Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires that can reversibly change tire performance in response to temperature changes, and can improve on-ice performance, and provide a tire.SOLUTION: A tire rubber composition comprises a mixture of a rubber component and silica surface-treated for pre-bonding to a temperature-responsive compound.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Various performance characteristics have been required of tires for a long time. In particular, it is considered desirable for all-season tires to be able to change their tire performance in response to large changes in outside temperature and road surface conditions. However, little attention has been paid to the ability to change tire performance in response to such changes. Summary of the Invention [Problem to be solved by the invention]

[0003] As for the surface characteristics of tires, for example, depending on the temperature and environment, it is conceivable to improve ice grip performance on ice at low temperatures with a hydrophilic surface, and improve dry grip performance on ice at high temperatures with a hydrophobic surface. However, since the surface characteristics (contact angle with water) of conventional rubber compositions depend on the compounding, one possible method for imparting temperature-dependent changes in surface characteristics through compounding is to compound a temperature-responsive material such as poly(N-isopropylacrylamide) (PNIPAM). However, as a result of extensive research by the present inventors, it was found that such materials have poor compatibility with tire polymers, are soluble in water at low temperatures, and dissolve in water at low temperatures and disappear from the composition in the rain or on ice, creating a new problem in that they are unable to impart reversible changes in surface characteristics.

[0004] The present disclosure aims to solve the above-mentioned problems and to provide a rubber composition for a tire that can reversibly change tire performance in response to temperature changes and improve performance on ice, and a tire. [Means for solving the problem]

[0005] The present disclosure relates to a rubber composition for tires obtained by mixing a rubber component with silica that has been surface-treated to bond in advance with a temperature-responsive compound. [Effects of the Invention]

[0006] According to the present disclosure, the rubber composition for tires is obtained by mixing a rubber component with silica that has been surface-treated to bond in advance with a temperature-responsive compound, and therefore tire performance can be reversibly changed in response to temperature changes, enabling improved performance on ice. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present disclosure provides a rubber composition for tires obtained by mixing a rubber component with silica that has been surface-treated to bond with a temperature-responsive compound in advance (hereinafter also referred to as "surface-treated silica"). The rubber composition can reversibly change tire performance in response to temperature changes, thereby improving performance on ice. It also improves performance on ice while maintaining good abrasion resistance, thereby improving the overall performance of ice performance and abrasion resistance.

[0008] (rubber component) The rubber component usable in the rubber composition is not particularly limited, and rubbers used in the tire field can be used. Examples include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Among these, isoprene rubber, BR, and SBR are preferred from the viewpoint of obtaining the most effective results.

[0009] The diene rubber may be an unmodified diene rubber or a modified diene rubber. Examples of modified diene rubbers include diene rubbers having functional groups that interact with fillers such as silica and carbon black. Specific examples include terminal-modified diene rubbers (terminal-modified diene rubbers having the functional groups at the terminals) in which at least one terminal of the diene rubber has been modified with a compound (modifier) ​​having the functional group, main-chain-modified diene rubbers having the functional groups in the main chain, main-chain-terminal-modified diene rubbers having the functional groups in the main chain and at least one terminal (for example, main-chain-terminal-modified diene rubbers having the functional groups in the main chain and at least one terminal modified with the modifier), and terminal-modified diene rubbers modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having hydroxyl groups or epoxy groups introduced therein. These may be used alone or in combination of two or more.

[0010] Examples of the functional group include functional groups containing at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom. These may be used alone or in combination of two or more.

[0011] 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 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 because they provide a more suitable effect.

[0012] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 can be used, and IRs such as IR2200 can be used, which are commonly used in the tire industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0013] When the rubber composition contains an isoprene-based rubber, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. There is no particular upper limit to the content, but it is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above range, better effects tend to be obtained.

[0014] The BR is not particularly limited, and examples thereof include those commonly used in the tire industry, such as BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), butadiene rubber synthesized using a rare earth catalyst (rare earth BR), and tin-modified butadiene rubber modified with a tin compound (tin-modified BR). Commercially available BRs include those from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation. These may be used alone or in combination of two or more.

[0015] The BR may be either unmodified or modified. The modified BR includes BR having the above-mentioned functional groups.

[0016] From the viewpoint of performance on ice, the cis content of BR is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. In this specification, the cis content (cis-1,4-bond amount) is a value calculated from the signal intensity measured by infrared absorption spectroscopy or NMR analysis.

[0017] When the rubber composition contains BR, the BR content 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. The upper limit of the BR content is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. Within the above range, better effects tend to be obtained.

[0018] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. These may be used alone or in combination of two or more.

[0019] The styrene content of SBR is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, even more preferably 15.0% by mass or more, and particularly preferably 20.0% by mass or more. The upper limit of the styrene content is preferably 60.0% by mass or less, more preferably 50.0% by mass or less, even more preferably 40.0% by mass or less, and particularly preferably 30.0% by mass or less. Within the above range, the effect tends to be more favorable. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0020] The vinyl content of the SBR is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, even more preferably 12.0% by mass or more, and particularly preferably 14.0% by mass or more. The vinyl content is preferably 50.0% by mass or less, more preferably 30.0% by mass or less, even more preferably 20.0% by mass or less, and particularly preferably 18.0% by mass or less. Within the above range, the effect tends to be more favorable. The vinyl content (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0021] In order to obtain better effects, it is desirable that the styrene content (mass %) and vinyl content (mass %) of the SBR satisfy the following formula: Styrene content + vinyl content <50.0% by mass The styrene content plus the vinyl content is preferably 45.0% by mass or less, more preferably 43.0% by mass or less, even more preferably 41.0% by mass or less, and particularly preferably 40.0% by mass or less. The lower limit is preferably 30.0% by mass or more, more preferably 33.0% by mass or more, even more preferably 35.0% by mass or more, and particularly preferably 36.0% by mass or more. Within the above range, the effect tends to be more favorably obtained.

[0022] The mechanism by which such an effect is obtained is not entirely clear, but is presumed to be as follows. The temperature-responsive compound in the surface-treated silica makes the rubber surface hydrophilic at low temperatures, improving friction on ice. It is also believed that the reduced compatibility with the rubber softens the rubber, further improving friction on ice. Furthermore, the use of SBR with a combined styrene and vinyl content below a specified level provides sufficient strength for handling stability and other purposes. Therefore, it is believed that tire performance can be reversibly changed in response to temperature changes, significantly improving performance on ice.

[0023] The styrene content and vinyl content of the SBR mentioned above mean the styrene content and vinyl content of the SBR when there is one type of SBR, and mean the average styrene content and average vinyl content when there are multiple types of SBR. The average styrene content of the SBR can be calculated by {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene content of 40% by mass and 5% by mass of SBR with a styrene content of 25% by mass, the average styrene content of the SBR is 39.2% by mass (=(85×40+5×25) / (85+5)). Similarly, the average vinyl content of the SBRs can be calculated by {Σ(content of each SBR × vinyl content of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBRs with a vinyl content of 30% by mass and 5% by mass of SBRs with a vinyl content of 20% by mass, the average vinyl content of the SBRs is 29.4% by mass (=(85×30+5×20) / (85+5)).

[0024] 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.

[0025] The SBR may be unmodified or modified. The modified SBR includes SBR having the above-mentioned functional groups.

