CROSS-LINKED RUBBER COMPOSITION

Abstract

Task: To provide a crosslinked rubber composition exhibiting low dynamic magnification and excellent performance stability with small changes in properties upon repeated deformation. Solution agent: Crosslinked rubber composition containing a rubber component comprising at least one conjugated diene-based polymer, as well as carbon black and sulfur, where - the storage modulus after deformation ΔG' = G' (0.1% deformation) - G' (10% deformation) is 3.0 MPa or less, - when the storage modulus is measured twice after deformation, the difference in the storage modulus G' (0.1% deformation) between the two measurements is 0.4 MPa or less and the difference in the storage modulus G' (10% deformation) between the two measurements is 0.2 MPa or less, and - when the storage modulus is measured twice after deformation, the rate of change of the storage modulus G' between the two measurements at 0.1% deformation and between the two measurements at 10% deformation is 6.0% or less, with the following calculation formulas: Difference of G' ( 0.1 % deformation ) between the two measurements = G' at the first measurement − G' at the second measurement Difference of G' ( 10 % deformation ) between the two measurements = G' at the first measurement − G' at the second measurement Rate of change of G' = ( Difference of G ' ( 0.1 % deformation ) between the two measurements / G' at the first measurement ) × 100 Rate of change of G' = ( Difference of G ' ( 10 % strain ) between the two measurements / G' at the first measurement ) × 100.

Description

TECHNICAL FIELD

[0001] The present invention relates to a crosslinked rubber composition comprising a rubber component comprising at least one kind of conjugated diene-based polymer, carbon black and sulfur. BACKGROUND TECHNOLOGY

[0002] In vulcanized crosslinked rubber compositions for use in vibration-damping rubber and industrial materials, etc., carbon black containing natural rubber is mainly used as a rubber material or filler, which generally has excellent anti-vibration performance and rubber reinforcing properties (see, for example, JP 2018-35253 A and JP 2007-70582 A).

[0003] In recent years, various techniques that introduce a predetermined functional group to the terminal of a conjugated diene-based polymer have been proposed as a method for improving the performance of vulcanized crosslinked rubber compositions in these fields (see, for example, JP H05-202102 and JP 2023-519535).

[0004] In addition, there is also a need for improving the dynamic magnification, which is anti-vibration performance, and durability of vibration damping rubber. OVERVIEW OF THE INVENTION OBJECT TO BE SOLVED BY THE INVENTION

[0005] For vibration damping rubber used in engine mounts, suspension bushings, etc., which support the engine of a car, etc. and suppress the transmission of vibrations, there is a need to provide a cross-linked rubber composition that has low dynamic magnification and excellent performance stability with small changes in properties upon repeated deformation. MEANS FOR SOLVING THE TASK

[0006] The present inventors have intensively considered in order to solve the above-described problems of the prior art and found that a crosslinked rubber composition comprising a rubber component comprising at least one kind of conjugated diene-based polymer, carbon black, and sulfur, wherein the storage modulus after deformation ΔG' is 3.0 MPa or less, and the difference and the change rate of the storage modulus G' in twice-measured storage modulus after deformation are set within a certain range, has a small dynamic magnification and excellent performance stability with small changes in properties upon repeated deformation, and completed the present invention.

[0007] That is, the present invention is as follows: [1] A crosslinked rubber composition comprising a rubber component comprising at least one conjugated diene-based polymer, carbon black and sulfur, wherein - the storage modulus after deformation ΔG' = G' (0.1% deformation) - G' (10% deformation) is 3.0 MPa or less, - when the storage modulus is measured twice after deformation, the difference in the storage modulus G' (0.1% deformation) between the two measurements is 0.4 MPa or less and the difference in the storage modulus G' (10% deformation) between the two measurements is 0.2 MPa or less, and - when the storage modulus is measured twice after deformation, the rate of change of the storage modulus G' between the two measurements at 0.1% deformation and between the two measurements at 10% deformation is 6.0% or less, using the following calculation formulas: Difference of G' (0.1% deformation) between the two measurements = G' at the first measurement - G' at the second measurement Difference of G' (10% deformation) between the two measurements = G' at the first measurement - G' at the second measurement Rate of change of G' = (Difference of G' (0.1% deformation) between the two measurements / G' at the first measurement) × 100 Rate of change of G' = (Difference of G' (10% strain) between the two measurements / G' at the first measurement) × 100. [2] Crosslinked rubber composition according to item [1], wherein the volume fraction of carbon black in the crosslinked rubber composition is 7 to 30 vol%. [3] The crosslinked rubber composition according to item [1] or [2], wherein the glass transition temperature of the conjugated diene-based polymer is -110°C to -80°C. [4] The crosslinked rubber composition according to any one of [1] to [3], wherein the 1,2-vinyl bond amount in the conjugated diene monomer unit of the conjugated diene-based polymer is 10 mol% or more and 25 mol% or less. [5] The crosslinked rubber composition according to any one of [1] to [2], wherein the aromatic vinyl monomer unit content of the conjugated diene-based polymer is 0 mass% or more and 7 mass% or less. [6] The crosslinked rubber composition according to any one of items [1] to [5], wherein the conjugated diene-based polymer is a modified conjugated diene-based polymer obtained by reacting a modifier that reacts with an active terminal with at least one >C=O group and at least one substituted amino group in one molecule, or a modified conjugated diene-based polymer obtained by reacting a nitrogen atom-containing coupling agent having four or more functional groups in one molecule that react with an active terminal not having a halogen and a modifier that reacts with an active terminal with at least one >C=O group and at least one substituted amino group in one molecule. [7] The crosslinked rubber composition according to any one of [1] to [6], wherein the degree of modification of the modified conjugated diene-based polymer obtained by reacting the modifier with at least one >C=O group and at least one substituted amino group in a molecule which react with the active terminal, measured by column adsorption GPC method, is 50% or more and 99% or less. [8] The crosslinked rubber composition according to item [6] or [7], wherein the coupling degree of the modified conjugated diene-based polymer obtained by a nitrogen atom-containing coupling agent having four or more functional groups in one molecule which react with the active terminal having no halogen is 7% or more and 25% or less. [9] The crosslinked rubber composition according to any one of [6] to [8], wherein the coupling degree of the modified conjugated diene-based polymer obtained by a nitrogen atom-containing coupling agent having four or more functional groups in one molecule which react with the active terminal having no halogen is 7% or more and 15% or less.

[10] The crosslinked rubber composition according to any one of [1] to [9], wherein the tin content of the conjugated diene-based polymer is 20 ppm or less.

[11] Crosslinked rubber composition according to any one of items [1] to

[10] , wherein the filler in the crosslinked rubber composition is exclusively carbon black.

[12] Vibration damping rubber comprising the crosslinked rubber composition according to any one of items [1] to

[11] .

[13] Power transmission belts and conveyor belts comprising the crosslinked rubber composition according to any one of [1] to

[11] . EFFECTS OF THE INVENTION

[0008] The crosslinked rubber composition of the present invention achieves the effect of low dynamic magnification and low performance degradation upon repeated deformation (improvement of dynamic magnification and performance stability). The vibration-damping rubber formed from the crosslinked rubber composition of the present invention is suitable for use as a vibration-damping material for engine mounts, stabilizer bushings, suspension bushings, etc., used in automobiles.In addition, it can also be used for applications such as vibration isolators for computer hard drives, vibration isolators for general household appliances such as washing machines, as well as vibration control devices (vibration damping) such as vibration control walls and vibration control dampers (vibration damping) and seismic isolation devices in the field of architecture and housing. EMBODIMENTS OF THE INVENTION

[0009] In the following, embodiments of the present invention (hereinafter referred to as "present embodiment(s)") will be explained in detail, but the present invention is not limited to them, and various modifications are possible as long as they do not deviate from the gist of the present invention. <Vernetzte Kautschukzusammensetzung>

[0010] The crosslinked rubber composition of the present embodiment is a crosslinked rubber composition comprising a rubber component comprising at least one kind of conjugated diene-based polymer, carbon black (or carbon black) and sulfur, wherein the storage modulus after deformation ΔG' = G' (0.1% deformation) - G' (10% deformation) from the perspective of a low dynamic magnification is 3.0 MPa or less, preferably 2.8 MPa or less, and more preferably 2.5 MPa or less.

[0011] Furthermore, in the crosslinked rubber composition of the present embodiment, when the storage modulus is measured twice after deformation from a low dynamic magnification perspective, the difference in the storage modulus G' (0.1% deformation) is 0.40 MPa or less, more preferably 0.30 MPa or less, and even more preferably 0.20 MPa or less, and the difference in the storage modulus G' (10% deformation) is 0.20 MPa or less, more preferably 0.17 MPa or less, and even more preferably 0.15 MPa or less when the storage modulus is measured twice after deformation from a low dynamic magnification perspective. Furthermore, when the storage modulus is measured twice after deformation, the change rate of the storage modulus G' at 0.1% deformation and at 10% deformation is 6.0% or less, more preferably 5.6% or less, and even more preferably 5.0% or less when the performance stability of the crosslinked rubber composition is considered.

[0012] The difference of storage modulus G' (0.1% deformation) when measuring the storage modulus twice after deformation, the difference of storage modulus G' (10% deformation) and the rate of change of storage modulus G' at 0.1% deformation and 10% deformation when measuring the storage modulus twice after deformation can be calculated by the following calculation formulas: Difference of G' (0.1% deformation) between the two measurements = G' at the first measurement − G' at the second measurement Difference of G' (10% deformation) between the two measurements = G' at the first measurement − G' at the second measurement Rate of change of G'=(Difference of G'(0.1% deformation) between the two measurements / G' at the first measurement)×100 Rate of change of G'=(Difference of G'(10% strain) between the two measurements / G' at the first measurement)×100.

[0013] The difference and the rate of change of the storage modulus G' described above can be controlled by adjusting the composition and various parameters of the conjugated diene-based polymer described later.

[0014] From the perspective of low dynamic magnification and performance stability, the crosslinked rubber composition of the present embodiment comprises a rubber component containing at least one conjugated diene-based polymer, and the proportion of natural rubber in the total amount (100 parts by mass) of the rubber component is preferably 50 to 90 mass%, and more preferably in the range of 50 to 70 mass%. Furthermore, from the perspective of improving the dispersibility of carbon black in the crosslinked rubber composition, the proportion of the at least one conjugated diene-based polymer in the rubber component is preferably 10 to 50 mass%, and more preferably in the range of 30 to 50 mass%.

[0015] In the crosslinked rubber composition of the present embodiment, due to the presence of a certain amount of the specific modified conjugated diene-based polymer described later, it is possible to achieve good dispersion of carbon black even when a relatively large amount of carbon black is blended.

