Rubber composition, crosslinked body and tire

Abstract

A rubber composition containing, as (A) polymer, a polymer having a carbon-carbon unsaturated bond, in which the composition ratio (molar ratio) of structural units represented by formula (1), formula (2), formula (3), and formula (4) is respectively set to p, q, r, s, and the value α represented by mathematical formula (i) is 0.70 to 0.99, and containing, as (B) resin, a thermoplastic resin, and containing 60 to 95 mass% of the (A) polymer relative to the total amount of the (A) polymer and the (B) resin. α = (p + (0.5 × r)) / (p + q + (0.5 × r) + s) … (i)

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on Japanese Patent Application No. 2019-14823 filed on January 30, 2019, and the contents thereof are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a rubber composition, a crosslinked product, and a tire, and more particularly, to a rubber composition suitable for use as a tire. Background Art

[0004] Polymers having carbon-carbon unsaturated bonds, represented by conjugated diene polymers, are widely used as rubber materials. Conjugated diene polymers (e.g., styrene-butadiene copolymers) are widely used in various industrial products such as pneumatic tires, anti-vibration rubbers, and hoses due to their excellent properties, including heat resistance, wear resistance, mechanical strength, and moldability. Furthermore, it has been proposed to produce high-strength, low-wear cross-linked rubbers by using hydrogenated conjugated diene polymers, obtained by hydrogenating a portion of the unsaturated bonds in the conjugated diene polymers (e.g., see Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2015 / 064646 Summary of the Invention

[0008] Extending the lifespan and increasing the number of years of use of rubber products contributes to reducing environmental impact. Furthermore, in tire applications, tire degradation also affects the vehicle's high-speed performance and driving stability. Therefore, there is a need for materials that can produce cross-linked rubber with superior fatigue resistance (one representative parameter is crack growth resistance) and wear resistance, as well as higher strength than conventional materials.

[0009] The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a rubber composition capable of obtaining a cross-linked rubber having excellent wear resistance and crack growth resistance and high strength.

[0010] The present inventors have conducted intensive research to solve the aforementioned problems of the prior art and have found that the aforementioned problems can be solved by crosslinking a rubber composition containing a highly saturated diene polymer and a thermoplastic resin. Specifically, the present disclosure provides the following aspects.

[0011] [1] A rubber composition containing (A) a polymer having a carbon-carbon unsaturated bond, having a value α represented by the following mathematical expression (i) of 0.70 to 0.99 when the composition ratios (molar ratios) of a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3), and a structural unit represented by the following formula (4) in the polymer are respectively set to p, q, r, s, and (B) a thermoplastic resin, containing 60 to 95 mass% of the (A) polymer with respect to the total amount of the (A) polymer and the (B) resin.

[0012] α = (p + (0.5 x r)) / (p + q + (0.5 x r) + s)... (i)

[0013]

[0014] [2] A crosslinked body obtained using a rubber composition containing the (A) polymer and the (B) resin.

[0015] [3] A tire formed of one or both of a tread and a sidewall using the crosslinked body of the above [2].

[0016] According to the present disclosure, by producing a rubber composition in which a highly saturated diene-based polymer and a thermoplastic resin are mixed at a prescribed ratio, a crosslinked rubber in which wear resistance, crack growth resistance, and strength are balanced and improved can be obtained. DETAILED DESCRIPTION

[0017] Hereinafter, matters related to the implementation of the present disclosure are described in detail.

[0018] Rubber composition

[0019] The rubber composition of the present disclosure contains a highly saturated diene-based polymer and a thermoplastic resin.

[0020] Highly saturated diene-based polymer

[0021] The highly saturated diene-based polymer of the present disclosure (hereinafter, also referred to as (A) polymer) is a polymer having a carbon-carbon unsaturated bond. For the (A) polymer, when the composition ratios (molar ratios) of a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), a structural unit represented by the following formula (3), and a structural unit represented by the following formula (4) in the polymer are respectively set to p, q, r, s, the value α represented by the following mathematical expression (i) is 0.70 to 0.99.

[0022] α = (p + (0.5 x r)) / (p + q + (0.5 x r) + s)... (i)

[0023] (A) Polymer can be produced by, for example, a method including a step of polymerizing a monomer containing butadiene to obtain a conjugated diene-based polymer having a living terminal (polymerization step), and a step of hydrogenating the conjugated diene-based polymer (hydrogenation step). In addition, the method can arbitrarily include a step of modifying the terminal of the conjugated diene-based polymer obtained by the polymerization step (modification step). Specifically, it can be produced in a manner adapted to the purpose of use by appropriately changing the molecular weight, the amount of aromatic vinyl compound, the content of vinyl bond, the hydrogenation rate, the kind of modifier, and the like in accordance with the method described in International Publication No. 2014 / 133097. In addition, it can be produced by copolymerizing a diene monomer such as 1,3-butadiene with a non-conjugated olefin in accordance with the method described in International Publication No. 2015 / 190073. Hereinafter, the hydrogenated conjugated diene-based polymer is exemplified to describe the (A) Polymer and the method for producing the same in detail.

[0024] (Polymerization Step)

[0025] When the (A) Polymer is a hydrogenated conjugated diene-based polymer, the conjugated diene-based polymer before hydrogenation is a polymer having a structural unit derived from a conjugated diene compound. The conjugated diene-based polymer before hydrogenation is preferably a copolymer having a structural unit derived from a conjugated diene compound and a structural unit derived from an aromatic vinyl compound. The present polymerization step is a step of polymerizing a monomer containing a conjugated diene compound, preferably containing a conjugated diene compound and an aromatic vinyl compound, to obtain a conjugated diene-based polymer having a living terminal.

[0026] In the above polymerization, as the conjugated diene compound, 1,3-butadiene can be preferably used. In addition, in the above polymerization, a conjugated diene compound other than 1,3-butadiene can be used in addition to 1,3-butadiene. Such a conjugated diene compound is preferably capable of copolymerizing with 1,3-butadiene and an aromatic vinyl compound. As specific examples of the conjugated diene compound other than 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and the like can be given, among which isoprene is preferred. Note that the conjugated diene compound can be used alone as one compound or in combination as two or more compounds.

[0027] As the aromatic vinyl compound, for example, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, a-methylstyrene, N,N-dimethylaminoethylstyrene, diphenylethylene, and the like can be given. Among these, the aromatic vinyl compound is particularly preferably one or more compounds selected from the group consisting of styrene and a-methylstyrene. Note that the aromatic vinyl compound can be used alone as one compound or in combination as two or more compounds.

[0028] The conjugated diene-based polymer obtained by the present polymerization procedure can be a homopolymer of the conjugated diene compound, or a copolymer of the conjugated diene compound and an aromatic vinyl compound. The copolymer of the conjugated diene compound and the aromatic vinyl compound is preferred. In addition, as the conjugated diene compound, a copolymer using 1,3-butadiene and a conjugated diene compound other than 1,3-butadiene can be used. From the viewpoint of high activity in anionic polymerization, the conjugated diene-based polymer is preferably a copolymer of 1,3-butadiene and styrene.

[0029] In the copolymer of the conjugated diene compound and the aromatic vinyl compound, from the viewpoint of good low hysteresis loss properties of the crosslinked rubber, the use amount of the aromatic vinyl compound with respect to the total amount of the monomers used in the polymerization is preferably 10 to 50% by mass, and more preferably 15 to 40% by mass. In addition, by making the content of the aromatic vinyl compound within the above range, productivity and strength can be both achieved. The monomers used in the production of the conjugated diene-based polymer before hydrogenation preferably contain, with respect to 100 parts by mass of the monomers, 50 to 90 parts by mass of butadiene, 10 to 50 parts by mass of the aromatic vinyl compound, and 0 to 40 parts by mass of a conjugated diene compound other than butadiene. By being such a blending amount, it is preferable in terms of achieving both productivity and strength of the crosslinked rubber.

[0030] Note that the above exemplified conjugated diene compound and aromatic vinyl compound each have the same effect in that a conjugated diene-based polymer having a living terminal can be obtained. Therefore, even a compound not described in the examples described later can be used in the present disclosure.