[0026] When the rubber composition contains SBR, the content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0027] In order to obtain the desired effect more effectively in the rubber composition, the total content (mass%) of the isoprene-based rubber and the BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 40% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and particularly preferably 45% by mass or less. Within the above ranges, the desired effect tends to be obtained more effectively.

[0028] From the viewpoint of obtaining better effects in the rubber composition, it is preferable that the rubber composition contains SBR and an isoprene-based rubber and / or BR, and that the content (mass%) of SBR in 100% by mass of the rubber component and the total content (mass%) of the isoprene-based rubber and BR in 100% by mass of the rubber component satisfy the following formula: SBR content > total content of isoprene rubber and BR > 0

[0029] The mechanism by which such an effect is obtained is not entirely clear, but is presumed to be as follows. The temperature-responsive compound in the surface-treated silica makes the rubber surface hydrophilic at low temperatures, improving friction on ice. It is also believed that the reduced compatibility with the rubber softens the rubber, further improving friction on ice. Furthermore, the use of a large amount of SBR provides sufficient strength for handling stability. Therefore, it is believed that tire performance can be reversibly changed in response to temperature changes, resulting in a significant improvement in ice performance.

[0030] The ratio of the content of SBR to the total content of isoprene-based rubber and BR is preferably 1.2 or more, more preferably 1.3 or more, even more preferably 1.4 or more, and particularly preferably 1.5 or more. The upper limit is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.5 or less, and particularly preferably 2.0 or less. Within the above range, the effect tends to be more favorably obtained.

[0031] (Surface-treated silica) In the surface-treated silica (silica that has been surface-treated to bond with a temperature-responsive compound in advance), the temperature-responsive compound is a material that reversibly changes the conformation of the polymer chain in response to temperature changes in water, accompanying hydration and dehydration, and reversibly changes its hydrophilicity and hydrophobicity depending on the temperature. This reversible change is known to be due to the molecular structure that has, within a single molecule, hydrophilic groups capable of hydrogen bonding and hydrophobic groups that are not compatible with water.

[0032] Known temperature-responsive polymers include polymers that exhibit a lower critical solution temperature (LCST, also called lower critical solution temperature or lower critical dissolution temperature) in water and polymers that exhibit an upper critical solution temperature (UCST, also called upper critical solution temperature or upper critical dissolution temperature) in water. These may be used alone or in combination of two or more.

[0033] Polymers that exhibit LCST exhibit a phase transition behavior that is reversible across the LCST. At temperatures above the LCST, the intramolecular and intermolecular hydrophobic bonds strengthen, causing the polymer chains to aggregate and become hydrophobic. On the other hand, at temperatures below the LCST, the polymer chains bind water molecules, become hydrated, and become hydrophilic. Conversely, polymers that exhibit UCST become hydrophobic and insoluble at temperatures lower than the UCST, but become hydrophilic and soluble at temperatures higher than the UCST. In this way, they exhibit reversible phase transition behavior at the UCST boundary. This is thought to be due to the fact that they have multiple amide groups in their side chains, and hydrogen bonds between the side chains act as a driving force to create intermolecular forces, resulting in UCST-type behavior. Among these, polymers that exhibit LCST are preferred from the viewpoint of obtaining greater effects.

[0034] Polymers that exhibit LCST are described below. The polymers exhibiting the LCST may be used alone or in combination of two or more kinds. The polymer exhibiting LCST is not particularly limited as long as it is a polymer exhibiting LCST, but poly(N-substituted (meth)acrylamide) is preferred, and a polymer represented by the following formula (I) is more preferred. [ka] (In the formula, n represents an integer of 1 to 1000, and R 1 , R 2 and R 3 each independently represents a hydrogen atom or a hydrocarbyl group, R 1 and R 2 At least one of the groups is not a hydrogen atom, and R 1 and R 2 may form a ring structure with

[0035] n is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, particularly preferably 20 or more, and is preferably 500 or less, more preferably 300 or less, even more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, and most preferably 30 or less. Within the above ranges, better effects tend to be obtained.

[0036] R 1 and R 2 The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and is preferably 20 or less, more preferably 18 or less, even more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, and most preferably 4 or less. When it is within the above range, the effect tends to be better obtained.

[0037] R 1 and R 2Examples of the hydrocarbyl group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl, and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Of these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0038] R 1 and R 2 The number of carbon atoms in the ring structure formed by is preferably 3 or more, more preferably 4 or more, and is preferably 7 or less, more preferably 5 or less. When it is within the above range, the effect tends to be better.

[0039] R 1 and R 2 The hydrocarbyl group may be branched or unbranched, but is preferably branched.

[0040] R 1 and R 2 Examples of the alkyl group include a hydrogen atom, an alkyl group (especially a branched alkyl group), a cycloalkyl group, and R 1 and R 2 and the combinations shown in Table 1 are more preferred, a combination of a hydrogen atom and an alkyl group (particularly a branched alkyl group) is even more preferred, and a combination of a hydrogen atom and a propyl group (particularly an isopropyl group) is particularly preferred. [Table 1]

[0041] R 3 The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more, preferably 5 or less, more preferably 3 or less, even more preferably 2 or less, and particularly preferably 1. When it is within the above range, the effect tends to be better obtained.

[0042] R 3 The hydrocarbyl group in R1 and R 2 Among these, alkyl groups are preferred.

[0043] R 3 The hydrocarbyl groups may be branched or unbranched.

[0044] R 3 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom.

[0045] Examples of the polymer represented by the above formula (I) include poly(N-alkylacrylamide) polymers such as poly(N-isopropylacrylamide), poly(N-ethylacrylamide), poly(Nn-propylacrylamide), poly(N-ethyl,N-methylacrylamide), poly(N,N-diethylacrylamide), poly(N-isopropyl,N-methylacrylamide), poly(N-cyclopropylacrylamide), poly(N-acryloylpyrrolidine), and poly(N-acryloylpiperidine); Examples of suitable poly(N-alkylmethacrylamide) polymers include poly(N-isopropylmethacrylamide), poly(N-ethylmethacrylamide), poly(Nn-propylmethacrylamide), poly(N-ethyl,N-methylmethacrylamide), poly(N,N-diethylmethacrylamide), poly(N-isopropyl,N-methylmethacrylamide), poly(N-cyclopropylmethacrylamide), poly(N-methacryloylpyrrolidine), and poly(N-methacryloylpiperidine). These may be used alone or in combination of two or more. Among these, poly(N-isopropylacrylamide) and poly(N,N-diethylacrylamide) are preferred, and poly(N-isopropylacrylamide) (PNIPAM) is more preferred.

[0046] PNIPAM is a thermosensitive material that exhibits large changes in surface energy in response to small temperature changes. See, for example, N. Mori et al., Temperature Induced Changes in the Surface Wettability of SBR+PNIPA Films, 292, Macromol. Mater. Eng. 917, 917-22 (2007). PNIPAM has a hydrophobic isopropyl group in the side chain and a hydrophilic amide bond at the base of the isopropyl group. At temperatures below 32°C, the amide bond, which is the hydrophilic portion, forms a hydrogen bond with water molecules, causing the polymer to dissolve in water. However, at temperatures above 32°C, the thermal movement of the molecules becomes intense, the hydrogen bonds are broken, and the isopropyl groups, which are the hydrophobic portions of the side chains, strengthen the hydrophobic bonds within and between molecules, causing the polymer chains to aggregate and become insoluble in water. Thus, the LCST, the switching temperature between the hydrophilic and hydrophobic states of PNIPAM, is approximately 32°C. The contact angle of a water droplet placed on a PNIPAM polymer film changes dramatically with temperature above and below the LSCT. For example, the contact angle of a water droplet placed on a PNIPAM film changes from approximately 60° (hydrophilic) below 32°C to over 93° (hydrophobic) when heated above 32°C.

