Polymer composition and method for producing same, formulation, crosslinked product, and tire

Abstract

The polymer composition contains a modified conjugated diene polymer and an acid component and includes a nonionic surfactant and / or an extender oil as optional components. The acid component is an acid or a metal salt thereof or both. The content proportion of the acid component is 0.1-20 mass parts per 100 mass parts of the modified conjugated diene polymer. The total amount of the modified conjugated diene polymer, the acid component, the nonionic surfactant, and the extender oil is 95 mass% or more of the whole composition. The modified conjugated diene polymer has a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups.

Description

Polymer composition, its manufacturing method, blend, crosslinked product, and tire

[0001] [Cross-reference to related applications] This application claims priority to Japanese Patent Application No. 2023-170352, filed on September 29, 2023, the entire contents of which are incorporated herein by reference. The present disclosure relates to a polymer composition, a method for producing the same, a compound, a crosslinked product thereof, and a tire.

[0002] Conjugated diene polymers obtained by polymerization using conjugated diene compounds have various good properties such as heat resistance, abrasion resistance, mechanical strength, moldability, etc., and are therefore widely used in various industrial products such as pneumatic tires, anti-vibration rubber, hoses, etc. For example, it is known that compounds used in the production of treads, sidewalls, etc. of pneumatic tires contain reinforcing agents such as carbon black and silica in addition to the conjugated diene polymer in order to improve the durability and abrasion resistance of the products.

[0003] As conjugated diene polymers, various modified conjugated diene polymers have been proposed in which functional groups that interact with silica have been introduced into the chain ends or main chains of the conjugated diene polymer chain in order to obtain tires with superior fuel economy.Modified conjugated diene polymers have better compatibility with reinforcing fillers such as carbon black and silica than unmodified conjugated diene polymers, and therefore can suppress heat generation and improve fuel economy in tire applications.

[0004] In addition, in order to further improve tire properties such as fuel economy, it has been proposed to incorporate additives into a solution containing a conjugated diene polymer obtained by polymerization reaction and then remove the solvent (see Patent Documents 1 and 2). Patent Document 1 discloses that rolling resistance, tensile strength, etc. are improved by incorporating a dispersant such as bis-(2-hydroxyethylisotridecyloxypropylamine) into a solution containing a modified conjugated diene polymer. Patent Document 2 also discloses that quality stability and silica dispersibility are improved by producing a rubber bale by adding a nonionic surfactant such as di(polyoxyethylene)stearylamine to a solution containing a modified or unmodified conjugated diene polymer.

[0005] JP-T-2017-508841 A JP-A-2019-182996 A

[0006] When a polymer composition is produced by blending an additive into a solution containing a conjugated diene polymer and then removing the solvent as in Patent Document 1 and Patent Document 2, the polymer composition is prone to change in performance when stored for a long period of time, and has poor stability over time. For polymer compositions used in the production of rubber products, there is a need for a technology that can obtain crosslinked products that have high tensile strength and excellent fuel economy while suppressing changes in physical properties of the polymer composition due to long-term storage.

[0007] The present disclosure has been made in view of the above-mentioned problems, and a main object of the present disclosure is to provide a polymer composition that has excellent stability over time while obtaining a crosslinked product that exhibits high tensile strength and good fuel economy performance.

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by a polymer composition containing a modified conjugated diene-based polymer having a specific structure and a specific additive. Specifically, the present disclosure provides the following polymer composition, a production method thereof, a compound, a crosslinked product, and a tire.

[0009] [1] A polymer composition comprising a modified conjugated diene-based polymer and an acid component, and optionally containing one or both of a nonionic surfactant and an extender oil, wherein the acid component is an acid or a metal salt thereof, or both, the content of the acid component is 0.1 to 20 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, the content of the nonionic surfactant is 0 to 5 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, and the content of the extender oil is 0 to 50 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, the total amount of the modified conjugated diene-based polymer, the acid component, the nonionic surfactant, and the extender oil is 95% by mass or more of the total composition, and the modified conjugated diene-based polymer has a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups.

[0010] [2] A compound obtained by compounding the polymer composition of [1] above with a filler. [3] A crosslinked body obtained by crosslinking the compound of [2] above. [4] A tire having a tread, a sidewall, or both, wherein the tread, the sidewall, or both are made using the compound of [2] above.

[0011] [5] A method for producing a polymer composition, comprising: a step of mixing a modified conjugated diene polymer and an acid component in an organic solvent in a ratio of 0.1 to 20 parts by mass of the acid component per 100 parts by mass of the modified conjugated diene polymer to obtain a mixture; and a step of removing the solvent from the mixture, wherein the acid component is an acid or a metal salt thereof, or both, and the modified conjugated diene polymer has a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups.

[0012] According to the present disclosure, a polymer composition having excellent stability over time can be obtained while obtaining a crosslinked product exhibiting high tensile strength and good fuel economy performance. Furthermore, by using the polymer composition, a crosslinked product having high tensile strength and excellent fuel economy performance can be obtained.

[0013] Matters related to the implementation of the present disclosure will be described in detail below. Note that this specification is not limited to the embodiments described below, and should be understood to include various modifications that are implemented within the scope of the present invention.

[0014] Herein, in this specification, a numerical range described using "to" means that the numerical values ​​described before and after "to" are included as the lower and upper limits. The term "(meth)acrylic" is a concept that includes both "acrylic" and "methacrylic". The term "(meth)acrylate" is a concept that includes both "acrylate" and "methacrylate".

[0015] <Polymer Composition> The polymer composition of the present disclosure (hereinafter also referred to as "the composition") contains a modified conjugated diene-based polymer (component (A)) and an acid component (component (B)). The composition may further contain, as optional components, one or both of a nonionic surfactant (component (C)) and an extender oil (component (D)). Each component contained in the composition and optional components included therein will be described below.

[0016] <Component (A): Modified Conjugated Diene Polymer> The modified conjugated diene polymer contained in the present composition (hereinafter also referred to as "modified conjugated diene polymer (A)") is a modified product having a monomer unit derived from a conjugated diene compound.

[0017] The modified conjugated diene polymer (A) has a partial structure derived from a compound having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups (hereinafter also referred to as "compound (M)"). The inclusion of such a modified conjugated diene polymer in the present composition can enhance the dispersibility of the filler (particularly silica) when the composition is blended with a filler. In terms of a high effect of improving the dispersibility of the filler, the modified conjugated diene polymer (A) preferably has a partial structure derived from compound (M) and multiple conjugated diene polymer chains bonded to the partial structure derived from compound (M). Compound (M) will be described in detail in the section below titled "Modification Step."

[0018] In this specification, the term "hydrocarbyloxysilyl group" refers to a monovalent or divalent group in which 1 to 3 hydrocarbyloxy groups are bonded to a silicon atom. １ ) ３－ｗ (R ２ ) ｗ " or ">Si(OR １ ) ２－ｙ (R ２ ) ｙ ” (However, R １ and R ２ are each independently a hydrocarbyl group, w is an integer of 0 to 2, and y is 0 or 1. For example, "-Si(OR １ ) ３" in one molecule and having a nitrogen-containing group is a "compound having a nitrogen-containing group and two hydrocarbyloxysilyl groups." The expression "having two or more hydrocarbyloxysilyl groups" does not indicate the number of hydrocarbyloxy groups bonded to the silicon atom.

[0019] The modified conjugated diene polymer (A) can be produced by a method including the following polymerization step and modification step: Polymerization step: A step of polymerizing a monomer containing a conjugated diene compound in the presence of a polymerization initiator to obtain a conjugated diene polymer having an active end; Modification step: A step of reacting a conjugated diene polymer having an active end with a compound (M) to obtain a modified conjugated diene polymer (A).

[0020] Hereinafter, the molecular structure of the modified conjugated diene polymer (A) will be described together with the method for producing the modified conjugated diene polymer (A).

[0021] <Polymerization Step> (Conjugated Diene Compound) Examples of conjugated diene compounds include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, and 2-chloro-1,3-butadiene. The conjugated diene compound is preferably one or more of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene, with 1,3-butadiene being particularly preferred due to its high effect of improving processability and reduced hysteresis loss in a well-balanced manner. The conjugated diene compounds may be used alone or in combination of two or more.

[0022] The conjugated diene polymer may be a homopolymer using a conjugated diene compound, but from the viewpoint of increasing the strength of the rubber, it is preferably a copolymer having a structural unit derived from a conjugated diene compound and a structural unit derived from an aromatic vinyl compound. Examples of aromatic vinyl compounds include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene (e.g., 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene). Of these, styrene or α-methylstyrene is preferred as the aromatic vinyl compound.

[0023] When the conjugated diene polymer produced in the polymerization step is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the conjugated diene polymer is preferably a copolymer having structural units derived from 1,3-butadiene and structural units derived from styrene, in view of its high living property in anionic polymerization. When the conjugated diene polymer is a copolymer, the copolymer is preferably a random copolymer of a conjugated diene compound and an aromatic vinyl compound. The random copolymer may further have a block portion composed of a conjugated diene compound or another aromatic vinyl compound.

[0024] The proportion of the aromatic vinyl compound used is preferably 3 to 55 mass %, more preferably 5 to 50 mass %, based on the total amount of monomers used in polymerization, from the viewpoint of achieving a good balance between low hysteresis loss properties (low fuel consumption performance) and wet skid resistance, and good abrasion resistance, of the crosslinked product obtained using the present composition. The content of the structural unit derived from the aromatic vinyl compound in the polymer is １ This is a value measured by H-NMR.

[0025] In the polymerization, compounds other than conjugated diene compounds and aromatic vinyl compounds (hereinafter also referred to as "other monomers") may be used as monomers. Examples of other monomers include acrylonitrile, methyl (meth)acrylate, and ethyl (meth)acrylate. When other monomers are used, the proportion of the other monomers is preferably 5% by mass or less, and more preferably 3% by mass or less, of the total amount of monomers used in the polymerization.

[0026] The polymerization method is particularly preferably a solution polymerization method. The polymerization method may be either a batch method or a continuous method. From the viewpoint of polymer productivity, a continuous method is preferred. When using the solution polymerization method, a specific example of the polymerization method is a method in which a monomer is polymerized in an organic solvent in the presence of a polymerization initiator and, if necessary, a vinyl group content adjuster (randomizer).

[0027] Specific examples of the polymerization method include a method in which an organic solvent, a polymerization initiator, and a monomer are added to a reaction vessel all at once, and a method in which an organic solvent, a polymerization initiator, and a monomer are added to a reaction vessel continuously or intermittently multiple times to polymerize. From the viewpoints of improving the processability of the polymer composition, enhancing the dispersibility of the filler (particularly silica), and obtaining a crosslinked product having excellent tensile properties, it is preferable to produce the modified conjugated diene polymer (A) using a method in which an organic solvent, a polymerization initiator, and a monomer are added to a reaction vessel continuously or intermittently multiple times to polymerize.

[0028] As the polymerization initiator, at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds can be preferably used. Specific examples thereof include alkyllithium, 1,4-dilithiobutane, phenyllithium, stilbenelithium, naphthyllithium, 1,3-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,3-phenylenebis(3-methyl-1-phenylpentylidene)dilithium, naphthylsodium, naphthylpotassium, di-n-butylmagnesium, di-n-hexylmagnesium, ethoxypotassium, and calcium stearate. Specific examples of alkyllithium include methyllithium, ethyllithium, n-propyllithium, n-butyllithium, sec-butyllithium, and t-butyllithium. The polymerization initiator is preferably a lithium compound. The proportion of polymerization initiator used during polymerization (the total amount when two or more types are used) is preferably 0.2 to 20 mmol per 100 g of monomer used in polymerization.

[0029] The polymerization reaction may be carried out in the presence of a compound (hereinafter also referred to as a "metal amide compound") obtained by mixing at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds with an initiation terminal-modifying agent. By polymerizing a monomer in the presence of a metal amide compound, a functional group derived from the initiation terminal-modifying agent can be introduced into the polymerization initiation terminal of the conjugated diene polymer.

[0030] As the initiating terminal modifying agent, nitrogen-containing compounds such as secondary amine compounds can be preferably used. Specific examples of the initiating terminal modifying agent include chain amines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, di-(2-ethylhexyl)amine, and diallylamine; and cyclic amines such as piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine, and 1,3-ditrimethylsilyl-1,3,5-triazinane.

