Vulcanized rubber

Abstract

A cross-linked rubber product obtained by cross-linking a rubber composition containing a conjugated diene rubber (A) having an aromatic vinyl monomer unit content of 20% by weight or more, a rubber (B) having an aromatic vinyl monomer unit content of 5% by weight or less, and an inorganic filler (C), wherein the cross-linked rubber product is subjected to a 10 Hz sine wave vibration and the loss tangent is measured using an atomic force microscope, and the cross-linked rubber phase (a) derived from the conjugated diene rubber (A) contains 20% by weight or more of the inorganic filler (C) and The present invention provides a cross-linked rubber product in which the loss tangent value Ka(m) of the non-interface component forming the portion other than the interface of the cross-linked rubber phase (a) and the loss tangent value Ka(i) of the interfacial component forming the interface with the inorganic filler (C) in the cross-linked rubber phase (a), the loss tangent value Kb(m) of the non-interface component forming the portion other than the interface with the inorganic filler (C) in the cross-linked rubber phase (b) derived from the rubber (B), and the loss tangent value Kb(i) of the interfacial component forming the interface with the inorganic filler (C) in the cross-linked rubber phase (b) have a specific relationship.

Description

Technical Field

[0001] The present invention relates to a rubber crosslinked product obtained by crosslinking a rubber composition containing a conjugated diene rubber, a rubber having a content ratio of an aromatic vinyl monomer unit of 5% by weight or less, and an inorganic filler. More specifically, the present invention relates to a rubber crosslinked product excellent in wet grip property, low heat build-up property, and abrasion resistance.

Background Art

[0002] In recent years, due to environmental problems and resource problems, low heat build-up property has been strongly required for automobile tires, and furthermore, excellent wet grip property has been required from the viewpoint of safety. Tires obtained by using a rubber composition in which silica is blended as a filler in a conjugated diene rubber have improved low heat build-up property compared to tires obtained by using a rubber composition blended with conventional carbon black, and thus can be made into tires with lower fuel consumption.

[0003] As a conjugated diene rubber used to provide such a low fuel consumption tire, Patent Document 1 discloses a conjugated diene rubber obtained by reacting a conjugated diene polymer chain having an isoprene block at one end and an active end at the other end with a specific tin halide compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in view of the increasing requirements for automotive tires in recent years, rubber crosslinked products made of conjugated diene rubber newly developed in the future are expected to have even lower heat generation, better wet grip performance, and further wear resistance compared to the rubber crosslinked products made of the conjugated diene rubber described in Patent Document 1 above. The present invention has been made in view of such a situation, and an object thereof is to provide a rubber crosslinked product excellent in wet grip performance, low heat generation, and wear resistance.

Means for Solving the Problems

[0006] As a result of intensive studies on a rubber crosslinked product obtained by crosslinking a rubber composition containing a conjugated diene rubber (A) having an aromatic vinyl monomer unit content ratio of 20% by weight or more, a rubber (B) having an aromatic vinyl monomer unit content ratio of 5% by weight or less, and an inorganic filler (C), when measuring the loss tangent using an atomic force microscope in a state where vibration by a sine wave of 10 Hz is applied, the loss tangent values of non-interface components forming portions other than the interface with the inorganic filler (C) in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B), and the loss tangent value of the interface component forming the interface with the inorganic filler (C) are in a specific relationship, whereby a rubber crosslinked product excellent in wet grip performance, low heat generation, and wear resistance can be obtained, and the present invention has been completed.

[0007] That is, according to the present invention, there is provided a rubber crosslinked product obtained by crosslinking a rubber composition containing a conjugated diene rubber (A) having an aromatic vinyl monomer unit content ratio of 20% by weight or more, a rubber (B) having an aromatic vinyl monomer unit content ratio of 5% by weight or less, and an inorganic filler (C), When measuring the loss tangent using an atomic force microscope while applying vibration by a sine wave of 10 Hz to the rubber crosslinked product, among the crosslinked rubber phase (a) derived from the conjugated diene rubber (A), the loss tangent value Ka(m) of the non-interface component forming a portion other than the interface with the inorganic filler (C), and the ratio Ka(i) / Ka(m) of the loss tangent value Ka(i) of the interface component forming the interface with the inorganic filler (C) among the crosslinked rubber phase (a), When measuring the loss tangent using an atomic force microscope while applying vibration by a sine wave of 10 Hz to the rubber crosslinked product, among the crosslinked rubber phase (b) derived from the rubber (B), the loss tangent value Kb(m) of the non-interface component forming a portion other than the interface with the inorganic filler (C), and the ratio Kb(i) / Kb(m) of the loss tangent value Kb(i) of the interface component forming the interface with the inorganic filler (C) among the crosslinked rubber phase (b), a rubber crosslinked product is provided, characterized in that [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87.

[0008] In the present invention, it is preferable that the glass transition temperature (Tg) of the conjugated diene rubber (A) is -40°C or higher, and the glass transition temperature (Tg) of the rubber (B) is -60°C or lower. In the present invention, it is preferable that the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group. In the present invention, it is preferable that the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group derived from a silicon atom-containing modifier. In the present invention, it is preferable that the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group derived from a siloxane compound or a nitrogen-containing silane compound. In the present invention, it is preferable that the rubber (B) is at least one selected from natural rubber, polybutadiene rubber, and cyclopentene ring-opening polymer rubber. In the present invention, it is preferable that the rubber (B) is a modified rubber having a modifying group. In the present invention, the content ratio of the conjugated diene rubber (A) and the rubber (B) is preferably in a weight ratio of "conjugated diene rubber (A): rubber (B)" of 90:10 to 30:70. In the present invention, the content of the inorganic filler (C) is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the rubber component including the conjugated diene rubber (A) and the rubber (B) in the rubber composition. In the present invention, the inorganic filler (C) is preferably silica.

[0009] Further, according to the present invention, a tire comprising the above rubber crosslinked product is provided.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a rubber crosslinked product excellent in wet grip performance, low heat build-up property and abrasion resistance, and a tire comprising the same.

Modes for Carrying Out the Invention

[0011] The rubber crosslinked product of the present invention is a rubber crosslinked product obtained by crosslinking a rubber composition containing a conjugated diene rubber (A) having a content ratio of an aromatic vinyl monomer unit of 20% by weight or more, a rubber (B) having a content ratio of an aromatic vinyl monomer unit of 5% by weight or less, and an inorganic filler (C), when the loss tangent is measured using an atomic force microscope in a state where vibration by a sine wave of 10 Hz is applied to the rubber crosslinked product, the loss tangent values of the non-interface components forming the portions other than the interface with the inorganic filler (C) in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B), and the loss tangent value of the interface component forming the interface with the inorganic filler (C) are in a specific relationship described below.

[0012] <Rubber Composition> First, the rubber composition used in the present invention will be described. The rubber composition used in the present invention is a rubber composition containing a conjugated diene rubber (A) in which the content ratio of an aromatic vinyl monomer unit is 20% by weight or more, a rubber (B) in which the content ratio of an aromatic vinyl monomer unit is 5% by weight or less, and an inorganic filler (C).

[0013] As the conjugated diene rubber (A) used in the present invention, any polymer may be used as long as it contains a conjugated diene monomer unit as a main structural unit and the content ratio of an aromatic vinyl monomer unit is 20% by weight or more, and it is not particularly limited.

[0014] The conjugated diene compound forming the conjugated diene monomer unit is not particularly limited. For example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene can be mentioned. Among these, 1,3-butadiene, isoprene, and 1,3-pentadiene are preferable, and 1,3-butadiene and isoprene are particularly preferable. These conjugated diene compounds may be used alone or in combination of two or more.

[0015] The aromatic vinyl compound forming the aromatic vinyl monomer unit is not particularly limited. For example, styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylnaphthalene, dimethylaminomethylstyrene, and dimethylaminoethylstyrene can be mentioned. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferable, and styrene is particularly preferable. These aromatic vinyl compounds may be used alone or in combination of two or more.

[0016] As the conjugated diene rubber (A) used in the present invention, those containing an aromatic vinyl monomer unit at a ratio of 20% by weight or more may be used, but those containing an aromatic vinyl monomer unit at a ratio of 20 to 50% by weight are preferred, those containing at a ratio of 20 to 45% by weight are more preferred, those containing at a ratio of 20 to 40% by weight are particularly preferred, and those containing a conjugated diene monomer unit at a ratio of 50 to 80% by weight are preferred, those containing at a ratio of 55 to 80% by weight are more preferred, and those containing at a ratio of 60 to 80% by weight are particularly preferred.

[0017] In addition, as the conjugated diene rubber (A) used in the present invention, in addition to the conjugated diene compound and the aromatic vinyl compound, those obtained by copolymerizing other monomers copolymerizable with the conjugated diene compound and the aromatic vinyl compound may also be used. Examples of other monomers include α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids or acid anhydrides such as acrylic acid, methacrylic acid, and maleic anhydride; unsaturated carboxylic acid esters such as methyl methacrylate, ethyl acrylate, and butyl acrylate; non-conjugated dienes such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene; and the like. These monomers are preferably 10% by weight or less, more preferably 5% by weight or less, as monomer units in the conjugated diene rubber.

[0018] The glass transition temperature (Tg) of the conjugated diene rubber (A) used in the present invention is not particularly limited, but is preferably -40°C or higher, more preferably -35 to -5°C, and even more preferably -30 to -10°C. When the glass transition temperature (Tg) is within the above range, the resulting rubber crosslinked product will have an excellent balance between wet grip performance and low heat build-up performance.

[0019] In the conjugated diene rubber (A) used in the present invention, the vinyl bond content in the conjugated diene monomer unit is not particularly limited, but is preferably 0 to 50 mol%, more preferably 5 to 45 mol%, still more preferably 8 to 40 mol%. When the vinyl bond content is within the above range, the resulting rubber crosslinked product is excellent in the balance between wet grip performance and low heat build-up property.

[0020] The weight average molecular weight (Mw) of the conjugated diene rubber (A) used in the present invention is not particularly limited, but is preferably 50,000 to 2,000,000, more preferably 100,000 to 1,800,000, still more preferably 150,000 to 1,500,000, and particularly preferably 300,000 to 1,200,000. The weight average molecular weight of the conjugated diene rubber can be determined as a polystyrene equivalent value by gel permeation chromatography (hereinafter also referred to as GPC) measurement. When the weight average molecular weight of the conjugated diene rubber is within the above range, the resulting rubber crosslinked product is more excellent in abrasion resistance.

[0021] In addition, the molecular weight distribution represented by the ratio (Mw / Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of the conjugated diene rubber (A) used in the present invention is preferably 1.0 to 1.5, more preferably 1.0 to 1.4, and particularly preferably 1.0 to 1.3. When the value (Mw / Mn) of this molecular weight distribution is within the above range, the resulting rubber crosslinked product is more excellent in low heat build-up property.

[0022] The conjugated diene rubber (A) used in the present invention can be obtained, for example, by polymerizing a monomer mixture containing at least a conjugated diene compound and an aromatic vinyl compound using a polymerization initiator in an inert solvent, and it is preferably polymerized by such a method, that is, a solution polymerization method.