[0047] As a polymer exhibiting LCST, poly(alkyl vinyl ether) can also be suitably used, and for example, a polymer represented by the following formula (A) is preferred. This tends to produce the desired effect. These may be used alone or in combination of two or more. [ka] (In the formula, m represents an integer of 1 to 1000, and R 4 , R 5 and R 6 each independently represents a hydrogen atom or a hydrocarbyl group.

[0048] m is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, and particularly preferably 20 or more, and is preferably 500 or less, more preferably 300 or less, even more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, and most preferably 30 or less. Within the above ranges, the effect tends to be better obtained.

[0049] R 4 The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and is preferably 20 or less, more preferably 18 or less, even more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, and most preferably 4 or less. When it is within the above range, the effect tends to be better obtained.

[0050] R 5 and R 6 The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more and preferably 5 or less, more preferably 3 or less, even more preferably 2 or less, and particularly preferably 1. When it is within the above range, the effect tends to be better obtained.

[0051] R 4 , R 5 and R 6 Examples of the hydrocarbyl group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl, and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Of these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0052] R 4 is an alkyl group, R 5 and R 6 is preferably a hydrogen atom, and R 4 is an ethyl group, R 5 and R 6 is more preferably a hydrogen atom.

[0053] Examples of polymers represented by the formula (A) include poly(methyl vinyl ether), poly(ethyl vinyl ether), poly(propyl vinyl ether), poly(butyl vinyl ether), poly(pentenyl ether), poly(hexyl vinyl ether), poly(heptyl vinyl ether), and poly(octyl ether). These may be used alone or in combination of two or more. Among these, poly(ethyl vinyl ether) (PEVE) is preferred.

[0054] As a polymer exhibiting LCST, a polymer represented by the following formula (B) is also suitable. This tends to produce the effect more favorably. These may be used alone or in combination of two or more. [ka] (In the formula, m represents an integer of 1 to 1000, and R 7 , R 8 and R 9 each independently represents a hydrogen atom or a hydrocarbyl group.

[0055] m is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, and particularly preferably 20 or more, and is preferably 500 or less, more preferably 300 or less, even more preferably 150 or less, particularly preferably 80 or less, most preferably 40 or less, and most preferably 30 or less. Within the above ranges, the effect tends to be better obtained.

[0056] R 7 The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and is preferably 20 or less, more preferably 18 or less, even more preferably 14 or less, particularly preferably 10 or less, most preferably 6 or less, and most preferably 4 or less. When it is within the above range, the effect tends to be better obtained.

[0057] R 8 and R 9The number of carbon atoms in the hydrocarbyl group is not particularly limited, but is preferably 1 or more and preferably 5 or less, more preferably 3 or less, even more preferably 2 or less, and particularly preferably 1. When it is within the above range, the effect tends to be better obtained.

[0058] R 7 , R 8 and R 9 Examples of the hydrocarbyl group include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, isopentyl, and n-hexyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as methylphenyl and ethylphenyl. Of these, alkyl groups and cycloalkyl groups are preferred, and alkyl groups are more preferred.

[0059] R 7 is an alkyl group, R 8 and R 9 is preferably a hydrogen atom, and R 7 is an n-propyl group or an isopropyl group, R 8 and R 9 is more preferably a hydrogen atom.

[0060] Examples of the polymer represented by the formula (B) include poly(isopropylvinylacrylamide) (PNIPVM, R 7 is an isopropyl group, R 8 and R 9 where R is a hydrogen atom), poly(n-propylvinylacrylamide) (PNNPAM, R 7 is an n-propyl group, R 8 and R 9 is a hydrogen atom), poly(n-butylvinyl acrylamide) (R 7 is an n-butyl group, R 8 and R 9 is a hydrogen atom), poly(tert-butylvinylacrylamide) (R 7 is a tert-butyl group, R 8 and R 9is a hydrogen atom), poly(sec-butylvinyl acrylamide) (R 7 is a sec-butyl group, R 8 and R 9 is a hydrogen atom), poly(methylvinylacrylamide) (R 7 is a methyl group, R 8 and R 9 is a hydrogen atom), poly(ethylvinylacrylamide) (R 7 is an ethyl group, R 8 and R 9 is a hydrogen atom), poly(n-pentylvinylacrylamide) (R 7 is an n-pentyl group, R 8 and R 9 is a hydrogen atom), poly(isopentyl vinyl acrylamide) (R 7 is an isopentyl group, R 8 and R 9 where n is a hydrogen atom). These may be used alone or in combination of two or more. Among these, PNIPVM, PNNPAM, poly(n-butylvinylacrylamide), and poly(tert-butylvinylacrylamide) are preferred, and PNIPVM and PNNPAM are more preferred.

[0061] Examples of polymers exhibiting LCST other than those represented by the above formulas (I), (A), and (B) include poly(N-vinyl-caprolactam) represented by the following formula (II) (LSCT: about 31°C), poly(2-alkyl-2-oxazoline) represented by the following formula (III) (LSCT: about 62°C when R is an ethyl group, about 36°C when R is an isopropyl group, and about 25°C when R is an n-propyl group), alkyl-substituted cellulose (e.g., methylcellulose represented by the following formula (IV) (LSCT: about 50°C), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose), poly(N-ethoxyethyl acrylamide) (LSCT: about 35°C), poly(N-ethoxyethyl methacrylamide) (LSCT: about 45°C), poly(N-tetrahydro furfuryl acrylamide) (LSCT: about 28°C), poly(N-tetrahydrofurfuryl methacrylamide) (LSCT: about 35°C), polyvinyl methyl ether, poly[2-(dimethylamino)ethyl methacrylate], poly(3-ethyl-N-vinyl-2-pyrrolidone), hydroxyl butyl chitosan, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monooleate, poly(ethylene glycol) methacrylate having 2 to 6 ethylene glycol units, polyethylene glycol-co-polypropylene glycol (preferably having 2 to 8 ethylene glycol units and 2 to 8 polypropylene units, more preferably a compound of formula (A)), ethoxylated iso-C 13 H 27Examples of suitable ethylene glycol ethers include ethylene glycols (preferably those having an ethoxylation degree of 4 to 8), polyethylene glycols having 4 to 50, preferably 4 to 20, ethylene glycol units, polypropylene glycols having 4 to 30, preferably 4 to 15, propylene glycol units, monomethyl, dimethyl, monoethyl, and diethyl ethers of polyethylene glycols having 4 to 50, preferably 4 to 20, ethylene glycol units, and monomethyl, dimethyl, monoethyl, and diethyl ethers of polypropylene glycols having 4 to 50, preferably 4 to 20, propylene glycol units. These may be used alone or in combination of two or more. (A)HO-[-CH2-CH2-O] x -[-CH(CH3)-CH2-O] y -[-CH2-CH2-O] z -H (wherein y=3 to 10 and x and z=1 to 8, where y+x+z is 5 to 18) [ka] (In formulas (II) to (IV), n is the same as n in formula (I) above. In formula (III), R is an alkyl group selected from an n-propyl group, an isopropyl group, or an ethyl group.)