[0031] When polymerizing a monomer in the presence of a compound obtained by mixing an alkali metal compound or alkaline earth metal compound with an initiating terminal modifier, at least one of the alkali metal compound and alkaline earth metal compound may be mixed with the initiating terminal modifier in advance, and the mixture may be added to the polymerization system to carry out polymerization. Alternatively, at least one of the alkali metal compound and alkaline earth metal compound and the initiating terminal modifier may be added to the polymerization system separately or simultaneously, and the two may be mixed in the polymerization system to carry out polymerization. Either of these cases is included in the embodiment of "polymerizing a monomer in the presence of a compound obtained by mixing at least one selected from the group consisting of alkali metal compounds and alkaline earth metal compounds with the initiating terminal modifier."

[0032] The amount of initiating end-modifier used is appropriately set depending on the type of alkali metal compound or alkaline earth metal compound. For example, when metallic lithium is used, from the viewpoint of obtaining a modified conjugated diene-based polymer having a well-balanced improvement in processability and fuel economy, the amount of initiating end-modifier used is preferably in the range of 0.1 to 1.8 mol, more preferably in the range of 0.2 to 1.0 mol, per mol of the total metallic lithium used in the polymerization. As the initiating end-modifier, one type may be used alone, or two or more types may be used in combination.

[0033] In addition, a nitrogen-containing alkali metal compound can also be used as a polymerization initiator in the polymerization reaction. Examples of the nitrogen-containing alkali metal compound include compounds represented by the following formula (1). (In formula (1), R ８ is a nitrogen-containing group. １ is a hydrocarbylene group obtained by polymerization of a conjugated diene compound or an aromatic vinyl compound. １ is an alkali metal. n is an integer from 1 to 10.

[0034] In the above formula (1), R ８ The nitrogen-containing group is the group "-(CH ２ ) ｎ Y is preferably a monovalent group that is bonded to "-" via a nitrogen atom and does not contain active hydrogen, and more preferably a tertiary amino group. １ Regarding the conjugated diene compound and aromatic vinyl compound, the compounds exemplified as the monomers to be used in polymerization can be used. １ is preferably a hydrocarbylene group obtained by polymerization of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene or styrene, and more preferably a hydrocarbylene group obtained by polymerization of isoprene. １ The degree of polymerization of M is preferably 2 to 10, more preferably 2 to 4. １ Examples of the ions include lithium, sodium, and potassium, and lithium is preferred.

[0035] An example of the compound represented by the above formula (1) is ((2E,6E)-11-(dimethylamino)-3,7-dimethylundeca-2,6-dien-1-yl)lithium.

[0036] A partial structure derived from a nitrogen-containing compound can be introduced into the polymerization initiation terminal by either a method of polymerizing a monomer in the presence of a compound obtained by mixing an alkali metal compound or alkaline earth metal compound with an initiation terminal modifier, or a method of polymerizing a monomer in the presence of a nitrogen-containing alkali metal compound.

[0037] Vinyl group content adjusters (randomizers) are used for the purpose of adjusting the vinyl group content, which represents the content of vinyl bonds in a polymer. Examples of randomizers include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, and tetramethylethylenediamine. Randomizers can be used alone or in combination of two or more.

[0038] The organic solvent used in the polymerization may be any organic solvent that is inert to the reaction. Examples of such organic solvents include linear or cyclic aliphatic hydrocarbons and aromatic hydrocarbons. The organic solvent used in the polymerization is preferably a hydrocarbon having 3 to 8 carbon atoms, and specific examples thereof include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, and cyclohexene. These organic solvents may be used alone or in combination of two or more.

[0039] When solution polymerization is performed, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. The temperature of the polymerization reaction is preferably −20° C. to 150° C., and more preferably 0 to 120° C. Furthermore, the polymerization reaction is preferably carried out under a pressure sufficient to maintain the monomers substantially in a liquid phase. Such a polymerization reaction can produce a conjugated diene polymer having an active end (more specifically, an alkali metal active end or an alkaline earth metal active end). In this specification, the term “active end” refers to a portion (more specifically, a metal end) present at the end of the molecular chain other than the structure derived from the monomer having a carbon-carbon double bond.

[0040] The 1,2-vinyl group content (hereinafter also referred to as "vinyl group content") of the conjugated diene polymer having an active terminal is preferably 15% by mass or more, and more preferably 20% by mass or more. When the vinyl group content is 15% by mass or more, good wet grip properties tend to be ensured. Furthermore, the vinyl group content is preferably 70% by mass or less. When the vinyl group content is 70% by mass or less, good fuel economy performance tends to be ensured. From this viewpoint, the vinyl group content is more preferably 60% by mass or less, and even more preferably 50% by mass or less. In this specification, the "vinyl group content" is a value indicating the content ratio of structural units having 1,2-bonds to all structural units of butadiene in the conjugated diene polymer, １ This is a value measured by H-NMR.

[0041] <Modification Step> The modified conjugated diene polymer (A) is preferably a polymer obtained by reacting the active terminals of the conjugated diene polymer obtained in the polymerization step with a compound (M) as a terminal modifier. By reacting a conjugated diene polymer having active terminals with the compound (M), a polymer chain containing a monomer unit derived from the conjugated diene compound is bonded to the compound (M) at the reaction site of the compound (M), thereby obtaining a modified conjugated diene polymer (A) having multiple polymer chains in one molecule. This allows the crosslinked body obtained using this composition to have excellent low heat buildup.

[0042] The conjugated diene polymer having an active end to be reacted with the compound (M) may have a modified or unmodified polymerization initiation end. By reacting a conjugated diene polymer having an active end, the polymerization initiation end of which has been modified with a nitrogen-containing compound, with the compound (M), a modified conjugated diene polymer having a partial structure derived from the nitrogen-containing compound at at least some of the ends of a plurality of conjugated diene polymer chains can be obtained.

[0043] The compound (M) may have one or more nitrogen-containing groups and two or more hydrocarbyloxysilyl groups per molecule. The nitrogen-containing groups are preferably one or more selected from the group consisting of protected primary amino groups, protected secondary amino groups, tertiary amino groups, imino groups, and imidazolyl groups. These groups allow for relatively easy introduction of functional groups that contribute significantly to improving the dispersibility of fillers (especially silica) into the polymer.

[0044] The protected primary amino group includes a group in which two hydrogen atoms bonded to the nitrogen atom in the primary amino group are each substituted with a monovalent protecting group. The protected secondary amino group includes a group in which one hydrogen atom bonded to the nitrogen atom is substituted with a monovalent protecting group, as well as the amino group in an azasilolidine group. Note that the following formula (2) (In formula (2), R ａ is a hydrocarbyloxy group, and R ｂis a hydrocarbyl group or a hydrocarbyloxy group. "*" represents a bond.) ａ ) (R ｂ )-) is a group that reacts with the active terminal of a conjugated diene polymer and is also a protecting group that protects the secondary amino group. The partial structure represented by the above formula (2) has one hydrocarbyloxy group and one nitrogen-containing group (i.e., a protected secondary amino group). Here, in this specification, the term "protecting group" refers to a group that converts the nitrogen-containing group into a functional group that is inactive against the active polymerization terminal. Examples of monovalent protecting groups include a trihydroalkylsilyl group.

[0045] A preferred specific example of the compound (M) is at least one selected from the group consisting of a compound represented by the following formula (3), a compound represented by the following formula (4), and a compound represented by the following formula (5): (In formula (3), A ３ has a hydrocarbyloxysilyl group, optionally has a nitrogen atom, has no active hydrogen, and R ２２ is a monovalent functional group bonded to R via nitrogen or silicon. ２２ is a single bond or a hydrocarbylene group, and R ２３ and R ２４ are each independently a hydrocarbyl group, and R ２５ is a hydrocarbylene group, and t is 0 or 1. However, when t is 0, multiple R ２４ are the same or different.) (In formula (4), R ３１ is an alkanediyl group having 1 to 20 carbon atoms, and R ３２ and R ３３ are each independently a hydrocarbyl group having 1 to 20 carbon atoms, and A １ is the group "*-C(R ３５ )=N-" or the group "*-N=C(R ３５ ) -" (However, R ３５ is a hydrogen atom or a hydrocarbyl group, and "*" is R ３４ represents a bond bonded to the atom. ３４is an m-valent hydrocarbon group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms and having at least one atom selected from the group consisting of nitrogen, oxygen, and sulfur, and having no active hydrogen. n is an integer of 1 to 3, and m is an integer of 2 to 10. R ３１ ~R ３３ and A １ For each symbol, when the same symbol is present multiple times in the formula, the groups represented by the symbols may be the same or different. Multiple n's in the formula may be the same or different. (In formula (5), R ４２ , R ４３ and R ４５ are each independently an alkanediyl group having 1 to 12 carbon atoms, and R ４０ , R ４１ , R ４８ and R ４９ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. ２ represents a nitrogen-containing heterocyclic group or the following formula (a-2): (In formula (a-2), R ４６ and R ４７ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. a is an integer of 1 to 3. When the same symbol exists multiple times in the formula, the groups represented by those symbols are the same or different from each other. "*" represents a bond.) is a group represented by. c and d are each independently an integer of 1 to 3, and b is an integer of 1 to 10. When the same symbol exists multiple times in the formula, the groups represented by those symbols are the same or different from each other.)

[0046] In the above formula (3), R ２３ , R ２４ The hydrocarbyl group represented by R is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. ２２ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms. ２５ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms. ２５is preferably a hydrocarbylene group having 2 to 4 carbon atoms, more preferably a linear hydrocarbylene group having 2 to 4 carbon atoms, and even more preferably a 1,3-propanediyl group.

[0047] A ３ Specific examples of the group include groups represented by the following formula (a3-1) or (a3-2). (In formula (a3-1) and formula (a3-2), R ２６ and R ２７ are each independently a hydrocarbyl group. y is an integer from 0 to 2. z is 0 or 1. When y is 2, multiple R ２６ When y is 0 or 1, multiple R ２７ When z is 0, multiple R ２７ are the same or different. ２８ is a hydrocarbylene group. "*" is R ２２ represents a bond with .)

[0048] In the above formula (a3-1) or (a3-2), R ２６ or R ２７ Preferred examples of the hydrocarbyl group represented by R ２３ , R ２４ The same groups as those given as preferred examples of R ２８ Preferred examples of the hydrocarbylene group represented by R ２５ The same groups as those given as preferred examples of the above can be mentioned.

[0049] In the above formula (4), R ３１ Examples of the hydrocarbylene group include an alkanediyl group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, and an arylene group having 6 to 12 carbon atoms. ３２ and R ３３ Examples of the hydrocarbyl group include an alkyl group having 1 to 20 carbon atoms, an allyl group, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

[0050] R ３４ The m-valent hydrocarbon group is a group obtained by removing m hydrogen atoms from a hydrocarbon.３４ The m-valent hydrocarbon group is preferably a group (m-valent aromatic ring group) obtained by removing m hydrogen atoms from the ring portion of an aromatic hydrocarbon. Specific examples of aromatic hydrocarbons include single rings or condensed rings such as benzene rings, naphthalene rings, and anthracene rings, and structures in which two or more of these rings are bonded by a single bond.

[0051] R ３４ is an m-valent group having 1 to 20 carbon atoms, having at least one atom selected from the group consisting of nitrogen, oxygen, and sulfur, and having no active hydrogen, specific examples thereof include an m-valent heterocyclic group, an m-valent group having a tertiary amine structure, etc. The heterocyclic group is preferably a conjugated system, and examples thereof include a single ring or condensed ring such as pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, furan, thiophene, etc., or a group in which m hydrogen atoms have been removed from the ring portion of a structure in which a plurality of these rings are linked together.

[0052] From the viewpoint of improving the processability of the polymer composition, m is preferably 2 to 6. n is preferably 2 or 3, and more preferably 3, from the viewpoint of enhancing the effect of improving silica dispersibility.

[0053] In the above formula (5) and formula (a-2), R ４５ , R ４２ and R ４３ The alkanediyl group in R is preferably linear. ４０ , R ４１ , R ４６ ~R ４９ Examples of the hydrocarbyl group include an alkyl group having 1 to 20 carbon atoms, an allyl group, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. ２ The nitrogen-containing heterocyclic group represented by the formula (I) is preferably a group derived from a conjugated heterocycle, and examples thereof include groups in which one hydrogen atom has been removed from a nitrogen-containing heterocycle such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, or benzimidazole.

