Polymer composite, rubber composition and tire

Abstract

Provided are a polymer composite, a rubber composition, and a tire with which it is possible to reversibly change tire performance in response to temperature changes. The present invention relates to a polymer composite comprising a conjugated diene polymer having a weight-average molecular weight, as determined by gel permeation chromatography, of 100,000 or higher, the polymer composite having a temperature dependency of contact angle with water which, at two temperatures differing by 10°C or more, reversibly satisfies the following relationship (II). Relationship (II): Temperature dependency of contact angle = Lower-temperature contact angle / Higher-temperature contact angle × 100 ≤ 90

Description

[Technical Field]

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

[0002] BACKGROUND ART Tires have traditionally been required to have various performance characteristics (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-214377 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the tire industry has not paid much attention to changing tire performance in response to temperature changes, and conventional technology leaves room for improvement in terms of changing tire performance in response to temperature changes. In particular, the surface characteristics of tires depend on the environment. For example, in sunny weather (relatively high temperatures), a hydrophobic surface is required to improve dry grip performance, and in rainy weather (relatively low temperatures), a more hydrophilic surface is required to improve wet grip performance. In conventional rubber compositions, the surface properties (contact angle with water) depend on the compounding, so in order to impart temperature-dependent changes in surface properties through compounding, one possible method is to compound a temperature-responsive material such as poly(N-isopropylacrylamide) (PNIPAM).However, because these materials are soluble in water, they dissolve and disappear from the composition in the event of rain, making it impossible to impart reversible changes in surface properties. An object of the present invention is to solve the above problems and to provide a polymer composite, a rubber composition, and a tire that are capable of reversibly changing tire performance in response to temperature changes. [Means for solving the problem]

[0005] The present invention is formed from a conjugated diene polymer having a weight average molecular weight of 100,000 or more as measured by gel permeation chromatography, At two temperatures that are 10°C or more apart, The polymer composite has a temperature dependence of the water contact angle that reversibly satisfies the following formula (II): Equation (II) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90

[0006] The polymer composite preferably has a group whose hydrophilicity changes with temperature.

[0007] The above group is preferably a group that exhibits a lower critical solution temperature in water.

[0008] Preferably, the group is a poly(N-substituted (meth)acrylamide).

[0009] The above group is preferably a group represented by the following formula (I): [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

[0010] Preferably, the group is poly(N-isopropylacrylamide).

[0011] The conjugated diene polymer is preferably an isoprene-based rubber.

[0012] The conjugated diene polymer is preferably a butadiene rubber.

[0013] The conjugated diene polymer is preferably a styrene-butadiene rubber.

[0014] The left side of formula (II) is preferably 88 or less, and more preferably 85 or less.

[0015] The polymer composite comprises a conjugated diene polymer having a weight average molecular weight of 100,000 or more as measured by gel permeation chromatography, and A radical generator; a reactant having one or more heteroatoms and one or more carbon-carbon double bonds; in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents, It is preferable that the mixture be formed by stirring at a temperature of 40°C or higher and 200°C or lower.

[0016] In the polymer composite, it is preferable that the residual ratio of the reactants before and after stirring satisfies the following formula (III). Formula (III) Remaining rate of reactant: Reactant peak intensity before stirring / (Reactant peak intensity before stirring+Reactant peak intensity after stirring)×100≦50

[0017] In the polymer composite, it is preferable that the residual rate of the conjugated diene unit in the conjugated diene polymer before and after stirring satisfies the following formula (IV). Formula (IV) Residual rate of conjugated diene: double bond peak intensity derived from conjugated diene before stirring / (double bond peak intensity derived from conjugated diene before stirring+double bond peak intensity derived from conjugated diene after stirring)×100≦99

[0018] The present invention also relates to a rubber composition containing the above polymer composite.

[0019] The composition is preferably for use in a tire tread.

[0020] The present invention also relates to a tire having tire components using the above composition.

[0021] The tire component is preferably a tread.

[0022] The present invention also relates to a rubber composition in which the temperature dependency of the water contact angle reversibly satisfies the following formula (I) at two temperatures that are 10° C. or more apart. Formula (I) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90

[0023] The composition preferably contains the polymer composite.

[0024] The composition has a nitrogen adsorption specific surface area of 145 m 2 It is preferable that the carbon black contains at least 100% carbon black.

[0025] The composition is preferably for use in a tire tread.

[0026] The present invention also relates to a tire having tire components using the above composition.

[0027] The tire component is preferably a tread. [Effects of the Invention]

[0028] According to the present invention, the polymer composite is formed from a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, and the temperature dependency of the water contact angle reversibly satisfies the above formula (II) at two temperatures that are 10°C or more apart. Therefore, the tire performance can be reversibly changed in response to temperature changes.

[0029] Furthermore, according to the present invention, the rubber composition has a temperature dependency of the water contact angle that reversibly satisfies the above formula (I) at two temperatures that are 10°C or more apart, and therefore tire performance can be reversibly changed in response to temperature changes. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a graph showing the temperature dependence of the contact angle of the polymer composites of Example 2 and Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0031] (polymer composite) The polymer composite of the present invention is formed from a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, and is a polymer composite in which the temperature dependence of the water contact angle reversibly satisfies the following formula (II) at two temperatures that are 10°C or more apart. This makes it possible to reversibly change tire performance in response to temperature changes. The polymer composite is formed from a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, and A radical generator; a reactant having one or more heteroatoms and one or more carbon-carbon double bonds; in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents, It is preferable that the mixture be formed by stirring at a temperature of 40°C or higher and 200°C or lower. Equation (II) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90

[0032] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. The polymer composite of the present invention is a polymer composite formed from a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, and is formed, for example, by stirring a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, a radical generator, and a reactant having one or more heteroatoms and one or more carbon-carbon double bonds in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents at a temperature of 40° C. to 200° C. That is, the polymer composite of the present invention is formed, for example, by reacting the conjugated diene polymer with a reactant having one or more heteroatoms and one or more carbon-carbon double bonds, and more specifically, for example, is a polymer composite in which a group formed by a reactant having one or more heteroatoms and one or more carbon-carbon double bonds is bonded to the conjugated diene polymer. The reactant is a compound having one or more heteroatoms and one or more carbon-carbon double bonds. Because the reactant has one or more carbon-carbon double bonds, it can undergo radical polymerization and further radical addition to the conjugated diene polymer. That is, the reactant exhibits radical reactivity with a radical generator due to the generated radicals. Furthermore, because the reactant has one or more heteroatoms, it can form a group whose hydrophilicity changes with temperature. That is, the polymer composite of the present invention is preferably a polymer composite in which a group whose hydrophilicity changes with temperature is bonded to the conjugated diene polymer. Such a polymer composite in which a group whose hydrophilicity changes with temperature is bonded to the conjugated diene polymer has a group whose hydrophilicity changes with temperature, and therefore the hydrophilicity changes with temperature, so that the temperature dependence of the water contact angle reversibly satisfies the above formula (II) at two temperatures that are 10°C or more apart. Satisfying the above formula (II) means that the hydrophilicity changes with temperature, and the change in hydrophilicity with temperature changes changes the compatibility with other components in the composition, making it possible to change tire performance in response to temperature changes. Furthermore, in the polymer composite of the present invention, a group whose hydrophilicity changes with temperature is bonded to the conjugated diene polymer. This prevents the group whose hydrophilicity changes with temperature from dissolving in water and flowing out, and therefore makes it possible to reversibly change tire performance in response to temperature changes. As described above, the present invention solves the problem (objective) of reversibly changing tire performance in response to temperature changes by configuring a polymer composite that satisfies the parameters of formula (II) above. In other words, the parameters do not define the problem (objective); the object of the present application is to reversibly change tire performance in response to temperature changes, and as a means of achieving this, the polymer composite is configured to satisfy the parameters of formula (II) above. In other words, satisfying the parameters of formula (II) above is an essential constituent requirement. However, simply mixing the conjugated diene polymer with a group whose hydrophilicity changes with temperature (temperature-responsive polymer) does not result in the polymer composite of the present invention, because the group whose hydrophilicity changes with temperature is not bonded to the conjugated diene polymer. Furthermore, if the temperature-responsive polymer is blended alone into a rubber composition rather than the polymer composite, the temperature-responsive polymer will dissolve in water and flow out of the rubber composition, making it impossible to reversibly change tire performance in response to temperature changes.

[0033] In this specification, "the temperature dependence of the water contact angle reversibly satisfies the above formula (II) at two temperatures that are 10°C or more apart" means that, even after repeated temperature changes or contact with water, the temperature dependence of the water contact angle satisfies the above formula (II) at two temperatures that are 10°C or more apart. Similarly, in this specification, "the temperature dependence of the water contact angle reversibly satisfies the above formula (I) at two temperatures that are 10°C or more apart" means that, even after repeated temperature changes or contact with water, the temperature dependence of the water contact angle satisfies the above formula (I) at two temperatures that are 10°C or more apart. In this specification, the unit of contact angle is ° unless otherwise specified.