[0023] Examples of the conjugated diene compound and aromatic vinyl compound used as monomers include the same ones as exemplified above as the conjugated diene compound and aromatic vinyl compound that can be used to constitute the conjugated diene rubber (A). Further, as monomers, in addition to the conjugated diene compound and aromatic vinyl compound, other monomers copolymerizable therewith may be used. Examples of the other copolymerizable monomers used as monomers include the same ones as exemplified above as the other copolymerizable monomers that can be used to constitute the conjugated diene rubber (A).

[0024] The inert solvent used for polymerization is one commonly used in solution polymerization and is not particularly limited as long as it does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane, heptane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; aromatic hydrocarbons such as benzene, toluene, and xylene; and the like. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is such that the monomer concentration is, for example, 1 to 50% by weight, preferably 10 to 40% by weight.

[0025] The polymerization initiator used for polymerization is not particularly limited as long as it can polymerize a monomer mixture containing a conjugated diene compound and an aromatic vinyl compound to give a conjugated diene rubber (A). Specific examples thereof include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanide series metal compound, etc. as the main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium; organic polyvalent lithium compounds such as dilithiomethane, 1,4-dithiobutane, 1,4-dithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris(lithiomethyl)benzene; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene; and the like. Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, di-t-butoxystrontium, diethoxy barium, diisopropoxy barium, diethylmercaptopotassium, di-t-butoxy barium, diphenoxy barium, diethylaminobarium, barium distearate, diketyl barium; and the like. Examples of the polymerization initiator using a lanthanide series metal compound as the main catalyst include salts of lanthanide series metals composed of lanthanide series metals such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, carboxylic acids, and phosphorus-containing organic acids as the main catalyst, and polymerization initiators composed of this and cocatalysts such as alkylaluminum compounds, organoaluminum hydride compounds, organoaluminum halide compounds; and the like. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used.Incidentally, the organic alkali metal compound may be reacted in advance with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, and heptamethyleneimine, and used as an organic alkali metal amide compound. These polymerization initiators may be used alone or in combination of two or more.

[0026] The amount of the polymerization initiator used may be determined according to the molecular weight of the target conjugated diene rubber (A), but it is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, more preferably 2 to 15 mmol per 1000 g of the monomer.

[0027] The polymerization temperature is usually in the range of -80 to +150°C, preferably 0 to 100°C, more preferably 30 to 90°C. As the polymerization mode, any mode such as batchwise or continuous can be adopted, but the batchwise mode is preferable in terms of easily controlling the randomness of the bond between the conjugated diene monomer unit and the aromatic vinyl monomer unit.

[0028] In addition, the bonding mode of each monomer unit in the conjugated diene rubber (A) can be various bonding modes such as block, tapered, and random, but a random bonding mode is preferable. By making it random, the low heat build-up property of the resulting rubber crosslinked product can be further enhanced.

[0029] Also, when polymerizing a monomer mixture containing a conjugated diene compound and an aromatic vinyl compound, in order to adjust the vinyl bond content in the conjugated diene monomer units in the resulting conjugated diene rubber (A), it is preferable to add a polar compound to an inert organic solvent. Examples of the polar compound include ether compounds such as dibutyl ether and tetrahydrofuran; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; and the like. Among these, ether compounds and tertiary amines are preferable, tertiary amines are more preferable, and tetramethylethylenediamine is particularly preferable. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound used may be determined according to the target vinyl bond content, and is preferably 0.001 to 100 mol, more preferably 0.01 to 10 mol, per 1 mol of the polymerization initiator. When the amount of the polar compound used is within this range, it is easy to adjust the vinyl bond content in the conjugated diene monomer units, and problems due to deactivation of the polymerization initiator are less likely to occur.

[0030] In the above manner, a conjugated diene rubber (A) can be obtained in an inert solvent. Further, since the conjugated diene rubber (A) thus obtained usually has active terminals, after the polymerization reaction is completed, by adding a polymerization terminator to the polymerization solution, the unreacted active terminals can be deactivated. However, from the viewpoint of making the effects of the present invention more remarkable, it is preferable to further react various modifiers with such active terminals to make the conjugated diene rubber (A) a modified conjugated diene rubber having a modifying group.

[0031] The modifier is not particularly limited, and ordinary modifiers used as modifiers for polymers can be used. However, from the viewpoint that the affinity for inorganic fillers such as silica can be appropriately increased, and the resulting rubber crosslinked product can be made more excellent in wet grip property, low heat generation property, and abrasion resistance, a silicon atom-containing modifier is preferable, and a siloxane compound or a nitrogen-containing silane compound is more preferable.

[0032] As the siloxane compound, any compound having a siloxane structure (-Si-O-) as the main chain structure may be used without particular limitation, but organosiloxane having an organic group in the side chain is preferable, and polyorganosiloxane represented by the following general formula (1) is more preferable.

Chemical formula

[0033] In the above general formula (1), R 1 ~R 8 are each an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same as or different from each other. X 1 and X 4 are each a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a group having 4 to 12 carbon atoms containing an epoxy group, and these may be the same as or different from each other. X 2 is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group. When there are a plurality of X 2 , they may be the same as or different from each other. X 3 is a group containing a repeating unit of alkylene glycol having 2 to 20 carbon atoms. When there are a plurality of X 3 , they may be the same as or different from each other. m is an integer of 0 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m + n + k is 1 or more.

[0034] In the polyorganosiloxane represented by the above general formula (1), R 1 ~R 8 , X 1 and X 4Examples of the alkyl group having 1 to 6 carbon atoms that can constitute the group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, from the viewpoint of the ease of manufacturing the polyorganosiloxane itself, a methyl group and an ethyl group are preferred.

[0035] In the polyorganosiloxane represented by the general formula (1) above, X 1 , X 2 and X 4 Examples of the alkoxy group having 1 to 5 carbon atoms that can constitute the group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, from the viewpoint of the ease of manufacturing the polyorganosiloxane itself, a methoxy group and an ethoxy group are preferred.

[0036] Furthermore, in the polyorganosiloxane represented by the general formula (1) above, X 1 , X 2 and X 4 Examples of the group having 4 to 12 carbon atoms containing an epoxy group that can constitute the group include a group represented by the following general formula (2). -Z 1 -Z 2 -E (2) In the general formula (2) above, Z 1 is an alkylene group having 1 to 10 carbon atoms or an alkylarylene group, Z 2 is a methylene group, a sulfur atom, or an oxygen atom, and E is a hydrocarbon group having 2 to 10 carbon atoms having an epoxy group.

[0037] As the group represented by the general formula (2) above, those in which Z 2 is an oxygen atom are preferred, those in which Z 2 is an oxygen atom and E is a glycidyl group are more preferred, and those in which Z 1 is an alkylene group having 1 to 3 carbon atoms and Z 2It is particularly preferred that is an oxygen atom and E is a glycidyl group.

[0038] In addition, in the polyorganosiloxane represented by the above general formula (1), X 1 and X 4 Among these, a group having 4 to 12 carbon atoms containing an epoxy group or an alkyl group having 1 to 6 carbon atoms is preferable. Further, as X 2 Among these, a group having 4 to 12 carbon atoms containing an epoxy group is preferable. Furthermore, it is more preferable that X 1 and X 4 are alkyl groups having 1 to 6 carbon atoms and X 2 is a group having 4 to 12 carbon atoms containing an epoxy group.

[0039] In addition, in the polyorganosiloxane represented by the above general formula (1), X 3 , that is, as the group containing the repeating unit of 2 to 20 alkylene glycol, a group represented by the following general formula (3) is preferable.

Chemical formula

[0040] In the polyorganosiloxane represented by the above general formula (1), m is an integer of 0 to 200, preferably an integer of 20 to 150, more preferably an integer of 30 to 120. When m is 200 or less, the production of the polyorganosiloxane itself represented by the above general formula (1) becomes easier, its viscosity does not become too high, and handling becomes easier.

[0041] Further, in the polyorganosiloxane represented by the general formula (1), n is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 130. The total number of m, n, and k is 1 or more, preferably 2 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (1) and the active terminal of the conjugated diene rubber easily proceeds. Further, when the total number of m, n, and k is 400 or less, the production of the polyorganosiloxane represented by the general formula (1) itself becomes easy, its viscosity does not become too high, and it is easy to handle.

[0042] Further, the nitrogen-containing silane compound may be any compound containing a nitrogen atom and a silicon atom in one molecule, and is not particularly limited. For example, the compounds listed below can be used.

[0043] That is, first, as a first specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (4) can be mentioned.

Chemical formula

[0044] In the compound represented by the general formula (4), specific examples of the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms are the same as those in the general formula (1).

[0045] In the compound represented by the general formula (4) above, examples of the alkylene group having 1 to 12 carbon atoms include a methylene group, an ethylene group, and a propylene group. Among these, a propylene group is preferable.

[0046] Specific examples of the hydrocarbyloxysilane compound represented by the general formula (4) above include N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane.

[0047] Further, as a second specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (5) is mentioned.

Chemical formula

[0048] In the general formula (5) above, R 20 , R 21 are each independently an organic group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and still more preferably a methyl group, an ethyl group, or a benzyl group. Also, X 7 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group, and X 7The hydrocarbyloxy group that can be a functional group represented by [the formula] is not particularly limited, and examples include alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group; alkenyloxy groups such as vinyloxy group, allyloxy group; aryloxy groups such as phenoxy group, naphthoxy group; aralkyloxy groups such as benzyloxy group; and the like. Among these, an alkoxy group or an aryloxy group is preferred, an alkoxy group is more preferred, and a methoxy group or an ethoxy group is particularly preferred. Also, X 7 The halogen group that can be [the relevant group] is not particularly limited, and examples include fluoro group, chloro group, bromo group, iodo group. Among these, a chloro group is preferred. Also, X 7 may be a hydroxyl group, and this hydroxyl group may be one formed by hydrolysis of a hydrocarbyloxy group or a halogen group that was originally such a group. R 22 is an alkyl group having 1 to 6 carbon atoms, preferably a methyl group or an ethyl group. c is an integer of 0 to 2, d is an integer of 1 to 10, preferably an integer of 1 to 6. X 7 or R 22 When there are a plurality of X 7 or R 22 , the plurality of X 7 or R 22 may be the same as or different from each other.

[0049] Specific examples of the compound represented by the above general formula (5) include 3-(N,N-dimethylamino)propyltriethoxysilane, 3-(N,N-diethylamino)propyltrimethoxysilane, 3-(N,N-diethylamino)propyltriethoxysilane, 3-(N,N-diethylamino)propyltrimethoxysilane, 3-(N,N-dimethylamino)propyldiethoxymethylsilane, 3-(N-benzyl-N-methylamino)propyltrimethoxysilane, 3-(N-phenyl-N-propylamino)pentyltrimethoxysilane, 3-(N,N-dimethylamino)propyltriethoxysilane, 3-(N,N-dimethylamino)propyltrimethoxysilane, 3-(N-allyl-N-methylamino)propyltrimethoxysilane, 3-(N,N-dimethylamino)propyldimethylethoxysilane, 3-(N,N-dimethylamino)propyltriethoxysilane, 3-(N,N-dimethylamino)propyltrimethoxysilane, 3-(N,N-dimethylamino)propyldiisopropylethoxysilane, 3-(N-methyl-N-phenylamino)propyltrimethoxysilane, 3-(N,N-bis[trimethylsilyl]amino)propyltrimethoxysilane, 3-(N,N-diethylamino)propyltrichlorosilane, and the like.

