Modified vinyl aromatic copolymer, method for producing same, modified conjugated diene copolymer obtained from same, resin composition, crosslinked resin and structural member

Abstract

The present invention provides: a modified vinyl aromatic copolymer having reactivity and solubility which make the copolymer usable in the production of a copolymer rubber; and a copolymer rubber material which is obtained from the modified vinyl aromatic copolymer, and which exhibits processability, strength and homogeneity at the same time.　According to the present invention, structural units that are derived from a multifunctional vinyl aromatic compound (c) or an aromatic compound (d) that has 2 to 4 alkyl groups having 1 to 3 carbon atoms are contained in a polymer; and 50% by mole or more of the structural units derived from the component (c) or the component (d) are multifunctional structural units (e1) which are represented by formula (1) and have a group R1 that is derived from the aromatic structure of the component (c) or the component (d), and a group R2 or R3 that is derived from the component (c) or the component (d) excluding the aromatic structure. In the formula, R1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms; R2 represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R3 represents a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; and n represents an integer of 1 to 3. Meanwhile, "Polymer" in the formula represents a main polymer structural unit that is derived from the component (a) or the component (b).　The present invention provides a modified vinyl aromatic copolymer which is characterized in that: an end of the above-described polymer is modified with at least one functional group that is selected from the group consisting of an amino group, an alkoxysilyl group and a hydroxyl group; the average number of functional groups per one molecule is 2.0 or more; and the number-average molecular weight Mn is 500 to 30,000.　

Description

Modified vinyl aromatic copolymer and its method of production, modified conjugated diene copolymer obtained therefrom, resin composition, crosslinked resin product, and structural member

[0001] The present invention relates to a modified vinyl aromatic copolymer and a method for producing the same, a modified conjugated diene copolymer which is excellent in processability and which is excellent in tensile strength and abrasion resistance, a resin composition obtained from the copolymer, a cross-linked resin product obtained by cross-linking the copolymer, and a structural member.

[0002] Compounds containing multiple vinyl groups within the molecule are prone to intermolecular crosslinking reactions upon polymerization. Taking advantage of this property, such compounds can be added to a polymerization system and copolymerized to form crosslinked products, thereby insolubilizing the polymers or imparting functionality. For example, divinylbenzene is an example of a compound containing multiple vinyl groups within the molecule. Adding a small amount of this compound to a styrene polymerization system to copolymerize it and further introducing functional groups such as sulfonic acid groups can result in its use as an ion exchange resin. It is also used as a crosslinking agent for styrene-based resins such as synthetic rubber, ABS resin, MBS resin, and unsaturated polyester resin, and as a polyethylene modifier. Another example is the reaction of a branched polyfunctional vinyl aromatic copolymer with a thermoplastic resin, which is expected to impart functionality to the thermoplastic resin. For example, conjugated diene rubbers such as SBR (styrene-butadiene rubber), BR (butadiene rubber), IR (isoprene rubber), and styrene-isoprene rubber have excellent abrasion resistance, elasticity, and water resistance, and are used in a variety of applications, such as molding materials and resin modifiers.

[0003] One of the main applications of conjugated diene rubber is automobile tires. The properties required for tires include mechanical strength, abrasion resistance, wet grip performance, etc. (hereinafter, collectively referred to as "strength, etc."). Furthermore, in recent years, there has been active development of tires with excellent energy-saving performance, i.e., fuel-efficient performance (so-called "eco-tires"). These eco-tires are required to have low rolling resistance in addition to strength, etc.

[0004] It is known to add fillers (reinforcing fillers) such as carbon black and silica to conjugated diene rubber to ensure the strength and other properties of tires. However, terminal-modified solution-polymerized SBR (terminal-modified S-SBR) has attracted attention as a material that further improves the strength and other properties of tires and imparts excellent rolling resistance. Terminal-modified S-SBR has functional groups at the molecular terminals of the SBR, and these functional groups at the molecular terminals interact with the filler. This interaction improves the dispersibility of the filler in the SBR and also restricts the molecular terminals of the SBR, reducing mobility. As a result, tire hysteresis loss (internal friction) and rolling resistance are reduced. Taking advantage of these properties, eco-friendly tires that combine strength and low rolling resistance are being developed.

[0005] In such rubber compositions, various methods have been investigated for the purpose of improving the affinity between the polymer used as the raw rubber and the filler, for example, by introducing a specific functional group into the butadiene polymer, which is the raw rubber, to modify it. For example, Patent Document 1 discloses using an organolithium compound as an initiator in a non-polar solvent to synthesize a block copolymer consisting of an α-methylstyrene block and a butadiene block by living anionic polymerization, and then optionally reacting with a multifunctional coupling agent. Patent Document 2 discloses a star-shaped block interpolymer having a random copolymer block of a conjugated diene and a monovinyl aromatic monomer, a polyconjugated diene block, and a functional group derived from a multifunctional lithium-based initiator. The techniques of Patent Documents 1 and 2 are believed to be effective in ensuring the processability of the rubber by introducing a branched structure into the rubber component. However, no particular ingenuity has been put into the interaction with the filler to ensure strength, and the contribution to strength is insufficient. Patent Document 3 discloses a rubber composition comprising a rubber blend containing multiple diene rubbers and a predetermined amount of carbon black, and a low-molecular-weight functional group-containing polymer having a functional group at the molecular chain end that interacts with the carbon black and having a polymer structure similar to the rubber component of the diene rubber. However, this technology does not sufficiently contribute to strength because it involves compounding a low-molecular-weight compound with the rubber. Patent Document 4 discloses a rubber composition containing crosslinked rubber particles containing conjugated diene units, aromatic vinyl units, and units having at least two polymerizable unsaturated groups, and a conjugated diene / aromatic vinyl copolymer rubber containing conjugated diene units with a specific bonding structure. However, at least one of the functional groups selected from carboxylic acid groups, amino groups, hydroxyl groups, epoxy groups, and alkoxysilyl groups introduced into the three-dimensionally crosslinked crosslinked rubber particles penetrates into the insoluble network structure of the crosslinked rubber particles and is unable to contribute to the dispersibility of inorganic fillers outside the crosslinked rubber particles, resulting in an insufficient effect of introducing the functional groups.Patent Document 5 discloses a conjugated diene rubber comprising an interpenetrating network structure polymer composed of a crosslinked polymer having structural units derived from an ethylenically unsaturated compound and structural units derived from a crosslinking compound, the homopolymer of which has a glass transition temperature of 10°C or higher, and a non-crosslinked polymer having structural units derived from a conjugated diene compound. However, the crosslinked polymer is a three-dimensionally crosslinked, solvent-insoluble polymer, and even when the non-crosslinked polymer having structural units derived from a conjugated diene compound forms an interpenetrating network structure polymer, the polymer has a structurally brittle microgel, and therefore the effect of improving mechanical strength is insufficient. Patent Document 6 discloses crosslinked polymer particles having polysiloxane on the particle surface and an average particle size of 0.01 to 10 μm. However, because the polysiloxane-modified crosslinked polymer particles are solvent-insoluble crosslinked polymer particles and are hard and brittle, their use in modifying conjugated diene copolymers synthesized by anionic polymerization does not improve strength. Patent Document 7 discloses that modified polymer molecules can be obtained by reacting a divinylidene polymerization initiator with a monomer to form an "omega,omega'-carbanion" living polymer molecule, and then reacting at least one living polymer molecule with at least one equivalent of a chain end modifier. However, adding divinylbenzene as a coupling agent later results in the formation of a microgel, which is problematic in that it is insufficient in improving strength. Patent Document 8 discloses a crosslinked polymer containing a silylated ferrocenyl diphosphine ligand, which is prepared by swelling a polymer obtained by crosslinking aminomethylated polystyrene with 1% divinylbenzene in methylene chloride and then reacting it with tolylene 2,4-diisocyanate (TDI). However, it suggests that the crosslinked polymer is not solvent-soluble, and solvent-soluble branched polymers are not conceivable.Patent Document 9 discloses a modified resin composition obtained by blending an antioxidant, a silane coupling agent, and a radical initiator with a copolymer (cross-copolymer) having an ethylene-styrene-divinylbenzene copolymer chain and a polystyrene chain, the copolymer being obtained by anionic polymerization in the presence of an ethylene-styrene-divinylbenzene copolymer obtained by coordination polymerization and a styrene monomer, and kneading the resulting mixture. However, the cross-copolymer has a divinylbenzene content well below 0.5 mol %, and there is no indication as to whether a post-added silane coupling agent modifies the end of the cross-copolymer, nor is there any suggestion that coupling a living conjugated diene polymer could improve the properties of the conjugated diene polymer.

[0006] In view of the above problems, the present applicant has disclosed that a copolymer rubber having processability, strength, and homogeneity can be provided by using a specific polyfunctional vinyl aromatic copolymer having both a branched structure and the ability to interact with fillers as a constituent unit of a conjugated diene rubber (Patent Document 10). Furthermore, Patent Documents 11 to 14 propose polyfunctional vinyl aromatic copolymers essentially comprising an indane structural unit, a structural unit derived from a cycloolefin compound, or a structural unit derived from styrene. The present invention contributes to the modification of resins by a method different from the methods disclosed in Patent Documents 10 to 14, and proposes a material that is particularly useful for rubber compositions such as tires and can contribute to improving properties such as strength and abrasion resistance.

[0007] Japanese Patent Laid-Open No. 2003-73434 Japanese Patent Laid-Open No. 2004-517202 Japanese Patent Laid-Open No. 2005-213381 International Publication No. 2002 / 000779 Japanese Patent Laid-Open No. 2013-155268 Japanese Patent Laid-Open No. 7-207029 Japanese Patent Laid-Open No. 2016-530361 Japanese Patent Laid-Open No. 8-259584 Japanese Patent Laid-Open No. 2012-92197 International Publication No. 2018 / 084128 Japanese Patent Laid-Open No. 2004-123873 Japanese Patent Laid-Open No. 2018-39995 International Publication No. 2018 / 181842 International Publication No. 2020 / 67336

[0008] The present invention aims to solve these problems and to provide a modified vinyl aromatic copolymer that has reactivity and solubility and can be used to produce a modified conjugated diene copolymer having a highly branched structure without producing a small amount of by-production of microgel; a resin composition having a branched structure that combines processability, strength, and homogeneity; a cross-linked resin product obtained by cross-linking the same; and a structural member.

[0009] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a polymer containing structural units derived from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, in which 50 mol % or more of the structural units derived from component (c) or component (d) are polyfunctional structural units (e1) represented by the following formula (1):

[0010] The present invention provides a polymer comprising structural units derived from one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b), the polymer containing structural units derived from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, wherein 50 mol % or more of the structural units derived from component (c) or component (d) are polyfunctional structural units (e1) represented by the following formula (1) having a group R1 derived from the aromatic structure of component (c) or component (d) and a group R2 or R3 derived from a structure other than the aromatic structure of component (c) or component (d): Here, R1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R2 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer from 1 to 3. Polymer represents a main polymer structural unit derived from component (a) or component (b). The modified vinyl aromatic copolymer is further characterized in that the terminals of the polymer are modified with at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, the average number of functional groups per molecule is 2.0 or more, and the number average molecular weight Mn is 500 to 30,000.

[0011] The modified vinyl aromatic copolymer preferably comprises a polyfunctional structural unit (e1) represented by formula (1) produced by reacting component (c) or (d) with an organic alkali metal compound, where R3 is a group partially containing a structure derived from the organic alkali metal compound or a hydrogen atom that does not contain the structure. The modified vinyl aromatic copolymer preferably contains 0.5 mol% to 35.0 mol% of structural units derived from the polyfunctional vinyl aromatic compound (c) or the aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, and 65.0 mol% to 99.5 mol% of structural units derived from one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b). The molecular weight distribution (Mw / Mn), expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is preferably 10.0 or less. The average number of functional groups per molecule may be in the range of 2 to 20. Examples of the monovinyl aromatic compound include styrene, vinylnaphthalene, vinylbiphenyl, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, m-ethylvinylbenzene, indene, and p-ethylvinylbenzene.

[0012] The present invention also provides a method for producing a modified vinyl aromatic copolymer according to any one of claims 1 to 5, comprising: an initiation reaction step of reacting an alkali metal compound with one or more compounds selected from the group consisting of a polyfunctional vinyl aromatic compound (c) and an aromatic compound (d) having 2 to 4 alkyl groups of 1 to 3 carbon atoms to produce a polyfunctional anionic polymerization initiator; a polymerization step of polymerizing one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b) to obtain a vinyl aromatic copolymer having a polyfunctional structural unit (e1) represented by formula (1) and an active terminal; and a terminal modification step of reacting the active terminal of the vinyl aromatic copolymer with a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, or a precursor compound thereof, to form a functional group.

[0013] Furthermore, the present invention relates to a modified conjugated diene copolymer obtained by reacting a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound with the above-mentioned modified vinyl aromatic copolymer.

[0014] The modified conjugated diene copolymer may contain 0.001 to 6 wt% of structural units (A1) derived from a modified vinyl aromatic copolymer, 29 to 99.999 wt% of structural units (B1) derived from a conjugated diene compound, and 0 to 70 wt% of structural units (C1) derived from an aromatic vinyl compound. In a differential molecular weight distribution curve obtained by gel permeation chromatography (GPC), the area of ​​a region having a number average molecular weight (Mn) three times or more (3 Mp or more) the lowest molecular weight peak should preferably account for 20% or more of the total area taken as 100%.

[0015] The present invention also provides a resin composition comprising 0.5 to 200 parts by weight of at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, per 100 parts by weight of the modified conjugated diene copolymer.

[0016] The resin composition may further contain a crosslinking agent. The present invention also relates to a crosslinked resin product obtained by crosslinking a resin composition further containing a crosslinking agent. The present invention also relates to a structural member comprising this crosslinked resin product.

