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

Abstract

The present invention achieves a polymer composition containing a conjugated diene-based polymer and a thermoplastic resin. An extender oil is included as an optional component. The softening point of the thermoplastic resin is 100-150°C. The content proportion of the thermoplastic resin having a softening point of 100-150°C is 5-20 parts by mass per 100 parts by mass of the conjugated diene-based polymer, the content proportion of the extender oil is 0-50 parts by mass per 100 parts by mass of the conjugated diene-based polymer, and the total amount of the conjugated diene-based polymer, the thermoplastic resin having a softening point of 100-150°C, and the extender oil is 90 mass% or more of the entire composition.

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. 2023-198719, filed on November 23, 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 fillers such as carbon black and silica are blended together with the conjugated diene polymer in compounds used in the production of treads, sidewalls, etc. of pneumatic tires in order to improve the durability and abrasion resistance of the products.

[0003] Furthermore, as the conjugated diene polymer, various proposals have been made to use modified conjugated diene polymers in which functional groups that interact with silica have been introduced into the chain ends or main chains of the conjugated diene polymer in order to obtain tires with better fuel economy (see, for example, Patent Documents 1 to 3).

[0004] International Publication No. 2008 / 123164 Japanese Patent Application Laid-Open No. 11-349632 International Publication No. 2017 / 221943

[0005] Due to recent environmental issues, growing awareness of resource and energy conservation, and rising consumer needs for safety, there is an ever-increasing demand for rubber materials for automobile tires that offer superior fuel efficiency (rolling resistance). Furthermore, rubber generally tends to harden and lose flexibility at low temperatures. Meanwhile, there is an ever-increasing demand for performance that allows stable handling even at low temperatures (driving stability).

[0006] 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 can give a crosslinked product that is excellent in fuel efficiency and handling stability at low temperatures.

[0007] 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 conjugated diene-based polymer and a specific resin. Specifically, the present disclosure provides the following polymer composition, a production method thereof, a compound, a crosslinked product, and a tire.

[0008] [1] A polymer composition comprising a conjugated diene polymer and a thermoplastic resin, and optionally containing an extender oil, wherein the thermoplastic resin has a softening point of 100 to 150°C, the content of the thermoplastic resin is 5 to 20 parts by mass per 100 parts by mass of the conjugated diene polymer, the content of the extender oil is 0 to 50 parts by mass per 100 parts by mass of the conjugated diene polymer, and the total amount of the conjugated diene polymer, the thermoplastic resin, and the extender oil is 90% by mass or more of the total composition. [2] A compound obtained by blending the polymer composition of [1] above with a filler. [3] A crosslinked body obtained by crosslinking the compound of [2] above. [4] A tire comprising a tread, a sidewall, or both, and wherein the tread, the sidewall, or both are made using the compound of [2] above. [5] A method for producing a polymer composition, comprising: a step of mixing a conjugated diene polymer and a thermoplastic resin in an organic solvent in a ratio of 5 to 20 parts by mass of the thermoplastic resin per 100 parts by mass of the conjugated diene polymer to obtain a mixture; and a step of removing the solvent from the mixture, wherein the thermoplastic resin has a softening point of 100°C to 150°C.

[0009] According to the present disclosure, a crosslinked product can be obtained that has an improved balance between fuel economy and handling stability at low temperatures.

[0010] 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.

[0011] In this specification, a numerical range described using "to" means that the numerical values ​​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."

[0012] The term "hydrocarbyloxysilyl group" refers to a monovalent or divalent group in which 1 to 3 hydrocarbyloxy groups are bonded to a silicon atom. That is, the hydrocarbyloxysilyl group is defined as "-Si(OR 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.

[0013] <Polymer Composition> The polymer composition of the present disclosure (hereinafter also referred to as "polymer composition P") contains a conjugated diene-based polymer (referred to as component (A)) and a thermoplastic resin having a softening point of 100 to 150°C (referred to as component (B)). In addition, polymer composition P may further contain an extender oil (referred to as component (C)) as an optional component. Hereinafter, each component contained in polymer composition P and optional components that are included will be described.

[0014] <Component (A): Conjugated Diene Polymer> As the conjugated diene polymer, a curable (preferably thermosetting) polymer having a structural unit derived from a conjugated diene compound can be used. Examples of the conjugated diene polymer 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, and hydrogenated styrene-butadiene rubber. The conjugated diene polymer may be unmodified or modified.

[0015] Here, in this specification, the term "modification" refers to imparting a partial structure containing a heteroatom such as nitrogen, oxygen, sulfur, or silicon to a conjugated diene polymer consisting of structural units derived from hydrocarbons (i.e., an unmodified conjugated diene polymer).

[0016] At least a portion of the conjugated diene polymer contained in the polymer composition P is preferably a modified conjugated diene polymer (hereinafter also referred to as "modified conjugated diene polymer (A1)"). By containing the modified conjugated diene polymer (A1) in the polymer composition P, when the polymer composition P is blended with a filler to prepare a blend, the dispersibility of the filler (particularly silica) in the blend can be improved. In terms of further improving the dispersibility of the filler in the blend, the modified conjugated diene polymer (A1) preferably has a monomer unit derived from a conjugated diene compound and at least one element selected from the group consisting of nitrogen, oxygen, silicon, sulfur, phosphorus, and tin (hereinafter also referred to as "specific element").

[0017] In terms of facilitating the introduction of a specific element into the polymer, the modified conjugated diene polymer (A1) preferably has a partial structure derived from a compound having the specific element (hereinafter also referred to as "compound (M)"). The compound (M) may be a compound capable of introducing a functional group having the specific element into the polymerization initiation terminal (hereinafter also referred to as "initiation terminal modifier"), or may be a compound capable of introducing a functional group having the specific element into the polymerization termination terminal (hereinafter also referred to as "terminal modifier"). The compound (M) may also be a monomer capable of introducing a functional group having the specific element into a side chain of the molecular chain (hereinafter also referred to as "modifying monomer"). In terms of a high effect of improving the dispersibility of the filler, the compound (M) preferably contains at least one selected from the group consisting of an initiation terminal modifier and a terminal modifier, and more preferably contains a terminal modifier.

[0018] The conjugated diene polymer contained in the polymer composition P can be produced, for example, by a method including the following polymerization steps. When part or all of the conjugated diene polymer contained in the polymer composition P is a modified conjugated diene polymer (A1), a polymer produced by a method including the following polymerization steps and modification steps can be preferably used as the modified conjugated diene polymer (A1). 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 (A1).

[0019] In the following, a preferred production method for obtaining a conjugated diene polymer will be explained, along with a preferred embodiment of the molecular structure of the conjugated diene polymer.

[0020] <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.

[0021] 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.

[0022] 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.

[0023] 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 polymer composition P. 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.

[0024] 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.

[0025] As a polymerization method for polymerizing a monomer containing a conjugated diene compound, a solution polymerization method is particularly preferred. The polymerization method may be either a batch method or a continuous method. When using a 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). From the viewpoints of improving the processability of the polymer composition, increasing the dispersibility of the filler (particularly silica), obtaining a high-strength crosslinked body, and polymer productivity, a continuous method (specifically, a method in which raw materials are continuously fed into a reactor and a product is continuously withdrawn from the reactor) is preferred.

[0026] In a continuous polymerization system, the raw material supply rate may be constant or variable. Furthermore, as long as the polymerization reaction includes a step of continuously supplying raw materials to a reactor, the polymerization reaction may further include a step of intermittently supplying raw materials. Similarly, in a continuous polymerization system, the product withdrawal rate may be constant or variable. Furthermore, as long as the polymerization reaction includes a step of continuously withdrawing the product from the reactor, the polymerization reaction may further include a step of intermittently withdrawing the product.

[0027] 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.

[0028] 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 specific element derived from the initiation terminal-modifying agent can be introduced into the polymerization initiation terminal of the conjugated diene polymer.

[0029] 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.

[0030] 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."

