Modified vinyl aromatic copolymer and method for producing the same, modified conjugated diene copolymer obtained therefrom, resin composition, resin cross-linked product, and structural member

Abstract

To provide a modified vinyl aromatic copolymer that is useful as a modifier for conjugated diene-based copolymers (such as SBR), demonstrates excellent filler dispersibility, and services as a crosslinked rubber with superior mechanical strength and wear resistance.SOLUTION: 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), wherein the polymer contains structural units derived from multifunctional vinyl aromatic compounds (c) and the polymer has terminal ends modified by a modifier having at least one functional group selected from the group consisting of amino groups, alkoxysilyl groups, and hydroxyl groups. Additionally, the polymer has condensation structural units formed by condensation with a multifunctional condensate containing alkoxysilyl groups, and the polymer has an average functional group number per molecule of 3.0 to 30.0 and a number average molecular weight (Mn) of 500 to 30,000.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a modified vinyl aromatic copolymer, a method for producing the same, a modified conjugated diene copolymer having excellent processability, tensile strength and abrasion resistance, a resin composition obtained therefrom, a crosslinked resin obtained by crosslinking the same, and a structural member.

Background Art

[0002] A compound having a plurality of vinyl groups in the molecule easily undergoes an intermolecular crosslinking reaction by polymerization. By utilizing this property, such a compound is added to a polymerization system and copolymerized to form a crosslinked body, thereby insolubilizing the polymer or imparting functionality. For example, divinylbenzene can be mentioned as a compound having a plurality of vinyl groups in the molecule. By adding a small amount of this to a styrene polymerization system and copolymerizing it, and further introducing a functional group such as a sulfonic acid group, it can be used as an ion exchange resin. In addition, it is used as a crosslinking agent for styrene resins such as synthetic rubber, ABS resin, MBS resin, and unsaturated polyester resin, and as a modifier for polyethylene. As another example, it is also expected to impart functionality to a thermoplastic resin by reacting a polyfunctional vinyl aromatic copolymer having a branched structure with the thermoplastic resin. For example, conjugated diene rubbers such as SBR (styrene-butadiene rubber), BR (butadiene rubber), IR (isoprene rubber), and styrene-isoprene rubber are excellent in abrasion resistance, elasticity, and water resistance, and are used in various applications such as molding materials and resin modifiers.

[0003] One of the main uses of this conjugated diene rubber is tires for automobiles. The properties required for tires include mechanical strength, abrasion resistance, wet grip performance, etc. (hereinafter, also collectively referred to as strength, etc.). Furthermore, in recent years, the development of tires having excellent energy-saving performance, that is, low fuel consumption (so-called "eco-tires") has been actively carried out. These eco-tires are required to have low rolling resistance in addition to strength, etc.

[0004] In order to ensure the strength of a tire and the like, it is known to add fillers (reinforcing fillers) such as carbon black and silica to conjugated diene rubber. However, as a material for further improving the strength of a tire and the like and imparting excellent rolling resistance, end-modified solution-polymerized SBR (end-modified S-SBR) has attracted attention. End-modified S-SBR has a functional group at the molecular end of SBR, and this functional group at the molecular end interacts with the filler. Due to this interaction, the dispersibility of the filler in SBR is improved, and the molecular end of SBR is constrained and its mobility is reduced. As a result, the hysteresis loss (internal friction) of the tire is reduced and the rolling resistance is reduced. Taking advantage of this property, the development of eco-tires having both strength and low rolling resistance has been carried out.

[0005] In such a rubber composition, for the purpose of improving the affinity between the polymer used as the raw material rubber and the filler, various methods of introducing and modifying a predetermined functional group into a butadiene-based polymer which is the raw material rubber, for example, have been studied. For example, Patent Document 1 discloses synthesizing a block copolymer composed of an α-methylstyrene block and a butadiene block by living anionic polymerization using an organic lithium compound as an initiator in a nonpolar solvent, and further reacting a polyfunctional coupling agent if necessary. Patent Document 2 discloses a star-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 polyfunctional lithium-based initiator. The techniques of Patent Documents 1 and 2 are considered to have the effect of ensuring the processability of rubber by introducing a branched structure into the rubber component. However, there is no particular contrivance regarding the interaction with the filler for ensuring strength, and the contribution to strength is not sufficient. In Patent Document 3, a rubber composition is disclosed in which a predetermined amount of carbon black is compounded in a blend rubber containing a plurality of diene rubbers, and a low-molecular-weight functional group-containing polymer having a functional group that interacts with carbon black at the molecular chain end and having a polymer structure similar to the rubber component of the diene rubber is compounded. However, since this technique involves compounding a low-molecular-weight compound with rubber, its contribution to strength is not sufficient. Patent Document 4 discloses a rubber composition containing crosslinked rubber particles containing a conjugated diene unit, an aromatic vinyl unit, and a unit having at least two polymerizable unsaturated groups, and a conjugated diene / aromatic vinyl copolymer containing a conjugated diene unit having a specific bonding structure. However, at least one kind of functional group among the carboxylic acid group, amino group, hydroxyl group, epoxy group, and alkoxysilyl group introduced into the three-dimensionally crosslinked crosslinked rubber particles cannot enter the insoluble network structure inside the crosslinked rubber particles and contribute to the dispersibility of the inorganic filler outside the crosslinked rubber particles, and the effect of introducing the functional group was not sufficient. Patent Document 5 discloses a conjugated diene rubber composed of an interpenetrating network structure polymer composed of a crosslinked polymer having a structural unit derived from an ethylenically unsaturated compound whose glass transition temperature of the homopolymer is 10°C or higher and a structural unit derived from a crosslinkable compound, and a non-crosslinked polymer having a structural unit derived from a conjugated diene compound. However, since the crosslinked polymer is a polymer insoluble in a three-dimensionally crosslinked solvent, even as an interpenetrating network structure polymer with a non-crosslinked polymer having a structural unit derived from a conjugated diene compound, it has a structurally brittle microgel, so the effect of improving mechanical strength was not sufficient. Patent Document 6 discloses crosslinked polymer particles having polysiloxane on the particle surface and having an average particle diameter in the range of 0.01 to 10 μm. However, since the polysiloxane-modified crosslinked polymer particles are solvent-insoluble crosslinked polymer particles and are crosslinked polymer particles with hard and brittle characteristics, they cannot improve the strength when used for modifying a conjugated diene-based copolymer synthesized by anionic polymerization. Patent Document 7 discloses that a divinylidene polymerization initiator is reacted with a monomer to form an “omega, omega’-carbanion” living polymer molecule, and a modified polymer molecule is obtained by reacting at least one living polymer molecule with at least one equivalent of a chain-end modifier. However, when divinylbenzene is added as a coupling agent by post-addition, there is a problem that microscopic gels are generated and the effect of improving strength is not sufficient. Patent Document 8 discloses that a polymer obtained by crosslinking aminomethylated polystyrene with 1% divinylbenzene is swollen with methylene chloride and then reacted with tolylene 2,4-diisocyanate (TDI) to obtain a crosslinked polymer containing a silylated ferrocenyldiphosphine ligand. However, it is suggested that the crosslinked polymer has no solvent solubility, and a solvent-soluble branched polymer could not be envisioned. Patent Document 9 discloses a modified resin composition obtained by blending and kneading 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, which is obtained by performing anionic polymerization in the coexistence of an ethylene-styrene-divinylbenzene copolymer obtained by coordination polymerization and a styrene monomer. However, the cross-copolymer has a divinylbenzene content much lower than 0.5 mol%, and furthermore, there is no teaching as to whether the post-added silane coupling agent modifies the ends of the cross-copolymer, and there has been no suggestion that the characteristics of the conjugated diene-based polymer can be improved by coupling a conjugated diene-based living polymer.

[0006] Therefore, 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 an interaction function with a filler as a constituent unit of a conjugated diene rubber (Patent Document 10). Furthermore, in Patent Documents 11 to 14, polyfunctional vinyl aromatic copolymers having an indane structural unit, a structural unit derived from a cycloolefin compound, or a structural unit derived from styrene as essential components are proposed. The present invention contributes to the modification of resins by a method different from the methods disclosed in Patent Documents 10 to 14, and is particularly useful for rubber compositions such as tires, and proposes a material that can contribute to the improvement of properties such as strength and wear resistance.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Patent Document 11

Patent Document 12

Patent Document 13

Patent Document 14

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention solves such problems, and is particularly useful as a modifier for conjugated diene copolymers (such as SBR), and provides a modified vinyl aromatic copolymer which is a crosslinked rubber that is excellent in the dispersibility of fillers and excellent in mechanical strength and abrasion resistance.

Means for Solving the Problems

[0009] As a result of intensive studies, the present inventors have found that a polymer composed 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), contains a structural unit derived from a polyfunctional vinyl aromatic compound (c) in the polymer, and further, the terminal of the polymer is modified with a modifier having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, and the polymer has a predetermined condensed structural unit (f) condensed by a polyfunctional condensing agent containing an alkoxysilyl group. The present inventors have found that the above problems can be solved by the modified vinyl aromatic copolymer, and have completed the present invention.

[0010] The present invention is a polymer composed 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), contains a structural unit derived from a polyfunctional vinyl aromatic compound (c) in the polymer, further, the terminal of the polymer is modified with a modifier having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, in addition, the polymer has a condensed structural unit (f1) or (f2) represented by the following formula (f1) or (f2) condensed by a polyfunctional condensing agent containing an alkoxysilyl group, and the modified vinyl aromatic copolymer is characterized in that the average number of functional groups per molecule of the polymer is 3.0 to 30.0, and the number average molecular weight Mn is 500 to 30,000.

Chemical formula

[0011] Furthermore, in the present invention, 5 mol% or more of the structural unit derived from component (c) is generated by the reaction of component (c) with an organic alkali metal compound as a polymerization initiator, and is a polyfunctional structural unit (e1) represented by any one of the following formulas (1) to (3) having a group R1 derived from the aromatic structure of component (c), a group R2 derived from other than the aromatic structure of component (c), and a group R3 derived from the organic alkali metal compound. It is desirable that the modified vinyl aromatic copolymer be such.

Chemical formula

[0012] It is desirable that the polymer be obtained by causing a polyfunctional vinyl aromatic compound (c) and an organic alkali metal compound to undergo a polymerization initiation reaction in a molar ratio range of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound of 0.5 to 0.9.

[0013] Furthermore, the present invention includes an initiation reaction step of generating a polyfunctional anionic polymerization initiator by reacting an organic alkali metal compound as a polymerization initiator with a polyfunctional vinyl aromatic compound (c) in a molar ratio range of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound of 0.5 to 0.9, and One or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b) are polymerized to obtain a vinyl aromatic copolymer having a polyfunctional structural unit (e1) represented by any of the formulas (1) to (3) and an active terminal, and a polymerization step, Terminal modification is carried out by reacting 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, with the active terminal of the vinyl aromatic copolymer to form a functional group. At the same time, part or all of the polymer is polycondensed with a polyfunctional condensing agent containing at least one alkoxysilyl group to form a condensed structural unit (f1) or (f2) represented by the formula (f1) or (f2). A terminal modification and polycondensation step, which is a method for producing the modified vinyl aromatic copolymer, characterized by including

[0014] In the production method of the modified vinyl aromatic copolymer, in the polymerization step, after reacting a polyfunctional vinyl aromatic compound (c) with an organic alkali metal compound, a polyfunctional carbanion having a plurality of generated active sites is used as an essential functional group with one or more alkoxysilyl groups. It is desirable to condense with a polyfunctional condensing agent having a plurality of reactive functional groups selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group.

[0015] Furthermore, the present invention is a modified conjugated diene copolymer characterized by being obtained by reacting the above-mentioned modified vinyl aromatic copolymer with a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound.

[0016] In addition, the present invention is a resin composition, a resin crosslinked product, and a structural member containing the above-mentioned modified conjugated diene copolymer as an essential component.

Effects of the Invention

[0017] The modified vinyl aromatic copolymer of the present invention is useful as a raw material (modifying agent) for a modified conjugated diene copolymer. Further, a crosslinked resin composition obtained by containing a filler in the modified conjugated diene copolymer and crosslinking it is excellent in dispersibility of the filler and excellent in mechanical strength and abrasion resistance. Therefore, it is useful as an elastomer material such as a tire (especially a tire tread), a rubber for seismic isolation, a rubber hose, a rubber roller, and a footwear material.