[0017] The modified vinyl aromatic copolymer of the present invention can be used as a raw material for modified conjugated diene copolymers. Furthermore, a crosslinked resin composition obtained by crosslinking this modified conjugated diene copolymer with a filler exhibits excellent filler dispersibility, mechanical strength, and abrasion resistance, making it useful as an elastomer material for tires (especially tire treads), seismic isolation rubber, rubber hoses, rubber rollers, footwear materials, and the like. It can also be used as a molding material, a resin modifier, and the like. It can be used in fields such as the electrical and electronics industries, the aerospace and aircraft industries, and the building and construction industries, as a dielectric material, an insulating material, a heat-resistant material, a structural material, an adhesive, a sealant, a paint, a coating agent, a sealant, a printing ink, a dispersant, and the like. Furthermore, films and sheets coated with a curable resin composition containing the modified vinyl aromatic copolymer of the present invention are suitable for use in plastic optical components, touch panels, flat displays, film liquid crystal elements, and the like. The modified vinyl aromatic copolymer of the present invention can also be used as a modifier to modify the properties such as heat resistance, dielectric properties, adhesiveness / adhesion, and optical properties of thermoplastic resins or curable resin compositions used as the main material for films, sheets, and prepregs. Furthermore, curable resin compositions containing the polyfunctional vinyl aromatic copolymer of the present invention as the main material can also be processed into films, sheets, and prepregs for use. Furthermore, curable resin compositions containing the modified vinyl aromatic copolymer of the present invention can also be used as various optical elements such as optical waveguides and optical lenses.

[0018] 1 shows a GPC chart showing the peak top molecular weight (Mp), a molecular weight twice the Mp (2 Mp), and a molecular weight three times the Mp (3 Mp).

[0019] The modified vinyl aromatic copolymer of the present invention (hereinafter also referred to as modified copolymer or copolymer) is a polymer comprising structural units derived from one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b), and the polymer contains structural units derived from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, and 50 mol % or more of the structural units derived from compound (c) or compound (d) are polyfunctional structural units (e1) represented by the following formula (1) having a group R1 derived from the aromatic structure of component (c) or component (d) and a group R2 or R3 derived from a structure other than the aromatic structure of component (c) or component (d): Here, R1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R2 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer from 1 to 3. Polymer represents the main polymer structural unit derived from component (a) or component (b). Furthermore, the terminals of the polymer are modified with at least one functional group selected from the group consisting of amino groups, alkoxysilyl groups, and hydroxyl groups, and the average number of functional groups per molecule is 2.0 or more, and the number average molecular weight Mn is 500 to 30,000.

[0020] The modified vinyl aromatic copolymer of the present invention contains structural units derived from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups each having 1 to 3 carbon atoms, and at least 50 mol% of the structural units derived from component (c) or component (d) are polyfunctional structural units (e1) represented by the above formula (1) formed by the reaction of component (c) or component (d) with an organic alkali metal compound, and these polyfunctional structural units (e1) or (e2) play an important role as crosslinking components that branch the copolymer and make it multifunctional. When a polyfunctional modified vinyl aromatic copolymer is used to modify polymers of a conjugated diene compound, high molecular weight multi-branched components are formed, enabling improved abrasion resistance.

[0021] Preferred examples of the polyfunctional vinyl aromatic compound (c) include, but are not limited to, diisopropenylbenzene, divinylbenzene, diisopropenylnaphthalene, divinylnaphthalene, diisopropenylbiphenyl, and divinylbiphenyl. Each of the exemplified compounds may be an isomer such as the m-isomer or the p-isomer, or a mixture of these isomers. Preferred examples of the aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms include, but are not limited to, xylene, trimethylbenzene, diethylbenzene, triethylbenzene, dipropylbenzene, tripropylbenzene, dimethylnaphthalene, trimethylnaphthalene, diethylnaphthalene, triethylnaphthalene, dipropylnaphthalene, tripropylnaphthalene, dimethylbiphenyl, trimethylbiphenyl, diethylbiphenyl, triethylbiphenyl, dipropylbiphenyl, and tripropylbiphenyl. In each of the exemplified compounds, the di-substitution may be an isomer such as the m-form or p-form, or a mixture of these isomers, and the tri-substitution may be an isomer such as a 1,2,4-tri-substituted or a 1,3,5-tri-substituted isomer, or a mixture of these isomers. (c) and (d) may be used alone or in combination of two or more. That is, (c) and (d) may be combined. From the viewpoint of moldability, more preferred are diisopropenylbenzene (m-form, p-form, or a mixture of these isomers), divinylbenzene (m-form, p-form, or a mixture of these isomers), xylene (m-form, p-form, or a mixture of these isomers), and diethylbenzene (m-form, p-form, or a mixture of these isomers).

[0022] On the other hand, the monovinyl aromatic compound (a), which is a structural unit contained in the modified vinyl aromatic copolymer of the present invention, improves the solvent solubility, compatibility, and processability of the copolymer. Examples of monovinyl aromatic compounds include, but are not limited to, vinyl aromatic compounds such as styrene, vinylnaphthalene, vinylbiphenyl, and α-methylstyrene; nuclear alkyl-substituted vinyl aromatic compounds such as o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylvinylbenzene, m-ethylvinylbenzene, and p-ethylvinylbenzene; and cyclic vinyl aromatic compounds such as indene, acenaphthylene, benzothiophene, and coumarone. In order to prevent gelation of the copolymer and improve its solubility in solvents, compatibility, and processability, styrene, ethylvinylbenzene, ethylvinylbiphenyl, ethylvinylnaphthalene, and indene are particularly preferred from the standpoints of cost and availability. Each of the exemplified compounds may be an isomer such as the m-isomer or p-isomer, or a mixture of these isomers. From the viewpoint of compatibility and cost, styrene, ethylvinylbenzene (m-isomer, p-isomer or a mixture of these isomers), and p-methylstyrene are more preferred.

[0023] The conjugated diene compound (b), which is a structural unit contained in the modified vinyl aromatic copolymer of the present invention, 1) enhances the introduction efficiency of the modifying group introduced into the modified vinyl aromatic copolymer, and 2) has the function of enhancing the reactivity of the terminal modifying group of the modified vinyl aromatic copolymer when the modified vinyl aromatic copolymer is reacted with a polymer of a conjugated diene compound having an active end or a copolymer of a conjugated diene compound having an active end and an aromatic vinyl compound.

[0024] The conjugated diene compound is preferably a conjugated diene compound containing 4 to 12 carbon atoms per molecule, more preferably a conjugated diene compound containing 4 to 8 carbon atoms. Examples of such conjugated diene compounds include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoints of ease of copolymerization with aromatic vinyl compounds and ease of industrial availability. These compounds may be used alone or in combination of two or more.

[0025] The modified vinyl aromatic copolymer of the present invention is modified with a polymerization initiator or modifier having at least one functional group selected from the group consisting of an amino group (-NR), an alkoxysilyl group (Si-OR), and a hydroxyl group (-OH). The amount of modifier introduced per molecule corresponds to the "average number of functional groups per molecule." The modified vinyl aromatic copolymer of the present invention has an average number of functional groups per molecule of 2.0 or more. If the value obtained by dividing the number average molecular weight of the copolymer by the functional group equivalent is 2.0 or more, it can be determined that two or more groups are functionalized. The amount of functional group-containing polymerization initiator or modifier introduced per molecule is preferably 2.0 to 20, more preferably 2.0 to 10.0, and even more preferably 2.0 to 6.0 terminal functional groups. 2.0 to 4.0 terminal functional groups are particularly preferred.

[0026] The modified vinyl aromatic copolymer of the present invention can be produced, for example, by the following method: that is, the method includes an initiation reaction step of reacting an organic alkali metal compound with one or more compounds selected from polyfunctional vinyl aromatic compounds (c) and aromatic compounds (d) having 2 to 4 alkyl groups of 1 to 3 carbon atoms to produce a polyfunctional anionic polymerization initiator, a polymerization step of polymerizing one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b) to obtain a vinyl aromatic copolymer having a polyfunctional structural unit (e1) represented by formula (1) and an active terminal, and a terminal modification step of reacting the active terminal of the vinyl aromatic copolymer with a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, or a precursor compound thereof, to form a functional group.

[0027] The modified vinyl aromatic copolymer of the present invention is a copolymer containing a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, a structural unit (a) derived from a monovinyl aromatic compound, and a structural unit (b) derived from a conjugated diene compound. However, within the scope that does not impair the effects of the structural units derived from components (a) to (d), compounds other than the conjugated diene compound and the aromatic vinyl compound (hereinafter also referred to as "other monomers") can be used to introduce structural units derived from these other monomers (f) into the copolymer.

[0028] Specific examples of the other monomer (f) include, but are not limited to, acrylonitrile, methyl (meth)acrylate, and ethyl (meth)acrylate. These can be used alone or in combination of two or more. The other monomer (f) is preferably used in an amount of less than 30 mol% of the total monomers. As a result, the structural units derived from the other monomer (f) are introduced in an amount of less than 30 mol% of the total amount of structural units in the copolymer. The amount is preferably 10 mol% or less, and more preferably 5 mol% or less.

[0029] In the method for producing a modified vinyl aromatic copolymer of the present invention, in the initiation reaction step, an alkali metal compound is reacted with one or more compounds selected from the group consisting of a polyfunctional vinyl aromatic compound (c) and an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms to produce a polyfunctional anionic polymerization initiator.

[0030] The structural unit of the polyfunctional anionic polymerization initiator produced in the initiation reaction step undergoes a polymerization step to become a polyfunctional structural unit (e1) represented by the following formula (1). In formula (1), R1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R2 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer from 1 to 3. Polymer represents the main polymer structural unit derived from component (a) or (b). It is necessary that 50 mol % or more of the structural units derived from component (c) or (d) are polyfunctional structural units (e1) represented by formula (1) having a group R1 derived from the aromatic structure of component (c) or (d) and a group R2 or R3 derived from a structure other than the aromatic structure of component (c) or (d). This proportion is preferably 70 mol % or more, more preferably 80 mol % or more, and particularly preferably 90 mol % or more. The proportion of polyfunctional structural units (e1) among the structural units derived from component (c) or (d) is also referred to as the degree of polyfunctional structure. In the modified vinyl aromatic copolymer of the present invention, either or both of the following are used as raw materials: (c) component: a polyfunctional vinyl aromatic compound (c); (d) component: an aromatic compound (d) having 2 to 4 alkyl groups each having 1 to 3 carbon atoms. When the (c) component is used as the raw material, R2 is a hydrogen atom at the α-position of the vinyl group or a hydrocarbon group having 1 to 6 carbon atoms. For example, butyl Li(C ４ H ９ When butyl Li is used, an active species is generated by the reaction between butyl Li and component (c), as shown in the following reaction formula: Therefore, the pentyl group formed by adding the carbon at the β-position of the vinyl group and the butyl group derived from butyl Li represents R3. On the other hand, when component (d) is used, the reaction between component (d) and the organic alkali metal compound initiator, for example, butyl Li, is a chain transfer reaction as shown in the following reaction formula: In this case, the hydrogen atom remaining after one hydrogen atom is abstracted from the carbon atom becomes R3.

[0031] The proportion of the polyfunctional structural unit (e1) represented by formula (1) among the structural units derived from component (c) or component (d) (polyfunctionality) is a parameter that can be arbitrarily controlled and varied, but if this ratio is less than 50 mol%, a large amount of modified vinyl aromatic copolymer with an average functional group number of 1.0 per molecule will be contained, and when this polymer is used to modify a conjugated diene (co)polymer, the branching reaction will not proceed sufficiently, so the molecular weight will not increase sufficiently, and the improvement effect on strength and abrasion resistance will tend to be small. The residual vinyl content (mol%) derived from component (c) in the modified vinyl aromatic copolymer indicates the content of component (c) containing residual vinyl groups derived from component (c) relative to the total content of component (c), and is preferably 30 mol% or less, more preferably 20 mol% or less. Particularly preferably 10 mol% or less, most preferably 5 mol% or less. Here, by limiting the residual vinyl content to a range of 30 mol% or less, the amount of modifier introduced is increased. Therefore, when this polymer is used to modify a conjugated diene (co)polymer, the molecular weight increases and the number of functional groups increases, which is preferable because it achieves both good dispersibility of the filler and good abrasion resistance.

[0032] The organic alkali metal compound used in the initiation reaction step in the method for producing a modified vinyl aromatic copolymer of the present invention is not particularly limited, but is preferably an organic lithium compound. Specific examples include alkyl lithiums such as methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, and t-butyl lithium, as well as phenyl lithium, stilbene lithium, and naphthyl lithium. The amount of the organic alkali metal compound used is preferably 0.5 to 1.0 times the molar amount of the total vinyl groups and alkyl groups in one or more compounds selected from the polyfunctional vinyl aromatic compound (c) or the aromatic compound (d) having 2 to 4 alkyl groups containing 1 to 3 carbon atoms. More preferably, it is 0.7 to 1.0 times the molar amount. If the amount of alkali metal compound used is less than 0.5 times the molar amount, when this polymer is used to modify a conjugated diene (co)polymer, the branching reaction does not proceed sufficiently, resulting in an insufficient increase in molecular weight and a tendency for the improvement in strength and abrasion resistance to be reduced. On the other hand, if the alkali metal compound is used in an amount exceeding 1.0 times by mole, gel tends to form when this polymer is used to modify a conjugated diene (co)polymer. The amount of polyfunctional anionic polymerization initiator obtained by reacting an alkali metal compound with one or more compounds selected from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms is preferably 5.0 to 100 mmol per 100 g of monomer used in polymerization. The initiation reaction step may be carried out using a mixture of an alkali metal compound and a compound having a functional group that interacts with silica. By carrying out the initiation reaction in the presence of this mixture, the polymerization initiation terminal of the modified vinyl aromatic copolymer of the present invention can be modified with a functional group that interacts with silica. In this specification, the term "functional group that interacts with silica" refers to a group having an element that interacts with silica, such as nitrogen, sulfur, phosphorus, or oxygen.The term "interaction" means the formation of a covalent bond between molecules or the formation of an intermolecular force weaker than a covalent bond (for example, an electromagnetic force acting between molecules such as an ion-dipole interaction, a dipole-dipole interaction, a hydrogen bond, or a van der Waals force). As the compound having a functional group that interacts with silica, which is used to modify the polymerization initiation terminal, nitrogen-containing compounds such as secondary amine compounds are particularly preferred. Specific examples of the nitrogen-containing compound include dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, di-(2-ethylhexyl)amine, diallylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine, and 1,3-ditrimethylsilyl-1,3,5-triazinane.