[0016] From the perspective of the reinforcing effect and workability, the volume fraction of carbon black in the crosslinked rubber composition of the present embodiment is preferably 7 to 30 vol%, more preferably 8 to 25 vol%, and even more preferably in the range of 10 to 20 vol%. If the blending amount of carbon black is too small, the reinforcing effect tends to be poor, and, conversely, if the blending amount of carbon black is too large, the dynamic magnification tends to be high and the viscosity tends to increase, resulting in deterioration in workability. [Conjugated diene-based polymer]

[0017] The conjugated diene-based polymer of the present embodiment contains at least one type of conjugated diene compound and may also contain an aromatic vinyl compound. The conjugated diene-based polymer of the present embodiment may be a polymer composed of a structural unit derived from a conjugated diene compound (hereinafter also referred to as a "conjugated diene monomer unit"), or a copolymer formed from or consisting of a structural unit derived from an aromatic vinyl compound (hereinafter also referred to as an "aromatic vinyl monomer unit") and the conjugated diene monomer unit.

[0018] The conjugated diene-based polymer of the present embodiment is preferably a copolymer of a conjugated diene compound and an aromatic vinyl compound in which the so-called microstructure (content of aromatic vinyl monomer unit, the 1,2-vinyl bond amount, etc.) is controlled.

[0019] In the conjugated diene-based polymer of the present embodiment, it is preferable that the aromatic vinyl monomer unit content is 0 mass% or more and 7 mass% or less, and the 1,2-vinyl bond amount in the conjugated diene monomer unit is 10 mol% or more and 25 mol% or less.

[0020] Aromatic vinyl compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred due to its ease of industrial procurement. These can be used individually or in combination with two or more types.

[0021] In addition, conjugated diene compounds include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the perspective of ease of industrial procurement, and 1,3-butadiene is particularly preferred. These can be used individually or in combination with two or more types. (Content of aromatic vinyl monomer unit)

[0022] The content of the aromatic vinyl monomer unit in the conjugated diene-based polymer of the present embodiment is preferably 7 mass% or less, more preferably 5 mass% or less, even more preferably 3 mass% or less, particularly preferably 1 mass% or less, and may also be 0 mass% from the perspective of improving the dynamic magnification of the crosslinked rubber composition.

[0023] The content of aromatic vinyl monomer units can be measured by 1H NMR. Specifically, it can be measured using the method described in the working examples.

[0024] The content of aromatic vinyl monomer unit can be controlled to the above numerical range by adjusting the amount of aromatic vinyl compound added in the polymerization. (1,2-vinyl bond amount)

[0025] The 1,2-vinyl bond amount in the conjugated diene-based polymer of the present embodiment is the molar ratio of the 1,2-vinyl bond amount to the conjugated diene monomer unit content. From the perspective of the productivity of the conjugated diene-based polymer, it is preferably 10 mol% or more, more preferably 13 mol% or more, and even more preferably 14 mol% or more. On the other hand, from the perspective of improving the dynamic magnification and tensile properties of the conjugated diene-based polymer of the present embodiment and also from the perspective of suppressing gelation of the conjugated diene-based polymer, it is 25 mol% or less, preferably 22 mol% or less, more preferably 21 mol% or less, and even more preferably 20 mol% or less.

[0026] The amount of 1,2-vinyl bond can be measured by 1H NMR. Specifically, it can be measured using the method described in the working examples.

[0027] The 1,2-vinyl bond amount can be controlled to the above numerical range by adjusting the reaction start temperature and reaction end temperature in polymerization and the type and amount of the added polar substance. (Weight average molecular weight Mw in GPC measurement)

[0028] When measuring the conjugated diene-based polymer of the present embodiment by GPC (gel permeation chromatography), the weight-average molecular weight Mw of the entire conjugated diene-based polymer (including the coupling portion, if coupled) is preferably 300,000 or more, and more preferably 350,000 or more from the perspective of productivity and cold flow properties of the conjugated diene-based polymer. From the perspective of suppressing gelation, it is preferably 1,000,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less. (Mooney viscosity)

[0029] In the conjugated diene-based polymer of the present embodiment, the Mooney viscosity measured at 100°C is preferably 30 or more and 120 or less, more preferably 35 or more and 100 or less, and even more preferably 40 or more and 90 or less, from the perspective of productivity and cold flow properties of the conjugated diene-based polymer, processability as a rubber composition in which a filler such as carbon black is blended, and tensile strength, elongation, and hardness as a crosslinked rubber composition obtained by vulcanizing the composition.

[0030] A Mooney viscosity of 30 or more measured at 100°C tends to improve the tensile strength and elongation of the vulcanized crosslinked rubber composition, and a Mooney viscosity of 120 or less measured at 100°C tends to improve the workability of the rubber composition into which a filler such as carbon black is blended.

[0031] The Mooney viscosity of the conjugated diene-based polymer can be measured by the method given in the embodiment described later.

[0032] The Mooney viscosity can be controlled by the microstructure of the conjugated diene-based polymer, the weight average molecular weight Mw and the coupling ratio through the coupling reaction described below. (glass transition temperature)

[0033] The glass transition temperature of the conjugated diene-based polymer of the present embodiment is preferably -80°C or less, more preferably -82°C or less, even more preferably -84°C or less, and particularly preferably -86°C or less, from the perspective of dynamic magnification and low-temperature properties. On the other hand, from the perspective of polymerization reproducibility in living anionic polymerization, it is preferably -110°C or more, more preferably -108°C or more, and even more preferably -106°C or more.

[0034] The glass transition temperature can be measured by the method given in the embodiments described later.

[0035] As a method for controlling the glass transition temperature within a certain range, the control can be performed depending on the ratio of the conjugated diene monomer unit to the aromatic vinyl monomer unit in the conjugated diene-based polymer and the 1,2-vinyl bond amount, and the 1,2-vinyl bond amount can be controlled by the amount of polar substances added during polymerization and the polymerization temperature. (Coupling)

[0036] The conjugated diene-based polymer of the present embodiment may be a conjugated diene-based polymer obtained by carrying out a coupling reaction using a reactive compound having two or more functional groups (hereinafter also referred to as “coupling agent”) at the active end of the conjugated diene-based polymer obtained by the polymerization step.

[0037] In the coupling reaction step, a coupling agent is used at one end of the active end of the conjugated diene-based polymer to carry out a coupling reaction and obtain a conjugated diene-based polymer.

[0038] The coupling agent includes, for example, although there is no particular limitation, coupling agents having one or more functional groups such as an epoxy group, a carbonyl group, a carboxylic acid ester group, a carboxamide group, an acid anhydride group, a phosphate ester group, a phosphite ester group, an epithio group, a thiocarbonyl group, a thiocarboxylic acid ester group, a dithiocarboxylic acid ester group, a thiocarboxylic acid amide group, an imino group, an ethyleneimino group, a halogen group, an alkoxysilyl group, an isocyanate group, a thiocyanate group, a conjugated diene group, and an arylvinyl group. Among the coupling agents, a nitrogen atom-containing coupling agent can also be used as a modifier described below.

[0039] The coupling agent includes, for example, but is not limited to: halogenated silane compounds such as silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, monomethyltrichlorosilane, monoethyltrichlorosilane, monobutyltrichlorosilane, monohexyltrichlorosilane, monomethyltribromosilane, bistrichlorosilylethane, alkoxyhalogenated silane compounds such as monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxysilane, dibromodimethoxysilane, trichloromethoxysilane, tribromommethoxysilane, etc.

[0040] In addition, these include, for example, but not exclusively: alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, alkyltriphenoxysilane, compounds with imino groups and alkoxysilyl groups, etc. such as tristrimethoxysilylpropylamine, triethoxysilylpropylamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(tributoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole, etc.

[0041] Außerdem gehören dazu bspw., jedoch nicht ausschließlich: 2-[3-(Trimethoxysilyl)propyl]-1,3-dimethylimidazolidin, 2-[3-(Trimethoxysilyl)propyl]-1,3-(bistrimethylsilyl)imidazolidin, 2-(Diethoxydiethylsilyl)-1,3-diethylimidazolidin, 2-(Triethoxysilyl)-1,4-diethylpiperazin, 2-(Dimethoxymethylsilyl)-1,4-dimethylpiperazin, 5-(Triethoxysilyl)-1,3-dipropylhexahydropyrimidin, 5-(Diethoxyethylsilyl)-1,3-diethylhexahydropyrimidin, {2-[3-(2-Dimethylaminoethyl)-2-(ethyldimethoxysilyl)-imidazolidin-1-yl]-ethyl}-dimethylamin, 5-(Trimethoxysilyl)-1,3-bis-(2-methoxyethyl)-hexahydropyrimidin, 5-(Ethyldimethoxysilyl)-1,3-bis-(2-trimethylsilylethyl)-hexahydropyrimidin-1,3-dimethylimidazolidin, 2-(3-Diethoxyethylsilyl-propyl)-1,3-diethylimidazolidin, 2-(3-Triethoxysilyl-propyl)-1,4-diethylpiperazin, 2-(3-Dimethoxymethylsilyl-propyl)-1,4-dimethylpiperazin, 5-(3-Triethoxysilyl-propyl)-1,3-dipropylhexahydropyrimidin, 5-(3-Diethoxyethylsilylpropyl)-1,3-diethylhexahydropyrimidin,{2-[3-(2-Dimethylaminoethyl)-2-(3-ethyldimethoxysilyl-propyl)-imidazolidin-1-yl]-ethyl}-dimethylamin, 5-(3-Trimethoxysilyl-propyl)-1,3-bis-(2-methoxyethyl)-hexahydropyrimidin, 5-(3-Ethyldimethoxysilyl-propyl)-1,3-bis-(2-trimethylsilylethyl)-hexahydropyrimidin, 2-[3-(trimethoxysilyl)propyl]-1,3-bis(trimethylsilyl)imidazolidin, 2-(Diethoxyethylsilyl)-1,3-bis(triethylsilyl)imidazolidin, 2-(Triethoxysilyl)-1,4-bis(trimethylsilyl)piperazin, 2-(Dimethoxymethylsilyl)-1,4-bis(trimethylsilyl)piperazin, 5-(Triethoxysilyl)-1,3-bis(tripropylsilyl)hexahydropyrimidin usw.,

[0042] In addition, these include, for example, but are not limited to: [3-(1-hexamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]trimethoxysilane, [2-(1-hexamethyleneimino)ethyl]triethoxysilane, [2-(1-hexamethyleneimino)ethyl]trimethoxysilane, [3-(1-pyrrolidinyl)propyl]triethoxysilane, [3-(1-pyrrolidinyl)propyl]trimethoxysilane, [3-(1-heptamethyleneimino)propyl]triethoxysilane, [3-(1-dodecamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]diethoxymethylsilane, [3-(1-hexamethyleneimino)propyl]diethoxyethylsilane, N-[3-(triethoxysilyl)-propyl]-N,N'-diethyl-N'-trimethylsilyl-ethane-1,2-diamine, N-[2-(trimethoxysilanyl)-ethyl]-N,N',N'-trimethylethane-1,2-diamine, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, etc.