[0031] 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 improving the processability of polymer composition P and the fuel economy performance of the crosslinked material obtained using polymer composition P in a well-balanced manner, 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 can be used alone, or two or more types can be used in combination.

[0032] In addition, a nitrogen-containing alkali metal compound (hereinafter also referred to as 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.

[0033] 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 constituting the conjugated diene polymer 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.

[0034] 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.

[0035] It is to be noted that 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 7% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. When the vinyl group content is 7% 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.

[0040] <Modification Step> In the modification step, a conjugated diene polymer having an active end is reacted with a compound (M). This reaction causes a polymer chain containing a monomer unit derived from the conjugated diene compound to bond with the compound (M) at the reaction site of the compound (M), thereby producing a modified conjugated diene polymer having a specific element at the polymer end. The conjugated diene polymer having an active end may be either modified or unmodified at the polymerization initiation end.

[0041] As the compound (M), a compound having a specific element and a functional group capable of reacting with the active terminal of the conjugated diene polymer can be preferably used. By using such a compound, an element that contributes greatly to improving the dispersibility of the filler (particularly silica) can be relatively easily introduced into the polymer. The specific element contained in the compound (M) is preferably at least one selected from the group consisting of nitrogen, oxygen, silicon, sulfur, and phosphorus.

[0042] When a blend is obtained using the polymer composition P, a compound having one or more nitrogen-containing groups and one or more hydrocarbyloxysilyl groups in one molecule can be preferably used as the compound (M), in order to further improve the dispersibility of the filler (particularly silica) in the blend. In order to highly contribute to improving the dispersibility of the filler (particularly silica), the nitrogen-containing group is preferably 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.

[0043] 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 (2), 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 (2), A ２ has nitrogen and no active hydrogen, and R １７ is a monovalent functional group bonded to R via nitrogen. １５ and R １６ is a hydrocarbyl group, and R １７ is a hydrocarbylene group, and r is an integer of 0 to 2. When r is 0 or 1, multiple R １６ are the same or different, and when r is 2, multiple R １５ are the same or different.) (In formula (3), A ３ has at least one element selected from the group consisting of nitrogen, phosphorus, oxygen, sulfur, and silicon, does not have active hydrogen, and R ２２R is a monovalent functional group bonded to R via nitrogen, phosphorus, oxygen, sulfur, or silicon, or a hydrocarbyl group having 1 to 20 carbon atoms. ２２ is a single bond or a hydrocarbylene group. ２３ and R ２４ are each independently a hydrocarbyl group. ２５ is a hydrocarbylene group. 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. ３２ and R ３３ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. 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. ３４ is an m-valent hydrocarbon group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms which has at least one element selected from the group consisting of nitrogen, oxygen, and sulfur and does not have 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. 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 ４７are 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.)

[0044] In the above formulas (2) and (3), R １５ , R １６ , R ２３ or 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. １７ or R 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.

[0045] A ２ Nitrogen contained in A ３ At least one element selected from the group consisting of nitrogen, phosphorus, oxygen, sulfur, and silicon contained in A may not be bonded to an active hydrogen and may be protected by a protecting group (for example, a tri-substituted hydrocarbylsilyl group, a hydrocarbyloxysilyl group, or the like). ２ or A ３ may be a group that can be converted into an onium ion by an onium salt generating agent, where the onium salt generating agent is a Bronsted acid or a compound that generates a Bronsted acid upon contact with water.

[0046] A ２ Specific examples of and A ３ A when has nitrogen ２ and A ３Specific examples of A include a nitrogen-containing group in which two hydrogen atoms of a primary amino group are substituted with two protecting groups, a nitrogen-containing group in which one hydrogen atom of a secondary amino group is substituted with one protecting group, a tertiary amino group, an imino group, a pyridyl group, etc. ３ A when containing phosphorus, oxygen, sulfur or silicon ３ Specific examples of the above include a phosphorus-containing group in which two hydrogen atoms of a primary phosphino group are substituted with two protecting groups, a phosphorus-containing group in which one hydrogen atom of a secondary phosphino group is substituted with one protecting group, a tertiary phosphino group, a group in which the hydrogen atom of a hydroxyl group is protected with a protecting group, a sulfur-containing group in which the hydrogen atom of a thiol group is substituted with a protecting group, and a hydrocarbyloxysilyl group.

[0047] A ３ is preferably a group having silicon or nitrogen, and more preferably a hydrocarbyloxysilyl group, a nitrogen-containing group having a protecting group, or a tertiary amino group.

[0048] 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.

[0049] 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.

[0050] R ３４is 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Specific examples of the terminal modifying agent include compounds represented by the above formula (2), such as N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and 3-(4-trimethylsilyl-1-piperazino)propylmethyldimethoxysilane.

[0055] Examples of the compound represented by formula (3) include 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, 1-triethylsilyl-2,2-diethoxy-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2-(2,2-dimethoxy-1,2-azasilolidin-1-yl)-N,N-diethylethane-1-amine, etc. For example, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane 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 the 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-imidazole- Examples of the compound (M) include N-(3-(1H-imidazol-1-yl)propyl)-3-(trimethoxysilyl)-N-(3-(trimethoxysilyl))propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-N,N-bis(3-(trimethoxysilyl))propyl)propanamine, and compounds in which the alkyl group and alkanediyl group in these compounds are replaced with an alkyl group having 1 to 6 carbon atoms and an alkanediyl group having 1 to 6 carbon atoms, respectively. As the compound (M), 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 (A1), 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. Examples of the coupling agent include compounds that contain a specific element, are free of active hydrogen, and have multiple functional groups capable of reacting with the polymerization active terminal. Specific examples of the coupling agent include 2,4-tolylene diisocyanate, diphenylmethane diisocyanate, N,N,N',N'-tetramethylphthalamide, silicon tetrachloride, N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone, and tin tetrachloride. The reaction using the coupling agent may be carried out before or after the reaction between the polymerization active terminal and the terminal-modifying agent, or may be carried out simultaneously with the reaction between the polymerization active terminal and the terminal-modifying agent.

[0062] Alternatively, before the reaction of the polymerization active terminal with the terminal-modifying agent, an aromatic vinyl compound having a trihydrocarbyloxysilyl group bonded to an aromatic ring (hereinafter 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.

[0063] When a compound having a protecting group (such as a trisubstituted hydrocarbylsilyl group) is used as the terminal modifier, the modified conjugated diene polymer (A1) may be obtained by partially or completely replacing the protecting groups of a modified conjugated diene polymer having protecting groups derived from the terminal modifier with hydrogen. Furthermore, when a compound having a protecting group is used as the terminal modifier, the modified conjugated diene polymer (A1) modified with the terminal modifier may be further reacted with an onium salt generating agent. In this case, a polymer having an onium salt structure at the polymer terminal can be obtained as the modified conjugated diene polymer (A1). Having an onium salt structure in the modified conjugated diene polymer (A1) is preferable in that it can improve the shape retention of a crosslinked body obtained using the polymer composition.

[0064] The weight average molecular weight (Mw) of the conjugated diene polymer, as calculated using polystyrene standards by gel permeation chromatography (GPC), is preferably 1.0×10 ５ or more. Mw is 1.0 × 10 ５ When the Mw of the conjugated diene polymer 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 conjugated diene polymer is preferably 4.0 × 10 ６ The Mw of the conjugated diene polymer is 4.0 × 10 or less. ６ When the Mw of the conjugated diene polymer is 2.0×10 or less, the processability of the polymer composition tends to be further improved. ６ More preferably, 1.8 × 10 ６The weight average molecular weight (Mw) of the conjugated diene polymer referred to here is the value (total weight average molecular weight) determined from all peaks of a GPC curve measured by GPC.

[0065] 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 conjugated diene polymer in terms of polystyrene, measured by GPC, is preferably 1.00 to 10.0. When Mw / Mn is 1.00 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 conjugated diene polymer is more preferably 1.10 or more, even more preferably 1.20 or more, and even more preferably 1.60 or more. When Mw / Mn of the conjugated diene polymer is 10.0 or less, good fuel economy and good reinforcing filler dispersibility tend to be achieved during the crosslinked body. The Mw / Mn of the conjugated diene polymer is more preferably 3.00 or less, even more preferably 2.70 or less, even more preferably 2.50 or less, and particularly preferably 2.30 or less.