[0033] A polar compound may be added in the initiation reaction step. The addition of a polar compound contributes to the initiation reaction and propagation reaction, and is effective in controlling the molecular weight and molecular weight distribution, accelerating the polymerization reaction, and the like. Examples of polar compounds include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium tert-amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more. The amount of polar compound used is not particularly limited and can be selected depending on the purpose, etc. Usually, it is preferably 0.01 to 100 moles per mole of the alkali metal compound.

[0034] The copolymerization of a divinyl aromatic compound and a monomer containing a monovinyl aromatic compound is preferably carried out by solution polymerization in an inert solvent. The polymerization solvent is not particularly limited, and hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons can be used. Specific examples include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, and decalin; and aromatic hydrocarbons such as benzene, toluene, and xylene, as well as hydrocarbon solvents consisting of mixtures thereof. The above-mentioned monomers and polymerization solvents are preferably treated, either individually or in mixtures, with an organometallic compound. This allows the treatment of monomers such as the divinyl aromatic compound and the monovinyl aromatic compound, as well as allenes and acetylenes contained in the polymerization solvent. As a result, a polymer with a high concentration of active terminals can be obtained, achieving a high modification rate.

[0035] The polymerization temperature during copolymerization is not particularly limited as long as it is a temperature at which living anionic polymerization proceeds, but from the viewpoint of productivity, it is preferably −20° C. to 150° C., and from the viewpoint of ensuring a sufficient amount of reaction with active terminals in the terminal modification step after completion of polymerization, it is preferably −20° C. to 120° C., and more preferably 0° C. to 100° C.

[0036] The polymerization reaction may be carried out in any manner, including but not limited to, a batchwise manner (also called a "batchwise manner"), a continuous manner, or the like. In a continuous manner, one or more connected reactors may be used. The reactor may be a tank type or a tubular type equipped with an agitator. In a batchwise manner, the molecular weight distribution of the resulting polymer is generally narrow, with Mw / Mn tending to be 1.0 or more and less than 3.0. In a continuous manner, the molecular weight distribution is generally broad, with Mw / Mn tending to be 1.5 or more and less than 10.

[0037] In the production method of the present invention, a vinyl aromatic copolymer having a polyfunctional structural unit (e1) represented by formula (1) and an active terminal is obtained by reacting component (c) or component (d) with an organic alkali metal compound in the polymerization step. Then, a compound (including a precursor, also referred to as a modifier) ​​having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group is reacted with the active terminal to introduce a functional group into the terminal of the modified vinyl aromatic copolymer of the present invention. The modifier reacts with the active terminal of the copolymer and, in the present invention, bonds to the active terminal derived from the conjugated diene compound (b). It is preferable that the modifier bond to the active terminal derived from the conjugated diene compound (b) is 50 mol% or more in order to increase the molecular weight of the modified conjugated diene copolymer and improve wear resistance when used as an automobile tire. The proportion of the modifier bonded to the active terminal derived from the conjugated diene compound (b) is 70 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and particularly preferably 90 mol% or more.

[0038] When reacting a compound (including a precursor) having a functional group at an active terminal, the reaction temperature, reaction time, etc. are not particularly limited, but it is preferable to react at -20°C to 120°C for 30 seconds or more. The amount of functional group-containing modifier added is not particularly limited, but it is preferable that the total number of moles of functional group-containing modifier is in the range of 0.3 to 6 times the number of equivalents of the active species derived from the polyfunctional anionic polymerization initiator obtained by reacting an alkali metal compound with one or more compounds selected from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms in the initiation reaction step. A more preferred lower limit is 0.5, even more preferably 0.7, and particularly preferably 0.9. On the other hand, a more preferred upper limit is 3 times, even more preferably 2 times, and particularly preferably 1.5 times. An amount of 0.3 times or more is preferable from the viewpoint of obtaining a sufficient modification rate in the target modified vinyl aromatic copolymer.

[0039] In the terminal modification step, if the polymerization step is a batch process, the modification reaction may be carried out in the reactor used in the polymerization step, or the reaction mixture may be transferred to a subsequent reactor. In the case of a continuous polymerization step, the reaction mixture is transferred to a subsequent reactor. The terminal modification step is preferably carried out immediately following the polymerization step, and the modifier is mixed and the reaction is carried out preferably within 5 minutes. The reactor for the modification reaction is preferably one that provides sufficient stirring. Specific examples include a static mixer reactor, a tank-type reactor equipped with an agitator, and the like.

[0040] The terminal modification step is a step of modifying the active terminal of the vinyl aromatic copolymer by reacting it with a modifying agent having at least one functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group. The modifying agent must have an amino group, an alkoxysilyl group, or a hydroxyl group as the functional group, and may have other functional groups, such as a halogen group, a ketone group, an ester group, an amide group, or an epoxy group, as long as the object of the present invention is not impaired.

[0041] The modifying agent having an amino group is not particularly limited, but specifically includes a compound having an amino group and a functional group that bonds with the active terminal of a polymer in the molecule, preferably a compound that does not have active hydrogen.The amino group is not particularly limited, but specifically, a functional group that is inert to alkali metals is preferred, and a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, or an amino group with two hydrogens protected is preferred.In addition, examples of the protected monosubstituted amino group or the amino group with two hydrogens protected include those in which one hydrogen of the monosubstituted amino group or two hydrogens of the amino group are respectively substituted with a trialkylsilyl group.

[0042] The modifier having an alkoxysilyl group is not particularly limited, but specific examples include compounds having multiple alkoxysilyl groups in the molecule (including compounds having a silyl group to which multiple alkoxy groups are bonded), and compounds having an alkoxysilyl group and a functional group bonded to the active terminal of a polymer in the molecule. Note that these are preferably compounds that do not have active hydrogen.

[0043] The modifier that forms a hydroxyl group is not particularly limited, but specifically includes a compound having a functional group that bonds with the active terminal of the polymer and generates a hydroxyl group after the bonding reaction, and a compound having a functional group that does not bond with the active terminal of the polymer and generates a hydroxyl group by a subsequent reaction such as hydrolysis, and is preferably a compound that does not have active hydrogen. Examples of the compound having a functional group that generates a hydroxyl group after the bonding reaction include compounds having a ketone group, an ester group, an amide group, an epoxy group, etc. Furthermore, examples of the compound having a functional group that generates a hydroxyl group by a reaction such as hydrolysis after the bonding reaction include compounds having an alkoxysilyl group, an aminosilyl group, etc.

[0044] Specific examples of modifying agents are shown below. Examples of compounds that bond with active polymer terminals to form amino groups at the terminals of the polymer include, but are not limited to, C═N double bond compounds such as N,N'-dicyclohexylcarbodiimide. Examples of compounds that bond with active polymer terminals to form amino and hydroxyl groups at the terminals of the polymer include, but are not limited to, ketone compounds having an amino group such as N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone (Michler's ketone) and N,N,N',N'-tetraethyl-4,4'-diaminobenzophenone; cyclic urea compounds such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; cyclic amides, i.e., lactam compounds; amino-containing epoxy compounds such as N,N,N',N'-tetraglycidyl-1,3-bisaminomethylcyclohexane; and epoxy compounds having a nitrogen-containing heterocyclic group as described in JP 2001-131227 A. Examples of compounds that bond with active polymer terminals to form alkoxysilyl groups at the terminals of the polymer include, but are not limited to, halogenated alkoxysilane compounds such as trimethoxychlorosilane, triethoxychlorosilane, and diphenoxydicylic acid silane; and polyfunctional alkoxysilane compounds such as bis(trimethoxysilyl)ethane and bis(3-triethoxysilylpropyl)ethane. Examples of compounds that bond with active polymer terminals to form alkoxysilyl groups and hydroxyl groups at the terminals of the polymer include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and polysiloxane compounds having an epoxy group and an alkoxysilyl group in the molecule.

[0045] The compound that bonds with the active terminal of a polymer to form an amino group and an alkoxysilyl group at the terminal of the polymer is not particularly limited, but may be an alkoxysilane compound to which an alkyl group having an amino substituent is bonded, such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminopropyltriethoxysilane, bis(3-trimethoxysilylpropyl)methylamine, or bis(3-triethoxysilylpropyl)methylamine; alkoxysilane compounds having a protected mono-substituted amino group bonded thereto, such as N-[2-(trimethoxysilanyl)-ethyl]-N,N',N'-trimethylethane-1,2-diamine, 1-[3-(triethoxysilyl)-propyl]-N,N'-diethyl-N'-trimethylsilyl-ethane-1,2-diamine, and 3-(4-trimethylsilyl-1-piperazinyl)propyltriethoxysilane; Alkoxysilane compounds having a plurality of substituted amino groups bonded thereto, as described in WO 2008 / 013090, such as 1,4-tylpiperazine, 2-(trimethoxysilanyl)-1,3-dimethylimidazolidine, and bis-(3-dimethylaminopropyl)-dimethoxysilane; alkoxysilane compounds having a nitrogen-containing heterocycle bonded thereto, as described in WO 2011 / 040312, such as 1,4-bis[3-(trimethoxysilyl)propyl]piperazine and 1,4-bis[3-(triethoxysilyl)propyl]piperazine; Examples of the compound include alkoxysilane compounds having an azasilane group bonded thereto, such as those described in WO 2011 / 129425, such as [N,N-bis(trimethylsilyl)amino]propyltrimethoxysilane, 3-[N,N-bis(trimethylsilyl)amino]propylmethyldiethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, and 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane. Examples of the compound that bonds with the active terminal of a polymer to form a hydroxyl group at the terminal of the polymer include, but are not limited to, epoxy compounds such as ethylene oxide and propylene oxide; and ketone compounds such as benzophenone.

[0046] The modified vinyl aromatic copolymer of the present invention obtained by the above-described production method is modified with at least one reactive functional group selected from the group consisting of amino, alkoxysilyl, and hydroxyl groups. Therefore, although it may be molded and cured alone, it is preferable to use other polymerizable resins for functional group modification and synthesis of high-molecular-weight multi-branched components. In particular, the modified vinyl aromatic copolymer of the present invention is used for functional group modification and synthesis of high-molecular-weight multi-branched components when preparing a conjugated diene compound alone and / or a conjugated diene copolymer (rubber) obtained by copolymerizing a conjugated diene compound with other monomers. When the modified vinyl aromatic copolymer of the present invention is reacted with an organic alkali metal compound to initiate the reaction, multi-branched components that serve as the starting point for multiple branched chains are produced by reacting the component (c) or (d) with multiple organic alkali metal compounds. The proportion of multi-branched components derived from the component (c) or (d) is defined as the initiator-derived multifunctional structure degree, expressed as a molar fraction relative to the total amount of the raw material component (c) or (d). The initiator-derived polyfunctional structure degree is preferably 0.50 or more, more preferably 0.70 or more, even more preferably 0.80 or more, and particularly preferably 0.90 or more. By making the initiator-derived polyfunctional structure degree 0.50 or more, the amount of modifier introduced can be increased, and therefore, when this polymer is used to modify a conjugated diene-based (co)polymer, both filler dispersibility and abrasion resistance are achieved, which is preferable.

[0047] The modified copolymer of the present invention is an excellent modifier for conjugated diene (co)polymers (rubbers). While the detailed mechanism is unclear, it is presumed that the introduction of an appropriate amount of functional groups into the modified copolymer of the present invention modifies the rubber to form a modified conjugated diene copolymer (modified rubber), which tends to concentrate near the reinforcing filler, enhancing the reinforcing effect of the reinforcing filler and leading to improved abrasion resistance of the resulting crosslinked product. Furthermore, the use of modified rubber improves the affinity between the modified conjugated diene copolymer of the present invention and the reinforcing filler, resulting in an ideal dispersion state of each component, such as the reinforcing filler, in the resin composition for improving the physical properties of the resulting crosslinked product (e.g., improved abrasion resistance, improved handling stability, dry grip performance, wet grip performance). On the other hand, if the number of functional groups in the modified conjugated diene copolymer is too large, interactions between the copolymers adsorbed on the reinforcing filler will cause the reinforcing filler to aggregate, and this copolymer will not contribute to improving the affinity between the modified conjugated diene copolymer and the reinforcing filler.

[0048] The average number of functional groups per molecule of the modified vinyl aromatic copolymer can be calculated from the equivalent weight (g / eq) of the functional groups of the modified vinyl aromatic copolymer (A) and the number average molecular weight Mn in terms of styrene by the following formula (1): Average number of functional groups per molecule = [(number average molecular weight Mn) / (average molecular weight of divinyl aromatic compound unit and monovinyl aromatic compound)] / (equivalent weight of functional group) (1) The equivalent weight of the functional groups of the modified vinyl aromatic copolymer (A) means the mass of the divinyl aromatic compound unit and monovinyl aromatic compound bonded to each functional group. The equivalent weight of the functional group is １ H-NMR or １３ It can be calculated from the area ratio of the peak derived from the functional group to the peak derived from the polymer main chain using C-NMR.