Brief Description of the Drawings

[0018]

Figure 1

Embodiments for Carrying Out the Invention

[0019] The modified vinyl aromatic copolymer of the present invention (hereinafter also referred to as a modified copolymer or a copolymer) is a polymer composed 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), contains a structural unit derived from a polyfunctional vinyl aromatic compound (c) in the polymer, furthermore, the terminal of the polymer is modified with a modifying agent having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, in addition, the polymer has a condensed structural unit (f1) or (f2) represented by the following formula (f1) or (f2) condensed by a polyfunctional condensing agent containing an alkoxysilyl group, The modified vinyl aromatic copolymer is characterized in that the average number of functional groups per molecule of the copolymer is 3.0 to 20.0, and the number average molecular weight Mn is 500 to 30,000.

Chemical formula

[0020] The modified vinyl aromatic copolymer of the present invention (hereinafter also referred to as the modified copolymer or copolymer) is a polymer composed of structural units derived from one or more monomers selected from the group consisting of monovinyl aromatic compounds (a) and conjugated diene compounds (b), and contains structural units derived from a polyfunctional vinyl aromatic compound (c) in the polymer. 5 mol% or more of the structural units derived from the polyfunctional vinyl aromatic compound (c) are generated by the reaction of the component (c) with an organic alkali metal compound as a polymerization initiator, and have a group R1 derived from the aromatic structure of the component (c), a group R2 derived from other than the aromatic structure of the component (c), and a group R3 derived from the organic alkali metal compound, and are a polyfunctional structural unit (e1) represented by any one of the following formulas (1) to (3). [Chemical formula] Here, R2 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R4 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer of 1 to 3. Note that Polymer represents the main polymer structural unit derived from the component (a) or (b). The polymer is obtained by causing a polymerization initiation reaction between a polyfunctional vinyl aromatic compound (c) and an organic alkali metal compound in a molar ratio of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound in the range of 0.5 to 0.9. In the modified vinyl aromatic copolymer of the present invention, the degree of branching of the polymer can be increased by carrying out the polymerization initiation reaction in the range of 0.5 to 0.9 in the molar ratio of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound. The molar ratio of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound is preferably in the range of 0.55 to 0.8, more preferably in the range of 0.6 to 0.7.

[0021] The modified vinyl aromatic copolymer of the present invention can increase the amount of functional groups introduced per polymer molecule by condensing a vinyl aromatic copolymer having a plurality of carbanions obtained after reacting a polyfunctional vinyl aromatic compound (c) with an organic alkali metal compound, with a polyfunctional condensing agent having a plurality of reactive functional groups selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group, with the alkoxysilyl group being an essential functional group. The modified vinyl aromatic copolymer of the present invention has an average number of functional groups per molecule of 3.0 to 30.0. The average number of functional groups is preferably 5.0 to 20.0, more preferably 5.0 to 15.0. The modified vinyl aromatic copolymer of the present invention has an average degree of branching per molecule in the range of 2 to 30. The average degree of branching is preferably 2 to 20, more preferably 2 to 15.

[0022] In the modified vinyl aromatic copolymer of the present invention, 5 mol% or more of the structural units derived from the component (c) are polyfunctional structural units (e1) represented by the above formula (1) generated by the reaction of the component (c) with an organic alkali metal compound, and this polyfunctional structural unit (e1) plays an important role as a crosslinking component that branches the copolymer and makes it polyfunctional. Since the modified vinyl aromatic copolymer of the present invention has a high degree of branching of the polymer, when modifying polymers of conjugated diene compounds, high molecular weight multi-branched components are generated, and wear resistance can be improved.

[0023] Examples of the polyfunctional vinyl aromatic compound (c) preferably include diisopropenylbenzene, divinylbenzene, diisopropenylnaphthalene, divinylnaphthalene, diisopropenylbiphenyl, and divinylbiphenyl, but are not limited thereto. The exemplified compounds may each be an isomer such as an m-form or a p-form, or a mixture of these isomers. From the viewpoint of moldability, more preferably diisopropenylbenzene (m-form, p-form or a mixture of these isomers), divinylbenzene (m-form, p-form or a mixture of these isomers).

[0024] On the one 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 the monovinyl aromatic compound include 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, but are not limited thereto. In order to prevent the gelation of the copolymer and improve the solubility in a solvent, compatibility, and processability, styrene, ethylvinylbenzene, ethylvinylbiphenyl, ethylvinylnaphthalene, and indene are particularly preferably used from the viewpoints of cost and availability. The exemplified compounds may each be an isomer such as an m-form or a p-form, or a mixture of these isomers. From the viewpoints of compatibility and cost, styrene, ethylvinylbenzene (m-form, p-form, or a mixture of these isomers), and p-methylstyrene are more preferable.

[0025] 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 a function of enhancing the reactivity of the terminal modifying group of the modified vinyl aromatic copolymer when reacting the modified vinyl aromatic copolymer with a polymer of a conjugated diene compound having an active terminal or a copolymer of a conjugated diene compound having an active terminal and an aromatic vinyl compound.

[0026] As the conjugated diene compound, a conjugated diene compound containing 4 to 12 carbon atoms per molecule is preferred, and more preferably a conjugated diene compound containing 4 to 8 carbon atoms. Such conjugated diene compounds include, but are not limited to, for example, 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, from the viewpoints of the ease of copolymerization reaction with aromatic vinyl compounds and the ease of industrial availability, 1,3-butadiene and isoprene are preferred. These may be used alone or in combination of two or more.

[0027] The modified vinyl aromatic copolymer of the present invention is modified and condensed with a 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) and a polyfunctional condensing agent, and the introduction amounts of the modifier and the polyfunctional condensing agent per molecule correspond 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 3 to 30. When the number average molecular weight of the copolymer is divided by the functional group equivalent, if the value is 3.0 or more, it can be judged that 3 or more functional groups are introduced. The introduction amount of the functional group by a polymerization initiator or modifier having a functional group preferably has an average number of functional groups per molecule of 5 to 20, more preferably 5.0 to 15, and still more preferably 8.0 to 12.

[0028] The modified vinyl aromatic copolymer of the present invention can be produced, for example, by the following method. That is, it can be produced by a method including an initiation reaction step of generating a polyfunctional anionic polymerization initiator by reacting an organic alkali metal compound with a polyfunctional vinyl aromatic compound (c), 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 any one of the formulas (1) to (3) and an active terminal, and a terminal modification step of reacting 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, with the active terminal of the vinyl aromatic copolymer to form a functional group.

[0029] The modified vinyl aromatic copolymer of the present invention is a copolymer containing a structural unit (a) derived from a monovinyl aromatic compound, a structural unit (b) derived from a conjugated diene compound, and a polyfunctional vinyl aromatic compound (c). However, within a range not impairing the effects of the structural units derived from the components (a) to (c), a compound other than a conjugated diene compound and an aromatic vinyl compound (hereinafter, also referred to as "other monomer") can be used, and a structural unit derived from these other monomers (f) can be introduced into the copolymer.

[0030] Specific examples of the above other monomer (f) preferably include acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, etc., but are not limited thereto. These can be used alone or in combination of two or more. The other monomer (f) is preferably used within a range of less than 30 mol% of all the monomers. Thereby, the structural unit derived from the other monomer (f) is introduced within a range of less than 30 mol% with respect to the total amount of the structural units in the copolymer. It is preferably 10 mol% or less, and more preferably 5 mol% or less.

[0031] In the method for producing a modified vinyl aromatic copolymer of the present invention, in the initiation reaction step, an organic alkali metal compound and a polyfunctional vinyl aromatic compound (c) are reacted to produce a polyfunctional anionic polymerization initiator (carbanion) as an intermediate product.

[0032] The structural unit of the polyfunctional anionic polymerization initiator produced in the above initiation reaction step becomes a polyfunctional structural unit (e1) represented by any one of the following formulas (1) to (3) through the polymerization step.

Chemical formula

[0033] The present invention relates to a polyfunctional structural unit (e1) represented by any one of formulas (1) to (3) generated based on the reaction of a polyfunctional vinyl aromatic compound (c) and an organic alkali metal compound as a polymerization initiator. In formula (e1), R3 is a hydrogen atom at the α-position of the vinyl group of component (c) or a hydrocarbon group having 1 to 6 carbon atoms. For example, when butyl Li (C4H9Li) is used as the organic alkali metal compound of the initiator, as shown in the following reaction formula, an active species (carbanion) is generated by the reaction of butyl Li and component (c). Therefore, the pentyl group formed by adding the carbon atom at the β-position of the vinyl group and the butyl group derived from butyl Li represents R4. [Chemical formula]

[0034] Among the structural units derived from component (c), the proportion (polyfunctionality degree) of the polyfunctional structural unit (e1) represented by any one of formulas (1) to (3) is a parameter that can be arbitrarily controlled and changed, but it is essential that this ratio is 5 mol% or more. In the case where it is less than 5 mol%, when the number average degree of polymerization of the polymer of the polyfunctional vinyl aromatic compound, which is the reaction product of the polyfunctional vinyl aromatic compound (c) per molecule and the organic alkali metal compound as a polymerization initiator, exceeds 100, the solubility of the growing polymer chain decreases, and it is easy to generate a solvent-insoluble gel-like substance, and the introduction efficiency of the functional group decreases. Therefore, when this polymer is used for the modification of the conjugated diene-based (co)polymer, the branching reaction of the conjugated diene-based (co)polymer does not proceed sufficiently, so that the molecular weight does not increase sufficiently, or the presence of the gel-like substance tends to reduce the improvement effect on strength and abrasion resistance. 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 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, and most preferably 5 mol% or less. Here, by suppressing the residual vinyl content within the range of 30 mol% or less, the amount of the modifier introduced can be increased. Therefore, when this polymer is used for the modification of the conjugated diene-based (co)polymer, the molecular weight increases and the number of functional groups is increased, which is preferable for achieving both good filler dispersibility and wear resistance.

[0035] In the method for producing the modified vinyl aromatic copolymer of the present invention, the organic alkali metal compound used in the initiation reaction step is not particularly limited, but for example, an organic lithium compound is preferable. Specific examples thereof include alkyl lithiums such as methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, and t-butyl lithium, and phenyl lithium, stilbene lithium, naphthyl lithium, and the like. The amount of the organic alkali metal compound used is desirably such that the molar ratio of the polyfunctional vinyl aromatic compound (c) / organic alkali metal compound is in the range of 0.2 to 1.0. The molar ratio of the polyfunctional vinyl aromatic compound (c) / organic alkali metal compound is preferably in the range of 0.4 to 0.9, more preferably in the range of 0.5 to 0.7. When the molar ratio of the polyfunctional vinyl aromatic compound (c) / organic alkali metal compound exceeds 1.0, when this polymer is used for the modification of the conjugated diene-based (co)polymer, there is a tendency for gel content to be generated, and thus the improvement effect on strength and wear resistance tends to be reduced. On the other hand, when the molar ratio of the polyfunctional vinyl aromatic compound (c) / organic alkali metal compound is less than 0.5, the branching reaction does not proceed sufficiently, so the molecular weight does not increase sufficiently, and the improvement effect on strength and wear resistance tends to be reduced. The amount of the polyfunctional anionic polymerization initiator (carbanion) obtained by reacting an organic alkali metal compound as a polymerization initiator with a polyfunctional vinyl aromatic compound (c) is preferably 3.0 to 300 mmol with respect to 1.0 mol of the monomer used for the polymerization.

[0036] When butyllithium (C4H9Li) is used as the organic alkali metal compound of the polymerization initiator, as shown in the following reaction formula, an active species (carbanion) is generated by the reaction of butyllithium with the (c) component. Here, the Li site becomes a carbanion and an active site. From the left, a monomer, a dimer, and a trimer are shown.