[0054] a, c, and d are preferably 2 or 3, more preferably 3, in that the effect of improving silica dispersibility can be further enhanced. b is preferably 1 to 5, more preferably 1 to 3.

[0055] Specific examples of the terminal-modifying agent include compounds represented by the above formula (3), such as 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1,2-azasilolidine, 1,3-bis(2,2-dimethoxy-1,2-azasilolidine-1-yl)propane, and compounds in which the alkyl groups and alkanediyl groups in these compounds are replaced with alkyl groups and alkanediyl groups having 1 to 6 carbon atoms, respectively. For example, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1,2-azasilolidine is a compound having one nitrogen-containing group and two hydroxycarbyloxysilyl groups.

[0056] Examples of the compound represented by formula (4) include compounds represented by the following formulae (m-1-1) to (m-1-8): and compounds in which the alkyl group and alkanediyl group in the compounds are replaced with alkyl groups having 1 to 6 carbon atoms and alkanediyl groups having 1 to 6 carbon atoms, respectively.

[0057] Examples of the compound represented by formula (5) include tris(2-triethoxysilylethyl)amine, tris(3-triethoxysilylpropyl)amine, tris(5-triethoxysilylpentyl)amine, N,N,N',N'-tetra(2-triethoxysilylethyl)-1,2-diaminoethane, N,N,N',N'-tetra(3-triethoxysilylpropyl)-1,3-diaminopropane, N-(3-(1H-imidazol-1-yl)propyl)-N,N-bis(3-(trimethoxysilyl))propyl)propanamine, and compounds in which the alkyl groups and alkanediyl groups in these compounds are replaced with alkyl groups and alkanediyl groups having 1 to 6 carbon atoms, respectively. As the terminal modifying agent, one of these may be used alone, or two or more may be used in combination.

[0058] The reaction between the polymerization active terminal and the terminal modifier is preferably carried out as a solution reaction. This solution reaction may be carried out using a solution containing unreacted monomers after the polymerization reaction has been completed, or may be carried out after isolating the conjugated diene polymer having polymerization active terminals contained in the solution and dissolving it in a suitable solvent such as cyclohexane. The reaction may be carried out either batchwise or continuously. The method for adding the terminal modifier is not particularly limited, and examples thereof include a method of adding it all at once, a method of adding it in portions, and a method of adding it continuously.

[0059] The amount of the terminal modifier used in the reaction may be appropriately determined depending on the type of compound used in the reaction. The amount of the terminal modifier used is preferably 0.1 mol equivalent or more, more preferably 0.3 mol equivalent or more, relative to the metal atoms involved in the polymerization reaction of the polymerization initiator. By using an amount of the terminal modifier used in the reaction of 0.1 mol equivalent or more, the modification reaction can be sufficiently promoted, and the dispersibility of the filler can be suitably improved. Furthermore, the amount of the terminal modifier used is preferably 1.5 mol equivalent or less, more preferably 1.2 mol equivalent or less, relative to the metal atoms involved in the polymerization reaction of the polymerization initiator.

[0060] The reaction temperature is usually the same as the polymerization reaction temperature, and is preferably -20°C to 150°C, and more preferably 0 to 120°C. If the reaction temperature is too low, the viscosity of the modified conjugated diene polymer tends to increase. On the other hand, if the reaction temperature is too high, the active polymerization terminals are likely to be deactivated. The reaction time is preferably 1 minute to 5 hours, and more preferably 2 minutes to 1 hour.

[0061] When producing the modified conjugated diene polymer (A), a treatment of reacting the polymerization active terminal with a coupling agent may be carried out for the purpose of increasing the Mooney viscosity and cold flow characteristics of the polymer. The reaction using the coupling agent may be carried out before or after the reaction of the polymerization active terminal with the terminal-modifying agent, or may be carried out simultaneously with the reaction of the polymerization active terminal with the terminal-modifying agent. Specific examples of the coupling agent include 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, N,N,N',N'-tetramethylphthalamide, tetrachlorosilicon, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, and tin tetrachloro. Alternatively, before the reaction of the polymerization active terminal with the terminal-modifying agent, an aromatic vinyl compound having a hydrocarbyloxysilyl group bonded to an aromatic ring (also referred to as a "specific branching agent") may be reacted, and then one or both of a conjugated diene compound and an aromatic vinyl compound (excluding the specific branching agent) may be added to further promote the polymerization reaction, and then the terminal-modifying agent may be added.

[0062] When a compound having a protecting group (such as a trimethylsilyl group) is used as the terminal modifier, a modified conjugated diene polymer having protecting groups derived from the terminal modifier may be partially or completely hydrogen-substituted to obtain a polymer, which may be used as the modified conjugated diene polymer in the subsequent steps. Furthermore, when a protecting group-containing compound is used as the terminal modifier, the modified conjugated diene polymer modified with the terminal modifier may be further reacted with an onium salt generator. In this case, a polymer having an onium salt structure at the polymer terminal can be obtained as the modified conjugated diene polymer. Having an onium salt structure in the modified conjugated diene polymer is preferred in that it can improve the shape retention of a crosslinked body obtained using the polymer composition.

[0063] The weight average molecular weight (Mw) of the modified conjugated diene polymer (A) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 1.0×10 ５ or more. Mw is 1.0 × 10 ５When the Mw of the modified conjugated diene polymer (A) is 1.2×10 or more, the crosslinked product tends to have sufficiently high shape stability, tensile strength, and abrasion resistance. ５ More preferably, 1.5×10 ５ The Mw of the modified conjugated diene polymer (A) is preferably 3.0 × 10 ６ Mw is 3.0 × 10 or less. ６ If the Mw of the modified conjugated diene polymer (A) is more than 2.5×10, the processability of the polymer composition tends to be reduced. ６ More preferably, 2.0 × 10 ６ The weight average molecular weight (Mw) of the modified conjugated diene polymer (A) referred to here is the value (total weight average molecular weight) determined from all peaks of a GPC curve measured by GPC.

[0064] The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the modified conjugated diene polymer (A) in terms of polystyrene, measured by GPC, is preferably 1.05 to 4.00. When Mw / Mn is 1.05 or more, good processability can be maintained during the production of a crosslinked body, and good filler dispersibility, rolling resistance (fuel economy), and tensile properties tend to be achieved. The Mw / Mn of the modified conjugated diene polymer (A) is more preferably 1.10 or more, and even more preferably 1.20 or more. When Mw / Mn of the modified conjugated diene polymer (A) is 4.00 or less, good fuel economy and good reinforcing filler dispersibility tend to be achieved during the crosslinked body. The Mw / Mn of the modified conjugated diene polymer (A) is more preferably 3.50 or less, and even more preferably 3.00 or less.

[0065] <Component (B): Acid Component> The acid component (hereinafter also referred to as "acid component (B)") contained in the present composition is an acid or a metal salt thereof. The present composition may contain only an acid as the acid component (B), only a metal salt of an acid, or both an acid and a metal salt thereof.

[0066] In the acid component (B), the acid may be an inorganic acid (e.g., boric acid, hydrochloric acid, nitric acid, phosphoric acid, etc.) or an organic acid. The metal element contained in the metal salt of the acid is not particularly limited. Examples of the metal element constituting the metal salt of the acid include alkali metal elements, alkaline earth metal elements, Group 4 elements, Group 13 elements, Group 14 elements, and Group 15 elements. The metal element constituting the metal salt of the acid is preferably one or more of sodium, calcium, titanium, tin, zirconium, bismuth, and aluminum, more preferably sodium or tin, and even more preferably tin.

[0067] The acid constituting the acid component (B) is preferably an organic acid, since the acid component (B) can be retained in the modified conjugated diene polymer (A) to thereby obtain a polymer composition in which deterioration in performance over time is sufficiently suppressed. Furthermore, the acid component (B) preferably contains at least one selected from the group consisting of organic acids and organic acid salts.

[0068] Specific examples of organic acids include carboxylic acids, carboxylic acid anhydrides, organic (phosphorous) acids, organic sulfonic acids, organic sulfinic acids, thioacids, etc. Further specific examples of these include carboxylic acids such as formic acid, acetic acid, maleic acid, propionic acid, isobutyric acid, 2-methylbutyric acid, octylic acid, 2-methylpentanoic acid, 2-ethylhexanoic acid, cyclohexanecarboxylic acid, oleic acid, lauric acid, palmitic acid, stearic acid, isostearic acid, methoxyacetic acid, 2-chloropropionic acid, 3-chloropropionic acid, α-bromopropionic acid, acrylic acid, methacrylic acid, vinylacetic acid, crotonic acid, sorbic acid, glyoxylic acid, pyruvic acid, levulinic acid, phenylacetic acid, benzoic acid, thioglycolic acid, β-mercaptopropionic acid, Examples of the alkyl esters include nitrobenzoic acid, salicylic acid, lactic acid, dimethylolpropionic acid, dimethylolbutanoic acid, gluconic acid, isoleucine, alanine, glycine, β-alanine, threonine, serine, isoserine, tyrosine, aminobenzoic acid, tryptophan, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, methylsuccinic acid, sebacic acid, dodecanedioic acid, fumaric acid, itaconic acid, citraconic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, trimellitic acid, pyromellitic acid, tartaric acid, citric acid, malic acid, glutamic acid, aspartic acid, and cystine.

[0069] Examples of carboxylic acid anhydrides include isobutyric anhydride, itaconic anhydride, succinic anhydride, acetic anhydride, citraconic anhydride, propionic anhydride, maleic anhydride, butyric anhydride, phthalic anhydride, etc. Examples of organic (or phosphorous) acids include methyl dimethylphosphinate, ethyl diphenylphosphinate, dimethyl methylphosphonate, diphenyl phenylphosphonate, trimethyl phosphate, triphenyl phosphate, methyldiphenyl phosphate, and ethylmethylphenyl phosphate.

[0070] Examples of organic sulfonic acids include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, etc. Examples of organic sulfinic acids include methanesulfinic acid, ethanesulfinic acid, p-toluenesulfinic acid, trifluoromethanesulfinic acid, etc. Examples of thioacids include dithioacetic acid, etc.

[0071] Examples of organic acid salts include sodium compounds, calcium compounds, titanium compounds, tin compounds, zirconium compounds, bismuth compounds, and aluminum compounds of the organic acids exemplified above. Specific examples include sodium 2-ethylhexanoate, calcium bis(2-ethylhexanoate), titanium bis(oleate)bis(2-ethylhexanoate), titanium tetrakis(2-ethylhexanoate), titanium tetrakis(laurate), titanium tetrakis(stearate), tin bis(2-ethylhexanoate), zirconium bis(2-ethylhexanoate), bismuth tris(2-ethylhexanoate), aluminum tris(2-ethylhexanoate), and aluminum tris(stearate).

[0072] The acidity of the acid constituting the acid component (B) is not particularly limited. The pH of the acid constituting the acid component (B) at 20°C is, for example, 1 to 6. In terms of the effect of improving the temporal stability of the modified conjugated diene-based polymer (A), the acid constituting the acid component (B) preferably has a pH of 2 to 5, more preferably 2 to 4.5, at 20°C. In this specification, the pH of the acid component (B) is a value measured using a mixed solution of 1.0 g of the acid and 1.0 L of water for an organic acid, and a value measured using a 1 mol / L aqueous solution for an inorganic acid. For a metal salt of an acid, the value is represented by the pH of the acid constituting the metal salt.

[0073] The acid component (B) preferably has high solubility in a good solvent for the modified conjugated diene polymer (A). Specifically, an acid or a metal salt thereof having a solubility in cyclohexane at 25°C of 1.0 g / L or more can be preferably used as the acid component (B). By using such an acid or a metal salt thereof as the acid component (B), the dispersibility of the acid component (B) in the modified conjugated diene polymer (A) can be increased, and the stability of the modified conjugated diene polymer (A) over time due to the acid component (B) can be further improved. The solubility of the acid or a metal salt thereof in cyclohexane can be evaluated by preparing a mixture with cyclohexane so that the acid or the metal salt thereof has a desired concentration, and observing the state of insoluble acid or the metal salt thereof and phase separation in the mixture.