[0049] The average number of functional groups per molecule in the modified vinyl aromatic copolymer (A) is preferably 2 to 20. More preferably, it is 2 to 10. Particularly preferably, it is 2 to 5. If the average number of functional groups per molecule exceeds 20, the viscosity increases when the reinforcing filler (D) is dispersed, processability deteriorates, and the abrasion resistance of the resulting crosslinked product tends to decrease. If the average number of functional groups per molecule is less than 2, the dispersibility of the reinforcing filler (D) is poor, which tends to be less than ideal for improving the physical properties of the crosslinked product in which the reinforcing filler (D) and other components are dispersed. The amount of modifier having at least one functional group selected from amino groups, alkoxysilyl groups, and hydroxyl groups added to the modified vinyl aromatic copolymer (A) can be determined using various analytical instruments, such as nuclear magnetic resonance spectroscopy.

[0050] The modified vinyl aromatic copolymer of the present invention contains 0.5 to 35.0 mol % of structural units derived from a polyfunctional vinyl aromatic compound (c) and an aromatic compound (d) having 2 to 4 alkyl groups each having 1 to 3 carbon atoms. When the structural units consist solely of structural units derived from (a), (b), (c), and (d), the proportion of structural units derived from the polyfunctional vinyl aromatic compound (c) and the aromatic compound (d) having 2 to 4 alkyl groups each having 1 to 3 carbon atoms is 0.005 to 0.35 relative to the total of the structural units derived from (a), (b), (c), and (d). This molar fraction is calculated using the following formula (2): [(c)+(d)] / [(a)+(b)+(c)+(d)] (2) (where (a): the molar fraction of structural units derived from the monovinyl aromatic compound (a), (b): the structural units derived from the conjugated diene compound (b), (c): the molar fraction of structural units derived from the divinylar aromatic compound (c), and the molar fraction of structural units derived from the aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms.) The lower limit of the molar fraction is preferably 0.006, more preferably 0.007. The upper limit is preferably 0.35, more preferably 0.30. Optimally, it is 0.01 to 0.25. Note that, when structural units other than those derived from (a), (b), (c), and (d) are contained, the lower limit of the content is preferably 0.2 mol%, more preferably 0.4 mol%, and even more preferably 0.6 mol%. The upper limit is preferably 35 mol %, more preferably 30 mol %, and even more preferably 25 mol %.

[0051] The modified vinyl aromatic copolymer of the present invention contains 65.0 to 99.5 mol % of structural units derived from one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b). In terms of mole fraction, it is 0.65 to 0.995. A preferred lower limit is 0.70. A more preferred lower limit is 0.75. A preferred upper limit is 0.994, more preferably 0.993. Optimally, it is 0.75 to 0.99.

[0052] The mole fraction of structural units derived from one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b) is calculated by the following mathematical formula (3) when the composition consists only of structural units (a), (b), (c), and (d): [(a) + (b)] / [(a) + (b) + (c) + (d)] (3) (wherein (a), (b), (c), and (d) have the same meanings as in mathematical formula (3).) Even when the composition contains structural units other than those derived from (a), (b), (c), and (d), the preferred mole fractions of structural units derived from (a) and (b) are within the above range.

[0053] The modified vinyl aromatic copolymer of the present invention may contain other structural units in addition to the above structural units, the details of which will be understood from the description of the production method.

[0054] The Mn (number average molecular weight in terms of standard polystyrene as measured by gel permeation chromatography) of the modified vinyl aromatic copolymer of the present invention is 500 to 30,000. A preferred lower limit is 600, more preferably 700, even more preferably 800, and particularly preferably 900. On the other hand, a preferred upper limit is 25,000, more preferably 20,000, even more preferably 15,000, and particularly preferably 10,000. If Mn is less than 500, the amount of functional groups contained in the copolymer will decrease, tending to reduce reactivity with the active terminals of the conjugated diene copolymer. If Mn exceeds 30,000, gel will be more likely to form and moldability and tensile elongation at break will tend to decrease. The preferred upper limit of the molecular weight distribution (Mw / Mn) is 10.0 or less, more preferably 5.0 or less, and particularly preferably 3.0. If Mw / Mn exceeds 10.0, the processability of the copolymer rubber will tend to deteriorate and gel will tend to form.

[0055] The modified vinyl aromatic copolymer of the present invention is soluble in a solvent selected from toluene, xylene, tetrahydrofuran, dichloroethane, and chloroform, and is preferably soluble in any of the above solvents. It is preferable that the copolymer dissolves in an amount of 50 g or more, and more preferably 80 g or more, in 100 g of the solvent.

[0056] The modified vinyl aromatic copolymer of the present invention thus obtained has at least one reactive functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, and therefore may be molded and cured alone, but it is preferable to use other polymerizable resins for functional group modification and synthesis of high molecular weight multi-branched components. In particular, the modified vinyl aromatic copolymer of the present invention is used for functional group modification and synthesis of high molecular weight multi-branched components when obtaining a conjugated diene copolymer (rubber) obtained by copolymerizing a conjugated diene compound alone and / or a conjugated diene compound with other monomers.

[0057] By copolymerizing the polyfunctional vinyl aromatic copolymer (A) of the present invention with 1) a conjugated diene compound (B), or 2) a conjugated diene compound (B) and an aromatic vinyl compound (C) as raw materials, a modified conjugated diene copolymer having a branched polymer-type modifying group (A) based on the modified vinyl aromatic copolymer of the present invention can be obtained. When the aromatic vinyl compound (C) is not used, modified diene rubbers such as butadiene rubber and isoprene rubber can be obtained, and when the aromatic vinyl compound (C) is used, modified conjugated diene copolymers such as modified SBR can be obtained. These modified conjugated diene copolymers exhibit rubber properties and are therefore also called modified copolymer rubbers.

[0058] The polymerization step for obtaining the modified conjugated diene copolymer of the present invention comprises a polymerization step of polymerizing a conjugated diene compound (B) or copolymerizing a conjugated diene compound (B) and an aromatic vinyl compound (C) using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator to obtain a conjugated diene copolymer having an active terminal, and a terminal modification step of introducing a branched polymer-type modifying group (A) based on the modified vinyl aromatic copolymer.

[0059] Examples of the conjugated diene compound (B) include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferred. These may be used alone or in combination of two or more.

[0060] As the aromatic vinyl compound (C), styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, vinylxylene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, tert-butoxydimethylsilylstyrene, isopropoxydimethylsilylstyrene, and the like can be used alone or in combination of two or more kinds, with styrene being particularly preferred among these.

[0061] When 1,3-butadiene is used as the conjugated diene compound (B) and styrene is used as the aromatic vinyl compound, so-called styrene-butadiene rubber (SBR) is obtained. Furthermore, when styrene is not used as the aromatic vinyl compound and 1,3-butadiene is used as the conjugated diene compound (B), so-called butadiene rubber (BR) is obtained. When isoprene is used as the conjugated diene compound (B) and there is no structural unit of the aromatic vinyl compound (C), isoprene rubber (IR) is obtained. Among these, a styrene-butadiene rubber (SBR) structure is particularly preferred because it has excellent abrasion resistance, heat resistance, and aging resistance.

[0062] In the method for producing the modified conjugated diene copolymer of the present invention, the polymerization step and the terminal modification step can be carried out in the same manner as in the polymerization step and the terminal modification step of the modified vinyl aromatic copolymer described above. The polymerization initiator used in the polymerization step and the compound having a functional group used in the terminal modification step can also be the polymerization initiator and the compound having a functional group described above.

[0063] This polymerization or copolymerization of the conjugated diene compound (B) is preferably carried out by solution polymerization in an inert solvent. The polymerization solvent is not particularly limited, and hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons can be used. Specific examples include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, and decalin; and aromatic hydrocarbons such as benzene, toluene, and xylene, as well as hydrocarbon solvents consisting of mixtures thereof. The above-mentioned conjugated diene compounds and polymerization solvents, either alone or in mixtures thereof, are preferably treated with an organometallic compound. This allows the allenes and acetylenes contained in the conjugated diene compounds and polymerization solvent to be treated. As a result, a polymer having a high concentration of active terminals can be obtained, thereby achieving a high modification rate.

[0064] The polymerization temperature during the copolymerization of the conjugated diene compound (B) or the conjugated diene compound (B) with the aromatic vinyl compound (C) is not particularly limited as long as it is a temperature at which living anionic polymerization proceeds. However, from the viewpoint of productivity, it is preferably 0°C or higher. From the viewpoint of ensuring a sufficient amount of the modified vinyl aromatic copolymer having the structural unit (c) composed of the silane functional group represented by formula (2) and / or formula (3) of the present invention reacting with the active terminal after the polymerization is completed, it is preferably 120°C or lower. A more preferred temperature is 50 to 100°C. The polymerization method during the copolymerization of the conjugated diene compound (B) or the conjugated diene compound (B) with the aromatic vinyl compound (C) is not particularly limited, but can be a batch polymerization method (also referred to as a "batch method"), a continuous polymerization method, or the like. In a continuous method, one or two or more connected reactors can be used. The reactor can be a tank type or a tubular type equipped with a stirrer. In the batch process, the molecular weight distribution of the polymer obtained is generally narrow, with Mw / Mn tending to be 1.0 or more and less than 1.8, whereas in the continuous process, the molecular weight distribution is generally broad, with Mw / Mn tending to be 1.8 or more and less than 3.

[0065] The weight-average molecular weight (polystyrene equivalent) of the modified conjugated diene copolymer of the present invention is preferably 100,000 to 2,000,000, more preferably 150,000 to 1,000,000, taking into consideration processability and physical properties. The weight-average molecular weight can be determined by measuring a chromatogram using GPC with a column packed with polystyrene gel and then using a calibration curve using standard polystyrene. In the differential molecular weight distribution curve obtained by gel permeation chromatography (GPC), when the total area is taken as 100%, the area of ​​the region having a number-average molecular weight (Mn) three times or more (3 Mp or more) of the lowest molecular weight peak should be 20% or more. More preferably, it is 40% or more by area. Particularly preferably, it is 60% or more by area.

[0066] The modified conjugated diene copolymer of the present invention preferably contains 0.001 to 6 wt% of structural units (A1) derived from a modified vinyl aromatic copolymer, 29 to 99.999 wt% of structural units (B1) derived from a conjugated diene compound, and 0 to 70 wt% of structural units (C1) derived from an aromatic vinyl compound. The amount of structural units (A1) derived from the modified vinyl aromatic copolymer (A) is preferably 0.001 to 5 wt%, more preferably 0.005 to 5 wt%, even more preferably 0.01 to 5 wt%, and optimally 0.001 to 1 wt%. The amount of structural units (B1) derived from the conjugated diene compound (B) is 29 to 99.999 wt%, preferably 80 to 99.999 wt%, more preferably 90 to 99.995 wt%, and even more preferably 95 to 99.99 wt%. When an aromatic vinyl compound (C) is used, the content of the structural unit (A1) is the same as above, the content of the structural unit (B1) is 30 to 97.999 wt%, preferably 45 to 94.995 wt%, and more preferably 55 to 89.99 wt%, and the content of the structural unit (C1) derived from the aromatic vinyl compound (C) is 2 to 50 wt%, preferably 5 to 45 wt%, and more preferably 10 to 40 wt%.

[0067] The microstructure (cis, trans, vinyl bond content) of the modified conjugated diene copolymer can be arbitrarily changed by using a polar compound, etc., but the content of vinyl bonds (1,2-bonds) in the conjugated diene units before the terminals are modified is preferably 10 to 80 mol %. When the modified conjugated diene copolymer of the present invention is made into a resin composition described below and then crosslinked for use as an automobile tire, in order to achieve a high level of balance between rolling resistance performance and abrasion resistance, the content is preferably 20 to 75 mol %, more preferably 25 to 75 mol %, and even more preferably 25 to 70 mol %. Optimally, it is 25 to 45 mol %. In this case, the mass ratio of cis bonds to trans bonds in the conjugated diene bond units is preferably cis bonds / trans bonds = 1 / 1.1 to 1.5.

[0068] If necessary, a reaction terminator may be added to the polymer solution of the modified conjugated diene copolymer obtained by the above-mentioned polymerization method. Examples of the reaction terminator include alcohols such as methanol, ethanol, and propanol; organic acids such as stearic acid, lauric acid, and octanoic acid; and water.

[0069] After the polymerization reaction of the modified conjugated diene copolymer, metals contained in the polymer may be deashed, if necessary. For example, deashing may be performed by contacting the polymer solution with water, an organic acid, an inorganic acid, an oxidizing agent such as hydrogen peroxide, or the like to extract the metals, and then separating the aqueous layer.

[0070] When the modified conjugated diene polymer obtained as described above is obtained as a solution, an antioxidant and / or additives may be added as necessary, followed by removal of the solvent and drying by a conventional method. This allows the polymer to be used as a raw material for the resin composition described below. Specific examples include a method using steam stripping and dehydration drying, and a direct desiccation method using a drum dryer, flashing, and a vent extruder.

[0071] The antioxidant is not particularly limited, and known antioxidants can be used. Examples of antioxidants include phenol-based stabilizers, phosphorus-based stabilizers, and sulfur-based stabilizers. Specific examples include 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol, among others.

[0072] If necessary, additives such as water, alcohols such as methanol, ethanol, and isopropanol, carboxylic acids such as stearic acid, oleic acid, myristic acid, lauric acid, decanoic acid, citric acid, and malic acid, aqueous inorganic acids, and carbon dioxide gas may be added to remove or neutralize ionic substances.

[0073] The resin composition of the present invention contains 100 parts by mass of raw rubber containing 20 parts by mass or more of a modified conjugated diene polymer, and 5 to 200 parts by mass of a filler.