[0062] Examples of polymers that exhibit LCST other than those mentioned above include a copolymer of N-isopropylacrylamide and butyl acrylate, a block copolymer of N-isopropylacrylamide and polyethylene oxide, a copolymer of N-isopropylacrylamide and a fluorine monomer, a polymer composite of poly-N-acetylacrylamide and polyethylene oxide, a polymer composite of poly-N-acetylacrylamide and polyacrylamide, a polymer composite of a copolymer of N-acetylacrylamide and acrylamide and polyacrylamide, a copolymer of N-acryloylglycinamide and N-acetylacrylamide, a copolymer of 2-methoxyethyl acrylate and N,N-dimethylacrylamide, a copolymer of the compound represented by the following formula 1 and N,N-dimethylacrylamide, poly(N,N-dimethyl(acrylamidopropyl)ammonium propane sulfate), a copolymer of N,N-diethylacrylamide and maleic anhydride, a copolymer of N,N-diethylacrylamide and dimethyl fumarate, a copolymer of N,N-diethylacrylamide and hydroxyethyl methacrylate,Copolymer of N-diethylacrylamide and butadiene, polymer complexes of polyvinyl alcohol and polyvinyl alcohol hydrolysate with polyacrylamide, N-acryloyl asparagine amide polymer, N-acryloyl glutamine amide polymer, N-methacryloyl asparagine amide polymer, copolymer of N-acryloyl glycinamide and biotin methacrylamide derivative, copolymer of N-acryloyl glycinamide and N-acryloyl asparagine amide, biotin-immobilized temperature-responsive magnetic particles (particles obtained by reacting N-acryloyl glycinamide, methacrylated magnetic particles and biotin monomers), poly(sulfobetaine methacrylamide), N-vinyl-n-butylamide and non- Copolymers of water and maleic acid, copolymers of N-vinyl-n-butylamide and dimethyl fumarate, copolymers of N-vinyl-n-butylamide and hydroxyethyl methacrylate, copolymers of N-vinyl-n-butylamide and butadiene, polyesteramides, polyetheramides, copolymers of ethylene oxide and propylene oxide, monoaminated copolymers of ethylene oxide and propylene oxide, polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymers, polymer composites of polyethylene oxide and polyvinyl alcohol, maltopentaose-modified polypropylene oxide, poly(lactide-co-glycolide)-polyethylene oxide-polylactide Triblock copolymers, copolymers of 2-methoxyethyl acrylate and acryloylmorpholine, copolymers of 2-methoxyethyl acrylate and N-vinylpyrrolidone, copolymers of 2-methoxyethyl acrylate and 2-hydroxyethyl acrylate, copolymers of 2-methoxyethyl acrylate and methoxytriethylene glycol acrylate, poly[2-(2-ethoxyethoxy)ethyl acrylate], poly(2-(2-ethoxyethoxy)ethyl acrylate-co-2-(methoxyethoxy)ethyl methacrylate, poly(2-(N,N-dimethylaminoethyl) methacrylate), copolymer of N-vinylcaprolactam and hydroxyethyl methacrylate, copolymer of methyl vinyl ether and hydroxyethyl methacrylate, N-vinylcaprolactam polymer, copolymer of N-vinylcaprolactam and maleic anhydride, copolymer of N-vinylcaprolactam and dimethyl fumarate, copolymer of N-vinylcaprolactam and butadiene, copolymer of N-vinylcaprolactam, vinylpyrrolidine and glycidyl methacrylate, copolymer of N-vinylcaprolactam, vinylpyrrolidine and methacrylic acid, copolymer of N-vinylcaprolactam, vinylpyrrolidone and α,Copolymers of α-dimethyl-meta-isopropenyl benzyl isocyanate, copolymers of N-vinyl caprolactam, vinyl pyrrolidone and hydroxyethyl methacrylate, poly(1-ethyl-3-vinyl-2-imidazolidone), poly(1-methyl-3-vinyl-2-imidazolidone), poly(1-n-propyl-3-vinyl-2-imidazolidone), poly(1-isopropyl-3-vinyl-2-imidazolidone), poly(1-acetyl-3-vinyl-2-imidazolidone), poly(1-propionyl-3-vinyl-2-imidazolidone), copolymers shown in the following formula 2, poly(N-vinyl-2-imidazolidone compound), copolymers of 2-hydroxyethyl vinyl ether and vinyl acetate, copolymers of diethylene glycol monovinyl ether and vinyl acetate, copolymers of methyl vinyl ether and maleic anhydride, copolymers of methyl vinyl ether and dimethyl fumarate Examples of suitable polymers include copolymers with N-(2-hydroxyethyl)-L-glutamine, carbamoylated polyamino acids, polymers of compounds represented by the following formula 3, polymers of compounds represented by the following formula 4, poly(orthoesters) having pendant [N-(2-hydroxyethyl)-L-glutamine] groups, polyacetal-poly[N-(2-hydroxyethyl)-L-glutamine]-polyacetal triblock copolymers, poly[N-(2-hydroxyethyl)-L-glutamine]-poly(orthoesters)-poly[N-(2-hydroxyethyl)-L-glutamine] triblock copolymers, poly[N-(2-hydroxyethyl)-L-glutamine]-polyacetal diblock copolymers, amino-terminated poly[N-(2-hydroxyethyl)-L-glutamine], amino-terminated poly(orthoesters), amino-terminated polyacetals, cellulose triacetate, magnetic nanoparticles, polystyrenes having amino groups, and glycoluril polymers. These may be used alone or in combination of two or more. [ka]

[0063] The weight-average molecular weight of the temperature-responsive polymer is preferably 330 or more, more preferably 560 or more, even more preferably 1130 or more, and is preferably 57000 or less, more preferably 34000 or less, even more preferably 17000 or less. Within the above ranges, better effects tend to be obtained.

[0064] The phase transition temperature (lower critical solution temperature (LCST) or upper critical solution temperature (UCST)) of the temperature-responsive polymer is preferably -50°C or higher, more preferably -40°C or higher, even more preferably -30°C or higher, particularly preferably -20°C or higher, most preferably -10°C or higher, even most preferably 0°C or higher, still most preferably 5°C or higher, and is preferably 60°C or lower, more preferably 50°C or lower, even more preferably 40°C or lower, particularly preferably 35°C or lower, most preferably 30°C or lower, even most preferably 25°C or lower, and still most preferably 20°C or lower. Within the above range, better effects tend to be obtained. In this specification, the phase transition temperature of a temperature-responsive polymer is measured using a temperature-controlled spectrophotometer. A 10% by mass aqueous solution of the temperature-responsive polymer is placed in a cell, covered with parafilm to prevent evaporation, and a temperature sensor is attached to the cell. The experiment is performed at a measurement wavelength of 600 nm, an intake temperature of 0.1°C, and a heating rate of 0.1°C. The phase transition temperature is defined as the temperature at which the transmittance reaches 90%.

[0065] The temperature-responsive compound can be synthesized by known methods, such as by polymerizing a monomer by irradiation or by solution polymerization. It can also be synthesized by the method described in Anal. Chem., 68, 100-105 (1996). Commercially available products can also be used.