[0074] The content of the acid component (B) is 0.1 to 20 parts by mass relative to 100 parts by mass of the modified conjugated diene polymer (A). If the content of the acid component (B) is less than 0.1 parts by mass, the polymer composition will have insufficient stability over time, making it impossible to obtain a crosslinked product exhibiting good performance. Furthermore, if the content of the acid component (B) is more than 20 parts by mass, the acid component (B) will cause a decrease in the performance of the modified conjugated diene polymer (A). From these viewpoints, the content of the acid component (B) is preferably 0.15 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the modified conjugated diene polymer (A). Furthermore, the content of the acid component (B) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the modified conjugated diene polymer (A). The acid component (B) may be used singly or in combination of two or more types.

[0075] <Component (C): Nonionic Surfactant> The present composition may further contain a nonionic surfactant. By further containing a nonionic surfactant in the present composition, the strength and fuel economy of the crosslinked body obtained using the present composition can be further improved while the temporal stability of the polymer composition is improved.

[0076] The nonionic surfactant to be blended in the composition is not particularly limited, and examples of the nonionic surfactant include a compound represented by the following formula (6), a compound represented by the following formula (7), and a compound represented by the following formula (8). (In formulas (6) to (8), R ５１ is a hydrocarbyl group having 10 to 18 carbon atoms, and R ５２ and R ５３ are each independently a hydrocarbyl group or -(R ５６ O) ｒ -H. ５６ is an ethylene group or a propylene group, and r is an integer of 1 or more. When r is 2 or more, a plurality of R ５６ are the same or different. ５１ represents a single bond, an oxygen atom, or -NR ５５ - and R ５４ is X ５１ is a single bond, and X ５１ is an oxygen atom or -NR ５５ - is a hydrocarbylene group. ５５ represents a hydrogen atom, a hydrocarbyl group, or -(R ５６ O) ｒ -H.)

[0077] In the above formulas (6) to (8), R ５１ is preferably a saturated or unsaturated linear hydrocarbyl group, more preferably a linear alkyl or alkenyl group. ５４ is a hydrocarbylene group, R ５４ is preferably a saturated or unsaturated linear hydrocarbylene group, more preferably a linear alkanediyl group or alkenediyl group.

[0078] Specific examples of these compounds include compounds represented by the above formula (6), such as polyoxyethylene alkylamines, polyoxypropylene polyoxyethylene alkylamines, polyoxypropylene alkylamines, polyoxyethylene-alkylpropylene-diamines, polyoxypropylene-alkylpropylene-diamines, 1,1'-(dodecylimino)bis(2-propanol), 2,2'-(dodecylimino)bisethanol, and 2,2'-(hexadecylimino)bisethanol.

[0079] Specific examples of the compound represented by the above formula (7) include glycerin monostearate and glycerin monooleate.

[0080] Specific examples of the compound represented by the above formula (8) include polyoxyethylene lauric acid monoethanolamide, polyoxypropylene coconut oil fatty acid monoethanolamide, polyoxypropylene myristate monoethanolamide, polyoxypropylene coconut oil fatty acid monoisopropanolamide, and the like.

[0081] Other examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene distyrenated phenyl ethers, polyoxyethylene polyoxypropylene glycol or fatty acid esters thereof, fatty acid esters of pentaerythritol, fatty acid esters of polyoxyethylene sorbitan, polyoxyethylene ethers of glycerin esters, polyethylene glycol fatty acid esters, sorbitan esters, and glucosides.

[0082] The nonionic surfactants include those having a propylene glycol chain (-(R ５０ -O) ｊ -, but R ５０ is a propylene group, and j is an integer of 1 or more). ５０ Examples of the alkyl group include a 1,2-propylene group and a 1,3-propylene group.

[0083] As the nonionic surfactant, a compound having an HLB of 9.0 or less can be preferably used. Here, HLB stands for hydrophilic-lipophilic balance, and is a value that changes depending on the balance between hydrophilic groups and lipophilic groups in the molecule. The larger the HLB value, the higher the hydrophilicity. In this specification, the HLB value is a value calculated using the calculation formula proposed by Griffin (Griffin method; 20 x (sum of formula weights of hydrophilic moieties (e.g., alkyl ether moieties) in the surfactant / molecular weight of the surfactant)). When the nonionic surfactant is composed of two or more compounds, it is preferable that the value calculated by the weighted average of the HLB values ​​of each component is 9.0 or less.

[0084] The HLB value of the nonionic surfactant is preferably 8.0 or less, more preferably 7.0 or less, even more preferably 6.7 or less, and particularly preferably 6.5 or less, in order to retain and stabilize the nonionic surfactant in the rubber. The HLB value of the nonionic surfactant is 0 or more. Setting the HLB value of the nonionic surfactant within the above range is advantageous in that a high-performance modified conjugated diene polymer (A) can be obtained using an aqueous solvent when isolating the modified conjugated diene polymer (A) in the subsequent solvent removal step.

[0085] The content of the nonionic surfactant in the composition is 0 to 5 parts by mass per 100 parts by mass of the modified conjugated diene polymer (A). If the content of the nonionic surfactant exceeds 5 parts by mass, the strength and fuel economy of the crosslinked body obtained using the composition tend to decrease, and the effect of improving the temporal stability of the polymer composition by adding the acid component (B) tends to be insufficient. From these viewpoints, the content of the nonionic surfactant is more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the modified conjugated diene polymer (A). Furthermore, when adding a nonionic surfactant to improve the strength and fuel economy of the crosslinked body, the content of the nonionic surfactant is preferably 0.1 parts by mass or more per 100 parts by mass of the modified conjugated diene polymer (A). As the nonionic surfactant, one type may be used alone, or two or more types may be used in combination.

[0086] <Component (D): Extender Oil> The composition may contain a process oil commonly used to extend elastomers as an oil (extender oil) for oil extension. Preferred process oils include various oils known in the art, such as aromatic oils, paraffinic oils, naphthenic oils, vegetable oils such as soybean oil and sunflower oil, as well as oils with a low content of polycyclic aromatic compounds (low PCA oils), such as mild extraction solvate (MES), treated distillate aromatic extract (TDAE), special residual aromatic extract (SRAE), and heavy naphthenic oil. Examples of commercially available MES, TDAE, and SRAE include Catenex SNR (heavy paraffin obtained by dewaxing distillate oil with a solvent) manufactured by Shell as an MES, Vivatec 500 manufactured by H&R Wasag AG as a TDAE, and NC140 manufactured by Japan Energy Corp. as an SRAE.

[0087] When an extender oil is blended into the composition, the content of the extender oil in the composition is preferably 0.05 to 50 parts by mass per 100 parts by mass of the modified conjugated diene polymer (A) contained in the composition, from the viewpoint of improving processability while suppressing a decrease in rolling resistance and strength. The content of the extender oil is more preferably 0.1 parts by mass or more, and even more preferably 0.2 parts by mass or more, per 100 parts by mass of the modified conjugated diene polymer (A). Furthermore, the content of the extender oil is more preferably 47 parts by mass or less, and even more preferably 45 parts by mass or less, per 100 parts by mass of the modified conjugated diene polymer (A).

[0088] The present composition contains a modified conjugated diene polymer (A) and an acid component (B), and also contains a nonionic surfactant and an extender oil as optional components. Note that, since the nonionic surfactant is an optional component, the content of the nonionic surfactant in the present composition may be 0% by mass. Similarly, since the extender oil is an optional component, the content of the extender oil in the present composition may be 0% by mass.

[0089] In the present composition, the total amount of the modified conjugated diene polymer (A), acid component (B), nonionic surfactant, and extender oil is 95% by mass or more of the total composition. In the present composition, the total amount of the modified conjugated diene polymer (A), acid component (B), nonionic surfactant, and extender oil is preferably 97% by mass or more, more preferably 98% by mass or more, of the total amount of the composition. One embodiment of the present composition is a solid polymer composition from which the solvent has been removed. The present composition may be in the form of solid particles (crumbs), or may be a rubber bale obtained by compression molding the crumbs into a desired shape (e.g., a rectangular parallelepiped).

[0090] <<Method for Producing Polymer Composition>> The present composition is preferably produced by a method including the following mixing step and desolvation step. Mixing step: a step of mixing a modified conjugated diene polymer (A) and an acid component (B) in an organic solvent in a ratio of 0.1 to 20 parts by mass of the acid component (B) per 100 parts by mass of the modified conjugated diene polymer (A) to obtain a mixture. Desolvation step: a step of removing the organic solvent from the mixture obtained in the mixing step (hereinafter also referred to as "mixture SC") Each step will be described in detail below.

[0091] <Mixing Step> In the mixing step, the modified conjugated diene polymer (A) and the acid component (B) are mixed in an organic solvent. Examples of the organic solvent include the organic solvents exemplified as solvents that can be used for polymerizing the monomers. As the organic solvent, at least one selected from the group consisting of chain aliphatic hydrocarbons, cyclic aliphatic hydrocarbons, and aromatic hydrocarbons can be preferably used.

[0092] From the viewpoint of increasing the dispersibility of the acid component (B) in the present composition and sufficiently improving the stability over time of the present composition, it is preferable that in the mixing step, a polymer solution in which the modified conjugated diene polymer (A) is dissolved in an organic solvent (hereinafter also referred to as "polymer solution SA") is mixed with the acid component (B).

[0093] As the polymer solution SA, a reaction solution containing the modified conjugated diene polymer (A) obtained by the process including the polymerization process and the modification process described above may be used as it is, or a solution prepared by isolating the modified conjugated diene polymer (A) contained in the reaction solution and dissolving it in an appropriate solvent may be used. From an industrial viewpoint, it is preferable to use the reaction solution containing the modified conjugated diene polymer (A) obtained by the above-mentioned modification process as it is, since this reduces the number of processes and increases productivity. Note that the details of the polymerization process and the modification process are the same as those described above.

[0094] The content of the modified conjugated diene polymer (A) in the polymer solution SA is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total amount of the polymer solution SA. The content of the modified conjugated diene polymer (A) in the polymer solution SA is preferably 90% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less. By adjusting the content of the modified conjugated diene polymer (A) in the polymer solution SA to 1% by mass or more, a sufficient production amount can be ensured during the production of the present composition. By adjusting the content to 90% by mass or less, the acid component (B) can be uniformly dispersed in the polymer solution SA, thereby improving the quality and stability of the resulting polymer composition.

[0095] The manner in which the modified conjugated diene polymer (A) and the acid component (B) are mixed is not particularly limited. For example, when the acid component (B) is added to a polymer solution SA containing the modified conjugated diene polymer (A), the acid component (B) may be added to the polymer solution SA all at once, in portions, or continuously. Furthermore, when the acid component (B) is added to the polymer solution SA, the acid component (B) may be added as a stock solution, or the stock solution of the acid component (B) may be diluted with an organic solvent capable of dissolving the acid component (B) and then added. After the acid component (B) is added to the polymer solution SA, it is preferable to perform a treatment such as stirring to uniformly disperse the acid component (B) in the polymer solution SA. The temperature when mixing the polymer solution SA and the acid component (B) is the same as the temperature of the polymerization reaction, and is preferably −20° C. to 150° C., more preferably 0 to 120° C., and even more preferably 20 to 100° C.

[0096] When an extender oil is blended into the present composition, the method for adding the extender oil is not particularly limited. For example, an extender oil may be added to a polymer solution containing the modified conjugated diene-based polymer (A) after polymerization, and then removed in a subsequent solvent removal step to form an oil-extended rubber. In this case, the extender oil may be added before adding the acid component (B) to the polymer solution, or may be added after adding the acid component (B) to the polymer solution. The extender oil may also be added directly during kneading to obtain a rubber compound (compounded rubber).

[0097] Furthermore, when a nonionic surfactant is incorporated into the present composition, it is preferable to mix the modified conjugated diene polymer (A), the acid component (B), and the nonionic surfactant in an organic solvent and then remove the solvent in a subsequent solvent removal step. By mixing the nonionic surfactant with the modified conjugated diene polymer (A) before the solvent removal step, the nonionic surfactant can be retained in the modified conjugated diene polymer (A). In this case, the nonionic surfactant may be added before the acid component (B) is added to the polymer solution, or may be added after the acid component (B) is added to the polymer solution.