[0066] The glass transition temperature (Tg) of the conjugated diene polymer is preferably -100°C to 0°C. When the Tg of the conjugated diene polymer is -100°C or higher, the abrasion resistance and strength of the resulting blend tend to be improved. Furthermore, when the Tg of the conjugated diene polymer is 0°C or lower, the fuel economy of the resulting blend tends to be improved. The Tg of the conjugated diene polymer is more preferably -90°C or higher, and even more preferably -80°C or higher. Furthermore, the Tg of the conjugated diene polymer is more preferably -10°C or lower, even more preferably -20°C or lower, even more preferably -30°C or lower, and even more preferably -40°C or lower. The glass transition temperature of the conjugated diene polymer is a value measured in accordance with JIS K6240:2011.

[0067] Of the conjugated diene polymers contained in the polymer composition P, the proportion of the modified conjugated diene polymer (A1) is preferably 30% by mass or more relative to the total amount of the conjugated diene polymers. When the proportion of the modified conjugated diene polymer (A1) is 30% by mass or more, the dispersibility of the filler (particularly silica) in the blend tends to be sufficiently improved. The proportion of the modified conjugated diene polymer (A1) is more preferably 40% by mass or more, even more preferably 50% by mass or more, and even more preferably 70% by mass or more relative to the total amount of the conjugated diene polymers.

[0068] <Component (B): Thermoplastic Resin> The polymer composition P contains a thermoplastic resin (hereinafter also referred to as "thermoplastic resin (B)") having a softening point of 100°C to 150°C. If the softening point of the thermoplastic resin contained in the polymer composition is less than 100°C, the crosslinked body obtained from the polymer composition containing the conjugated diene polymer will have poor handling stability at low temperatures and will not have sufficient fuel economy. If the softening point of the thermoplastic resin contained in the polymer composition exceeds 150°C, the crosslinked body obtained from the polymer composition containing the conjugated diene polymer will tend to have reduced fuel economy.

[0069] From the viewpoint of improving the fuel economy performance and low-temperature handling stability of the crosslinked body obtained from the polymer composition P, the softening point of the thermoplastic resin (B) is preferably 103°C or higher, more preferably 105°C or higher, and even more preferably 110°C or higher. The softening point of the thermoplastic resin (B) is preferably 145°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. In this specification, the softening point of the thermoplastic resin is a value measured in accordance with ASTM D6090.

[0070] The type of main skeleton of the thermoplastic resin (B) is not particularly limited as long as the softening point is within the range of 100 to 150° C. In terms of being able to enhance affinity with the conjugated diene polymer, the thermoplastic resin (B) is preferably at least one selected from the group consisting of a styrene-based resin, polyethylene, a C5-based resin, a C9-based resin, a C5 / C9-based resin, a dicyclopentadiene (DCPD)-based resin, a dicyclopentadiene / C9-based resin, an alkylphenol-based resin, a terpene-based resin, a hydrogenated C5 resin, a hydrogenated C9 resin, a hydrogenated dicyclopentadiene-based resin, a hydrogenated dicyclopentadiene / C9-based resin, and a hydrogenated terpene-based resin.

[0071] 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. Examples of the styrene-based monomer include the same compounds as those exemplified as the aromatic vinyl compounds that may be used as constituent monomers of the conjugated diene-based polymer. The styrene-based monomer constituting the styrene-based resin is preferably at least one selected from the group consisting of styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene, and more preferably one or both of styrene and α-methylstyrene.

[0072] The styrene-based resin may 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 monocarboxylic acids such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate; dienes such as chloroprene, butadiene, and isoprene; olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids or acid anhydrides thereof such as maleic acid and maleic anhydride; and the like.

[0073] The styrene-based resin preferably has structural units derived from styrene-based monomers in an amount of 20% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total amount of monomer units contained in the styrene-based resin.

[0074] 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.

[0075] 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 one or both of 1,3-butadiene and isoprene. The content of the conjugated diene polymer block 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 polymer block is preferably 80% by mass or less, and more preferably 70% by mass or less.

[0076] The content of the polystyrene block in the block polymer is preferably 20% by mass or more, more preferably 30% by mass or more, in order to increase the breaking strength. The content of the polystyrene block is preferably 80% by mass or less, more preferably 70% by mass or less. The respective proportions of the polystyrene block and the conjugated diene polymer block in the block polymer are as follows: １ It can be calculated from the integral ratio of the H-NMR spectrum.

[0077] 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. As the block polymer, SBS or SIS having a conjugated diene polymer block in which the soft segment is not hydrogenated, or an epoxidized styrene-butadiene-styrene block copolymer, which have sufficient crosslinking points, can be preferably used.

[0078] Examples of polyethylene include low-density polyethylene (LDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE).

[0079] C5 resins are produced by subjecting C5 fraction to Friedel-Crafts catalyst (AlCl ３ or BF ３ It 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.

[0080] C9 resins were prepared by subjecting C9 fraction to Friedel-Crafts catalyst (AlCl ３ or BF ３ A solid polymer (C9 synthetic petroleum resin) obtained by polymerization using a methyl indene, methyl indene, coumarone, vinyl toluene, etc. is a specific example of a C9 resin.

[0081] C5 / C9 resins are produced by subjecting C5 to C9 fractions to Friedel-Crafts catalyst (AlCl ３ or BF ３ It is a solid polymer (C5 / C9 synthetic petroleum resin) obtained by polymerization using a vinyl toluene copolymer, ...

[0082] Dicyclopentadiene (DCPD) resins are petroleum resins that use dicyclopentadiene (DCPD) in C5 fractions as the main raw material. Specific examples of dicyclopentadiene resins include the "Marukarets M" series (M-890A, M-845A, etc.) manufactured by Maruzen Petrochemical Co., Ltd.

[0083] Dicyclopentadiene / C9 resin is a petroleum resin made primarily from dicyclopentadiene (DCPD) in the C5 fraction and the C9 fraction. Specific examples of dicyclopentadiene / C9 resins include ENEOS Corporation's product name "EP-140."

[0084] Examples of alkylphenol resins include alkylphenol-acetylene resins such as p-tert-butylphenol-acetylene resin, and alkylphenol-formaldehyde resins with a low degree of polymerization.

[0085] 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.

[0086] A representative example of a terpene-aromatic compound resin is a 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. The terpene-aromatic compound resin used as component (B) is preferably a terpene-phenol resin with a low phenol content. Here, "low phenol content" refers to a phenol 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 component (B) can further improve handling performance. As the terpene-aromatic compound resin, commercially available products can be used, such as those under the trade name "Tamanol 901" (manufactured by Arakawa Chemical Industries, Ltd.) and those under the trade name "SYLVATRAXX4202" (manufactured by Arizona Chemical Co., Ltd.).

[0087] Hydrogenated C5 resin, hydrogenated C9 resin, hydrogenated dicyclopentadiene resin, hydrogenated dicyclopentadiene / C9 resin, and hydrogenated terpene resin (hereinafter collectively referred to as "hydrogenated resins") are resins obtained by hydrogenating raw material resins. When a hydrogenated resin is used as component (B), the softening point of the hydrogenated resin may be any value as long as it is 100°C to 150°C. As the hydrogenated resin, commercially available products can be used. Examples of hydrogenated C5 resins include those sold under the trade name "Impera (registered trademark) E1780" (manufactured by Eastman Co.); examples of hydrogenated C9 resins include those sold under the trade name "Alcon M135" (manufactured by Arakawa Chemical Industries, Ltd.); examples of hydrogenated dicyclopentadiene resins include those sold under the trade name "Oppera PR-120" (manufactured by ExxonMobil Corporation) and "T-REZ HA125" (manufactured by ENEOS Corporation); and examples of hydrogenated dicyclopentadiene / C9 resins include those sold under the trade name "T-REZ PR803" (manufactured by ENEOS Corporation).