[0050] Further, as a third specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (6) can be mentioned.

Chemical formula

[0051] In the above general formula (6), R 23 is an organic group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms. Further, X 8 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group, and specific examples thereof can be the same as X 7 in the above general formula (5). R 24is an alkyl group having 1 to 6 carbon atoms, preferably a methyl group or an ethyl group. e is an integer of 0 to 1. X 8 When there are a plurality of X 8 may be the same as or different from each other.

[0052] Specific examples of the compound represented by the general formula (6) include 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-dipropoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dipropoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-trimethylsilyl-1-aza-2-silacyclopentane, 2,2-dichloro-1-phenyl-1-aza-2-silacyclopentane, and the like.

[0053] Further, as a fourth specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (7) can be mentioned. [Chemical formula]

[0054] In the general formula (7) above, X 9 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group, R 25 represents a hydrocarbon group which may have a substituent, R 26 , R 27 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, R 26 and R 27 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded. When forming the ring structure, in addition to the nitrogen atom to which they are bonded, a ring structure may be formed together with a hetero atom other than the nitrogen atom to which they are bonded. f is an integer of 1 to 2.

[0055] In the above general formula (7), X 9 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group. Specific examples thereof can be the same as X 7 in the above general formula (5).

[0056] Also, in the above general formula (7), f (that is, the number of functional groups represented by X 9 in formula (7)) is an integer of 1 to 2, preferably 2. When f in the general formula (7) is 2, the two X 9 represented groups contained in one molecule of the compound represented by the general formula (7) may be the same or different from each other.

[0057] In the above general formula (7), R 25 represents a hydrocarbon group which may have a substituent. The hydrocarbon group that R 25 can be is not particularly limited, but includes alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group; alkenyl groups such as vinyl group, allyl group; alkynyl groups such as ethynyl group, propynyl group; aryl groups such as phenyl group, naphthyl group; aralkyl groups such as benzyl group; and the like. Among these, an alkyl group or an aryl group is preferable, and an alkyl group is more preferable. Further, the hydrocarbon group represented by R 25 may have a substituent other than the hydrocarbon group. The substituent is not particularly limited, and examples thereof include carbonyl group-containing groups such as carboxyl group, acid anhydride group, hydrocarbylcarbonyl group, alkoxycarbonyl group, acyloxy group, and epoxy group, oxy group, cyano group, amino group, halogen group, and the like.

[0058] In the above general formula (7), R 26 and R 27 are each independently a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and R 26 and R 27may be bonded to each other to form a ring structure together with the nitrogen atom represented by "N" in the general formula (7). R 26 and R 27 When not bonded to each other, the hydrocarbon group that R 26 and R 27 may be is not particularly limited, but examples include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group; alkenyl groups such as vinyl group, allyl group; alkynyl groups such as ethynyl group, propynyl group; aryl groups such as phenyl group, naphthyl group; aralkyl groups such as benzyl group; and the like. Among these, an alkyl group or an aryl group is preferable, an alkyl group is more preferable, and a methyl group or an ethyl group is particularly preferable. Also, when R 26 and R 27 are bonded to each other to form a ring structure, the divalent hydrocarbon group formed by the bonding of R 26 and R 27 is not particularly limited, but examples include n-butylene group (when forming a 1-pyrrolidine group together with the nitrogen atom represented by "N" in the general formula (7)), n-pentylene group (when forming a 1-piperidine group), butadienylene group (when forming a 1-pyrrole group), and the like.

[0059] Also, the hydrocarbon group represented by R 26 and R 27 may have a substituent other than a hydrocarbon group regardless of whether a ring structure is formed or not. The substituent is not particularly limited, and examples include carbonyl group-containing groups such as carboxyl group, acid anhydride group, hydrocarbylcarbonyl group, alkoxycarbonyl group, acyloxy group, and epoxy group, oxy group, cyano group, amino group, halogen group, and the like. Further, R 26 and R 27When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the atoms forming the ring structure may include carbon atoms and heteroatoms other than the nitrogen atom represented by "N" in the general formula (7), and examples of such heteroatoms include nitrogen atoms and oxygen atoms.

[0060] In the present invention, among the compounds represented by the above general formula (7), particularly preferred are those in which the hydrocarbon groups represented by R 26 and R 27 are bonded to each other to form a piperazine ring structure together with the nitrogen atom represented by "N" in the general formula (7). More specifically, it is preferable to use a compound represented by the following general formula (8).

Chemical formula

[0061] In the above general formula (8), X 9 , R 25 , and f all represent the same as those in the above general formula (7), and R 28 represents a hydrocarbon group having 1 to 20 carbon atoms.

[0062] In the above general formula (8), R 28 represents a hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group that can be R 28 is not particularly limited, but examples include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group; alkenyl groups such as vinyl group, allyl group; alkynyl groups such as ethynyl group, propynyl group; aryl groups such as phenyl group, naphthyl group; aralkyl groups such as benzyl group; and the like. Among these, an alkyl group or an aryl group is preferable, an alkyl group is more preferable, and a methyl group is particularly preferable.

[0063] Specific examples of the compound represented by the general formula (7) include 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-diethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane, 2-methoxy-2-methyl-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dichloro-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, and the like.

[0064] Further, as a fifth specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (9) can be mentioned.

Chemical formula

[0065] In the above general formula (9), X 10 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group, and specific examples thereof can be the same as X 7 in the above general formula (5). R 29 is an alkyl group having 1 to 6 carbon atoms, preferably a methyl group or an ethyl group. Also, R 30 , R 31 , R 32 are each independently an organic group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group. g is an integer of 0 to 2, h is an integer of 1 to 10, and j is an integer of 1 to 10. When there are a plurality of X 10 or R 29 , the plurality of X 10 or R 29 may be the same as or different from each other.

[0066] Specific examples of the compound represented by the above general formula (9) include 3-[N-2-{N’,N’-bis(trimethylsilyl)amino}ethyl-N-trimethylsilylamino]propyltriethoxysilane, 3-[N-2-{N’,N’-bis(triethylsilyl)amino}ethyl-N-triethylsilylamino]propyltriethoxysilane, 3-[N-2-{N’,N’-bis(triethylsilyl)amino}ethyl-N-triethylsilylamino]propyltrichlorosilane, and the like.

[0067] Furthermore, as a sixth specific example of the nitrogen-containing silane compound, a compound represented by the following general formula (10) can be mentioned.

Chemical formula

[0068] In the above general formula (10), X 11 represents a functional group selected from a hydrocarbyloxy group, a halogen group, and a hydroxyl group, and specific examples thereof can be the same as X 7 in the above general formula (5). R 33 is an alkyl group having 1 to 6 carbon atoms, preferably a methyl group or an ethyl group. Also, R 34 , R 35 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms. p is an integer of 0 to 2, and q is an integer of 1 to 10. When there are a plurality of X 11 or R 33 , the plurality of X 11 or R 33 may be the same as or different from each other.

[0069] Specific examples of the compound represented by the general formula (10) include N-(3-triethoxysilylpropyl)-4-methylpentan-2-imine, N-(3-trimethoxysilylpropyl)-4-methylpentan-2-imine, N-(3-triethoxysilylpropyl)propan-2-imine, N-(3-triethoxysilylpropyl)pentan-3-imine, N-(3-trichlorosilylpropyl)-4-methylpentan-2-imine, and the like.

[0070] Among the above nitrogen-containing silane compounds, the compounds represented by the general formula (5), the general formula (7), or the general formula (9) are preferred, the compounds represented by the general formula (5) or the general formula (7) are more preferred, and the compound represented by the general formula (7) is particularly preferred.

[0071] When reacting the above-mentioned modifier with the active terminal of the conjugated diene rubber, the amount of the modifier used is not particularly limited, but the amount of the modifier relative to 1 mol of the active terminal of the conjugated diene rubber having an active terminal (when an organic alkali metal compound is used as the polymerization initiator, the amount of the modifier relative to 1 mol of the metal atom in the organic alkali metal compound) is preferably 0.01 to 10.0 mol, more preferably 0.02 to 5.0 mol, and particularly preferably 0.05 to 2.0 mol. The modifiers may be used alone or in combination of two or more.

[0072] Further, as a method for reacting a modifier with the active terminal of the conjugated diene rubber, it is not particularly limited, and examples thereof include a method of mixing a conjugated diene rubber having an active terminal and a modifier in a solvent capable of dissolving them. As the solvent used in this case, those exemplified as the solvent used for the polymerization of the above-described conjugated diene rubber (A) can be used. Further, in this case, it is convenient and preferable to use the conjugated diene rubber having an active terminal obtained above as it is in the state of the polymerization solution used for its polymerization and add a modifier thereto. In this case, the modifier may be dissolved in the above-described inert solvent used for the polymerization and added to the polymerization system, and the solution concentration is preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

[0073] The timing of adding the modifier to the solution containing the conjugated diene rubber having an active terminal is not particularly limited, but the polymerization reaction is not completed, and the solution containing the conjugated diene rubber having an active terminal also contains a monomer. More specifically, it is desirable to add the modifier to this solution in a state where the solution containing the conjugated diene rubber having an active terminal contains 100 ppm or more, more preferably 300 to 50,000 ppm of the monomer. By adding the modifier in this way, it is possible to suppress side reactions between the conjugated diene rubber having an active terminal and impurities contained in the polymerization system, and to control the reaction well.

[0074] In addition, before reacting the modifier with the conjugated diene rubber having an active terminal, a part of the active terminal of the conjugated diene rubber may be inactivated by adding a conventionally commonly used coupling agent or the like to the polymerization system within a range that does not inhibit the effects of the present invention.

[0075] After reacting the modifier with the conjugated diene rubber having an active terminal, if unreacted active terminals remain, it is preferable to add a polymerization terminator such as an alcohol such as methanol, ethanol, isopropanol or water to the polymerization solution to deactivate the unreacted active terminals.

[0076] In the solution of the conjugated diene rubber (A) obtained as described above (including the case where it is a modified conjugated diene rubber; the same shall apply hereinafter), antioxidants such as phenolic stabilizers, phosphorus stabilizers, and sulfur stabilizers may be added if desired. The addition amount of the antioxidant may be appropriately determined according to its type and the like. Further, if desired, an extender oil may be blended to obtain an oil-extended rubber. Examples of the extender oil include paraffinic, aromatic, and naphthenic petroleum softeners, vegetable softeners, and fatty acids. When using a petroleum softener, it is preferable that the content of polycyclic aromatics extracted by the method of IP346 (the test method of THE INSTITUTE PETROLEUM in the UK) is less than 3%. When using an extender oil, the amount used is usually 5 to 100 parts by weight based on 100 parts by weight of the conjugated diene rubber.

[0077] And the conjugated diene rubber (A) thus obtained can be obtained as a solid conjugated diene rubber (A) by separating it from the reaction mixture, for example, by removing the solvent by steam stripping.

[0078] The rubber composition used in the present invention contains, in addition to the conjugated diene rubber (A) described above, a rubber (B) having a content ratio of aromatic vinyl monomer units of 5% by weight or less.