[0031] At the time of polymerization, other monomers than the conjugated diene compound and the aromatic vinyl compound can be used. As the other monomers, for example, acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, and the like can be given. The use amount of the other monomers with respect to the total amount of the monomers used in the polymerization is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less.

[0032] As the polymerization method for obtaining the conjugated diene-based polymer of the present disclosure, any one of a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method can be used, and a solution polymerization method is particularly preferred. In addition, as the polymerization form, any one of a batch type and a continuous type can be used. When a solution polymerization method is used, as one example of a specific polymerization method, a method in which monomers containing a conjugated diene compound are polymerized in the presence of a polymerization initiator and a randomizer used as necessary in an organic solvent can be given.

[0033] As the polymerization initiator, at least one of an alkali metal compound and an alkaline earth metal compound can be used. As the alkali metal compound and the alkaline earth metal compound, substances commonly used as initiators for anionic polymerization can be used, for example, alkyl lithiums such as methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, and tert-butyl lithium, 1,4-dilithium butane, phenyl lithium, distyryl lithium, naphthyl lithium, sodium naphthyl, potassium naphthyl, di-n-butyl magnesium, di-n-hexyl magnesium, potassium ethoxide, calcium stearate, etc. Among these, lithium compounds are preferred.

[0034] In addition, the polymerization reaction can be carried out in the presence of a compound (hereinafter also referred to as compound (R)) obtained by mixing at least any one of the above-mentioned alkali metal compound and alkaline earth metal compound and a compound having a functional group that interacts with silica (hereinafter also referred to as compound (C1)). By carrying out polymerization in the presence of compound (R), a functional group that interacts with silica can be introduced into the polymerization initiation end of the conjugated diene polymer. It should be noted that in this specification, "interaction" refers to the formation of a covalent bond between molecules, or the formation of an intermolecular force weaker than a covalent bond (for example, an electromagnetic force that acts between molecules such as an ion-dipole interaction, a dipole-dipole interaction, a hydrogen bond, a van der Waals force, etc.). In addition, "a functional group that interacts with silica" means a group of atoms that interact with silica, such as at least one nitrogen atom, a sulfur atom, a phosphorus atom, an oxygen atom, etc.

[0035] The compound (R) is preferably a reaction product of a lithium compound such as an alkyllithium and a nitrogen-containing compound such as a secondary amine compound. Specific examples of the nitrogen-containing compound include dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, di(2-ethylhexyl)amine, diallylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine, and 1,3-bis(trimethylsilyl)-1,3,5-triazinane. When the polymerization is carried out in the presence of the compound (R), the compound (R) can be prepared by pre-mixing at least one of an alkali metal compound and an alkaline earth metal compound with the compound (C1), and then adding the prepared compound (R) to the polymerization system for polymerization. Alternatively, at least one of an alkali metal compound and an alkaline earth metal compound and the compound (C1) may be added to the polymerization system, and the two may be mixed in the polymerization system to prepare the compound (R) and perform polymerization.

[0036] A randomizer can be used for the purpose of adjusting the content ratio of vinyl bonds (vinyl content) and the like. As examples of the randomizer, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-bis(tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, tetramethylethylenediamine, and the like can be given. They can be used alone or in combination of two or more.

[0037] As the organic solvent used in the polymerization, any organic solvent which is inactive to the reaction can be used, and for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and the like can be used. Among them, hydrocarbons having 3 to 8 carbon atoms are preferred, and as specific examples thereof, for example, n-pentane, isopentane, n-hexane, cyclohexane, propylene, 1-butene, isobutylene, trans-2-butene, cis-2-butene, 1-pentyn, 2-pentyn, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, cyclohexene, and the like can be given. It should be noted that as the organic solvent, one kind can be used alone or two or more kinds can be used in combination.

[0038] When solution polymerization is used, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of balancing the maintenance of the productivity and the easiness of polymerization control. The temperature of the polymerization reaction is preferably -20 to 150°C, more preferably 0 to 120°C, particularly preferably 20 to 100°C. In addition, the polymerization reaction is preferably performed under a pressure sufficient to maintain the monomer substantially in a liquid phase. Such a pressure can be obtained by pressurizing the inside of the reactor with a gas inactive to the polymerization reaction or the like.

[0039] Thus, a conjugated diene-based polymer having a living terminal can be obtained. The weight average molecular weight (Mw) of the conjugated diene-based polymer is preferably 1.0 x 10 5 to 2.0 x 10 6 If the Mw is less than 1.0 x 10 5 , there is a tendency that the wear resistance and the low fuel consumption performance of the obtained crosslinked rubber easily decrease, and if it is more than 2.0 x 10 6 , there is a tendency that the processability easily decreases. The Mw is more preferably 1.0 x 10 5 , further preferably 1.5 x 10 5 or more. In addition, the Mw is more preferably 1.5 x 10 6 or more, further preferably 1.0 x 10 6 or less.

[0040] The 1,2-vinyl content of the conjugated diene-based polymer obtained by the above polymerization is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. In addition, the 1,2-vinyl content is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less. If the 1,2-vinyl content is less than 5% by mass, there is a tendency for the grip characteristics to become low, and if it exceeds 70% by mass, there is a tendency for the wear resistance to easily become poor. Note that the 1,2-vinyl content is a value determined by1H-NMR measurement. 1 H-NMR measurement.

[0041] The conjugated diene-based polymer before hydrogenation of the present disclosure is preferably a random copolymer of structural units derived from a conjugated diene compound and structural units derived from an aromatic vinyl compound. At this time, it is preferable in terms of being able to make the dispersibility of the filler more favorable. Note that the random copolymer can have a block portion composed of a conjugated diene compound at one or both of the terminals.

[0042] (Modification step)

[0043] The modification step is a step of reacting the active terminal of the conjugated diene-based polymer obtained by the above polymerization step and a compound having a functional group that interacts with silica (hereinafter, also referred to as compound (C2)). By this step, a functional group that interacts with silica can be introduced to the polymerization end terminal of the conjugated diene-based polymer. Note that the active terminal in the present specification refers to a portion other than the structure derived from a monomer having a carbon-carbon double bond (more specifically, a metal terminal) present at one end of the molecular chain.

[0044] The conjugated diene-based polymer used in the modification reaction in this step (hereinafter, also referred to as terminal modification reaction) can be a polymer in which the polymerization initiation terminal has not been modified, or a modified polymer, as long as it has an active terminal. The compound (C2) is not particularly limited as long as it is a compound that can react with the active terminal of the conjugated diene-based polymer. From the viewpoint of being able to make the low fuel consumption performance of the crosslinked body obtained using the rubber composition of the present disclosure good, the compound (C2) is preferably a compound having one or more functional groups selected from the group consisting of an amino group, a group having a carbon-nitrogen double bond, a nitrogen-containing heterocyclic group, a phosphine group, an epoxy group, a thioepoxy group, a protected hydroxyl group, a protected thiol group, and a hydrocarbon oxy silyl group, and capable of reacting with the polymer active terminal. Note that the amino group includes a protected primary amino group, a protected secondary amino group, and a tertiary amino group. Specifically, as the compound (C2), at least one compound selected from the group consisting of a compound represented by the following formula (9), a compound represented by the following formula (10), a compound represented by the following formula (11), and a compound represented by the following formula (12) can be preferably used.