[0043] In addition, these include, but are not limited to, epoxy compounds such as tetraglycidylmetaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane. In addition, these include, but are not limited to, isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, diphenylethane diisocyanate, and 1,3,5-benzene triisocyanate, etc.

[0044] Darüber hinaus gehören dazu bspw., jedoch nicht ausschließlich: 3-(4-Methylpiperazin-1-yl)propyltriethoxysilan, 1-[3-(Diethoxyethylsilyl)propyl]-4-methylpiperazin, 1-[3-(Trimethoxysilyl)propyl]-3-methylimidazolidin, 1-[3-(Diethoxysilyl)propyl]-3-ethylimidazolidin, 1-[3-(Triethoxysilyl)propyl]-3-methylhexahydropyrimidin, 1-[3-(Dimethoxymethylsilyl)propyl]-3-methylhexahydropyrimidin, 3-[3-(Tributoxysilyl)propyl]-1-methyl-1,2,3,4-tetrahydropyrimidin, 3-[3-(Dimethoxymethylsilyl)propyl]-1-ethyl-1,2,3,4-tetrahydropyrimidin, 1-(2-Ethoxyethyl)-3-[3-(trimethoxysilyl)propyl]imidazolidin, (2-{3-[3-(Trimethylsilyl)propyl]tetrahydropyrimidin-yl}ethyl)dimethylamin, 1-[3-(Triethoxysilyl)propyl]-4-(trimethylsilyl)piperazin, 1-[3-(Dimethoxymethylsilyl)propyl]-4-(trimethylsilyl)piperazin, 1-[3-(Tributoxysilyl)propyl]-4-(trimethylsilyl)piperazin, 1-[3-(Diethoxyethylsilyl)propyl]-3-(triethylsilyl)imidazolidin, 2-(Trimethoxysilanyl)-1,3-dimethylimidazolidin,1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)imidazolidine, 1-[3-(dimethoxymethylsilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, 1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, 1-[4-(Triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine etc.,

[0045] Although there is no particular limitation on the coupling agent, from the perspective of reducing the dynamic magnification and the load on production equipment, it is preferable to use a nitrogen atom-containing coupling agent having four or more functional groups in one molecule that react with an active terminal that does not have a halogen.

[0046] When a conjugated diene-based polymer is coupled with a coupling agent, the coupling ratio or degree is preferably 5% or more, more preferably 7% or more, and even more preferably 10% or more, from the perspective of the weight-average molecular weight Mw, Mooney viscosity, and cold flow properties. On the other hand, from the perspective of the degree of modification of the uncoupled portion and the reduction of dynamic magnification, the coupling ratio or degree is preferably 35% or less, more preferably 25% or less, and even more preferably 20% or less. The coupling ratio can be measured by the method specified in the working examples described later. (Modified conjugated diene-based polymer)

[0047] The conjugated diene-based polymer of the present embodiment may be a modified conjugated diene-based polymer. Here, modification refers to the modification of the conjugated diene-based polymer with a nitrogen-containing compound. (Degree of modification)

[0048] In this specification, unless otherwise stated, the term "degree of modification" refers to the mass fraction of the polymer having a nitrogen-containing functional group relative to the total amount of the conjugated diene-based polymer. For example, when a nitrogen-containing modifier is reacted with the terminal end of a polymer, the mass fraction of the polymer having a nitrogen-containing functional group relative to the total amount of the polymer is expressed as the degree of modification by the nitrogen-containing modifier.

[0049] As described below, the nitrogen-containing coupling agent is also contained in the nitrogen-containing modifier. In contrast, a polymer branched with a nitrogen-containing branching agent also has a nitrogen-containing functional group in the resulting copolymer, so this branched polymer is also counted as a polymer having a nitrogen-containing functional group when calculating the degree of modification.

[0050] That is, in the present specification, a polymer having a nitrogen atom-containing functional group is a polymer having a nitrogen atom-containing functional group through a nitrogen atom-containing modifier and a branched polymer having a nitrogen atom-containing functional group through a branching agent, and the total mass fraction of these is the “modification degree”.

[0051] In the conjugated diene-based polymer of the present embodiment, the modification degree measured by the column adsorption GPC method described later (hereinafter simply referred to as "modification degree") is preferably 50% or more, more preferably 60% or more, and even more preferably 65% ​​or more, based on the total amount of the conjugated diene-based copolymer from the perspective of improving the dynamic magnification and dispersibility of the filler such as carbon black. On the other hand, from the perspective of processability and ease of polymerization, it is preferably 98% or less, more preferably 96% or less, and even more preferably 92% or less.

[0052] The degree of modification can be controlled by keeping the amount of modifier added and the polymerization temperature low and suppressing the deactivation of living ends.

[0053] The degree of modification of the conjugated diene-based polymer in the present embodiment can be measured, for example, by chromatography, which can separate the modified component containing the functional group from the unmodified component. The method using this chromatography includes a method (column adsorption GPC method) in which a gel permeation chromatography column is used with polar substances such as silica that adsorb the specific functional group as a filler, and the internal standard of the unadsorbed component is used for comparison and quantification.

[0054] Specifically, the degree of modification can be determined by measuring the adsorption amount on the silica column from the difference between the chromatogram of the sample solution containing the sample and the low molecular weight internal standard polystyrene measured using a polystyrene-based gel column and the chromatogram measured using a silica-based column.

[0055] More specifically, the degree of modification can be measured by the method specified in the working examples.

[0056] The degree of modification of the conjugated diene-based polymer of the present embodiment can be adjusted to the above-mentioned numerical range by controlling the amount of the added modifier and the temperature of the polymerization reaction and suppressing the deactivation of the active end. (modification procedure)

[0057] The modification method includes, although there is no particular limitation, a method using a polymerization initiator containing a nitrogen-containing compound, a method using a nitrogen-containing compound as a polymerization monomer, a method using a nitrogen-containing coupling agent, etc., and further includes a method of reacting a non-coupling nitrogen-containing compound with the end of the reaction, a method of modifying by reacting the double bond of a conjugated diene-based polymer after polymerization with a nitrogen-containing compound, etc.

[0058] The polymerization initiator includes, for example, but is not limited to: reaction products of a nitrogen-containing compound such as dimethylamine, diethylamine, dibutylamine, dipropylamine, diheptylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, didecylamine, ethylpropylamine, ethylbutylamine, ethylbenzylamine, methylphenethylamine, piperidine, hexamethyleneimine, azacyclooctane, 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridine, 3,5-dimethylpiperidine, etc., and of an organic lithium compound such as n-butyllithium, sec-butyllithium, t-butyllithium, n-propyllithium, i-propyllithium, etc.

[0059] In the conjugated diene-based polymer of the present embodiment, the tin content is preferably 50 ppm or less from the perspective of improving dynamic magnification, production stability, and reducing environmental impact. The tin content is more preferably 40 ppm or less, even more preferably 30 ppm or less, even more preferably 20 ppm or less, and particularly preferably 10 ppm or less.

[0060] The tin content in the conjugated diene-based polymer in the present embodiment is the content of tin bonded to the conjugated diene-based polymer. It does not include the tin content in the case where a tin-containing compound is added to the polymer as an additive.

[0061] The tin content in the conjugated diene-based polymer of the present embodiment can be controlled by the type of monomer used in the polymerization, the type of coupling agent and modifier, and the amount of them added.

[0062] Non-coupling nitrogen-containing compounds include, but are not limited to: 1,3-diethyl-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-propyl-2-imidazolidinone, 1-methyl-3-butyl-2-imidazolidinone, 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one, N-methyl-2-pyrrolidone, 1-phenyl-2-pyrrolidone, N-methyl-ε-caprolactam, etc.

[0063] Furthermore, from the perspective of reducing the dynamic magnification, it is preferable that the conjugated diene-based polymer of the present embodiment is a modified conjugated diene-based polymer obtained by reacting a modifier that reacts with an active terminal with at least one >C=O group and at least one substituted amino group in a molecule, or a modified conjugated diene-based polymer obtained by reacting a nitrogen atom-containing coupling agent having four or more functional groups in a molecule that react with an active terminal that does not have a halogen and a modifier that reacts with an active terminal with at least one >C=O group and at least one substituted amino group in a molecule. [Process for producing a conjugated diene-based polymer]

[0064] The conjugated diene-based polymer of the present embodiment can be produced by polymerization, for example, using an organic monolithium compound as a polymerization initiator through a living anionic polymerization reaction. This makes it possible to obtain a conjugated diene-based polymer having an active terminal, and also makes it possible to maintain the linear structure and then appropriately control the branching structure in the branching step using a branching agent described later. Furthermore, there is a tendency to obtain a conjugated diene-based polymer with a high degree of modification by adding a nitrogen atom-containing modifier described later, and in the preparation of a composition containing carbon black, etc.When mixed, there is a tendency to obtain a crosslinked composition with improved dispersion of the filler, such as carbon black, and improved dynamic magnification and durability. This is explained in more detail below.

[0065] The conjugated diene-based polymer of the present embodiment is obtained by conducting a polymerization step in which an aromatic vinyl compound and a conjugated diene compound are polymerized using a specific polymerization initiator. Preferably, a coupling reaction step and / or a modification reaction step may be conducted using the above-described coupling agent and modifier, followed by a hydrogenation step. A branching step may be conducted using a branching agent before the coupling reaction step and the modification step. (polymerization step)

[0066] As the polymerization initiator used in the polymerization step, at least one organic monolithium compound can be used.

[0067] The organic monolithium compound includes, for example, but not exclusively: a low molecular weight compound or an organic monolithium compound of a solubilized oligomer.

[0068] In addition, organic monolithium compounds include, for example, compounds with a carbon-lithium bond, compounds with a nitrogen-lithium bond, and compounds with a tin-lithium bond, in the bonding mode between the organic group and the lithium.

[0069] The amount of the organic monolithium compound used as the polymerization initiator is preferably determined by the structure of the conjugated diene-based polymer and the molecular weight of the conjugated diene-based polymer as a target.

[0070] The amount of monomer used, such as the conjugated diene compound, relative to the amount of polymerization initiator used is related to the degree of polymerization. That is, it tends to be related to the number-average molecular weight and / or the weight-average molecular weight and the peak molecular weight.