[0079] As the rubber (B), those having a glass transition temperature (Tg) of -40°C or lower are preferred, those having a glass transition temperature (Tg) of -50 to -120°C are more preferred, and those having a glass transition temperature (Tg) of -55 to -120°C are even more preferred, from the viewpoint that the abrasion resistance of the resulting rubber crosslinked product can be further enhanced. Further, as the rubber (B), those incompatible with the conjugated diene rubber (A) described above are preferred. By using, as the rubber (B), those incompatible with the conjugated diene rubber (A), the resulting rubber crosslinked product can be made into a product in which the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B) are preferably phase-separated, and thereby, it becomes possible to further enhance the abrasion resistance of the resulting rubber crosslinked product. In addition, the fact that the conjugated diene rubber (A) and the rubber (B) are incompatible with each other means that, when a mixture obtained by mixing these with each other is observed with an electron microscope or the like, it is sufficient that a phase separation structure can be confirmed, and it is not particularly limited.

[0080] As the rubber (B), a rubber having a content ratio of an aromatic vinyl monomer unit of 5% by weight or less may be used, and it is not particularly limited. Specific examples thereof include natural rubber, polyisoprene rubber, polybutadiene rubber (which may be high cis-BR or low cis BR. Further, it may be a polybutadiene rubber containing crystalline fibers composed of a 1,2-polybutadiene polymer.), butadiene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, and acrylonitrile-styrene-butadiene copolymer rubber, etc., conjugated diene rubbers having a content ratio of an aromatic vinyl monomer unit of 5% by weight or less, and cyclopentene ring-opening polymer rubber, etc. These may be modified rubbers having a modifying group or unmodified rubbers, and each may be used alone or in combination of two or more. Among these, natural rubber, polybutadiene rubber, and cyclopentene ring-opening polymer rubber are preferred from the viewpoint that the abrasion resistance of the resulting rubber crosslinked product can be further enhanced, and from the viewpoint that the wet grip property, low heat generation property, and abrasion resistance of the resulting rubber crosslinked product can be further improved, it is more preferred that these have a modifying group.

[0081] For example, as the polybutadiene rubber having a modifying group, those obtained by the following methods can be mentioned. That is, in an inert solvent, using a polymerization initiator having an organic alkali metal compound, an organic alkaline earth metal compound, or a lanthanide series metal compound as a main catalyst, a monomer containing 1,3-butadiene is polymerized, and the obtained polymer chain having an active terminal is reacted with the above-mentioned silicon atom-containing modifier (for example, the modifier represented by the above general formulas (1) to (10)), etc. can be used.

[0082] In addition, as the cyclopentene ring-opening polymer rubber having a modifying group, those obtained by the following methods can be mentioned. That is, in an inert solvent, a polymerization catalyst containing a Group 6 transition metal compound of the periodic table and a compound of the formula: (R 35 ) 3-x Al(OR 36 ) x (wherein R 35 and R 36 represent a hydrocarbon group having 1 to 20 carbon atoms, and x is 0 < x < 3.), and in the presence of a modifying group-containing olefinically unsaturated hydrocarbon such as an oxy-silyl group-containing olefinically unsaturated hydrocarbon, a monomer containing cyclopentene is polymerized, and the like can be used.

[0083] Examples of such olefinically unsaturated hydrocarbons containing an oxysilyl group include, as those in which a modifying group is introduced only at one end (one terminal) of the polymer chain of a cyclopentene ring-opening polymer, alkoxysilane compounds such as vinyl(trimethoxy)silane, vinyl(triethoxy)silane, allyl(trimethoxy)silane, allyl(methoxy)(dimethyl)silane, allyl(triethoxy)silane, allyl(ethoxy)(dimethyl)silane, styryl(trimethoxy)silane, styryl(triethoxy)silane, 2-styrylethyl(triethoxy)silane, allyl(triethoxysilylmethyl)ether, allyl(triethoxysilylmethyl)(ethyl)amine; aryloxysilane compounds such as vinyl(triphenoxy)silane, allyl(triphenoxy)silane, allyl(phenoxy)(dimethyl)silane; acyloxysilane compounds such as vinyl(triacetoxy)silane, allyl(triacetoxy)silane, allyl(diacetoxy)methylsilane, allyl(acetoxy)(dimethyl)silane; alkylsiloxysilane compounds such as allyltris(trimethylsiloxy)silane; arylsiloxysilane compounds such as allyltris(triphenylsiloxy)silane; polysiloxane compounds such as 1-allylheptamethyltrisiloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, 1-allylundecamethylcyclohexasiloxane; and the like.In addition, as a method of introducing a modifying group to both ends (both terminals) of the polymer chain of the cyclopentene ring-opening polymer, alkoxysilane compounds such as 1,4-bis(trimethoxysilyl)-2-butene, 1,4-bis(triethoxysilyl)-2-butene, 1,4-bis(trimethoxysilylmethoxy)-2-butene; aryloxysilane compounds such as 1,4-bis(triphenoxysilyl)-2-butene; acyloxysilane compounds such as 1,4-bis(triacetoxysilyl)-2-butene; alkylsiloxysilane compounds such as 1,4-bis[tris(trimethylsiloxy)silyl]-2-butene; arylsiloxysilane compounds such as 1,4-bis[tris(triphenylsiloxy)silyl]-2-butene; polysiloxane compounds such as 1,4-bis(heptamethyltrisiloxy)-2-butene, 1,4-bis(undecamethylcyclohexasiloxy)-2-butene; and the like can be mentioned.

[0084] In the rubber composition used in the present invention, the content ratio of the conjugated diene rubber (A) and the rubber (B) is preferably 90:10 to 30:70, more preferably 80:20 to 40:60, and still more preferably 70:30 to 50:50 in terms of the weight ratio of "conjugated diene rubber (A):rubber (B)". By setting the content ratio of the conjugated diene rubber (A) and the rubber (B) within the above range, the abrasion resistance of the obtained rubber crosslinked product can be more appropriately enhanced.

[0085] In addition, the rubber composition used in the present invention contains an inorganic filler (C) in addition to the conjugated diene rubber (A) and the rubber (B) described above.

[0086] The inorganic filler (C) is not particularly limited, but at least one inorganic filler selected from silica and carbon black is preferable, and silica is more preferable in that the obtained rubber crosslinked product can be made excellent in low heat generation property.

[0087] Examples of the silica include dry-process white carbon, wet-process white carbon, colloidal silica, precipitated silica, etc. Among these, wet-process white carbon mainly composed of hydrous silicic acid is preferable. Alternatively, a carbon-silica dual-phase filler in which silica is supported on the surface of carbon black may be used. These silicas can be used alone or in combination of two or more. The nitrogen adsorption specific surface area of the silica used (measured by the BET method in accordance with ASTM D3037-81) is preferably 50 to 300 m 2 / g, more preferably 80 to 220 m 2 / g, particularly preferably 100 to 170 m 2 / g. Also, the pH of the silica is preferably 5 to 10.

[0088] Examples of the carbon black include furnace black, acetylene black, thermal black, channel black, graphite, etc. When using carbon black, it is preferable to use furnace black, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS, T-HS, T-NS, MAF, FEF, etc. These carbon blacks can be used alone or in combination of two or more.

[0089] The compounding amount of the inorganic filler (C) in the rubber composition used in the present invention is preferably 10 to 200 parts by weight, more preferably 30 to 150 parts by weight, and still more preferably 40 to 100 parts by weight with respect to 100 parts by weight of the rubber component containing the conjugated diene rubber (A) and the rubber (B) in the rubber composition. By setting the compounding amount of the inorganic filler (C) within the above range, the processability of the rubber composition becomes excellent, and the obtained rubber crosslinked product can be made excellent in wet grip property and low heat build-up property.

[0090] In the rubber composition used in the present invention, when silica is used as the inorganic filler (C), a silane coupling agent may be further compounded from the viewpoint of further improving the low heat build-up property. Examples of the silane coupling agent include vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-octanoylthio-1-propyl-triethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide, and γ-trimethoxysilylpropylbenzothiazyltetrasulfide. These silane coupling agents can be used alone or in combination of two or more. The compounding amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, based on 100 parts by weight of silica.

[0091] Further, the rubber composition used in the present invention preferably further contains a crosslinking agent. Examples of the crosslinking agent include sulfur-containing compounds such as sulfur and sulfur halides, organic peroxides, quinone dioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Among these, sulfur is preferably used. The compounding amount of the crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component containing the conjugated diene rubber (A) and the rubber (B) in the rubber composition.

[0092] Furthermore, in addition to the above components, compounding agents such as a crosslinking accelerator, a crosslinking activator, an antioxidant, an organic filler, an activator, a process oil, a plasticizer, a lubricant, and a tackifier can be compounded in necessary amounts according to conventional methods in the rubber composition used in the present invention.

[0093] When sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator in combination. Examples of the crosslinking accelerator include sulfenamide-based crosslinking accelerators; guanidine-based crosslinking accelerators; thiourea-based crosslinking accelerators; thiazole-based crosslinking accelerators; thiuram-based crosslinking accelerators; dithiocarbamic acid-based crosslinking accelerators; xanthogenic acid-based crosslinking accelerators; and the like. Among these, those containing sulfenamide-based crosslinking accelerators are preferable. These crosslinking accelerators can be used alone or in combination of two or more. The compounding amount of the crosslinking accelerator is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight with respect to 100 parts by weight of the rubber component containing the conjugated diene rubber (A) and the rubber (B) in the rubber composition.

[0094] Examples of the crosslinking activator include higher fatty acids such as stearic acid; zinc oxide; and the like. These crosslinking activators can be used alone or in combination of two or more. The compounding amount of the crosslinking activator is preferably 0.05 to 20 parts by weight, and particularly preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the rubber component containing the conjugated diene rubber (A) and the rubber (B) in the rubber composition.

[0095] As a method for obtaining the rubber composition used in the present invention, a method of kneading each component according to a conventional method may be adopted. For example, after kneading a compounding agent such as an inorganic filler (C) and a rubber component containing the above-mentioned conjugated diene rubber (A) and rubber (B), excluding heat-labile components such as a crosslinking agent and a crosslinking accelerator, a heat-labile component such as a crosslinking agent and a crosslinking accelerator is mixed with the kneaded product to obtain the target composition. The kneading temperature of the compounding agent excluding the heat-labile component and the rubber component is preferably 80 to 200°C, more preferably 120 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. Further, the mixing of the kneaded product and the heat-labile component is usually carried out after cooling to 100°C or lower, preferably 80°C or lower.

[0096] <Rubber crosslinked product> The rubber crosslinked product of the present invention is obtained by crosslinking a rubber composition containing the conjugated diene rubber (A), the rubber (B), and the inorganic filler described above. When measuring the loss tangent using an atomic force microscope in a state where vibration by a sine wave of 10 Hz is applied to the rubber crosslinked product, among the crosslinked rubber phase (a) derived from the conjugated diene rubber (A), the loss tangent value Ka(m) of the non-interface component forming a portion other than the interface with the inorganic filler (C), and the loss tangent value Ka(i) of the interface component forming the interface with the inorganic filler (C) among the crosslinked rubber phase (a), the ratio Ka(i) / Ka(m) of them, When measuring the loss tangent using an atomic force microscope in a state where vibration by a sine wave of 10 Hz is applied to the rubber crosslinked product, among the crosslinked rubber phase (b) derived from the rubber (B), the loss tangent value Kb(m) of the non-interface component forming a portion other than the interface with the inorganic filler (C), and the loss tangent value Kb(i) of the interface component forming the interface with the inorganic filler (C) among the crosslinked rubber phase (b), the ratio Kb(i) / Kb(m) of them are controlled such that [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87.