[0045]

[0046] (In formula (9), A 1 is a monovalent functional group having at least one atom selected from nitrogen, phosphorus, oxygen, sulfur, and silicon, and bonded to R 5 with a nitrogen atom, a phosphorus atom, an oxygen atom, a sulfur atom, a silicon atom, or a carbon atom contained in a carbonyl group, or is a (thio)epoxy group. R 3 and R 4 are each independently a hydrocarbon group, R 5 is a hydrocarbylene group, and r is an integer of 0 to 2. When a plurality of R 3 are present, the plurality of R 3 are the same group or different groups. When a plurality of R 4 are present, the plurality of R 4 are the same group or different groups)

[0047]

[0048] (In formula (10), A 2 is a monovalent functional group having at least one atom selected from nitrogen, phosphorus, oxygen, sulfur, and silicon, and not having an active hydrogen, and bonded to R 9 with a nitrogen atom, a phosphorus atom, an oxygen atom, a sulfur atom, or a silicon atom, or is a hydrocarbon group having 1 to 20 carbon atoms. R 6 and R 7 are each independently a hydrocarbon group, R 8 is a hydrocarbylene group, R 9 is a single bond or a hydrocarbylene group, and m is 0 or 1. When a plurality of R 7 are present, the plurality of R 7 are the same group or different groups)

[0049]

[0050] (In formula (11), A 3 is a monovalent group bonded to L 2 with an imino group, an amido group, a (thio)carbonyl group, a (thio)carbonyloxy group, a sulfide group, or a poly-sulfide group, or is a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate group, a metal salt of a (thio)carboxylate group, -COX 1 (X 1 is a halogen atom), an imidazole group, or a group represented by the following formula (11a). L 2 and L 3 are each independently a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, R 9 and R 10 are each independently a hydrocarbon group. k is an integer of 0 to 2, and j is 0 or 1. For R9 10 3 each symbol of R 4 , R 11 , R 12 and L 2 is independently a group common to each other or a different group. Multiple i in the formula is a same number or a different number)

[0051]

[0052] (incidentally, in formula (11a), L 4 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, R 11 and R 12 are each independently a hydrocarbyl group. i is an integer of 0 to 3. "*" indicates a site bonded to L 2 . As for each symbol of R 11 , R 12 and L 4 , the symbol represents a group common to each other or a different group. Multiple i in the formula is a same number or a different number)

[0053]

[0054] (incidentally, in formula (12), A 4 is an imino group, an amido group, a (thio)carbonyl group or a (thio)carboxy group, Z 1 is a t-valent group having 1 to 20 carbon atoms which contains a nitrogen atom or does not contain a nitrogen atom, L 5 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, L 6 is a hydrocarbylene group having 1 to 20 carbon atoms, R 13 and R 14 are each independently a hydrocarbyl group. h is 0 or 1, and t is 2 or 3. As for each symbol of R 14 , L 5 , L 6 and A 4 , the symbol represents a group common to each other or a different group. Multiple h in the formula is a same number or a different number)

[0055] In the above formula (9) and formula (10), the hydrocarbyl group of R 3 , R 4 , R 6 and R 7 is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.

[0056] R 5 and R 9Preferred are linear or branched alkanediyl groups having 1 to 20 carbon atoms, cycloalkylene groups having 3 to 20 carbon atoms, or arylene groups having 6 to 20 carbon atoms.

[0057] From the viewpoint of improving the reactivity with the conjugated diene polymer, r and m are preferably 0 or 1.

[0058] A 1 When A is the above-mentioned monovalent functional group, 1 At least one atom selected from nitrogen, phosphorus, oxygen, sulfur and silicon and A 2 The at least one atom selected from nitrogen, phosphorus, oxygen, sulfur and silicon is preferably not bonded to active hydrogen, and is more preferably protected by a protecting group (e.g., a trisubstituted hydrocarbylsilyl group). It should be noted that in this specification, active hydrogen refers to a hydrogen atom bonded to an atom other than a carbon atom, preferably a hydrogen atom with a lower bond energy than the carbon-hydrogen bond of polymethylene. A protecting group refers to 1 、A 2 A functional group that is converted into an inactive functional group with respect to a polymerization active terminal. The (thio)epoxy group includes an epoxy group and a thioepoxy group.

[0059] A 1 Can be used Salt generator formation Ionic group. Compound (C2) has such a group (A 1 ), which can impart excellent shape retention to the hydrogenated conjugated diene polymer.

[0060] As A 1 Specific examples include a nitrogen-containing group in which two hydrogen atoms of a primary amino group are replaced by two protecting groups, a nitrogen-containing group in which one hydrogen atom of a secondary amino group is replaced by one protecting group, a tertiary amino group, an imino group, a pyridyl group, a phosphorus-containing group in which two hydrogen atoms of a primary phosphino group are replaced by two protecting groups, a phosphorus-containing group in which one hydrogen atom of a secondary phosphino group is replaced by one protecting group, a tertiary phosphino group, an epoxy group, a group in which a hydrogen atom of a hydroxyl group is protected by a protecting group, a thioepoxy group, a sulfur-containing group in which a hydrogen atom of a thiol group is replaced by a protecting group, a hydrocarbyloxycarbonyl group, and the like. Among these, a group having a nitrogen atom is preferred from the viewpoint of good affinity with silica, and a group comprising a nitrogen-containing group in which one hydrogen atom of a tertiary amino group or a secondary amino group is replaced by one protecting group, or a nitrogen-containing group in which two hydrogen atoms of a primary amino group are replaced by two protecting groups is more preferred.

[0061] In the above formula (11), L 2 and L 3Examples of the alkylene group having 1 to 20 carbon atoms include a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms. 9 and R 10 Examples of the hydrocarbon group include a linear or branched alkyl group having 1 to 4 carbon atoms and a cycloalkyl group having 3 or 4 carbon atoms. The (thio)carbonyl group includes a carbonyl group and a thiocarbonyl group, the (thio)carbonyloxy group includes a carbonyloxy group and a thiocarbonyloxy group, the (thio)isocyanate group includes an isocyanate group and a thioisocyanate group, the (thio)formyl group includes a formyl group and a thioformyl group, and the (thio)carboxylate group includes a carboxylate group and a thiocarboxylate group.

[0062] In the above formula (12), Z 1 It is a divalent or trivalent group having 1 to 20 carbon atoms which may contain a nitrogen atom, and preferably contains a nitrogen atom. 5 and L 6 Examples of the alkylene group having 1 to 20 carbon atoms include a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an arylene group having 6 to 20 carbon atoms. 13 and R 14 The hydrocarbon group includes a linear or branched alkyl group having 1 to 4 carbon atoms and a cycloalkyl group having 3 or 4 carbon atoms.

[0063] Preferred specific examples of compound (C2) include compounds represented by formula (9) such as N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-(4-trimethylsilyl-1-piperazinyl)propylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyltriethoxysilane. Examples of compounds represented by formula (10) include 2,2-dimethoxy-1-(3-trimethoxysilyl)-1-(4-trimethylsilyl)-1-piperazinyl)propylmethyldimethoxysilane, and 3-glycidoxypropyltriethoxysilane. 1-(2-(2,2-dimethoxy-1,2-azasilylcyclopentane-1-yl)-N,N-diethylethane-1-amine, 2-(2,2-dimethoxy-1,2-azasilylcyclopentane-1-yl)-N,N-dimethylethane-1-amine, 3-(2,2-dimethoxy-1,2-azasilylcyclopentane-1-yl)-N,N-diethylpropane-1-amine, etc.

[0064] In addition, as preferred specific examples of compound (C2), examples of the compound represented by the above formula (11) include N,N-bis(trimethoxysilylpropyl)aminopropyl-3-(1-imidazole), N,N-bis(triethoxysilylpropyl)aminopropyl-3-(1-imidazole), N,N-bis(trimethoxysilylpropyl)aminopropylmethyldiethylsilane, N,N,N-tris(triethoxysilylpropyl)amine, and N,N,N',N'-tetrakis(3-triethoxysilylpropyl)-1,3-diaminopropane. Examples of the compound represented by the above formula (12) include compounds represented by the following formulas (M-1) to (M-4).

[0065]

[0066] (In formula (M-1), R 15 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and n5 is an integer of 1 to 10);

[0067] Examples of compounds other than the above compounds include 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, etc. Compound (C2) may be used alone or in combination of two or more.

[0068] The above-mentioned terminal modification reaction can be carried out, for example, by solution reaction. The solution reaction can be carried out using a solution of unreacted monomers after the polymerization reaction in the above-mentioned polymerization step is completed, or the conjugated diene polymer contained in the solution can be separated and dissolved in a suitable solvent such as cyclohexane. In addition, the terminal modification reaction can be carried out using any one of batch and continuous methods. At this time, the method for adding compound (C2) is not particularly limited, and a method for one-time addition, a method for adding in portions, a method for continuous addition, etc. can be cited.