[0034] <Groups whose hydrophilicity changes with temperature> First, groups whose hydrophilicity changes with temperature will be described below. In this specification, the group whose hydrophilicity changes with temperature may be any group whose hydrophilicity changes with temperature, and is preferably a group whose hydrophilicity changes reversibly with temperature.

[0035] Examples of groups whose hydrophilicity changes reversibly with temperature include temperature-responsive polymers (temperature-responsive polymer groups). That is, a polymer composite having a group whose hydrophilicity changes reversibly with temperature means, for example, a polymer composite having a group formed by a temperature-responsive polymer. Examples of the polymer composite include a polymer composite to which a temperature-responsive polymer is grafted, a polymer composite having a temperature-responsive polymer unit in the main chain, and a polymer composite having a temperature-responsive polymer block in the main chain. These may be used alone or in combination of two or more.

[0036] Thermoresponsive polymers are materials that undergo reversible conformational changes in polymer chains associated with hydration and dehydration in response to temperature changes in water, resulting in reversible changes in hydrophilicity and hydrophobicity with temperature changes. This reversible change is known to be due to the molecular structure that contains hydrophilic groups capable of hydrogen bonding and hydrophobic groups that are incompatible with water within a single molecule. The present inventors have found that the hydrophilicity and hydrophobicity of temperature-responsive polymers change reversibly with temperature not only in water but also in rubber compositions. Furthermore, they have found that the hydrophilicity and hydrophobicity of polymer composites in which a group (temperature-responsive polymer group) whose hydrophilicity changes with temperature is bonded to the above-mentioned conjugated diene polymer also change reversibly with temperature in rubber compositions.

[0037] 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.

[0038] 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.

[0039] If the group whose hydrophilicity changes reversibly with a change in temperature is a polymer that exhibits LCST, the glass transition temperature changes as the polymer becomes incompatible with other components in the composition due to a change in temperature, and tire performance (e.g., wet grip performance, ice grip performance) can be changed in response to temperature changes. In the polymer composite, the group whose hydrophilicity changes reversibly with temperature is preferably a polymer that exhibits LCST, i.e., the group whose hydrophilicity changes with temperature is preferably a group that exhibits a lower critical solution temperature in water. In this specification, a group that exhibits a lower critical solution temperature (LCST) in water means a group that exhibits a lower critical solution temperature in water when a group contained in a polymer composite is cleaved from the polymer composite and the cleaved group (polymer) is placed in water. Similarly, in this specification, a group that exhibits an upper critical solution temperature (UCST) in water means a group that exhibits an upper critical solution temperature in water when a group contained in a polymer composite is cleaved from the polymer composite and the cleaved group (polymer) is placed in water.

[0040] The group (polymer) exhibiting LCST will be explained below. The group (polymer) exhibiting LCST may be used alone or in combination of two or more kinds. The group (polymer) exhibiting LCST is not particularly limited as long as it is a group (polymer) exhibiting LCST, but poly(N-substituted (meth)acrylamide) is preferred, and among poly(N-substituted (meth)acrylamide), a group represented by the following formula (I) is 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

[0041] 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.

[0042] R 1 and R 2The 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.

[0043] R 1 and R 2 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.

[0044] 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.

[0045] R 1 and R 2 The hydrocarbyl group may be branched or unbranched, but is preferably branched.

[0046] 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]

[0047] 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.

[0048] R 3 The hydrocarbyl group in R 1 and R 2 Among these, alkyl groups are preferred.

[0049] R 3 The hydrocarbyl groups may be branched or unbranched.

[0050] R 3 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom.

[0051] Examples of the group 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), poly(N,N-diethylacrylamide), poly(Nn-propylacrylamide), and poly(N-isopropyl,N-methylacrylamide) are preferred, and poly(N-isopropylacrylamide) (PNIPAM) is more preferred.

[0052] 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. Polymer composites containing PNIPAM groups undergo a significant change in their hydrophilic / hydrophobic surface properties at approximately 32°C. Therefore, by using them as polymer composites for rubber compositions, tire performance can be reversibly changed in response to temperature changes.

[0053] Examples of groups (polymers) exhibiting LCST other than the group represented by the above formula (I) 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 is 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-tetrahydrofurfuryl methyl cellulose), and the like. 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 the compound of formula (A)), ethoxylated iso-C13 H 27 Examples 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.)

[0054] The weight-average molecular weight of the group whose hydrophilicity changes with temperature (the group formed by 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.

[0055] The phase transition temperature (lower critical solution temperature (LCST) or upper critical solution temperature (UCST)) of the temperature-responsive polymer is preferably 5°C or higher, more preferably 15°C or higher, even more preferably 20°C or higher, and particularly preferably 25°C or higher, and is preferably 60°C or lower, more preferably 50°C or lower, even more preferably 40°C or lower, and particularly preferably 35°C or lower. Within the above ranges, 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%. Here, the temperature-responsive polymer refers to a temperature-responsive polymer group (temperature-responsive polymer) obtained by cleaving a temperature-responsive polymer group contained in a polymer composite from the polymer composite.

[0056] <Method of manufacturing polymer composite> The polymer composite is formed from a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, and is preferably formed by stirring a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, a radical generator, and a reactant having one or more heteroatoms and one or more carbon-carbon double bonds in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents at a temperature of 40°C to 200°C.

[0057] The polymer composite may be produced using known synthesis techniques, for example, by referring to JP-A-2005-314419, JP-A-2016-505679, JP-A-2015-531672, JP-A-2003-252936, JP-A-2004-307523, etc.

[0058] <<Conjugated diene polymer>> The conjugated diene polymer has a weight average molecular weight (Mw) measured by gel permeation chromatography of 100,000 or more, preferably 200,000 or more, more preferably 300,000 or more, and although there is no particular upper limit, it is preferably 4,000,000 or less, more preferably 3,000,000 or less, even more preferably 2,000,000 or less, and particularly preferably 1,200,000 or less. Within the above ranges, better effects tend to be obtained. In this specification, Mw and number average molecular weight (Mn) can be determined in terms of standard polystyrene based on measurements 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).

[0059] The conjugated diene polymer is not particularly limited, and examples thereof include diene rubbers commonly used as rubber components in tire compositions, such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and butyl rubber (IIR). These may be used alone or in combination of two or more. Among these, isoprene rubber, BR, and SBR are preferred, with BR and SBR being more preferred. The conjugated diene polymer may be a commercially available product, or may be one polymerized by a known method.

[0060] The diene rubber may be an unmodified polymer or a modified polymer. The modified polymer may be a polymer (preferably a diene rubber) having a functional group that interacts with a filler such as silica. Examples include terminally modified polymers (terminally modified polymers having the functional group at the terminal) in which at least one terminal of the polymer has been modified with a compound (modifier) having the functional group, main chain modified polymers having the functional group in the main chain, main chain terminally modified polymers having the functional group in the main chain and at least one terminal (for example, main chain terminally modified polymers having the functional group in the main chain and at least one terminal modified with the modifier), and terminally modified polymers 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.

[0061] 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. These may be used alone or in combination of two or more. Among these, 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.

[0062] 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.

[0063] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% 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.

[0064] 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.

[0065] The SBR may be unmodified or modified. Modified SBR includes modified SBR into which the same functional groups as those in the modified polymer have been introduced. Of these, unmodified SBR is preferred.

[0066] The BR is not particularly limited, and examples thereof include high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). These may be used alone or in combination of two or more. Among these, rare earth BR is preferred.

[0067] The cis content of BR is preferably 90% by mass or more, more preferably 95% by mass or more, with no particular upper limit. Within the above range, better effects tend to be obtained. The cis content can be measured by infrared absorption spectroscopy.

[0068] The BR may be either unmodified or modified. Examples of modified BR include modified BRs into which the same functional groups as those in modified polymers have been introduced. Among these, unmodified BRs are preferred.

[0069] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0070] 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 are commonly used in the tire industry. IRs are not particularly limited, and examples of IRs such as IR2200 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. NR is preferred.

[0071] <<Radical generator>> The radical generator is not particularly limited, but examples thereof include azo compounds, organic oxides, dihalogens, redox initiators, etc., which are generally used as radical initiators. These may be used alone or in combination of two or more.

[0072] The azo compound is not particularly limited as long as it is a compound having an azo bond, but examples thereof include azobisisobutyronitrile (AIBN), azodicarbonamide, 2,2'-azobis-(2-amidinopropane) dihydrochloride, dimethyl 2,2'-azobis(isobutyrate), azobis-cyanovaleric acid, 1,1'-azobis-(2,4-dimethylvaleronitrile), azobismethylbutyronitrile, and 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile). These may be used alone or in combination of two or more. Among these, azobisisobutyronitrile (AIBN) is preferred.