[0097] According to the present invention, the rubber crosslinked product is obtained by crosslinking a rubber composition containing a conjugated diene rubber (A), a rubber (B), and an inorganic filler. When a vibration caused by a sine wave of 10 Hz is applied, the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B) satisfy the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87. By controlling in this way, the rubber crosslinked product can be made excellent in wet grip performance, low heat build-up property, and abrasion resistance. In particular, the inventors of the present invention focused on the interfacial state between the crosslinked rubber and the inorganic filler in the rubber crosslinked product in order to improve the wet grip performance, low heat build-up property, and abrasion resistance, and conducted intensive studies. As a result, the following findings were obtained. That is, the rubber crosslinked product is substantially composed of a crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and a crosslinked rubber phase (b) derived from the rubber (B) (that is, it has mutually incompatible crosslinked rubber phases (a) and (b) that are phase-separated). When a vibration caused by a sine wave of 10 Hz is applied, the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B) satisfy the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87. By controlling in this way, it has been found that the wet grip performance, low heat build-up property, and abrasion resistance of the rubber crosslinked product when a vibration caused by a sine wave of 10 Hz is applied can be improved.

[0098] Here, the loss tangent value Ka(m) is the loss tangent value of the non-interface component that forms the part other than the interface with the inorganic filler (C) among the crosslinked rubber phase (a) derived from the conjugated diene rubber (A), and the loss tangent value Ka(i) is the loss tangent value of the interface component that forms the interface with the inorganic filler (C) among the crosslinked rubber phase (a) derived from the conjugated diene rubber (A). Further, the loss tangent value Kb(m) is the loss tangent value of the non-interface component that forms the part other than the interface with the inorganic filler (C) among the crosslinked rubber phase (b) derived from the rubber (B), and the loss tangent value Kb(i) is the loss tangent value of the interface component that forms the interface with the inorganic filler (C) among the crosslinked rubber phase (b) derived from the rubber (B).

[0099] Note that the loss tangent value Ka(m) of the non-interface component in the crosslinked rubber phase (a) is the loss tangent value of the crosslinked rubber part that is not substantially affected by the inorganic filler (C) among the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) that constitutes the rubber crosslinked product (the part of the crosslinked rubber component derived from the conjugated diene rubber (A) that is sufficiently separated from the inorganic filler (C)), that is, the non-interface forming crosslinked rubber part. The larger this loss tangent value Ka(m), the easier it is to move following a sine wave at a relatively low frequency of 10 Hz when a vibration by a sine wave of 10 Hz is applied. Similarly, the loss tangent value Kb(m) of the non-interface component in the crosslinked rubber phase (b) is the loss tangent value of the crosslinked rubber part that is not substantially affected by the inorganic filler (C) among the crosslinked rubber phase (b) derived from the rubber (B) that constitutes the rubber crosslinked product (the part of the crosslinked rubber component derived from the rubber (B) that is sufficiently separated from the inorganic filler (C)), that is, the non-interface forming crosslinked rubber component part. The larger this loss tangent value Kb(m), the easier it is to move following a sine wave at a relatively low frequency of 10 Hz when a vibration by a sine wave of 10 Hz is applied.

[0100] Further, the loss tangent value Ka(i) of the interfacial component in the crosslinked rubber phase (a) is the loss tangent value in the crosslinked rubber portion that forms the interface with the inorganic filler (C) among the crosslinked rubber phases (a) derived from the conjugated diene rubber (A) constituting the rubber crosslinked product, that is, the crosslinked rubber portion forming the interface. The smaller this loss tangent value Ka(i), the more difficult it is to move when a vibration by a sine wave of 10 Hz is applied. Therefore, it can be determined that it strongly interacts with the inorganic filler (C). Similarly, the loss tangent value Kb(i) of the interfacial component in the crosslinked rubber phase (b) is the loss tangent value in the crosslinked rubber portion that forms the interface with the inorganic filler (C) among the crosslinked rubber phases (b) derived from the rubber (B) constituting the rubber crosslinked product, that is, the crosslinked rubber portion forming the interface. The smaller this loss tangent value Kb(i), the more difficult it is to move when a vibration by a sine wave of 10 Hz is applied. Therefore, it can be determined that it strongly interacts with the inorganic filler (C).

[0101] And in the present invention, the product [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)], which is the ratio of the loss tangent value Ka(i) of the interfacial component and the loss tangent value Ka(m) of the non-interfacial component in the crosslinked rubber phase (a), and the ratio of the loss tangent value Kb(i) of the interfacial component and the loss tangent value Kb(m) of the non-interfacial component in the crosslinked rubber phase (b) when a vibration by a sine wave of 10 Hz is applied, is controlled to be 0.87 or less. Thereby, the wet grip property, low heat generation property, and abrasion resistance of the rubber crosslinked product can be improved. Note that [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)] is preferably 0.80 or less, more preferably 0.70 or less, and even more preferably 0.65 or less. Also, the lower limit thereof is not particularly limited, but is usually 0.1 or more. Further, Ka(i) / Ka(m) is not particularly limited, but is preferably 0.90 or less, more preferably 0.85 or less, and even more preferably 0.75 or less, and Kb(i) / Kb(m) is also not particularly limited, but is preferably 0.95 or less, more preferably 0.90 or less, and even more preferably 0.85 or less. The lower limits of these are not particularly limited, but are usually 0.1 or more.

[0102] As a method for measuring the loss tangent values Ka(m) and Kb(m) of the non-interface component and the loss tangent values Ka(i) and Kb(i) of the interface component when vibration is applied by a 10 Hz sine wave, there is no particular limitation. For a rubber crosslinked product, while applying vibration by a 10 Hz sine wave (preferably with an amplitude of 1 to 10 nm), at room temperature (25°C), preferably with a resolution of 0.1 to 300 nm, more preferably with a resolution of 0.1 to 100 nm, any method capable of measuring the loss tangent (loss tangent = loss elastic modulus / storage elastic modulus) may be used, but usually, an atomic force microscope is used. The atomic force microscope is not particularly limited, and an atomic force microscope manufactured by Bruker, an atomic force microscope manufactured by OXFORD INSTRUMENTS, etc. can be used without limitation. Further, in the present invention, the loss tangent is measured using an atomic force microscope, but any method capable of measuring with the above-described resolution while applying vibration by a 10 Hz sine wave can be used without particular limitation, even if it is a method other than using an atomic force microscope. Further, in the present invention, the loss tangent is measured by applying vibration by a 10 Hz sine wave, but it is also possible to change the frequency of the sine wave by changing the measurement temperature (for example, by setting a temperature other than 25°C). Specifically, it is also possible to perform the measurement by changing the measurement temperature and the frequency of the sine wave so as to be the same conditions as when vibration is applied by a 10 Hz sine wave at 25°C.

[0103] As a specific method for measuring the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components when applying vibration with a 10 Hz sine wave, for example, it can be measured according to the methods described in "Nanorheological Mapping of Rubbers by Atomic Force microscopy", macromolecules, 46, 1916-1922(2013) and "Viscoelasticity of Inhomogeneous Polymers Characterized by Loss Tangent Measurements Using Atomic Force Microscopy, macromolecules, 47, 7971-7977(2014).

[0104] For example, first, a test piece is obtained by slicing a rubber crosslinked product in the thickness direction. For a 1 μm × 1 μm range of the cross-section of the obtained test piece, using an atomic force microscope, at 25 °C, force volume measurement is performed with a resolution of 64 × 64 (a resolution of 15.6 nm) to obtain the elastic modulus X at each measurement site. Then, for the elastic modulus X at each obtained measurement site, a histogram with the elastic modulus X on the horizontal axis and the frequency on the vertical axis is created, and the histogram is analyzed by a Gaussian function to identify the peak on the low elastic modulus side and the peak on the high elastic modulus side. Then, for each of the identified peak on the low elastic modulus side and the peak on the high elastic modulus side, it is specified which peak corresponds to the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B). Note that which rubber phase each of these peaks corresponds to can be specified from the elastic modulus originally possessed by the rubber phase and the blending ratio of the conjugated diene rubber (A) and the rubber (B).

[0105] Then, based on the elastic modulus peak identified as corresponding to the crosslinked rubber phase (a) derived from the conjugated diene rubber (A), the average value Xm_a and the standard deviation σ_a of the elastic modulus based on the elastic modulus peak are calculated. A measurement site where Xm_a - 2σ_a ≤ X ≤ Xm_a + 2σ_a is specified as the crosslinked rubber portion that is not substantially affected by the inorganic filler (C) among the crosslinked rubber phases (a) derived from the conjugated diene rubber (A) (a portion of the crosslinked rubber components constituting the crosslinked rubber phase (a) that is sufficiently separated from the inorganic filler (C)), that is, as the non-interface-forming crosslinked rubber portion. On the other hand, a measurement site where Xm_a + 3σ_a ≤ X ≤ Xm_a + 9σ_a is specified as the portion of the crosslinked rubber components constituting the rubber crosslinked product that forms an interface with the inorganic filler (C), that is, as the interface-forming crosslinked rubber component portion.

[0106] Similarly, based on the elastic modulus peak identified as corresponding to the crosslinked rubber phase (b) derived from the rubber (B), the average value Xm_b and the standard deviation σ_b of the elastic modulus based on the elastic modulus peak are calculated. A measurement site where Xm_b - 2σ_b ≤ X ≤ Xm_b + 2σ_b is specified as the crosslinked rubber portion that is not substantially affected by the inorganic filler (C) among the crosslinked rubber phases (b) derived from the conjugated diene rubber (B) (a portion of the crosslinked rubber components constituting the crosslinked rubber phase (b) that is sufficiently separated from the inorganic filler (C)), that is, as the non-interface-forming crosslinked rubber portion. On the other hand, a measurement site where Xm_b + 3σ_b ≤ X ≤ Xm_b + 9σ_b is specified as the portion of the crosslinked rubber components constituting the rubber crosslinked product that forms an interface with the inorganic filler (C), that is, as the interface-forming crosslinked rubber component portion.

[0107] Next, for the test pieces identified for each measurement site by the above method, while applying vibration with a 10 Hz sine wave at an amplitude of 5 nm, for the same range, using an atomic force microscope, at 25 °C, at a resolution of 64×64 (a resolution of 15.6 nm), by performing force volume measurement, the amount of deformation and phase delay of the test piece are measured, and the loss tangent value K at each measurement site is measured. Then, for the loss tangent value K at each measurement site, for each of the non-interface-forming crosslinked rubber component part and the interface-forming crosslinked rubber component part of the crosslinked rubber phase (a) identified above, and for each of the non-interface-forming crosslinked rubber component part and the interface-forming crosslinked rubber component part of the crosslinked rubber phase (b), by calculating the average value, the loss tangent value of the non-interface-forming crosslinked rubber component part, that is, the loss tangent values Ka(m), Kb(m) of the non-interface components forming the part other than the interface with the inorganic filler (C), and the loss tangent value of the interface-forming crosslinked rubber component part, that is, the loss tangent values Ka(i), Kb(i) of the interface components forming the interface with the inorganic filler (C) can be calculated, and the ratios Ka(i) / Ka(m), Kb(i) / Kb(m) of these are calculated, and using these, [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)] can be obtained. Note that the identification for each measurement site and the measurement of the loss tangent values Ka(m), Kb(m), Ka(i), Kb(i) may be performed separately or simultaneously.