[0071] Therefore, in order to increase the molecular weight, it is good to reduce the amount of polymerization initiator used, and in order to decrease the molecular weight, it is good to increase the amount of polymerization initiator used.

[0072] From the perspective that the organic monolithium compound is used as a method for introducing nitrogen atoms into the conjugated diene-based polymer, an alkyllithium compound having a substituted amino group or dialkylaminolithium is preferred.

[0073] In this case, a conjugated diene-based polymer having a nitrogen atom from an amino group at the polymerization initiation end can be obtained.

[0074] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.

[0075] The alkyllithium compound having an amino group that does not have an active hydrogen includes, but is not limited to: 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium and 4-hexamethyleneiminobutyllithium.

[0076] The alkyllithium compound having an amino group with a structure in which the active hydrogen is protected includes, but is not limited to: 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0077] Dialkylaminolithium includes, but is not limited to: lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane and 1-lithio-1,2,3,6-tetrahydropyridine.

[0078] This organic monolithium compound having a substituted amino group can also be used as an organic monolithium compound of a solubilized oligomer by reacting a small amount of polymerizable monomers such as 1,3-butadiene, isoprene, styrene, etc.

[0079] From the perspective of ease of industrial procurement and easy control of the polymerization reaction, the organic monolithium compound is preferably an alkyllithium compound. In this case, a copolymer with an alkyl group at the polymerization initiation end can be obtained.

[0080] Alkyllithium compounds include, but are not limited to: n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium and stilbenelithium.

[0081] From the perspective of easy industrial procurement and easy control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred as the alkyllithium compound.

[0082] This organic monolithium compound can be used individually or in combination with two or more types. It can also be used in combination with another organic metal compound.

[0083] Other organic metal compounds include, but are not limited to: alkaline earth metal compounds, other alkali metal compounds and other organic metal compounds.

[0084] Alkaline earth metal compounds include, but are not limited to, organic magnesium compounds, organic calcium compounds, and organic strontium compounds. They also include compounds of alkoxides, sulfonates, carbonates, and amides of alkaline earth metals.

[0085] Organic magnesium compounds include, but are not limited to, dibutylmagnesium and ethylbutylmagnesium. Other organic metal compounds include, but are not limited to, organic aluminum compounds, etc.

[0086] The polymerization mode in the polymerization step includes, but is not limited to: batch type and continuous polymerization reaction mode.

[0087] In continuous mode, one or more than two connected reactors can be used. Reactors in continuous mode are, for example, tank or tubular reactors with stirrers. In continuous mode, monomers, an inactive solvent, and a polymerization initiator are preferably continuously fed into the reactor. A polymer solution containing the polymer is obtained in the reactor, and the polymer solution is continuously discharged.

[0088] For example, a tank reactor with a stirrer is used as a batch reactor. In batch mode, monomers, an inactive solvent, and a polymerization initiator are preferably fed. If necessary, monomers are added continuously or intermittently during polymerization. A polymer solution containing the polymer is obtained in the reactor. The polymer solution is discharged after the completion of the polymerization.

[0089] In the process for producing the conjugated diene-based polymer of the present embodiment, the continuous mode is preferred in which the polymer is continuously discharged and can be subjected to the next reaction in a short time to obtain a conjugated diene-based polymer having an active terminal with a high content.

[0090] The polymerization step of the conjugated diene-based polymer of the present embodiment is preferably carried out in an inactive solvent. Examples of inactive solvents include, but are not limited to, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Examples of specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, heptane, etc.; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, etc.; and aromatic hydrocarbons such as benzene, toluene, xylene, etc., as well as hydrocarbons consisting of mixtures thereof.

[0091] It is preferable to treat the impurities, such as allenes and acetylenes, with organic metal compounds before subjecting them to the polymerization reaction, since this tends to obtain a conjugated diene-based polymer having an active end in a high concentration and a modified conjugated diene-based polymer with a high degree of modification.

[0092] A polar substance (polar compound) can be added during the polymerization step. This enables the random copolymerization of an aromatic vinyl compound with a conjugated diene compound. The polar substance tends to be used as a vinylating agent, which serves to control the microstructure of the conjugated diene moiety. They also tend to be effective in promoting the polymerization reaction, etc.

[0093] Polar substances include, but are not limited to: ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine and quinucridine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate and sodium amylate; and phosphine compounds such as triphenylphosphine.

[0094] These polar substances can be used individually or in combination with two or more types.

[0095] The amount of the polar substance used is not particularly limited and can be selected depending on the purpose, etc., but 0.01 mol or more and 30 mol or less per 1 mol of the polymerization initiator are preferred.

[0096] Such polar substances (vinylating agents) can be used in the appropriate amount as microstructure regulators for the conjugated diene moiety in the conjugated diene-based polymer, depending on the desired amount of 1,2-vinyl bond. Many polar substances exhibit a randomization effect, which is effective in the copolymerization of the conjugated diene compound and the aromatic vinyl compound, and can be used to control the distribution of the aromatic vinyl compound and as regulators of the amount of styrene blocks.

[0097] As a method for randomizing the conjugated diene compound and the aromatic vinyl compound, for example, as disclosed in JP S59-140211, the copolymerization reaction may be initiated with the total amount of styrene and a portion of 1,3-butadiene, and the remaining 1,3-butadiene may be intermittently added through the copolymerization reaction.

[0098] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the perspective of productivity, it is more preferably 0°C or more, even more preferably 120°C or less, even more preferably 30°C or more and 100°C or less, and particularly preferably 50°C or more and 85°C or less. When it is within this range, there is a tendency that the reaction amount of the modifier with the active terminal after completion of the polymerization can be sufficiently secured. (coupling step, modification step, hydrogenation step)

[0099] The active end of the conjugated diene-based polymer obtained by the above-described polymerization step and, if necessary, the coupling step using the specific coupling agent, can be subjected to a coupling reaction using the above-described coupling agent or a modification reaction using a modifier having a nitrogen atom-containing group. When a nitrogen atom-containing coupling agent is used, the coupling reaction and the modification reaction proceed simultaneously. In addition, a hydrogenation step can be performed in which a hydrogenation reaction is carried out as required. (Step to add an inactivating agent, step to add a neutralizing agent)

[0100] In the process for producing the conjugated diene-based polymer of the present embodiment, an inactivating agent, a neutralizing agent, etc. may be added to the polymer solution as needed.

[0101] Inactivating agents include, but are not limited to: water, alcohols such as methanol, ethanol, isopropanol, etc.

[0102] The neutralizing agent includes, but is not limited to: carboxylic acids such as stearic acid, oleic acid and versatic acid (a mixture of carboxylic acids with 9 to 11 carbon atoms, mainly with 10 carbon atoms and many branches); aqueous solutions of inorganic acids and carbon dioxide. [Soot]

[0103] The crosslinked rubber composition of the present embodiment comprises carbon black as a filler from the perspective of reinforcing effect and processability. There is no particular restriction on the type of carbon black used, but, for example, carbon black / carbon black can be used in various grades such as SAF, ISAF, HAF, MAF, FEF, GPF, SRF, FT, and MT types. These can be used individually or in combination with two or more types.

[0104] The amount of carbon black blended in the crosslinked rubber composition is preferably in the range of 20 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the rubber component comprising at least one kind of conjugated diene-based polymer, and more preferably in the range of 20 to 70 parts by mass, and particularly preferably in the range of 30 to 60 parts by mass. [Silicon dioxide-based inorganic filler]

[0105] The crosslinked rubber composition of the present embodiment may comprise a silica-based inorganic filler from the perspective of low heat generation.

[0106] The content of the silica-based inorganic filler is preferably 1 part by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 55 parts by mass or less, and even more preferably 10 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of the rubber component.

[0107] As the silica-based inorganic filler, any well-known product can be used without limitation, with solid particles containing SiO2 or Si3Al as a structural unit being preferred, and solid particles containing SiO2 or Si3Al as the main component of the structural unit being more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of 50% by mass or more, preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0108] Silica-based inorganic fillers include, but are not limited to: inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite and glass fibers.

[0109] Commercially available silica-based inorganic fillers include, for example, the trade name "UltraSil 7000 GR" manufactured by Evonik Degussa GmbH. In addition, a silica-based inorganic filler with a hydrophobically treated surface and mixtures of a silica-based inorganic filler and another inorganic filler can also be used as the silica-based inorganic filler. Among them, from the perspective of the strength and abrasion resistance of the rubber composition of the present embodiment, silica and glass fiber are preferable as the silica-based inorganic filler, and silica is even more preferable. Examples of silica include dry silica, wet silica, and synthetic silica.

[0110] The amount of silica-based inorganic filler blended in the crosslinked rubber composition is preferably in the range of 20 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the rubber component comprising at least one kind of conjugated diene-based polymer, more preferably in the range of 20 to 70 parts by mass, and particularly preferably in the range of 30 to 60 parts by mass. [Metal oxides, metal hydroxides]

[0111] In addition to the above-described carbon black and silica-based inorganic filler, the crosslinked rubber composition of the present embodiment may also contain metal oxides and metal hydroxides.

[0112] Metal oxides are solid particles with the chemical formula MxOy as the main structural component (M represents a metal atom, and x and y each independently represent an integer from 1 to 6). Examples include aluminum oxide, titanium oxide, magnesium oxide, and zinc oxide. A mixture of metal oxide and another inorganic filler can also be used as a metal oxide.

[0113] Metal hydroxides include, but are not limited to: aluminum hydroxide, magnesium hydroxide and zirconium hydroxide.

[0114] In the crosslinked rubber composition of the present embodiment, it is preferable that the filler is only carbon black from the perspective of dynamic magnification and cost. [Silane coupling agent]

[0115] The crosslinked rubber composition of the present embodiment may contain a silane coupling agent.

[0116] The silane coupling agent has groups that either have an affinity for or bond to the hydrogenated conjugated diene-based polymer, another rubber component, and the silica-based inorganic filler, and functions to enhance the interaction between each of them. A compound containing a sulfur bond moiety, an alkoxysilyl group, and a silanol group moiety in one molecule is generally used as the silane coupling agent.