[0088] From the viewpoint of affinity with the conjugated diene polymer, the thermoplastic resin (B) is more preferably at least one selected from the group consisting of a C5 resin, a C9 resin, a C5 / C9 resin, a dicyclopentadiene resin, a dicyclopentadiene / C9 resin, a hydrogenated C5 resin, a hydrogenated C9 resin, a hydrogenated dicyclopentadiene resin, and a hydrogenated dicyclopentadiene / C9 resin, and even more preferably at least one selected from the group consisting of a C5 resin, a C9 resin, a C5 / C9 resin, a hydrogenated dicyclopentadiene resin, and a hydrogenated dicyclopentadiene / C9 resin.

[0089] The weight average molecular weight (Mw) of the thermoplastic resin (B) is preferably 400 to 3,000, more preferably 500 to 2,800, and even more preferably 600 to 2,500, from the viewpoint of solubility in organic solvents.

[0090] The content of the thermoplastic resin (B) is 5 to 20 parts by mass relative to 100 parts by mass of the conjugated diene polymer contained in the polymer composition P. If the content of the thermoplastic resin (B) is less than 5 parts by mass, the crosslinked body obtained using the polymer composition tends to have poor handling stability at low temperatures. Furthermore, if the content of the thermoplastic resin (B) exceeds 20 parts by mass, the crosslinked body obtained using the polymer composition tends to have poor fuel economy. From the viewpoint of obtaining a crosslinked body with superior handling stability at low temperatures, the content of the thermoplastic resin (B) is preferably 6 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 9 parts by mass or more, relative to 100 parts by mass of the conjugated diene polymer. Furthermore, from the viewpoint of obtaining a crosslinked body with superior fuel economy, the content of the thermoplastic resin (B) is preferably 19 parts by mass or less, more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or less, relative to 100 parts by mass of the conjugated diene polymer. One type of thermoplastic resin (B) may be used alone, or two or more types may be used in combination.

[0091] <Component (C): Extender Oil> The polymer composition P may contain an oil (extender oil) for oil extension. The extender oil may be a process oil commonly used for extending elastomers. Suitable process oils include various oils known in the art, such as aromatic oils, paraffinic oils, naphthenic oils, vegetable oils (soybean oil, sunflower oil, etc.), and 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.

[0092] When an extender oil is blended into polymer composition P, the content of the extender oil in polymer composition P is preferably 0.05 to 50 parts by mass per 100 parts by mass of the conjugated diene polymer contained in polymer composition P, 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 conjugated diene polymer. Furthermore, the content of the extender oil is more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the conjugated diene polymer.

[0093] The polymer composition P is a composition containing a conjugated diene polymer and a thermoplastic resin (thermoplastic resin (B)) having a softening point of 100 to 150°C, and containing an extender oil as an optional component. Since the extender oil is an optional component, the content of the extender oil in the polymer composition P may be 0% by mass. The polymer composition P may further contain a component different from the components (A) to (C). Examples of the component different from the components (A) to (C) include an antioxidant.

[0094] In the polymer composition P, the total amount of the conjugated diene polymer, the thermoplastic resin (B), and the extender oil is 90% by mass or more of the entire composition. In the polymer composition P, the total amount of the conjugated diene polymer, the thermoplastic resin (B), and the extender oil is preferably 92% by mass or more, and more preferably 93% by mass or more, based on the total amount of the polymer composition P. One embodiment of the polymer composition P is a solid from which the solvent has been removed. The polymer composition P 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 (for example, a rectangular parallelepiped).

[0095] <<Method for Producing Polymer Composition>> The polymer composition P is preferably produced by a method including the following mixing step and desolvation step. Mixing step: a step of mixing a conjugated diene polymer and a thermoplastic resin (B) in an organic solvent in a ratio of 5 to 20 parts by mass of the thermoplastic resin (B) per 100 parts by mass of the conjugated diene polymer to obtain a mixture. Desolvation step: a step of removing the solvent from the mixed liquid obtained in the mixing step (hereinafter also referred to as "mixed liquid SC") Each step will be described in detail below.

[0096] <Mixing Step> In the mixing step, the conjugated diene polymer and the thermoplastic resin (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 monomer. 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.

[0097] From the viewpoint of increasing the dispersibility of the thermoplastic resin (B) in the polymer composition P and sufficiently improving the handling stability and fuel economy performance of the polymer composition P at low temperatures, it is preferable that in the mixing step, a polymer solution in which a conjugated diene-based polymer is dissolved in an organic solvent (hereinafter also referred to as "polymer solution SA") is mixed with the thermoplastic resin (B).

[0098] The polymer solution SA may be a polymer solution obtained during the production of a conjugated diene polymer (preferably a polymer solution obtained by solution polymerization) as is, or a solution prepared by dissolving an isolated conjugated diene polymer in an appropriate solvent. From the viewpoint of improving the dispersibility of a filler (particularly silica) when the polymer composition P is mixed with a filler to prepare a blend, a polymer solution containing a modified conjugated diene polymer (A1) is preferably used as the polymer solution SA. As the polymer solution containing the modified conjugated diene polymer (A1), a reaction solution containing the modified conjugated diene polymer (A1) obtained by the process including the polymerization step and the modification step described above may be used as is, or a solution prepared by isolating the modified conjugated diene polymer (A1) 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 (A1) obtained by the modification step described above as the polymer solution SA, since this reduces the number of steps and increases productivity. The details of the polymerization step and the modification step are the same as those described above.

[0099] The content of the conjugated diene polymer 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, relative to the total amount of the polymer solution SA. Furthermore, the content of the conjugated diene polymer 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 making the content of the conjugated diene polymer in the polymer solution SA 1% by mass or more, a sufficient production amount of the polymer composition P can be ensured during the production of the polymer composition P. Furthermore, by making the content of the conjugated diene polymer in the polymer solution SA 90% by mass or less, the thermoplastic resin (B) can be uniformly dispersed in the polymer solution SA.

[0100] The manner in which the conjugated diene polymer and the thermoplastic resin (B) are mixed is not particularly limited. For example, when the thermoplastic resin (B) is added to a polymer solution SA containing a conjugated diene polymer, the thermoplastic resin (B) may be added to the polymer solution SA all at once, in portions, or continuously. When the thermoplastic resin (B) is added to the polymer solution SA, the thermoplastic resin (B) may be added as a solid, or the solid thermoplastic resin (B) may be dissolved in an organic solvent capable of dissolving the thermoplastic resin (B), and the resulting resin solution may be added to the polymer solution SA. In order to efficiently disperse the thermoplastic resin (B) in the polymer solution SA, the thermoplastic resin (B) is preferably added to the polymer solution SA in a state dissolved in an organic solvent capable of dissolving the thermoplastic resin. Examples of the organic solvent include the organic solvents used in the polymerization of the conjugated diene polymer and the compounds exemplified in the description of the vinyl group content adjuster (randomizer).

[0101] After adding the thermoplastic resin (B) to the polymer solution SA, it is advisable to carry out a process such as stirring to uniformly disperse the thermoplastic resin (B) in the polymer solution SA. The temperature when mixing the polymer solution SA and the thermoplastic resin (B) is the same as the temperature of the polymerization reaction, preferably −20° C. to 150° C., more preferably 0 to 120° C., and even more preferably 20 to 100° C.

[0102] When an extender oil is blended into the polymer composition P, the method for adding the extender oil is not particularly limited. For example, the extender oil may be added to a polymer solution containing the conjugated diene-based polymer after polymerization, and then removed in a subsequent desolvation step to be blended as an oil-extended rubber. In this case, the extender oil may be added before the thermoplastic resin (B) is added to the polymer solution, or may be added after the thermoplastic resin (B) is added to the polymer solution.

