measured by extracting the above-mentioned rubber composition after vulcanization with acetone for 24 hours using a method in accordance with JIS K 6229:2015 and the amount (% by mass) of rubber components determined by acetone extractable amount thermogravimetric analysis (TGA) or the like. Acetone extractables (phr) = Acetone extractables (mass%) / Amount of rubber component (mass%) × 100

[0096] In the above rubber composition, the acetone extractable amount is greater than or equal to the content of the isoprene-based rubber.

[0097] The acetone extractable amount / isoprene rubber content is preferably 1.0 or more, and preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.2 or less, and particularly preferably 1.1 or less. Within the above range, the effect tends to be better obtained.

[0098] In these relationships, the isoprene content is the content (unit: mass%) in 100% by mass of the rubber component, and the acetone extractable amount is measured by performing acetone extraction for 24 hours using the above-mentioned method (unit: parts by mass).

[0099] 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, and then vulcanizing the mixture.

[0100] As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the 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 the 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 the 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. The vulcanization time is usually 5 to 15 minutes.

[0101] The rubber composition can be used (as a rubber composition for tires) for tire components such as treads (cap treads), sidewalls, base treads, under treads, shoulders, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulations, chafers, inner liners, and side reinforcing layers of run-flat tires. Among these, the rubber composition is particularly suitable for treads.

[0102] 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 the tread, etc., and molded together with other tire components in a tire building machine by a normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0103] The above tires (pneumatic tires, etc.) can be used for passenger car tires; truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcing layers; tires with sound-absorbing material having a sound-absorbing material such as sponge in the tire cavity; tires with sealing material having a sealant inside or in the tire cavity that can seal in the event of a puncture; tires with electronic components having electronic components such as sensors and wireless tags inside or in the tire cavity, etc., and are suitable for passenger car tires.

[0104] The size of the tire is not particularly limited, and can be appropriately selected, for example, from a tire width in the range of 100 to 400 mm, an aspect ratio in the range of 25 to 85%, and a rim diameter in the range of 10 to 25 inches. Specific examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 135 / 45R21, 145 / 45R21, 155 / 45R18, 165 / 45R22, 175 / 45R23, 185 / 60R20, 195 / 55R14, 205 / 40R16, 215 / 40R16, 225 / 40R17, 235 / 40R17, 245 / 40R16, 255 / 40R17, 265 / 40R17, 275 / 35R18, 285 / 30R19, and 295 / 45R20.

[0105] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0106] Specific examples of tires that can satisfy the above formula include 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, and the like.

[0107] A tire satisfying the above formula is preferably applied to a pneumatic tire for a passenger vehicle, because a pneumatic tire for a passenger vehicle satisfying the above formula tends to be more suitable for solving the problem of the present invention. EXAMPLES

[0108] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0109] The various chemicals used in the examples and comparative examples will be described below.

[0110] (Rubber component) Isoprene rubber: TSR20 (NR) BR1: N103 manufactured by Asahi Kasei Chemicals Corporation (cis content: 38% by mass, vinyl content: 12% by mass) BR2: BR730 manufactured by JSR Corporation (BR synthesized using a Nd-based catalyst, cis content: 97% by mass, vinyl content: 0.9% by mass)

[0111] (Chemicals other than rubber components) Carbon black 1: N220 (CTAB: 111m 2 / g) Carbon black 2: N134 (CTAB: 135m 2 / g) Carbon Black 3: Prototype (CTAB: 180m 2 / g) Silica: Ultrasil VN3 (CTAB: 165m) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: A / O Mix manufactured by Sankyo Yuka Kogyo Co., Ltd. Resin 1: Sylvatraxx 4401 (copolymer of α-methylstyrene and styrene) manufactured by Arizona Chemical Company Resin 2: Sylvatraxx 4150 (β-pinene resin) manufactured by Arizona Chemical Company Resin 3: FBR-746 (copolymer of farnesene and 1,3-butadiene (liquid farnesene-based resin), Mn: 100,000) manufactured by Kuraray Co., Ltd. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Processing aid 1: WB16 manufactured by Struktol (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, calcium element content: approximately 5% by mass) Processing aid 2: Sodium tetraborate decahydrate manufactured by Kishida Chemical Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanized rubber particles: Muraoka Rubber Industries Co., Ltd. (rubber powder: 30 mesh, average particle size: 500 μm) Eggshell: Eggshell manufactured by Kewpie Egg Co., Ltd. (calcium content: approx. 70% by mass) Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (diphenyl guanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0112] Examples and Comparative Examples According to the composition shown in Table 1, materials other than sulfur and vulcanization accelerator were 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 were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was molded into a tread shape, and laminated together with other tire components to form an unvulcanized tire, which was press-vulcanized for 12 minutes at 150°C to produce a test tire (size: 175 / 60R18). The obtained test tire was used to perform the following evaluations, and the results are shown in Table 1. In Table 1, the rubber content in oil-extended rubber is listed in the rubber column, and the oil content in oil-extended rubber is added to the oil column.