[0117] The silane coupling agent includes, but is not limited to: 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane [manufactured by Evonik Degussa GmbH: Si363], silane coupling agents containing a mercapto group such as NXT-Z30, NXT-Z45, NXTZ60 and NXT-Silane manufactured by Momentive Performance Materials, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide, Bis(3-triethoxysilylpropyl) trisulfide, bis-[2-(triethoxysilyl)-ethyl] tetrasulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, bis(2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-Mercaptoethyltriethoxysilane, 3-Trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-Triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzenyltetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide, 3-trimethoxysilylpropylmethacrylate monosulfide, Bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, dimethoxymethylsilylpropylbenzothiazolyltetrasulfide, etc.,

[0118] Among them, bis-[3-(triethoxysilyl)-propyl]-disulfide, ethoxy(3-mercaptopropyl)bis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silane [manufactured by Evonik Degussa GmbH: Si363], silane coupling agents containing a mercapto group such as NXT-Z30, NXT-Z45, NXTZ60 and NXT-Silane manufactured by Momentive Performance Materials, and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide are preferred from the perspective of high reinforcement effect.

[0119] The silane coupling agent can be used individually or in combination with two or more types.

[0120] From the perspective of further improving the effect of enhancing the interaction between the rubber component and the silica-based inorganic filler, the content of the silane coupling agent in the crosslinked rubber composition is preferably 2 parts by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 9 parts by mass or less, based on 100 parts by mass of the rubber component. Furthermore, it is 4 parts by mass or more and 15 parts by mass or less, and more preferably 6 parts by mass or more and 12 parts by mass or less, based on 100 parts by mass of the silica-based inorganic filler. [Sulfur]

[0121] The amount of sulfur blended in the crosslinked rubber composition is preferably in the range of 0.1 part by mass or more and 7 parts by mass or less based on 100 parts by mass of the rubber component comprising at least one kind of conjugated diene-based polymer, and is more preferably in the range of 0.5 to 5 parts by mass, and particularly preferably in the range of 1 to 4 parts by mass. (Other mixing materials)

[0122] In the crosslinked rubber composition of the present embodiment, it is also possible to appropriately blend, in addition to the rubber component comprising at least one kind of conjugated diene-based polymer, carbon black and sulfur, a filler other than carbon black, a vulcanization aid, a processing aid, a vulcanization accelerator, a process oil, an antiaging agent, a liquid rubber, a foaming agent, etc., if necessary.

[0123] Fillers other than carbon black include, but are not limited to, silica-based inorganic fillers, calcium carbonate, titanium oxide, aluminum hydroxide, and clay. These can be used individually or in combination with two or more types.

[0124] The vulcanization aid includes zinc oxide (ZnO) and magnesium oxide. These can be used individually or in combination with two or more types. The amount of the mixed vulcanization aid is preferably in the range of 1 to 20 parts by mass based on 100 parts by mass of the rubber component comprising at least one type of conjugated diene-based polymer, and more preferably in the range of 3 to 10 parts by mass.

[0125] The processing aid includes, for example, stearic acid, fatty acid esters, fatty acid amides, and hydrocarbon resins. These can be used individually or in combination of two or more types. The amount of the mixed processing aid is preferably in the range of 1 to 8 parts by mass based on 100 parts by mass of the rubber component comprising at least one type of conjugated diene-based polymer, and more preferably in the range of 1 to 5 parts by mass.

[0126] Examples of vulcanization accelerators include thiazole-, sulfenamide-, thiuram-, aldehyde-ammonia-, aldehyde-amine-, guanidine-, and thiourea-based vulcanization accelerators. These can be used singly or in combination with two or more types. Among them, the sulfenamide-based vulcanization accelerator is preferred from the perspective of crosslinking reactivity. The amount of the vulcanization accelerator blended is preferably in the range of 0.5 to 7 parts by mass based on 100 parts by mass of the rubber component comprising at least one type of conjugated diene-based polymer, and more preferably in the range of 0.5 to 5 parts by mass, and even more preferably in the range of 0.5 to 3 parts by mass.

[0127] Examples of sulfenamide-based vulcanization accelerators include N-oxydiethylene-2-benzothiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, Nt-butyl-2-benzothiazoylsulfenamide, and N,N'-dicyclohexyl-2-benzothiazoylsulfenamide.

[0128] Thiazole-based vulcanization accelerators include, for example, dibenzothiazyl disulfide, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium salt, 2-mercaptobenzothiazole zinc salt, etc.

[0129] Thiuram-based vulcanization accelerators include, for example, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide and tetrabenzylthiuram disulfide.

[0130] It is preferable that the content of the sulfur-based vulcanizing agent as a crosslinking agent is in the range of 0.2 to 3 parts by mass based on the total amount (100 parts by mass) of the rubber component comprising at least one kind of conjugated diene-based polymer of the crosslinked rubber composition of the present embodiment, because good vulcanization crosslinking is achieved.

[0131] The antiaging agent includes, for example, carbamate-based antiaging agents, phenylenediamine-based antiaging agents, phenol-based antiaging agents, diphenylamine-based antiaging agents, quinoline-based antiaging agents, imidazole-based antiaging agents, waxes, etc. These can be used singly or in combination with two or more types. The amount of the antiaging agent blended is preferably in the range of 1 to 10 parts by mass based on 100 parts by mass of the rubber component comprising at least one type of conjugated diene-based polymer, and more preferably in the range of 2 to 5 parts by mass.

[0132] The process oil includes, for example, a naphthenic oil, a paraffinic oil, and an aromatic oil. The amount of the mixed process oil is preferably in the range of 1 to 50 parts by mass, based on 100 parts by mass of the rubber component comprising at least one type of conjugated diene-based polymer, preferably in the range of 3 to 40 parts by mass, and particularly preferably in the range of 5 to 30 parts by mass.

[0133] Liquid rubber can be used as a plasticizer instead of the above process oil or in combination with the process oil. Examples of liquid rubber include, but are not limited to, liquid polybutadiene and liquid styrene-butadiene rubber. The effect of adding liquid rubber is not only to improve the processability of the conjugated diene-based polymer composition blended with the conjugated diene-based polymer and carbon black, but also to shift the glass transition temperature of the conjugated diene-based polymer composition (rubber composition) to a lower temperature, thereby improving the low-temperature properties of the vulcanized product.

[0134] Each of the components shown above can be used individually or in combination with two or more types.

[0135] Regarding the crosslinked rubber composition of the present embodiment, a targeted rubber composition can be obtained by press-vulcanizing the composition (rubber composition) in which the conjugated diene-based polymer obtained in the above-described manner is blended with carbon black, etc., under specific conditions. (Application)

[0136] The crosslinked rubber composition of the present embodiment is not limited to any particular use, but since it has excellent properties such as low dynamic magnification and low performance deterioration upon repeated deformation (improved dynamic magnification and performance stability), it can be suitably used for engine mounts, stabilizer bushings, suspension bushings, etc. used in automobiles, vibration damping rubber, conveyor belts, power transmission belts, and hoses for industrial and other purposes. [Examples of implementation]

[0137] The following concrete embodiments and comparative examples are given to further explain the present embodiment, but the present embodiments are in no way limited by the following embodiments and comparative examples.

[0138] The physical properties of the conjugated diene-based polymer used in the working examples and comparative examples were measured by the methods below. (Styrene content and amount of vinyl bonds of the conjugated diene-based polymer)

[0139] The amount of bound styrene and vinyl bonds was measured by 1H NMR measurement using the conjugated diene-based polymer as a sample.

[0140] The conditions for the 1H NMR measurement are as follows: <messbedingungen> Instrument: JNM-LA400 (manufactured by Jeol Ltd.) Solvent: Deuterated chloroform Sample: Conjugated diene-based polymer Sample concentration: 50 mg / ml Observation frequency: 400 MHz Chemical shift reference: 0.05% mass% TMS (tetramethylsilane) based on deuterated chloroform Pulse delay: 2.904 seconds Number of samples: 64 Pulse width: 45° Measuring temperature: 26°C [Weight average molecular weight Mw]

[0141] A GPC instrument with three connected columns with polystyrene gel as a filler was used to measure the chromatogram, and the weight-average molecular weight Mw was calculated based on the calibration curve using standard polystyrene.

[0142] The specific measurement conditions are as follows: 20 µl of the following measuring fluid was injected into the GPC measuring device for measurement. (Measurement conditions) Device: Trade name "HLC-8320GPC", manufactured by Tosoh Corporation Eluant: tetrahydrofuran (THF) with 5 mmol / l triethylamine Protection column: Trade name “TSKguardcolumn SuperH-H”, manufactured by Tosoh Corporation, Separation column: Trade name "TSKgel SuperH5000", "TSKgel SuperH6000" and "TSKgel SuperH7000" connected in this order, manufactured by Tosoh Corporation Oven temperature: 40°C Flow rate: 0.6 ml / min Detector: RI detector (trade name HLC8020, manufactured by Tosoh Corporation) Measuring liquid: 10 mg sample for measurement, dissolved in 20 ml THF [Clutch ratio or degree]

[0143] When the conjugated diene-based polymer is obtained by a coupling reaction using a coupling agent, the coupling degree (%) is determined by taking the total area of ​​the uncoupled and coupled parts as 100. Degree of coupling (%) = [area of ​​coupled parts / total area] × 100 [Degree of modification of the conjugated diene-based polymer]

[0144] The degree of modification was measured using the column adsorption method-GPC as follows by taking advantage of the property that the modified polymer is adsorbed on the column.

[0145] The adsorption amount to the silica column was measured from the difference between the chromatogram measured with a polystyrene gel-filled column and the chromatogram measured with a silica gel-filled column, and the degree of modification was calculated. (GPC measurement conditions using a polystyrene column)

[0146] The GPC measurement conditions using a polystyrene column were as follows. 20 µL of the following measurement fluid was injected into the GPC instrument for measurement. Device: Trade name "HLC-8320GPC" manufactured by Tosoh Corporation Eluent: THF with 5 mmol / l triethylamine Guard column: Trade name "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation Column: Trade name "TSKgel SuperH5000", "TSKgel SuperH6000" and "TSKgel SuperH7000" connected in this order, manufactured by Tosoh Corporation Oven temperature: 40°C Flow rate: 0.6 ml / min Detector: RI detector (HLC8020 manufactured by Tosoh Corporation) Measurement liquid: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare the sample solution. (GPC measurement conditions using a silica column)

[0147] The GPC measurement conditions using a silica column were as follows. 50 µL of the following measurement fluid was injected into the GPC instrument for measurement. Device: Trade name "HLC-8320GPC" manufactured by Tosoh Corporation Eluent: THF Guard column: Trade name “DIOL 4.6 × 12.5 mm 5 micron” manufactured by GL Sciences Inc. Separation column: Trade name “Zorbax PSM-1000S”, “PSM-300” and “PSM-605” connected in this order, manufactured by Agilent Technologies Japan, Ltd. Oven temperature: 40°C Flow rate: 0.5 ml / min Detector: RI detector (HLC8020, manufactured by Tosoh Corporation) (Method for calculating the degree of modification)

[0148] The total peak area of ​​the chromatogram using the polystyrene column was set as 100, the peak area of ​​the sample as P1, the peak area of ​​the standard polystyrene as P2, the total peak area of ​​the chromatogram using the silica column as 100, the peak area of ​​the sample as P3, and the peak area of ​​the standard polystyrene as P4, and the modification degree (%) was determined using the following formula: Total modification degree (%) = [1 − (P2 × P3) / (P1 × P4)] × 100 (where P1 + P2 = P3 + P4 = 100)

[0149] When a nitrogen-containing coupling agent is used, the coupling portion is also modified. In this case, the degree of modification (%) of the uncoupled portion was determined using the following formula: Degree of modification of the uncoupled part (%) = total degree of modification (%) − nitrogen atom-containing coupling amount (%) [Mooney viscosity: ML]

[0150] The Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132", manufactured by Ueshima Seisakusho Co., Ltd.) according to JIS K6300 (ISO289-1) and ISO289-4. The measurement temperature was 100°C.