[0103] When mixing the conjugated diene polymer and the thermoplastic resin (B), it is preferable to adjust the amount of the thermoplastic resin (B) to 5 to 20 parts by mass per 100 parts by mass of the conjugated diene polymer. By adjusting the mixing ratio of the thermoplastic resin (B) within the above range, it is possible to improve the fuel economy performance and low-temperature handling stability of the crosslinked body obtained from the polymer composition P in a well-balanced manner. From this viewpoint, the mixing ratio of the thermoplastic resin (B) is preferably 6 parts by mass or more, more preferably 7 parts by mass or more, and even more preferably 9 parts by mass or more per 100 parts by mass of the conjugated diene polymer. Furthermore, the mixing ratio of the thermoplastic resin (B) is preferably 19 parts by mass or less, more preferably 17 parts by mass or less, and even more preferably 15 parts by mass or less per 100 parts by mass of the conjugated diene polymer.

[0104] <Solvent Removal Step> In the solvent removal step, the solvent is removed from the mixed liquid SC obtained in the mixing step to isolate a polymer composition (i.e., polymer composition P). The method for removing the solvent from the mixed liquid SC is not particularly limited. For example, the solvent can be removed from the mixed liquid SC by known solvent removal methods such as a method of separating the solvent by steam stripping and dehydrating and drying the obtained 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.

[0105] 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 conjugated diene polymer and the thermoplastic resin (B).

[0106] <<Blend>> The blend of the present disclosure (hereinafter also referred to as “blend Q”) is a composition obtained by blending the above-described polymer composition P of the present disclosure and a filler (referred to as component (D)).

[0107] <Component (D): 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 (6) (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...(6) (In formula (6), M ２ is at least one selected from the group consisting of a specific metal, which is any one of aluminum, magnesium, titanium, calcium, and zirconium, 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 10, and i is an integer of 0 to 10.

[0108] Examples of silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among these, wet silica is particularly preferred from the viewpoint of improving fracture properties and achieving both wet grip and low rolling resistance. In addition, the use of high dispersible type silica is also preferred from the viewpoint of improving dispersibility in the compound Q and improving physical properties and processability. Note that one type of silica can be used alone or two or more types can be used in combination.

[0109] The amount of silica used in Compound Q (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 amount of the rubber components contained in Compound Q.

[0110] 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. In this specification, the rubber component (hereinafter also referred to as "compounded rubber component") that is blended separately from the conjugated diene polymer in polymer composition P when compound Q is produced by mixing (more specifically, kneading) the conjugated diene polymer, polymer composition P, and a filler is collectively referred to simply as "rubber component."

[0111] Examples of carbon black include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, etc. The proportion of carbon black used in this compound (the total amount when two or more types are contained) is preferably 1 to 80 parts by mass, more preferably 2 to 70 parts by mass, even more preferably 3 to 50 parts, and particularly preferably 4 to 30 parts by mass, per 100 parts by mass of the total amount of the rubber components contained in Compound Q.

[0112] In addition to silica and carbon black as inorganic fillers, various reinforcing fillers such as clay and calcium carbonate may be further blended into the compound Q. 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 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 silicate, calcium magnesium silicate (CaMgSiO ４), talc, etc.; compounds in which the specific metal is titanium include, for example, titanium oxide, etc.; compounds in which the specific metal is calcium include, for example, calcium oxide, calcium hydroxide, calcium silicate, calcium carbonate, etc.; and compounds in which the specific metal is zirconium include, for example, zirconium oxide, zirconium hydroxide, zirconium silicate, zirconium carbonate, etc.

[0113] 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 a conjugated diene polymer, it is preferable that compound Q contains silica as a filler, and it is preferable to use wet silica, dry silica, or colloidal silica.

[0114] The content of the filler in the present compound (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 compound.

[0115] <Other Components> Blend Q may further contain components (hereinafter also referred to as "other components") other than the polymer composition and filler of the present disclosure described above, as long as the effects of the present disclosure are not impaired. Below, other components that can be contained in Blend Q will be described.

[0116] Component (E): Compounded Rubber Component In addition to the conjugated diene polymer contained in polymer composition P, a rubber component (compounded rubber component) may be further added to compound Q when producing compound Q. The type of compounded rubber component is not particularly limited. The compounded rubber component may be a conjugated diene polymer, or may be different from the conjugated diene polymer. Furthermore, when the compounded rubber component is a conjugated diene polymer, the compounded rubber component may be the same as or different from the conjugated diene polymer contained in polymer composition P. From the viewpoint of improving handling stability at low temperatures while ensuring good fuel economy performance, the compounded rubber component is preferably an unmodified rubber, 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, and hydrogenated styrene-butadiene rubber. As the compounded rubber component, one type may be used alone, or two or more types may be used in combination.

[0117] The amount of the compounded rubber component is preferably 5 to 70 parts by mass, more preferably 10 to 60 parts by mass, per 100 parts by mass of the total amount of the rubber components contained in the compound Q (i.e., the total amount of the conjugated diene polymer in the polymer composition P and the amount of the compounded rubber component).

[0118] Component (F): Crosslinking Agent A crosslinking agent is usually compounded into Compound Q. Examples of crosslinking agents include sulfur, sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having methylol groups, with sulfur usually being used. The amount of sulfur compounded 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 amount of the rubber components contained in Compound Q.

[0119] Component (G): Blended Resin When blend Q is produced by mixing polymer composition P and a filler, a thermoplastic or thermosetting resin (hereinafter also referred to as "blended resin") may be blended into blend Q in addition to the thermoplastic resin in polymer composition P. The blended resin is kneaded together with solid polymer composition P and other components added as necessary during the production of the blend.

[0120] The type of blended resin is not particularly limited. The blended resin may be the thermoplastic resin (B) or may be different from the thermoplastic resin (B). Furthermore, when the blended resin is the thermoplastic resin (B), the blended resin may be the same as or different from the thermoplastic resin (B) contained in the polymer composition P.

[0121] From the viewpoint of obtaining a crosslinked product (vulcanized rubber) excellent in various properties such as strength, abrasion resistance, and crack growth resistance, the compounded resin is preferably at least one selected from the group consisting of styrene resins, polyethylene, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene resins, dicyclopentadiene / C9 resins, alkylphenol resins, terpene resins, hydrogenated C5 resins, hydrogenated C9 resins, hydrogenated dicyclopentadiene resins, hydrogenated dicyclopentadiene / C9 resins, and hydrogenated terpene resins. One compounded resin may be used alone, or two or more compounds may be used in combination.

[0122] The blending amount of the blended resin is preferably 1 part by mass or more relative to 100 parts by mass of the rubber component contained in Blend Q. Blending 1 part by mass or more of the blended resin is preferable because the abrasion resistance, breaking strength, and crack growth resistance can be improved in the crosslinked product obtained using Blend Q. The blending amount of the blended resin is more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component contained in Blend Q. Furthermore, from the viewpoint of maintaining various performance properties of Blend Q well, the blending amount of the blended resin is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, and still more preferably 20 parts by mass or less, relative to 100 parts by mass of the rubber component contained in Blend Q.

[0123] In the blend Q, the total amount of the thermoplastic resin (B) contained in the polymer composition P and the compounded resin added during the production of the blend Q is preferably 6 parts by mass or more relative to the rubber component contained in the blend Q. By setting the total amount of the thermoplastic resin (B) and the compounded resin in the blend Q within the above range, the effect of improving the abrasion resistance of the crosslinked product obtained using the blend Q can be sufficiently enhanced, which is preferable. The total amount of the thermoplastic resin (B) and the compounded resin in the blend Q is more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the rubber component in the blend Q. Furthermore, from the viewpoint of maintaining the various performance properties of the blend Q well, the total amount of the thermoplastic resin (B) and the compounded resin in the blend Q is preferably 120 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 25 parts by mass or less, relative to 100 parts by mass of the rubber component contained in the blend Q.

[0124] Component (H): Silane Coupling Agent When silica is contained in Compound Q, the reinforcing properties of the silica can be further enhanced by including a silane coupling agent in Compound Q together with the silica. 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, and (3-[ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol.