[0074] The content of the modified conjugated diene polymer per 100 parts by mass of raw rubber is 20 parts by mass or more, preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more. When the content is 20 parts by mass or more, the filler dispersibility aimed at by the present invention is excellent, and when the resin composition of this embodiment is vulcanized, performance such as tensile properties and viscoelastic properties is excellent. When used as a tire material, the tire can achieve excellent fuel economy, grip performance, abrasion resistance, and rigidity. Furthermore, the content of the modified conjugated diene polymer is preferably 90 parts by mass or less, more preferably 80 parts by mass or less. By keeping the content at 90 parts by mass or less, the Mooney viscosity of the unvulcanized resin composition of the present invention is reduced, thereby improving processability.

[0075] The raw material rubber other than the modified conjugated diene polymer is not particularly limited, and examples thereof include a conjugated diene polymer or a hydrogenated product thereof, a random copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof, a block copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof, other conjugated diene copolymers or a hydrogenated product thereof, a non-diene polymer, and natural rubber.

[0076] Specific examples of the conjugated diene polymer or its hydrogenated product are not particularly limited, and include, for example, butadiene rubber or its hydrogenated product, isoprene rubber or its hydrogenated product, and the like.

[0077] Specific examples of the random copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof include, but are not limited to, styrene-butadiene copolymer rubber or a hydrogenated product thereof.

[0078] Specific examples of the block copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof are not particularly limited, and include, for example, styrene-based elastomers such as a styrene-butadiene block copolymer or a hydrogenated product thereof, and a styrene-isoprene block copolymer or a hydrogenated product thereof.

[0079] Specific examples of other conjugated diene copolymers or hydrogenated products thereof are not particularly limited, and include, for example, acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0080] The non-diene polymer is not particularly limited, and examples thereof include olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0081] In the present invention, when the modified conjugated diene polymer is a modified styrene-butadiene rubber, the other rubber is preferably polybutadiene, and when the modified butadiene polymer is a modified polybutadiene, the other rubber is preferably natural rubber or polyisoprene rubber.

[0082] The weight-average molecular weight of the various rubbery polymers described above is preferably 2,000 to 2,000,000, more preferably 5,000 to 1,500,000, from the viewpoint of a balance between performance and processing characteristics. Low-molecular-weight so-called liquid rubbers can also be used. These rubbery polymers may be used alone or in combination of two or more. The weight-average molecular weight referred to here is the weight-average molecular weight (Mw) in terms of polystyrene obtained by gel permeation chromatography (GPC) measurement.

[0083] The amount of filler used relative to the raw rubber increases with increasing filler content, and is adjusted to achieve the desired physical properties depending on the application. Within this range, the filler is well dispersed and processable. For tire applications, the filler content is preferably 5 to 150 parts by mass, and for footwear applications, the filler content is preferably 30 to 200 parts by mass. Within the range of this embodiment, a wide range of fillers can be used, from soft to hard.

[0084] The resin composition of the present invention contains 0.5 to 200 parts by mass of at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, per 100 parts by mass of raw rubber.

[0085] The silica-based inorganic filler contained in the resin composition is, for example, SiO ２ Alternatively, it is preferable to use solid particles containing silicate as the main component of the structural unit. Here, the main component means a component that accounts for 50% by mass or more of the total, preferably a component that accounts for 70% by mass or more, and more preferably a component that accounts for 90% by mass or more.

[0086] Specific examples of silica-based inorganic fillers include inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Silica-based inorganic fillers may be used alone or in combination of two or more. Silica-based inorganic fillers with hydrophobic surfaces and mixtures of silica-based inorganic fillers and non-silica-based inorganic fillers may also be used. Among these, silica and glass fiber are preferred, and silica is more preferred.

[0087] As the silica, dry silica, wet silica, synthetic silicate silica, etc. can be used, but among them, wet silica is preferred because it is superior in both improving the fracture properties and wet skid resistance performance. As the silica, silica having a BET specific surface area of ​​50 to 500 m ２ / g of silica is used. By blending such silica, excellent fuel economy, abrasion resistance, wet skid performance and handling stability can be obtained. In addition, silica with a high specific surface area, i.e., fine particle silica, can also be used and dispersed well. As the fine particle silica, CTAB (cetyltrimethylammonium bromide) with a specific surface area of ​​180 m is used. ２ / g or more, BET specific surface area is 185m ２ / g or more of silica. The average primary particle diameter is, for example, 25 nm or less. By blending such fine particle silica, the resin composition of this embodiment can achieve excellent fuel economy, abrasion resistance, wet skid performance, and handling stability.

[0088] The aggregate size of the fine-particle silica is not particularly limited and can be 30 nm or more. By having such an aggregate size, excellent reinforcement, fuel economy, abrasion resistance, wet skid performance, and handling stability can be achieved while maintaining good dispersibility. The aggregate size is also called the agglomerate size or the maximum frequency Stokes equivalent diameter, and corresponds to the particle size when a silica aggregate composed of a plurality of primary particles connected together is considered as a single particle. The aggregate size can be measured, for example, using a disk centrifugal sedimentation particle size distribution analyzer such as the BI-XDC (manufactured by Brookhaven Instruments Corporation). Specifically, it can be measured by the method described in JP 2011-132307 A. The average primary particle size of the fine-particle silica is not particularly limited and is preferably 25 nm or less.

[0089] The amount of the fine particle silica in the resin composition of the present invention is not particularly limited, and is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, per 100 parts by mass of the rubber component. If the amount is 5 parts by mass or more, the effect of adding the fine particle silica can be fully obtained. The amount of the fine particle silica is 200 parts by mass or less, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less. If the amount is 200 parts by mass or less, substantially good processability can be obtained.

[0090] The resin composition of the present invention preferably further contains a reinforcing filler having a BET specific surface area of ​​185 m ２ The resin composition contains 5 to 100 parts by mass of silica or carbon black in an amount of less than 1 / g.

[0091] In the resin composition of the present invention, a reinforcing filler having a BET nitrogen adsorption specific surface area (N2SA) of 185 m ２ Silica having a viscosity of less than 150 m / g is preferably used, and more preferably less than 150 m / g. ２ / g of silica is used, preferably 50 m ２In this range, a good balance between reinforcing properties and dispersibility is achieved. Also, particles with an appropriate particle size are used depending on the application.

[0092] Carbon black is classified into N110, N220, N330, N339, N550, N660, etc. according to the ASTM classification of carbon black for rubber, and is selected depending on the application. By using carbon black in combination, it is possible to enhance reinforcing properties and improve dry grip performance when used in tire tread applications. The carbon black preferably has a BET nitrogen adsorption specific surface area (N2SA) of 185 m ２ / g or less, and preferably 30m ２ / g or more, more preferably 50 to 130m ２ / g. In this range, a good balance between reinforcing properties and dispersibility is obtained. When used for tire tread applications, N220, N330, and N339 are more preferable.

[0093] Furthermore, in the resin composition of the present invention, in addition to the silica described above, other reinforcing fillers can be used. The other reinforcing fillers are not particularly limited, but the metal oxide used as the reinforcing filler is preferably solid particles whose main component is represented by the chemical formula MxOy (M represents a metal atom, and x and y each represent an integer of 1 to 6). Here, the term "main component" refers to a component that accounts for 50% by mass or more of the total, preferably a component that accounts for 70% by mass or more, and more preferably a component that accounts for 90% by mass or more. Examples of metal oxides that can be used include alumina, titanium oxide, magnesium oxide, and zinc oxide. Examples of metal hydroxides that can be used as reinforcing fillers include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide. The metal oxides and metal hydroxides described above as other reinforcing fillers may be used alone or in combination of two or more. Mixtures with other inorganic fillers can also be used.

[0094] A silane coupling agent may be used in the resin composition of the present invention. The silane coupling agent is not particularly limited, but may be, for example, a compound having both a silica affinity moiety and a polymer affinity moiety in the molecule, such as a sulfide compound, a mercapto compound, a vinyl compound, an amino compound, a glycidoxy compound, a nitro compound, or a chloro compound. Examples of sulfide compounds include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylsilyl. Examples of the mercapto compounds include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltriethoxysilane, and the like. Examples of the mercapto compounds include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltriethoxysilane, and the like. Examples of the vinyl compounds include vinyltriethoxysilane and vinyltrimethoxysilane. Examples of amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.Examples of glycidoxy compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. Examples of nitro compounds include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane. Examples of chloro compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. Other compounds include octyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0095] These silane coupling agents may be used alone or in combination of two or more. Among these silane coupling agents, sulfur-containing silane coupling agents such as sulfide compounds and mercapto compounds are preferred from the viewpoint of a greater reinforcing effect, with bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and 3-mercaptopropyltrimethoxysilane being more preferred. The amount of silane coupling agent blended is 1 to 20 parts by mass, preferably 2 to 15 parts by mass, per 100 parts by mass of silica. Blending the silane coupling agent within this range further improves the dispersibility of silica, improves processability, and further improves the performance of the vulcanized rubber, such as improving abrasion resistance.

[0096] In the resin composition of the present invention, the hardness and modulus can be adjusted by using a plasticizer. The plasticizer is not particularly limited, but for example, the same oil as the extender oil described above can be used. In addition, various natural oils, synthetic oils, low molecular weight polymers, etc. can also be used. Known processing aids can also be used.

[0097] The resin composition of the present invention may be further subjected to a crosslinking treatment by adding a vulcanizing agent (crosslinking agent), compounding agents, etc. to form a resin composition. Examples of such crosslinking agents include, but are not limited to, sulfur-based vulcanizing agents, organic peroxides, etc. Examples of sulfur-based vulcanizing agents include, but are not limited to, sulfur, morpholine disulfide, etc. Examples of organic peroxides include, but are not limited to, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, and cumene hydroperoxide. The amount of vulcanizing agent used is not particularly limited, but is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, per 100 parts by mass of the conjugated diene copolymer. Conventional vulcanization methods can be used, and the vulcanization temperature is, for example, preferably 120°C to 200°C, more preferably 140°C to 180°C. If necessary, a vulcanization accelerator or vulcanization aid may be blended. The vulcanization accelerator is not particularly limited, but for example, one containing at least one of sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators can be used.

[0098] Furthermore, if necessary, a vulcanization aid may be blended, and the vulcanization aid is not particularly limited, but examples thereof include zinc oxide, stearic acid, etc. Furthermore, an antioxidant may be used.

[0099] The resin composition of the present invention can be produced by mixing the above-mentioned components. The method for mixing the modified conjugated diene copolymer with at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, and, optionally, a silane coupling agent, is not particularly limited. Examples include melt-kneading methods using common mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, and multi-screw extruders, and methods in which the components are dissolved and mixed and then the solvent is removed by heating. Of these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the standpoints of productivity and good kneading ability. Furthermore, either a method in which the rubber component and various compounding ingredients are kneaded all at once or a method in which they are mixed in multiple batches can be used.

[0100] In the present invention, the degree of polymer concentration ability on the filler surface can be expressed by the amount of bound rubber (bound rubber generation ability) of the modified conjugated diene polymer at 25° C. The amount of bound rubber in the resin composition after completion of the above-mentioned kneading is preferably 15% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving abrasion resistance and breaking strength.

[0101] The resin composition may be vulcanized with a vulcanizing agent to form a vulcanized composition. Examples of the vulcanizing agent include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds.

[0102] During vulcanization, a vulcanization accelerator may be used as needed. Conventionally known vulcanization accelerators can be used, including sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Zinc oxide, stearic acid, and the like can be used as vulcanization aids.

[0103] The resin composition of the present invention may contain a rubber softener to improve processability. Suitable rubber softeners include mineral oils, liquids, and low-molecular-weight synthetic softeners.

[0104] Mineral oil-based rubber softeners known as process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthenic rings, and paraffin chains, with those in which the number of carbon atoms in the paraffin chains accounts for 50% or more of the total carbon atoms being called paraffinic, those in which the number of carbon atoms in the naphthenic rings is 30 to 45% being naphthenic, and those in which the number of aromatic carbon atoms is more than 30% being aromatic. The rubber softener used in this embodiment is preferably naphthenic and / or paraffinic.

[0105] The amount of the rubber softener to be added is not particularly limited, but is preferably 10 to 80 parts by mass, more preferably 20 to 50 parts by mass, per 100 parts by mass of the conjugated diene copolymer.

[0106] The resin composition of the present invention may contain various additives such as softeners and fillers other than those described above, as well as heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, within the scope of the present embodiment. Specific examples of fillers include calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Examples of softeners that are added as needed to adjust the hardness and fluidity of the target product include liquid paraffin, castor oil, and linseed oil. Known materials can be used as the heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0107] The cross-linked resin product of the present invention is obtained by cross-linking a resin composition. For example, a tire can be manufactured by extruding the resin composition according to the tire shape (e.g., tread shape), heating and pressurizing the extrusion in a vulcanizer to produce a tread, and assembling the tread with other components.

[0108] The resin composition of the present invention, when formed into a resin cross-linked product, has excellent mechanical strength and abrasion resistance. Therefore, as described above, it can be suitably applied to structural components such as treads and sidewall members of tires such as fuel-efficient tires, large tires, and high-performance tires. In addition to structural components, it can also be suitably used for rubber belts, rubber hoses, footwear materials, etc.

[0109] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In each example, all parts are by weight unless otherwise specified, and the physical properties were evaluated by the methods shown below.