[0073] The organic oxide is not particularly limited, but examples thereof include di-tert-butyl peroxide, tert-butyl hydroperoxide, paramenthane hydroperoxide, diisopropylbenzene hydroperoxide, diisopropylbenzene hydroperoxide, acetylcyclohexanesulfonyl peroxide, diisopropyl purged carbonate, di-sec-butyl purged carbonate, benzoyl peroxide, lauroyl peroxide, etc., and examples of azo compounds include azobisisobutyronitrile, azobismethoxydimethylvaleronitrile, azobisdimethylvaleronitrile, azobisaminopropane hydrochloride, etc. These may be used alone or in combination of two or more.

[0074] The dihalogen is not particularly limited, but examples thereof include chlorine, bromine, iodine, etc. These may be used alone or in combination of two or more.

[0075] The redox initiator is not particularly limited as long as it is a combination of a peroxide and a reducing agent, and examples thereof include a combination of hydrogen peroxide and an iron (II) salt, a combination of a peroxide salt such as potassium peroxodisulfate and sodium hydrogen sulfite, etc. These may be used alone or in combination of two or more.

[0076] Among these, the radical generator is preferably an azo compound, and more preferably azobisisobutyronitrile (AIBN).

[0077] <<Reactants containing one or more heteroatoms and one or more carbon-carbon double bonds>> The reactant having one or more heteroatoms and one or more carbon-carbon double bonds is not particularly limited as long as it has one or more heteroatoms and one or more carbon-carbon double bonds. These may be used alone or in combination of two or more.

[0078] The heteroatom is not particularly limited, and examples thereof include an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, etc. Among these, the reactant preferably has an oxygen atom and a nitrogen atom, and more preferably has one oxygen atom and one nitrogen atom. The number of carbon-carbon double bonds contained in the reactant is not particularly limited, but it is preferable that the number is one.

[0079] Specifically, the reactant is not particularly limited as long as it is a compound capable of forming the above-mentioned group whose hydrophilicity changes with temperature change (temperature-responsive polymer (temperature-responsive polymer group)), and is preferably a compound capable of forming the above-mentioned group whose hydrophilicity changes with temperature change (temperature-responsive polymer (temperature-responsive polymer group)) by radical polymerization. Since temperature-responsive polymers are characterized by containing both hydrophobic and hydrophilic groups in their structure, compounds (monomers) capable of forming temperature-responsive polymers necessarily contain one or more types of heteroatoms. The reactant is preferably a compound capable of forming a group that exhibits a lower critical solution temperature in water, more preferably a compound capable of forming poly(N-substituted (meth)acrylamide), still more preferably a compound capable of forming a group represented by formula (I) above, and particularly preferably a compound capable of forming poly(N-isopropylacrylamide). For example, to produce a polymer composite containing PNIPAM, isopropylacrylamide (NIPAM), a monomer that constitutes PNIPAM, may be used as the reactant.

[0080] More specifically, the reactants include alkylacrylamides such as isopropylacrylamide (NIPAM) and ethylacrylamide, which are monomers constituting PNIPAM, n-propylacrylamide (NNPAM) and ethylmethylacrylamide, which are monomers constituting PNNPAM, diethylacrylamide (NDEAM), which is a monomer constituting PNDEAM, isopropylmethylacrylamide (NMNIPAM), which is a monomer constituting PNMNIPAM, cyclopropylacrylamide, acryloylpyrrolidine, and acryloylpiperidine; Alkyl methacrylamides such as isopropyl methacrylamide, ethyl methacrylamide, n-propyl methacrylamide, ethyl methyl methacrylamide, diethyl methacrylamide, isopropyl methyl methacrylamide, cyclopropyl methacrylamide, methacryloylpyrrolidine, and methacryloylpiperidine; Examples of suitable monomers include vinyl caprolactam, 2-alkyl-2-oxazoline, ethoxyethyl acrylamide, ethoxyethyl methacrylamide, tetrahydrofurfuryl acrylamide, tetrahydrofurfuryl methacrylamide, vinyl methyl ether, 2-(dimethylamino)ethyl methacrylate, 3-ethyl-N-vinyl-2-pyrrolidone, and epoxide-allyl glycidyl ether copolymers. These may be used alone or in combination. Among these, alkyl acrylamides are preferred, with isopropyl acrylamide (NIPAM), n-propyl acrylamide (NNPAM), diethyl acrylamide (NDEAM), and isopropyl methyl acrylamide (NMNIPAM) being more preferred, and isopropyl acrylamide (NIPAM) being even more preferred.

[0081] <<Solvent>> The solvent is not particularly limited, but at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents may be used. These may be used alone or in combination of two or more. The solvent is appropriately selected according to the radical generation temperature of the radical generator used.

[0082] The hydrocarbon solvent is not particularly limited, but examples thereof include linear hydrocarbon solvents such as pentane, hexane, heptane, and octane; cyclic hydrocarbon solvents such as cyclohexane and terpene solvents; etc. These may be used alone or in combination of two or more.

[0083] The aromatic solvent is not particularly limited, but examples thereof include aromatic hydrocarbon solvents such as benzene, toluene, ethylbenzene, and xylene; heterocyclic aromatic solvents such as pyridine; etc. These may be used alone or in combination of two or more.

[0084] The aprotic polar solvent is not particularly limited, but examples thereof include diethyl ether, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, etc. These may be used alone or in combination of two or more.

[0085] The solvent is preferably a hydrocarbon solvent, more preferably a straight-chain hydrocarbon solvent or a cyclic hydrocarbon solvent, and further preferably hexane or cyclohexane. Additionally, aprotic polar solvents are also preferred, with tetrahydrofuran being more preferred.

[0086] <<Mixing>> The polymer composite is formed by stirring the conjugated diene polymer, the radical generator, and the reactant in a solvent at a temperature of 40°C or higher and 200°C or lower.

[0087] The temperature during stirring is preferably 40°C or higher and 200°C or lower. If the temperature is 40°C or higher, the reaction tends to proceed sufficiently, and if the temperature is 200°C or lower, decomposition of the conjugated diene polymer tends to be suppressed. The lower limit is more preferably 50°C or higher, and even more preferably 60°C or higher, and the upper limit is more preferably 180°C or lower, even more preferably 160°C or lower, particularly preferably 140°C or lower, and most preferably 120°C or lower. Within the above range, the effect tends to be more favorably obtained.

[0088] The stirring method and stirring speed are not particularly limited as long as the components in the solvent are mixed together.

[0089] The stirring time (reaction time) is not particularly limited, but is preferably 0.5 hours or more, more preferably 1 hour or more, even more preferably 2 hours or more, and particularly preferably 4 hours or more, and the upper limit is not particularly limited, but is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less. Within the above range, the effect tends to be better.

[0090] The amounts of the conjugated diene polymer, radical generator, reactant, and solvent used when producing the polymer composite are not particularly limited, but are preferably as follows: Within the following ranges, better effects tend to be obtained. The amount of the reactant used is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 200 parts by mass or less, more preferably 120 parts by mass or less, per 100 parts by mass of the conjugated diene polymer. The amount of the radical generator used is preferably 0.001 mol or more, more preferably 0.01 mol or more, and preferably 1.0 mol or less, more preferably 0.1 mol or less, per 100 mol of the reactants. The amount of the solvent used is not particularly limited as long as the conjugated diene polymer, the radical generator, and the reactants can be mixed sufficiently, but is, for example, about 18 times the amount (mL / g) of the amount of the monomer used.

[0091] It is preferable that the residual rate of the reactants before and after stirring satisfies the following formula (III), which ensures that the reaction rate of the reactants is high and that the reactants are reacting during stirring, and tends to produce better effects. Formula (III) Remaining rate of reactant: Reactant peak intensity before stirring / (Reactant peak intensity before stirring+Reactant peak intensity after stirring)×100≦50

[0092] The left side of formula (III) is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less, and although there is no particular lower limit, it is preferably 0.01 or more, more preferably 0.1 or more, and even more preferably 0.5 or more. Within the above range, the reaction rate of the reactants is high, and the effect tends to be more favorable. In this specification, the left side of formula (III) is measured by the method described in the Examples.

[0093] It is preferable that the residual rate of the conjugated diene unit in the conjugated diene polymer before and after stirring satisfies the following formula (IV), which confirms that the radicals derived from the reactants have sufficiently reacted with the conjugated diene polymer, and tends to produce a better effect. Formula (IV) Residual rate of conjugated diene: double bond peak intensity derived from conjugated diene before stirring / (double bond peak intensity derived from conjugated diene before stirring+double bond peak intensity derived from conjugated diene after stirring)×100≦99

[0094] The left side of formula (IV) is preferably 99 or less, more preferably 98 or less, and even more preferably 97 or less, and although there is no particular lower limit, it is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 10 or more, particularly preferably 50 or more, and most preferably 80 or more. Within the above range, the reaction rate of the reactants is high, and the effect tends to be more favorable. In this specification, the left side of formula (IV) is measured by the method described in the Examples.