[0066] In the surface-treated silica (silica that has been subjected to a surface treatment to bond with a temperature-responsive compound in advance), the silica (raw silica to be surface-treated) is not particularly limited, and examples thereof include dry-process silica (anhydrous silicic acid) and wet-process silica (hydrated silicic acid). These may be used alone or in combination of two or more. Among these, wet-process silica is preferred because it has a large number of silanol groups.

[0067] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0068] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 150m 2 / g or more. In addition, the N2SA is preferably 300m 2 / g or less, more preferably 250m 2 / g or less, more preferably 230m 2 Within the above range, there is a tendency for the effect to be better obtained. The N2SA of silica can be measured in accordance with ASTM D3037-81.

[0069] In the surface-treated silica, the temperature-responsive compound and silica can be bonded by any known method, such as contacting the temperature-responsive compound with a silica dispersion (a dispersion of silica in a solvent such as water) to allow bonding, reaction, or the like.

[0070] When the temperature-responsive compound is bonded to and reacted with silica, the amount of the temperature-responsive compound added per 100 parts by mass of silica is, from the viewpoint of obtaining a better effect, preferably 40 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 80 parts by mass or more, and 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.

[0071] From the viewpoint of promoting bonding and reaction between the temperature-responsive compound and silica, it is preferable to contact the temperature-responsive compound with the silica dispersion under a predetermined pH condition. The pH is preferably 10.0 or less, more preferably 9.5 or less, and even more preferably 9.0 or less, and is preferably 6.5 or more, more preferably 7.0 or more, and even more preferably 7.5 or more. The pH can be adjusted by a known method, such as adding an acid or alkali.

[0072] The temperature during the bonding and reaction between the temperature-responsive compound and silica is preferably 10° C. or higher, more preferably 15° C. or higher, and preferably 50° C. or lower, more preferably 40° C. or lower, and even more preferably 30° C. or lower. The reaction time is preferably 60 minutes or longer, more preferably 120 minutes or longer, and even more preferably 150 minutes or longer, and preferably 24 hours or shorter, more preferably 18 hours or shorter, and even more preferably 12 hours or shorter.

[0073] In the surface-treated silica produced by the bonding, reaction, or the like, the amount of the temperature-responsive compound attached per 100 parts by mass of silica 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, from the viewpoint of obtaining a better effect, and is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less.

[0074] In the rubber composition, the content of the surface-treated silica relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0075] (Other silica materials) The rubber composition uses the surface-treated silica as the silica material, but from the viewpoint of obtaining a better effect, it is preferable to include, as another silica material, silica that has not been subjected to a surface treatment for bonding with a temperature-responsive compound in advance (hereinafter also referred to as "untreated silica"). Here, in this specification, the silica material means a material containing silica, and includes the surface-treated silica as well as other silica-containing materials.

[0076] Examples of untreated silica include silica that has not been subjected to a surface treatment. Examples of untreated silica include the silica (dry process silica, wet process silica, etc.) used as a raw material for producing the surface-treated silica. Examples of untreated silica also include silica that has been surface-treated in advance to bond with a compound other than the temperature-responsive compound. Among these, silica that has not been surface-treated, such as the dry process silica and wet process silica, is preferred. The N2SA of untreated silica is preferably in the same range as that of the silica (raw material silica to be surface-treated).

[0077] The mechanism by which such an effect is obtained is not entirely clear, but is presumed to be as follows. When both the surface-treated silica and the untreated silica are compounded into a rubber component, the hydrophilicity of the surface-treated silica changes due to the temperature-responsive compound, making the rubber surface hydrophilic at low temperatures, enhancing water removal and improving friction on ice. Furthermore, the hydrophilic nature of the surface-treated silica reduces its compatibility with rubber, reducing its reinforcing properties as a filler, softening the rubber and thereby improving friction on ice. Furthermore, the combined use of untreated silica provides sufficient strength necessary for handling stability and other purposes. Additionally, because the surface-treated silica is a material in which the temperature-responsive compound and silica are bonded, it is prevented from eluting in water, reversibly improving grip performance on ice. Therefore, it is presumed that a rubber composition obtained by mixing the surface-treated silica and the untreated silica can reversibly change tire performance in response to temperature changes and significantly improve ice performance.

[0078] In the rubber composition, the content of the untreated silica per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, even more preferably 80 parts by mass or less, particularly preferably 70 parts by mass or less. When the content is within the above range, the effect tends to be more favorably obtained.

[0079] In the rubber composition, the compounding ratio of the surface-treated silica to the untreated silica (content (parts by mass) of the surface-treated silica / content (parts by mass) of the untreated silica) is preferably 95 / 5 to 50 / 50, more preferably 90 / 10 to 60 / 40, and even more preferably 88 / 12 to 70 / 30, from the viewpoint of obtaining better effects.

[0080] In the rubber composition, the total amount of the silica materials (the total content of the surface-treated silica and the untreated silica) is preferably more than 40 parts by mass, more preferably more than 50 parts by mass, even more preferably more than 70 parts by mass, and particularly preferably more than 75 parts by mass, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less. Within the above range, better effects tend to be obtained.

[0081] (Silane coupling agent) 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, 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 Momentive's NXT and NXT-Z; 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. These compounds may be used alone or in combination of two or more. Among these, sulfide-based and mercapto-based compounds are preferred because they provide better effects.

[0082] As the silane coupling agent, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used.

[0083] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, relative to 100 parts by mass of the total amount of the silica material (total content of the surface-treated silica and the untreated silica).Within the above range, the effect tends to be better.

[0084] (Other fillers) The rubber composition may contain fillers other than the surface-treated silica and untreated silica. The other filler is not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica. Of these, carbon black is preferred.

[0085] In the rubber composition, the content of the filler (total content of the fillers) is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 110 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0086] In the rubber composition, the total amount of the silica material (total content of the surface-treated silica and the untreated silica) in 100% by mass of the filler is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more. There is no particular upper limit, but it is preferably 95% by mass or less, and more preferably 93% by mass or less. Within the above range, better effects tend to be obtained.

[0087] Carbon black that can be used in the rubber composition is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products that can be used 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.

[0088] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m 2 / g or more is preferable, and 70m 2 / g or more is more preferable, and 90m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 Within the above range, the effect tends to be better. The nitrogen adsorption specific surface area of ​​carbon black can be determined according to JIS K6217-2:2001.

[0089] In the rubber composition, the carbon black content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above range, better effects tend to be obtained.

[0090] (plasticizer) The rubber composition may contain a plasticizer. In this specification, the plasticizer refers to a material that imparts plasticity to the rubber component, and examples thereof include liquid plasticizers (plasticizers that are liquid (liquid) at 25° C.) and solid plasticizers (plasticizers that are solid at 25° C.). These may be used alone or in combination of two or more.

[0091] The amount of plasticizer (total amount of liquid plasticizer and solid plasticizer) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the amount is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, better effects tend to be obtained. The amount of plasticizer included includes the amount of oil contained in rubber (oil-extended rubber) and sulfur (oil-containing sulfur).