[0108] In addition, in the measurement using the atomic force microscope described above, since the measurable resolution changes depending on the size of the probe used for the measurement, in order to enable the measurement at the above resolution, as the probe, it is preferable to use a probe having a tip curvature radius of 1 to 100 nm (for example, a cantilever having such a tip curvature radius), and it is more preferable to use a probe having a tip curvature radius of 1 to 30 nm. Further, as the cantilever, it is preferable to use a cantilever having a spring constant of 0.05 to 100 N / m, more preferably 0.2 to 40 N / m, and even more preferably 0.5 to 5 N / m. Further, as the cantilever, it is preferable to use a cantilever having a resonance frequency of 1 to 2000 kHz, more preferably 10 to 500 kHz, and even more preferably 40 to 100 kHz.

[0109] In the present invention, as a method for satisfying the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87 for the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B) when a vibration by a sine wave of 10 Hz is applied, although not particularly limited, the types of the conjugated diene rubber (A) and the rubber (B) used, the molecular weights of the conjugated diene rubber (A) and the rubber (B), the content ratio of the aromatic vinyl unit in the conjugated diene rubber (A), the vinyl bond content in the conjugated diene monomer unit in the conjugated diene rubber (A), the presence or absence of the introduction of the modified group in the conjugated diene rubber (A) and the rubber (B), the type and the introduction rate of the modified group to be introduced, the method for adjusting the compounding amount and the particle diameter of the inorganic filler (C) used when preparing the rubber composition, and further, the method for adjusting the kneading conditions when preparing the rubber composition, etc. are mentioned, and it is desirable to appropriately combine these.

[0110] The method for producing the rubber crosslinked product of the present invention is not particularly limited. However, using the above-described rubber composition, for example, molding is performed by a molding machine corresponding to a desired shape, such as an extruder, an injection molding machine, a compressor, a roll, etc., and a crosslinking reaction is carried out by heating, and it can be produced by fixing the shape as a crosslinked product. In this case, crosslinking may be performed after pre-molding or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The crosslinking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, particularly preferably 3 minutes to 6 hours.

[0111] In addition, depending on the shape, size, etc. of the rubber crosslinked product, there may be a case where even though the surface is crosslinked, the inside is not sufficiently crosslinked. Therefore, secondary crosslinking may be performed by further heating.

[0112] As the heating method, a general method used for crosslinking rubber, such as press heating, steam heating, oven heating, hot air heating, etc., may be appropriately selected.

[0113] The rubber crosslinked product of the present invention is such that when subjected to vibration by a sine wave of 10 Hz, the loss tangent values Ka(m) and Kb(m) of the non-interface components and the loss tangent values Ka(i) and Kb(i) of the interface components in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B) are controlled to satisfy the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87. As a result, it is excellent in wet grip performance, low heat generation property, and abrasion resistance. And the rubber crosslinked product of the present invention makes use of such characteristics. For example, in a tire, it can be used as a material for each part of the tire such as a cap tread, a base tread, a carcass, a sidewall, and a bead part; a material for hoses, belts, mats, vibration-proof rubbers, and other various industrial supplies; an impact resistance improver for resins; a resin film buffer; a shoe sole; a rubber shoe; a golf ball; a toy; etc. for various applications. In particular, since the rubber crosslinked product of the present invention is excellent in wet grip performance, low heat generation property, and abrasion resistance, it can be suitably used as a material for tires, especially for low fuel consumption tires.

Examples

[0114] Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, "parts" is based on weight unless otherwise specified. Also, the tests and evaluations were carried out as follows.

[0115] 〔Molecular weight of rubber〕 The molecular weight of the rubber was determined as the polystyrene equivalent molecular weight by gel permeation chromatography. The specific measurement conditions were as follows. Measuring instrument: High performance liquid chromatograph (manufactured by Tosoh Corporation, trade name "HLC-8320") Column: Two columns of "GMH-HR-H" manufactured by Tosoh Corporation were connected in series. Detector: Differential refractometer (manufactured by Tosoh Corporation, trade name "RI-8320") Eluent: Tetrahydrofuran Column temperature: 40 °C

[0116] 〔Microstructure of Rubber〕 1 It was measured by H-NMR. Measuring instrument: Manufactured by JEOL, product name "JNM-ECA-400WB" Measuring solvent: Deuterated chloroform

[0117] 〔Glass Transition Temperature of Rubber〕 The glass transition temperature (Tg) of the rubber was measured by differential scanning calorimetry (DSC) under the following conditions. Measuring instrument: Pyris1 DSC (manufactured by PerkinElmer) or X-DSC7000 (manufactured by Hitachi High-Tech Sciences Corporation) Heating rate: 10 °C / min Measuring temperature range: -150 °C to +40 °C

[0118] 〔Introduction Rate of Oxy-silyl Group in Terminally Modified Cyclopentene Ring-Opening Polymer Rubber〕 1 By measuring the H-NMR spectrum, the ratio of the peak integral value derived from the oxy-silyl group to the peak integral value derived from the carbon-carbon double bond in the main chain of the terminally modified cyclopentene ring-opening polymer was determined. Based on this ratio of peak integral values and the measured value of the number average molecular weight (Mn) by GPC, the introduction rate of the oxy-silyl group [(percentage of the number of cyclopentene ring-opening polymer chain ends with oxy-silyl groups introduced / number of terminally modified cyclopentene ring-opening polymer chains)] was calculated.

[0119] 〔Tan δ Values Ka(m), Kb(m) of Non-interface Components, Tan δ Values Ka(i), Kb(i) of Interface Components, Ka(i) / Ka(m), Kb(i) / Kb(m), [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]〕 After subjecting the rubber crosslinked product to an extraction treatment in accordance with JIS K6229, for the rubber crosslinked product after the extraction treatment, an ultramicrotome (Leica Microsystems Co., Ltd., Leica EM UC7) was used, and in an atmosphere of -100 °C, a glass knife was used to slice in the thickness direction to prepare test pieces.

[0120] Place the obtained test piece on the sample stage, and for any five locations on the cross-section of the test piece within a range of 1 μm × 1 μm, use an atomic force microscope (manufactured by Bruker, product name "Dimension Icon AFM") at 25°C with a scanning speed of 1 Hz to perform force volume measurement at a resolution of 64 × 64 (resolution of 15.6 nm). Through the cantilever as the measurement probe, measure the elastic modulus, and obtain an elastic modulus image in a field of view of 1 μm × 1 μm. In the measurement, as the measurement probe, a cantilever (manufactured by Olympus, product name "OMCL AC240-TS", spring constant 2 N / m, resonance frequency 70 kHz, tip curvature radius 7 nm) was used. Then, based on the elastic modulus image of the obtained test piece, create a histogram with the elastic modulus X on the horizontal axis and the frequency on the vertical axis, and analyze the created histogram with a Gaussian function to calculate the average value Xm_a and standard deviation σ_a of the elastic modulus based on the elastic modulus peak identified as corresponding to the crosslinked rubber phase (a) derived from the conjugated diene rubber (A), and the average value Xm_b and standard deviation σ_b of the elastic modulus based on the elastic modulus peak identified as corresponding to the crosslinked rubber phase (b) derived from the rubber (B).

[0121] Then, identify the measurement sites where the measured elastic modulus X satisfies Xm_a - 2σ_a ≤ X ≤ Xm_a + 2σ_a as the non-interface-forming crosslinked rubber component part that forms the part other than the interface with silica in the crosslinked rubber phase (a). Also, identify the measurement sites where the measured elastic modulus X satisfies Xm_a + 3σ_a ≤ X ≤ Xm_a + 9σ_a as the interface-forming crosslinked rubber component part that forms the interface with silica in the crosslinked rubber phase (a). Similarly, identify the measurement sites where the measured elastic modulus X satisfies Xm_b - 2σ_b ≤ X ≤ Xm_b + 2σ_b as the non-interface-forming crosslinked rubber component part that forms the part other than the interface with silica in the crosslinked rubber phase (b). Also, identify the measurement sites where the measured elastic modulus X satisfies Xm_b + 3σ_b ≤ X ≤ Xm_b + 9σ_b as the interface-forming crosslinked rubber component part that forms the interface with silica in the crosslinked rubber phase (b).

[0122] Next, for the same field of view of the above test piece, a high-frequency band piezo actuator (manufactured by Noliac, product name "NAC2011-A01") installed on the sample stage independently of the piezoelectric scanner was driven using a lock-in amplifier (Signal Recovery model 7280) to independently generate vibrations by a 10 Hz sine wave with an amplitude of 5 nm. While doing so, for the test piece on the sample stage, using an atomic force microscope (manufactured by Bruker, product name "Dimension Icon AFM"), at 25°C, with a scanning speed of 1 Hz, force volume measurement was performed at a resolution of 64×64 (a resolution of 15.6 nm). Thus, the deformation amount and phase delay of the test piece were measured through the cantilever as the measurement probe, and thereby, a loss tangent image by a 10 Hz sine wave in a 1 μm×1 μm field of view was obtained. In the measurement, as the measurement probe, a cantilever (manufactured by Olympus, product name "OMCL AC240-TS", spring constant 2 N / m, resonance frequency 70 kHz, tip curvature radius 7 nm) was used, and a stationary time was introduced while the cantilever and the test piece were in contact during the force volume measurement, and measurement was performed in a state where vibrations by a 10 Hz sine wave were applied.

[0123] Then, for the loss tangent values K at each measurement site by a 10 Hz sine wave, for each of the non-interface-forming crosslinked rubber component parts and interface-forming crosslinked rubber component parts of the crosslinked rubber phase (a) specified above, and for each of the non-interface-forming crosslinked rubber component parts and interface-forming crosslinked rubber component parts of the crosslinked rubber phase (b), by calculating the average value, the loss tangent values of the non-interface-forming crosslinked rubber component parts, that is, the loss tangent values Ka(m), Kb(m) of the non-interface components forming parts other than the interface with silica, and the loss tangent values of the interface-forming crosslinked rubber component parts, that is, the loss tangent values Ka(i), Kb(i) of the interface components forming the interface with silica were calculated. After that, the ratios Ka(i) / Ka(m), Kb(i) / Kb(m), and the product [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)] of these were determined.

[0124] [Wet grip property] Regarding a test piece of a crosslinked rubber molded to a length of 50 mm, a width of 12.7 mm, and a thickness of 2 mm, using a viscoelasticity measuring device (manufactured by Rheometric Scientific, product name "ARES"), the tanδ at 0 °C was measured under the conditions of a dynamic strain of 0.5% and 10 Hz. The value of this tanδ was shown by an index with the measured value of Comparative Example 1 taken as 100. The smaller this index, the better the wet grip property.