Chemical formula

[0037] In the initiation reaction step, it may be carried out using a mixture of an organic alkali metal compound and a compound having a functional group that interacts with silica. By carrying out the initiation reaction in the presence of the 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 "functional group that interacts with silica" means a group having an element that interacts with silica such as nitrogen, sulfur, phosphorus, or oxygen. "Interaction" means forming a covalent bond between molecules or forming an intermolecular force weaker than a covalent bond (for example, electromagnetic forces acting between molecules such as ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). As the compound having a functional group that interacts with silica and is used for the denaturation of the coincidence start end, among others, nitrogen-containing compounds such as secondary amine compounds are preferable. Specific examples of the nitrogen-containing compound include, for example, 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, 1,3-ditrimethylsilyl-1,3,5-triazinane, and the like.

[0038] In the above initiation reaction step, a polar compound may be added. By adding a polar compound, it is involved in the initiation reaction and the growth reaction, and is also effective in controlling the molecular weight and molecular weight distribution and promoting the polymerization reaction. Examples of the polar compound 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, 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, quinuclidine; alkali metal alkoxide compounds such as potassium-tert-amylate, potassium-tert-butyrate, sodium-tert-butyrate, sodium amylate; phosphine compounds such as triphenylphosphine, and the like. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound used is not particularly limited and can be selected according to the purpose and the like. Usually, it is preferably 0.01 to 100 moles per 1 mole of the organic alkali metal compound.

[0039] 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 for example, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons are used. Specifically, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, and decalin; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbon solvents composed of mixtures thereof can be mentioned. It is preferable to treat the above-mentioned monomer and polymerization solvent, either alone or as a mixture thereof, with an organometallic compound. Thereby, it is possible to treat the divinyl aromatic compound, monomers such as monovinyl aromatic compounds, and allenes and acetylenes contained in the polymerization solvent. As a result, a polymer having a high-concentration active terminal can be obtained, and a high modification rate can be achieved.

[0040] The polymerization temperature during copolymerization is not particularly limited as long as living anion polymerization proceeds, but from the viewpoint of productivity, it is preferably -20°C to 150°C. From the viewpoint of ensuring a sufficient reaction amount to the active terminal in the terminal modification step after the polymerization is completed, it is preferably -20°C to 120°C. More preferably, it is 0°C to 100°C.

[0041] The mode of the above polymerization reaction is not particularly limited, but it can be carried out by a polymerization mode such as a batch process (also referred to as a "batch process") or a continuous process. In the continuous process, one or two or more connected reactors can be used. As the reactor, a tank type with a stirrer, a tubular type, etc. are used. In the batch process, the molecular weight distribution of the obtained polymer is generally narrow, and it is likely to be 1.0 or more and less than 3.0 in terms of Mw / Mn. Also, in the continuous process, the molecular weight distribution is generally wide, and it is likely to be 1.5 or more and 10 or less in terms of Mw / Mn.

[0042] In the production method of the present invention, after obtaining a polyfunctional structural unit (e1) represented by any one of formulas (1) to (3) and a vinyl aromatic copolymer having an active end, which are generated by the reaction of component (c) and an organic alkali metal compound in the polymerization step, at this active end, a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group (including a precursor, and these are also referred to as a modifier) is reacted to introduce a functional group to the end of the modified vinyl aromatic copolymer of the present invention. The modifier reacts with the active end of the copolymer and, in the present invention, binds to the active end derived from the conjugated diene compound (b). It is preferable that the modifier binding to the active end 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 the abrasion resistance when used as an automobile tire. Preferably it is 70 mol% or more, more preferably 80 mol% or more, still more preferably 85 mol% or more, and particularly preferably 90 mol% or more.

[0043] Regarding the reaction temperature, reaction time, etc. when reacting a compound (including a precursor) having a functional group at the active end, there is no particular limitation, but it is preferable to react at -20°C to 120°C for 30 seconds or more. The addition amount of the modifier having a functional group is not particularly limited, but in the initiation reaction step, with respect to the number of equivalents of the active species induced by the polyfunctional anionic polymerization initiator obtained by reacting an organic alkali metal compound and a polyfunctional vinyl aromatic compound (c), it is preferable that the total number of moles of the modifier having a functional group is in the range of 0.3 to 6 times. A more preferable lower limit is 0.4, still more preferably 0.5, and particularly preferably 0.6. On the other hand, a more preferable upper limit is 3 times, still more preferably 2 times, and particularly preferably 1.5 times. If the addition amount is 0.3 times or more, it is preferable from the viewpoint of obtaining a sufficient modification rate in the target modified vinyl aromatic copolymer.

[0044] In the terminal modification step, when the polymerization step is a batch process, the modification reaction may be carried out continuously in the reactor used in the polymerization step or may be carried out after transferring to the next reactor. When the polymerization step is a continuous process, it is carried out after transferring to the next reactor. The terminal modification step is preferably carried out immediately following the polymerization step, and preferably, a modifier is mixed within 5 minutes to initiate the reaction. The reactor for the modification reaction is preferably one in which sufficient stirring is carried out. Specifically, there are static mixer type reactors, tank type reactors equipped with stirrers, etc.

[0045] The terminal modification step is a step of modifying the active terminal of the vinyl aromatic copolymer by reacting it with a modifier having at least one functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group. The modifier must have an amino group, an alkoxysilyl group, or a hydroxyl group as a functional group, and may have other functional groups, such as a halogen group, a ketone group, an ester group, an amide group, and an epoxy group, as long as the object of the present invention is not inhibited.

[0046] The modifier having an amino group is not particularly limited, but specifically, compounds having an amino group and a functional group that binds to the polymer active terminal in the molecule, preferably compounds having no active hydrogen, can be mentioned. The amino group is not particularly limited, but specifically, a functional group that is inert to an alkali metal is preferable, and a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, and an amino group in which two hydrogens are protected are preferable. Examples of the protected monosubstituted amino group or the amino group in which two hydrogens are protected include those in which one hydrogen of the monosubstituted amino group or two hydrogens of the amino group are each substituted with a trialkylsilyl group.

[0047] The modifier having an alkoxysilyl group is not particularly limited, but specifically, compounds having a plurality of alkoxysilyl groups in the molecule (including compounds having a silyl group to which a plurality of alkoxy groups are bonded), and compounds having an alkoxysilyl group and a functional group that binds to the polymer active terminal in the molecule can be mentioned. These are preferably compounds having no active hydrogen.

[0048] The modifier that forms a hydroxyl group is not particularly limited. Specifically, it includes a compound having a functional group that binds to the polymer active end and generates a hydroxyl group after the binding reaction, and a compound having a functional group that does not bind to the polymer active end and generates a hydroxyl group by a reaction such as hydrolysis later. It is preferably a compound having no active hydrogen. Examples of the compound having a functional group that generates a hydroxyl group after the binding reaction include compounds having a ketone group, an ester group, an amide group, an epoxy group, etc. Examples of the compound having a functional group that generates a hydroxyl group by a reaction such as hydrolysis after the binding reaction include compounds having an alkoxysilyl group, an aminosilyl group, etc.

[0049] Specific examples of the modifier are shown below. The compound that binds to the polymer active end and forms an amino group at the end of the polymer is not particularly limited, and examples thereof include C=N double bond compounds such as N,N'-dicyclohexylcarbodiimide. The compound that binds to the polymer active end and forms an amino group and a hydroxyl group at the end of the polymer is not particularly limited, and examples thereof include ketone compounds having an amino group such as N,N,N',N'-tetramethyl-4,4'-diaminobenzophenone (Michler's ketone), N,N,N',N'-tetraethyl-4,4'-diaminobenzophenone; cyclic urea compounds such as N,N'-dimethylimidazolidinone, N-methylpyrrolidone; cyclic amides, that is, lactam compounds; amino group-containing epoxy compounds such as N,N,N',N'-tetraglycidyl-1,3-bis(aminomethyl)cyclohexane; epoxy compounds having a nitrogen-containing heterocyclic group described in JP-A-2001-131227, etc. The compounds that bind to the polymer active terminal to form an alkoxysilyl group at the end of the polymer are not particularly limited, and examples thereof include alkylalkoxysilane compounds such as n-decyltrimethoxysilane, n-decyltriethoxysilane, n-hexadecyltrimethoxysilane, n-hexadecyltriethoxysilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, i-octyltrimethoxysilane, i-octyltriethoxysilane, i-butyltrimethoxysilane, i-butyltriethoxysilane, propyltrimethoxysilane, and propyltriethoxysilane.

[0050] The compounds that bind to the polymer active terminal to form an amino group and an alkoxysilyl group at the terminal of the polymer are not particularly limited, but include alkoxysilane compounds having an alkyl group with an amino substituent such as diethylaminomethyltrimethoxysilane, diethylaminomethyltriethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropyldiethoxymethylsilane, 3-diethylaminopropyltrimethoxysilane, 3-diethylaminopropyldimethoxymethylsilane, 3-diethylaminopropyltriethoxysilane, 3-diethylaminopropyldiethoxymethylsilane, bis(3-trimethoxysilylpropyl)methylamine, bis(3-triethoxysilylpropyl)methylamine; alkoxysilane compounds having a protected monosubstituted amino group bonded thereto as described in WO2007 / 034785 such as N-[3-(triethoxysilyl)-propyl]-N,N'-diethyl-N'-trimethylsilyl-ethane-1,2-diamine, 3-(4-trimethylsilyl-1-piperazinyl)propyltriethoxysilane; alkoxysilane compounds having a plurality of substituted amino groups bonded thereto as described in WO2008 / 013090 such as N-[2-(trimethoxysilyl)-ethyl]-N,N',N'-trimethylethane-1,2-diamine, 1-[3-(triethoxysilyl)-propyl]-4-methylpiperazine, 2-(trimethoxysilyl)-1,3-dimethylimidazolidine, bis-(3-dimethylaminopropyl)-dimethoxysilane; alkoxysilane compounds having a nitrogen-containing heterocycle bonded thereto as described in WO2011 / 040312 such as 1,4-bis[3-(trimethoxysilyl)propyl]piperazine, 1,4-bis[3-(triethoxysilyl)propyl]piperazine;Examples thereof include alkoxysilane compounds having an azasilane group bonded thereto, such as 3-[N,N-bis(trimethylsilyl)amino]propyltrimethoxysilane, 3-[N,N-bis(trimethylsilyl)amino]propylmethyldiethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, etc. described in WO2011 / 129425; The compound that binds to the polymer active end to form a hydroxyl group at the end of the polymer is not particularly limited, and examples thereof include epoxy compounds such as ethylene oxide and propylene oxide; ketone compounds such as benzophenone.

[0051] The method for producing the modified vinyl aromatic copolymer of the present invention is characterized in that after reacting a polyfunctional vinyl aromatic compound (c) with an organic alkali metal compound, the polyfunctional carbanion having a plurality of generated active sites is condensed in the polymerization step by a polyfunctional condensing agent having a plurality of reactive functional groups selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group, with the alkoxysilyl group as an essential functional group. By condensing the polyfunctional carbanion having a plurality of active sites with a polyfunctional condensing agent having a plurality of alkoxysilyl groups, it is possible to increase the degree of condensation of the modified vinyl aromatic copolymer of the present invention obtained and further increase the introduction amount of the alkoxysilyl group. The condensation with the polyfunctional condensing agent is preferably carried out in combination with the terminal modification with the modifier. The polyfunctional condensing agent used as an essential component when producing the modified vinyl aromatic copolymer of the present invention belongs to the modifiers described in the present invention, but the use ratio of the polyfunctional condensing agent and other modifiers can be used at any ratio. The addition amount of the polyfunctional condensing agent is preferably in the range of 0.1 to 0.95 mol, more preferably in the range of 0.15 to 0.90 mol, and even more preferably in the range of 0.25 to 0.80 mol, per 1 mol of the organic alkali metal compound, in order to increase the degree of condensation of the modified vinyl aromatic copolymer of the present invention obtained and increase the introduction amount of the alkoxysilyl group. The upper limit of the weight-average degree of condensation of the modified vinyl aromatic copolymer of the present invention obtained by using the polyfunctional condensing agent is preferably 100, more preferably 50, even more preferably 20, and particularly preferably 10. The lower limit of the weight-average degree of condensation is preferably 2, more preferably 3, and even more preferably 4.