[0110] 1) Molecular weight and molecular weight distribution, area (%) of multi-branched components, and area (%) of 3 Mp or more. The molecular weight and molecular weight distribution were measured using GPC (HLC-8220GPC, manufactured by Tosoh Corporation) and a TSKgel Multipore H (manufactured by Tosoh Corporation) as the analytical column. ＸＬ -M: 2 tubes, TSKgel G1000H ＸＬ The analysis was performed using one column of a modified conjugated diene copolymer, one TSKguard column MP (XL) as a guard column, tetrahydrofuran (THF) as a solvent, a flow rate of 1.0 ml / min, a column temperature of 38 ° C, and a calibration curve based on monodisperse polystyrene. Furthermore, as shown in Figure 1, the area (%) of the multi-branched component of the modified conjugated diene copolymer indicates the area % of the molecular weight range of at least twice the peak top molecular weight (Mp) of the uncoupled, unbranched diene copolymer. Furthermore, the area (%) of at least 3 Mp indicates the area % of the molecular weight range of at least three times the peak top molecular weight (Mp) of the uncoupled, unbranched diene copolymer.

[0111] 2) Structure of modified vinyl aromatic copolymer Using a JEOL JNM-LA600 nuclear magnetic resonance spectrometer, １３ C-NMR and １ The results were determined by H-NMR analysis. １The resonance line of tetramethylsilane was used as an internal standard. 3) Solvent-soluble (cyclohexane) 5.0 g of the modified vinyl aromatic copolymer was dissolved in 95.0 g of cyclohexane and filtered through a glass filter. The filtered glass filter was washed with 30 g of cyclohexane and vacuum-dried at 60° C. The weight of the polymer content on the filter was calculated, and a dry weight of the polymer content of less than 0.025 g was evaluated as ◯, a dry weight of 0.025 g or more but less than 0.25 g was evaluated as △, and a dry weight of 0.25 g or more was evaluated as ×.

[0112] 4) Mooney viscosity: Measured according to JIS K6300-1 using an L-shaped rotor, preheating for 1 minute, rotor operation time for 4 minutes, and a temperature of 100°C. 5) Gel content: 0.5 g of copolymer rubber was dissolved in 100 mL of toluene, to which 1.0 g of a 0.2 wt% Sudan III toluene solution was added and allowed to stand for 1 hour. This sample solution was filtered through a 0.2 μm PTFE membrane filter, and the membrane filter was vacuum dried at 40°C. After drying, the gel content colored with Sudan III on the membrane filter was visually observed; 0 gels were marked with a circle, 1 to 5 gels with a triangle, and 6 or more gels with an x.

[0113] 6) Thermogravimetry (TGA) was carried out in accordance with JIS K7120, and the weight loss at 350°C (TGA) ３５０ ) was sought.

[0114] 7) Haze A sample prepared by dissolving 0.5 g of copolymer rubber in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., SZ-Σ90) with toluene as the reference sample.

[0115] 8) Content of vinyl bonds in conjugated diene copolymer (SBR) A sample was prepared as a carbon disulfide solution, and its infrared spectrum was measured in the range of 600 to 1000 cm-1 using a solution cell. The amount of vinyl bonds (%) in the conjugated diene copolymer (SBR) was calculated from the absorbance at a predetermined wave number according to the calculation formula of the Hampton method (styrene-butadiene copolymer). The instrument used was a Spectrum 100 manufactured by PerkinElmer.

[0116] 9) Bound Rubber Amount After kneading, 0.4 g of unvulcanized rubber was cut into 2 mm squares and placed in a sample tube with 50 mL of toluene. The mixture was then left to stand at room temperature for 48 hours. The mixture was then extracted using a glass filter, and the toluene solution and rubber portions were dried separately. The weight of the rubber portion on the filter was calculated and used as the bound rubber amount. The dried toluene solution portion was then dissolved in chloroform, and the proportion of polybutadiene was calculated using proton NMR. This value was used to calculate back from the actual blended parts to determine the bound rubber amount of polybutadiene. The bound rubber amount in Comparative Example 3 was expressed as an index, with the bound rubber amount in Comparative Example 3 being 100.

[0117] 10) Tensile strength The 300% modulus was measured according to the tensile test method of JIS K6251, and the measured value of the crosslinked rubber obtained in Comparative Example 3 was set to 100, and the resulting value was indexed. A larger index value indicates better tensile strength.

[0118] 11) Abrasion Resistance A method using a Lambourn abrasion tester in accordance with JIS K6264 was used to measure the amount of abrasion at a slip ratio of 25%, and the measured value for the crosslinked rubber obtained in Comparative Example 3 was set to 100, and the measured value was indexed. The measurement temperature was room temperature. The larger the index value, the better the abrasion resistance.

[0119] The raw materials used in the examples or their abbreviations are as follows: DVB-810: a mixture of divinylbenzene and ethylvinylbenzene components; divinylbenzene content 81.0 wt%, manufactured by Nippon Steel Chemical & Material Co., Ltd.

[0120] Example 1 Synthesis of Modified Vinyl Aromatic Copolymer (A-1) 270 ml (210.3 g) of ethylcyclohexane and 1.35 ml (7.0 mmol) of the cocatalyst 2,2-di(2-tetrahydrofuryl)propane were charged, and 21.9 ml of an n-hexane solution containing 2.24 g (35.0 mmol) of n-butyllithium (structural formula shown below) in pure form was added at 30°C. A solution of 2.77 g (17.5 mmol) of 1,3-diisopropenylbenzene (structural formula below), from which impurities had been removed in advance, dissolved in 40 ml (31.2 g) of ethylcyclohexane was added over 1 hour, and stirring was continued at 30° C. for 30 minutes. Next, a solution of 25.5 g (0.245 mol) of styrene (structural formula below) dissolved in 10 ml (7.8 g) of ethylcyclohexane was added over 30 minutes to initiate the first stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 67°C. After completion of the polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. Next, 7.15 g (105 mmol) of isoprene (structural formula below) was added to the reactor as an additional monomer, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small amount of the polymerization solution was sampled and analyzed by GC. No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 1940, an Mw of 2410, and an Mw / Mn of 1.24. Next, 8.73 g (35.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 8.27 g (70.0 mmol) of a neutralizing agent, succinic acid, was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the structural formula below. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 41.74 g (yield: 98.0 wt%) of modified vinyl aromatic copolymer A-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer A-1 are shown in Table 1.

[0121] The resulting modified vinyl aromatic copolymer A-1 had an Mn of 2940, an Mw of 4140, and an Mw / Mn ratio of 1.41. １３ C-NMR and １ By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer A-1 contained 4.35 mol% (6.50 wt%) of structural units derived from diisopropenylbenzene, 60.87 mol% (59.91 wt%) of structural units derived from styrene, 26.09 mol% (16.79 wt%) of structural units derived from isoprene, and 8.70 mol% (16.79 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and that 2.42 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 4.22 mol% (6.31 wt%), and the degree of polyfunctional structure (e1 / c) was 0.97. In formula (1), R1 is phenyl, R2 is methyl, and R3 is n-pentyl. The amount of diisopropenylbenzene-derived structural units having residual vinyl groups contained in the modified vinyl aromatic copolymer (A-1) was 1.31 mol % (1.92 wt %). The amount of modifier bonded to isoprene-derived units was 93.6 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (A-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.02.

[0122] Comparative Example 1 Synthesis of Modified Vinyl Aromatic Copolymer (B-1) 4.37 mol (630.2 mL) of divinylbenzene (a mixture of 1,4-divinylbenzene and 1,3-divinylbenzene; the same applies to the following examples), 3.34 mol (457.5 mL) of ethylvinylbenzene (a mixture of 1-ethyl-4-vinylbenzene and 1-ethyl-3-vinylbenzene; the same applies to the following examples), 6.90 mol (749.9 mL) of anisole (structural formula below), and 345 mL of toluene were placed in a 3.0 L reactor, and 103.5 mmol (13.0 mL) of a boron trifluoride diethyl ether complex was added at 50° C., followed by reaction for 5 hours. After the polymerization solution was terminated with an aqueous sodium hydrogen carbonate solution, the oil layer was washed three times with pure water and the polymer was recovered by devolatilization under reduced pressure at 60° C. The obtained polymer was weighed, and it was confirmed that 945.3 g of copolymer B-1 was obtained.

[0123] The resulting copolymer B-1 had Mn of 624, Mw of 2360, and Mw / Mn of 3.79, and was a random copolymer. １３ C-NMR and １ By performing H-NMR analysis, the NMR chart of copolymer B-1 showed resonance lines of terminal groups in which an anisole-derived benzene ring was bonded to the main chain end. The amount of anisole-derived structural units incorporated into the soluble polyfunctional vinyl aromatic polymer, calculated from the elemental analysis results and the number-average molecular weight converted to standard polystyrene, was 1.6 (units / molecule). Furthermore, it contained 61.3 mol% of divinylbenzene-derived structural units and a total of 38.7 mol% of ethylvinylbenzene-derived structural units (excluding terminal structural units). The vinyl group content in copolymer B-1 was 34.8 mol% (excluding terminal structural units). Furthermore, no polyfunctional structural units (e1) having multiple organic groups derived from the organic alkali metal compound represented by formula (1) were observed. Furthermore, TMA measurement of the cured product showed no clear Tg, and the softening temperature was 300°C or higher. TGA measurement showed a weight loss of 3.70 wt% at 350°C, and heat discoloration resistance was good. Copolymer B-1 was soluble in toluene, xylene, THF, dichloroethane, dichloromethane and chloroform, and no gel formation was observed.

[0124] Comparative Example 2 Synthesis of Polysiloxane-Modified Crosslinked Polymer Particles (C-1) 45 parts of divinylbenzene (purity 56%, the remaining 38% was ethylvinylbenzene, the remaining 6% was impurities, hereinafter this divinylbenzene was used), 55 parts of styrene, 3 parts of sodium dodecylbenzenesulfonate, 0.5 parts of polyvinyl alcohol, 1000 parts of ion-exchanged water, and 0.7 parts of α,α'-azoisobutyronitrile were charged into a reaction vessel and stirred at 15,000 rpm for 60 minutes with a homomixer to make it uniform. Next, the mixture was heated to 80 ° C. while blowing in nitrogen gas, and stirring was continued for 3 hours to carry out suspension polymerization, to obtain polymer particles (C-0). Next, the pH was adjusted to 8.0 while maintaining the temperature of the reaction vessel at 25 ° C., and 30 parts of methyltriethoxysilane (MTES: structural formula below) were added and stirred vigorously for about 30 minutes. The reaction vessel was then heated to 70°C and reacted for 3 hours to complete the condensation reaction, producing crosslinked polymer particles C-1. No coagulation was observed in this dispersion. The average particle size of the resulting crosslinked polymer particles a was measured and found to be 1.9 µm. The aqueous slurry of the resulting crosslinked polymer particles was centrifuged and washed, and then subjected to elemental analysis by ESCA, revealing the presence of Si element.

[0125] Example 2 Synthesis of Modified Vinyl Aromatic Copolymer (D-1) 270 ml (210.3 g) of ethylcyclohexane and 1.35 ml (7.0 mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and 21.9 ml of an n-hexane solution containing 2.24 g (35.0 mmol) of pure n-butyllithium was added at 30° C., followed by the addition of a solution of 2.82 g (17.5 mmol of divinylbenzene (a mixture of m- and p-isomers) and 4.16 mmol of ethylvinylbenzene (a mixture of m- and p-isomers)) of DVB-810 (the structural formulas of divinylbenzene and ethylvinylbenzene are shown below), from which impurities had been removed, dissolved in 40 ml (31.2 g) of ethylcyclohexane over 1 hour. Stirring was continued at 30° C. for 30 minutes. Next, a solution of 25.5 g (0.245 mol) of styrene dissolved in 10 ml (7.8 g) of ethylcyclohexane was added over 30 minutes to initiate the first-stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 62°C. After completion of the polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, confirming that the polymerization conversion was nearly 100%. Next, 7.15 g (105 mmol) of isoprene was added to the reactor as an additional monomer, and the second-stage polymerization was initiated at 30°C. After completion of the second-stage polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by GC. No unreacted monomer was observed, confirming that the polymerization conversion was nearly 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 1970, an Mw of 2630, and an Mw / Mn of 1.34. Next, 8.73 g (35.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the resulting mixture was subjected to a modification reaction for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 8.27 g (70.0 mmol) of succinic acid was added, stirred, and then filtered. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane. No gel or microgel formation was observed. As a result, 38.51 g (yield: 96.7 wt%) of modified vinyl aromatic copolymer D-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer D-1 are shown in Table 1.

[0126] The resulting modified vinyl aromatic copolymer D-1 had an Mn of 2650, an Mw of 3910, and an Mw / Mn ratio of 1.48. １３ C-NMR and １By performing H-NMR analysis, the modified vinyl aromatic copolymer D-1 contained 4.50 mol% (5.34 wt%) of structural units derived from divinylbenzene, 1.03 mol% (1.27 wt%) of structural units derived from ethylvinylbenzene, 60.25 mol% (59.84 wt%) of structural units derived from styrene, 25.82 mol% (16.77 wt%) of structural units derived from isoprene, and 8.61 mol% (16.77 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and it was confirmed that 2.33 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The content of the polyfunctional structural unit (e1) represented by the formula (1) was 3.33 mol% (3.95 wt%), and the polyfunctional structure degree (e1 / c) was 0.74. In formula (1), R1 is phenyl, R2 is hydrogen, and R3 is n-pentyl. The content of divinylbenzene-derived structural units having residual vinyl groups contained in the modified vinyl aromatic copolymer (D-1) was 1.82 mol % (0.21 wt %). The modifier bonded to isoprene-derived units was 89.3 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (D-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.06.