[0095] The terminals of the temperature-responsive polymer (for example, the groups represented by formulae (I) to (IV)) will be described. In the case of a polymer composite to which a temperature-responsive polymer is grafted, one end of the temperature-responsive polymer is the main chain or a bond to the main chain, and the other end is usually a hydrogen atom, but may also be bonded to a radical generator such as azobisisobutyronitrile (AIBN).

[0096] The polymer composite obtained by the above-mentioned production method reversibly satisfies the following formula (II) in terms of the temperature dependency of the water contact angle at two temperatures that are 10° C. or more apart. Equation (II) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90 In this specification, the contact angle of the polymer composite with water is measured by the method described in the Examples.

[0097] The two temperatures that are 10°C or more apart are not particularly limited as long as they fall within the range of tire operating temperatures, preferably within the range of -80°C to 80°C, with the lower limit of the temperature range more preferably being -50°C or higher, and even more preferably being -20°C or higher, and the upper limit of the temperature range more preferably being 80°C or lower, and even more preferably being 50°C or lower. The two temperatures are determined by the chemical structure of the temperature-responsive polymer. This is because the critical solution temperature of a temperature-responsive polymer is determined by the chemical structure of the temperature-responsive polymer. For example, the two temperatures with a difference of 10°C or more may be 20°C and 40°C.

[0098] The left side of formula (II) is 90 or less. Typically, the contact angle of water for a conjugated diene polymer remains constant at 90° or greater regardless of temperature, demonstrating hydrophobicity. On the other hand, the contact angle for the polymer composite described above decreases by more than 90% at temperatures 10°C or more lower than a certain temperature at which the polymer composite exhibits hydrophobicity, demonstrating greater hydrophilicity. The left side of formula (II) is preferably 88 or less, more preferably 85 or less, even more preferably 80 or less, particularly preferably 78 or less, most preferably 77 or less, more preferably 76 or less, more preferably 74 or less, more preferably 72 or less, more preferably 71 or less, more preferably 70 or less, more preferably 68 or less, more preferably 66 or less, and although there is no particular lower limit, it is preferably 5 or more, more preferably 10 or more, even more preferably 30 or more, particularly preferably 50 or more, and most preferably 64 or more. Within the above ranges, better effects tend to be obtained.

[0099] In the above polymer composite, the contact angle (°) with water at 20°C is preferably 90 or less, more preferably 89 or less, even more preferably 88 or less, particularly preferably 80 or less, most preferably 78 or less, more preferably 76 or less, more preferably 74 or less, more preferably 73 or less, more preferably 72 or less, more preferably 71 or less, more preferably 70 or less, more preferably 68 or less, more preferably 65 or less, more preferably 64 or less, and although there is no particular lower limit, it is preferably 10 or more, more preferably 30 or more, even more preferably 40 or more, particularly preferably 50 or more, and most preferably 62 or more. When it is within the above range, better effects tend to be obtained.

[0100] As is clear from the above explanation, the left side of formula (II), the contact angle of the polymer composite with water at 20°C, can be adjusted appropriately by changing the type and content of the group (temperature-responsive polymer) whose hydrophilicity changes with temperature, which the polymer composite has. For example, by increasing the content of the group (temperature-responsive polymer) whose hydrophilicity changes with temperature, the left side of formula (II), the contact angle of water at 20°C, tends to decrease.

[0101] As is clear from the above explanation, the polymer composite preferably has a group whose hydrophilicity changes with temperature, more preferably has a group that exhibits a lower critical solution temperature in water, further preferably has a poly(N-substituted (meth)acrylamide) group, particularly preferably has a group represented by the above formula (I), and most preferably has a poly(N-isopropylacrylamide) group.

[0102] The content of groups whose hydrophilicity changes with temperature (groups formed by reactants) in the polymer composite (100% by mass) is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 7% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less. When the content is within the above range, better effects tend to be obtained.

[0103] The content of the conjugated diene polymer in 100% by mass of the polymer composite is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 93% by mass or less. When it is within the above range, better effects tend to be obtained.

[0104] The total content of the temperature-dependent hydrophilicity-changing group (the group formed by the reactant) and the conjugated diene polymer in the polymer composite (100% by mass) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 98% by mass or more, and may be 100% by mass. When it is within the above range, better effects tend to be obtained. The content of the group (group formed by the reactant) whose hydrophilicity changes depending on the temperature in the polymer composite and the content of the conjugated diene polymer are measured by NMR.

[0105] The polymer composite can be used as a rubber component for a rubber composition.

[0106] (Rubber composition 1) The rubber composition 1 contains the above polymer composite. The above polymer composites may be used alone or in combination of two or more kinds. Since the polymer composite contains the conjugated diene polymer, only the conjugated diene polymer contained in the polymer composite may be used as the rubber component, or other rubber components may be used together with the conjugated diene polymer contained in the polymer composite. Examples of other rubber components include the diene rubbers described above, which may be used alone or in combination of two or more. As other rubber components, those explained above for the conjugated diene polymer can be used in the same preferred manner.

[0107] In the rubber composition, the content of the polymer composite is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 8 parts by mass or more, per 100 parts by mass of the rubber component, 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, particularly preferably 140 parts by mass or less, and most preferably 120 parts by mass or less. When the content is within the above range, better effects tend to be obtained.

[0108] The content of SBR in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and may be 100% by mass, but is preferably 90% by mass or less. When it is within the above range, better effects tend to be obtained.

[0109] The content of BR in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and may be 100% by mass, but is preferably 90% by mass or less. When it is within the above range, the effect tends to be more favorably obtained.

[0110] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and may be 100% by mass, but is preferably 90% by mass or less. When it is within the above range, the effect tends to be more favorably obtained.

[0111] The rubber composition preferably contains silica as a filler (reinforcing filler). The silica 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 them, wet process silica is preferred because it has a large number of silanol groups.

[0112] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0113] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 80m 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 200m 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.

[0114] The amount of silica per 100 parts by mass of the rubber component is preferably at least 0.1 part by mass, more preferably at least 5 parts by mass, even more preferably at least 10 parts by mass, and particularly preferably at least 20 parts by mass, and is preferably at most 200 parts by mass, more preferably at most 180 parts by mass, even more preferably at most 150 parts by mass, particularly preferably at most 120 parts by mass, and most preferably at most 100 parts by mass. Within the above ranges, the effect tends to be better obtained.

[0115] When silica is compounded into the rubber composition, it is preferable that a silane coupling agent is contained together with the silica. 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. Of these, sulfide-based silane coupling agents are preferred.

[0116] 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.

[0117] When containing silane coupling agent, the content of silane coupling agent is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, based on 100 parts by mass of silica.Furthermore, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.When it is within the above range, the effect tends to be more excellent.

[0118] The rubber composition preferably contains carbon black.

[0119] Examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more.

[0120] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 5 m 2 / g or more, more preferably 30m 2 / g or more, more preferably 60m 2 / g or more, particularly preferably 90m 2 / g or more, most preferably 120m 2 / g or more, more preferably 130m 2 / g or more, and most preferably 140m 2 / g or more, and most preferably 145m 2 / g or more. In addition, the N2SA is preferably 300m 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 nitrogen adsorption specific surface area of carbon black can be determined according to JIS K6217-2:2001.

[0121] The dibutyl phthalate oil absorption (DBP) of the carbon black is preferably 5 ml / 100 g or more, more preferably 70 ml / 100 g or more, and even more preferably 90 ml / 100 g or more. The DBP is preferably 300 ml / 100 g or less, more preferably 200 ml / 100 g or less, even more preferably 160 ml / 100 g or less, and particularly preferably 140 ml / 100 g or less. Within the above ranges, better effects tend to be obtained. The DBP of carbon black can be measured in accordance with JIS-K6217-4:2001.

[0122] As carbon black, for example, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Company, etc. can be used.

[0123] The amount of carbon black per 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, and 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, particularly preferably 80 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0124] 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.

[0125] 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.

[0126] 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 1 part by mass or more, per 100 parts by mass of the rubber component. The content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0127] The rubber composition preferably contains 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), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolyl sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene Examples of suitable vulcanization accelerators include sulfenamide-based vulcanization accelerators such as N,N'-diisopropyl-2-benzothiazolesulfenamide and N,N'-diisopropyl-2-benzothiazolesulfenamide; guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine; thiourea-based vulcanization accelerators; dithiocarbamic acid-based vulcanization accelerators; aldehyde-amine-based or aldehyde-ammonia-based vulcanization accelerators; imidazoline-based vulcanization accelerators; and xanthate-based vulcanization accelerators. These may be used alone or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred.

[0128] 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.

[0129] The content of the vulcanization accelerator is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component. The content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0130] 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.