[0052] As the polyfunctional condensing agent having a plurality of reactive functional groups selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group, with one or more alkoxysilyl groups as essential functional groups, for example, when bis(triethoxysilyl)ethane is used, the polyfunctional carbanion generated in the initiation reaction condenses as shown in the following reaction formula.

Chemical formula

[0053] Specific examples of the polyfunctional condensing agent that can be used in the present invention include polyfunctional condensing agents having two or more alkoxysilyl groups such as 1,2-bis(triethoxysilyl)ethane, 1,2-bis(trimethoxysilyl)ethane, 1,6-bis(triethoxysilyl)hexane, 1,6-bis(trimethoxysilyl)hexane, tris(3-(trimethoxysilyl)propyl)isocyanurate, tris(3-(triethoxysilyl)propyl)isocyanurate, etc.; polyfunctional condensing agents having an epoxy group and an alkoxysilyl group such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, 8-glycidoxyoctyltriethoxysilane, 8-glycidoxypropyloctyldiethoxysilane, etc.; polyfunctional condensing agents having a halogenated alkyl group and an alkoxysilyl group such as 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane, 3-chloropropylmethyldiethoxysilane, methylchlorotrimethoxysilane, methylchlorotriethoxysilane, etc.; polyfunctional condensing agents having a vinyl group and an alkoxysilyl group such as p-styryltrimethoxysilane, p-styrylmethyldimethoxysilane, p-styryltriethoxysilane, p-styrylmethyldiethoxysilane, etc. However, the invention is not limited thereto. Among the polyfunctional condensing agents described above, from the viewpoint that when a conjugated diene copolymer having an active terminal obtained by anionic living polymerization is reacted with the polyfunctional aromatic vinyl copolymer of the present invention to condense the conjugated diene copolymer, a multi-branched body can be efficiently generated, it is preferable to use a polyfunctional condensing agent having two or more alkoxysilyl groups. From the viewpoint of industrial implementation, 1,2-bis(triethoxysilyl)ethane and 1,2-bis(trimethoxysilyl)ethane are more preferable.

[0054] The modified vinyl aromatic copolymer of the present invention obtained by the above production method is modified with at least one functional group selected from the group consisting of a reactive amino group, an alkoxysilyl group, and a hydroxyl group. Therefore, it may be molded and cured alone, but it is preferable to use other polymerizable resins for functional group modification and synthesis of a high molecular weight multi-branched component. In particular, the modified vinyl aromatic copolymer of the present invention is used for functional group modification and synthesis of a high molecular weight multi-branched component when obtaining a conjugated diene compound alone and / or a conjugated diene-based copolymer (rubber) copolymerized with a conjugated diene compound and another monomer.

[0055] The modified copolymer of the present invention is excellent as a modifier for a conjugated diene-based (co)polymer (rubber). Although the detailed mechanism is unknown, an appropriate amount of functional groups are introduced into the modified copolymer of the present invention, so that the rubber is modified to become a modified conjugated diene-based copolymer (modified rubber), which is likely to concentrate near the reinforcing filler, and the reinforcing effect of the reinforcing filler becomes large, leading to an improvement in the abrasion resistance of the resulting crosslinked product. In addition, by means of the modified rubber, the affinity between the modified conjugated diene-based copolymer of the present invention and the reinforcing filler is improved, and the dispersion state of each component such as the reinforcing filler in the resin composition is ideally improved for the physical properties of the resulting crosslinked product (for example, improvement in abrasion resistance, improvement in handling stability, dry grip performance, wet grip performance). On the other hand, if the number of functional groups of the modified conjugated diene-based copolymer becomes too large, the reinforcing filler will aggregate due to the interaction between the copolymers adsorbed on the reinforcing filler, and it is presumed that this copolymer does not contribute to the improvement of the affinity between the modified conjugated diene-based copolymer and the reinforcing filler.

[0056] The average number of functional groups per molecule of the modified vinyl aromatic copolymer can be determined by the following formula (1) from the equivalent weight (g / eq) of the functional group of the modified vinyl aromatic copolymer (A) and the number average molecular weight Mn in terms of styrene. Average number of functional groups per molecule = (number average molecular weight Mn) / (equivalent weight of functional group) (1) Here, the number average molecular weight Mn in the formula (1) represents the average molecular weight of the modified vinyl aromatic copolymer composed of divinyl aromatic compound units, monovinyl aromatic compounds, conjugated diene compounds, and functional groups. In addition, the equivalent weight of the functional group of the modified vinyl aromatic copolymer (A) means the mass of the divinyl aromatic compound unit and the monovinyl aromatic compound bonded per one functional group. The equivalent weight of the functional group can be 1 calculated from the area ratio of the peak derived from the functional group and the peak derived from the polymer main chain using H-NMR or 13 C-NMR.

[0057] The average number of functional groups per molecule in the modified vinyl aromatic copolymer (A) is preferably 3.0 to 30. More preferably 5.0 to 20, and particularly preferably 5.0 to 15. When the average number of functional groups per molecule exceeds 30, the viscosity increases when the reinforcing filler (D) is dispersed, the processability deteriorates, and the abrasion resistance of the resulting crosslinked product also tends to decrease. When the average number of functional groups per molecule is lower than 3.0, the dispersibility effect of the reinforcing filler (D) is poor, and it is not ideal for improving the physical properties of the crosslinked product in which the dispersion state of the reinforcing filler (D) and the like can be obtained. The introduction amount of the 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.

[0058] The modified vinyl aromatic copolymer of the present invention contains 0.5 to 35.0 mol% of structural units derived from the polyfunctional vinyl aromatic compound (c). When the structural units consist only of the structural units derived from (a), (b), and (c), the structural units derived from the polyfunctional vinyl aromatic compound (c) are 0.005 to 0.35 with respect to the total of the structural units derived from (a), (b), and (c). This molar fraction is calculated by the following formula (2). [(c)] / [(a)+(b)+(c)] (2) (Here, (a) is the molar fraction of the structural unit derived from the monovinyl aromatic compound (a), (b) is the structural unit derived from the conjugated diene compound (b), and (c) is the molar fraction of the structural unit derived from the divinyl aromatic compound (c).) The lower limit of the above molar fraction is preferably 0.006, more preferably 0.007. The upper limit is preferably 0.35, more preferably 0.30. Most preferably, it is 0.01 to 0.25. In the case of containing structural units other than those derived from (a), (b), and (c), the lower limit of the preferred content is 0.2 mol%, more preferably 0.4 mol%, and still more preferably 0.6 mol%. The upper limit is preferably 35 mol%, more preferably 30 mol%, and still more preferably 25 mol%.

[0059] 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 the monovinyl aromatic compound (a) and the conjugated diene compound (b). In terms of molar fraction, it is 0.65 to 0.995. The lower limit is preferably 0.70. The lower limit is more preferably 0.75. The upper limit is preferably 0.994, more preferably 0.993. Most preferably, it is 0.75 to 0.99. The molar fraction of the structural units derived from one or more monomers selected from the group consisting of the monovinyl aromatic compound (a) and the conjugated diene compound (b) is calculated by the following formula (3) when it consists only of the structural units (a), (b), and (c). [(a)+(b)] / [(a)+(b)+(c)] (3) (Here, (a), (b), and (c) have the same meaning as in formula (3).) Even when containing structural units other than those derived from (a), (b), and (c), the preferred molar fraction of the structural units derived from (a) and (b) is within the above range.

[0060] In addition to the above structural units, the modified vinyl aromatic copolymer of the present invention can contain other structural units. The details of the other structural units can be understood from the description of the production method.

[0061] The Mn (number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography) of the modified vinyl aromatic copolymer of the present invention is from 500 to 30,000. A preferred lower limit is 600, more preferably 700, still more preferably 800, and particularly preferably 900. On the other hand, a preferred upper limit is 25,000, more preferably 20,000, still more preferably 15,000, and particularly preferably 10,000. When Mn is less than 500, the amount of functional groups contained in the copolymer decreases, so the reactivity with the active terminals of the conjugated diene copolymer tends to decrease. Also, when it exceeds 30,000, gels are likely to form, and the molding processability and tensile elongation at break 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. Particularly preferably, it is 3.0. When Mw / Mn exceeds 10.0, the processing characteristics of the copolymer rubber tend to deteriorate, and gels tend to occur.

[0062] The modified vinyl aromatic copolymer of the present invention is soluble in a solvent selected from toluene, xylene, tetrahydrofuran, dichloroethane or chloroform, and is preferably soluble in any of the above solvents. And it is preferably soluble in 50 g or more in 100 g of these solvents. More preferably, it is soluble in 80 g or more.

[0063] Since the modified vinyl aromatic copolymer of the present invention has at least one functional group selected from the group consisting of a reactive amino group, an alkoxysilyl group, and a hydroxyl group, it may be molded and cured alone, but it is preferable to use it for functional group modification and synthesis of a high molecular weight multi-branched component of another polymerizable resin. In particular, the modified vinyl aromatic copolymer of the present invention is used for functional group modification and synthesis of a high molecular weight multi-branched component when obtaining a conjugated diene compound alone and / or a conjugated diene copolymer (rubber) copolymerized with a conjugated diene compound and another monomer.

[0064] Using the polyfunctional vinyl aromatic copolymer (A) of the present invention as a raw material, by copolymerizing 1) a conjugated diene compound (B) or 2) a conjugated diene compound (B) and an aromatic vinyl compound (C), a modified conjugated diene-based copolymer having a branched polymer-type modifying group (A) based on the modified vinyl aromatic-based copolymer of the present invention can be obtained. When the aromatic vinyl compound (C) is not used, modified diene-based rubbers such as butadiene rubber and isoprene rubber can be obtained, and by using the aromatic vinyl compound (C), modified conjugated diene-based copolymers such as modified SBR can be obtained. Since these modified conjugated diene-based copolymers exhibit rubber properties, they are also referred to as modified copolymer rubbers.

[0065] The polymerization step for obtaining the modified conjugated diene-based copolymer of the present invention uses an alkali metal compound or an alkaline earth metal compound as a polymerization initiator to polymerize the conjugated diene compound (B) or copolymerize the conjugated diene compound (B) and the aromatic vinyl compound (C) to obtain a conjugated diene-based copolymer having an active terminal, and a terminal modification step for introducing the branched polymer-type modifying group (A) based on the modified vinyl aromatic-based copolymer.

[0066] 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, 1,3-hexadiene, etc. Among these, 1,3-butadiene and isoprene are preferred. These may be used alone or in combination of two or more.

[0067] Examples of the aromatic vinyl compound (C) include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, vinylxylene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, tert-butoxydimethylsilylstyrene, and isopropoxydimethylsilylstyrene, which can be used alone or in combination of two or more. Among these, styrene is particularly preferred. When 1,3-butadiene is used as the conjugated diene compound (B) and styrene is used as the aromatic vinyl compound (C), so-called styrene-butadiene rubber (SBR) is obtained. Also, 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), it becomes isoprene rubber (IR). Among them, having a styrene-butadiene rubber (SBR) structure is particularly preferable because it is excellent in abrasion resistance, heat resistance, and aging resistance.

[0068] In the method for producing the modified conjugated diene-based copolymer of the present invention, the polymerization step and the terminal modification step can be carried out in the same manner as the polymerization step and the terminal modification step of the modified vinyl aromatic copolymer described above. As the polymerization initiator used in the polymerization step and the compound having a functional group used in the terminal modification step, the above-described polymerization initiator and the compound having a functional group can also be used.

[0069] This polymerization, the 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 for example, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons are used. Specifically, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, and decalin; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbon solvents composed of mixtures thereof can be mentioned. It is preferable to treat the above-described conjugated diene-based compound and the polymerization solvent, either alone or as a mixture thereof, with an organometallic compound. Thereby, allenes and acetylenes contained in the conjugated diene compound and the polymerization solvent can be treated. As a result, a polymer having a high-concentration active terminal can be obtained, and a high modification rate can be achieved.