[0127] Example 3 Synthesis of Modified Vinyl Aromatic Copolymer (E-1) 270 ml (210.3 g) of ethylcyclohexane and 1.35 ml (7.0 mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and 21.9 ml of an n-hexane solution containing 2.24 g (35.0 mmol) of pure n-butyllithium was added at 30°C. Then, a solution of 2.77 g (17.5 mmol) of 1,3-diisopropenylbenzene, from which impurities had been removed, dissolved in 40 ml (31.2 g) of ethylcyclohexane was added over 1 hour. Stirring was continued at 30°C for 30 minutes. Next, a solution of 25.5 g (0.245 mol) of styrene dissolved in 10 ml (7.8 g) of ethylcyclohexane was added over 30 minutes, initiating the first-stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 64°C. After the polymerization reaction was completed, a small sample of the polymerization solution was taken and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. Next, 7.15 g (105 mmol) of isoprene was added to the reactor as an additional monomer, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small sample of the polymerization solution was taken and analyzed by GC. No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. GPC analysis revealed that the copolymer at the time of completing the second-stage polymerization had an Mn of 2010, an Mw of 2490, and an Mw / Mn of 1.24. Next, 9.74 g (35.0 mmol) of 3-glycidoxypropyltriethoxysilane (GPTES) represented by the following structural formula was added as a modifier, and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 8.27 g (70.0 mmol) of succinic acid was added, stirred, and then filtered. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 42.89 g (yield: 97.6 wt%) of modified vinyl aromatic copolymer E-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer E-1 are shown in Table 1.

[0128] The resulting modified vinyl aromatic copolymer E-1 had an Mn of 3170, an Mw of 4600, and an Mw / Mn ratio of 1.45. １３ C-NMR and １ By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer E-1 contained 4.35 mol% (6.30 wt%) of structural units derived from diisopropenylbenzene, 60.87 mol% (58.07 wt%) of structural units derived from styrene, 26.09 mol% (16.28 wt%) of structural units derived from isoprene, and 8.70 mol% (19.35 wt%) of structural units derived from 3-glycidoxypropyltriethoxysilane (GPTES), and that 2.53 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The content of the polyfunctional structural unit (e1) represented by the formula (1) was 4.26 mol% (6.17 wt%), and the degree of polyfunctional structure (e1 / c) was 0.98. In formula (1), R1 is phenyl, R2 is methyl, and R3 is n-pentyl. The content of structural units derived from diisopropenylbenzene having residual vinyl groups contained in the modified vinyl aromatic copolymer (A-1) was 0.94 mol % (1.32 wt %). The content of the modifier bonded to the isoprene-derived units was 94.2 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (E-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.03.

[0129] The analytical results of the copolymers of Examples 1, 2 and 3 and Comparative Examples 1 and 2 are shown in Table 1.

[0130] Example 4 Synthesis of Modified Conjugated Diene Copolymer (A-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene, from which impurities had been removed, to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 73°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.487 g of the modified vinyl aromatic copolymer (A-1) obtained in Example 1 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) A-2 was obtained. The analytical results of the modified conjugated diene copolymer A-2 are shown in Table 2.

[0131] Comparative Example 3 Synthesis of Modified Conjugated Diene Copolymer (B-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 79°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.379 g of the modified vinyl aromatic copolymer (B-1) obtained in Comparative Example 1 as an SBR modifier was added, and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer B-2 was obtained. The analytical results of modified conjugated diene copolymer (modified SBR) B-2 are shown in Table 2.

[0132] Comparative Example 4 Synthesis of Modified Conjugated Diene Copolymer (C-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 79°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.466 g of the modified vinyl aromatic copolymer (C-1) obtained in Comparative Example 2 as an SBR modifier was added, and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer C-2 was obtained. The analytical results of modified conjugated diene copolymer (modified SBR) C-2 are shown in Table 2.

[0133] Example 5 Synthesis of Modified Conjugated Diene Copolymer (D-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene, from which impurities had been removed, to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 75°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.455 g of the modified vinyl aromatic copolymer (D-1) obtained in Example 2 as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR) was added, and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer D-2 was obtained. The analytical results of modified conjugated diene copolymer (modified SBR) D-2 are shown in Table 2.

[0134] Example 6 Synthesis of Modified Conjugated Diene Copolymer (E-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 81°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.502 g of the modified vinyl aromatic copolymer (E-1) obtained in Example 3 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer E-2 was obtained. The analytical results of modified conjugated diene copolymer (modified SBR) E-2 are shown in Table 2.

[0135]

[0136] Example 7 The modified conjugated diene copolymer (modified SBR) A-2 obtained in Example 4, process oil, carbon black, zinc oxide, stearic acid, and antioxidant were blended and kneaded for 4 minutes at 155°C and 60 rpm using a Labo Plastomill. Sulfur and a vulcanization accelerator were added to the resulting kneaded mixture, and the mixture was kneaded for 1 minute at 70°C and 60 rpm using a Labo Plastomill, followed by vulcanization to obtain crosslinked rubber A-3. The blending ratio of each additive is shown in Table 3, and the physical properties of the resulting crosslinked rubber are shown in Table 4.

[0137]

[0138] The additives used are as follows: Silica: ULTRASIL 7000 manufactured by Evonik Degussa; Carbon black: Nitelon #200IS manufactured by Shin-Nichika Carbon; Zinc oxide: Zinc oxide type 2 manufactured by Sakai Chemical Industry; Stearic acid: Fujifilm Wako Pure Chemical Industries; Anti-aging agent: Nocrac 6C manufactured by Ouchi Shinko Chemical Industry; Sulfur: Powdered sulfur JIS type 2 manufactured by Tsurumi Chemical Industry; Vulcanization accelerator A: Noccela CZ-G manufactured by Ouchi Shinko Chemical Industry; Vulcanization accelerator B: Noccela DP manufactured by Ouchi Shinko Chemical Industry.

[0139] Examples 8 and 9, Comparative Examples 5 and 6 Crosslinked rubbers B-3, C-3, D-3 and E-3 were obtained in the same manner as in Example 7, except that the modified conjugated diene copolymers (modified SBR) B-2, C-2, D-2 and E-2 synthesized in Examples 5 and 6 or Comparative Examples 3 and 4 were used instead of the modified conjugated diene copolymer (modified SBR) A-2. The physical properties of the obtained crosslinked rubbers are shown in Table 4.

[0140]

[0141] Example 10 Synthesis of Modified Vinyl Aromatic Copolymer (F-1) 270 ml (210.3 g) of cyclohexane and 5.08 ml (35.0 mmol) of the co-catalyst triethylamine were charged, and 21.9 ml of an n-hexane solution containing 2.24 g (35.0 mmol) of pure sec-butyllithium (structural formula shown below) was added at 30°C. A solution of 2.77 g (17.5 mmol) of 1,3-diisopropenylbenzene (structural formula below), from which impurities had been removed in advance, dissolved in 40 ml (31.2 g) of cyclohexane was added over 3 hours, and stirring was continued at 30° C. for 2 hours. Next, a solution of 25.5 g (0.245 mol) of styrene (structural formula below) dissolved in 10 ml (7.8 g) of cyclohexane was added over 30 minutes to initiate the first stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 62°C. After completion of the polymerization reaction, a small sample of the polymerization solution was taken and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. Next, 7.15 g (105 mmol) of isoprene (structural formula below) was added to the reactor as an additional monomer over 15 minutes, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small amount of the polymerization solution was sampled and analyzed by GC. No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was nearly 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 1870, an Mw of 2410, and an Mw / Mn of 1.29. Next, 8.73 g (35.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 8.27 g (70.0 mmol) of a neutralizing agent, succinic acid, was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the following structural formula: The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 41.31 g (yield: 97.0 wt%) of modified vinyl aromatic copolymer F-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer F-1 are shown in Table 5.

[0142] The resulting modified vinyl aromatic copolymer F-1 had an Mn of 2760, an Mw of 4080, and an Mw / Mn ratio of 1.48. １３ C-NMR and １By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer F-1 contained 4.35 mol% (6.50 wt%) of structural units derived from diisopropenylbenzene, 60.87 mol% (59.91 wt%) of structural units derived from styrene, 26.09 mol% (16.79 wt%) of structural units derived from isoprene, and 8.70 mol% (16.79 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and that 2.27 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 4.18 mol% (6.24 wt%), and the initiator-derived polyfunctional structure degree (e1 / c) was 0.96. In formula (1), R1 is phenyl, R2 is methyl, and R3 is 2-methylbutyl. The amount of diisopropenylbenzene-derived structural units having residual vinyl groups contained in the modified vinyl aromatic copolymer (F-1) was 0.17 mol % (0.26 wt %). The amount of modifier bonded to isoprene-derived units was 94.2 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (F-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.01.

[0143] Example 11 Synthesis of Modified Vinyl Aromatic Copolymer (G-1) 100 ml (77.9 g) of cyclohexane and 6.68 ml (46.0 mmol) of the co-catalyst triethylamine were charged, and 35.38 ml of an n-hexane solution containing 2.95 g (46.0 mmol) of pure sec-butyllithium (structural formula shown below) was added at 30°C. A solution of 3.10 g (23.0 mmol of divinylbenzene (a mixture of m- and p-isomers) and 0.77 mmol of ethylvinylbenzene (a mixture of m- and p-isomers) of DVB-960 (the structural formulas of divinylbenzene and ethylvinylbenzene are shown below), from which impurities had been removed in advance, dissolved in 90.7 ml (70.7 g) of cyclohexane was added over 2 hours. Stirring was continued at 30°C for 1 hour. Next, 33.5 g (0.322 mol) of styrene (structural formula below) was added over 30 minutes to initiate the first stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 59°C. After completion of the polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. Next, 9.40 g (138 mmol) of isoprene (structural formula below) was added as an additional monomer to the reactor over 30 minutes, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small amount of the polymerization solution was sampled and subjected to GC analysis. No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was nearly 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 2610, an Mw of 3260, and an Mw / Mn of 1.25. Next, 11.47 g (46.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 10.86 g (92.0 mmol) of the neutralizing agent succinic acid was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the following structural formula. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 53.12 g (yield: 96.0 wt%) of modified vinyl aromatic copolymer G-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer G-1 are shown in Table 5.

[0144] The resulting modified vinyl aromatic copolymer G-1 had an Mn of 2740, an Mw of 4750, and an Mw / Mn ratio of 1.73. １３ C-NMR and １ By performing H-NMR analysis, the modified vinyl aromatic copolymer G-1 contained 4.34 mol% (5.40 wt%) of structural units derived from divinylbenzene, 0.15 mol% (0.18 wt%) of structural units derived from ethylvinylbenzene, 60.78 mol% (60.50 wt%) of structural units derived from styrene, 26.05 mol% (16.95 wt%) of structural units derived from isoprene, and 8.68 mol% (16.96 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and it was confirmed that 2.28 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 4.21 mol% (5.24 wt%), and therefore the initiator-derived polyfunctional structure degree (e1 / c) was 0.97. In formula (1), R1 is phenyl, R2 is hydrogen, and R3 is sec-butyl. The amount of divinylbenzene-derived structural units having residual vinyl groups contained in the modified vinyl aromatic copolymer (G-1) was 0.13 mol % (0.16 wt %). The amount of modifier bonded to isoprene-derived units was 95.6 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (G-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.03.

[0145] Example 12 Synthesis of Modified Vinyl Aromatic Copolymer (H-1) 220 ml (171.4 g) of cyclohexane and 6.68 ml (46.0 mmol) of the co-catalyst triethylamine were charged, and 35.38 ml of an n-hexane solution containing 2.95 g (46.0 mmol) of pure sec-butyllithium (structural formula shown below) was added at 30°C. A solution of 3.10 g (23.0 mmol of divinylbenzene (a mixture of m- and p-isomers) and 0.77 mmol of ethylvinylbenzene (a mixture of m- and p-isomers) of DVB-960 (the structural formulas of divinylbenzene and ethylvinylbenzene are shown below), from which impurities had been removed in advance, dissolved in 90.7 ml (70.7 g) of cyclohexane was added over 2 hours. Stirring was continued at 30°C for 1 hour. Next, 19.2 g (0.184 mol) of styrene (structural formula below) and 12.5 g (0.184 mol) of isoprene (structural formula below) were added over 30 minutes to initiate the first stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 56°C. After completion of the polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was almost 100%. Next, 9.40 g (138 mmol) of isoprene (structural formula below) was added as an additional monomer to the reactor over 30 minutes, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small amount of the polymerization solution was sampled and analyzed by GC. No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 2500, an Mw of 3140, and an Mw / Mn of 1.26. Next, 11.47 g (46.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 10.86 g (92.0 mmol) of the neutralizing agent succinic acid was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the following structural formula. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 51.9 g (yield: 97.0 wt%) of modified vinyl aromatic copolymer H-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer H-1 are shown in Table 5.

[0146] The resulting modified vinyl aromatic copolymer H-1 had an Mn of 4030, an Mw of 9770, and an Mw / Mn ratio of 2.43. １３ C-NMR and １ By performing H-NMR analysis, the modified vinyl aromatic copolymer H-1 contained 3.99 mol% (5.59 wt%) of structural units derived from divinylbenzene, 0.13 mol% (0.19 wt%) of structural units derived from ethylvinylbenzene, 31.96 mol% (35.76 wt%) of structural units derived from styrene, 55.92 mol% (40.93 wt%) of structural units derived from isoprene, and 7.99 mol% (17.54 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and it was confirmed that 3.46 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 3.87 mol% (5.42 wt%), and therefore the initiator-derived polyfunctional structure degree (e1 / c) was 0.97. In formula (1), R1 is phenyl, R2 is hydrogen, and R3 is 2-methylbutyl. The amount of divinylbenzene-derived structural units with residual vinyl groups contained in the modified vinyl aromatic copolymer (H-1) was 0.12 mol % (0.17 wt %). The amount of modifier bonded to isoprene-derived units was 97.8 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (H-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.02.