[0125] 〔Low heat generation property〕 Regarding a test piece of a crosslinked rubber molded to a length of 50 mm, a width of 12.7 mm, and a thickness of 2 mm, using a viscoelasticity measuring device (manufactured by Rheometric Scientific, product name "ARES"), the tanδ at 60 °C was measured under the conditions of a dynamic strain of 2.5% and 10 Hz. The value of this tanδ was shown by an index with the measured value of Comparative Example 1 taken as 100. The larger this index, the better the low heat generation property.

[0126] 〔Wear resistance〕 Regarding a test piece of a crosslinked rubber molded to an outer diameter of 50 mm, an inner diameter of 15 mm, and a thickness of 10 mm, using an FPS wear tester (manufactured by Ueshima Seisakusho), the measurement was carried out at a load of 1 kgf and a slip rate of 3%. This property was shown by an index with the measured value of Comparative Example 1 taken as 100. The larger this index, the better the wear resistance.

[0127] 〔Production Example 1〕 〔Production of terminally modified styrene-butadiene rubber (A-1)〕 In a nitrogen atmosphere, 800 g of cyclohexane, 60 g of 1,3-butadiene, 40 g of styrene, and 0.054 g of tetramethylethylenediamine were charged into an autoclave. Then, 0.86 mmol of n-butyllithium was added, and polymerization was initiated at 60°C. The polymerization reaction was continued for 60 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, a modifier represented by the following formula (11) was added in the state of a 20% xylene solution so as to be 0.05 times the molar amount of the n-butyllithium used. After reacting for 30 minutes, 0.064 g of methanol was added as a polymerization terminator to obtain a solution containing a conjugated diene rubber. Then, 0.15 g of 2,4-bis[(octylthio)methyl]-o-cresol (manufactured by Ciba Specialty Chemicals, trade name "Irganox 1520") as an antioxidant was added to 100 g of the obtained polymer component in the solution. After that, the solvent was removed by steam stripping and vacuum dried at 60°C for 24 hours to obtain a solid terminal-modified styrene-butadiene rubber (A-1). The weight average molecular weight (Mw) of the obtained terminal-modified styrene-butadiene rubber (A-1) was 520,000. Also, the content of styrene units in this terminal-modified styrene-butadiene rubber (A-1) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.9°C.

Chemical formula

[0128] [Production Example 2] [Production of Terminal-Modified Styrene-Butadiene Rubber (A-2)] Instead of the modifier represented by the above formula (11), 0.71 g of a modifier represented by the following formula (12) (1.5 times the molar amount relative to the amount of n-butyllithium used) was used without dilution with xylene, and the operation was the same as in Production Example 1 to obtain a solid terminal-modified styrene-butadiene rubber (A-2). The weight average molecular weight (Mw) of the obtained terminal-modified styrene-butadiene rubber (A-2) was 510,000. Further, the content of styrene units in this terminal-modified styrene-butadiene rubber (A-2) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.7 °C.

Chemical formula

[0129] 〔Production Example 3〕 〔Production of terminal-modified styrene-butadiene rubber (A-3)〕 Instead of the modifier represented by the above formula (11), 0.48 g of a modifier represented by the following formula (13) (1.5 times the molar amount relative to the amount of n-butyllithium used) was used without dilution with xylene, and the operation was the same as in Production Example 1 to obtain a solid terminal-modified styrene-butadiene rubber (A-3). The weight average molecular weight (Mw) of the obtained terminal-modified styrene-butadiene rubber (A-3) was 530,000. Further, the content of styrene units in this modified conjugated diene rubber 5 was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.9 °C.

Chemical formula

[0130] 〔Production Example 4〕 〔Production of unmodified styrene-butadiene rubber (A-4)〕 A solid unmodified styrene-butadiene rubber (A-4) was obtained by operating in the same manner as in Production Example 1 except that the modifier represented by the above formula (11) was not blended. The weight average molecular weight (Mw) of the obtained unmodified styrene-butadiene rubber (A-4) was 520,000. Further, the content of styrene units in this unmodified styrene-butadiene rubber (A-4) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.9°C.

[0131] [Production Example 5] [Production of terminally modified styrene-butadiene rubber (A-5)] Instead of the modifier represented by the above formula (11), 0.15 g of tetramethoxysilane as a modifier (1.5 times the molar amount relative to the amount of n-butyllithium used) was used without dilution with xylene, and the operation was carried out in the same manner as in Production Example 1 to obtain a solid terminally modified styrene-butadiene rubber (A-5). The weight average molecular weight (Mw) of the obtained terminally modified styrene-butadiene rubber (A-5) was 520,000. Further, the content of styrene units in this terminally modified styrene-butadiene rubber (A-5) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.5°C.

[0132] [Production Example 6] [Production of unmodified styrene-butadiene rubber (A-6)] A solid unmodified styrene-butadiene rubber (A-6) was obtained by operating in the same manner as in Production Example 4 except that the amount of tetramethylethylenediamine used was changed to 0.0027 g and the amount of n-butyllithium used was changed to 0.52 mmol. The weight average molecular weight (Mw) of the obtained unmodified styrene-butadiene rubber (A-6) was 1,010,000. Further, the content of styrene units in this unmodified styrene-butadiene rubber (A-6) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.7°C.

[0133] [Production Example 7] [Production of unmodified styrene-butadiene rubber (A-7)] The procedure of Production Example 4 was repeated except that the amount of tetramethylethylenediamine used was changed to 0.23 g, to obtain a solid unmodified styrene-butadiene rubber (A-7). The weight average molecular weight (Mw) of the obtained unmodified styrene-butadiene rubber (A-7) was 530,000. The content of styrene units in this unmodified styrene-butadiene rubber (A-7) was 40% by weight, the vinyl bond content in the butadiene units was 35 mol%, and the glass transition temperature was -0.5°C.

[0134] [Production Example 8] [Production of terminally modified styrene-butadiene rubber (A-8)] Instead of the modifier represented by the above formula (11), 0.076 g of tetramethoxysilane as a modifier (1.5 times the molar amount relative to the amount of n-butyllithium used) was used without dilution with xylene, and the amount of tetramethylethylenediamine used was changed to 0.027 g and the amount of n-butyllithium used was changed to 0.52 mmol. Otherwise, the procedure of Production Example 1 was repeated to obtain a solid terminally modified styrene-butadiene rubber (A-8). The weight average molecular weight (Mw) of the obtained terminally modified styrene-butadiene rubber (A-8) was 1,050,000. The content of styrene units in this terminally modified styrene-butadiene rubber (A-8) was 40% by weight, the vinyl bond content in the butadiene units was 10 mol%, and the glass transition temperature was -21.6°C.

[0135] [Production Example 9] [Production of terminally modified styrene-butadiene rubber (A-9)] Instead of the modifier represented by the above formula (11), 0.152 g of tetramethoxysilane as a modifier (1.5 times the molar amount relative to the amount of n-butyllithium used) was used without dilution with xylene, and the amount of tetramethylethylenediamine used was changed to 0.155 g. Otherwise, the same operations as in Production Example 1 were carried out to obtain a solid terminal-modified styrene-butadiene rubber (A-9). The weight-average molecular weight (Mw) of the obtained terminal-modified styrene-butadiene rubber (A-9) was 520,000. Further, the content of styrene units in this terminal-modified styrene-butadiene rubber (A-9) was 40% by weight, the vinyl bond content in the butadiene units was 35 mol%, and the glass transition temperature was -0.6°C.

[0136] [Production Example 10] [Production of Terminal-Modified Polybutadiene Rubber (B-1)] Into an autoclave equipped with a stirrer, 5670 g of cyclohexane and 700 g of 1,3-butadiene were charged under a nitrogen atmosphere. Then, an amount of n-butyllithium necessary for neutralizing impurities that inhibit the polymerization contained in cyclohexane and 1,3-butadiene was added, and further 8.33 mmol of n-butyllithium as the amount used for the polymerization reaction was added, and the polymerization was started at 50°C. After 20 minutes had elapsed since the start of the polymerization, 300 g of 1,3-butadiene was continuously added over 30 minutes. The maximum temperature during the polymerization reaction was 80°C. After the continuous addition was completed, the polymerization reaction was further continued for 15 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.333 mmol of 1,6-bis(trichlorosilyl)hexane (equivalent to 0.04 times the molar amount of n-butyllithium used in the polymerization) was added to the polymerization solution in the state of a 40 wt% cyclohexane solution, and the reaction was carried out for 30 minutes. Further, thereafter, 2.92 mmol of the modifier represented by the above formula (11) (equivalent to 0.35 times the molar amount of n-butyllithium used in the polymerization) was added in the state of a 20 wt% xylene solution, and the reaction was carried out for 30 minutes. Then, 8.33 mmol of tetramethoxysilane (equivalent to 1 times the molar amount of n-butyllithium used in the polymerization) was added in the state of a 25 wt% cyclohexane solution, and the reaction was carried out for 30 minutes. Thereafter, as a polymerization terminator, an amount of methanol equivalent to 2 times the molar amount of n-butyllithium used was added to obtain a solution containing the end-modified polybutadiene rubber (B-1). Then, to the obtained solution, 0.2 part of Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an antioxidant was added per 100 parts of the rubber component, and after removing the solvent by steam stripping, vacuum drying was carried out at 60 °C for 24 hours to obtain the end-modified polybutadiene rubber (B-1). The weight average molecular weight (Mw) of the obtained end-modified polybutadiene rubber (B-1) was 553,000, and it substantially did not contain styrene units. The vinyl / cis / trans ratio was vinyl / cis / trans = 10 / 45 / 45, and the glass transition temperature (Tg) was -80 °C.

[0137] [Production Example 11] [Production of End-Modified Cyclopentene Ring-Opening Polymer Rubber (B-2)] Under a nitrogen atmosphere, 588 parts of a 1.5 wt% WCl6 / toluene solution and 252 parts of a 3.75 wt% diisobutylaluminum mono(n-hexoxide) / toluene solution prepared in Reference Example 1 were added to a glass container containing a stir bar, and the mixture was stirred for 15 minutes to obtain a catalyst solution. Then, under a nitrogen atmosphere, 3056 parts of cyclopentene and 11.2 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 840 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 25°C for 4 hours. After the 4-hour polymerization reaction, an excessive amount of ethyl alcohol was added to the pressure-resistant glass reaction vessel to terminate the polymerization. Then, as an antioxidant, Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added in an amount of 0.2 part per 100 parts of the polymer obtained by polymerization. Subsequently, the polymer was coagulated with a large amount of ethanol and recovered, and vacuum-dried at 40°C for 3 days to obtain 458 parts of a terminal-modified cyclopentene ring-opening polymer rubber (B-2) with both ends modified. The weight-average molecular weight (Mw) of the obtained terminal-modified cyclopentene ring-opening polymer rubber (B-2) was 500,000, substantially free of styrene units, the cis / trans ratio was cis / trans = 55 / 45, the glass transition temperature (Tg) was -105°C, and the oxy-silyl group introduction rate was 175%.