[0070] When copolymerizing the conjugated diene compound (B) or copolymerizing the conjugated diene compound (B) and the aromatic vinyl compound (C), the polymerization temperature 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, and from the viewpoint of sufficiently ensuring the reaction amount of the modified vinyl aromatic copolymer having the structural unit (c) composed of the silane-based functional group represented by the above formula (2) and / or formula (3) of the present invention with respect to the active terminal after the polymerization is completed, it is preferably 120 °C or lower. More preferably, it is 50 to 100 °C. The polymerization mode when copolymerizing the conjugated diene compound (B) or copolymerizing the conjugated diene compound (B) and the aromatic vinyl compound (C) is not particularly limited, but it can be carried out in a polymerization mode such as a batch method (also referred to as a "batch method") or a continuous method. In the continuous method, one or two or more connected reactors can be used. As the reactor, a tank type with a stirrer, a tubular type, etc. are used. In the batch method, the molecular weight distribution of the obtained polymer is generally narrow, and it is likely to be 1.0 or more and less than 1.8 in terms of Mw / Mn. In the continuous method, the molecular weight distribution is generally wide, and it is likely to be 1.8 or more and 3 or less in terms of Mw / Mn.

[0071] The weight average molecular weight (polystyrene conversion) 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 in consideration of processability and physical properties. The weight average molecular weight can be determined by measuring a chromatogram using GPC with a column filled with a polystyrene-based gel as a filler and using a calibration curve using standard polystyrene. In the differential molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement, when the total area is taken as 100%, it is preferable that the area of the region having a number average molecular weight (Mn) of 3 times or more (3Mp or more) of the peak on the lowest molecular weight side is 20% or more. More preferably, it is 40 area% or more. Particularly preferably, it is 60 area% or more.

[0072] The modified conjugated diene copolymer of the present invention preferably contains 0.001 to 6% by weight of a structural unit (A1) derived from a modified vinyl aromatic copolymer, 29 to 99.999% by weight of a structural unit (B1) derived from a conjugated diene compound, and 0 to 70% by weight of a structural unit (C1) derived from an aromatic vinyl compound. The structural unit (A1) derived from the modified vinyl aromatic copolymer (A) is preferably 0.001 to 5% by weight, more preferably 0.005 to 5% by weight, still more preferably 0.01 to 5% by weight, and most preferably 0.001 to 1% by weight. The structural unit (B1) derived from the conjugated diene compound (B) is 29 to 99.999% by weight, preferably 80 to 99.999% by weight, more preferably 90 to 99.995% by weight, and still more preferably 95 to 99.99% by weight. When using the aromatic vinyl compound (C), the structural unit (A1) is in the same range as above, the structural unit (B1) is 30 to 97.999% by weight, preferably 45 to 94.995% by weight, and still more preferably 55 to 89.99% by weight. The structural unit (C1) derived from the aromatic vinyl compound (C) is 2 to 50% by weight, preferably 5 to 45% by weight, and still more preferably 10 to 40% by weight.

[0073] The microstructure (cis, trans, vinyl bond content) of the modified conjugated diene copolymer can be arbitrarily changed by using a polar compound or the like. However, in the state before the terminal is modified, the content of the vinyl bond (1,2-bond) in the conjugated diene unit is preferably 10 to 80 mol%. When the modified conjugated diene copolymer of the present invention is used as a resin composition described later and further crosslinked to be used as an automobile tire, in order to highly balance the rolling resistance performance and wear resistance, 20 to 75 mol% is preferable, 25 to 75 mol% is more preferable, and 25 to 70 mol% is still more preferable. Most preferably, it is 25 to 45 mol%. At this time, the mass ratio of the cis bond to the trans bond in the conjugated diene bond unit is preferably cis bond / trans bond = 1 / 1.1 to 1.5.

[0074] To the polymer solution of the modified conjugated diene copolymer obtained by the above polymerization method, a reaction terminator may be added as necessary. Examples of the reaction terminator include alcohols such as methanol, ethanol, and propanol; organic acids such as stearic acid, lauric acid, and octanoic acid; water, etc.

[0075] After carrying out the polymerization reaction of the modified conjugated diene copolymer, the metals contained in the polymer may be deashed as necessary. As a method for deashing, for example, a method is used in which an oxidizing agent such as water, an organic acid, an inorganic acid, or hydrogen peroxide is brought into contact with the polymer solution to extract the metals, and then the aqueous layer is separated.

[0076] When the modified conjugated diene polymer obtained as described above is obtained as a solution, after adding an antioxidant and additives as necessary, the solvent can be removed and dried by a usual method. Thereby, it can be used as a raw material for the resin composition described later. Specifically, methods such as steam stripping and dehydration drying, direct removal methods using a drum dryer, flushing, and a vent extruder, etc.

[0077] The antioxidant is not particularly limited, and known ones can be used. Examples of the antioxidant include phenolic stabilizers, phosphorus stabilizers, sulfur stabilizers, etc. Specifically, for example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0078] As necessary, as additives, alcohols such as water, methanol, ethanol, and isopropanol may be added to remove or neutralize ionic substances, or carboxylic acids such as stearic acid, oleic acid, myristic acid, lauric acid, decanoic acid, citric acid, and malic acid, aqueous inorganic acid solutions, carbon dioxide gas, etc. may be added.

[0079] The resin composition of the present invention can contain 100 parts by mass of a raw material rubber containing 20 parts by mass or more of a modified conjugated diene polymer and 5 to 200 parts by mass of a filler. The content of the modified conjugated diene polymer in 100 parts by mass of the raw material rubber is 20 parts by mass or more, preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 60 parts by mass or more. When it is 20 parts by mass or more, the filler dispersibility aimed at in the present invention is excellent. When the resin composition of the present embodiment is made into a vulcanized composition, the performance such as tensile properties and viscoelastic properties is excellent. When used as a material for tires, excellent fuel consumption performance, grip performance, abrasion resistance, and rigidity can be obtained in the tires. Further, the content of the modified conjugated diene polymer is preferably 90 parts by mass or less, and more preferably 80 parts by mass or less. By setting it to 90 parts by mass or less, the Mooney viscosity of the unvulcanized resin composition of the present invention is lowered and the processability is improved.

[0080] The raw material rubber other than the modified conjugated diene polymer is not particularly limited, and examples thereof include conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, other conjugated diene copolymers or hydrogenated products thereof, non-diene polymers, natural rubber, and the like.

[0081] Specific examples of the conjugated diene polymer or its hydrogenated product are not particularly limited, and examples thereof include butadiene rubber or its hydrogenated product, isoprene rubber or its hydrogenated product, and the like. Specific examples of the random copolymer of a conjugated diene compound and a vinyl aromatic compound or its hydrogenated product are not particularly limited, and examples thereof include styrene-butadiene copolymer rubber or its hydrogenated product. Specific examples of the block copolymer of a conjugated diene compound and a vinyl aromatic compound or its hydrogenated product are not particularly limited, and examples thereof include styrene-based elastomers such as styrene-butadiene block copolymer or its hydrogenated product, styrene-isoprene block copolymer or its hydrogenated product, and the like. Specific examples of other conjugated diene copolymers or hydrogenated products thereof are not particularly limited, and examples thereof include acrylonitrile-butadiene rubber or hydrogenated products thereof. 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-acrylic acid ester-conjugated diene copolymer rubber, urethane rubber, polysulfide rubber, and the like.

[0082] In the present invention, when the modified conjugated diene polymer is a modified styrene-butadiene rubber, polybutadiene is preferable as the other rubber. When the modified butadiene polymer is a modified polybutadiene, natural rubber or polyisoprene rubber is preferable as the other rubber.

[0083] From the viewpoint of the balance between performance and processing characteristics, the weight average molecular weight of each of the above-described rubber-like polymers is preferably from 2,000 to 2,000,000, and more preferably from 5,000 to 1,500,000. Further, so-called liquid rubbers having a low molecular weight can also be used. These rubber-like polymers may be used alone or in combination of two or more. The weight average molecular weight referred to herein is the weight average molecular weight (Mw) in terms of polystyrene obtained by gel permeation chromatography (GPC) measurement.

[0084] When a large amount of filler is used with respect to the raw rubber, the hardness and modulus increase, and they are adjusted to have desired physical properties according to the application. Within this range, the filler is well dispersed and the processability is good. In tire applications, the filler is preferably 5 to 150 parts by mass, and in footwear applications, it is preferably 30 to 200 parts by mass. Within the range of the present embodiment, it is possible to widely correspond to products from soft to hard.

[0085] In the resin composition of the present invention, it is desirable to contain 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 with respect to 100 parts by mass of the raw rubber.

[0086] As the silica-based inorganic filler contained in the resin composition, it is preferable to use solid particles having SiO2 or silicate as the main component of the structural unit. Here, the main component means a component that occupies 50% by mass or more of the whole, preferably 70% by mass or more, and more preferably 90% by mass or more. Specific examples of the silica-based inorganic filler include inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. The silica-based inorganic filler may be used alone or in combination of two or more. In addition, a silica-based inorganic filler having a hydrophobized surface, a mixture of a silica-based inorganic filler and an inorganic filler other than silica-based can also be used. Among these, silica and glass fiber are preferable, and silica is more preferable. As the silica, dry silica, wet silica, synthetic silicate silica, etc. can be used. Among them, wet silica is preferable because it is more excellent in achieving both improvement of fracture characteristics and wet skid resistance performance. As the silica, silica having a BET specific surface area of 50 to 500 m 2 / g is used. By blending such silica, excellent low fuel consumption, wear resistance, wet skid performance, and handling stability can be obtained. In addition, silica having a high specific surface area, that is, fine particle size silica, may be used and can be dispersed well. As the fine particle size silica, silica having a CTAB (cetyltrimethylammonium bromide) specific surface area of 180 m 2 / g or more and a BET specific surface area of 185 m 2 / g or more can be contained. The average primary particle size is, for example, 25 nm or less. By blending such fine particle size silica, excellent low fuel consumption, wear resistance, wet skid performance, and handling stability can be obtained in the resin composition of the present embodiment. The aggregate size of the fine particle size silica is not particularly limited and can be 30 nm or more. By having such an aggregate size, it is possible to provide excellent reinforcing properties, low fuel consumption, abrasion resistance, wet skid performance, and handling stability while having good dispersibility. The aggregate size is also called the aggregate diameter or the maximum frequency Stokes equivalent diameter, and corresponds to the particle diameter when an aggregate of silica composed of a plurality of primary particles connected in a row is regarded as one particle. The aggregate size can be measured, for example, using a disk centrifuge sedimentation type particle size distribution measuring device such as BI-XDC (manufactured by Brookhaven Instruments Corporation). Specifically, it can be measured by the method described in JP-A-2011-132307. The average primary particle diameter of the fine particle size silica is not particularly limited and is preferably 25 nm or less.

[0087] The blending amount of the above-mentioned fine particle size 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, still 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, based on 100 parts by mass of the rubber component. If it is 5 parts by mass or more, the effects of blending the above-mentioned fine particle silica can be sufficiently obtained. The blending amount of the fine particle size silica is 200 parts by mass or less, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less. If it is 200 parts by mass or less, substantially good processability can be obtained.

[0088] The resin composition of the present invention preferably further contains 5 to 100 parts by mass of silica or carbon black having a BET specific surface area of less than 185 m 2 / g as a reinforcing filler. In the resin composition of the present invention, silica having a BET method nitrogen adsorption specific surface area (N2SA) of less than 185 m 2 / g is preferably used as a reinforcing filler, more preferably silica having a BET method nitrogen adsorption specific surface area of less than 150 m 2 / g is used, and preferably 50 m2 More than / g is used. In this range, the balance between reinforcement and dispersibility is good. Also, depending on the application, those with a suitable particle size are used.

[0089] Examples of carbon black include N110, N220, N330, N339, N550, N660, etc. from the classification of carbon black for rubber by ASTM, and they are selected according to the application. By using carbon black in combination, the reinforcement can be enhanced, and the dry grip performance can be improved when used in tire tread applications. The carbon black preferably has a BET method nitrogen adsorption specific surface area (N2SA) of less than 185 m 2 / g, preferably 30 m 2 / g or more, more preferably in the range of 50 - 130 m 2 / g. In this range, the balance between reinforcement and dispersibility is good. When used in tire tread applications, N220, N330, and N339 are more preferable.