[0098] When the modified conjugated diene polymer (A) and the acid component (B) are mixed, it is preferable that the amount of the acid component (B) be 0.1 to 20 parts by mass per 100 parts by mass of the modified conjugated diene polymer (A). If the content of the acid component (B) per 100 parts by mass of the modified conjugated diene polymer (A) is less than 0.1 parts by mass, the effect of improving the stability over time of the polymer composition cannot be sufficiently obtained. Furthermore, if the content of the acid component (B) per 100 parts by mass of the modified conjugated diene polymer (A) is more than 20 parts by mass, the performance of the modified conjugated diene polymer (A) is likely to deteriorate. From these viewpoints, the content of the acid component (B) per 100 parts by mass of the modified conjugated diene polymer (A) is preferably 0.15 parts by mass or more, more preferably 0.2 parts by mass or more. The content of the acid component (B) is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the modified conjugated diene polymer (A).

[0099] <Solvent Removal Step> In the solvent removal step, the solvent is removed from the mixed liquid SC to isolate the polymer composition. The method for removing the solvent from the mixed liquid SC is not particularly limited, and can be any known solvent removal method, such as a method of separating the solvent by steam stripping and then dehydrating and drying the resulting polymer composition, a method of devolatilizing using a twin-screw extruder or the like, or a method of directly devolatilizing using a drum dryer or the like. Of these, the method of removing the solvent by bringing the mixed liquid SC into contact with water is preferred because it allows for easy solvent removal treatment.

[0100] According to the production method including the mixing step and the solvent removal step, a solid polymer composition from which the solvent has been removed can be obtained. The obtained polymer composition is a crumb or rubber bale containing the modified conjugated diene polymer (A) and the acid component (B).

[0101] <<Blend>> The blend of the present disclosure (hereinafter also referred to as "the present blend") is a composition obtained by blending the above-described polymer composition of the present disclosure with a filler.

[0102] <Component (E): Filler> A filler is blended into the present blend to increase the strength of the crosslinked body. Examples of fillers include silica, carbon black, inorganic compounds represented by the following formula (9) (hereinafter also referred to as "inorganic compound (N)"), and reinforcing fibers (e.g., inorganic fibers such as glass fiber and carbon fiber, and organic fibers such as nylon and polyester). Of these, the filler is preferably at least one selected from the group consisting of silica, carbon black, and inorganic compound (N). nM ２ mSiO ｋ ・iH ２ O...(9) (In formula (9), M ２ is at least one selected from the group consisting of a specific metal, which is any one of aluminum, magnesium, titanium, and calcium, an oxide of the specific metal, a hydroxide of the specific metal, and a carbonate of the specific metal; n is an integer of 1 to 5, m is an integer of 0 to 10, k is an integer of 2 to 5, and i is an integer of 0 to 10.

[0103] Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), colloidal silica, precipitated silica, calcium silicate, aluminum silicate, and silica derived from rice husks. Among these, wet silica is particularly preferred from the viewpoint of improving fracture properties and achieving both wet grip and low rolling resistance. Highly dispersible silica is also preferred from the viewpoint of improving dispersibility in the compound and improving physical properties and processability. Silica may be used alone or in combination of two or more types. The silica content in the compound (the total amount when two or more types are contained) is preferably 5 to 200 parts by mass, more preferably 10 to 150 parts by mass, and even more preferably 15 to 120 parts by mass, per 100 parts by mass of the total rubber components contained in the compound.

[0104] In this specification, the term "rubber component" refers to a polymer that can be cured to give a cured product exhibiting rubber elasticity. The cured product exhibits the property of undergoing large deformation under small force at room temperature (for example, stretching to more than twice its original size when stretched at room temperature) and rapidly returning to almost its original shape when the force is removed.

[0105] Examples of carbon black include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, etc. In the present compound, the blending ratio of carbon black (the total amount when two or more types are contained) is preferably 5 to 100 parts by mass, more preferably 5 to 50 parts by mass, per 100 parts by mass of the total amount of the rubber components contained in the present compound. In addition to silica and carbon black as inorganic fillers, the present compound may further contain various reinforcing fillers such as clay and calcium carbonate.

[0106] Specific examples of the inorganic compound (N) include compounds in which the specific metal is aluminum, such as aluminum oxide, alumina monohydrate, aluminum hydroxide, aluminum carbonate, aluminum silicate, and calcium aluminum oxide (Al ２ O ３ CaO 2SiO ４ and the like); compounds in which the specific metal is magnesium include, for example, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium silicate, and calcium magnesium silicate (CaMgSiO ４ ), talc, etc.; compounds in which the specific metal is titanium include, for example, titanium oxide, etc.; and compounds in which the specific metal is calcium include, for example, calcium oxide, calcium hydroxide, calcium carbonate, calcium silicate, etc.

[0107] As the filler, one of silica, carbon black, and inorganic compound (N) may be used alone, or two or more of these may be used in combination. In view of the high effect of improving tire properties when combined with the modified conjugated diene polymer (A), it is preferable that the compound contains silica as a filler, and it is preferable to use wet silica, dry silica, or colloidal silica.

[0108] The blending ratio of the filler in the present blend (the total amount when two or more types are contained) is preferably 25 to 300 parts by mass, more preferably 30 to 200 parts by mass, and even more preferably 50 to 150 parts by mass per 100 parts by mass of the total amount of the rubber components contained in the present blend.

[0109] <Other Components> The present blend may further contain components (other components) different from the polymer composition and filler of the present disclosure described above, as long as the effects of the present disclosure are not impaired. Other components that can be contained in the present blend will be described below.

[0110] Component (F): Other Rubber Component The present compound may further contain a rubber component (hereinafter also referred to as "other rubber component") different from the modified conjugated diene polymer (A).

[0111] The type of other rubber component is not particularly limited, but unmodified rubber is preferred, and examples thereof include butadiene rubber (BR, for example, high-cis BR having 90% or more cis-1,4 bonds), styrene-butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, hydrogenated butadiene rubber, hydrogenated styrene-butadiene rubber, and ethylene-butadiene rubber. The amount of the other rubber component is preferably 5 to 60 parts by mass, more preferably 10 to 50 parts by mass, per 100 parts by mass of the total amount of the rubber components (modified conjugated diene polymer (A) and other rubber components) contained in the blend. In this specification, the modified conjugated diene polymer (A) and other rubber components are collectively referred to as simply "rubber components."

[0112] Component (G): Crosslinking Agent The compound typically contains a crosslinking agent. Examples of crosslinking agents include sulfur, sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having methylol groups, with sulfur typically being used. The amount of sulfur blended is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the total rubber components contained in the compound.

[0113] Component (H): Resin The present compound may contain a thermoplastic or thermosetting resin (hereinafter simply referred to as "resin (H)"). From the viewpoint of obtaining a vulcanized rubber with excellent properties such as strength, abrasion resistance, and crack growth resistance, the resin (H) is preferably at least one selected from the group consisting of styrene-based resins, polyethylene, C5-based resins, C9-based resins, C5 / C9-based resins, dicyclopentadiene-based resins, dicyclopentadiene / C9-based resins, alkylphenol-based resins, terpene-based resins, and hydrogenated versions of these resins. Thermoplastic resins are particularly preferred as the resin (H) because of their high effect of improving various properties such as strength, abrasion resistance, and crack growth resistance. As the resin (H), one type may be used alone, or two or more types may be used in combination.

[0114] Here, the styrene-based resin is a polymer obtained using a styrene-based monomer, and in particular, a polymer having structural units derived from a styrene-based monomer in an amount of 20 mass% or more relative to the total amount of monomer units possessed by the styrene-based resin is preferred. Examples of the styrene-based monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene. Of these, the styrene-based monomer is preferably at least one of styrene and α-methylstyrene.

[0115] The styrene-based resin may be a homopolymer obtained by polymerizing one type of styrene-based monomer, or a copolymer obtained by copolymerizing two or more types of styrene-based monomers. The styrene-based resin may also be a copolymer obtained by using a styrene-based monomer and another monomer copolymerizable with the styrene-based monomer. Examples of the other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, and α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof.

[0116] The softening point of the styrene-based resin is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. When the softening point is 30°C or higher, the effect of improving crack growth resistance tends to be easily obtained in a crosslinked body obtained using the blend. Furthermore, the softening point of the styrene-based resin is preferably 160°C or lower, more preferably 130°C or lower, and even more preferably 100°C or lower. When the softening point is 160°C or lower, the dispersibility of the resin becomes good, and crack growth resistance, abrasion resistance, and breaking strength tend to be easily improved. In this specification, the softening point of the styrene-based resin is a value measured using a ring and ball softening point analyzer according to the method specified in JIS K 6220-1:2015, and is the temperature at which the sample softens and a ball placed on the sample drops onto the bottom plate.

[0117] The styrene-based resin may also be a block polymer (thermoplastic elastomer) having a conjugated diene polymer block as a soft segment and a polystyrene block as a hard segment. The use of such a block polymer is preferred because it can further enhance the effect of improving crack growth resistance. The conjugated diene polymer block of the block polymer may have some of the carbon-carbon double bonds in the structural unit derived from the conjugated diene compound hydrogenated.

[0118] Examples of conjugated diene compounds constituting the conjugated diene polymer block include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. These conjugated diene compounds can be used singly or in combination of two or more. The conjugated diene compound is preferably at least one of 1,3-butadiene and isoprene. The content of the conjugated diene unit in the block polymer is preferably 20% by mass or more, and more preferably 30% by mass or more. Furthermore, the content of the conjugated diene unit is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0119] The content of the polystyrene block in the block polymer is preferably 20% by mass or more, from the viewpoint of increasing the breaking strength. The content of the polystyrene block is preferably 80% by mass or less, and more preferably 70% by mass or less. The respective contents of the polystyrene block, the conjugated diene polymer block, and the conjugated diene unit in the block polymer are as follows: １ It can be calculated from the integral ratio of the H-NMR spectrum.

[0120] Specific examples of the block polymer include styrene-butadiene block copolymers, styrene-isoprene block copolymers, epoxidized styrene-butadiene block copolymers, and block copolymers in which a portion of the conjugated diene polymer block contained in a styrene-butadiene block copolymer or a styrene-isoprene block copolymer has been hydrogenated. More specifically, examples include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-butylene-styrene block copolymers (SBBS), and epoxidized styrene-butadiene-styrene block copolymers, as well as hydrogenated products of these copolymers. Among these, SBS or SIS having a conjugated diene polymer block in which the soft segment is not hydrogenated, or epoxidized styrene-butadiene-styrene block copolymers, are preferred as the block polymers, since they have sufficient crosslinking points.

[0121] Examples of polyethylene include low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), etc. C5 resins are produced by catalyzing a C5 fraction with a Friedel-Crafts catalyst (AlCl ３ or BF ３It is a solid polymer (C5 synthetic petroleum resin) obtained by polymerization using isoprene, cyclopentadiene, 1,3-pentadiene, 1-pentene, etc. Specific examples of C5 resins include copolymers mainly composed of isoprene, cyclopentadiene, 1,3-pentadiene, 1-pentene, etc., copolymers of 2-pentene and dicyclopentadiene, and polymers mainly composed of 1,3-pentadiene.

[0122] C9 resins were prepared by subjecting C9 fraction to Friedel-Crafts catalyst (AlCl ３ or BF ３ C5 / C9 resins are solid polymers (C9 synthetic petroleum resins) obtained by polymerization using a Friedel-Crafts catalyst (AlCl) or the like. Specific examples of C9 resins include copolymers containing indene, methylindene, vinyltoluene, or the like as the main component. C5 / C9 resins are produced by polymerization of C5 to C9 fractions using a Friedel-Crafts catalyst (AlCl). ３ or BF ３ It is a solid polymer (C5 / C9 synthetic petroleum resin) obtained by polymerization using a copolymer of vinyl toluene, indene, or the like. Specific examples of C5 / C9 resins include copolymers mainly composed of vinyl toluene, indene, or the like. From the viewpoint of compatibility with rubber components, C5 / C9 resins with a small amount of C9 or higher components are preferred. Specifically, the C5 / C9 resin preferably contains less than 50% by mass, and more preferably 40% by mass or less, of the total amount of the resin containing C9 or higher components.