[0113] (Acetone extractables) A sample (vulcanized rubber composition) was taken from the tread of the test tire, and the sample was subjected to acetone extraction for 24 hours according to a method in accordance with JIS K 6229: 2015 to measure the amount of acetone extracted. The amount of acetone extracted (phr (parts by mass)) per 100 parts by mass of the rubber component was calculated using the amount of acetone extracted (% by mass) obtained and the amount of rubber component in the sample (% by mass) determined by TGA.

[0114] (Steering stability on ice) A vehicle fitted with the above test tires on all wheels was measured for 10 laps on ice at a test location of the Nayoro test course in Hokkaido, with temperatures ranging from -1°C to -6°C. A reference tire with a longer lap time than any of the examples and comparative examples was also used to drive under similar conditions. The difference in lap time between each example and comparative example and the reference tire was expressed as an index, with Comparative Example 2 being set at 100. The larger the index, the greater the difference from the lap time of the reference tire (reduction in lap time), indicating superior handling stability on ice (handling stability on wet roads).

[0115] (Chipping resistance) After a vehicle equipped with the above test tires on all wheels was driven 8000 km, the number of chipping occurrences in the tread portion was counted and expressed as an index with Comparative Example 3 being set at 100. A higher index indicates fewer chipping occurrences and better chipping resistance.

[0116] [Table 1]

[0117] As can be seen from Table 1, the Examples were superior to the Comparative Examples in the overall performance (total of all indexes) of the intended steering stability on ice and chipping resistance.

Claims

1. The rubber component includes an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, Acetone extractable amount ≧ the content of the isoprene-based rubber, the content of the isoprene-based rubber is equal to or greater than the content of the carbon black, The ratio of the carbon black content to the silica content is 1.2 or more, The ratio of the butadiene rubber content to the silica content is 1.5 or more, The rubber composition for tires, wherein the resin component contains a terpene resin.

2. The rubber component includes an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, Acetone extractable amount ≧ the content of the isoprene-based rubber, the content of the isoprene-based rubber is equal to or greater than the content of the carbon black, the content of the carbon black is equal to or greater than the content of the silica, The rubber composition for tires, wherein the resin component comprises a farnesene resin.

3. The rubber component includes an isoprene-based rubber and a butadiene rubber, silica, carbon black, and a resin component, Acetone extractable amount ≧ the content of the isoprene-based rubber, the content of the isoprene-based rubber is equal to or greater than the content of the carbon black, the content of the carbon black is equal to or greater than the content of the silica, A rubber composition for tires containing vulcanized rubber particles.

4. The rubber composition for tires according to any one of claims 1 to 3, wherein the cis content of the butadiene rubber is 60 to 90 mass %.

5. 5. The rubber composition for tires according to claim 1, wherein the ratio of the carbon black content to the silica content is 1.5 or less.

6. The rubber composition for tires according to claim 3, wherein the resin component contains a terpene resin.

7. 2. The rubber composition for tires according to claim 1, wherein the terpene resin is a farnesene resin.

8. 3. The rubber composition for tires according to claim 1 or 2, which contains vulcanized rubber particles.

9. The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area of ​​110 m ２ The rubber composition for tires according to any one of claims 1 to 8, wherein the viscosity is 1 / g or more.

10. The rubber composition for tires according to any one of claims 1 to 9, further comprising a calcium compound.

11. A tire using the rubber composition according to any one of claims 1 to 10.

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