[0090] In the resin composition of the present invention, in addition to the above-mentioned silica, other reinforcing fillers can be used. Other reinforcing fillers are not particularly limited, but the metal oxide as a reinforcing filler is preferably solid particles mainly composed of the chemical formula MxOy (M represents a metal atom, and x and y each represent an integer from 1 to 6). Here, the main component means a component that occupies 50% by mass or more of the whole, preferably 70% by mass or more, and more preferably 90% by mass or more. Examples of the metal oxide include alumina, titanium oxide, magnesium oxide, zinc oxide, etc. Examples of the metal hydroxide as a reinforcing filler include aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, etc. The above-mentioned metal oxides and metal hydroxides as other reinforcing fillers may be used alone or in combination of two or more. Also, mixtures with other inorganic fillers can be used.

[0091] In the resin composition of the present invention, a normal silane coupling agent may be used. The silane coupling agent is not particularly limited, and examples thereof include compounds having both a silica affinity part and a polymer affinity part in the molecule, such as sulfide-based compounds, mercapto-based compounds, vinyl-based compounds, amino-based compounds, glycidoxy-based compounds, nitro-based compounds, chloro-based compounds, and the like. Examples of the sulfide-based 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, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, 3-octanoylthio-1-propyltriethoxysilane, and the like. Examples of the mercapto-based compounds include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the like. Examples of the vinyl-based compounds include vinyltriethoxysilane, vinyltrimethoxysilane, and the like. Examples of amino compounds include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, and the like. Examples of glycidoxy compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and the like. Examples of nitro compounds include 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and the like. Examples of chloro compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, and the like. Examples of other compounds include octyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, hexadecyltrimethoxysilane, and the like.

[0092] These silane coupling agents may be used alone or in combination of two or more. Among these silane coupling agents, from the viewpoint of a large reinforcing effect, sulfur-containing silane coupling agents such as sulfide-based compounds and mercapto-based compounds are preferred, and bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and 3-mercaptopropyltrimethoxysilane are more preferred. The compounding amount of the silane coupling agent is 1 to 20 parts by mass, preferably 2 to 15 parts by mass, based on 100 parts by mass of silica. When the silane coupling agent is compounded within this range, the dispersibility of silica is further improved, the processability is improved, and the performance of the vulcanized rubber such as wear resistance is improved.

[0093] In the resin composition of the present invention, by using a plasticizer, it is possible to adjust the hardness and modulus. The plasticizer is not particularly limited. For example, oils similar to the above-mentioned extender oils can be used. In addition, various natural oils, synthetic oils, low molecular weight polymers, etc. can be used. Further, known processing aids can be used.

[0094] The resin composition of the present invention may be a resin composition further subjected to a crosslinking treatment by adding a vulcanizing agent (crosslinking agent), compounding agent, etc. Such crosslinking agents are not particularly limited. For example, sulfur-based vulcanizing agents, organic peroxides, etc. are used. As the sulfur-based vulcanizing agent, there is no particular limitation. For example, sulfur, morpholine disulfide, etc. are used. As the organic peroxide, for example, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, cumene hydroperoxide, etc. are used. The amount of the vulcanizing agent used is not particularly limited, but it is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the conjugated diene copolymer. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably, for example, 120°C to 200°C, more preferably 140°C to 180°C. If necessary, a vulcanization accelerator or a vulcanization aid may be compounded. The vulcanization accelerator is not particularly limited. For example, those 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. Furthermore, if necessary, a vulcanization aid may be compounded. The vulcanization aid is not particularly limited. For example, zinc oxide, stearic acid, etc. can be used. Additionally, an antioxidant can be used.

[0095] The resin composition of the present invention can be produced by mixing the above components. Regarding the method of mixing a modified conjugated diene-based copolymer, at least one reinforcing filler selected from the group consisting of a silica-based inorganic filler, a metal oxide, a metal hydroxide, and carbon black, and optionally a silane coupling agent, there are no particular limitations. For example, melt-kneading methods using general mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, multi-screw extruders, etc., methods of dissolving and mixing each component and then heating and removing the solvent, etc. can be mentioned. Among these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferable from the viewpoints of productivity and good kneading properties. Also, either a method of kneading the rubber component and various compounding agents at once or a method of mixing them in multiple times is applicable.

[0096] In the present invention, the degree of the polymer concentration ability on the filler surface can be represented by the amount of bound rubber (bound rubber generation ability) of the modified conjugated diene-based polymer at 25°C. The amount of bound rubber in the resin composition after the above-mentioned kneading is preferably 15% by mass or more, more preferably 20% by mass or more, from the viewpoints of improving abrasion resistance and fracture strength.

[0097] The resin composition may be a vulcanized composition vulcanized with a vulcanizing agent. As the vulcanizing agent, for example, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds can be used. Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, polymer polysulfur compounds, etc. When vulcanizing, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, conventionally known materials can be used, for example, vulcanization accelerators such as sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, dithiocarbamate-based, etc. can be mentioned. As the vulcanization aid, zinc white, stearic acid, etc. can be used.

[0098] In the resin composition of the present invention, a softening agent for rubber may be blended in order to improve processability. As the softening agent for rubber, mineral oil, liquid or low molecular weight synthetic softening agent is suitable. The mineral oil-based rubber softening agent called process oil or extender oil, which is used to soften, compatibilize, and improve the processability of rubber, is a mixture of aromatic rings, naphthene rings, and paraffin chains. Those in which the carbon number of the paraffin chain accounts for 50% or more of the total carbon are called paraffin-based, those with 30-45% naphthene ring carbon number are called naphthene-based, and those with more than 30% aromatic carbon number are called aromatic-based. As the rubber softening agent used in the present embodiment, naphthene-based and / or paraffin-based ones are preferable. The blending amount of the rubber softening agent is not particularly limited, but it is preferably 10 to 80 parts by mass, more preferably 20 to 50 parts by mass, based on 100 parts by mass of the conjugated diene copolymer.

[0099] In the resin composition of the present invention, within a range that does not impair the object of the present embodiment, softening agents, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, lubricants, and other various additives other than those described above may be used. Specific examples of the filler include calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, and the like. Examples of the softening agent that may be blended as needed to adjust the hardness and fluidity of the target product include liquid paraffin, castor oil, linseed oil, and the like. Known materials can be applied as the heat stabilizer, antistatic agent, weather stabilizer, antioxidant, colorant, and lubricant.

[0100] The resin crosslinked product of the present invention is obtained by crosslinking the resin composition. For example, a tire can be manufactured by extruding and molding the resin composition according to the shape of the tire (e.g., tread shape), heating and pressurizing this in a vulcanizer to produce a tread, and assembling this tread with other parts. The resin composition of the present invention is excellent in mechanical strength and abrasion resistance when formed into a resin crosslinked product. Therefore, as described above, it can be suitably applied to tire treads such as low fuel consumption tires, large tires, and high performance tires, and structural members such as sidewall members. In addition to structural members, it can also be suitably used for rubber belts, rubber hoses, footwear materials, etc.

Examples

[0101] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In each example, parts are all parts by weight unless otherwise specified, and the evaluation of each physical property was performed by the method shown below.

[0102] 1) Molecular weight, molecular weight distribution, area (%) of multi-branched component, and area (%) of 3 Mp or more For the measurement of molecular weight and molecular weight distribution, GPC (manufactured by Tosoh Corporation, HLC-8220GPC) was used. As analysis columns, two TSKgel MultiporeH XL -M: two, TSKgel G1000H XL : one, and one TSKguardcolumn MP(XL) was used as the guard column. Tetrahydrofuran (THF) was used as the solvent, the flow rate was 1.0 ml / min, the column temperature was 38 °C, and a calibration curve using monodisperse polystyrene was used. In addition, as shown in FIG. 1, the area (%) of the multi-branched component of the modified conjugated diene-based copolymer is the number average molecular weight (2Mp) twice that of Mp when the peak top molecular weight (Mp) of the conjugated diene-based copolymer before condensation with the modified vinyl aromatic-based copolymer of the present invention is used. The molecular weight range of the modified conjugated diene-based copolymer after condensation with the modified vinyl aromatic-based copolymer, the molecular weight range of the modified conjugated diene-based copolymer that becomes the number average molecular weight (3Mp) three times that of Mp, the molecular weight range of the modified conjugated diene-based copolymer that becomes the number average molecular weight (5Mp) five times that of Mp, and the molecular weight range of the modified conjugated diene-based copolymer that becomes the number average molecular weight (10Mp) ten times that of Mp are shown. 2) Structure of modified vinyl aromatic copolymer Using a JNM-LA600 type nuclear magnetic resonance spectrometer manufactured by JEOL Ltd., 13Determined by 13C-NMR and 1 1H-NMR analysis. Chloroform-d1 was used as the solvent, and the resonance line of tetramethylsilane was used as the internal standard.

[0103] 3) Solvent solubility (cyclohexane) 5.0 g of the modified vinyl aromatic copolymer was dissolved in 95.0 g of cyclohexane, filtered through a glass filter, and the filtered glass filter was washed with 30 g of cyclohexane and then vacuum dried at 60 °C. Then, the weight of the polymer fraction on the filter was calculated. When the dry weight of the polymer fraction was less than 0.025 g, it was marked as ○; when it was 0.025 g or more and less than 0.25 g, it was marked as △; when it was 0.25 g or more, it was marked as ×. 4) Mooney viscosity Determined according to JIS K6300-1 with an L-shaped rotor, preheating for 1 minute, rotor operating time of 4 minutes, and temperature of 100 °C. 5) Gel fraction To a sample prepared by dissolving 0.5 g of the copolymer rubber in 100 mL of toluene, 1.0 g of a 0.2 wt% Sudan III toluene solution was added and left 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. The gel fraction colored with Sudan III on the dried membrane filter was visually observed. When the number of gel fractions was 0, it was marked as ○; when it was 1 - 5, it was marked as △; when it was 6 or more, it was marked as ×.

[0104] 6) Thermogravimetric measurement (TGA) Performed according to JIS K7120, and the weight loss at 350 °C (TGA 350 ) was determined. 7) Haze A sample prepared by dissolving 0.5 g of the copolymer rubber in 100 g of toluene was placed in a quartz cell, and its Haze (turbidity) was measured using an integrating sphere type light transmittance measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., SZ-Σ90) with toluene as the reference sample.

[0105] 8) Content of vinyl bonds in the conjugated diene copolymer (SBR) The sample was made into a carbon disulfide solution, and using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm-1. According to the calculation formula of the Hampton (styrene-butadiene copolymer) method based on the absorbance at a predetermined wave number, the vinyl bond content (%) in the conjugated diene copolymer (SBR) was determined. The apparatus used was Spectrum100 manufactured by PerkinElmer. 9) Amount of bound rubber 0.4 g of the unvulcanized rubber after kneading was cut into 2 mm squares, placed in a sample tube together with 50 mL of toluene, and left standing at room temperature for 48 hours. Then, it was extracted with a glass filter, and the toluene solution part and the rubber part were each dried. And the weight of the rubber part on the filter was calculated and taken as the amount of bound rubber. Further, the dried toluene solution part was dissolved in chloroform, the ratio of polybutadiene was calculated by proton NMR, and by back-calculating from the actual compounding parts using this value, the amount of bound rubber of polybutadiene was determined. The amount of bound rubber in Comparative Example 3 was taken as 100 and expressed as an index.

[0106] 10) Tensile strength The 300% modulus was measured by the tensile test method of JIS K6251, and taking the measured value of the crosslinked rubber obtained in Comparative Example 3 as 100, it was expressed as an index. The larger the index value, the better the tensile strength. 11) Abrasion resistance Using the method of using a Lambourne type abrasion tester conforming to JIS K6264, the abrasion amount at a slip rate of 25% was measured, and taking the measured value of the crosslinked rubber obtained in Comparative Example 3 as 100, it was expressed as an index. The measurement temperature was room temperature. The larger the index value, the better the abrasion resistance.