[0069] The amount of compound (C2) used in the terminal modification reaction can be appropriately set depending on the type of compound used in the reaction, and is preferably 0.1 molar equivalent or more, more preferably 0.3 molar equivalent or more, relative to the metal atoms in the polymerization initiator that participate in the polymerization reaction. When the amount of compound (C2) used is 0.1 molar equivalent or more, the modification reaction can proceed sufficiently, and the dispersibility of silica can be appropriately improved.

[0070] The temperature of the terminal modification reaction is generally the same as that of the polymerization reaction, preferably -20 to 150°C, more preferably 0 to 120°C, and particularly preferably 20 to 100°C. If the modification reaction temperature is low, the viscosity of the modified conjugated diene polymer tends to increase. On the other hand, if the modification reaction temperature is high, the polymerization-active terminals are more likely to be deactivated. The reaction time of the modification reaction is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

[0071] (Hydrogenation reaction)

[0072] The hydrogenated conjugated diene polymer disclosed herein can be obtained by hydrogenating the modified or unmodified conjugated diene polymer obtained above. As long as the method and conditions of the hydrogenation reaction can obtain a conjugated diene polymer with a desired hydrogenation rate, any method and conditions can be adopted. As examples of these hydrogenation methods, there are the following methods: a method using a catalyst with an organometallic compound of titanium as the main component as a hydrogenation catalyst, a method using a catalyst composed of an organic compound of iron, nickel, cobalt and an organometallic compound such as an alkyl aluminum, a method using an organic complex of an organometallic compound such as ruthenium, rhodium, etc., a method using a catalyst having a metal such as palladium, platinum, ruthenium, cobalt, nickel, etc. supported on a carrier such as carbon, silica, aluminum oxide, etc. Among various methods, the method of using a titanium organometallic compound alone or a homogeneous catalyst composed of a titanium organometallic compound and an organometallic compound of lithium, magnesium, or aluminum (Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-37970) to carry out hydrogenation under mild conditions of low pressure and low temperature is industrially preferred. In addition, the selectivity for hydrogenation of the double bonds of butadiene is also high, which is suitable for the purpose of the present disclosure.

[0073] The hydrogenation of the modified conjugated diene polymer is carried out in a solvent that is inactive to the catalyst and in which the conjugated diene polymer is soluble. Preferred solvents include aliphatic hydrocarbons such as n-pentane, n-hexane, and n-octane; alicyclic hydrocarbons such as cyclohexane and cycloheptane; aromatic hydrocarbons such as benzene and toluene; and ethers such as diethyl ether and tetrahydrofuran, either alone or as a main component.

[0074] The hydrogenation reaction is generally carried out by maintaining the conjugated diene polymer under hydrogen or an inert atmosphere at a predetermined temperature, adding a hydrogenation catalyst with or without stirring, and then introducing hydrogen gas and pressurizing it to a predetermined pressure. An inert atmosphere refers to an atmosphere that does not react with the participants in the hydrogenation reaction, and examples thereof include helium, neon, and argon. Air and oxygen are not preferred because they deactivate the catalyst by oxidizing the catalyst. In addition, nitrogen acts as a catalyst poison during the hydrogenation reaction, reducing the hydrogenation activity, and is therefore not preferred. In particular, an atmosphere containing only hydrogen in the hydrogenation reactor is most preferred.

[0075] The hydrogenation reaction process for obtaining the hydrogenated conjugated diene polymer can use any one of a batch process, a continuous process, a combination thereof. In addition, when a diaryltitanium compound is used as the hydrogenation catalyst, it can be directly added to the reaction solution alone or as a solution in an inactive organic solvent. When the catalyst is used in the form of a solution, the inactive organic solvent used can use various solvents that do not react with the participants in the hydrogenation reaction. A solvent identical to the solvent used in the hydrogenation reaction is preferred. In addition, the amount of catalyst added is 0.02 to 20 millimoles per 100 g of the conjugated diene polymer before hydrogenation.

[0076] For the hydrogenated conjugated diene polymer of the present disclosure, a of the above mathematical formula (i) (i.e., a = (p + (0.5 x r)) / (p + q + (0.5 x r) + s)) is 0.70 to 0.99. By making a 0.70 or greater, a crosslinked rubber having high strength and excellent wear resistance and crack growth resistance can be obtained. From such a reason, a is preferably 0.75 or greater, more preferably 0.80 or greater, and particularly preferably 0.90 or greater. Note that a of the above mathematical formula (i) corresponds to the hydrogenation rate of the hydrogenated conjugated diene polymer. For example, when a is 0.70, the hydrogenation rate of the hydrogenated conjugated diene polymer is 70%. The hydrogenation rate in the hydrogenated conjugated diene polymer can be adjusted by the time of the hydrogenation reaction, etc. The hydrogenation rate can be determined by H-NMR. Note that when the (A) polymer is a polymer obtained by copolymerizing a diene monomer with a non-conjugated olefin, the value of a can be adjusted by changing the copolymerization monomer ratio. 1 H-NMR. Note that when the (A) polymer is a polymer obtained by copolymerizing a diene monomer with a non-conjugated olefin, the value of a can be adjusted by changing the copolymerization monomer ratio.

[0077] A preferred method for obtaining the hydrogenated conjugated diene polymer of the present disclosure is to perform solution polymerization of a monomer containing butadiene in the presence of an alkali metal compound, directly use the obtained polymer solution for the modification step, and then subject to the hydrogenation step, which is industrially useful. At this time, the hydrogenated conjugated diene polymer is obtained by removing the solvent from the above obtained solution and isolating the polymer. The isolation of the polymer can be performed by, for example, a known desolventization method such as stripping, and a drying operation such as heat treatment.

[0078] From the viewpoint of being able to further improve the low fuel consumption performance of the crosslinked body obtained using the rubber composition, the (A) polymer preferably has one or more functional groups selected from the group consisting of an amino group, a nitrogen-containing heterocyclic group, a phosphine group, a hydroxyl group, a thiol group, and a hydrocarbyloxysilyl group, and more preferably has one or more functional groups selected from the group consisting of an amino group, a nitrogen-containing heterocyclic group, and a hydrocarbyloxysilyl group. From the viewpoint of being able to further improve the improvement effect on the low fuel consumption performance, it is particularly preferable that these functional groups be introduced to the terminal of the (A) polymer.

[0079] <Thermoplastic Resin>

[0080] As the thermoplastic resin contained in the rubber composition of the present disclosure (hereinafter, also referred to as "(B) resin"), at least one selected from the group consisting of a styrene-based resin, polyethylene, a C5-based resin, a C9-based resin, a C5 / C9-based resin, a dicyclopentadiene-based resin, and an alkylphenol-based resin is preferable from the viewpoint of obtaining a crosslinked rubber more excellent in various properties such as strength, wear resistance, and crack growth resistance. As the thermoplastic resin, one kind can be used alone, or two or more kinds can be used in combination.

[0081] Here, the styrene-based resin is a polymer obtained using a styrene-based monomer, and a polymer having 20% by mass or more of structural units derived from the styrene-based monomer with respect to the total amount of monomer units possessed by the styrene-based resin is preferable. As the styrene-based monomer, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, a-methylstyrene, p-methoxystyrene, p-t-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and the like can be given. Among these, the styrene-based monomer is preferably at least one of styrene and a-methylstyrene.

[0082] The styrene-based resin can be a homopolymer obtained by polymerizing one kind of styrene-based monomer, or can be a copolymer obtained by copolymerizing two or more kinds of styrene-based monomers. In addition, the styrene-based resin can be a copolymer obtained using a styrene-based monomer and another monomer copolymerizable with the styrene-based monomer. As the other monomer, acrylonitrile, methacrylonitrile, and the like acrylonitrile-based monomers, acrylic acid, methacrylic acid, and the like unsaturated carboxylic acids; methyl acrylate, methyl methacrylate, and the like unsaturated carboxylic acid esters; chloroprene, butadiene isoprene, and the like diene-based monomers; 1-butene, 1-pentene, and the like olefin-based monomers; maleic anhydride and the like a, β-unsaturated carboxylic acids or anhydrides thereof, and the like can be given.

