Modified vinyl aromatic copolymer and its method of production, modified conjugated diene copolymer obtained therefrom, composition thereof, cross-linked rubber product, and tire component

Abstract

Provided are: a modified vinylaromatic copolymer having reactivity and solubility which make the copolymer usable in producing copolymer rubbers; and a copolymer rubber material obtained from the modified vinylaromatic copolymer and having all of processability, strength, and homogeneity.　This modified vinylaromatic copolymer is characterized by comprising structural units (a) derived from a divinylaromatic compound and structural units (b) derived from a monovinylaromatic compound, at least some of the structural units (a) being crosslinking structure units (a1), and by including an end modified with a modification group having at least one functional group selected from the group consisting of amino, hydroxyl, and alkoxysilyl groups.

Description

[Technical field]

[0001] The present invention relates to a modified vinyl aromatic copolymer having excellent reactivity in a reaction with a living end of a conjugated diene polymer using an organolithium compound as an initiator in a hydrocarbon solvent, and a method for producing the same, and also to a modified vinyl aromatic copolymer having a branched structure and a method for producing the same, and further to a modified conjugated diene copolymer having excellent processability, tensile strength and abrasion resistance, a modified conjugated diene copolymer composition comprising the modified conjugated diene copolymer, a cross-linked rubber product obtained by cross-linking the modified conjugated diene copolymer, and a tire member. [Background technology]

[0002] Conjugated diene rubbers such as SBR (styrene-butadiene rubber), BR (butadiene rubber), IR (isoprene rubber), and styrene-isoprene rubber have excellent abrasion resistance, elasticity, and water resistance, and are used for a variety of purposes such as molding materials and resin modifiers.

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

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

[0005] For example, in Patent Document 1, an organolithium compound is used as an initiator in a non-polar solvent to synthesize a block copolymer consisting of an α-methylstyrene block and a butadiene block by living anionic polymerization, and if necessary, a polyfunctional coupling agent is reacted to obtain an S-SBR that combines high-temperature characteristics and rubber-like properties. In addition, Patent Document 2 discloses a star-shaped block interpolymer having a random copolymer block of a conjugated diene and a monovinyl aromatic monomer, a polyconjugated diene block, and a functional group derived from a polyfunctional lithium-based initiator, and discloses that the star-shaped block interpolymer can be widely used as a rubber in the manufacture of tire treads having excellent properties such as reduced rolling resistance and improved traction characteristics. The technologies of Patent Documents 1 and 2 are believed to be effective in ensuring the processability of rubber by introducing a branched structure into the rubber component. However, there is no particular ingenuity in the interaction with the filler to ensure strength, and the contribution to strength is insufficient.

[0006] Patent Document 3 discloses a rubber composition in which a rubber composition containing a blend of a plurality of diene rubbers and a predetermined amount of carbon black is blended with a low molecular weight functional group-containing polymer having a functional group at the molecular chain end that interacts with carbon black and having a polymer structure similar to that of the rubber component of the diene rubber. This rubber composition can control the amount of carbon black distributed in each diene rubber component by blending a low molecular weight compound that interacts with carbon black into the rubber. Therefore, it is possible to effectively express the characteristics of each rubber component and achieve a balance between rubber characteristics that are in a trade-off relationship, such as rolling characteristics and wet characteristics. However, this technology does not contribute enough to strength because a low molecular weight compound is blended into the rubber. Patent Document 4 discloses a rubber composition containing a crosslinked rubber particle 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 rubber containing a conjugated diene unit having a specific bond structure, and discloses that the crosslinked rubber particle may contain a monomer unit having a carboxylic acid group, a hydroxyl group, and / or an epoxy group. This technology has an appropriate interaction with an inorganic filler such as silica, and therefore is excellent in dispersibility and processability of the inorganic filler. However, the substances disclosed as the monomer unit having at least two polymerizable unsaturated groups and the monomer unit having a carboxylic acid group, a hydroxyl group, and / or an epoxy group are all low molecular weight. Therefore, there was a risk that the reactivity was excessively high and gelation would progress in the crosslinked rubber particle and the rubber composition. In addition, this technology requires synthesizing a crosslinked rubber separately from the conjugated diene / aromatic vinyl copolymer rubber, and then compounding the crosslinked rubber with the conjugated diene / aromatic vinyl copolymer rubber, and improvement is required from the viewpoint of process simplicity.

[0007] In view of the above problems, the present applicant has discovered that a copolymer rubber having processability, strength, and homogeneity can be provided by using a specific polyfunctional vinyl aromatic copolymer compound, which has both a branched structure and a function of interacting with a filler, as a constituent unit of a conjugated diene rubber (Patent Document 5). Although this polyfunctional vinyl aromatic copolymer compound has a significantly improved gelation resistance, it still has a problem of a small amount of microgel being produced as a by-product.