[0125] The amount of the silane coupling agent is preferably 1 to 20 parts by mass per 100 parts by mass of silica. By setting the amount of the silane coupling agent to 1 part by mass or more, the effect of improving the dispersibility of silica can be sufficiently obtained. Furthermore, by setting the amount of the silane coupling agent to 20 parts by mass or less, it is possible to suppress a decrease in the processability of Compound Q and to suppress a decrease in the elongation at break of the crosslinked body obtained from Compound Q. The amount of the silane coupling agent is more preferably 5 to 15 parts by mass per 100 parts by mass of silica. Only one type of silane coupling agent may be used, or two or more types may be used in combination.

[0126] Component (I): Blended Extender Oil When blend Q is produced by mixing polymer composition P and a filler, an extender oil (hereinafter also referred to as "blend extender oil") may be blended into blend Q as an oil for oil extension. Examples of blended extender oils include process oils that are generally used to oil-extend elastomers, and specifically, the same extender oils as those exemplified in the description of component (C) can be used. When polymer composition P contains an extender oil, the blended extender oil may be the same as or different from the extender oil contained in polymer composition P. As blended extender oils, one type may be used alone, or two or more types may be used in combination.

[0127] The method for adding the compounding extender oil is not particularly limited. For example, there is a method in which the compounding extender oil is directly added during kneading to obtain a rubber compound, which is one form of compound Q, thereby compounding the compounding extender oil into compound Q. The compounding amount of the compounding extender oil is preferably 0.05 to 100 parts by mass per 100 parts by mass of the total amount of the rubber components contained in compound Q.

[0128] In addition to the components described above, Compound Q can 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, vulcanization accelerators, compatibilizers, vulcanization aids, processing aids, and scorch inhibitors. The amounts of these additives can be appropriately selected depending on the various components, as long as they do not impair the effects of the present disclosure.

[0129] A filler and, if necessary, the various components described above can be blended with the polymer composition P to obtain the compound Q. Specifically, the compound Q can be obtained by mixing the polymer composition P with the filler and various additives that are optionally used in compounds 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).

[0130] <<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.

[0131] - Kneading Step In the kneading step, first, the polymer composition P described above, the filler, 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 kneading temperature in the first step can be appropriately set so that the polymer composition P, the filler, and the first additive are sufficiently melt-kneaded. This melt-kneading allows the filler and the first additive to be mixed with the polymer composition P, thereby sufficiently achieving effects such as increasing the strength of the rubber product after vulcanization, improving the kneading processability of the polymer composition P, and preventing rubber degradation due to radicals generated during kneading.

[0132] Next, the kneaded product obtained in the first step is returned to room temperature as necessary, and then vulcanization-related compounding agents are added to the kneaded product, followed by melt-kneading using a kneader (second step). The compound Q obtained in the second step is molded and processed, and then crosslinked (vulcanized) to obtain a crosslinked product.

[0133] <Crosslinked Product and Tire> The crosslinked product obtained using the polymer composition P can be applied 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 skin materials for various vehicles such as automobiles, ships, aircraft, and railways; building materials; vibration-proof rubbers for industrial machinery and equipment; various hoses and hose covers such as diaphragms, rolls, 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.

[0134] A crosslinked product having excellent fuel economy and handling stability at low temperatures can be obtained from the polymer composition P. Therefore, the polymer composition P is particularly suitable as a material for one or both of the tread and sidewall of a tire.

[0135] Incidentally, the reason why a crosslinked body excellent in fuel economy and handling stability at low temperatures can be obtained by producing a crosslinked body using polymer composition P is not clear. However, one hypothesis is that a conjugated diene polymer and a thermoplastic resin having a relatively high softening point of 100 to 150°C are mixed in advance (preferably in an organic solvent), and a filler or the like is blended into the polymer composition P thus obtained to produce blend Q. This makes it possible to homogenize the conjugated diene polymer and the thermoplastic resin having a softening point of 100 to 150°C in blend Q, and thus makes it possible to obtain a crosslinked body excellent in fuel economy and handling stability at low temperatures.

[0136] 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.

[0137] According to the present disclosure described above, the following means are provided. [Means 1] A polymer composition containing a conjugated diene polymer and a thermoplastic resin, and optionally containing an extender oil, wherein the thermoplastic resin has a softening point of 100 to 150°C, the content of the thermoplastic resin is 5 to 20 parts by mass relative to 100 parts by mass of the conjugated diene polymer, the content of the extender oil is 0 to 50 parts by mass relative to 100 parts by mass of the conjugated diene polymer, and the total amount of the conjugated diene polymer, the thermoplastic resin, and the extender oil is 90% by mass or more of the total composition. [Means 2] The polymer composition of [Means 1], wherein the conjugated diene polymer contains a modified conjugated diene polymer (A1), and the modified conjugated diene polymer (A1) has at least one element selected from the group consisting of nitrogen, oxygen, silicon, sulfur, phosphorus, and tin. [Means 3] The polymer composition of [Means 2], wherein a proportion of the modified conjugated diene polymer (A1) is 30 mass% or more based on the total amount of the conjugated diene polymer. [Means 4] The polymer composition of any of [Means 1] to [Means 3], wherein the weight average molecular weight of the conjugated diene polymer is 100,000 to 4,000,000. [Means 5] The polymer composition of any of [Means 1] to [Means 4], wherein the molecular weight distribution Mw / Mn, defined as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn of the conjugated diene polymer, is 1.00 to 10.0. [Means 6] The polymer composition of any one of [Means 1] to [Means 5], wherein the thermoplastic resin is at least one selected from the group consisting of a styrene-based resin, polyethylene, a C5-based resin, a C9-based resin, a C5 / C9-based resin, a dicyclopentadiene-based resin, a dicyclopentadiene / C9-based resin, an alkylphenol-based resin, a terpene-based resin, a hydrogenated C5 resin, a hydrogenated C9 resin, a hydrogenated dicyclopentadiene-based resin, a hydrogenated dicyclopentadiene / C9-based resin, and a hydrogenated terpene-based resin. [Means 7] The polymer composition of any one of [Means 1] to [Means 3], wherein the conjugated diene-based polymer has a glass transition temperature of -100°C to 0°C. [Means 8] A blend obtained by blending the polymer composition of any one of [Means 1] to [Means 7] with a filler. [Means 9] The blend of [Means 8], further containing a crosslinking agent. [Means 10] A crosslinked body obtained by crosslinking the compound according to [Means 8] or [Means 9].[Means 11] A tire having a tread, a sidewall, or both, wherein the tread, the sidewall, or both are made using the blend of [Means 8] or [Means 9]. [Means 12] A method for producing a polymer composition, comprising: a step of mixing a conjugated diene polymer and a thermoplastic resin in an organic solvent in a ratio of 5 to 20 parts by mass of the thermoplastic resin to 100 parts by mass of the conjugated diene polymer to obtain a mixture; and a step of removing the solvent from the mixture, wherein the thermoplastic resin has a softening point of 100°C to 150°C.

[0138] The present invention will be described in detail below based on examples, but is not limited to the following 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 are shown below.

[0139] Bound styrene content (%): Using deuterated chloroform as a solvent, １ Calculated by H-NMR measurement. Vinyl group content (%): 400 MHz １ Calculations 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

[0140] Glass transition temperature (Tg): The glass transition temperature was determined from the inflection point of the DSC curve in the range of -100°C to 40°C in accordance with JIS K6240:2011. Specific conditions for measuring the glass transition temperature are as follows: (DSC measurement conditions) Measuring device: Q1000 Differential Scanning Calorimeter (DSC) (manufactured by TA Instruments) Heating rate: 10°C / min Softening point of resin: Measured in accordance with ASTM D6090.