[0131] The amount of stearic acid is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component. The amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0132] 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.

[0133] The amount of zinc oxide per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more. The amount is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0134] 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.

[0135] 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.

[0136] The content of the antioxidant is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component. The content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above ranges, the effect tends to be more favorable.

[0137] 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.

[0138] 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.

[0139] The wax content is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the rubber component. The wax content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less. Within the above ranges, the effect tends to be better.

[0140] The rubber composition may contain a plasticizer. In this specification, the term "plasticizer" refers to a material that imparts plasticity to rubber, and is a concept that includes liquid plasticizers (plasticizers that are liquid (liquid) at 25°C) and solid plasticizers (plasticizers that are solid at 25°C). Specifically, it is a component that can be extracted from a composition using acetone. These may be used alone or in combination of two or more types.

[0141] Specific examples of plasticizers include oils, ester-based plasticizers, liquid resins, solid resins (collectively referred to as oils, etc.), etc. These may be used alone or in combination of two or more.

[0142] The content of the plasticizer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 40 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0143] The oil is not particularly limited, and conventionally known oils can be used, such as process oils such as paraffin-based process oils, aromatic process oils, naphthenic process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils, and mixtures thereof. These may be used alone or in combination of two or more. Among these, aromatic process oils are preferred. Specific examples of the aromatic process oils include the Diana Process Oil AH series manufactured by Idemitsu Kosan Co., Ltd.

[0144] 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.

[0145] Examples of ester-based plasticizers include the above-mentioned vegetable oils, synthetic products such as glycerin fatty acid monoesters, glycerin fatty acid diesters, and glycerin fatty acid triesters, and processed vegetable oil products, and phosphoric acid esters (phosphate-based esters, mixtures thereof, etc.). These may be used alone or in combination of two or more.

[0146] As the ester-based plasticizer, for example, a fatty acid ester represented by the following formula can be suitably used. [ka] (In the formula, R 11represents a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkenyl group having 1 to 8 carbon atoms, or a linear or branched alkyl group having 2 to 6 carbon atoms substituted with 1 to 5 hydroxyl groups. 12 represents an alkyl group or alkenyl group having 11 to 21 carbon atoms.

[0147] R 11 Examples of R include a methyl group, an ethyl group, a 2-ethylhexyl group, an isopropyl group, an octyl group, and groups in which these groups are substituted with 1 to 5 hydroxyl groups. 12 Examples of the alkyl group include a straight-chain or branched alkyl group and an alkenyl group such as a lauryl group, a myristyl group, a palmityl group, a stearyl group, and an oleyl group.

[0148] Examples of fatty acid esters include alkyl oleate, alkyl stearate, alkyl linoleate, and alkyl palmitate. Among these, alkyl oleate (methyl oleate, ethyl oleate, 2-ethylhexyl oleate, isopropyl oleate, octyl oleate, etc.) is preferred. In this case, the content of alkyl oleate in 100% by mass of fatty acid ester is preferably 80% by mass or more.

[0149] Examples of fatty acid esters include fatty acid monoesters and fatty acid diesters of fatty acids (oleic acid, stearic acid, linoleic acid, palmitic acid, etc.) and alcohols (ethylene glycol, glycerol, trimethylolpropane, pentaerythritol, erythritol, xylitol, sorbitol, dulcitol, mannitol, inositol, etc.). Of these, oleic acid monoesters are preferred. In this case, the content of oleic acid monoesters in the total amount of fatty acid monoesters and fatty acid diesters (100% by mass) is preferably 80% by mass or more.

[0150] As the ester-based plasticizer, a phosphate ester can also be suitably used. The phosphate ester is preferably a compound having 12 to 30 carbon atoms, and particularly, a trialkyl phosphate having 12 to 30 carbon atoms is preferred. The number of carbon atoms in the trialkyl phosphate refers to the total number of carbon atoms in the three alkyl groups, and the three alkyl groups may be the same or different. Examples of the alkyl group include linear or branched alkyl groups, and may contain heteroatoms such as oxygen atoms or be substituted with halogen atoms such as fluorine, chlorine, bromine, or iodine atoms.

[0151] Examples of phosphate esters include known phosphate ester-based plasticizers such as mono-, di-, or triesters of phosphoric acid with a monoalcohol having 1 to 12 carbon atoms or its (poly)oxyalkylene adduct, and compounds in which one or two of the alkyl groups in the trialkyl phosphate are substituted with phenyl groups. Specific examples include tris(2-ethylhexyl) phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and tris(2-butoxyethyl) phosphate.

[0152] Examples of solid resins include terpene resins (including rosin resins), styrene resins, C5 resins, C9 resins, C5 / C9 resins, coumarone-indene resins (including coumarone and indene simple resins), olefin resins, urethane resins, acrylic resins, pt-butylphenol acetylene resins, and dicyclopentadiene resins (DCPD resins), which are solid at 25°C. The above resins may be hydrogenated. These may be a mixture of one type or two or more types, or the resin itself may be a copolymer of monomer components derived from multiple sources.

[0153] Examples of solid 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, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0154] The softening point of the solid resin is preferably 30° C. or higher, more preferably 60° 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 effect tends to be more suitably obtained. In this specification, the softening point of a 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.

[0155] The terpene resin is not particularly limited as long as it has units derived from a terpene compound, and examples thereof include polyterpenes (resins obtained by polymerizing terpene compounds), terpene aromatic resins (resins obtained by copolymerizing terpene compounds with aromatic compounds), and aromatic-modified terpene resins (resins obtained by modifying terpene resins with aromatic compounds).

[0156] The above terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32), and examples thereof include 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, and γ-terpineol. The terpene compounds also include resin acids (rosin acids) such as abietic acid, neoabietic acid, palustric acid, levopimaric acid, pimaric acid, and isopimaric acid. In other words, the terpene resins also include rosin resins whose main component is rosin acid obtained by processing pine resin. Examples of rosin resins include naturally occurring rosin resins (polymerized rosins) such as gum rosin, wood rosin, and tall oil rosin, as well as modified rosin resins such as maleic acid-modified rosin resin and rosin-modified phenolic resin, rosin esters such as rosin glycerin ester, and disproportionated rosin resin obtained by disproportionating rosin resin.

[0157] The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; and styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene. Of these, styrene is preferred.

[0158] The styrene-based resin is a polymer using a styrene-based monomer as a constituent monomer, and examples thereof include polymers obtained by polymerizing a styrene-based monomer as a main component (50% by mass or more, preferably 80% by mass or more). Specific examples include homopolymers obtained by polymerizing each of styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) alone, copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers of a styrene-based monomer and another monomer copolymerizable therewith.

[0159] Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0160] Of these, α-methylstyrene-based resins (α-methylstyrene homopolymers, copolymers of α-methylstyrene and styrene, etc.) are preferred, and copolymers of α-methylstyrene and styrene are more preferred.

[0161] Liquid resins that have a similar structure to the solid resins but a low softening point can be used. Examples include terpene resins (including rosin resins), styrene resins, C5 resins, C9 resins, C5 / C9 resins, coumarone-indene resins (including coumarone and indene simple resins), olefin resins, urethane resins, acrylic resins, pt-butylphenol acetylene resins, and dicyclopentadiene resins (DCPD resins), which are liquid at 25°C. The above resins may be hydrogenated. These may be a mixture of one type or two or more types, or the resin itself may be a copolymer of monomer components derived from multiple sources.

[0162] Further examples of the liquid resin include liquid farnesene-based polymers such as liquid (meaning liquid at 25°C, the same applies hereinafter) farnesene homopolymer, liquid farnesene-styrene copolymer, liquid farnesene-butadiene copolymer, liquid farnesene-styrene-butadiene copolymer, liquid farnesene-isoprene copolymer, and liquid farnesene-styrene-isoprene copolymer; liquid myrcene-based polymers such as liquid myrcene homopolymer, liquid myrcene-styrene copolymer, liquid myrcene-butadiene copolymer, liquid myrcene-styrene-butadiene copolymer, liquid myrcene-isoprene copolymer, and liquid myrcene-styrene-isoprene copolymer; and liquid styrene-butadiene copolymer. Examples of suitable polymers include liquid diene polymers such as liquid SBR, liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), and liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer); liquid olefin polymers with olefin resins such as polyethylene and polypropylene as hard segments (hard phase) and rubber components as soft segments (soft phase); and liquid ester polymers containing polyester as hard segments and polyether or polyester as soft segments. These polymers may have their ends or main chains modified with polar groups. These may be used alone or in combination of two or more.

[0163] 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., Taoka Chemical Co., Ltd., Sartomer, and Kuraray Co., Ltd.

[0164] 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), calcium carbonate, mica such as sericite, aluminum hydroxide, magnesium oxide, clay, talc, alumina, titanium oxide, 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 polymer component (preferably the rubber component).