[0083] The softening point of the styrene-based resin is preferably 30°C or higher, more preferably 60°C or higher, and further preferably 80°C or higher. If the softening point is 30°C or higher, there is a tendency that an improvement effect on crack growth resistance in the crosslinked rubber is easily obtained. In addition, the softening point of the styrene-based resin is preferably 160°C or lower, more preferably 130°C or lower, and further preferably 100°C or lower. If the softening point is 160°C or lower, there is a tendency that the dispersibility of the resin becomes good, and the crack growth resistance, wear resistance, and breaking strength are easily improved. Note that, in the present disclosure, the softening point of the styrene-based resin is a value measured using a ring and ball softening point measuring device according to the method prescribed in JIS K6220-1:2015, and is the temperature at which the sample softens and the ball placed under the sample falls onto the bottom plate.

[0084] As the styrene-based resin, a block polymer (thermoplastic elastomer) having a conjugated diene-based polymer block as a soft segment and a polystyrene-based block as a hard segment can also be used. When such a block polymer is used, the improvement effect of the crack growth resistance can be further improved, and thus is preferred. Note that in the conjugated diene-based polymer block possessed by the above block polymer, a part of the carbon-carbon double bonds in the structural units derived from the conjugated diene compound can be hydrogenated.

[0085] As the conjugated diene compound constituting the above conjugated diene-based polymer block, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-l,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and the like can be given. As the conjugated diene compound, one kind can be used alone or two or more kinds can be used in combination. Among these, at least one of 1,3-butadiene and isoprene is preferred as the conjugated diene compound. The content ratio of the conjugated diene unit in the block polymer is preferably 20% by mass or more, and more preferably 30% by mass or more. In addition, the content ratio of the conjugated diene unit is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0086] From the viewpoint of further improving the breaking strength, the content ratio of the polystyrene-based block in the above block polymer is preferably 20% by mass or more. In addition, the content ratio of the polystyrene-based block is preferably 80% by mass or less, and more preferably 70% by mass or less. Note that the respective content ratios of the polystyrene-based block, the conjugated diene-based polymer block, and the conjugated diene unit in the block polymer can be calculated from the integral ratio of the H-NMR spectrum. 1 The integral ratio of the H-NMR spectrum was calculated.

[0087] As specific examples of the above block polymer, styrene-butadiene block copolymer, styrene-isoprene block copolymer, epoxidized styrene-butadiene block copolymer, and a block copolymer obtained by hydrogenating a part of the conjugated diene-based polymer block possessed by the styrene-butadiene block copolymer or the styrene-isoprene block copolymer, and the like can be given. In more detail, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-butadiene-styrene block copolymer (SBBS), and epoxidized styrene-butadiene-styrene block copolymer, and hydrogenated products of these copolymers, and the like can be given. As the above block polymer, from the viewpoint of easy crosslinking, among these, SBS or SIS having a conjugated diene-based polymer block in which the soft segment is not hydrogenated, or epoxidized styrene-butadiene-styrene block copolymer can be preferably used.

[0088] Examples of polyethylene include low-density polyethylene (LDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE). C5-based resins are solid polymers (C5-based synthetic petroleum resins) obtained by polymerizing C5 fractions using a Friedel-Crafts catalyst (e.g., AlCl3, BF3). Specific examples of C5-based resins include copolymers primarily composed of isoprene, cyclopentadiene, 1,3-pentadiene, and 1-pentene, copolymers of 2-pentene and dicyclopentadiene, and polymers primarily composed of 1,3-pentadiene.

[0089] C9-based resins are solid polymers (C9-based synthetic petroleum resins) obtained by polymerizing C9 fractions using a Friedel-Crafts catalyst (AlCl3, BF3, etc.). Specific examples of C9-based resins include copolymers with indene, methylindene, vinyltoluene, etc. as main components. C5 / C9-based resins are solid polymers (C5 / C9-based synthetic petroleum resins) obtained by polymerizing C5 to C9 fractions using a Friedel-Crafts catalyst (AlCl3, BF3, etc.). Specific examples of C5 / C9-based resins include copolymers with vinyltoluene, indene, etc. as main components. From the viewpoint of compatibility with rubber components, C5 / C9-based resins are preferably resins with fewer components above C9. Specifically, in C5 / C9-based resins, the components above C9 in the total amount of the resin are preferably less than 50% by mass, and more preferably less than 40% by mass.

[0090] Dicyclopentadiene resins are petroleum resins made from dicyclopentadiene in the C5 fraction as a main raw material. Specific examples of dicyclopentadiene resins include the "MARUKAREZ M" series (M-890A, M-845A, M-990A, etc.) from Maruzen Petrochemical Co., Ltd. Examples of alkylphenol resins include alkylphenol-acetylene resins such as p-tert-butylphenol-acetylene resin and alkylphenol-formaldehyde resins with a low degree of polymerization.

[0091] (B) resin is preferably 1 part by mass or more. By incorporating 1 part by mass or more of the (B) resin, the improvement effects of the abrasion resistance, the breaking strength, and the crack growth resistance brought about by the addition of the (B) resin can be sufficiently improved in the crosslinked body obtained using the rubber composition, and thus the (B) resin is preferably incorporated in a proportion of 3 parts by mass or more, and further preferably 7 parts by mass or more, relative to 100 parts by mass of the rubber component contained in the rubber composition. In addition, from the viewpoint of maintaining the various properties of the rubber composition in a good state, the (B) resin is preferably incorporated in a proportion of 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 25 parts by mass or less, relative to 100 parts by mass of the rubber component contained in the rubber composition. Note that, as the (B) resin, one kind can be used alone, or two or more kinds can be used in combination. In the present specification, the "rubber component" contained in the rubber composition refers to a polymer that can obtain a cured product that exhibits rubber elasticity by thermal curing. The cured product exhibits a property of deforming greatly (for example, deforming to 2 times or more in length when stretched at room temperature) with a small force at room temperature, and quickly returning to almost the original shape when the force is removed.

[0092] The rubber composition of the present disclosure contains 60 to 95 mass% of the (A) polymer and 5 to 40 mass% of the (B) resin, relative to the total amount of the (A) polymer and the (B) resin. By incorporating the (A) polymer and the (B) resin in the above range, the improvement effects of the abrasion resistance, the breaking strength, and the crack growth resistance can be balanced and sufficiently obtained. From the aspect of higher improvement effects of the breaking strength and the abrasion resistance, the (A) polymer and the (B) resin are preferably incorporated in a proportion of 80 to 95 mass% of the (A) polymer and 5 to 20 mass% of the (B) resin, and more preferably in a proportion of 86 to 93 mass% of the (A) polymer and 7 to 14 mass% of the (B) resin.

[0093] <crosslinking agent>

[0094] The crosslinked rubber of the present embodiment is a crosslinked rubber obtained by heat treatment. The kind of the crosslinking agent contained in the rubber composition for the heat treatment is not particularly limited. As specific examples of the crosslinking agent, there are organic peroxide, phenol aldehyde resin, sulfur, sulfur compound, p-benzoquinone, derivative of p-benzoquinone dioxime, bismaleimide compound, epoxy compound, silane compound, amino resin, polyol, polyamine, triazine compound, metal soap, and the like. Among these, at least one selected from the group consisting of organic peroxide, phenol aldehyde resin, and sulfur is preferable. The crosslinking agent can be used alone or in combination with two or more kinds.

[0095] As the organic peroxide, for example, 1, 3-bis (tert-butylperoxyisopropyl) benzene, 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexyne-3, 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexene-3, 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane, 2, 2'-bis (tert-butylperoxy) p-isopropylbenzene, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxide, and the like can be given.

[0096] As the phenol resin, for example, a para-substituted phenol-based compound represented by the following general formula (8), an ortho-substituted phenol-aldehyde condensate, a meta-substituted phenol-aldehyde condensate, a brominated alkyl phenol-aldehyde condensate, and the like can be given. Among them, the para-substituted phenol-based compound is preferred.