[0092] Examples of liquid plasticizers include oils, liquid polymers (liquid resins, liquid diene polymers, etc.), essential oils derived from natural products such as turpentine, and ester-based plasticizers. Examples of solid plasticizers include solid resins that are solid at 25°C and are commonly used in the tire industry. These may be used alone or in combination of two or more. Of these, the liquid plasticizer is preferably at least one selected from the group consisting of oils, liquid polymers, and liquid resins, more preferably oils, and even more preferably process oils.

[0093] The oil is not particularly limited, and conventionally known oils can be used, such as process oils such as paraffinic process oil, aromatic process oil, naphthenic process oil, low PCA (polycyclic aromatic) process oil such as TDAE or MES, vegetable oil, and mixtures thereof. These may be used alone or in combination of two or more. Of these, paraffinic process oil is preferred.

[0094] As the oil, for example, 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 KK, Fuji Kosan Co., Ltd., etc. can be used.

[0095] Examples of liquid resins include terpene-based resins (including terpene phenol resins and aromatic modified terpene resins) that are liquid at 25°C, rosin resins, styrene-based resins, C5-based resins, C5C9-based resins, coumarone-indene-based resins (including coumarone and indene simple resins), olefin-based resins, polyurethane resins, and acrylic resins.

[0096] Examples of the liquid resin 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, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0097] Examples of liquid diene polymers include liquid styrene butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene isoprene copolymers (liquid SIR), liquid styrene butadiene styrene block copolymers (liquid SBS block polymers), and liquid styrene isoprene styrene block copolymers (liquid SIS block polymers), which are liquid at 25° C. The terminals or main chains of these polymers may be modified with polar groups.

[0098] As the liquid diene polymer, for example, products manufactured by Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0099] The content of the liquid plasticizer (preferably oil) per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. The upper limit of the content is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. Within the above range, better effects tend to be obtained. The amount of liquid plasticizer included includes the amount of oil contained in rubber (oil-extended rubber) and sulfur (oil-containing sulfur).

[0100] As the solid plasticizer, solid resins commonly used in tire compounds can be used. Specific examples include terpene resins, rosin resins, styrene resins, olefin resins, C5 resins, C9 resins, C5 / C9 resins, coumarone resins, indene resins, coumarone-indene resins, acrylic resins, and urethane resins. These may be used alone or in combination, or the resin itself may be a copolymer of monomer components derived from multiple sources.

[0101] Examples of solid plasticizers 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, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0102] The softening point of the resin is preferably 30° C. or higher, more preferably 50° C. or higher, even more preferably 80° C. or higher, and is preferably 200° C. or lower, more preferably 160° C. or lower, even more preferably 140° C. or lower, and particularly preferably 120° C. or lower. By keeping the softening point within the above range, the above effects tend to be more suitably obtained. In this specification, 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.

[0103] The content of the solid plasticizer (preferably the resin) per 100 parts by mass of the rubber component is preferably 30 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less, and may be 0 part by mass. When the content is within the above range, better effects tend to be obtained.

[0104] In the rubber composition, the compounding ratio of the content of the surface-treated silica to the content of the plasticizer (the content (parts by mass) of the surface-treated silica per 100 parts by mass of the rubber component / the content (parts by mass) of the plasticizer per 100 parts by mass of the rubber component) is preferably 0.30 or more, more preferably 0.50 or more, even more preferably 0.70 or more, and particularly preferably 1.00 or more. The upper limit is preferably 2.50 or less, more preferably 2.00 or less, even more preferably 1.50 or less, and particularly preferably 1.30 or less. Within the above range, better effects tend to be obtained.

[0105] In the rubber composition, the compounding ratio of the total amount of the silica materials (the total content of the surface-treated silica and the untreated silica) to the content of the plasticizer (total amount (parts by mass) of the silica materials per 100 parts by mass of the rubber component / content (parts by mass) of the plasticizer per 100 parts by mass of the rubber component) is preferably 2.5 or more, more preferably 3.5 or more, even more preferably 3.7 or more, and particularly preferably 4.0 or more. The upper limit is preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.2 or less, and particularly preferably 5.0 or less. Within the above range, better effects tend to be obtained.

[0106] In the rubber composition, the compounding ratio of the content of the surface-treated silica to the content of the liquid plasticizer (the content (parts by mass) of the surface-treated silica per 100 parts by mass of the rubber component / the content (parts by mass) of the liquid plasticizer per 100 parts by mass of the rubber component) is preferably 0.30 or more, more preferably 0.50 or more, even more preferably 0.70 or more, and particularly preferably 1.00 or more. The upper limit is preferably 2.50 or less, more preferably 2.00 or less, even more preferably 1.50 or less, and particularly preferably 1.30 or less. Within the above range, better effects tend to be obtained.

[0107] In the rubber composition, the compounding ratio of the total amount of the silica materials (the total content of the surface-treated silica and the untreated silica) to the content of the liquid plasticizer (total amount (parts by mass) of the silica materials per 100 parts by mass of the rubber component / content (parts by mass) of the liquid plasticizer per 100 parts by mass of the rubber component) is preferably 2.5 or more, more preferably 3.5 or more, even more preferably 3.7 or more, and particularly preferably 4.0 or more. The upper limit is preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.2 or less, and particularly preferably 5.0 or less. Within the above range, better effects tend to be obtained.

[0108] In the rubber composition, the compounding ratio of the content of the surface-treated silica to the total content of the liquid resin and the liquid diene-based polymer (the content (parts by mass) of the surface-treated silica per 100 parts by mass of the rubber component / the total content (parts by mass) of the liquid resin and the liquid diene-based polymer per 100 parts by mass of the rubber component) is preferably 0.30 or more, more preferably 0.50 or more, even more preferably 0.70 or more, and particularly preferably 1.00 or more. The upper limit is preferably 2.50 or less, more preferably 2.00 or less, even more preferably 1.50 or less, and particularly preferably 1.30 or less. Within the above range, better effects tend to be obtained.

[0109] In the rubber composition, the compounding ratio of the total amount of the silica materials (the total content of the surface-treated silica and the untreated silica) to the total content of the liquid resin and the liquid diene-based polymer (total amount (parts by mass) of the silica materials per 100 parts by mass of the rubber component / total content (parts by mass) of the liquid resin and the liquid diene-based polymer per 100 parts by mass of the rubber component) is preferably 2.5 or more, more preferably 3.5 or more, even more preferably 3.7 or more, and particularly preferably 4.0 or more. The upper limit is preferably 8.0 or less, more preferably 7.0 or less, even more preferably 6.0 or less, and particularly preferably 5.0 or less. Within the above range, better effects tend to be obtained.

[0110] In the rubber composition, the compounding ratio of the content of the surface-treated silica to the content of the resin (the content (parts by mass) of the surface-treated silica per 100 parts by mass of the rubber component / the content (parts by mass) of the resin per 100 parts by mass of the rubber component) is preferably 1.0 or more, more preferably 1.5 or more, even more preferably 1.8 or more, and particularly preferably 2.0 or more. The upper limit is preferably 5.0 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. Within the above range, better effects tend to be obtained.

[0111] In the rubber composition, the compounding ratio of the total amount of the silica materials (the total content of the surface-treated silica and the untreated silica) to the content of the resin (total amount (parts by mass) of the silica materials per 100 parts by mass of the rubber component / content (parts by mass) of the resin per 100 parts by mass of the rubber component) is preferably 5.0 or more, more preferably 7.0 or more, even more preferably 7.5 or more, and particularly preferably 8.0 or more. The upper limit is preferably 20.0 or less, more preferably 16.0 or less, even more preferably 12.0 or less, and particularly preferably 10.0 or less. Within the above range, better effects tend to be obtained.