[0165] Examples of organic peroxides that can be used include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and 1,3-bis(t-butylperoxypropyl)benzene. These may be used alone or in combination of two or more.

[0166] 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.

[0167] 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 rubber 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.

[0168] The rubber composition can be used (as a rubber composition for tires) in tire components such as treads (cap treads), sidewalls, base treads, undertreads, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulation, chafers, inner liners, and side reinforcing layers of run-flat tires. It is particularly suitable for use in treads. When used in treads, it may be used in either the cap or the base alone, but it is preferred to use it in both.

[0169] (Rubber composition 2) Up to now, rubber composition 1 has been described, and below rubber composition 2 will be described. Rubber composition 2 of the present invention has a temperature dependency of water contact angle that reversibly satisfies the following formula (I) at two temperatures that are 10°C or more apart. This allows tire performance to be reversibly changed in response to temperature changes. Since rubber composition 1 contains the above-mentioned polymer composite, rubber composition 1 inevitably has a temperature dependency of water contact angle that reversibly satisfies the following formula (I) at two temperatures that are 10°C or more apart. Rubber composition 2 will be described below, but the points not described are all the same as rubber composition 1, and the preferred embodiments are also the same. Formula (I) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90

[0170] The reason why such an effect is obtained is not entirely clear, but is presumed to be as follows. Reversibly satisfying the above formula (I) means that the hydrophilicity of the rubber composition reversibly changes with a temperature change, and since the hydrophilicity of the rubber composition reversibly changes with a temperature change, tire performance can be reversibly changed in response to a temperature change. As described above, the present invention solves the problem (objective) of reversibly changing tire performance in response to temperature changes by configuring a rubber composition that satisfies the parameters of the above formula (I). In other words, the parameters do not define the problem (objective). The object of the present application is to reversibly change tire performance in response to temperature changes, and as a means of solving this problem, the rubber composition is configured to satisfy the parameters of the above formula (I). In other words, satisfying the parameters of the above formula (I) is an essential constituent requirement.

[0171] The rubber composition has a temperature dependency of the water contact angle that reversibly satisfies the following formula (I) at two temperatures that are 10° C. or more apart. Formula (I) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90 In this specification, the water contact angle of the rubber composition is measured by the method described in the Examples. Note that in this specification, the water contact angle of the rubber composition means the water contact angle of the rubber composition after vulcanization.

[0172] The two temperatures that are 10°C or more apart are not particularly limited as long as they fall within the range of tire operating temperatures, preferably within the range of -80°C to 80°C, with the lower limit of the temperature range more preferably being -50°C or higher, and even more preferably being -20°C or higher, and the upper limit of the temperature range more preferably being 80°C or lower, and even more preferably being 50°C or lower. The two temperatures are determined by the chemical structure of the temperature-responsive polymer. This is because the critical solution temperature of a temperature-responsive polymer is determined by the chemical structure of the temperature-responsive polymer. For example, the two temperatures with a difference of 10°C or more may be 25°C and 40°C.

[0173] The left side of formula (I) is 90 or less. Normally, the contact angle of water of a rubber composition remains constant regardless of temperature. On the other hand, the contact angle of the above rubber composition decreases by 90% or more at a temperature 10°C or more lower than a certain temperature at which the rubber composition exhibits hydrophobicity, and the rubber composition exhibits greater hydrophilicity. The left side of formula (I) is preferably 87 or less, more preferably 85 or less, even more preferably 84 or less, particularly preferably 83 or less, most preferably 82 or less, more preferably 81 or less, more preferably 80 or less, more preferably 78 or less, more preferably 76 or less, more preferably 74 or less, more preferably 73 or less, and although there is no particular lower limit, it is preferably 5 or more, more preferably 10 or more, even more preferably 30 or more, particularly preferably 50 or more, and most preferably 70 or more. Within the above range, better effects tend to be obtained.

[0174] The contact angle (°) of water at 25°C of the above rubber composition (after vulcanization) is preferably 84 or less, more preferably 83 or less, even more preferably 82 or less, particularly preferably 81 or less, most preferably 78 or less, more preferably 77 or less, more preferably 76 or less, more preferably 75 or less, more preferably 74 or less, more preferably 73 or less, more preferably 72 or less, and although there is no particular lower limit, it is preferably 5 or more, more preferably 10 or more, even more preferably 30 or more, particularly preferably 50 or more, and most preferably 70 or more. When it is within the above range, better effects tend to be obtained.

[0175] As is clear from the above explanation, by blending the above polymer composite into a rubber composition, it is possible to make the left side of formula (I), the water contact angle of the above rubber composition (after vulcanization) at 25°C, fall within the above preferred numerical range. Furthermore, as is clear from the above explanation, the left side of formula (I), the water contact angle of the rubber composition (after vulcanization) at 25°C, can be appropriately adjusted by the type of group (temperature-responsive polymer) whose hydrophilicity changes with temperature possessed by the polymer composite blended into the rubber composition and the content of the polymer composite blended into the rubber composition (the content of the group (temperature-responsive polymer) whose hydrophilicity changes with temperature). For example, by increasing the content of the polymer composite blended into the rubber composition (the content of the group (temperature-responsive polymer) whose hydrophilicity changes with temperature), the left side of formula (I), the water contact angle of the rubber composition (after vulcanization) at 25°C tends to decrease. However, simply compounding a temperature-responsive polymer into a rubber composition will not reversibly satisfy the above formula (I) because the temperature-responsive polymer will flow out of the rubber composition by dissolving in water, for example.

[0176] (tire) The tire of the present invention is manufactured by a conventional method using the above rubber composition (rubber composition 1 or rubber composition 2). That is, the rubber composition, to which various additives are optionally blended, is extruded in an unvulcanized state to match the shapes of the tire components (particularly the tread (cap tread)), molded in a tire building machine by a conventional method, and laminated together with other tire components to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to manufacture the tire.

[0177] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0178] The above-mentioned tires are suitable for use as passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc. [Example]

[0179] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0180] The various chemicals used during synthesis and polymerization were purified according to standard methods as necessary.

[0181] The methods for evaluating the obtained polymers will be summarized below.

[0182] (Measurement of weight average molecular weight (Mw)) The weight average molecular weight (Mw) of the polymer was 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).

[0183] (Polymer structure identification) The polymer structure was identified using a JNM-ECA series NMR device manufactured by JEOL Ltd. The cis content was measured by infrared absorption spectroscopy.

[0184] (Measurement of the left side of formula (III) (remaining rate of reactant)) In measuring the left side of formula (III), the reaction rate of the reactants can be easily measured by a person skilled in the art and calculated using common instrumental analysis. 1 Using instrumental analysis such as H-NMR, the reaction rate of the reactants can be calculated using the peak intensities of the monomer and polymer of the reactants. For example, when the reactant is NIPAM, the hydrogen atom bonded to the carbon adjacent to the nitrogen atom of the monomer appears at 4.18 ppm, but as the reaction progresses, the hydrogen atom bonded to the carbon adjacent to the nitrogen atom of the polymer appears at 4.00 ppm. The remaining rate of the reactants can be calculated by calculating these peak intensities as follows: Formula (III) Remaining monomer rate of reactant: Peak intensity of reactant before stirring / (Peak intensity of reactant before stirring+Peak intensity of reactant after stirring)×100≦50 Each peak intensity is a ratio to an internal standard of a fixed concentration, in which TMS (tetramethylsilane) was used as the internal standard.

[0185] (Measurement of the left side of formula (IV) (residual ratio of conjugated diene compound)) In measuring the left side of formula (IV), the reaction rate of the conjugated diene can be easily measured by a person skilled in the art and calculated using a general instrumental analysis. 1Using instrumental analysis such as H-NMR, the reaction rate of the reactant can be calculated using the peak intensities derived from the polymer before the reaction and the peak intensities derived from the polymer after the reaction. For example, when the reactant is BR, hydrogen atoms bonded to unreacted carbon-carbon double bonds appear at 5.38 ppm, but as the reaction progresses, the intensity of this peak approaches 0. The residual rate of conjugated dienes can be calculated by calculating these peak intensities as follows: Formula (IV) Residual rate of conjugated diene: double bond peak intensity derived from conjugated diene before stirring / (double bond peak intensity derived from conjugated diene before stirring+double bond peak intensity derived from conjugated diene after stirring)×100≦99 Each peak intensity is a ratio to an internal standard of a fixed concentration, in which TMS (tetramethylsilane) was used as the internal standard.

[0186] <Polymer production example> (Polymerization of Polymer A) A heat-resistant vessel thoroughly purged with nitrogen was charged with 1500 ml of n-hexane, 25 g of styrene, 75 g of 1,3-butadiene, 0.2 mmol of tetramethylethylenediamine, and 0.24 mmol of n-butyllithium, and the mixture was stirred at 0°C for 48 hours. The reaction was then stopped by adding alcohol, and 24 mL of a 1 mmol / L BHT ethanol solution was added to the reaction solution. 10 mL of the polymerization solution was sampled, precipitated with 40 mL of ethanol, and dried to obtain Polymer A. The resulting polymer (SBR) had a weight-average molecular weight of 460,000, a styrene content of 25% by mass, and a yield of 99%.