[0123] Dicyclopentadiene-based resins are petroleum resins that use dicyclopentadiene in C5 fractions as the main raw material. Specific examples of dicyclopentadiene-based resins include the "Marukarets M" series (M-890A, M-845A, M-990A, etc.) manufactured by Maruzen Petrochemical Co., Ltd. Examples of alkylphenol-based resins include alkylphenol-acetylene resins such as p-tert-butylphenol-acetylene resins, and low-polymerization alkylphenol-formaldehyde resins.

[0124] Terpene resins are solid resins obtained by blending turpentine oil, which is obtained simultaneously when rosin is obtained from pine trees, or a polymerization component separated from the turpentine oil, and polymerizing the blend using a Friedel-Crafts catalyst, and examples of such resins include β-pinene resin and α-pinene resin. Commercially available terpene resins can be used, and examples include the "Picolite" series (A115, S115, etc.) manufactured by Hercules.

[0125] A representative example of a terpene-aromatic compound resin is terpene-phenol resin. This terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst or by further condensing them with formalin. There are no particular limitations on the terpenes used as raw materials; monoterpene hydrocarbons such as α-pinene and limonene are preferred, with those containing α-pinene being more preferred, and α-pinene being particularly preferred. In the present disclosure, terpene-phenol resins with a low ratio of phenolic components are preferred. Here, "low ratio of phenolic components" refers to a phenolic component content of less than 50% by mass, preferably 40% by mass or less, of the total resin. Using a terpene-aromatic compound resin, particularly a terpene-phenol resin, as resin (H) can further improve handling performance. Commercially available terpene-aromatic compound resins can be used, including, for example, "Tamanol 803L" and "Tamanol 901" (manufactured by Arakawa Chemical Industries, Ltd.).

[0126] The blending ratio of resin (H) is preferably 1 part by mass or more per 100 parts by mass of the rubber component contained in this blend. Blending 1 part by mass or more of resin (H) is preferable because the effect of improving abrasion resistance, breaking strength, and crack growth resistance by adding resin (H) can be sufficiently enhanced in the crosslinked product obtained using this blend. The blending ratio of resin (H) is more preferably 3 parts by mass or more, and even more preferably 7 parts by mass or more per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of maintaining various performance properties of the blend well, the blending ratio of resin (H) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less per 100 parts by mass of the rubber component contained in this blend. As resin (H), one type may be used alone, or two or more types may be used in combination.

[0127] Component (I): Silane Coupling Agent The present formulation may further contain a silane coupling agent. When the present formulation contains silica, the reinforcing effect of the silica can be further enhanced by further adding a silane coupling agent. There are no particular restrictions on the silane coupling agent, but sulfur-containing silane coupling agents are preferred. Examples of sulfur-containing silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, (3-[ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol, and NXT and NXT-Z manufactured by Momentive Corporation.

[0128] When a silane coupling agent is blended into the present formulation, the blending amount of the silane coupling agent is preferably 1 to 20 parts by mass per 100 parts by mass of silica. By blending the silane coupling agent in an amount of 1 part by mass or more per 100 parts by mass of silica, the effect of improving the dispersibility of silica can be sufficiently obtained. On the other hand, by blending the silane coupling agent in an amount of 20 parts by mass or less per 100 parts by mass of silica, the dispersibility of silica can be improved while maintaining good processability of the formulation and elongation at break of the crosslinked product. In the present formulation, the blending amount of the silane coupling agent is more preferably 5 to 15 parts by mass per 100 parts by mass of silica. As the silane coupling agent, only one type may be used, or two or more types may be used in combination.

[0129] Component (D): Extender Oil The present compound may contain a process oil commonly used to extend elastomers as an oil for oil extension (extender oil). The method for adding the process oil is not particularly limited. For example, the process oil may be incorporated into the present compound by directly adding it during kneading to obtain a rubber compound, which is one form of the present compound. Preferred process oils include various oils known in the art, such as the same oils exemplified as the extender oils that may be contained as optional components in the polymer composition of the present disclosure. The amount of process oil incorporated is preferably 0.05 to 100 parts by mass per 100 parts by mass of the total amount of rubber components contained in the present compound.

[0130] In addition to the components described above, the present compound may contain various additives that are generally used in compounds used to produce crosslinked products such as tires, such as antioxidants, zinc oxide, stearic acid, softeners, sulfur, vulcanization accelerators, compatibilizers, vulcanization aids, processing aids, and scorch inhibitors. The amounts of these additives added may be selected appropriately depending on the various components, as long as they do not impair the effects of the present disclosure.

[0131] The present blend can be obtained by blending the above-mentioned various components into the polymer composition of the present disclosure as needed. The present blend can be obtained by mixing the polymer composition of the present disclosure with various additives that are optionally used in blends for obtaining a crosslinked product (i.e., vulcanized rubber), and kneading the mixture using a kneader such as an open kneader (e.g., a roll) or an internal kneader (e.g., a Banbury mixer).

[0132] <<Method for Producing Crosslinked Product>> A crosslinked product (i.e., vulcanized rubber) can be obtained by crosslinking (vulcanizing) the compound obtained above after molding. The vulcanized rubber can be obtained, for example, by a method including the following kneading step.

[0133] - Kneading Step In the kneading step, first, the above-described polymer composition (i.e., the present composition) and additives other than the vulcanization compounding agents (crosslinking agent, vulcanization accelerator, vulcanization aid) (hereinafter also referred to as "first additive") are melt-kneaded using a kneader (first step). The first additive preferably contains at least a filler. The kneading temperature in the first step can be appropriately set depending on the melting point, glass transition point, etc. of the polymer component. This melt-kneading allows the first additive to be mixed with the polymer component, thereby sufficiently achieving effects such as increasing the strength of the rubber product after vulcanization, improving the kneading processability of the polymer composition, and preventing rubber degradation due to radicals generated during kneading.

[0134] Next, the kneaded product obtained in the first step is returned to room temperature as necessary, and then vulcanization compounding agents are added to the kneaded product, followed by melt-kneading using a kneader (second step). The compound obtained in the second step is molded and processed, and then crosslinked (vulcanized) to obtain a crosslinked product.

[0135] <Crosslinked Product and Tire> The crosslinked product obtained using the present composition is applicable to various rubber products. Specific examples of various rubber products include tire applications such as tire treads, undertreads, carcasses, sidewalls, and bead portions; sealing materials such as packings, gaskets, weatherstrips, and O-rings; interior and exterior covering materials for various vehicles such as automobiles, ships, aircraft, and railways; building materials; vibration-proof rubbers for industrial machinery and equipment; diaphragms, rolls, various hoses and hose covers such as radiator hoses and air hoses; belts such as power transmission belts; linings; dust boots; medical device materials; fenders; insulating materials for electric wires; and other industrial products.

[0136] The present composition can provide a crosslinked product having good tensile properties, low rolling resistance, and excellent fuel economy performance, making the composition particularly suitable as a material for either or both of the tread and sidewall of a tire.

[0137] Tires can be manufactured by conventional methods. For example, a mixture containing the polymer composition of the present disclosure and components blended as necessary (the compound of the present disclosure) is mixed in a kneader, formed into a sheet, and then placed in a predetermined position and vulcanized and molded by conventional methods to form a tread rubber, a sidewall rubber, or both, to obtain a pneumatic tire.

[0138] The present disclosure as described above provides the following means: [Means 1] A polymer composition comprising a modified conjugated diene-based polymer and an acid component, and optionally containing one or both of a nonionic surfactant and an extender oil, the acid component being an acid or a metal salt thereof, or both, the content of the acid component being 0.1 to 20 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, the content of the nonionic surfactant being 0 to 5 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, the content of the extender oil being 0 to 50 parts by mass relative to 100 parts by mass of the modified conjugated diene-based polymer, the total amount of the modified conjugated diene-based polymer, the acid component, the nonionic surfactant, and the extender oil being 95% by mass or more of the entire composition, and the modified conjugated diene-based polymer having a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups. [Means 2] The polymer composition of [Means 1], wherein the nitrogen-containing group is one or more selected from the group consisting of a protected primary amino group, a protected secondary amino group, a tertiary amino group, an imino group, and an imidazolyl group. [Means 3] The polymer composition of [Means 1] or [Means 2], wherein the modified conjugated diene polymer has a partial structure derived from compound (M) and a plurality of conjugated diene polymer chains bonded to the partial structure derived from compound (M). [Means 4] The polymer composition of [Means 3], wherein at least some of the plurality of conjugated diene polymer chains have a partial structure derived from a nitrogen-containing compound at their ends. [Means 5] The polymer composition of any of [Means 1] to [Means 4], wherein the acid constituting the acid component has a pH of 2 to 5 at 20°C. [Means 6] The polymer composition of any of [Means 1] to [Means 5], wherein the acid component has a solubility in cyclohexane at 25°C of 1.0 g / L or more. [Means 7] The polymer composition of any one of [Means 1] to [Means 6], wherein the acid constituting the acid component is an organic acid. [Means 8] The polymer composition of any one of [Means 1] to [Means 7], wherein the nonionic surfactant is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the modified conjugated diene-based polymer. [Means 9] A blend obtained by blending the polymer composition of any one of [Means 1] to [Means 7] and a filler.[Means 10] The blend of [Means 9] further containing a resin. [Means 11] A crosslinked body obtained by crosslinking the blend of [Means 9] or [Means 10]. [Means 12] A tire comprising a tread, a sidewall, or both, wherein the tread, the sidewall, or both are produced using the blend of [Means 9] or [Means 10]. [Means 13] A method for producing a polymer composition, comprising the steps of: mixing a modified conjugated diene polymer and an acid component in an organic solvent in a ratio of 0.1 to 20 parts by mass of the acid component per 100 parts by mass of the modified conjugated diene polymer to obtain a mixture; and removing the solvent from the mixture, wherein the acid component is an acid or a metal salt thereof, or both, and the modified conjugated diene polymer has a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups. [Means 14] A method for producing a polymer composition according to [Means 13], further comprising the steps of: polymerizing a monomer containing a conjugated diene compound in the presence of at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds to obtain a conjugated diene polymer having an active terminal; and reacting the conjugated diene polymer having an active terminal with a compound (M) having one or more nitrogen-containing groups selected from the group consisting of a protected primary amino group, a protected secondary amino group, a tertiary amino group, an imino group, and an imidazolyl group, and two or more hydrocarbyloxysilyl groups to obtain the modified conjugated diene polymer.

[0139] The present invention will be described in detail below based on examples, but is not limited to these examples. In the following synthesis examples, examples, and comparative examples, "parts" and "%" are by mass unless otherwise specified. The methods for measuring various physical properties of the polymer and polymer composition P (polymer composition before blending with a filler) are shown below.

[0140] Bound styrene content (%): Using deuterated chloroform as a solvent, １ Calculated by H-NMR measurement. Vinyl group content (%): 400 MHz １Calculations were made by H-NMR measurement. Weight average molecular weight and molecular weight distribution of polymer: A chart (GPC curve) based on the molecular weight converted to polystyrene was obtained by gel permeation chromatography (GPC), and the weight average molecular weight and molecular weight distribution were determined based on this chart. Specific measurement conditions for GPC are as follows. (GPC measurement conditions) Measurement instrument: HLC-8020 (manufactured by Tosoh Corporation) Column: Two GMH-HR-H (manufactured by Tosoh Corporation) connected in series Detector: Differential refractometer RI-8020 (manufactured by Tosoh Corporation) Eluent: Tetrahydrofuran Column temperature: 40°C Flow rate: 1.0 mL / min Sample concentration: 10 mg / 20 mL

[0141] Mooney viscosity (ML1+4, 100°C): Polymer composition P described below was used as a measurement sample and measured using a Mooney tester (manufactured by Alpha Technology). According to JIS K6300 (ISO289-1) and ISO289-4, the sample was first preheated for 1 minute at a temperature of 100°C, and then the rotor was rotated at 2 rpm. The torque after 4 minutes was measured, and this measurement value was taken as the Mooney viscosity (ML(1+4)). The smaller the Mooney viscosity value, the better the processability of the polymer composition. The MV measured by using each polymer composition P immediately after drying with a heated roll as the measurement sample was taken as the "MV immediately after production." The "MV 90 days after production" was measured in the same manner as above, using each polymer composition P that had been dried with a heated roll and then stored at 25°C for 90 days as the measurement sample. The difference between the MV 90 days after production and the MV immediately after production was taken as the MV change, and the ratio of the MV change to the MV immediately after production was taken as the MV change rate (%). A smaller MV change rate indicates less deterioration in the performance of the polymer composition over time.