[0112] The mechanism by which the above-mentioned effects are obtained by adjusting the amount of the surface-treated silica, the amount of untreated silica, the amount of plasticizer, the amount of liquid plasticizer, the amount of liquid resin, the amount of liquid diene polymer, the amount of resin, etc. is not entirely clear, but is presumed to be as follows. The temperature-responsive compound in the surface-treated silica makes the rubber surface hydrophilic at low temperatures, improving friction on ice. It is also believed that the reduced compatibility with the rubber softens the rubber, further improving friction on ice. The combined use of untreated silica also provides sufficient strength necessary for handling stability, etc. Furthermore, by mixing the amount of surface-treated silica, untreated silica, plasticizer, liquid plasticizer, liquid resin, liquid diene polymer, and resin in a predetermined ratio, it is believed that the effect of improving friction on ice can be further enhanced. Therefore, it is believed that tire performance can be reversibly changed in response to temperature changes, resulting in a significant improvement in ice performance.

[0113] (Other materials) 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.

[0114] 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.

[0115] The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, particularly preferably 3 parts by mass or less, and most preferably 2 parts by mass or less. Within the above ranges, the effect tends to be better.

[0116] The rubber composition preferably contains a vulcanization accelerator. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; 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-benzothiazolyl sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators are preferred.

[0117] As the vulcanization accelerator, for example, products manufactured by Kawaguchi Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Rhein Chemie AG, etc. can be used.

[0118] The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0119] The rubber composition preferably contains stearic acid. As the stearic acid, conventionally known ones can be used, for example, products available from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0120] The amount of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. Furthermore, the amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0121] 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.

[0122] The amount of zinc oxide per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[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-based antioxidants such as quinoline; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based 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-based antioxidants and quinoline-based antioxidants are preferred, and p-phenylenediamine-based antioxidants are more 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] The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be more favorably obtained.

[0126] The rubber composition may contain 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.

[0127] 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.

[0128] The wax content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. The wax content is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0129] In addition to the above components, the rubber composition may contain additives commonly used in the tire industry, such as vulcanizing agents other than sulfur (e.g., organic crosslinking agents, organic peroxides), etc. The content of each of these components is preferably 0.1 part by mass or more and preferably 200 parts by mass or less per 100 parts by mass of the rubber component.

[0130] The rubber composition can be produced, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0131] As for kneading conditions, in the base kneading step in which additives other than the crosslinking agent (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 80 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.

[0132] The rubber composition can be used, for example, in tire components (as a rubber composition for tires), and is particularly suitable for use in treads (cap treads).

[0133] The tire of the present disclosure is manufactured by a conventional method using the rubber composition described above. That is, the rubber composition, to which various additives are optionally added, is extruded in an unvulcanized state to match the shapes of the tire components such as the tread, molded in a conventional manner on a tire building machine, and bonded together with other tire components to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to manufacture the tire.

[0134] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0135] The above-mentioned tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy load tire (such as a truck or bus tire), a motorcycle tire, a racing tire, a winter tire (a studless tire, a snow tire, a studded tire), an all-season tire, a run-flat tire, an aircraft tire, a mining tire, etc. In particular, the tire can be suitably used as a winter tire or an all-season tire because of its good performance on ice, and further, the tire performance can be reversibly changed in response to a temperature change, so the tire can be particularly suitably used as an all-season tire. [Example]

[0136] The various chemicals used in the following Examples and Comparative Examples will be collectively described below. SBR1: Nipol 1502 (E-SBR, styrene content: 23.5% by mass, vinyl content: 16% by mass) manufactured by Zeon Corporation SBR2: SL563 manufactured by JSR Corporation (styrene content 20% by mass, vinyl content 55.5% by mass) BR: BR150B (cis content: 98% by mass) manufactured by Ube Industries, Ltd. NR:TSR20 (natural rubber) Carbon black: Seast N220 (N2SA: 111m) manufactured by Mitsubishi Chemical Corporation 2 / g, DBP: 115ml / 100g) Silica (untreated silica): Ultrasil VN3 (silica without surface treatment, N2SA: 175 ml) manufactured by Evonik Tegussa 2 / g) Surface-treated silica 1: Preparation Examples 1-1 to 1-2 below Surface-treated silica 2: Preparation Examples 2-1 to 2-2 below Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Tegussa Wax: Ozoace wax manufactured by Nippon Seiro Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Oil: PS-32 manufactured by Idemitsu Kosan Co., Ltd. Liquid diene polymer: Sartomer's Licon 150 (liquid butadiene polymer, Mn5200) Resin: SYLVARES SA85 (copolymer of α-methylstyrene and styrene, softening point 85°C) manufactured by Arizona Chemical Stearic acid: NOF Corporation stearic acid Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator: Noccela NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0137] <Production Example 1-1: Synthesis of PNIPAM> A nitrogen-purged glass flask was charged with 11.32 g of N-isopropylacrylamide (NIPAM monomer), 25 mL of toluene, and stirred at room temperature for 30 minutes to form a homogeneous solution. Then, 1.10 g of 2,2'-azobis(isobutyronitrile) (AIBN) was added and the mixture was refluxed for 3 hours. Thin-layer chromatography (silica gel) of the reaction mixture confirmed the disappearance of the spot corresponding to the NIPAM monomer (Rf value 0.8) and the appearance of a new spot corresponding to the NIPAM polymer (PNIPAM). The toluene solvent was removed using a rotary evaporator, and the remaining white powder was dried at a reduced pressure of 0.1 Pa or less at 80 °C for 8 hours to obtain PNIPAM in 95% yield. After preparing a 1% by mass aqueous solution of PNIPAM with water, the PNIPAM aqueous solution was heated from 20 to 40°C and its appearance was confirmed. It was found to be colorless and clear at temperatures below 32°C, but cloudy at temperatures above 32°C. The Mw was 2,000.

[0138] <Production Example 1-2: Production of Surface-Treated Silica 1> Under the following reaction conditions, 10 g of the PNIPAM obtained in Production Example 1-1 and 100 g of an aqueous silica dispersion (silica concentration 10% by mass) prepared by mixing silica and water were mixed and stirred to promote bonding (reaction) between the PNIPAM and the silica, thereby producing surface-treated silica 1 (adhesion amount of temperature-responsive compound 20 parts by mass per 100 parts by mass of silica). (Reaction conditions) Temperature: 25℃ Duration: 12 hours pH: 7.5

[0139] <Production Example 2-1 Synthesis of PNNPAM> An NNPAM polymer (PNNPAM) was synthesized in the same manner as in Production Example 1-1 above, except that Nn-propylacrylamide (NNPAM monomer) was used instead of N-isopropylacrylamide.

[0140] <Production Example 2-2: Production of Surface-Treated Silica 2> Surface-treated silica 2 (adhesion amount of temperature-responsive compound: 22 parts by mass per 100 parts by mass of silica) was prepared in the same manner as in Production Example 1-2 above, except that PNNPAM was used instead of PNIPAM.