[0187] (Polymerization of Polymer B) Preparation of catalyst solution B 350 mL of cyclohexane, 35 g of butadiene monomer, 54 mL of a 20% by volume neodymium versatate / cyclohexane solution, and 130 mL of a PMAO / toluene solution were added to a dried, nitrogen-purged 1 L pressure-resistant stainless steel vessel and stirred for 30 minutes. Then, 30 mL of a 1 M DAIBAH / hexane solution was added and stirred for 30 minutes. Then, 15 mL of a 1 M 2-chloro-2-methylpropane / cyclohexane solution was added and stirred for 30 minutes to prepare catalyst solution A. Polymerization of polymer B A dried, nitrogen-purged 3 L pressure-resistant stainless steel vessel was charged with 2000 mL of cyclohexane and 100 g of butadiene. 10 mL of a 1 mol / L TIBA / normal hexane solution was added and stirred for 5 minutes. After confirming that the solution was clear, 30 mL of catalyst solution A was added and the polymerization reaction was carried out at 80 °C for 3 hours. After 3 hours, 50 mL of a 1 M isopropanol / THF solution was added dropwise as a reaction terminator to terminate the reaction. A 10 mL aliquot of the polymerization solution was collected, precipitated with 40 mL of ethanol, and dried to obtain polymer B. The resulting polymer (BR) had a weight-average molecular weight of 800,000, a cis content of 98% by mass, and a yield of 99%.

[0188] (Polymerization of Polymer C) A 3L glass vessel was dried and purged with nitrogen. 1800 mL of toluene and 100 g (880 mmol) of NIPAM (isopropylacrylamide) monomer were added and stirred at room temperature until a homogeneous solution was obtained. Then, 16.7 mmol (2 mol% of the NIPAM unit) of AIBN (azobisisobutyronitrile) was added and stirred at 70-110°C for 5 hours, confirming the precipitation of the polymer. After cooling to room temperature, 200 mL of THF was added to obtain a homogeneous solution. The solvent was then distilled off and the mixture was dried under reduced pressure at 80°C / 1 mmHg until the loss on drying was 0.5% or less, producing poly(N-isopropylacrylamide) (PNIPAM). 1 The reaction rate calculated from the protons of NIPAM before and after the reaction (PNIPAM) using H-NMR was 98%.

[0189] (Comparative Example 1) Preparation of Polymer Composite 1 The polymer B was pressed into a sheet having a thickness of 2 mm.

[0190] (Comparative Example 2) Preparation of Polymer Composite 2 The polymerization solution of polymer B and polymer C were mixed to a solid content ratio of 100 / 10, and then 200 mL of THF was added to obtain a homogeneous solution. The solvent was then distilled off, and the mixture was dried under reduced pressure at 80°C / 1 mmHg until the loss on drying was 0.5% or less, and then pressed into a sheet having a thickness of 2 mm.

[0191] (Comparative Example 3) Preparation of Polymer Composite 3 The same treatment as in Comparative Example 2 was carried out except that the solid content ratio was adjusted to 100 / 100.

[0192] (Comparative Example 4) Preparation of Polymer Composite 4 The same treatment as in Comparative Example 1 was carried out except that the polymer was changed to the above polymer A.

[0193] (Comparative Example 5) Preparation of Polymer Composite 5 The same treatment as in Comparative Example 2 was carried out except that the polymer was changed to the above polymer A and the solid content ratio was adjusted to 100 / 10.

[0194] (Comparative Example 6) Preparation of Polymer Composite 6 The same treatment as in Comparative Example 2 was carried out except that the polymer was changed to the above polymer A and the solid content ratio was adjusted to 100 / 100.

[0195] (Comparative Example 7) Preparation of Polymer Composite 7 The polymerization solution of polymer B (corresponding to 100 g of solid content) and 33 mmol of AIBN were added, and then 200 mL of THF was added, followed by stirring for 5 hours at 70 to 110° C. The solvent was distilled off, and the mixture was dried under reduced pressure at 80° C. / 1 mmHg until the loss on drying was 0.5% or less, and then pressed into a sheet with a thickness of 2 mm.

[0196] (Comparative Example 8) Preparation of Polymer Composite 8 The same treatment as in Comparative Example 7 was carried out except that the polymer was changed to the above polymer A.

[0197] (Comparative Example 9) Preparation of Polymer Composite 9 The polymerization solution of polymer B and NIPAM (isopropylacrylamide) were mixed at a solid content ratio of 100 / 100, and then 200 mL of THF was added to form a homogeneous solution, which was then stirred for 5 hours at 70° C. to 110° C. The solvent was distilled off, and the mixture was dried under reduced pressure at 80° C. / 1 mmHg until the loss on drying was 0.5% or less, and then pressed into a sheet with a thickness of 2 mm.

[0198] (Comparative Example 10) Production of Polymer Composite 10 The same treatment as in Comparative Example 9 was carried out except that the polymer was changed to the above polymer A.

[0199] Example 1: Production of polymer composite 11 To the polymerization solution of polymer B (corresponding to 100 g of solid content, solvent: cyclohexane), 10 g of NIPAM (isopropylacrylamide) and 1.7 mmol of AIBN (azobisisobutyronitrile) were added, and the mixture was stirred for 5 hours at 70 to 110° C. The solvent was distilled off, and the mixture was dried under reduced pressure at 80° C. / 1 mmHg until the loss on drying was 0.5% or less, and then pressed into a sheet with a thickness of 2 mm. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 1, and the value of the left side of formula (IV) was 97.

[0200] Example 2: Production of polymer composite 12 The same treatment as in Example 1 was carried out except that the amount of NIPAM charged was changed to 100 g and the amount of AIBN charged was changed to 16.7 mmol. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 2, and the value of the left side of formula (IV) was 96.

[0201] Example 3: Preparation of polymer composite 13 The same treatment as in Example 1 was carried out except that the polymer was changed to the above polymer A and the solvent was changed to n-hexane. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 24, and the value of the left side of formula (IV) was 96.

[0202] Example 4: Preparation of polymer composite 14 The same treatment as in Example 1 was carried out except that the polymer was changed to the above polymer A, the amount of NIPAM charged was changed to 100 g, the amount of AIBN charged was changed to 16.7 mmol, and the solvent was changed to n-hexane. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 25, and the value of the left side of formula (IV) was 95.

[0203] Example 5: Preparation of Polymer Composite 15 The same treatment as in Example 1 was carried out except that the amount of NIPAM charged was changed to 50 g and the amount of AIBN charged was changed to 8.35 mmol. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 1, and the value of the left side of formula (IV) was 97.

[0204] (Example 6) Preparation of polymer composite 16 The same treatment as in Example 1 was carried out except that the polymer was changed to the above polymer A, the amount of NIPAM charged was changed to 50 g, the amount of AIBN charged was changed to 8.35 mmol, and the solvent was changed to n-hexane. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 24, and the value of the left side of formula (IV) was 96.

[0205] (Example 7) Preparation of Polymer Composite 17 The same treatment as in Example 1 was carried out except that NIPAM was replaced with NNPAM (Nn-propylacrylamide). 1The reaction rate calculated from the protons before (NNPAM) and after (PNNPAM) reaction by H-NMR was 99%. The value of the left side of formula (III) was 1, and the value of the left side of formula (IV) was 97.

[0206] (Example 8) Preparation of polymer composite 18 The same treatment as in Example 1 was carried out except that NIPAM was replaced with NDEAM (N,N-diethylacrylamide). 1 The reaction rate calculated from the protons before (NDEPAM) and after (PNDEPAM) reaction by H-NMR was 99%. The value of the left side of formula (III) was 1, and the value of the left side of formula (IV) was 97.

[0207] (Example 9) Preparation of Polymer Composite 19 The same treatment as in Example 1 was carried out except that NIPAM was replaced with NMNIPAM (N-isopropyl, N-methylacrylamide). 1 The reaction rate calculated from the protons of NMNIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 1, and the value of the left side of formula (IV) was 97.

[0208] (Example 10) Production of polymer composite 20 The same treatment as in Example 1 was carried out except that the polymer was changed to natural rubber (weight average molecular weight: 600,000) and the solvent was changed to n-hexane. 1 The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 24, and the value of the left side of formula (IV) was 95.

[0209] (Example 11) Preparation of polymer composite 21 The same treatment as in Example 1 was carried out except that the polymer was changed to natural rubber (weight average molecular weight: 600,000), the amount of NIPAM charged was changed to 100 g, the amount of AIBN charged was changed to 16.7 mmol, and the solvent was changed to n-hexane. 1The reaction rate calculated from the protons of NIPAM before and after the reaction using H-NMR was 99%. The value of the left side of formula (III) was 24, and the value of the left side of formula (IV) was 95.