[0142] pH pH of organic acid: The pH of a liquid obtained by mixing 1.0 g of acid with 1.0 L of purified water was measured at 20°C using a pH meter (manufactured by Horiba, Ltd.). For organic acid salts, the pH of the organic acid constituting the salt was measured. pH of inorganic acid: The pH of a 0.1 mol / L aqueous solution of the acid used was measured at 20°C in the same manner as above.

[0143] Solubility: 1.0 g of an acid or a metal salt thereof was added to 1.0 L of cyclohexane, and the system was sealed and mixed at 25°C for 5 minutes. The mixture was allowed to stand for 10 minutes, and the state of the mixture was then visually observed. If phase separation or residual solids were observed in the mixture upon observation, the solubility of the acid or a metal salt thereof in cyclohexane was determined to be less than 1.0 g / L. If neither phase separation nor residual solids were observed, the solubility of the acid or a metal salt thereof in cyclohexane was determined to be 1.0 g / L or more.

[0144] 1. Synthesis of (Modified) Conjugated Diene Polymer and Preparation of Polymer Composition P [Example 1: Synthesis of Modified Conjugated Diene Polymer A1 and Preparation of Polymer Composition P1] 2,500 g of cyclohexane, 50 g of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 50 g of styrene and 400 g of 1,3-butadiene as monomers were charged into a nitrogen-purged 5-liter autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, 5.2 mmol of n-butyllithium was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. After confirming that the polymerization conversion rate had reached 99% (25 minutes after the start of polymerization), 50 g of 1,3-butadiene was added over 5 minutes. Thereafter, 1.0 mmol of a compound represented by the following formula (N-Si-1) was added and stirred for 10 minutes to obtain a polymer solution containing a modified conjugated diene polymer (referred to as polymer solution SA1). To the polymer solution SA1, 4.4 g of 2,6-di-tert-butyl-p-cresol was added as an antioxidant, and then 0.50 g of 2-ethylhexanoic acid was added to obtain a mixed solution (referred to as mixed solution SC1). Next, mixed solution SC1 was subjected to a solvent removal treatment under the solvent removal conditions shown below to obtain a rubber-like substance. The obtained rubber-like substance was dried using a heated roll adjusted to 110°C to obtain a polymer composition P1 containing the modified conjugated diene-based polymer A1 and 2-ethylhexanoic acid.

[0145] [Conditions for Desolvation] 200 g of the mixed solution SC1 and 300 g of deionized water are placed in a pressure vessel, and the solvent is removed by steam stripping (steam temperature: 190° C.) for 60 minutes.

[0146] Various physical property values ​​of the modified conjugated diene polymer A1 and the polymer composition P1 are shown in Table 1. The physical properties of the modified conjugated diene polymer A1 were measured using a polymer sample obtained by extracting a portion of the polymer solution SA1 and removing the solvent under conditions of 60°C and 0.1 mmHg for 24 hours.

[0147] [Examples 2 to 12, Example 19, Comparative Example 2] Modified conjugated diene polymers A2 to A12, A19, and A25, and polymer compositions P2 to P12, P19, and P25 were obtained by polymerization, desolvation, and drying in the same manner as in Example 1, except that the types and amounts of raw materials used were as shown in Tables 1 to 3. In Tables 1 to 3, the numerical values ​​for each component in the polymer compositions are values ​​determined from the blend amounts. Various physical property values ​​of the modified conjugated diene polymers A2 to A12, A19, and A25, and polymer compositions P2 to P12, P19, and P25 are shown in Tables 1 to 3.

[0148] Example 13 A 5-liter autoclave reactor purged with nitrogen was charged with 2,500 g of cyclohexane, 4.3 mmol of N-trimethylsilylpiperazine as an initiation terminal modifier, 50 g of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 50 g of styrene and 400 g of 1,3-butadiene as monomers. After adjusting the temperature of the reactor contents to 20°C, 5.2 mmol of n-butyllithium was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. After confirming that the polymerization conversion rate had reached 99% (25 minutes after the start of polymerization), 50 g of 1,3-butadiene was added over 5 minutes. Subsequently, 1.0 mmol of the compound represented by the formula N-Si-1 was added and stirred for 10 minutes. To the resulting polymer solution containing the modified conjugated diene polymer (referred to as polymer solution SA13), 4.4 g of 2,6-di-tert-butyl-p-cresol was added as an antioxidant, and then 5.0 g of 2-ethylhexanoic acid was added to obtain a mixed solution (referred to as mixed solution SC13). Next, mixed solution SC13 was subjected to a solvent removal treatment under the solvent removal conditions shown above to obtain a rubber-like substance. The obtained rubber-like substance was dried using a heated roll adjusted to 110°C to obtain polymer composition P13 containing modified conjugated diene polymer A13 and 2-ethylhexanoic acid. Various physical property values ​​of modified conjugated diene polymer A13 and polymer composition P13 are shown in Table 2.

[0149] Example 14 A modified conjugated diene polymer A14 and a polymer composition P14 were obtained by carrying out polymerization, desolvation, and drying in the same manner as in Example 3, except that 5.0 g of polyoxyalkylene alkylamine (trade name "FT-6020J", Lion Specialty Chemicals) was added as a nonionic surfactant after the addition of 2-ethylhexanoic acid. The physical properties of the modified conjugated diene polymer A14 and the polymer composition P14 are shown in Table 2.

[0150] Modified conjugated diene polymers A15 and A16 and polymer compositions P15 and P16 were obtained by polymerization, desolvation, and drying in the same manner as in Example 3, except that the type and amount of the nonionic surfactant were changed as shown in Table 2. Table 2 shows the physical properties of the modified conjugated diene polymers A15 and A16 and the polymer compositions P15 and P16.

[0151] Example 17 Polymerization, desolvation, and drying were carried out in the same manner as in Example 13, except that 5.0 g of polyoxyalkylene alkylamine (trade name "FT-6020J", Lion Specialty Chemicals) was added as a nonionic surfactant after the addition of 2-ethylhexanoic acid, to obtain a modified conjugated diene polymer A17 and a polymer composition P17. The physical properties of the modified conjugated diene polymer A17 and the polymer composition P17 are shown in Table 2.

[0152] Example 18 A 5-liter autoclave reactor purged with nitrogen was charged with 2,500 g of cyclohexane, 4.3 mmol of N-trimethylsilylpiperazine as an initiation terminal modifier, 50 g of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 50 g of styrene and 400 g of 1,3-butadiene as monomers. After adjusting the temperature of the reactor contents to 20°C, 5.2 mmol of n-butyllithium was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, with the maximum temperature reaching 85°C. After confirming that the polymerization conversion rate had reached 99% (25 minutes after the start of polymerization), 50 g of 1,3-butadiene was added over 5 minutes. Subsequently, 2.0 mmol of the compound represented by the formula N-Si-3 was added and the mixture was stirred for 10 minutes. Subsequently, 5.2 mmol of n-butyllithium was added and the mixture was stirred for an additional 10 minutes. To the resulting polymer solution containing the modified conjugated diene polymer (referred to as polymer solution SA18), 4.4 g of 2,6-di-tert-butyl-p-cresol was added as an antioxidant, and then 5.0 g of 2-ethylhexanoic acid was added to obtain a mixed liquid (referred to as mixed liquid SC18). Next, mixed liquid SC18 was subjected to a solvent removal treatment under the solvent removal conditions shown above to obtain a rubber-like substance. The obtained rubber-like substance was dried using a heated roll adjusted to 110°C to obtain polymer composition P18 containing modified conjugated diene polymer A18 and 2-ethylhexanoic acid. The various physical properties of modified conjugated diene polymer A18 and polymer composition P18 are shown in Table 2.

[0153] Comparative Example 1 Polymerization, desolvation, and drying were carried out in the same manner as in Example 1, except that 2-ethylhexanoic acid was not added, to obtain a modified conjugated diene polymer A24 and a polymer composition P24. The physical properties of the modified conjugated diene polymer A24 and the polymer composition P24 are shown in Table 3. Comparative Example 3 Polymerization, desolvation, and drying were carried out in the same manner as in Example 14, except that 2-ethylhexanoic acid was not added, to obtain a modified conjugated diene polymer A26 and a polymer composition P26. The physical properties of the modified conjugated diene polymer A26 and the polymer composition P26 are shown in Table 3.

[0154] Comparative Example 4 A polymer solution containing a modified conjugated diene polymer (referred to as polymer solution SA27) was obtained by polymerization according to the polymerization recipe shown in Table 3, and then polymerization, desolvation, and drying were carried out in the same manner as in Comparative Example 1, except that 5.0 g of 1-decanol was added to this polymer solution SA27, thereby obtaining a modified conjugated diene polymer A27 and a polymer composition P27. The various physical property values ​​of the modified conjugated diene polymer A27 and the polymer composition P27 are shown in Table 3.

[0155] Comparative Example 5 Polymerization, desolvent removal, and drying were carried out in the same manner as in Example 13, except that 2-ethylhexanoic acid was not added, to obtain a modified conjugated diene polymer A28 and a polymer composition P28. The physical properties of the modified conjugated diene polymer A28 and the polymer composition P28 are shown in Table 3. Comparative Example 6 Polymerization, desolvent removal, and drying were carried out in the same manner as in Example 13, except that 2-ethylhexanoic acid was not added after the addition of the antioxidant, and 5.0 g of polyoxyalkylene alkylamine (trade name "FT-6020J", Lion Specialty Chemicals) was added as a nonionic surfactant, to obtain a modified conjugated diene polymer A29 and a polymer composition P29. The physical properties of the modified conjugated diene polymer A29 and the polymer composition P29 are shown in Table 3.

[0156] Comparative Example 7 Another conjugated diene polymer OA1 and a polymer composition OP1 were obtained by carrying out polymerization, desolvation, and drying in the same manner as in Example 1, except that the types and amounts of raw materials used were as shown in Table 3. Various physical property values ​​of the other conjugated diene polymer OA1 and the polymer composition OP1 are shown in Table 3. Note that N-Si-4 used as the terminal modifier in Comparative Example 7 is a compound having one hydrocarbyloxysilyl group, and the other conjugated diene polymer OA1 is a linear polymer.

[0157]

[0158]

[0159]

[0160] The abbreviations in Tables 1 to 3 are as follows: (Initial terminal modifier) ​​Ini-1: N-trimethylsilylpiperazine (Terminal modifier) ​​N-Si-1: Compound represented by the following formula N-Si-1 N-Si-2: Compound represented by the following formula N-Si-2 N-Si-3: Compound represented by the following formula N-Si-3 N-Si-4: N,N-dimethylaminopropylmethyldiethoxysilane N-Si-5: Compound represented by the following formula N-Si-5

[0161] (Acids or metal salts thereof) b-1: 2-ethylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) b-2: Phthalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) b-3: Hydrochloric acid (0.1 mol / L) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) b-4: Bis(2-ethylhexyl)phosphate (manufactured by Tokyo Chemical Industry Co., Ltd.) b-5: Tin bis(2-ethylhexanoate) (manufactured by Tokyo Chemical Industry Co., Ltd.) Note that b-1, b-2, b-4, and b-5 have a solubility in cyclohexane at 25°C of 1.0 g / L or more, and b-3 has a solubility in cyclohexane at 25°C of less than 1.0 g / L.

[0162] (Nonionic surfactants) c-1: FT-6020J (Lion Specialty Chemicals, nonionic surfactant, polyoxyalkylene alkylamine) c-2: Nymeen S-210 (NOF Corp., nonionic surfactant, polyoxyethylene stearylamine) c-3: Rheostat GS-95P (Lion Specialty Chemicals, nonionic surfactant, glycerin fatty acid ester)

[0163] Example 20 A 50-liter autoclave reactor (first reactor) purged with nitrogen was continuously charged with 26.6 g / min of 1,3-butadiene as monomers, 2.95 g / min of styrene, 180.2 g / min of cyclohexane as solvent, 0.40 g / min of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 0.25 mmol / min of n-butyllithium as a polymerization initiator, and the temperature inside the reactor was controlled at 75° C. The polymer solution was continuously decharged from the first reactor at a rate of 210.2 g / min, and the compound represented by the above formula N—Si-1 was added to the decharged polymer solution at a rate of 0.05 mmol / min, and the mixture was continuously introduced into the second reactor to carry out the reaction. At the outlet of the second reactor, di-tert-butyl-p-cresol was added as an antioxidant in an amount of 0.88 parts by mass per 100 parts by mass of the polymer, followed by the addition of extender oil at a rate of 7.4 g / min. To the polymer solution containing the modified conjugated diene polymer A20 thus produced (referred to as polymer solution SA20), 2-ethylhexanoic acid was added at a rate of 0.295 g / min to obtain a mixed solution (referred to as mixed solution SC20). Next, mixed solution SC20 was subjected to a solvent removal treatment under the solvent removal conditions described above to obtain a rubber-like substance. The obtained rubber-like substance was dried using a heated roll adjusted to 110°C to obtain polymer composition P20 containing the modified conjugated diene polymer A20 and 2-ethylhexanoic acid.