[0151] Here, the sample was preheated for one minute, the rotor was rotated at 2 rpm, and the torque was measured after four minutes to determine the Mooney viscosity (ML(1+4)). [Glass transition temperature: Tg]

[0152] The conjugated diene-based polymer was used as a sample, and the measurement was performed according to ISO 22768:2006. 10 mg of the sample was placed in a dedicated aluminum dish, and the instrument used was a DSC7020 differential scanning calorimeter manufactured by Hitachi High-Tech Science Corporation. The temperature was increased from 30°C to 160°C at a rate of 20°C / min and held for 2 minutes. The temperature was then decreased from 160°C to -120°C at a rate of 10°C / min. The DSC curve was recorded while the temperature was increased from -120°C to 100°C at a rate of 10°C / min. The inflection point of the DSC differential curve derived from the glass transition of the conjugated diene-based polymer during the temperature increase from -120°C to 100°C was defined as the glass transition temperature. [Tin content]

[0153] The tin content (unit ppm) in the polymer was measured by elemental analysis using inductively coupled plasma (ICP, manufactured by Shimadzu Corporation, model name: ICPS-8100) and the total content was calculated. [Evaluation of cold flow properties]

[0154] The conjugated diene-based polymer with a stabilizer obtained in the later-described Working Examples and Comparative Examples was used as a sample for measurement. A sample measuring 40 mm × 40 mm × thickness (H0) 50 mm at 25°C was left at 25°C under a load of 1 kg, and the thickness change rate (%) was calculated from the thickness (H60) after 60 minutes of standing using the following formula: Thickness change rate(%)=(H0−H60)×100 / H0

[0155] If the thickness change rate is 60% or less, it is considered satisfactory for practical use and is therefore marked with a circle. If the thickness change rate exceeds 60%, it is marked with a cross, as cold flow during storage is severe and storage and handling properties are poor. [Preparation of conjugated diene-based polymer] (Sample 1) Conjugated diene-based polymer 1<Polymerisation von modifiziertem konjugiertem Dien-basierten Polymer>

[0156] 52500 g of cyclohexane with 150 ppm of added tetrahydrofuran, 6655 g of 1,3-butadiene, 205 g of styrene and 0.030 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0157] The maximum temperature during the polymerization reaction after the start of polymerization was 79°C. Five minutes after reaching the maximum temperature, 2.9 g of 1,3-dimethyl-2-imidazolidinone (0.85 times the molar amount based on n-butyllithium) were added.

[0158] After the reaction was continued for 15 minutes, 9.6 g of methanol (or 0.1 times the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0159] Based on 100 parts of rubber, 0.15 part of Irganox 1520 (manufactured by BASF) and 0.3 part of 1076 (manufactured by ADEKA Corporation) were added as an antiaging agent to the above polymerization solution, and then steam stripping was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 1 (Sample 1). (Sample 2) Conjugated diene-based polymer 2<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0160] 52500 g of cyclohexane with 150 ppm of added tetrahydrofuran, 6860 g of 1,3-butadiene, and 0.030 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0161] The maximum temperature during the polymerization reaction after the start of polymerization was 81°C. Five minutes after reaching the maximum temperature, 2.2 g of 1,3-dimethyl-2-imidazolidinone (0.50 times the molar amount based on n-butyllithium) were added.

[0162] After the reaction was continued for 15 minutes, 9.6 g of methanol (or 0.1 times the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0163] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 2 (Sample 2). (Sample 3) Conjugated diene-based polymer 3<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0164] A 10-liter reactor equipped with a stirrer blade and a jacket was continuously fed with a 15% n-hexane solution of 1,3-butadiene at a rate of 300 ml / min from the bottom, along with 0.17 parts by weight of n-butyllithium per 100 parts by weight of monomer. Polymerization was carried out by mixing and stirring at a speed of 150 rpm and a polymerization temperature of 90°C, and the overflowing living polymer solution was introduced into a static mixer manufactured by Noritake (18 elements). An equivalent amount of methanol was added to the lithium feed before the static mixer.

[0165] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 3 (Sample 3). (Sample 4) Conjugated diene-based polymer 4<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0166] 52500 g of cyclohexane with 150 ppm of added tetrahydrofuran, 6860 g of 1,3-butadiene, and 0.036 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0167] The maximum temperature during the polymerization reaction after the start of polymerization was 83°C. Five minutes after reaching the maximum temperature, 0.92 g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (0.07 times the molar amount based on n-butyllithium) was added as a modifier and allowed to react for 5 minutes. Subsequently, 3.8 g of 1,3-dimethyl-2-imidazolidinone (0.85 times the molar amount based on n-butyllithium) were added.

[0168] After the reaction was continued for 15 minutes, 11.5 g of methanol (or 0.1 times the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0169] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 4 (Sample 4). (Sample 5) Conjugated diene-based polymer 5<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0170] 52500 g of cyclohexane with 150 ppm of added tetrahydrofuran, 6860 g of 1,3-butadiene, and 0.033 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0171] The maximum temperature during the polymerization reaction after the start of polymerization was 79°C. Five minutes after reaching the maximum temperature, 0.60 g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (0.05 times the molar amount based on n-butyllithium) was added as a modifier and allowed to react for 5 minutes. Then, 4.2 g of 1,3-dimethyl-2-imidazolidinone (0.85 times the molar amount based on n-butyllithium) were added.

[0172] After the reaction was continued for 15 minutes, 10.5 g of methanol (or 0.1 times the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0173] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 5 (Sample 5). (Sample 6) Conjugated diene-based polymer 6<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0174] 52500 g of cyclohexane, 6860 g of 1,3-butadiene, and 0.035 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0175] The maximum temperature during the polymerization reaction after the start of polymerization was 79°C. Five minutes after reaching the maximum temperature, 0.27 g of tetramethoxysilane (0.05 times the molar amount based on n-butyllithium) was added as a modifier and allowed to react for 5 minutes. Subsequently, 3.4 g of 1,3-dimethyl-2-imidazolidinone (0.85 times the molar amount based on n-butyllithium) were added.

[0176] After the reaction was continued for 15 minutes, 11.2 g of methanol (or 0.1 times the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0177] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an antiaging agent, and then steam distillation was carried out under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 6 (Sample 6). (Sample 7) Conjugated diene-based polymer 7<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0178] 52500 g of cyclohexane, 6860 g of 1,3-butadiene, and 0.032 mol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0179] The maximum temperature during the polymerization reaction after the start of polymerization was 79°C. Five minutes after reaching the maximum temperature, 0.24 g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (0.03 times the molar amount based on n-butyllithium) was added as a modifier and allowed to react for 5 minutes. Subsequently, 3.1 g of 1,3-dimethyl-2-imidazolidinone (0.85 times the molar amount based on n-butyllithium) were added.

[0180] After the reaction was continued for 15 minutes, 1 g of methanol (or 1 time the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0181] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 7 (Sample 7). (Samples 8 to 10) Conjugated diene-based polymers 8 to 10<Polymerisation von modifizierten konjugierten Dien-basierten Polymeren>

[0182] Except for changing the amounts of n-butyllithium and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane added to the amounts shown in the following table, the same procedure as for Sample 8 was used to obtain the modified conjugated diene-based polymers 8 to 10 (Samples 8 to 10). [Table 1] Unit Sample 8 Sample 9 Sample 10 n-Butyllithium g 2.06 2.20 2.06 1,3-Bis(N,N-diglycidylaminomethyl)cyclohexane g 0.47 0.15 1.22 1,3-Bis(N,N-diglycidylaminomethyl)cyclohexane minor 0.04 0.013 0.08 (Sample 11) Conjugated diene-based polymer 11<Polymerisation von modifiziertem konjugiertem Dien-basiertem Polymer>

[0183] 52500 g of cyclohexane, 6860 g of 1,3-butadiene, and 0.034 millimol of n-butyllithium were placed in an autoclave equipped with a stirrer and the polymerization was started at 40°C.

[0184] The maximum temperature during the polymerization reaction after the start of polymerization was 79°C. Five minutes after reaching the maximum temperature, 0.36 g of tin tetrachloride (0.03 times the molar amount based on n-butyllithium) was added as a modifier and allowed to react for 10 minutes. Then, 1.9 g of 1,3-dimethyl-2-imidazolidinone (0.5 times the molar amount based on n-butyllithium) was added.

[0185] After the reaction was continued for 15 minutes, 1 g of methanol (or 1 time the molar amount based on n-butyllithium) was added as a polymerization terminator to obtain a polymerization solution containing a modified conjugated diene-based rubber.

[0186] Based on 100 parts of rubber, 0.15 part of Irganox 1520 and 0.3 part of 1076 were added to the above polymerization solution as an anti-aging agent, and then steam distillation was performed under conditions of heating to 85 to 98°C using steam. After removing the solvent, the crumb was collected, pressed between stainless steel plates at 30°C for dehydration, and then dried at a roll temperature of 110°C to obtain a modified conjugated diene-based polymer 11 (Sample 11).