[0097]

[0098] In the above formula (8), X is a hydroxyl group, a haloalkyl group, or a halogen atom, R is a saturated hydrocarbon group having 1 to 15 carbon atoms, and n is an integer of 0 to 10. Note that the para-substituted phenol-based compound can be obtained by condensation reaction of a para-substituted phenol with an aldehyde (preferably formaldehyde) in the presence of a base catalyst.

[0099] As the commercially available phenol resin, for example, "Tackirol 201" (alkyl phenol formaldehyde resin, manufactured by Takigawa Chemical Industrial Co., Ltd.), "Tackirol 250-I" (brominated alkyl phenol formaldehyde resin having a bromination rate of 4%, manufactured by Takigawa Chemical Industrial Co., Ltd.), "Tackirol 250-III" (brominated alkyl phenol formaldehyde resin, manufactured by Takigawa Chemical Industrial Co., Ltd.), "PR-4507" (manufactured by Gun Ei Chemical Industry Co., Ltd.), "ST137X" (manufactured by Rohm & Haas), "SUMILITERESIN PR-22193" (manufactured by Sumitomo Durez), "TAMANOL 531" (manufactured by Arakawa Chemical Industries, Ltd.), "SP1059", "SP1045", "SP1055", "SP1056" (all of which are manufactured by Schenectady), and "CRM-0803" (manufactured by Showa Union Synthesis) can be given. Among them, "Tackirol 201" is preferably used.

[0100] The crosslinking agent is preferably used in an amount of 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and further preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total of the rubber components contained in the rubber composition for producing the crosslinked rubber.

[0101] When an organic peroxide is used as the crosslinking agent, the amount of the organic peroxide used is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the total amount of the rubber components contained in the rubber composition used to produce the crosslinked rubber. If the amount of the organic peroxide exceeds 10 parts by mass, the crosslinking degree becomes excessively high, the moldability decreases, and there is a tendency for the mechanical properties of the crosslinked rubber obtained to decrease. On the other hand, if the amount of the organic peroxide is less than 0.05 parts by mass, there is a tendency for the crosslinking degree to be insufficient, and the rubber elasticity and mechanical strength of the crosslinked rubber obtained to decrease.

[0102] In addition, when a phenol resin is used as the crosslinking agent, the amount of the phenol resin used is preferably 0.2 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the total amount of the rubber components contained in the rubber composition used to produce the crosslinked rubber. If the amount of the phenol resin exceeds 10 parts by mass, there is a tendency for the moldability to decrease. On the other hand, if the amount of the phenol resin is less than 0.2 parts by mass, there is a tendency for the crosslinking degree to be insufficient, and the rubber elasticity and mechanical strength of the crosslinked rubber obtained to decrease.

[0103] When sulfur is used as the crosslinking agent, the amount of the sulfur used is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass of the total amount of the rubber components contained in the rubber composition used to produce the crosslinked rubber.

[0104] If at least either a crosslinking aid or a crosslinking accelerator is used together with the crosslinking agent, the crosslinking reaction can be smoothly performed, and a uniform crosslinking can be formed, and thus is preferred. When an organic peroxide is used as the crosslinking agent, as the crosslinking aid, sulfur, sulfur compounds (powdered sulfur, colloidal sulfur, precipitated sulfur, insoluble sulfur, surface-treated sulfur, dipentamethylene thiodiammonium tetrasulfide, etc.), oxime compounds (p-quinone monoxime, p,p'-dibenzoylquinone monoxime, etc.), multifunctional monomers (ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, diallyl phthalate, tetraallyloxyethane, triallyl cyanurate, N,N'-m-phenylene bismaleimide, N,N'-benzylidene bismaleimide, maleic anhydride, divinylbenzene, zinc di(meth)acrylate, etc.), and the like are preferably used. Among these, p,p'-dibenzoylquinone monoxime, N,N'-m-phenylene bismaleimide, and divinylbenzene are preferred. One of these can be used alone, or two or more of these can be used in combination. Note that N,N'-m-phenylene bismaleimide exhibits the effect of a crosslinking agent, and thus can be used alone as a crosslinking agent.

[0105] The amount of the cross-linking aid used when using an organic peroxide as the cross-linking agent is preferably 10 parts by mass or less, and more preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the total amount of the rubber components contained in the mixture. If the amount of the cross-linking aid exceeds 10 parts by mass, there is a tendency for the cross-linking degree to become excessively high, the moldability to decrease, and the mechanical properties of the cross-linked rubber to decrease.

[0106] When using a phenol resin as the cross-linking agent, it is preferable to use a metal halide (stannous chloride, ferric chloride, etc.), an organic halide (chlorinated polypropylene, brominated butyl rubber, chloroprene rubber, etc.), or the like as a cross-linking accelerator, because it is possible to adjust the cross-linking speed. In addition, it is further preferable to use a metal oxide such as zinc oxide, a dispersant such as stearic acid, or the like in addition to the cross-linking accelerator.

[0107] In the rubber composition of the present disclosure, in addition to the above-described (A) polymer, a rubber component (hereinafter also referred to as "another rubber component") that is different from the (A) polymer can be blended within a range that does not impair the effects of the present disclosure. The kind of the other rubber component is not particularly limited, and examples include butadiene rubber (BR, for example, high-cis BR in which the cis-1,4 bond is 90% or more, BR containing syndiotactic-1,2-polybutadiene (SPB), and the like), styrene butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), and the like, and more preferably at least one selected from NR, BR, and SBR. When the other rubber component is used, the blending ratio of the other rubber component is preferably 70 parts by mass or less, and more preferably 50 parts by mass or less, relative to 100 parts by mass of the total amount of the rubber components ((A) polymer and other rubber component) contained in the rubber composition.

[0108] In the rubber composition of the present disclosure, as the filler, various reinforcing fillers such as carbon black, silica, clay, calcium carbonate, and the like can be used. Carbon black, silica, or a combination of carbon black and silica is preferable. From the aspect of the static / dynamic ratio, silica is preferable, and from the aspect of the strength of the rubber composition and the cross-linked rubber, carbon black is preferable. As the silica, for example, wet-process silica (hydrous silicic acid), dry-process silica (anhydrous silicic acid), colloidal silica, and the like can be given, and wet-process silica is preferable. As the carbon black, for example, furnace black, acetylene black, thermal black, channel black, graphite, and the like can be given, and furnace black is preferable.

[0109] The blending amount of the filler can be appropriately determined according to the purpose of use, and for example, 5 to 150 parts by mass relative to 100 parts by mass of the rubber components blended in the rubber composition. The total amount of the silica and the carbon black in the rubber composition is preferably 20 to 130 parts by mass, and more preferably 25 to 110 parts by mass, relative to 100 parts by mass of the total amount of the rubber components contained in the rubber composition.

[0110] In the rubber composition of the present disclosure, in addition to the above-mentioned components, various additives generally used in rubber compositions for obtaining crosslinked rubber for various uses such as tires, hoses, vibration isolators, belts, and the like can be incorporated. As the additives, for example, anti-aging agents, zinc white, stearic acid, softening agents, sulfur, vulcanization accelerators, and the like can be mentioned. The incorporation ratio thereof can be appropriately selected depending on the kind of the additive within a range not impairing the effects of the present disclosure.

[0111] Crosslinked body and tire

[0112] Crosslinking step

[0113] When the rubber composition of the present disclosure is made into a rubber molded product, generally, after the rubber composition is molded into a prescribed shape, crosslinking treatment is performed. The production of the rubber molded product can be performed in accordance with a conventional method. For example, the production of a tire is performed by mixing the above-mentioned rubber composition with a roll, a kneader, or the like mixing machine and molding into a prescribed shape, and the obtained molded product is vulcanized and molded in accordance with a conventional method by arranging on the outside, thereby forming one or both of a tread and a side, and obtaining a pneumatic tire. Note that, in obtaining the rubber molded product, as the crosslinking agent and the crosslinking aid, the above-mentioned crosslinking agent and crosslinking aid can be used.