[0147] Example 13 Synthesis of modified vinyl aromatic copolymer (I-1) 220 ml (171.4 g) of cyclohexane and 6.68 ml (46.0 mmol) of co-catalyst triethylamine were charged, and 35.38 ml of an n-hexane solution containing 2.95 g (46.0 mmol) of pure sec-butyllithium (structural formula shown below) was added at 30°C. A solution of 3.10 g (23.0 mmol of divinylbenzene (a mixture of m- and p-isomers) and 0.77 mmol of ethylvinylbenzene (a mixture of m- and p-isomers) of DVB-960 (the structural formulas of divinylbenzene and ethylvinylbenzene are shown below), from which impurities had been removed in advance, dissolved in 90.7 ml (70.7 g) of cyclohexane was added over 2 hours. Stirring was continued at 30°C for 1 hour. Next, 31.34 g (0.46 mol) of isoprene (structural formula below) was added over 60 minutes to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 42 ° C. After the polymerization reaction was completed, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. GPC analysis revealed that the copolymer at the time of polymerization completion had an Mn of 1680, an Mw of 2320, and an Mw / Mn of 1.38. Next, 11.47 g (46.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 10.86 g (92.0 mmol) of the neutralizing agent succinic acid was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the structural formula below. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 41.6 g (yield: 95.0 wt %) of modified vinyl aromatic copolymer I-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer I-1 are shown in Table 5.

[0148] The resulting modified vinyl aromatic copolymer I-1 had an Mn of 1850, an Mw of 3500, and an Mw / Mn ratio of 1.90. １３ C-NMR and １ By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer I-1 contained 4.34 mol% (6.83 wt%) of structural units derived from divinylbenzene, 0.15 mol% (0.23 wt%) of structural units derived from ethylvinylbenzene, 86.83 mol% (71.49 wt%) of structural units derived from isoprene, and 8.68 mol% (21.45 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and that 1.94 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 4.17 mol% (6.56 wt%), and the initiator-derived polyfunctional structure degree (e1 / c) was 0.96. In formula (1), R1 is phenyl, R2 is hydrogen, and R3 is 2-methylbutyl. The amount of divinylbenzene-derived structural units with residual vinyl groups contained in the modified vinyl aromatic copolymer (H-1) was 0.17 mol % (0.27 wt %). The amount of modifier bonded to isoprene-derived units was 98.2 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (H-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.04.

[0149] Example 14 Synthesis of modified vinyl aromatic copolymer (J-1) 220 ml (171.4 g) of cyclohexane and 6.68 ml (46.0 mmol) of co-catalyst triethylamine were charged, and 35.38 ml of an n-hexane solution containing 2.95 g (46.0 mmol) of pure sec-butyllithium (structural formula below) was added at 30°C. A solution of 2.44 g (23.0 mmol) of pre-dried m-xylene (the structural formula of m-xylene is shown below) dissolved in 40.0 ml (31.2 g) of cyclohexane was added over 15 minutes, and stirring was continued at 30°C for 1 hour. Next, 9.6 g (0.092 mol) of styrene (structural formula below) and 18.8 g (0.276 mol) of isoprene (structural formula below) were added over 30 minutes to initiate the first stage polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 58°C. After completion of the polymerization reaction, a small amount of the polymerization solution was sampled and analyzed by gas chromatography (GC). No unreacted monomer was observed, and it was confirmed that the polymerization conversion was nearly 100%. Next, 9.40 g (138 mmol) of isoprene (structural formula below) was added as an additional monomer to the reactor over 30 minutes, and the second-stage polymerization was initiated at 30°C. After the second-stage polymerization reaction was completed, a small amount of the polymerization solution was sampled and subjected to GC analysis. No unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was nearly 100%. GPC analysis revealed that the copolymer at the end of the second-stage polymerization had an Mn of 1540, an Mw of 2130, and an Mw / Mn of 1.38. Next, 11.47 g (46.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) was added as a modifier and the modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After the polymerization reaction was completed, 10.86 g (92.0 mmol) of the neutralizing agent succinic acid was added, stirred, and then filtered. Here, DEAMTES is a modifier having an alkoxysilyl group and an amino group at the same time, as shown in the following structural formula. The resulting polymerization solution was concentrated by devolatilization and then dissolved in ethylcyclohexane, but no gel or microgel was observed. As a result, 47.6 g (yield: 96.0 wt %) of modified vinyl aromatic copolymer J-1 was obtained in terms of solid content. The analytical results of modified vinyl aromatic copolymer J-1 are shown in Table 5.

[0150] The resulting modified vinyl aromatic copolymer J-1 had an Mn of 2,230, an Mw of 4,300, and an Mw / Mn ratio of 1.93. １３ C-NMR and １ By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer J-1 contained 4.00 mol% (4.92 wt%) of structural units derived from m-xylene, 16.00 mol% (19.31 wt%) of structural units derived from styrene, 72.00 mol% (56.83 wt%) of structural units derived from isoprene, and 8.00 mol% (18.94 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and that 2.07 modifiers were introduced per molecule of the modified vinyl aromatic copolymer. The polyfunctional structural unit (e1) represented by the formula (1) was 3.92 mol% (4.82 wt%), and the initiator-derived polyfunctional structure degree (e2 / d) was 0.98. In formula (1), R1 is phenyl, R4 is hydrogen, and R5 is hydrogen. The amount of m-xylene-derived structural units with residual methyl groups contained in the modified vinyl aromatic copolymer (J-1) was 0.08 mol % (0.10 wt %). The amount of modifier bonded to isoprene-derived units was 93.6 mol %. Thermogravimetry (TGA) showed that the weight loss at 350°C (TGA ３５０ A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (H-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere light transmittance measuring device with toluene as a reference sample. The haze value was 0.04.

[0151] The analytical results of the copolymers of Examples 10 to 14 are shown in Table 5.

[0152] Example 15 Synthesis of Modified Conjugated Diene Copolymer (F-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 68°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.487 g of the modified vinyl aromatic copolymer (F-1) obtained in Example 10 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) F-2 was obtained. The analytical results of the modified conjugated diene copolymer F-2 are shown in Table 6.

[0153] Example 16 Synthesis of Modified Conjugated Diene Copolymer (G-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 68°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.481 g of the modified vinyl aromatic copolymer (G-1) obtained in Example 11 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) G-2 was obtained. The analytical results of the modified conjugated diene copolymer G-2 are shown in Table 6.

[0154] Example 17 Synthesis of Modified Conjugated Diene Copolymer (H-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum of 68°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.466 g of the modified vinyl aromatic copolymer (H-1) obtained in Example 12 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) H-2 was obtained. The analytical results of the modified conjugated diene copolymer H-2 are shown in Table 6.

[0155] Example 18 Synthesis of Modified Conjugated Diene Copolymer (I-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 68°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.381 g of the modified vinyl aromatic copolymer (I-1) obtained in Example 13 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) I-2 was obtained. The analytical results of the modified conjugated diene copolymer I-2 are shown in Table 6.

[0156] Example 19 Synthesis of Modified Conjugated Diene Copolymer (J-2) A nitrogen-purged autoclave reactor was charged with 580 g of cyclohexane and 5 g of a cyclohexane solution containing 30.7 mg (0.16 mmol) of 2,2-di(2-tetrahydrofuryl)propane. At 50°C, 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of pure n-butyllithium was added, followed by the addition of 34.29 g of styrene and 80.00 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 68°C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.432 g of the modified vinyl aromatic copolymer (J-1) obtained in Example 14 was added as an SBR modifier to modify the resulting styrene-butadiene rubber (SBR), and a modification reaction was carried out. The modification reaction was carried out at a temperature of 60°C for 30 minutes to obtain a polymer solution. Further, 0.40 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant to the obtained polymerization solution, and the solvent was then removed by steam stripping. After vacuum drying, modified conjugated diene copolymer (modified SBR) J-2 was obtained. The analytical results of the modified conjugated diene copolymer J-2 are shown in Table 6.

[0157]

[0158] Example 20 The modified conjugated diene copolymer (modified SBR) F-2 obtained in Example 15, process oil, carbon black, zinc oxide, stearic acid, and antioxidant were blended according to the formulation shown in Table 3, and the blend was kneaded for 4 minutes at 155°C and 60 rpm using a Labo Plastomill. Sulfur and a vulcanization accelerator were added to the resulting blend, and the resulting blend was kneaded for 1 minute at 70°C and 60 rpm using a Labo Plastomill, followed by vulcanization to obtain crosslinked rubber F-3. The physical properties of the resulting crosslinked rubber are shown in Table 7.

[0159] Examples 21, 22, 23, and 24 Crosslinked rubbers G-3, H-3, I-3, and J-3 were obtained in the same manner as in Example 20, except that the modified conjugated diene copolymers (modified SBR) G-2, H-2, I-2, and J-2 synthesized in Examples 16, 17, 18, and 19 were used instead of the modified conjugated diene copolymer (modified SBR) F-2. The physical properties of the obtained crosslinked rubbers are shown in Table 7.

[0160]

[0161] According to Tables 4 and 7, the crosslinked rubber using the modified conjugated diene copolymer (modified SBR) of the Examples has a superior round rubber index compared to the Comparative Examples, which means that the dispersibility of the inorganic filler and loss during running are improved, and it is also superior in tensile strength and abrasion resistance, making it a material that can contribute to achieving both strength and abrasion resistance.

[0162] The modified vinyl aromatic copolymer of the present invention is particularly useful as a modifier for conjugated diene copolymers (e.g., SBR). Crosslinked rubbers obtained by incorporating a filler into the resulting modified conjugated diene copolymer (e.g., modified SBR) and crosslinking the copolymer exhibit excellent filler dispersibility, mechanical strength, and abrasion resistance, making them useful as elastomer materials for tires (treads), seismic isolation rubber, rubber hoses, rubber rollers, footwear materials, and the like. The modified vinyl aromatic copolymer of the present invention is also useful as a dielectric material, insulating material, heat-resistant material, structural material, adhesive, sealant, paint, coating agent, sealant, printing ink, dispersant, and the like in fields such as the electrical and electronics industries, the aerospace and aircraft industries, and the building and construction industries. The curable resin composition can be processed into films, sheets, and prepregs, and used in plastic optical components, touch panels, flat displays, film liquid crystal elements, and various optical elements such as optical waveguides and optical lenses. It can also be used as a modifier for modifying the heat resistance, dielectric properties, adhesiveness / adhesion, optical properties, and other properties of thermoplastic resins or curable resin compositions.

Claims

1. A polymer comprising structural units derived from one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b), The composition contains 0.5 mol % or more and 35.0 mol % or less of structural units derived from a polyfunctional vinyl aromatic compound (c) or an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms, and contains 65.0 mol % or more and 99.5 mol % or less of structural units derived from one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b); 50 mol % or more of the structural units derived from the component (c) or (d) are polyfunctional structural units (e1) represented by the following formula (1) having a group R1 derived from the aromatic structure of the component (c) or (d) and a group R2 or R3 derived from a structure other than the aromatic structure of the component (c) or (d), 【Chemistry 1】 Here, R1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R2 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer of 1 to 3. Polymer represents a main polymer structural unit derived from component (a) or component (b). The modified vinyl aromatic copolymer is further characterized in that the terminal of the polymer is modified with at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, the average number of functional groups per molecule is 2.0 or more, and the number average molecular weight Mn is 500 to 30,000.

2. The modified vinyl aromatic copolymer according to claim 1, characterized in that the polyfunctional structural unit (e1) represented by formula (1) is produced by reacting the component (c) or the component (d) with an organic alkali metal compound, and R3 is a group derived from the organic alkali metal compound.

3. (delete)

4. 2. The modified vinyl aromatic copolymer according to claim 1, wherein the molecular weight distribution (Mw / Mn), which is expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is 10.0 or less.

5. 2. The modified vinyl aromatic copolymer according to claim 1, wherein the average number of functional groups per molecule is in the range of 2 to 20.

6. The modified vinyl aromatic copolymer according to claim 1, wherein the monovinyl aromatic compound is at least one monomer selected from the group consisting of styrene, vinylnaphthalene, vinylbiphenyl, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, m-ethylvinylbenzene, indene and p-ethylvinylbenzene.

7. an initiation reaction step of reacting an alkali metal compound with one or more compounds selected from a polyfunctional vinyl aromatic compound (c) and an aromatic compound (d) having 2 to 4 alkyl groups having 1 to 3 carbon atoms to produce a polyfunctional anionic polymerization initiator; a polymerization step of polymerizing one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b) to obtain a vinyl aromatic copolymer having a polyfunctional structural unit (e1) represented by the formula (1) and an active terminal; and a terminal modification step of reacting an active terminal of the vinyl aromatic copolymer with a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, or a precursor compound thereof, to form a functional group.

8. A modified conjugated diene copolymer, which is a reaction product of a polymer of a conjugated diene compound constituting a diene rubber, or a copolymer of a conjugated diene compound and an aromatic vinyl compound, and the modified vinyl aromatic copolymer according to claim 1.

9. The modified conjugated diene copolymer according to claim 8, which contains 0.001 to 6% by weight of structural units (A1) derived from a modified vinyl aromatic copolymer, 29 to 99.999% by weight of structural units (B1) derived from a conjugated diene compound constituting a diene rubber, and 0 to 70% by weight of structural units (C1) derived from an aromatic vinyl compound constituting a diene rubber. Here, the conjugated diene compound of the structural unit (B1) is one or more selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene, and the aromatic vinyl compound of the structural unit (C1) is one or more selected from the group consisting of styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, vinylxylene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, tert-butoxydimethylsilylstyrene, and isopropoxydimethylsilylstyrene.

10. 2. The modified conjugated diene copolymer according to claim 1, wherein, in a differential molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement, the area of ​​a region having a number average molecular weight (Mn) three times or more of the lowest molecular weight peak is 20% or more when the total area is taken as 100%.

11. A resin composition comprising 0.5 to 200 parts by weight of at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides and carbon black, based on 100 parts by weight of the modified conjugated diene copolymer according to claim 8.

12. The resin composition according to claim 11, further comprising a crosslinking agent.

13. A crosslinked resin product obtained by crosslinking the resin composition according to claim 12.

14. A structural member comprising the cross-linked resin according to claim 13.

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