[0008] The applicant has disclosed compounds similar to the polyfunctional vinyl aromatic copolymer compound disclosed in Patent Document 5 in Patent Documents 6 and 7, etc. However, there is no teaching that these similar compounds can be used as structural units of copolymer rubber. In addition, the polyfunctional vinyl aromatic copolymer disclosed in Patent Document 8 is a copolymer having a wide molecular weight distribution containing a large amount of high molecular weight components with significantly developed branched structures, and therefore, when used as a structural unit of a copolymer rubber, there is a problem that a small amount of microgel is by-produced. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2003-73434 A [Patent Document 2] Special Publication No. 2004-517202 [Patent Document 3] JP 2005-213381 A [Patent Document 4] International Publication No. 2002 / 000779 [Patent Document 5] International Publication No. 2018 / 084128 [Patent Document 6] JP 2004-123873 A [Patent Document 7] JP 2018-39995 A [Patent Document 8] International Publication No. 2018 / 181842 Summary of the Invention

[0010] The present invention aims to solve the above problems and to provide a modified vinyl aromatic copolymer having reactivity and solubility that can be used for producing a modified conjugated diene copolymer without producing a small amount of by-product microgel, a modified conjugated diene copolymer composition that combines processability, strength, and homogeneity, a cross-linked rubber product obtained by cross-linking the same, and a tire component.

[0011] The present inventors have conducted extensive research and found that the above-mentioned problems can be solved by modifying the active end of a vinyl aromatic copolymer having a branch containing a structural unit (a) derived from a specific divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound with an amino group, an alkoxysilyl group, or a hydroxyl group, and thus completed the present invention. In addition, the present inventors have found that a modified vinyl aromatic copolymer obtained by modifying the side chain or end of a multifunctional vinyl aromatic copolymer with a silane compound has high reactivity when producing a modified conjugated diene copolymer, and that the above-mentioned problems can be solved by using this modified conjugated diene copolymer as a structural unit of a modified conjugated diene copolymer composition, and thus completed the present invention.

[0012] The present invention relates to a modified vinyl aromatic copolymer containing a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, wherein at least a part of the structural unit (a) is the following crosslinked structural unit (a1): [ka] (where R 1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. The modified vinyl aromatic copolymer is characterized in that one or more of the terminals is modified with a modifying group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group.

[0013] The present invention also relates to a copolymer comprising a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, the copolymer comprising 0.5 to 95.0 mol % of the structural unit (a) and 5.0 to 99.5 mol % of the structural unit (b) relative to the total of the structural units (a) and (b); The copolymer has a side chain or an end thereof represented by the following formula (c1) or (c2): [ka] (where R 2 is a divalent alkylene group having 1 to 6 carbon atoms, R 3 , R 4 , R 5 , R 7 , R 8 and R 9 each independently represents a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, a benzyloxy group, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a phenyl group, or a benzyl group. 3 , R 4 and R 5 At least one of, or R 7 , R 8 and R 9 At least one of is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, or a benzyloxy group. Contains one or more types of silane-based functional groups (c) represented by the molar fraction of the crosslinking structural unit (a1) relative to the structural unit (a) is in the range of 0.05 to 0.90; The compound has 1 to 20 silane functional groups (c) per molecule, The modified vinyl aromatic copolymer has a number average molecular weight Mn of 500 to 100,000 and a molecular weight distribution (Mw / Mn) expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn of 30.0 or less.

[0014] The modified vinyl aromatic copolymer may contain at least one copolymer represented by any one of the following formulas (2) to (13). [ka] [ka] (In the formula, R 2 is a divalent alkylene group having 1 to 6 carbon atoms, R 3 , R 4 and R 5 is the same as the above formula (c1), and R 6 is an alkyl group having 1 to 6 carbon atoms, a vinyl group, or hydrogen. Polymer is a copolymer chain. R 7 , R 8 and R 9 is the same as the above formula (c2). However, the benzene ring in the formula can be any aromatic ring.

[0015] Examples of the structural unit (b) derived from the monovinyl aromatic compound include structural units derived from 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.