[0107] The raw materials or their abbreviations used in the examples are as follows. DVB-810; a mixture of divinylbenzene component and ethylvinylbenzene component; divinylbenzene component content 81.0 wt%, manufactured by Nippon Steel Chemical & Material

[0108] Example 1 Synthesis of modified vinyl aromatic copolymer (A-1) Charge 300 ml (233.7 g) of cyclohexane and 12.5 ml (86.0 mmol) of co-catalyst triethylamine. At 30 °C, add 66.2 ml of a cyclohexane - hexane solution containing 5.51 g (86.0 mmol) of sec-butyllithium (the following structural formula) as the pure component. After that, [Chemical formula] Add a solution prepared by dissolving 7.19 g of DVB-960 (the structural formulas of divinylbenzene and ethylvinylbenzene are shown below), which has been pre-purified to remove impurities, (52.9 mmol of divinylbenzene (mixture of m- and p-isomers) component, 2.35 mmol of ethylvinylbenzene (mixture of m- and p-isomers) component) in 170 ml (132.4 g) of cyclohexane over 2.0 h. Then, continue stirring at 30 °C for 60 min. [Chemical formula] Next, add 99.7 g (1.38 mol) of co-catalyst tetrahydrofuran. Then, add 87.9 g (1.29 mol) of isoprene (the following structural formula) as a monomer to the reactor over 60 min, and continue stirring at 30 °C for 30 min. [Chemical formula] After the completion of the polymerization reaction, a small sample of the polymerization solution was taken for GC analysis. As a result, no unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. When GPC analysis was performed, the Mn of the copolymer at the end of the second-stage polymerization was 5130, Mw was 6840, and Mw / Mn was 1.33. Next, a solution consisting of 2.15 g (8.6 mmol) of diethylaminomethyltriethoxysilane (DEAMTES), 16.8 g (47.3 mmol) of 1,2-bis(triethoxysilyl)ethane (BTESE), and 200 ml of cyclohexane was added to the polymerization solution obtained by the above polymerization reaction, and a modification reaction was carried out for 2 hours to obtain a modified vinyl aromatic copolymer-containing polymer solution. After completion of the polymerization reaction, 20.3 g (172 mmol) of the neutralizing agent succinic acid was added and stirred, followed by filtration. Here, DEAMTES is a modifier having an amino group simultaneously with an alkoxysilyl group as shown in the following structural formula. [Chemical formula] Also, BTESE is a modifier (polyfunctional condensing agent) having two alkoxysilyl groups as shown in the following structural formula. [Chemical formula] After concentrating the obtained polymerization solution by devolatilization and dissolving it in cyclohexane, no formation of gel or microgel was observed. As a result, 109.23 g (yield: 98.0 wt%) of the modified vinyl aromatic copolymer A-1 was obtained in terms of the solid content yield. The analysis results of the modified vinyl aromatic copolymer A-1 are shown in Table 1.

[0109] The Mn of the obtained modified vinyl aromatic copolymer A-1 was 10850, Mw was 56570, and Mw / Mn was 5.21. GC analysis, 13 C-NMR and 1By performing H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer A-1 contains 3.77 mol% (6.18 wt%) of structural units derived from divinylbenzene, 0.17 mol% (0.27 wt%) of structural units derived from ethylvinylbenzene, 92.07 mol% (78.84 wt%) of structural units derived from isoprene, 0.61 mol% (1.58 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES), and 3.38 mol% (13.13 wt%) of structural units derived from 1,2-bis(triethoxysilyl)ethane (BTESE), and 10.0 functional groups are introduced per molecule of the modified vinyl aromatic copolymer. The condensed structural units represented by the formula (f1) or (f2) derived from BTESE and DEAMTES are 2.58 mol% in the copolymer, and the ratio of the condensed structural units to the structural units derived from all modifiers (including polyfunctional condensing agents) is 64.5%. In the formula (f1) or (f2) derived from BTESE, F1 is a triethoxysilyl group and R1 is an ethylene group. In the formula (f2) derived from DEAMTES, F1 is a diethylamino group and R1 is a methylene group. Since the polyfunctional structural unit (e1) represented by any of the formulas (1) to (3) is 3.66 mol% (5.99 wt%), the polyfunctionality degree (e1 / c) is 0.97. In the formula (1), R2 is phenyl, R3 is hydrogen, and R4 is sec-butyl. The structural unit derived from divinylbenzene having a residual vinyl group contained in the modified vinyl aromatic copolymer (A-1) is 0.11 mol% (0.19 wt%). Furthermore, the weight average condensation degree of the modified vinyl aromatic copolymer A-1 is 8.6. As a result of thermogravimetric measurement (TGA), the weight loss (TGA 350 ) at 350 °C was 0.71 wt%. 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 value measured using an integrating sphere type light transmittance measuring device with toluene as a reference sample was 0.02.

[0110] Synthesis of Modified Vinyl Aromatic Copolymer (B-1) in Comparative Example 1 200 mL (155.8 g) of cyclohexane and 6.68 mL (46.0 mmol) of the co-catalyst triethylamine were charged. At 30°C, 35.4 mL of a cyclohexane - hexane solution containing 2.95 g (46.0 mmol) of sec-butyllithium as the pure component was added. Then, 3.13 g of DVB-960 (23.0 mmol of divinylbenzene (mixture of m- and p-isomers) component, 1.02 mmol of ethylvinylbenzene (mixture of m- and p-isomers) component) from which impurities had been removed in advance was dissolved in 90.7 mL (70.7 g) of cyclohexane, and the resulting solution was added over 2.0 h. Stirring was continued at 30°C for 60 min as it was. Next, 47.0 g (69.0 mmol) of isoprene (the following structural formula) as a monomer was added to the reactor over 60 min, and stirring was continued at 30°C for 30 min as it was. [Chemical formula] After completion of the polymerization reaction, a small sample of the polymerization solution was taken and subjected to GC analysis. As a result, no unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. When GPC analysis was performed, the Mn of the copolymer at the end of the second-stage polymerization was 2660, the Mw was 3230, and the Mw / Mn was 1.21. Next, a solution consisting of 11.47 g (46.0 mmol) of diethylaminomethyltriethoxysilane (DEAMTES) as a modifier and 150 mL of cyclohexane was added to the polymerization solution obtained by the above polymerization reaction, and a modification reaction was carried out for 2 hours to obtain a polymer solution containing a modified vinyl aromatic copolymer. After completion of the polymerization reaction, 10.9 g (92 mmol) of the neutralizing agent succinic acid was added and stirred, and then filtration was performed. The obtained polymerization solution was concentrated by devolatilization and then dissolved in cyclohexane. As a result, no formation of gel or microgel was observed. As a result, 57.74 g (yield: 97.0 wt%) of the modified vinyl aromatic copolymer B-1 was obtained in terms of solid content. The analysis results of the modified vinyl aromatic copolymer B-1 are shown in Table 1.

[0111] The Mn of the obtained modified vinyl aromatic copolymer B-1 was 3480, Mw was 5200, and Mw / Mn was 1.49. By performing GC analysis, 13 C-NMR and 1 H-NMR analysis revealed that the modified vinyl aromatic copolymer B-1 contained 3.03 mol% (5.03 wt%) of structural units derived from divinylbenzene, 0.13 mol% (0.22 wt%) of structural units derived from ethylvinylbenzene, 90.79 mol% (78.96 wt%) of structural units derived from isoprene, and 6.05 mol% (15.79 wt%) of structural units derived from diethylaminomethyltriethoxysilane (DEAMTES). It was confirmed that 2.7 functional groups were introduced per molecule of the modified vinyl aromatic copolymer. The condensed structural unit represented by the above formula (f2) derived from DEAMTES was 0.55 mol% in the copolymer, and the ratio of the condensed structural unit in all the structural units derived from the modifier was 9.1%. In formula (f2), F1 is a diethylamino group and R1 is a methylene group. Since the polyfunctional structural unit (e1) represented by any of the above formulas (1)-(3) was 2.87 mol% (4.78 wt%), the polyfunctionality degree (e1 / c) was 0.95. In formula (1), R2 is phenyl, R3 is hydrogen, and R4 is sec-butyl. The structural unit derived from divinylbenzene having a residual vinyl group contained in the modified vinyl aromatic copolymer (B-1) was 0.15 mol% (0.25 wt%). Furthermore, the weight-average condensation degree of the modified vinyl aromatic copolymer B-1 was 1.6. As a result of thermogravimetric measurement (TGA), the weight loss (TGA 350 ) at 350 °C was 1.02 wt%. A sample obtained by dissolving 0.5 g of the modified vinyl aromatic copolymer (B-1) in 100 g of toluene was placed in a quartz cell, and the Haze value measured using an integrating sphere type light transmittance measuring device with toluene as a reference sample was 0.06.

[0112] Example 2 Synthesis of Modified Vinyl Aromatic Copolymer (C-1) Charge 350 ml (272.7 g) of cyclohexane and 12.5 ml (86.0 mmol) of co-catalyst triethylamine. At 30 °C, add 66.2 ml of a cyclohexane-hexane solution containing 5.51 g (86.0 mmol) of sec-butyllithium as the pure component. Then, add a solution prepared by dissolving 7.68 g of DVB-960 (56.5 mmol of divinylbenzene (mixture of m- and p-isomers) component, 2.51 mmol of ethylvinylbenzene (mixture of m- and p-isomers) component), which has been pre-purified to remove impurities, in 150 ml (116.9 g) of cyclohexane over 2.0 h. Stir continuously at 30 °C for 60 min as it is. Next, add 99.7 g (1.38 mol) of co-catalyst tetrahydrofuran. Then, add 87.9 g (1.29 mol) of isoprene as a monomer to the reactor over 60 min and continue stirring at 30 °C for 30 min as it is. After the completion of the polymerization reaction, a small sample of the polymerization solution was taken for GC analysis. As a result, no unreacted monomer was observed, and it was confirmed that the polymerization conversion rate was almost 100%. When GPC analysis was performed, the Mn of the copolymer at the end of the second-stage polymerization was 5320, Mw was 7120, and Mw / Mn was 1.34. Next, add a solution consisting of 6.07 g (25.8 mmol) of diethylaminopropyltrimethoxysilane (DEAPTMS), 18.3 g (51.6 mol) of 1,2-bis(triethoxysilyl)ethane (BTESE), and 200 ml of cyclohexane as a modifier to the polymerization solution obtained by the above polymerization reaction, and carry out a modification reaction for 2 hours to obtain a modified vinyl aromatic copolymer-containing polymer solution. After the completion of the polymerization reaction, add 20.3 g (172 mmol) of neutralizing agent succinic acid, stir, and then filter. Here, DEAPTMS is a modifier having an amino group simultaneously with an alkoxysilyl group as shown in the following structural formula.

Chemical formula

Chemical formula

[0113] The Mn of the obtained modified vinyl aromatic copolymer C-1 was 9470, the Mw was 30560, and the Mw / Mn was 3.23. By performing GC analysis, 13 C-NMR and 1 H-NMR analysis, it was confirmed that the modified vinyl aromatic copolymer C-1 contains 3.96 mol% (6.30 wt%) of structural units derived from divinylbenzene, 0.18 mol% (0.28 wt%) of structural units derived from ethylvinylbenzene, 90.44 mol% (75.25 wt%) of structural units derived from isoprene, 1.81 mol% (4.49 wt%) of structural units derived from diethylaminopropyltrimethoxysilane (DEAPTMS), and 3.62 mol% (13.68 wt%) of structural units derived from 1,2-bis(triethoxysilyl)ethane (BTESE). It was also confirmed that 10.5 functional groups are introduced per molecule of the modified vinyl aromatic copolymer. The condensation structural unit represented by the formula (f1) or (f2) derived from BTESE and DEAPTMS is 2.17 mol% in the copolymer, and the ratio of the condensation structural unit in all the structural units derived from the modifiers (including multifunctional condensing agents) is 40.0%. In the formula (f1) or (f2) derived from BTESE, F1 is a triethoxysilyl group and R1 is an ethylene group. In the formula (f2) derived from DEAPTMS, F1 is a diethylamino group and R1 is a propylene group. Since the polyfunctional structural unit (e1) represented by any of the formulas (1) to (3) is 3.80 mol% (6.05 wt%), the polyfunctional structure degree (e1 / c) was 0.96. In formula (1), R2 is phenyl, R3 is hydrogen, and R4 is sec-butyl. The structural unit derived from divinylbenzene having a residual vinyl group contained in the modified vinyl aromatic copolymer (C-1) was 0.16 mol% (0.25 wt%). Further, the weight-average condensation degree of the modified vinyl aromatic copolymer C-1 was 4.5. As a result of thermogravimetric measurement (TGA), the weight loss at 350 °C (TGA 350 ) was 0.84 wt%. A sample prepared by dissolving 0.5 g of the modified vinyl aromatic copolymer (C-1) in 100 g of toluene was placed in a quartz cell, and its Haze (turbidity) value, when measured using an integrating sphere type light transmittance measuring device with toluene as a reference sample, was 0.06.