[0164] The various physical properties of the modified conjugated diene polymer A20 and the polymer composition P20 are shown in Table 4. The physical properties of the modified conjugated diene polymer A20 were measured using a polymer sample obtained by withdrawing a portion of the polymer solution after the addition of the antioxidant but before the addition of the extender oil from the polymerization line and removing the solvent under conditions of 60°C and 0.1 mmHg for 24 hours. The abbreviations in Table 4 are the same as those in Tables 1 to 3.

[0165] Example 21 Polymerization, desolvation, and drying were carried out in the same manner as in Example 20, except that tin bis-2-ethylhexanoate was added instead of 2-ethylhexanoic acid, to obtain a modified conjugated diene polymer A21 and a polymer composition P21. The various physical properties of the modified conjugated diene polymer A21 and the polymer composition P21 are shown in Table 4. Example 22 Polymerization, desolvation, and drying were carried out in the same manner as in Example 20, except that a mixture of n-butyllithium and N-trimethylsilylpiperazine (1 / 1, molar ratio) was added at 0.25 mmol / min instead of n-butyllithium as the polymerization initiator, to obtain a modified conjugated diene polymer A22 and a polymer composition P22. The various physical properties of the modified conjugated diene polymer A22 and the polymer composition P22 are shown in Table 4. Example 23 Polymerization, desolvation, and drying were carried out in the same manner as in Example 22, except that after the addition of 2-ethylhexanoic acid, polyoxyalkylene alkylamine (trade name "FT-6020J", Lion Specialty Chemicals) was added as a nonionic surfactant in an amount of 0.88 parts by mass per 100 parts by mass of the polymer, to obtain a modified conjugated diene polymer A23 and a polymer composition P23. The physical properties of the modified conjugated diene polymer A23 and the polymer composition P23 are shown in Table 4.

[0166] Comparative Example 8 Polymerization, desolvation, and drying were carried out in the same manner as in Example 20, except that 2-ethylhexanoic acid was not added, to obtain a modified conjugated diene polymer A30 and a polymer composition P30. The various physical property values ​​of the modified conjugated diene polymer A30 and the polymer composition P30 are shown in Table 4. Comparative Example 9 Polymerization, desolvation, and drying were carried out in the same manner as in Example 22, except that 2-ethylhexanoic acid was not added, to obtain a modified conjugated diene polymer A31 and a polymer composition P31. The various physical property values ​​of the modified conjugated diene polymer A31 and the polymer composition P31 are shown in Table 4.

[0167]

[0168] 2. Preparation of Compound Q [Examples 24 to 48, Comparative Examples 10 to 18] Compound Q was prepared by blending the components according to the formulations shown in Tables 5 to 7 and melt-kneading the blend. Kneading was carried out as follows. Using a batch mixer (manufactured by Toyo Seiki Seisakusho, Ltd.; trade name: Labo Plastomill) equipped with a temperature control device, the first stage of kneading was carried out by blending and kneading polymer composition P, polybutadiene rubber, extender oil, silica, carbon black, silane coupling agent, stearic acid, antioxidant, and zinc oxide under the following conditions: temperature was adjusted to 100°C, rotation speed was 60 rpm, and kneading time was 4 minutes. In Example 47, natural rubber was used instead of polybutadiene rubber. In Examples 42 and 44, polybutadiene rubber and natural rubber were used in combination, and a resin was further blended. The temperature of the kneaded mixture discharged from the mixer was always around 150°C. Next, in the second stage of mixing, the kneaded material obtained in the first stage of mixing was cooled to room temperature, and then a vulcanization accelerator and sulfur were blended into the mixer. The temperature was adjusted to 70°C, the rotation speed was 60 rpm, and the mixing time was 1.5 minutes, thereby obtaining each of Compounds Q (Q1 to Q34). The temperature of the kneaded material discharged from the mixer was 100°C or lower. Next, each of the obtained Compounds Q was vulcanized and molded in a vulcanization press at 160°C for a predetermined time, thereby obtaining vulcanized rubber as a crosslinked product. The obtained vulcanized rubbers were evaluated for the following physical properties. The results are shown in Tables 5 to 7.

[0169] [Physical properties of compound (initial)] Compound Q was produced by the above method using polymer composition P immediately after production, and the following physical properties were evaluated. Tensile strength (tensile product) A tensile test was carried out in accordance with JIS K6251:2010 using vulcanized rubber as a measurement sample. Here, a dumbbell No. 3 was used as the test sample, and the stress at break (TB, MPa) and elongation at break (EB, %) were measured at room temperature. The strength was calculated from the value of the tensile product (= (TB x EB)) and evaluated using an index based on Comparative Example 10. A larger value indicates better strength.

[0170] Loss tangent (3% tan δ @ 50°C rolling resistance) Using a vulcanized rubber as a measurement sample, the ratio of the loss modulus G" to the storage modulus G' (50°C tan δ) was measured using a shear dynamic spectrometer (manufactured by TA Instruments) under conditions of an angular velocity of 100 radians per second, a temperature of 50°C, and a shear strain of 3%. The ratio is expressed as an index, with Comparative Example 10 being set at 100, and a larger value indicates lower rolling resistance and better fuel economy.

[0171] Wet grip performance (0°C tan δ) Using vulcanized rubber as a measurement sample, the loss factor (tan δ (0°C)) was measured using an ARES-RDA (manufactured by TA Instruments) under conditions of a shear strain of 0.14%, an angular velocity of 100 radians per second, and 0°C. The measurement results are expressed as an index, with the result of Comparative Example 10 set to 100. The larger the value, the better the wet grip performance. Abrasion resistance (DIN abrasion) Using vulcanized rubber as a measurement sample, measurements were taken at 25°C under a load of 10N in accordance with JIS K6264 using a DIN abrasion tester (manufactured by Toyo Seiki Co., Ltd.). The measurement results are expressed as an index, with the result of Comparative Example 10 set to 100. The larger the value, the better the abrasion resistance.

[0172] [Blend properties (after 90 days)] Blend Q was produced by the above method using polymer composition P 90 days after production, and the same physical properties as those of [Blend properties (initial)] were evaluated. The results are shown as an index, with the value of Comparative Example 10 of [Blend properties (initial)] set to 100. When comparing [Blend properties (initial)] and [Blend properties (after 90 days)], the smaller the decrease in the index value, the smaller the change in performance over time and the better the result.

[0173]

[0174]

[0175]

[0176] Details of each component in Tables 5 to 7 are as follows: *1) ENEOS Materials, trade name "BR01" *2) ENEOS C5 resin, trade name "RA100" *3) Evonik, trade name "ZEOSIL 1165MP" *4) Mitsubishi Chemical, trade name "Diablack N330" *5) Evonik, trade name "Si75" *6) ENEOS process oil T-DAE *7) Seiko Chemical, trade name "Ozonone 6C" *8) Ouchi Shinko Chemical, trade name "Nocceler D" *9) Ouchi Shinko Chemical, trade name "Nocceler DZ-G"

[0177] As shown in Tables 5 to 7, in Examples 24 to 48 in which crosslinked bodies were produced using polymer compositions P1 to P23 containing the modified conjugated diene polymer (A) and the acid component (B), the crosslinked bodies were excellent in tensile properties, fuel economy, wet grip performance, and abrasion resistance, and further, there was little change in physical properties after long-term storage, and the crosslinked bodies were excellent in stability over time.

[0178] In contrast, Comparative Example 10, in which a polymer composition and a crosslinked body were produced in the same manner as in Example 24 except that the acid component (B) was not added, Comparative Example 11, in which the amount of acid component (B) in the polymer composition was as low as 0.05 parts by mass, and Comparative Example 13, in which a polymer composition and a crosslinked body were produced by adding 1-decanol instead of the acid component (B), showed a greater change in physical properties after long-term storage and were inferior in stability over time compared to Example 24. Furthermore, Comparative Example 14, in which a polymer composition and a crosslinked body were produced in the same manner as in Example 36 except that the acid component (B) was not added, and Comparative Example 12, in which a polymer composition and a crosslinked body were produced in the same manner as in Example 37 except that the acid component (B) was not added, each showed a greater change in physical properties after long-term storage compared to the results of the corresponding Examples. Similarly, Comparative Examples 16 to 18, in which modified conjugated diene-based polymers were produced by continuous polymerization, also showed results in which the change in physical properties after long-term storage was inferior to those of the Examples.

Claims

1. A polymer composition comprising a modified conjugated diene polymer and an acid component, and optionally containing one or both of a nonionic surfactant and an extender oil, the acid component being an acid or a metal salt thereof, or both, the acid component being 0.1 to 20 parts by mass relative to 100 parts by mass of the modified conjugated diene polymer, the nonionic surfactant being 0 to 5 parts by mass relative to 100 parts by mass of the modified conjugated diene polymer, and the extender oil being 0 to 50 parts by mass relative to 100 parts by mass of the modified conjugated diene polymer, the total amount of the modified conjugated diene polymer, the acid component, the nonionic surfactant and the extender oil being 95% by mass or more of the entire composition, and the modified conjugated diene polymer having a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups.

2. The polymer composition according to claim 1, wherein the nitrogen-containing group is one or more selected from the group consisting of a protected primary amino group, a protected secondary amino group, a tertiary amino group, an imino group, and an imidazolyl group.

3. The polymer composition according to claim 1, wherein the modified conjugated diene polymer has a partial structure derived from the compound (M) and a plurality of conjugated diene polymer chains bonded to the partial structure derived from the compound (M).

4. The polymer composition according to claim 3, wherein at least some of the ends of the plurality of conjugated diene polymer chains have a partial structure derived from a nitrogen-containing compound.

5. The polymer composition according to claim 1, wherein the acid constituting the acid component has a pH of 2 to 5 at 20° C.

6. The polymer composition according to claim 1, wherein the acid component has a solubility in cyclohexane at 25° C. of 1.0 g / L or more.

7. The polymer composition according to claim 1, wherein the acid constituting the acid component is an organic acid.

8. The polymer composition according to claim 1, wherein the nonionic surfactant is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the modified conjugated diene polymer.

9. A blend comprising the polymer composition according to any one of claims 1 to 8 and a filler.

10. The formulation of claim 9 further comprising a resin.

11. A crosslinked product obtained by crosslinking the compound according to claim 9.

12. A tire having a tread, a sidewall, or both, said tread, sidewall, or both being made with a compound according to claim 9.

13. A method for producing a polymer composition, comprising: a step of mixing a modified conjugated diene polymer and an acid component in an organic solvent in a ratio of 0.1 to 20 parts by mass of the acid component per 100 parts by mass of the modified conjugated diene polymer to obtain a mixture; and a step of removing the solvent from the mixture, wherein the acid component is an acid or a metal salt thereof, or both, and the modified conjugated diene polymer has a partial structure derived from a compound (M) having a nitrogen-containing group and two or more hydrocarbyloxysilyl groups.

14. A method for producing a polymer composition according to claim 13, further comprising the steps of: polymerizing a monomer containing a conjugated diene compound in the presence of at least one compound selected from the group consisting of alkali metal compounds and alkaline earth metal compounds to obtain a conjugated diene polymer having an active end; and reacting the conjugated diene polymer having an active end with a compound (M) having one or more nitrogen-containing groups selected from the group consisting of a protected primary amino group, a protected secondary amino group, a tertiary amino group, an imino group, and an imidazolyl group, and two or more hydrocarbyloxysilyl groups to obtain the modified conjugated diene polymer.

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