[0016] The present invention also provides a method for producing the modified vinyl aromatic copolymer from a polyfunctional vinyl aromatic copolymer and a silane compound, comprising the steps of: The polyfunctional vinyl aromatic copolymer contains 0.5 mol % or more and 95.0 mol % or less of a structural unit (a) derived from a divinyl aromatic compound, and 5.0 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound; At least a part of the structural unit (a) is the above-mentioned crosslinked structural unit (a1) and the following vinyl group-containing structural unit (a2), [ka] (In the formula, R 1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. the molar fraction of the crosslinking structural unit (a1) relative to the structural unit (a) is in the range of 0.05 to 0.90; the molar fraction of the vinyl group-containing structural unit (a2) relative to the total of the structural units (a) and (b) is in the range of 0.001 to 0.80; A polyfunctional vinyl aromatic copolymer having Mn of 300 to 50,000 and Mw / Mn of 20.0 or less, The silane compound is a silane compound represented by the following formula (15) and / or formula (16): [ka] (where R 2 , R 3 , R 4 and R 5 is the same as the above formula (c1), and R 6 , R 7 and R 8 is R in the above formula (c2) 7 , R 8 and R 9 I agree with that.) The method for producing a modified vinyl aromatic copolymer is characterized in that the above-mentioned polyfunctional vinyl aromatic copolymer and a silane compound are dissolved in a hydrocarbon solvent and added at a temperature of 0 to 150°C in the presence of a catalyst.

[0017] Furthermore, the present invention relates to a modified conjugated diene polymer obtained by reacting a polymer of a conjugated diene compound (B) having an active end, or a copolymer of a conjugated diene compound (B) having an active end and an aromatic vinyl compound (C) with the above-mentioned modified vinyl aromatic copolymer (A) as a modifier.

[0018] The modified conjugated diene copolymer preferably contains 0.001 to 6 weight % of structural units (A1) derived from a modified vinyl aromatic copolymer (A), 29 to 99.999 weight % of structural units (B1) derived from a conjugated diene compound (B), and 0 to 70 weight % of structural units (C1) derived from an aromatic vinyl compound (C). In a differential molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement, the area of ​​a region having a number average molecular weight (Mn) three or more times that of the lowest molecular weight peak is preferably 10% or more, assuming that the total area is 100%.

[0019] The present invention also relates to a modified conjugated diene copolymer composition comprising the above modified conjugated diene copolymer and at least one reinforcing filler selected from the group consisting of a filler or a silica-based inorganic filler, a metal oxide, a metal hydroxide, and carbon black, and this composition may further contain a crosslinking agent.

[0020] The present invention also relates to a cross-linked rubber product obtained by cross-linking the modified conjugated diene copolymer composition, and a tire member comprising the cross-linked rubber product.

[0021] Furthermore, the present invention relates to a modified vinyl aromatic copolymer containing a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, wherein 95 mol % or more of the structural unit (a) is the crosslinked structural unit (a1), The modified vinyl aromatic copolymer is characterized in that two or more of the terminals are modified with a modifying group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group.

[0022] The modified vinyl aromatic copolymer preferably satisfies any one of the following: the structural unit (a) accounts for 0.5 to 95.0 mol % and the structural unit (b) accounts for 5.0 to 99.5 mol % of the structural unit (a) relative to the total of the structural unit (a) and the structural unit (b); the number average molecular weight Mn is 500 to 50,000 and the molecular weight distribution (Mw / Mn) is 10.0 or less; the average number of functional groups per molecule is in the range of 2 to 20; or 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.

[0023] The present invention also relates to a method for producing the modified vinyl aromatic copolymer, which comprises the steps of: a polymerization step of copolymerizing a divinyl aromatic compound and a monovinyl aromatic compound, or a divinyl aromatic compound and a monovinyl aromatic compound and a monomer capable of anionically copolymerizing therewith, using an alkali metal compound or an alkaline earth metal compound as an anionic polymerization initiator to obtain a vinyl aromatic copolymer having a branched structure and an active terminal; and a terminal modification step of reacting the active terminal of the vinyl aromatic copolymer with a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group and a hydroxyl group, or a precursor compound thereof, to form a functional group.

[0024] The present invention also relates to a modified conjugated diene copolymer, which is obtained by reacting a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and an aromatic vinyl compound with the above-mentioned modified vinyl aromatic copolymer.

[0025] The modified conjugated diene copolymer preferably contains 0.001 to 6 weight % of structural units (A1) derived from a modified vinyl aromatic copolymer, 29 to 99.999 weight % of structural units (B1) derived from a conjugated diene compound, and 0 to 70 weight % of structural units (C1) derived from an aromatic vinyl compound, or in a differential molecular weight distribution curve obtained by GPC measurement, the area of ​​a region having a number average molecular weight (Mn) three times or more the lowest molecular weight peak is 10% or more when the total area is taken as 100%.

[0026] Furthermore, the present invention provides a rubber composition characterized by containing 0.5 to 200 parts by weight of at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, per 100 parts by weight of the modified conjugated diene copolymer, and this rubber composition may further contain a crosslinking agent.