[0114] The crosslinked rubber configured as above exhibits high strength and excellent wear resistance, and is excellent in crack growth resistance, and thus can be applied to various rubber molded products. Specifically, it can be used as a material for a tread and a side of a tire; a shock absorbing rubber for industrial machines, equipment, and the like; various hoses such as a diaphragm, a roll, a radiator hose, an air hose, and a hose protector; sealing materials such as a gasket, a packing, a sealing strip, an O-ring, and an oil seal; a belt such as a power transmission belt; and a material for a liner, a dust cover, and the like. Among these, it can be suitably used as a tire member, a vibration isolator member, and a belt member, and can be particularly suitably used as a tire member.

[0115] Examples

[0116] Hereinafter, the present disclosure will be specifically described based on examples, but the present disclosure is not limited to these examples. Note that, in the examples and comparative examples, "parts" and "%" are on a mass basis unless otherwise specified. Hereinafter, the measurement method of various physical property values is shown.

[0117] [Styrene bond content (%)] : Found by 500 MHz 1 H-NMR.

[0118] [1,2-vinyl content (%)] : Found by 500 MHz 1 H-NMR.

[0119] [Modified molecular weight]: Calculated from the retention time at the top of the maximum peak of the GPC curve obtained using gel permeation chromatography (GPC) (HLC-8120GPC (trade name) (manufactured by Tosoh Corporation)) in terms of polystyrene.

[0120] (GPC conditions)

[0121] Column: Two of trade name "GMHXL" (manufactured by Tosoh Corporation)

[0122] Column temperature: 40°C

[0123] Mobile phase: Tetrahydrofuran

[0124] Flow rate: 1.0 ml / minute

[0125] Sample concentration: 10 mg / 20 ml

[0126] [Mooney viscosity]: Calculated according to JIS K6300-1:2013, using an L rotor under conditions of preheating for 1 minute, rotor running time of 4 minutes, and temperature of 100°C.

[0127] [Hydrogenation rate (%)] and [α]: Calculated by 500 MHz1H-NMR. 1 H-NMR.

[0128] <Manufacture of high-saturated diene polymer>

[0129] <Manufacture of hydrogenation catalyst>

[0130] [Manufacturing Example 1: Synthesis of Catalyst A]

[0131] A 1L three-necked flask equipped with a stirrer, a dropping funnel was replaced with dry nitrogen, and anhydrous tetrahydrofuran 200 ml and tetrahydrofurfuryl alcohol 0.2 moles were added. Thereafter, n-butyllithium / cyclohexane solution (0.2 moles) was added dropwise to the three-necked flask at 15°C to obtain a tetrahydrofurfuryloxy lithium tetrahydrofuran solution.

[0132] Next, a 1L three-necked flask equipped with a stirrer, a dropping funnel was replaced with dry nitrogen, and bis(η5-cyclopentadienyl) titanium dichloride 49.8 g (0.2 moles) and anhydrous tetrahydrofuran 250 ml were added. Then, the tetrahydrofurfuryloxy lithium tetrahydrofuran solution obtained by the method described above was added dropwise over about 1 hour with stirring at room temperature. After about 2 hours, the reddish-brown liquid was filtered, and the insoluble portion was washed with dichloromethane.

[0133] Thereafter, the filtrate and the washing liquid were combined, and the solvent was removed under reduced pressure, whereby a catalyst A [bis(η5-cyclopentadienyl) titanium (tetrahydrofurfuryloxy) chloride] (also referred to as "[chlorobis(2,4-cyclopentadienyl) titanium (IV) tetrahydrofurfuryl alcohol salt]") was obtained. Note that the yield was 95%.

[0134] <Manufacture of hydrogenated conjugated diene polymer>

[0135] [Manufacture Example 2: Synthesis of hydrogenated conjugated diene rubber A]

[0136] In a nitrogen-substituted 10 liter high-pressure autoclave reactor, cyclohexane 5000 g, tetrahydrofuran 150.0 g, styrene 250 g, and 1,3-butadiene 730 g were charged. After adjusting the temperature of the contents of the reactor to 10°C, a solution containing n-butyllithium (11.60 mmol) in cyclohexane was added to start the polymerization. The polymerization was carried out under heat-insulating conditions, and the maximum temperature reached 85°C.

[0137] At the time when the polymerization conversion reached 99%, 20 g of butadiene was added, and further polymerization was carried out for 5 minutes, whereby a reaction liquid containing a polymer was obtained. To the obtained reaction liquid, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane 8.5 g was added, and the reaction was carried out for 30 minutes.

[0138] Next, catalyst A 0.32 g, tetrachlorosilane 0.39 g were added, and the reaction was carried out for 55 minutes while maintaining the hydrogen pressure at 1.0 MPa. After the reaction, the reaction liquid was returned to normal temperature and normal pressure and was extracted from the reaction vessel, whereby a polymer solution was obtained.

[0139] Next, an aqueous solution (temperature: 80°C) adjusted to pH 8.5 using ammonia as a pH adjuster (pH at 80°C measured by a glass electrode method, and the same applies hereinafter) was placed in a desolventizing tank, and further, the above polymer solution (in a ratio of 100 parts by mass of the polymer solution to 200 parts by mass of the above aqueous solution) was added. Desolventization was carried out by 2 hours of stripping (vapor temperature: 190°C) at a temperature of the liquid phase of the desolventizing tank: 95°C, and drying was carried out using a hot roll adjusted to 110°C, whereby hydrogenated conjugated diene rubber A was obtained. The properties of the obtained hydrogenated conjugated diene rubber A are shown in Table 1 below.

[0140] <Manufacture of conjugated diene polymer>

[0141] [Manufacture Example 3: Synthesis of conjugated diene rubber S]

[0142] A 5-liter high-pressure autoclave reactor was charged with cyclohexane 2750 g, tetrahydrofuran 50.0 g, styrene 125 g, and 1,3-butadiene 365 g. After the temperature of the reactor contents was adjusted to 10°C, polymerization was initiated by adding a cyclohexane solution containing n-butyllithium (5.80 mmol). The polymerization was carried out under heat-insulating conditions, with the maximum temperature reaching 85°C.

[0143] At the point when the polymerization conversion reached 99%, 10 g of butadiene was added, and further polymerization was carried out for 5 minutes, to obtain a reaction liquid containing a polymer. To the obtained reaction liquid was added N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane 4.25 g, and the reaction was carried out for 30 minutes. To the obtained polymer solution was added 2,6-di-tert-butyl-p-cresol 2.0 g. Subsequently, desolventization was carried out using hot water adjusted to pH = 9 with sodium hydroxide for stripping, and the rubber was dried using a hot roll adjusted to 110°C, to obtain a conjugated diene-based rubber S. The properties of the obtained conjugated diene-based rubber S are shown in Table 1 below.

[0144] [Table 1]

[0145]

[0146] <Manufacture of Rubber Composition and Evaluation of Properties>

[0147] [Examples 1 to 11 and Comparative Examples 1 to 3]

[0148] Using a PLASTOMILL (content volume 250 cc) equipped with a temperature control device, as a first step of mixing, a hydrogenated conjugated diene-based rubber A, a conjugated diene-based rubber S, a natural rubber, a thermoplastic resin, silica, carbon black, a silane coupling agent, stearic acid, an anti-aging agent, and zinc oxide were mixed in accordance with the compounding recipe of Table 2 below, under conditions of a fill rate of 72% and a rotation speed of 60 rpm. Subsequently, as a second step of mixing, the obtained mixture was cooled to room temperature, and sulfur and a vulcanization accelerator were added and mixed. This was shaped, and vulcanization was carried out for a prescribed time using a press vulcanizer at 160°C. The following (1) to (3) were carried out using the rubber composition before vulcanization or the vulcanized rubber.

[0149] (1) Breaking strength: No. 3 dumbbell-shaped test pieces composed of test pieces of vulcanized rubber for testing were prepared as test pieces for evaluation in accordance with JIS K6251:2010. A tensile testing machine (model name "AG-2000", manufactured by Shimadzu Corporation) was used to stretch the test pieces at a load speed of 500 mm / minute, and the breaking strength (TB) was calculated. The value was expressed as an index with Comparative Example 1 set to 100, and the larger the value, the higher the strength.