[0141] 1. Synthesis of Modified Conjugated Diene Polymer and Preparation of Polymer Composition P [Example 1: Synthesis of Modified Conjugated Diene Polymer A1-1 and Preparation of Polymer Composition P-1] 2,500 g of cyclohexane, 2.0 mL of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 125 g of styrene and 375 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 30°C, 0.44 g of n-butyllithium as a polymerization initiator was added to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 90°C. After the polymerization conversion reached 99% (35 minutes after the start of polymerization), 2.08 g of 3-(N,N-bistrimethylsilyl)aminopropylmethyldiethoxysilane as a terminal modifier was added and stirred for 10 minutes to obtain a polymer solution containing modified conjugated diene polymer A1-1 (referred to as polymer solution SA1). To the stirred polymer solution SA1, 4.40 g of 2,6-di-tert-butyl-p-cresol was added as an antioxidant, and then 25.0 g of a C5 resin (manufactured by ENEOS Corporation, product name "RC115") was added as a thermoplastic resin to obtain a mixed solution (referred to as mixed solution SC1). The mixed solution SC1 was subjected to steam stripping to remove the solvent, and then dried using a heated roll adjusted to 130°C, thereby obtaining a polymer composition P-1 containing the modified conjugated diene polymer A1-1 and the C5 resin.

[0142] Various physical property values ​​of the modified conjugated diene polymer A1-1 are shown in Table 1. The physical properties of the modified conjugated diene polymer A1-1 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.

[0143] [Examples 2, 3, 5 to 7, 10 to 12, Comparative Examples 1 to 3] Modified conjugated diene polymers A1-2, A1-3, A1-5 to A1-7, and A1-10 to A1-15, and polymer compositions P-2, P-3, P-5 to P-7, and P-10 to P-15 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 Table 1. The resin solution was added after the addition of 2,6-di-tert-butyl-p-cresol. Various physical property values ​​of the modified conjugated diene polymers A1-2, A1-3, A1-5 to A1-7, and A1-10 to A1-15 are shown in Table 1.

[0144] In Comparative Example 3, instead of the thermoplastic resin (component (B)) having a softening point of 100 to 150 ° C., 190 g (addition amount of resin: 95 g) of a cyclohexane solution (thermoplastic resin concentration in the cyclohexane solution = 50 mass%) containing thermoplastic resin (b-6) having a softening point of 88 ° C. was added. After adding 2,6-di-tert-butyl-p-cresol, this was added to the polymer solution (SA15) containing the modified conjugated diene polymer A1-15 to obtain a mixed solution SC15, and then the solvent was removed by steam stripping to obtain a polymer composition P-15. In Examples 2, 3, 5 to 7, 10 to 12 and Comparative Examples 1 and 2, a resin solution was prepared by dissolving a thermoplastic resin in a solvent, and the resin solution was added to the polymer solution. The solvents used in preparing the resin solutions are shown in Table 1. In Table 1, "resin solution concentration" represents the concentration of the resin solution added to the polymer solution, and "resin solution added amount" represents the amount of resin solution added to the polymer solution. The compositions of the polymer compositions produced in each of the Examples and Comparative Examples are also shown in Table 1. The numerical values ​​of the components in Table 1 are values ​​calculated from the blending amounts (the same applies to Table 2).

[0145] Example 9: Synthesis of modified conjugated diene polymer A1-9 and production of polymer composition P-9 A nitrogen-purged 5-liter autoclave reactor was charged with 2,500 g of cyclohexane, 2.0 mL of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 125 g of styrene and 375 g of 1,3-butadiene as monomers. The temperature of the reactor contents was adjusted to 30°C, and then 0.44 g of n-butyllithium as a polymerization initiator was added to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 90°C. After the polymerization conversion reached 99% (35 minutes after the start of polymerization), 2.08 g of 3-(N,N-bistrimethylsilyl)aminopropylmethyldiethoxysilane as a terminal modifier was added and stirred for 10 minutes to obtain a polymer solution containing modified conjugated diene polymer A1-9 (referred to as polymer solution SA9). To the stirred polymer solution SA9, 4.40 g of 2,6-di-tert-butyl-p-cresol as an antioxidant and 125 g of extender oil (T-DAE, manufactured by ENEOS Corporation) were added and stirred, and then 190 g of a cyclohexane solution (50% by mass) containing a C5 resin (manufactured by ENEOS Corporation, trade name "RC115") as a thermoplastic resin was added to obtain a mixed solution (referred to as mixed solution SC9). The solvent was removed from mixed solution SC9 by steam stripping, and the mixture was dried using a heated roll adjusted to 130°C, thereby obtaining a polymer composition P-9 containing a modified conjugated diene polymer A1-9, extender oil (T-DAE), and a C5 resin.

[0146] Example 4 Synthesis of Modified Conjugated Diene Polymer A1-4 and Production of Polymer Composition P-4 A 50-liter reactor (first reactor) was continuously charged with 58 g / min of 1,3-butadiene as monomers, 17 g / min of styrene, 750 g / min of cyclohexane as a solvent, 0.57 g / min of tetrahydrofuran as a vinyl group content adjuster (randomizer), and 0.031 g / min of n-butyllithium as a polymerization initiator, and the temperature inside the reactor was controlled at 70° C. The polymer solution was continuously decharged from the first reactor at a rate of 825.6 g / min, and 8 g / min of 1,3-butadiene was continuously introduced into the decharged polymer solution in the second reactor, and the reaction was carried out. 1,1′-(1,4-phenylene)bis(N-(3-(triethoxysilyl)propyl)methanimine) was continuously charged at the outlet of the third reactor at a rate of 0.062 g / min, and subsequently di-tert-butyl-p-cresol was added in an amount of 0.88 parts by mass relative to 100 parts by mass of the polymer, to obtain a polymer solution containing modified conjugated diene polymer A1-4 (referred to as polymer solution SA4). Subsequently, a cyclohexane solution containing a C9 resin (manufactured by ENEOS Corporation, trade name "NP140") and a C5 / C9 resin (manufactured by ENEOS Corporation, trade name "RD104") in a mass ratio of 1:1 (thermoplastic resin concentration in the cyclohexane solution = 20 wt% (containing 10 wt% each of the C9 resin and the C5 / C9 resin)) was added to the polymer solution SA4 at a rate of 41.7 g / min to obtain a mixed solution (referred to as mixed solution SC4). Next, the mixed solution SC4 was subjected to steam stripping to remove the solvent, and the mixture was dried using a heated roll adjusted to 130°C, thereby obtaining a polymer composition P-4 containing the modified conjugated diene polymer A1-4, the C9 resin, and the C5 / C9 resin.

[0147] Various physical property values ​​of the modified conjugated diene polymer A1-4 are shown in Table 2. The physical properties of the modified conjugated diene polymer A1-4 were measured using a polymer sample obtained by extracting a portion of the polymer solution SA4 and removing the solvent under conditions of 60°C and 0.1 mmHg for 24 hours.

[0148] Example 8 Polymerization, desolvation, and drying were carried out in the same manner as in Example 4, except that the types and amounts of raw materials used were as shown in Table 2, to obtain a modified conjugated diene polymer A1-8 and a polymer composition P-8. The extender oil was added after the addition of di-tert-butyl-p-cresol and before the addition of the thermoplastic resin. The various physical properties of the modified conjugated diene polymer A1-8 are shown in Table 2.