[0138] [Production Example 12] [Production of Terminal-Modified Cyclopentene Ring-Opening Polymer Rubber (B-3)] Under a nitrogen atmosphere, 88 parts of toluene and 11.7 parts of a 25.4 wt% triisobutylaluminum / n-hexane solution (manufactured by Tosoh Finechem Corporation) were added to a glass container containing a stir bar. Next, the container was cooled to -45°C, and 1.53 parts of n-hexanol (equimolar amount relative to triisobutylaluminum) was slowly added dropwise while stirring vigorously. Then, the mixture was allowed to stand at room temperature while stirring to prepare a diisobutylaluminum mono(n-hexoxide) / toluene solution (3.75 wt%). Next, under a nitrogen atmosphere, 588 parts of a 1.5 wt% WCl6 / toluene solution and 252 parts of a 3.75 wt% diisobutylaluminum mono(n-hexoxide) / toluene solution prepared above were added to a glass container containing a stir bar, and the mixture was stirred for 15 minutes to obtain a catalyst solution. Then, under a nitrogen atmosphere, 1531 parts of cyclopentene, 1003 parts of toluene, and 9.8 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 840 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 25 °C for 4 hours. After the 4-hour polymerization reaction, an excessive amount of ethyl alcohol was added to the pressure-resistant glass reaction vessel to terminate the polymerization. Then, as an antioxidant, Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added in an amount of 0.2 part per 100 parts of the polymer obtained by polymerization. Next, the polymer was recovered by coagulation with a large amount of ethanol and vacuum-dried at 40 °C for 3 days to obtain 183 parts of a terminally modified cyclopentene ring-opening polymer rubber (B-3) with both ends modified. The weight average molecular weight (Mw) of the obtained terminally modified cyclopentene ring-opening polymer rubber (B-3) was 500,000, it substantially did not contain styrene units, the cis / trans ratio was cis / trans = 35 / 65, the glass transition temperature (Tg) was -104 °C, and the oxy-silyl group introduction rate was 172%.

[0139] [Production Example 13] [Production of terminally modified cyclopentene ring-opening polymer rubber (B-4)] Under a nitrogen atmosphere, 588 parts of a 1.5 wt% WCl6 / toluene solution and 252 parts of a 3.75 wt% diisobutylaluminum mono(n-hexoxide) / toluene solution prepared in the same manner as in Production Example 12 were added to a glass container containing a stir bar, and the mixture was stirred for 15 minutes to obtain a catalyst solution. Then, under a nitrogen atmosphere, 3012 parts of cyclopentene and 3.8 parts of vinyltriethoxysilane were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 840 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 25°C for 4 hours. After the 4-hour polymerization reaction, an excessive amount of ethyl alcohol was added to the pressure-resistant glass reaction vessel to terminate the polymerization, and then, as an antioxidant, Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added in an amount of 0.2 part per 100 parts of the polymer obtained by polymerization. Subsequently, the polymer was recovered by coagulation with a large amount of ethanol and vacuum-dried at 40°C for 3 days to obtain 633 parts of a terminally modified cyclopentene ring-opening polymer rubber (B-4) with one end modified. The weight-average molecular weight (Mw) of the obtained terminally modified cyclopentene ring-opening polymer rubber (B-4) was 513,000, substantially free of styrene units, the cis / trans ratio was cis / trans = 55 / 45, the glass transition temperature (Tg) was -105°C, and the oxy-silyl group introduction rate was 92%.

[0140] [Production Example 14] [Production of Unmodified Cyclopentene Ring-Opening Polymer Rubber (B-5)] Under a nitrogen atmosphere, 588 parts of a 1.5 wt% WCl6 / toluene solution and 252 parts of a 3.75 wt% diisobutylaluminum mono(n-hexoxide) / toluene solution prepared in the same manner as in Production Example 12 were added to a glass container containing a stir bar, and the mixture was stirred for 15 minutes to obtain a catalyst solution. Then, under a nitrogen atmosphere, 3158 parts of cyclopentene and 7.1 parts of 1-hexene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 840 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 0 °C for 4 hours. After the 4-hour polymerization reaction, an excess of ethyl alcohol was added to the pressure-resistant glass reaction vessel to stop the polymerization, and then, as an antioxidant, Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added in an amount of 0.2 part per 100 parts of the polymer obtained by polymerization. Subsequently, the polymer was recovered by coagulation with a large amount of ethanol and vacuum-dried at 40 °C for 3 days to obtain 1092 parts of an unmodified cyclopentene ring-opening polymer rubber (B-5). The weight average molecular weight (Mw) of the obtained unmodified cyclopentene ring-opening polymer rubber (B-5) was 250,000, it substantially did not contain styrene units, the cis / trans ratio was cis / trans = 77 / 23, and the glass transition temperature (Tg) was -108 °C.

[0141] [Production Example 15] [Production of Unmodified Cyclopentene Ring-Opening Polymer Rubber (B-6)] Under a nitrogen atmosphere, 588 parts of a 1.5 wt% WCl6 / toluene solution and 252 parts of a 3.75 wt% diisobutylaluminum mono(n-hexoxide) / toluene solution prepared in the same manner as in Production Example 12 were added to a glass container containing a stir bar, and the mixture was stirred for 15 minutes to obtain a catalyst solution. Then, under a nitrogen atmosphere, 3210 parts of cyclopentene and 2.5 parts of 1-hexene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 840 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 0 °C for 4 hours. After the 4-hour polymerization reaction, an excessive amount of ethyl alcohol was added to the pressure-resistant glass reaction vessel to terminate the polymerization. Then, as an antioxidant, 0.2 part of Irganox 1520L (manufactured by Ciba Specialty Chemicals) was added per 100 parts of the polymer obtained by polymerization. Next, the polymer was recovered by coagulation with a large amount of ethanol and vacuum-dried at 40 °C for 3 days to obtain 1245 parts of an unmodified cyclopentene ring-opening polymer rubber (B-6). The weight average molecular weight (Mw) of the obtained unmodified cyclopentene ring-opening polymer rubber (B-6) was 500,000, substantially free of styrene units, the cis / trans ratio was cis / trans = 75 / 25, and the glass transition temperature (Tg) was -108 °C.

[0142] [Example 1] In a Brabender type mixer with a capacity of 250 ml, 70 parts of the terminal-modified styrene-butadiene rubber (A-1) obtained in Production Example 1 and 30 parts of natural rubber were kneaded for 30 seconds. Then, 23 parts of silica (manufactured by Solvay, trade name "Zeosil1165MP") and 6.4 parts of a silane coupling agent: bis(3-(triethoxysilyl)propyl)tetrasulfide (manufactured by Evonik, trade name "Si69") were added. After kneading for 1.5 minutes starting from 110°C, 27 parts of silica (manufactured by Solvay, trade name "Zeosil1165MP"), 3 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "No Crack 6C") were added, and kneading was continued for another 2.5 minutes. Then, the kneaded material was discharged from the mixer. The temperature of the kneaded material at the end of kneading was 150°C. Then, after cooling the obtained kneaded material to room temperature, it was kneaded again in a Brabender type mixer for 2 minutes starting from 110°C, and then the kneaded material was discharged from the mixer. Next, on an open roll at 50°C, 1.5 parts of sulfur, 1.8 parts of a crosslinking accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide (trade name "Nocceler CZ-G", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and 1.5 parts of a crosslinking accelerator: 1,3-diphenylguanidine (trade name "Nocceler D", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added to the obtained kneaded material and kneaded, and then a sheet-like rubber composition was taken out.

[0143] Next, the obtained rubber composition was press-cured at 160°C for 20 minutes to prepare a test piece of the rubber crosslinked product. For this test piece, when a vibration by a sine wave of 10 Hz was applied, the loss tangent values Ka(m), Kb(m) of the non-interface components, and the loss tangent values Ka(i), Kb(i) of the interface components in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B), as well as the ratios Ka(i) / Ka(m), Kb(i) / Kb(m) of these, and the product [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)] of these were measured, and the wet grip property, low heat generation property, and abrasion resistance were evaluated. The results are shown in Table 2.

[0144] [Examples 2 to 18, Comparative Examples 1 to 8] As the conjugated diene rubber (A) and the rubber (B), those shown in Table 2 were used in the same amounts as in Example 1, and a sheet-like rubber composition and a rubber crosslinked product were obtained and evaluated in the same manner as in Example 1, except for this. The results are shown in Table 2. As shown in Table 2, in Examples 2 to 18 and Comparative Examples 1 to 8, each rubber obtained in Production Examples 1 to 9 was used as the conjugated diene rubber (A). Further, in Examples 2, 6, 10 and Comparative Examples 1 to 6, polybutadiene rubber (trade name "Nipol BR1220", manufactured by Zeon Corporation, Japan) was used as the rubber (B), and in Examples 5 and 9, the same natural rubber as that used in Example 1 was used as the rubber (B). In other Examples and Comparative Examples, each rubber obtained in Production Examples 10 to 15 was used as the rubber (B).

[0145] [Table 1]

[0146] [Table 2]

[0147] From Tables 1 and 2, when vibration was applied by a sine wave at 10 Hz, in the crosslinked rubber phase (a) derived from the conjugated diene rubber (A) and the crosslinked rubber phase (b) derived from the rubber (B), the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components satisfied the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87. All of the rubber crosslinked products were excellent in wet grip property, low heat build-up property and abrasion resistance (Examples 1 to 18). On the other hand, when the loss tangent values Ka(m), Kb(m) of the non-interface components and the loss tangent values Ka(i), Kb(i) of the interface components did not satisfy the relationship of [Ka(i) / Ka(m)]×[Kb(i) / Kb(m)]≦0.87, all of them were inferior in wet grip property (Comparative Examples 1 to 8).

Claims

1. A rubber crosslinked product obtained by crosslinking a rubber composition containing only a conjugated diene rubber (A) having an aromatic vinyl monomer unit and a conjugated diene monomer unit, wherein the content ratio of the aromatic vinyl monomer unit is 20% by weight or more, and the vinyl bond content in the conjugated diene monomer unit is 0 to 35 mol%, a rubber (B) having a content ratio of the aromatic vinyl monomer unit of 5% by weight or less, an inorganic filler (C), a crosslinking agent, and at least one compounding agent selected from the group consisting of a crosslinking accelerator, a crosslinking activator, an antioxidant, an organic filler, an activator, a process oil, a plasticizer, a lubricant, a tackifier, and a silane coupling agent, wherein the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group, the rubber (B) is a modified cyclopentene ring-opening polymer rubber having a modifying group, the content ratio of the conjugated diene rubber (A) and the rubber (B) is 80:20 to 50:50 in terms of the weight ratio of "conjugated diene rubber (A): rubber (B)", the content of the inorganic filler (C) is 10 to 200 parts by weight with respect to 100 parts by weight of the rubber component including the conjugated diene rubber (A) and the rubber (B) in the rubber composition, and the content of the crosslinking agent is 0.1 to 15 parts by weight with respect to 100 parts by weight of the rubber component including the conjugated diene rubber (A) and the rubber (B) in the rubber composition.

2. The rubber crosslinked product according to Claim 1, wherein the glass transition temperature (Tg) of the conjugated diene rubber (A) is -40°C or higher, and the glass transition temperature (Tg) of the rubber (B) is -60°C or lower.

3. The rubber crosslinked product according to Claim 1 or 2, wherein the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group derived from a silicon atom-containing modifying agent.

4. The rubber crosslinked product according to Claim 3, wherein the conjugated diene rubber (A) is a modified conjugated diene rubber having a modifying group derived from a siloxane compound or a nitrogen-containing silane compound.

5. The rubber crosslinked product according to any one of Claims 1 to 4, wherein the inorganic filler (C) is silica.

6. A tire comprising the rubber crosslinked product according to any one of Claims 1 to 5.

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