[0114] The analysis results of the copolymers of Example 1 and 2 and Comparative Example 1 are shown in Table 1.

Table 1

[0115] Example 3 Synthesis of Modified Conjugated Diene Copolymer (A-2) A nitrogen-substituted 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-bis(2-tetrahydrofuryl)propane. After adding 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of n-butyllithium as a pure component at 50 °C, 34.29 g of styrene and 80.00 g of 1,3-butadiene, from which impurities had been removed in advance, were added to initiate polymerization. Due to the heat of polymerization, the temperature of the reaction solution increased, and the maximum temperature reached 72 °C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.778 g of the modified vinyl aromatic copolymer (A-1) obtained in Example 1 as an SBR modifier for modifying the obtained styrene-butadiene rubber (SBR) was added, and a modification reaction was carried out. A modification reaction was carried out at a temperature of 60 °C for 30 minutes to obtain a polymer solution. Furthermore, 0.05 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and subjected to a modification reaction for 30 minutes to obtain a polymer solution containing a modified conjugated diene-based copolymer. After adding 0.045 g of 2,6-di-tert-butyl-4-hydroxytoluene as an antioxidant to the obtained polymerization solution, the solvent was removed by steam stripping and then vacuum dried to obtain a modified conjugated diene-based copolymer (modified SBR) A-2. The analysis results of the modified conjugated diene-based copolymer A-2 are shown in Table 2.

[0116] Comparative Example 2 Synthesis of Modified Conjugated Diene-Based Copolymer (B-2) A nitrogen-substituted 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-bis(2-tetrahydrofuryl)propane. At 50 °C, after adding 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of n-butyllithium as a pure component, 34.29 g of styrene and 80.00 g of 1,3-butadiene, the impurities of which had been removed in advance, were added to initiate the polymerization. The temperature of the reaction solution increased due to the heat of polymerization, and the maximum temperature reached 72 °C. After the completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.932 g of the modified vinyl aromatic-based copolymer (B-1) obtained in Example 1 as an SBR modifier for modifying the obtained styrene-butadiene rubber (SBR) was added, and a modification reaction was carried out. A modification reaction was carried out at a temperature of 60 °C for 30 minutes to obtain a polymer solution. Furthermore, 0.05 mmol of 3-glycidoxypropyltriethoxysilane (GPTES) was added and subjected to a modification reaction for 30 minutes to obtain a polymer solution containing a modified conjugated diene-based copolymer. After adding 0.045 g of 2,6-di-tert-butyl-4-hydroxytoluene as an antioxidant to the obtained polymerization solution, the solvent was removed by steam stripping and then vacuum dried to obtain a modified conjugated diene-based copolymer (modified SBR) B-2. The analysis results of the modified conjugated diene-based copolymer B-2 are shown in Table 2.

[0117] Example 4: Synthesis of Modified Conjugated Diene Copolymer (C-2) A nitrogen-substituted 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-bis(2-tetrahydrofuryl)propane. At 50 °C, after adding 15 g of a cyclohexane solution containing 51.2 mg (0.80 mmol) of n-butyllithium as the pure component, 34.29 g of styrene and 80.00 g of 1,3-butadiene, from which impurities had been removed in advance, were added to initiate polymerization. Due to the heat of polymerization, the temperature of the reaction solution increased, and the maximum temperature reached 72 °C. After completion of the polymerization reaction, 15 g of a cyclohexane solution containing 0.652 g of the modified vinyl aromatic copolymer (C-1) obtained in Example 1 as an SBR modifier for modifying the obtained styrene-butadiene rubber (SBR) was added, and a modification reaction was carried out. A modification reaction was carried out at a temperature of 60 °C for 30 minutes to obtain a polymer solution. Furthermore, 0.05 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. After adding 0.045 g of 2,6-di-tert-butyl-4-hydroxytoluene as an antioxidant to the obtained polymerization solution, the solvent was removed by steam stripping and then vacuum dried to obtain a modified conjugated diene copolymer (modified SBR) C-2. The analysis results of the modified conjugated diene copolymer C-2 are shown in Table 2.

[0118]

Table 2

[0119] Example 5 The modified conjugated diene copolymer (modified SBR) A-2 obtained in Example 3, process oil, carbon black, zinc oxide, stearic acid, and an anti-aging agent were compounded and kneaded using a lab plastomill at 155 °C and 60 rpm for 4 minutes. Sulfur and a vulcanization accelerator were added to the obtained kneaded product, and it was kneaded using a lab plastomill at 70 °C and 60 rpm for 1 minute for vulcanization to obtain a crosslinked rubber A-3. The compounding ratios of the respective additives are shown in Table 3, and the physical properties of the obtained crosslinked rubber are shown in Table 4.

[0120]

Table 3

[0121] The additives used are as follows. Silica: manufactured by Evonik Degussa, ULTRASIL 7000 Carbon black: Nitron #200IS manufactured by Shin-Nichi Kasei Carbon Zinc oxide: Zinc oxide No. 2 manufactured by Sakai Chemical Stearic acid: manufactured by Fuji Film Wako Pure Chemical Industries Antioxidant: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: Powder sulfur JIS No. 2 manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator A: Nocceler CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator B: Nocceler DP manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0122] Example 6, Comparative Example 3 Crosslinked rubbers B-3 and C-3 were obtained in the same manner as in Example 5, except that the modified conjugated diene-based copolymers (modified SBR) B-2 and C-2 synthesized in Example 2 or Comparative Example 1 were used instead of the modified conjugated diene-based copolymer (modified SBR) A-2. The physical properties of the obtained crosslinked rubbers are shown in Table 4.

[0123]

Table 4

[0124] According to Table 4, it can be seen that the crosslinked rubber using the modified conjugated diene copolymer (modified SBR) of the example is a material that can contribute to the compatibility of strength and wear resistance, as it has improved dispersibility of the inorganic filler and reduced loss during running, and is excellent in tensile strength and wear resistance, due to its superior round rubber index compared to the comparative example.

Industrial Applicability

[0125] The modified vinyl aromatic copolymer of the present invention is particularly useful as a modifier for conjugated diene copolymers (such as SBR). The crosslinked rubber obtained by containing a filler in the obtained modified conjugated diene copolymer (modified SBR, etc.) and crosslinking it is excellent in the dispersibility of the filler and excellent in mechanical strength and abrasion resistance. Therefore, it is useful as an elastomer material for tires (treads), seismic isolation rubbers, rubber hoses, rubber rollers, footwear materials, etc. 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, sealing material, printing ink, dispersant, etc. in fields such as the electric and electronic industries, aerospace industries, and construction and building industries. The curable resin composition can be processed into films, sheets, and prepregs and used for various optical elements such as plastic optical parts, touch panels, flat displays, film liquid crystal elements, and further optical waveguides and optical lenses. It can also be used as a modifier for modifying the properties such as heat resistance, dielectric properties, adhesiveness / adhesion, and optical 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), wherein the polymer contains a structural unit derived from a polyfunctional vinyl aromatic compound (c), and furthermore, the terminal of the polymer is modified with a modifier having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, in addition, the polymer has a condensed structural unit (f1) or (f2) represented by the following formula (f1) or (f2) condensed by a polyfunctional condensing agent containing an alkoxysilyl group, The modified vinyl aromatic copolymer is characterized in that the average number of functional groups per molecule of the polymer is 3.0 to 20.0, and the number average molecular weight Mn is 500 to 30,000. 【Chemical 1】 Here, F1 represents a functional group having reactivity derived from a modifier or a polyfunctional condensing agent selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group, and R1 represents an aliphatic hydrocarbon group having 1 to 20 carbon atoms. n represents an integer of 1 to 3. Note that Polymer represents the main polymer structural unit derived from the component (a) or the component (b).

2. 5 mol% or more of the structural unit derived from the component (c) is generated by the reaction of the component (c) with an organic alkali metal compound as a polymerization initiator, and has a group R1 derived from the aromatic structure of the component (c), a group R2 derived from other than the aromatic structure of the component (c), and a group R3 derived from the organic alkali metal compound. It is a polyfunctional structural unit (e1) represented by any one of the following formulas (1) to (3), and the polymer is obtained by subjecting a polyfunctional vinyl aromatic compound (c) and an organic alkali metal compound to a polymerization initiation reaction in a molar ratio of polyfunctional vinyl aromatic compound (c) / organic alkali metal compound in the range of 0.5 to 0.

9. The modified vinyl aromatic copolymer according to Claim 1. 【Chemical 2】 Here, R2 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms, R3 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and R4 represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. n represents an integer of 1 to 3. Note that Polymer represents the main polymer structural unit derived from the component (a) or the component (b).

3. It contains 0.5 mol% or more and 35.0 mol% or less of a structural unit derived from a polyfunctional vinyl aromatic compound (c), and 65.0 mol% or more and 99.5 mol% or less of a structural unit derived from one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b). The modified vinyl aromatic copolymer according to claim 1 or 2, characterized in that.

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

5. The modified vinyl aromatic copolymer according to claim 1 or 2, wherein the monovinyl aromatic compound is one or more monomers selected from the group consisting of styrene, vinylnaphthalene, vinylbiphenyl, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, m-ethylvinylbenzene, indene, and p-ethylvinylbenzene.

6. An initiation reaction step of reacting an alkali metal compound as a polymerization initiator with a polyfunctional vinyl aromatic compound (c) in a molar ratio of polyfunctional vinyl aromatic compound (c) / alkali metal compound in the range of 0.5 to 0.9 to generate a polyfunctional carbanion having a plurality of active sites, 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 polyfunctional structural unit (e1) represented by the formula (1) and a vinyl aromatic copolymer having an active end, A terminal modification step of reacting 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, with the active end of the vinyl aromatic copolymer to form a functional group, and at the same time, partially or entirely polymerizing the polymer with a modifier containing an alkoxysilyl group to form a condensed structural unit (f1) or (f2) represented by the formula (f1) or (f2). The method for producing a modified vinyl aromatic copolymer according to claim 1 or 2, characterized by including a terminal modification and polycondensation step.

7. In the coincidence process, after reacting a polyfunctional vinyl aromatic compound (c) with an organic alkali metal compound to generate a polyfunctional carbanion having a plurality of active sites, one or more monomers selected from the group consisting of a monovinyl aromatic compound (a) and a conjugated diene compound (b) are polymerized, and a part or all of the vinyl aromatic copolymer having a plurality of active sites is condensed with a polyfunctional condensing agent having a plurality of reactive functional groups selected from the group consisting of an alkoxysilyl group, an epoxy group, an alkyl halide group, and a vinyl group, with an alkoxysilyl group as an essential functional group, and the terminal is modified 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. A method for producing a modified vinyl aromatic copolymer according to claim 6, characterized in that

8. A modified conjugated diene copolymer, which is a reaction product of a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound and the modified vinyl aromatic copolymer according to claim 1 or 2.

9. The modified conjugated diene copolymer according to claim 8, containing 0.001 to 6% by weight of a structural unit (A1) derived from the modified vinyl aromatic copolymer, 29 to 99.999% by weight of a structural unit (B1) derived from the conjugated diene compound, and 0 to 70% by weight of a structural unit (C1) derived from the aromatic vinyl compound.

10. The modified conjugated diene copolymer according to claim 8, wherein in the differential molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement, when the total area is 100%, the area of the region having a number average molecular weight (Mn) of 3 times or more of the peak on the lowest molecular weight side is 20% or more.

11. A resin composition, characterized in that it contains 0.5 to 200 parts by weight of at least one reinforcing filler selected from the group consisting of a silica-based inorganic filler, a metal oxide, a metal hydroxide, 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 containing a crosslinking agent.

13. A resin crosslinked product, characterized in that it is obtained by crosslinking the resin composition according to claim 12.

14. A structural member, characterized in that it contains the resin crosslinked product according to claim 13.

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