[0210] The obtained polymer composite was evaluated as follows, and the results are shown in Tables 2 and 3.

[0211] (Measurement of water contact angle of polymer composite) The contact angle (°) of water was measured using a polymer composite sheet with a thickness of 2 mm. Specifically, a 2 mm thick polymer composite sheet was kept at the measurement temperature for 10 minutes, and then a 20 μL water droplet was dropped onto the sheet surface. After 20 seconds, the contact angle of the droplet was measured using a contact angle measuring device. The measurements in Table 2 were first carried out at a measurement temperature of 25°C, and then at a measurement temperature of 40°C. This result was taken as the first measurement result. After the first measurement, the surface of the polymer composite sheet after measurement (measurement surface) was wiped with water-soaked paper and then wiped with dry paper. The dry-wiped polymer composite sheet was then cooled to room temperature, and a second measurement was carried out at a measurement temperature of 25°C, and then at a measurement temperature of 40°C. This result was taken as the second measurement result. Furthermore, the measurements in Table 3 were first carried out at a measurement temperature of 20°C, then at a measurement temperature of 30°C, and then at a measurement temperature of 40°C. This result was taken as the first measurement result. After the first measurement, the surface of the polymer composite sheet after measurement (measurement surface) was wiped with water-soaked paper and then wiped with dry paper. The dry-wiped polymer composite sheet was then cooled to room temperature, and a second measurement was carried out at a measurement temperature of 20°C, then at a measurement temperature of 30°C, and then at a measurement temperature of 40°C. This result was taken as the second measurement result. The results are shown in Tables 2 and 3.

[0212] [Table 2]

[0213] [Table 3]

[0214] The results in Tables 2 and 3 show that the polymer composite of the example formed by stirring a conjugated diene polymer having a weight-average molecular weight of 100,000 or more as measured by gel permeation chromatography, a radical generator, and a reactant having one or more heteroatoms and one or more carbon-carbon double bonds in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents at a temperature of 40°C to 200°C reversibly satisfies the temperature dependence of the water contact angle as defined by formula (II) above at two temperatures that are 10°C or more apart. The polymer composite of the example is a polymer composite in which the temperature dependence of the water contact angle reversibly satisfies the above formula (II) at two temperatures that are 10°C or more apart, and it was therefore found that tire performance can be reversibly changed in response to temperature changes.

[0215] FIG. 1 shows the results of measuring the contact angle of water with respect to the polymer composites of Example 2 and Comparative Example 4 at different temperatures. From Figure 1, it can be seen that for polymer A (SBR), the water contact angle remains constant even when the temperature changes. On the other hand, for the polymer composite of the present invention, the water contact angle remains constant at temperatures above 40°C, whereas the contact angle decreases below 40°C. Furthermore, even when the same sample was measured multiple times while changing the temperature, it was confirmed that the water contact angle remains constant at temperatures above 40°C, whereas the contact angle decreases below 40°C. These results demonstrate that the polymer composite is bonded with a group (temperature-responsive polymer) whose hydrophilicity changes with temperature, and that the temperature dependence of the water contact angle remains the same even when the temperature is repeatedly changed. Therefore, it was found that the temperature dependence of the water contact angle of the polymer composite of the present invention reversibly satisfies the above formula (II) at two temperatures that are 10°C or more apart.

[0216] The various chemicals used in the following Examples and Comparative Examples will be collectively described below. Polymer A: the above polymer A Polymer B: the above polymer B Polymer complex 3: the above polymer complex 3 Polymer Complex 6: The above-mentioned polymer complex 6 Polymer complex 12: the above polymer complex 12 Polymer complex 14: The above polymer complex 14 NR: Natural rubber as above Polymer complex 21: the above polymer complex 21 Carbon black: N134 (N2SA:148m) manufactured by Cabot Japan Co., Ltd. 2 / g, DBP: 123ml / 100g) Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Tegussa 2 / g) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Tegussa Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: NOF Corporation stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator (1): Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator (2): Noccelaer D (1,3-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0217] Examples and Comparative Examples According to the formulation shown in Table 4, chemicals 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 resulting unvulcanized rubber composition was press-vulcanized at 170° C. for 15 minutes to obtain a vulcanized rubber composition sheet having a thickness of 2 mm. In Table 4, the amount of the rubber component is adjusted to 100 parts by mass, taking into consideration the conjugated diene polymer (rubber component) contained in the polymer composite.

[0218] The resulting vulcanized rubber composition sheet having a thickness of 2 mm was used to measure the contact angle of the rubber composition with water. Specifically, instead of the 2 mm thick polymer composite sheet used in the above (measurement of the contact angle of the polymer composite with water), a 2 mm thick vulcanized rubber composition sheet was used to measure the contact angle of the rubber composition with water. The results are shown in Table 4.

[0219] [Table 4]

[0220] From Table 4, it was found that the rubber compositions of the examples containing the polymer composite of the present invention had temperature dependence of the water contact angle that reversibly satisfied the following formula (I) at two temperatures that were 10°C or more apart. It was found that the rubber compositions of the examples, in which the temperature dependence of the water contact angle that reversibly satisfied the following formula (I) at two temperatures that were 10°C or more apart, were able to reversibly change tire performance in response to temperature changes.

Claims

1. It is formed from a conjugated diene polymer having a weight average molecular weight of 100,000 or more as measured by gel permeation chromatography, At two temperatures that are 10°C or more apart, A rubber composition comprising a polymer composite in which the temperature dependence of a water contact angle reversibly satisfies the following formula (II): Equation (II) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 85 the polymer composite is a conjugated diene polymer to which a group formed by a reactant having one or more heteroatoms and one or more carbon-carbon double bonds is bonded, the conjugated diene polymer is styrene butadiene rubber, the polymer composite is a polymer that exhibits a lower critical solution temperature in water, The rubber composition has a silica content of 10 parts by mass or more and 150 parts by mass or less and a carbon black content of 0.1 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the rubber component, The rubber composition has a butadiene rubber content of 10% by mass or more and 90% by mass or less relative to 100% by mass of the rubber component.

2. The rubber composition according to claim 1, wherein the polymer composite has a group whose hydrophilicity changes with temperature.

3. 3. The rubber composition according to claim 2, wherein said group is a group that exhibits a lower critical solution temperature in water.

4. 4. The rubber composition according to claim 2, wherein the group is a poly(N-substituted (meth)acrylamide).

5. The rubber composition according to any one of claims 2 to 4, wherein the group is a group represented by the following formula (I): 【Chemical 1】 (wherein n represents an integer of 1 to 1000, 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 is not a hydrogen atom, and R １ and R ２ may form a ring structure.)

6. 6. The rubber composition according to claim 2, wherein the group is poly(N-isopropylacrylamide).

7. The polymer composite is a conjugated diene polymer having a weight average molecular weight of 100,000 or more as measured by gel permeation chromatography; A radical generator; a reactant having one or more heteroatoms and one or more carbon-carbon double bonds; in at least one solvent selected from the group consisting of hydrocarbon solvents, aromatic solvents, and aprotic polar solvents, The rubber composition according to any one of claims 1 to 6, which is formed by stirring at a temperature of 40°C or higher and 200°C or lower.

8. 8. The rubber composition according to claim 7, wherein the polymer composite has a residual rate of reactants before and after stirring that satisfies the following formula (III): Formula (III) Remaining rate of reactant: peak intensity of reactant before stirring / (peak intensity of reactant before stirring+peak intensity of reactant after stirring)×100≦50

9. 9. The rubber composition according to claim 7, wherein the polymer composite has a residual rate of a conjugated diene unit in the conjugated diene polymer before and after stirring that satisfies the following formula (IV): Formula (IV) Residual rate of conjugated diene: double bond peak intensity derived from conjugated diene before stirring / (double bond peak intensity derived from conjugated diene before stirring+double bond peak intensity derived from conjugated diene after stirring)×100≦99

10. The rubber composition according to any one of claims 1 to 9, which is for use in a tire tread.

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

12. 12. The tire of claim 11, wherein the tire component is a tread.

13. The rubber composition according to any one of claims 1 to 10, wherein the temperature dependency of the water contact angle reversibly satisfies the following formula (I) at two temperatures that are 10°C or more apart: Formula (I) Temperature dependence of contact angle = Contact angle on low temperature side / Contact angle on high temperature side × 100 ≦ 90

14. Nitrogen adsorption specific surface area is 145m ２ The rubber composition according to any one of claims 1 to 10 and 13, comprising carbon black of at least 1 / g.

15. The rubber composition according to any one of claims 1 to 10, 13 and 14, which is for use in a tire tread.

16. A tire having tire components using the composition according to any one of claims 1 to 10 and 13 to 15.

17. 17. The tire of claim 16, wherein the tire component is a tread.

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