[0149]

[0150]

[0151] The abbreviations in Tables 1 and 2 are as follows: (Thermoplastic resins) b-1: RC115 (ENEOS Corporation, C5 resin, softening point 113°C, Mw = 2070) b-2: NP140 (ENEOS Corporation, C9 resin, softening point 143°C, Mw = 2100) b-3: RD104 (ENEOS Corporation, C5 / C9 resin, softening point 103°C, Mw = 2460) b-4: HA125 (ENEOS Corporation, hydrogenated DCPD resin, softening point 125°C, Mw = 610) b-5: PR803 (ENEOS Corporation, hydrogenated DCPD / C9 resin, softening point 103°C, Mw = 720) b-6: PR802 (ENEOS Corporation, C5 / C9 resin, softening point 88°C, Mw = 1370) b-7: EP140 (ENEOS Corporation, DCPD / C9 resin, softening point 140°C, Mw = 1320) b-8: V-120S (Nitto Chemical Co., Ltd., coumarone-indene resin, softening point 120°C, Mw = 950) b-9: SYLVATRAXX4202 (Arizona Chemical Co., Ltd., terpene-phenol resin, softening point 115°C) b-10: Cholecin (BASF Corporation, butylphenol-acetylene resin, softening point 143°C)

[0152] 2. Preparation of Compound Q [Examples 13-24, Comparative Examples 4-7] Compound Q was prepared by blending the components according to the formulation shown in Table 3 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, in the first stage of kneading, the temperature was adjusted to 100°C, the rotation speed was 60 rpm, and the kneading time was 4 minutes. Polymer composition P, butadiene rubber (compounded rubber component), resin (compounded resin), silica, carbon black, silane coupling agent, extender oil (compounded extender oil), stearic acid, zinc oxide, and antioxidant were blended and kneaded. Note that the compounded rubber component, compounded resin, and compounded extender oil in Table 3 are components used in the preparation of Compound Q, separate from the conjugated diene polymer, thermoplastic resin, and extender oil contained in polymer composition P. In Examples 16 and 20, butadiene rubber and natural rubber were used in combination as the compounded rubber components. In Comparative Example 7, modified conjugated diene polymer A1-3 was blended in place of polymer composition P. The temperature of the kneaded material discharged from the mixer was around 150°C. Next, in the second stage of kneading, the kneaded material obtained in the first stage of kneading was cooled to room temperature, and then a vulcanization accelerator and sulfur were blended into the mixer. The set temperature was adjusted to 70°C, and kneading was performed under conditions of a rotation speed of 60 rpm and a kneading time of 1.5 minutes to obtain each of Compounds Q (Q-1 to Q-16). The temperature of the kneaded material discharged from the mixer was 100°C or lower when it was discharged. Next, each of the obtained Compounds Q was vulcanized and molded in a vulcanization press at 160°C for a predetermined time to obtain a vulcanized rubber as a crosslinked product. The obtained vulcanized rubbers were evaluated for the following physical properties. The results are shown in Table 3.

[0153] [Compound properties] Loss tangent (3% tan δ (60°C) rolling resistance) Using a vulcanized rubber as a measurement sample, the ratio of the loss modulus G'' to the storage modulus G' (60°C tan δ) was measured using a shear-type dynamic spectrometer (manufactured by TA Instruments) at an angular velocity of 100 radians per second, a temperature of 60°C, and a shear strain of 3%. The ratio is expressed as an index, with the value of Example 13 being set to 100. A larger value indicates lower rolling resistance and better fuel economy.

[0154] Handling stability at low temperatures (G'(-20°C)) Using a vulcanized rubber as a measurement sample, the storage modulus (G'(-20°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 -20°C. The measurement results are expressed as an index, with the value for Example 13 set to 100. A larger value indicates better handling stability at low temperatures.

[0155]

[0156] Details of each component in Table 3 are as follows: *1) Manufactured by ENEOS Materials, trade name "BR01" *2) b-1 to b-10: Same as the explanation of abbreviations in Tables 1 and 2 *3) Silica 1: Manufactured by Solvay, trade name "ZEOSIL 1165MP", Silica 2: Manufactured by Solvay, trade name "ZEOSIL 1115MP" *4) Manufactured by Mitsubishi Chemical Corporation, trade name "Diablack N330" *5) Manufactured by Evonik, trade name "Si75" *6) Process oil T-DAE manufactured by ENEOS Corporation *7) Manufactured by Seiko Chemical Co., Ltd., trade name "Ozonone 6C" *8) Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Noccelaer D" *9) Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Noccelaer DZ-G"

[0157] As can be seen from the results in Table 3, the vulcanized rubber produced from polymer composition P-1 (Example 13) showed significantly improved handling stability at low temperatures compared to the vulcanized rubber of Comparative Example 7, in which the conjugated diene polymer and thermoplastic resin (B) were not mixed in advance in an organic solution, but the thermoplastic resin was simply added during kneading. In contrast, the vulcanized rubber of Comparative Example 4, in which the thermoplastic resin (B) was mixed in an organic solvent during the production of polymer composition P, but the amount of thermoplastic resin (B) added during mixing in the organic solvent was too small, showed significantly worse handling stability at low temperatures compared to the vulcanized rubber of Example 13. Furthermore, the vulcanized rubber of Comparative Example 5, in which the amount of thermoplastic resin (B) added during the production of polymer composition P was too large, showed reduced fuel economy compared to the vulcanized rubber of Example 13. Furthermore, in the vulcanized rubber of Comparative Example 6, in which a thermoplastic resin having a softening point of 88°C was used as the thermoplastic resin used in producing the polymer composition P instead of the thermoplastic resin having a softening point of 100 to 150°C (thermoplastic resin (B)), both fuel economy and handling stability at low temperatures were worse than those of the vulcanized rubber of Example 13.

[0158] Furthermore, the vulcanized rubbers of Examples 14 to 24 produced from the polymer compositions of Examples 2 to 12 also showed well-balanced improvements in low-temperature handling stability and fuel economy compared to the vulcanized rubbers of Comparative Examples 4 to 7.

[0159] From the above results, it was found that a crosslinked body having excellent fuel economy and handling stability at low temperatures can be obtained by producing a crosslinked body using a polymer composition (rubber bale, crumb) which contains a predetermined amount of a thermoplastic resin (thermoplastic resin (B)) having a softening point of 100 to 150°C relative to 100 parts by mass of a conjugated diene polymer, and in which the total amount of the conjugated diene polymer, thermoplastic resin (B) and extender oil is 90% by mass or more of the total composition.

Claims

1. A polymer composition comprising a conjugated diene polymer and a thermoplastic resin, and optionally containing an extender oil, wherein the softening point of the thermoplastic resin is 100 to 150°C, the content of the thermoplastic resin is 5 to 20 parts by mass per 100 parts by mass of the conjugated diene polymer, the content of the extender oil is 0 to 50 parts by mass per 100 parts by mass of the conjugated diene polymer, and the total amount of the conjugated diene polymer, the thermoplastic resin and the extender oil is 90% by mass or more of the entire composition.

2. The polymer composition according to claim 1, wherein the conjugated diene polymer comprises a modified conjugated diene polymer (A1), and the modified conjugated diene polymer (A1) has at least one element selected from the group consisting of nitrogen, oxygen, silicon, sulfur, phosphorus and tin.

3. The polymer composition according to claim 2, wherein the proportion of the modified conjugated diene polymer (A1) is 30 mass % or more based on the total amount of the conjugated diene polymer.

4. The polymer composition according to any one of claims 1 to 3, wherein the conjugated diene polymer has a weight average molecular weight of 100,000 to 4,000,000.

5. The polymer composition according to any one of claims 1 to 3, wherein the molecular weight distribution Mw / Mn, defined as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn of the conjugated diene polymer, is 1.00 to 10.

0.

6. The polymer composition according to any one of claims 1 to 3, wherein the thermoplastic resin is 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, hydrogenated C5 resins, hydrogenated C9 resins, hydrogenated dicyclopentadiene-based resins, hydrogenated dicyclopentadiene / C9 resins, and hydrogenated terpene-based resins.

7. The polymer composition according to any one of claims 1 to 3, wherein the glass transition temperature of the conjugated diene polymer is -100°C to 0°C.

8. A blend comprising the polymer composition according to any one of claims 1 to 3 and a filler.

9. The formulation of claim 8 further comprising a crosslinking agent.

10. A crosslinked product obtained by crosslinking the blend according to claim 8.

11. A tire having a tread, a sidewall, or both, wherein the tread, the sidewall, or both are made with a compound according to claim 8.

12. A method for producing a polymer composition, comprising: a step of mixing a conjugated diene polymer and a thermoplastic resin in an organic solvent in a ratio of 5 to 20 parts by mass of the thermoplastic resin per 100 parts by mass of the conjugated diene polymer to obtain a mixture; and a step of removing the solvent from the mixture, wherein the thermoplastic resin has a softening point of 100°C to 150°C.

Images