[0187] The material properties of Sample 1 (conjugated diene copolymer 1) to Sample 11 are shown in Tables 2 and 3. [Table 2] Conjugated diene-based polymer Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Styrene content (mass%) 2,4 0 0 0 0 0 Vinyl bond amount (mol%) 14 14 11 15 15 16 Weight average molecular weight Mw 39,2 38,3 32,8 32,5 36,9 34,2 Degree of coupling (%) 0 0 0 18,9 16,4 18,4 nitrogen-containing coupling agent - - - ◯ ◯ × Total degree of modification (%) 82.7 49.2 60.4 83.9 80.9 66.4 Degree of modification of the uncoupled part (%) 82.7 49.2 60.4 65 64.5 66.4 ML 50 45 35 45 60 52 Tg (°C) -90.6 -94.6 -95.3 -93.9 -94 -93.2 Tin content (ppm) 0 0 0 0 0 0 Cold flow properties × × × ◯ ◯ ◯ [Table 3] Conjugated diene-based polymer Sample 7 Sample 8 Sample 9 Sample 10 Sample 11 Styrene content (mass%) 0 0 0 0 0 Vinyl bond amount (mol%) 15 15 15 15 15 Weight average molecular weight Mw 39,0 37,0 39,0 30,0 37,0 Degree of coupling (%) 7,0 14,0 5,0 30,0 14,0 nitrogen-containing coupling agent ◯ ◯ ◯ ◯ × Total degree of modification (%) 80 80 80 78 45 Degree of modification of the uncoupled part (%) 73,0 66,0 75,0 48,0 45 ML 55 55 55 55 55 Tg (°C) -94 -94 -94 -94 -94 Tin content (ppm) 0 0 0 0 22 Cold flow properties ◯ ◯ × ◯ ◯

[0188] The materials used in the working examples and comparative examples are as follows: [Rubber components] - Natural rubber (RSS #3) - High-cis polybutadiene (trade name U150, manufactured by UBE Corporation) - Conjugated diene-based polymer (samples 1 to 6) [Added agents] - Filler: Carbon Black (manufactured by Tokai Carbon Co., Ltd. "SEAST KH (N550)") - Filler: Silicon dioxide (manufactured by Evonik Degussa GmbH, trade name "Ultrasil 7000 GR") - Silane coupling agent: (manufactured by Evonik Degussa GmbH, trade name "Si75", bis(triethoxysilylpropyl)disulfide) - Plasticizer: Oil (manufactured by JXTG Nippon Oil & Energy Corporation, PF30) - Vulcanization aid: zinc flower (manufactured by Mitsui Mining & Smelting Co., Ltd., zinc oxide type 2) - Processing aid: Stearic acid (manufactured by Kao Corporation, LUNAC S-90V) - Anti-aging agent: (manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., Nocrac 6C) - Anti-aging agent: (manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., Nocrac MB) - Anti-aging agent: WAX (manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., Sunnoc) - Vulcanization accelerator: (manufactured by Sanshin Chemical Industry Co., Ltd., Sun Cellar NS-G) - Sulfur [Ratio of mixed funds]

[0189] The ratio of each blended agent is shown in Table 4 or Table 6. [Table 4]

[0190] Ratio of each mixed agent when mixing 50 parts by mass of carbon black relative to 100 parts by mass of the rubber component: Added agent Mass part Mass fraction (%) Density (g / cm3) Volume (cm3) Volume fraction (%) Rubber component 100 57,1 0,91 109,9 69,8 CB(N550) 50 28,6 1,8 27,8 17,6 Oil PF30 10 5,7 0,94 10,6 6,8 Spangle 5 2,9 5,6 0,9 0,6 Stearic acid 1 0,6 0,84 1,2 0,8 Nocrac 6C 2 1,1 1,09 1,8 1,2 Nocrac MB 1 0,6 1,43 0,7 0,4 WAX Sunnoc 2 1,1 0,93 2,2 1,4 Sun Cellar NS-G 1,5 0,9 1,27 1,2 0,7 sulfur 2,5 1,4 2 1,3 0,8 sum 175 100 158 100

[0191] The volume fraction of carbon black is 17.6%. [Table 5]

[0192] Ratio of each mixed agent when mixing 30 parts by mass of carbon black relative to 100 parts by mass of the rubber component: Mixed type Mass part Mass fraction (%) Density (g / cm3) Volume (cm3) Volume fraction (%) Rubber component 100 64,5 0,91 109,9 75,1 CB(N550) 30 19,4 1,8 16,7 11,4 Oil PF30 10 6,5 0,94 10,6 7,3 Spangle 5 3,2 5,6 0,9 0,6 Stearic acid 1 0,6 0,84 1,2 0,8 Nocrac 6C 2 1,3 1,09 1,8 1,3 Nocrac MB 1 0,6 1,43 0,7 0,5 WAX Sunnoc 2 1,3 0,93 2,2 1,5 Sun Cellar NS-G 1,5 1,0 1,27 1,2 0,8 sulfur 2,5 1,6 2 1,3 0,9 sum 155 100 146 100

[0193] The volume fraction of carbon black is 11.4%. [Table 6]

[0194] Ratio of each mixed agent when mixing 50 parts by mass of silicon dioxide relative to 100 parts by mass of the rubber component: Mixed type Mass part Mass fraction (%) Density (g / cm3) Volume (cm3) Volume fraction (%) Rubber component 100 58,8 0,91 109,9 72,4 Silicon dioxide (VN3) 50 29,4 1,8 27,8 18,3 Silane coupling agents 5 2,9 1,03 4,9 3,2 Spangle 5 2,9 5,6 0,9 0,6 Stearic acid 1 0,6 0,84 1,2 0,8 Nocrac 6C 2 1,2 1,09 1,8 1,2 Nocrac MB 1 0,6 1,43 0,7 0,5 WAX Sunnoc 2 1,2 0,93 2,2 1,4 Sun Cellar NS-G 1,5 0,9 1,27 1,2 0,8 sulfur 2,5 1,5 2 1,3 0,8 sum 170 100 152 100

[0195] The volume fraction of silicon dioxide is 18.3%. [Example 1]

[0196] In a Labo Plastomill (Model: 10C100) and a Banbury mixer (Model: B600, Capacity: 600 cc) manufactured by Toyo Seiki Seisaku-sho, Ltd., 60 parts by mass of natural rubber (NR) and 40 parts by mass of conjugated diene-based polymer 1 (Sample 1) were masticated for 180 seconds starting at 5°C.

[0197] Next, 50 parts by mass of carbon black (N550), 30 parts by mass of process oil (PF30), 1 part by mass of stearic acid, 5 parts by mass of zinc flower, 2 parts by mass of Nocrac 6C, 1 part by mass of Nocrac MB, and 2 parts by mass of wax (Sunnoc) as an anti-aging agent were added. The mixture was kneaded for another 4 minutes, after which the kneaded rubber material was removed from the mixer. The temperature of the kneaded rubber material was 125°C at the end of the kneading process.

[0198] The kneaded rubber material was mixed and kneaded with 2.5 parts of sulfur and 1.5 parts of vulcanization accelerator (Sun Cellar NS-G) on an open roll (6-inch roll, manufactured by Kansai Roll Co., Ltd.) at 75°C, and then the sheet-shaped rubber composition was removed. There were no particular problems with the processability of this unvulcanized rubber composition.

[0199] The unvulcanized rubber composition was press-cured at 160°C for 20 minutes to prepare a crosslinked rubber composition specimen, and the hardness, tensile properties, compression set, static spring constant, dynamic spring constant, dynamic magnification, and storage modulus G' were measured.

[0200] The results are shown in Table 7. [Comparison example 1]

[0201] Except for changing the conjugated diene-based polymer 1 (Sample 1) to high-cis polybutadiene U150, a sample of the crosslinked rubber composition was prepared in the same manner as in Working Example 1, and various measurements were carried out.

[0202] The results are shown in Table 7. (Examples 2 to 5, 8 to 10, Comparative Examples 2, 4 to 5)

[0203] Except for changing the type of the conjugated diene-based polymer to that shown in Table 4, a sample of the crosslinked rubber composition was prepared in the same manner as in Working Example 1, and various measurements were performed. The results are shown in Table 7. (Examples 6 and 7, Comparative Example 3)

[0204] Except for changing the type of the conjugated diene-based polymer and the amount of carbon black to 30 parts by mass per 100 parts by mass of the rubber component, a sample of the crosslinked rubber composition was prepared in the same manner as in Working Example 1, and various measurements were performed. The results are shown in Table 8. [Comparison examples 6 to 8]

[0205] Except for changing carbon black as the filler to silica, a sample of the crosslinked rubber composition was prepared in the same manner as in Example 1, and various measurements were performed. The results are shown in Table 9.

[0206] The thus obtained crosslinked rubber compositions of the working examples and comparative examples were evaluated by various measurements according to the following criteria. [Storage modulus G', Payne effect ΔG', storage modulus repeated measurement]

[0207] Using a viscoelasticity testing machine "Main Unit MCR102 + Unit EVU20", manufactured by Anton Paar GmbH, the storage modulus G' (0.1% strain), measured in torsion mode at a temperature of 50°C and a frequency of 10 Hz at a strain of 0.1%, and the storage modulus G' (10% strain), measured at a strain of 10%, were calculated as the Payne effect. ΔG' = G' (0.1% strain) - G' (10% strain) was calculated as the difference between these values, ΔG' = G' (0.1% strain) - G' (10% strain). For the same volume fraction of carbon black, the lower the Payne effect value, the better the dispersion of the carbon black.

[0208] From the difference of the storage moduli G' (0.1% deformation) and G' (10% deformation) in two measurements of the storage moduli in the first measurement, the change rate for each deformation of 0.1% and 10% was calculated. Difference of G' (0.1% deformation) between two measurements = G' at the first measurement − G' at the second measurement Difference of G' (10% deformation) between two measurements = G' at the first measurement − G' at the second measurement Rate of change of G'=(Difference of G'(0.1% deformation) between the two measurements / G' at the first measurement)×100 Rate of change of G'=(Difference of G'(10% deformation) between the two measurements / G' at the first measurement)×100

[0209] The smaller the rate of change, the smaller the change in performance and the better the result. [Tensile properties, reduction rate of breaking strength, reduction rate of breaking elongation, hardness]

[0210] Each unvulcanized rubber composition was compression molded at 160°C for 20 minutes and punched out using a JIS No. 5 barbell to prepare a 2 mm thick tensile test piece. Using this tensile test piece, the 100% modulus (M100), ultimate strength (Tb), ultimate elongation (Eb), and hardness (Hs: JIS A) were measured according to JIS K6251.

[0211] The 2 mm thick tensile test piece, which was prepared by punching using the JIS No. 5 dumbbell, was heated in an environment of 100°C for 24 hours, and then the ultimate strength (Tb) and elongation (Eb) were measured.

[0212] The reduction rate of ultimate strength (Tb) and ultimate elongation (Eb) after heating were calculated compared to the ultimate strength (Tb) and ultimate elongation (Eb) before heating. The lower the reduction rate, the better the result. [Compression set]

[0213] According to JIS K6262, the compression set was measured after 24 hours of heating in an environment of 100°C. The lower the compression set, the better the result. [Static spring constant, dynamic spring constant, dynamic magnification]

[0214] According to JIS K6385, the static spring constant and dynamic spring constant of the crosslinked rubber composition were measured and the dynamic magnification (dynamic spring constant / static spring constant) was calculated.