[0150] (2) Abrasion resistance: Using vulcanized rubber as a test sample, the abrasion resistance was measured at 25°C with a load of 10 N using a DIN abrasion tester (manufactured by Toyo Seiki Co., Ltd.) in accordance with JIS K 6264-2:2005. The value was expressed as an index in which Comparative Example 1 was taken as 100, and the larger the value, the better the abrasion resistance.

[0151] (3) Crack growth resistance: After the rubber composition was molded into a sheet shape by calendering, the sheet was subjected to vulcanization treatment at 160°C for a prescribed time using a press vulcanizer, thereby producing a sheet composed of crosslinked rubber having a thickness of 2 mm. By subjecting the obtained sheet to blanking processing, a test piece composed of Type IV dumbbell described in ASTM D638 was produced. At this time, the sheet was subjected to blanking processing in such a manner that the long side direction of the dumbbell became the grain direction of the sheet, and a crack extending in the reverse grain direction was formed at the central position in the long side direction of the dumbbell. The obtained test piece was subjected to constant elongation fatigue testing under conditions of an elongation rate of 100%, a measurement temperature of 23°C, and a rotation speed of 300 cpm, and the number of cycles until the test piece broke was measured. The value was expressed as an index in which Comparative Example 1 was taken as 100, and the larger the value, the better the crack growth resistance.

[0152] The results of the property evaluation of Examples 1 to 11 and Comparative Examples 1 to 3 are shown in Table 2 below.

[0153] [Table 2]

[0154]

[0155] In Table 2, the details of each component used are as follows.

[0156] Hydrogenated SBR: hydrogenated conjugated diene rubber A

[0157] SBR: conjugated diene rubber S

[0158] SIS: JSR SIS5250 (styrene content 20%) manufactured by JSR Corporation

[0159] SIBS: SIBSTAR 102T (styrene content 23%) manufactured by Kaneka Corporation

[0160] Epoxy SBS: EPOFRIEND A102 (styrene content 40%) manufactured by Daicel Chemical Industries, Ltd.

[0161] Polyethylene: KS340T manufactured by Japan Polyethylene Corporation

[0162] AS resin: SANREX SAN-C (styrene content 73%) manufactured by Techno-UMG Corporation

[0163] C5 / C9-based resin: T-REZ PR802 manufactured by JXTG Energy Co.

[0164] Carbon black: Dia Black N339 manufactured by Mitsubishi Chemical Co.

[0165] Silica: Nipsil AQ manufactured by Tosoh Silica Co.

[0166] Silane coupling agent: Si69 manufactured by Evonik Co.

[0167] Anti-aging agent: NOCRAC 810NA manufactured by Ono Pharmaceutical Co.

[0168] Vulcanization accelerator CZ: NOCCELER CZ manufactured by Ono Pharmaceutical Co.

[0169] Vulcanization accelerator D: NOCCELER D manufactured by Ono Pharmaceutical Co.

[0170] In Table 2, "-" indicates that the compound of the column is not used.

[0171] As can be seen from Table 2, the rubber compositions (Examples 1 to 11) containing the high-saturated diene-based polymer and the thermoplastic resin in a prescribed ratio all improved the breaking strength, the wear resistance, and the crack growth resistance in balance, as compared with the rubber compositions (Comparative Examples 1 to 3) not containing the thermoplastic resin.

Claims

1. A rubber composition comprising: (A) a random copolymer having a structural unit derived from a conjugated diene compound and a structural unit derived from an aromatic vinyl compound, wherein, when the molar ratios of the structural unit represented by the following formula (1), the structural unit represented by the following formula (2), the structural unit represented by the following formula (3), and the structural unit represented by the following formula (4) in the polymer are p, q, r, and s, respectively, the value α represented by the following mathematical formula (i) is 0.70 to 0.99, and the polymer has a carbon-carbon unsaturated bond; and (B) thermoplastic resin; The 1,2-vinyl content of the random copolymer is more than 15% by mass and not more than 60% by mass, The resin (B) is a thermoplastic elastomer having a conjugated diene polymer block and a polystyrene block. The polymer (A) is contained in an amount of 60 to 95% by mass relative to the total amount of the polymer (A) and the resin (B), α=(p+(0.5×r)) / (p+q+(0.5×r)+s) …(i) 2. The rubber composition according to claim 1, wherein The polymer (A) has one or more functional groups selected from the group consisting of an amino group, a nitrogen-containing heterocyclic group, a phosphine group, a hydroxyl group, a thiol group, and a hydrocarbyloxysilyl group.

3. The rubber composition according to claim 1 or 2, wherein The polymer (A) has a partial structure derived from at least one selected from the group consisting of a compound represented by the following formula (9), a compound represented by the following formula (10), a compound represented by the following formula (11), and a compound represented by the following formula (12), In formula (9), A 1 It has at least one atom selected from nitrogen, phosphorus, oxygen, sulfur and silicon and is bonded to R via a nitrogen atom, a phosphorus atom, an oxygen atom, a sulfur atom, a silicon atom or a carbon atom contained in a carbonyl group. 5 A monovalent functional group, or a (thio)epoxy group, R 3 and R 4 is a hydrocarbon group, R 5 is an alkylene group, r is an integer from 0 to 2, wherein there are multiple R 3 When multiple R 3 are the same group or different groups, and there are multiple R 4 When multiple R 4 are the same group or different groups, In formula (10), A 2 A compound having at least one atom selected from nitrogen, phosphorus, oxygen, sulfur and silicon, having no active hydrogen and having a nitrogen atom, a phosphorus atom, an oxygen atom, a sulfur atom or a silicon atom bonded to R 9 A monovalent functional group, or a hydrocarbon group having 1 to 20 carbon atoms, R 6 and R 7 are each independently a hydrocarbon group, R 8 is an alkylene group, R 9 is a single bond or an alkylene group, m is 0 or 1, wherein there are multiple R 7 When multiple R 7 are the same group or different groups, In formula (11), A 3 is an imino group, an amide group, a (thio)carbonyl group, a (thio)carbonyloxy group, a thioether group or a polythioether group and L 2 a bonded monovalent group, or a protected primary amino group, a protected secondary amino group, a tertiary amino group, a nitrile group, a pyridyl group, a (thio)epoxy group, a (thio)isocyanate group, a (thio)formyl group, a (thio)carboxylate group, a metal salt of a (thio)carboxylate group, -COX 1 , imidazolyl or a group represented by the following formula (11a), X 1 is a halogen atom, L 2 and L 3 Each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms, R 9 and R 10 Each is independently a hydrocarbon group, k is an integer from 0 to 2, j is 0 or 1, and for R 9 、R 10 and L 3 When there are multiple identical symbols in the formula, the groups represented by the symbols are identical groups or different groups. When there are multiple k in the formula, the multiple k are the same number or different numbers. In formula (11a), L 4 is a single bond or an alkylene group having 1 to 20 carbon atoms, R 11 and R 12 Each is independently a hydrocarbon group, i is an integer from 0 to 3, and "*" represents the same as L 2 Bonding site, for R 11 、R 12 and L 4 The symbols of the group represented by the symbol are the same group or different groups, and the multiple i in the formula are the same number or different numbers, In formula (12), A 4 is an imino group, an amide group, a (thio)carbonyl group or a (thio)carbonyloxy group, Z 1 is a t-valent group having 1 to 20 carbon atoms and containing or not containing a nitrogen atom, L 5 is a single bond or an alkylene group having 1 to 20 carbon atoms, L 6 is an alkylene group having 1 to 20 carbon atoms, R 13 and R 14 Each is independently a hydrocarbon group, h is 0 or 1, t is 2 or 3, and for R 14 、L 5 、L 6 and A 4 The symbols of , the groups represented by the symbols are the same groups or different groups, and the multiple h in the formula are the same number or different numbers.

4. The rubber composition according to claim 1 or 2, wherein It further contains a cross-linking agent. 5 . A cross-linked product obtained by using the rubber composition according to claim 1 .

6. A tire comprising one or both of a tread and a sidewall formed using the crosslinked product according to claim 5.

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