[0141] <Examples and Comparative Examples> According to the compounding recipes shown in Tables 2 to 4, chemicals other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. To the kneaded mixture, sulfur and vulcanization accelerator were added, and the mixture was kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was press-vulcanized at 170° C. for 12 minutes to obtain a vulcanized rubber composition sheet having a thickness of 2 mm. In addition, the obtained unvulcanized rubber composition was molded to fit the shape of a cap tread, and then laminated together with other tire components to produce an unvulcanized tire. The tire was then vulcanized at 170°C for 15 minutes to obtain a test tire (size: 195 / 65R15).

[0142] The obtained vulcanized rubber compositions and test tires were stored in a dark place at room temperature for three months, and then the following evaluations were carried out. The results are shown in Tables 2, 3, and 4. The reference comparative examples in Tables 2, 3, and 4 are Comparative Examples 1-1, 2-1, and 3-1, respectively.

[0143] <Wear resistance> The abrasion loss of the vulcanized rubber composition was measured using a Lambourn abrasion tester manufactured by Iwamoto Seisakusho Co., Ltd., at a surface rotation speed of 50 m / min, an applied load of 3.0 kg, a sand drop rate of 15 g / min, and a slip ratio of 20%, and the reciprocal of each abrasion loss was calculated. The reciprocal of the abrasion loss of the reference comparative example was set to 100, and the reciprocals of the other abrasion losses were expressed as an index. A higher index indicates better abrasion resistance.

[0144] <Ice performance> Using the test tires, actual vehicle performance on snow and ice was evaluated under the following conditions (test conditions: ice temperature -2 to -6°C, snow temperature -3 to -10°C). The test tires were mounted on a domestically produced 2000cc FR vehicle, and the stopping distance on ice required to stop the vehicle by applying the lock brakes at 30 km / h was measured. The results were then indexed using the following formula, with the reference comparative example as the standard. A higher index indicates better on-ice performance. (Ice performance) = (braking stopping distance of standard comparison example) / (stopping distance) × 100

[0145] [Table 2]

[0146] [Table 3]

[0147] [Table 4]

[0148] The rubber composition of the example, obtained by mixing a rubber component with silica that had been surface-treated in advance to bond with a temperature-responsive compound, had a rubber surface that became hydrophilic at low temperatures, improving performance on ice. It was found that this composition could reversibly change tire performance in response to temperature changes.

[0149] Furthermore, in the Examples, the performance on ice was improved, and the overall performance of the performance on ice and abrasion resistance (expressed as the sum of the two indices of the performance on ice and abrasion resistance) was also excellent.

[0150] The present disclosure (1) is a rubber composition for tires obtained by mixing a rubber component with silica that has been surface-treated in advance to bond with a temperature-responsive compound.

[0151] The present disclosure (2) is the rubber composition for tires according to the present disclosure (1), which contains silica that has not been subjected to the surface treatment.

[0152] The present disclosure (3) includes styrene butadiene rubber, and The rubber composition for a tire according to the present disclosure (1) or (2) is one in which the styrene content (% by mass) and the vinyl content (% by mass) of the styrene-butadiene rubber satisfy the following formulas: Styrene content + vinyl content <50.0% by mass

[0153] The present disclosure (4) includes a styrene-butadiene rubber and an isoprene-based rubber and / or a butadiene rubber, and In the rubber composition for tires according to any one of the present disclosures (1) to (3), the content of the styrene-butadiene rubber and the total content of the isoprene-based rubber and butadiene rubber satisfy the following formula: Styrene butadiene rubber content > Total content of isoprene rubber and butadiene rubber > 0

[0154] The present disclosure (5) is the rubber composition for a tire according to any one of the present disclosures (1) to (4), in which the total amount of silica material and the content of the plasticizer satisfy the following formula: 3.5≦total amount of silica material / plasticizer content≦5.5

[0155] The present disclosure (6) is the rubber composition for a tire according to any one of the present disclosures (1) to (5), in which the total amount of silica material and the content of the liquid plasticizer satisfy the following formula: 3.5≦total amount of silica material / liquid plasticizer content≦5.5

[0156] The present disclosure (7) is a rubber composition for a tire according to any one of the present disclosures (1) to (6), in which the total amount of silica material and the total content of the liquid resin and the liquid diene-based polymer satisfy the following formula: 3.5≦Total amount of silica material / Total content of liquid resin and liquid diene polymer≦7.0

[0157] The present disclosure (8) is a rubber composition for a tire according to any one of the present disclosures (1) to (7), in which the total amount of silica material and the content of resin satisfy the following formula: 7.0≦Total amount of silica material / Resin content≦16.0

[0158] The present disclosure (9) is the rubber composition for a tire according to any one of the present disclosures (1) to (8), wherein the total amount of the silica material exceeds 50 parts by mass per 100 parts by mass of the rubber component.

[0159] The present disclosure (10) is a tire having a tread made of the rubber composition according to any one of the present disclosures (1) to (9).

[0160] The present disclosure (11) is the tire according to the present disclosure (10), which is an all-season tire.

Claims

1. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, The rubber component contains a styrene-butadiene rubber and an isoprene-based rubber and / or a butadiene rubber, and A rubber composition for tires, wherein the styrene content (mass%) and vinyl content (mass%) of the styrene-butadiene rubber satisfy the following formulas: Styrene content + vinyl content < 50.0 mass%

2. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, The rubber component contains a styrene-butadiene rubber and an isoprene-based rubber and / or a butadiene rubber, and The rubber composition for tires has a content of the styrene-butadiene rubber and a total content of the isoprene-based rubber and butadiene rubber that satisfy the following formula: Styrene butadiene rubber content > Total content of isoprene rubber and butadiene rubber > 0

3. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, the rubber component contains a styrene-butadiene rubber, and an isoprene-based rubber and / or a butadiene rubber, A rubber composition for tires, in which the total amount of silica material and the content of plasticizer satisfy the following formula: 3.5≦total amount of silica material / plasticizer content≦5.5

4. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, the rubber component contains a styrene-butadiene rubber, and an isoprene-based rubber and / or a butadiene rubber, A rubber composition for tires, wherein the total amount of silica material and the content of liquid plasticizer satisfy the following formula: 3.5≦total amount of silica material / content of liquid plasticizer≦5.5

5. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, the rubber component contains a styrene-butadiene rubber, and an isoprene-based rubber and / or a butadiene rubber, A rubber composition for tires, in which the total amount of silica material and the total content of liquid resin and liquid diene-based polymer satisfy the following formula: 3.5≦total amount of silica material / total content of liquid resin and liquid diene-based polymer≦7.0

6. The rubber composition is obtained by mixing a rubber component with silica that has been surface-treated in advance to be bonded with a temperature-responsive polymer having a lower critical solution temperature of −20° C. or more and 35° C. or less, the rubber component contains a styrene-butadiene rubber, and an isoprene-based rubber and / or a butadiene rubber, A rubber composition for tires, in which the total amount of silica material and the content of resin satisfy the following formula: 7.0≦total amount of silica material / resin content≦16.0

7. 7. The rubber composition for a tire according to claim 1, further comprising silica that has not been subjected to a surface treatment.

8. The rubber composition for a tire according to any one of claims 1 to 7, wherein the total amount of the silica material per 100 parts by mass of the rubber component exceeds 50 parts by mass.

9. A tire having a tread made of the rubber composition according to any one of claims 1 to 8.

10. 10. The tire of claim 9, which is an all-season tire.

Images