[0215] The measuring device used was ACUMEN3, manufactured by MTS. (Static spring constant: Ks)

[0216] Using each unvulcanized rubber composition, a test piece was prepared by pressing it under vulcanization conditions of 120°C for 20 minutes to produce a crosslinked rubber composition with a columnar shape (50 mm in diameter, 25 mm in height). Then, a pair of disc-shaped metal fittings (60 mm in diameter, 6 mm in thickness) were bonded to the top and bottom surfaces of this crosslinked rubber composition with an adhesive. Next, the above-mentioned test piece was compressed by 7 mm in the axial direction of the column, and the static spring constant (Ks) was calculated by reading the load at deflections of 1.5 mm and 3.5 mm from the second load-deflection line. (Dynamic spring constant: Kd100)

[0217] The above test piece was compressed by 2.5 mm in the axial direction of the column, and a constant harmonic displacement vibration with an amplitude of 0.05 mm was applied from the bottom at a frequency of 100 Hz, centered at the 2.5 mm compression position. The dynamic load was recorded with a load cell on the top, and the dynamic spring constant (Kd100) was calculated and measured. (Dynamic magnification: Kd100 / Ks)

[0218] The dynamic magnification was calculated as the dynamic spring constant (Kd100) / static spring constant (Ks). The lower the dynamic magnification, the better the vibration damping properties.

[0219] From the results in Table 7 above, it is clear that the crosslinked rubber compositions of the working examples containing 50 parts of carbon black (17.6% by volume) had lower dynamic magnification and better vibration damping rubber material properties than the crosslinked rubber compositions of the comparative examples, and had better properties in terms of the reduction rate of breaking strength and elongation at break after heating, and compression set. [Table 8] Examples of implementation Comparison example 6 7 3 Mixing quantity of rubber component (parts by mass) Natural rubber 60 60 60 BR with high cis contentU150 40 Rubber from Sample 1 40 Rubber from sample 3 40 Mixing quantity of the admixed agents per 100 parts by mass of rubber (parts by mass) Carbon Black N550 30 30 30 Öl PF30 10 10 10 Stearic acid LUNAC 1 1 1 Vulcanization aids Spangle 5 5 5 Anti-aging agents Nocrac 6C 2 2 2 Nocrac MB 1 1 1 WAX (Sunnoc) 2 2 2 sulfur sulfur 2,5 2,5 2,5 Vulcanization accelerator Sun Cellar NS-G 1,5 1,5 1,5 Physical properties ΔG' MPa 0,325 0,165 0,823 G' (0.1% deformation) at the first measurement MPa 1,888 1,473 2,703 G' (0.1% deformation) in the second measurement MPa 1,799 1,400 2,424 Difference between the two measurements 0,089 0,073 0,279 Rate of change of G' (0.1% deformation) at 4,714 4,956 10,322 G' (10% deformation) at the first measurement MPa 1,568 1,309 1,881 G' (10% deformation) in the second measurement MPa 1,504 1,250 1,704 Difference between the two measurements 0,064 0,058 0,177 Rate of change of G' (10% deformation) at 4,050 4,455 9,410 hardness Shore A 55,0 54,0 57,0 Breaking strength MPa 21,0 20,7 25,0 Elongation at break % 424 449,7 472 100% Mo MPa 2,3 2,2 2,8 300% Mo MPa 11,4 9,9 12,1 Reduction rate of fracture strength % -18,7 -20,7 -28,2 Reduction rate of elongation at break % -22,2 -24,8 -27,7 Compression set % 42,5 43,4 45,1 Static spring constant N / mm 268 249 254 Dynamic spring constant N / mm 605 545 613 Dynamic magnification - 2,26 2,19 2,41

[0220] From the results in Table 8 above, it is clear that the crosslinked rubber compositions of the working examples containing 30 parts of carbon black (11.4% by volume) had lower dynamic magnification and better vibration damping rubber material properties than the crosslinked rubber composition of the comparative example, and had better properties in terms of the reduction rate of breaking strength and elongation at break after heating, and compression set. [Table 9] Comparison examples 6 7 8 Mixing amount of rubber (part by mass) Natural rubber 60 60 60 BR with high cis content Rubber from Sample 1 40 40 Rubber from Sample 2 Rubber from sample 3 Rubber from sample 4 Rubber from sample 5 Rubber from sample 6 Rubber from sample 7 40 Rubber from sample 8 Rubber from sample 9 Rubber from sample 10 Rubber from sample 11 Mixing quantity of the added agents per 100 parts by mass of rubber (parts by mass) Carbon Black 0 0 0 Silicon dioxide 50 50 30 Silane coupling agents 5 5 5 Öl 0 0 0 Stearic acid 1 1 1 Vulcanization aids 5 5 5 Anti-aging agents 2 2 2 1 1 1 2 2 2 sulfur 2,5 2,5 2,5 Vulcanization accelerator 1,5 1,5 1,5 Physical properties ΔG' 4,808 4,1297 2,259 G' (0.1% deformation) at the first measurement 10,740 9,987 5,231 G' (0.1% deformation) in the second measurement 9,321 8,987 4,876 Difference between the two measurements 1,419 0,9997 0,355 Rate of change of G' (0.1% deformation) with two measurements (%) 13,212 10,010 6,786 G' (10% deformation) at the first measurement 5,932 5,857 2,972 G' (10% deformation) in the second measurement 5,231 5,354 2,776 Difference between the two measurements 0,701 0,503 0,196 Rate of change of G' (10% deformation) with two measurements (%) 11,817 8,588 6,595 hardness 65 65 65 Breaking strength 22 22 22 Elongation at break 380 380 380 100%Mo 3,4 3,4 3,4 300%Mo 16 16 16 Reduction rate of breaking strength -10,0 -10,0 -10,0 Reduction rate of elongation at break -20,0 -20,0 -20,0 Compression set 44 44 44 Static spring constant 320 320 320 Dynamic spring constant 1150 1150 1150 Dynamic magnification 3,59 3,59 3,59

[0221] From the results in Table 9 above, it is apparent that the crosslinked rubber compositions of Comparative Examples comprising 50 parts of silica (18.3% by volume) had higher dynamic magnification and inferior vibration damping rubber material properties, as well as inferior properties in terms of the reduction rate of breaking strength and elongation at break after heating, and compression set, compared with the crosslinked rubber compositions of Working Examples. INDUSTRIAL APPLICABILITY

[0222] The crosslinked rubber composition of the present invention has industrial applicability as a molding material for engine mounts, stabilizer bushings, suspension bushings, etc. used in automobiles, vibration-damping rubber, conveyor belts, power transmission belts, hoses for industrial and other purposes, vibration-damping dampers for computer hard disks, vibration-damping dampers for general household appliances such as washing machines, and vibration control devices (vibration damping) such as vibration control walls and vibration control dampers (vibration isolators), and seismic isolation devices in the field of architecture and housing. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2018-35253

[0002] JP 2007-70582 A

[0002] JP H05-202102

[0003] JP 2023-519535

[0003] JP S59-140211

[0097] < / messbedingungen>

Claims

[1] A crosslinked rubber composition comprising a rubber component comprising at least one conjugated diene-based polymer, carbon black and sulfur, wherein - the storage modulus after deformation ΔG' = G' (0.1% deformation) - G' (10% deformation) is 3.0 MPa or less, - when the storage modulus is measured twice after deformation, the difference in the storage modulus G' (0.1% deformation) between the two measurements is 0.4 MPa or less and the difference in the storage modulus G' (10% deformation) between the two measurements is 0.2 MPa or less, and - when the storage modulus is measured twice after deformation, the rate of change of the storage modulus G' between the two measurements at 0.1% deformation and between the two measurements at 10% deformation is 6.0% or less, using the following calculation formulas: Difference of G'(0.1% deformation) between the two measurements = G' at the first measurement − G' at the second measurement Difference of G'(10% deformation) between the two measurements = G' at the first measurement − G' at the second measurement Rate of change of G'=(Difference of G'(0.1% deformation) between the two measurements / G' at the first measurement)×100 Rate of change of G'=(Difference of G'(10% strain) between the two measurements / G' at the first measurement)×100. [2] The crosslinked rubber composition according to claim 1, wherein the volume fraction of carbon black in the crosslinked rubber composition is 7 to 30 vol%. [3] The crosslinked rubber composition according to claim 1 or 2, wherein the glass transition temperature of the conjugated diene-based polymer is -110°C to -80°C. [4] The crosslinked rubber composition according to claim 1 or 2, wherein the 1,2-vinyl bond amount in the conjugated diene monomer unit of the conjugated diene-based polymer is 10 mol% or more and 25 mol% or less. [5] The crosslinked rubber composition according to claim 1 or 2, wherein the aromatic vinyl monomer unit content of the conjugated diene-based polymer is 0 mass% or more and 7 mass% or less. [6] The crosslinked rubber composition according to claim 1 or 2, wherein the conjugated diene-based polymer is a modified conjugated diene-based polymer obtained by reacting a modifier reacting with an active terminal with at least one >C=O group and at least one substituted amino group in one molecule, or a modified conjugated diene-based polymer obtained by reacting a nitrogen atom-containing coupling agent having four or more functional groups in one molecule which react with an active terminal not having a halogen and a modifier reacting with an active terminal with at least one >C=O group and at least one substituted amino group in one molecule. [7] The crosslinked rubber composition according to claim 1 or 2, wherein the degree of modification of the modified conjugated diene-based polymer obtained by reacting the modifier with at least one >C=O group and at least one substituted amino group in a molecule which react with the active terminal, measured by column adsorption GPC method, is 50% or more and 99% or less. [8] The crosslinked rubber composition according to claim 6, wherein the coupling degree of the modified conjugated diene-based polymer obtained by a nitrogen atom-containing coupling agent having four or more functional groups in one molecule which react with the active terminal having no halogen is 7% or more and 25% or less. [9] The crosslinked rubber composition according to claim 6, wherein the coupling degree of the modified conjugated diene-based polymer obtained by a nitrogen atom-containing coupling agent having four or more functional groups in one molecule which react with the active terminal having no halogen is 7% or more and 15% or less. [10] The crosslinked rubber composition according to claim 1 or 2, wherein the tin content of the conjugated diene-based polymer is 20 ppm or less. [11] The crosslinked rubber composition according to claim 1 or 2, wherein the filler in the crosslinked rubber composition is exclusively carbon black. [12] A vibration damping rubber comprising the crosslinked rubber composition according to claim 1 or 2. [13] Power transmission belt and conveyor belt comprising the crosslinked rubber composition according to claim 1 or 2.