[0027] The present invention also relates to a cross-linked rubber product obtained by cross-linking the above rubber composition, and a tire member comprising the cross-linked rubber product. Effect of the Invention

[0028] The modified vinyl aromatic copolymer of the present invention can be used as a raw material for modified conjugated diene copolymers. Furthermore, a crosslinked rubber composition obtained by crosslinking this modified conjugated diene copolymer with a filler has excellent filler dispersibility, mechanical strength, and abrasion resistance, and is therefore useful as an elastomer material for tires (especially tire treads), seismic isolation rubber, rubber hoses, rubber rollers, footwear materials, etc. It can also be applied to molding materials, resin modifiers, etc. It can be provided as a dielectric material, insulating material, heat-resistant material, structural material, etc. in the fields of the electrical and electronic industries, the space and aircraft industries, etc. In addition, the films and sheets coated with the curable resin composition containing the modified vinyl aromatic copolymer of the present invention are suitably used in plastic optical parts, touch panels, flat displays, film liquid crystal elements, etc., and can also be used as a modifier for modifying the properties such as heat resistance, dielectric properties, and optical properties of the thermoplastic resin or curable resin composition used as the main material of the film, sheet, and prepreg. The curable resin composition can also be processed into a film, sheet, and prepreg for use, and can also be used as various optical elements including optical waveguides and optical lenses. [Brief description of the drawings]

[0029] [Figure 1] 1 is a GPC chart of a modified conjugated diene copolymer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The modified vinyl aromatic copolymer of the present invention (hereinafter also referred to as modified copolymer or copolymer) is a modified vinyl aromatic copolymer containing a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, in which at least a part of the structural unit (a) is the above-mentioned crosslinked structural unit (a1), and one or more, preferably one or more, terminals of the copolymer are modified with a modifying group having at least one functional group selected from the group consisting of an amino group, a hydroxyl group and an alkoxysilyl group.

[0031] The modified vinyl aromatic copolymer modified with a modifying group containing an alkoxysilyl group (hereinafter also referred to as modified copolymer or copolymer A) will be described. (First Aspect) The modified vinyl aromatic copolymer contains 0.5 to 95.0 mol % of structural units (a) derived from a divinyl aromatic compound and 5.0 to 99.5 mol % or less of structural units (b) derived from a monovinyl aromatic compound, and contains the crosslinked structural units (a1) as at least a part of the structural units (a). Furthermore, this copolymer has an alkoxysilyl group represented by the above formula (c1) or (c2) on its side chain or terminal. 3 R 4 R 5 At least one of or R 7 R 8 R 9 At least one of them is an alkoxy group. Here, the alkoxy group is a group represented by RO-, where R is an alkyl group, an aralkyl group, or an aryl group, and is preferably a C1 to C12 alkyl group, a benzyl group, or a phenyl group. This alkoxysilyl group is a silane-based functional group, and is therefore also referred to as a silane-based functional group (c) or a structural unit (c). The modified vinyl aromatic copolymer has a number average molecular weight Mn of 500 to 100,000, and Mw / Mn is 30.0 or less.

[0032] The molar fraction of the crosslinked structural unit (a1) in the structural unit (a) is in the range of 0.05 to 0.90, and the number of the structural units (c) per molecule is in the range of 1 to 20, and preferably 2 to 20.

[0033] The molar fraction of the crosslinked structural unit (a1) relative to the structural unit (a) (also referred to as the degree of crosslinking) is in the range of 0.05 to 0.90, with a preferred lower limit of 0.06, and more preferably 0.07. The preferred upper limit is 0.80, and more preferably 0.70. Particularly preferably 0.60, and most preferably 0.50. The optimum range is 0.20 to 0.50. If this molar fraction is smaller than 0.05, the crosslinking degree of the copolymer is small, and therefore when the structural unit (c) is introduced, a crosslinking reaction is likely to occur within the copolymer molecule, and microgels tend to be generated during copolymerization with a conjugated diene compound or the like. On the other hand, if it is larger than 0.90, the molecular weight of the copolymer itself increases, and the molecular weight distribution tends to become broad, so that the wear resistance tends to decrease.

[0034] The modified vinyl aromatic copolymer of the present invention can be obtained by reacting an unmodified polyfunctional vinyl aromatic copolymer with a silane compound represented by the above formula (15) and / or formula (16). In formula (15) and formula (16), R 2 is a divalent alkylene group having 1 to 6 carbon atoms, R 3 , R 4 , R 5 , R 6 , R 7 and R 8 each independently represents a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, a benzyloxy group, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a phenyl group, or a benzyl group. 3 , R 4 and R 5 At least one of these may be a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, or a benzyloxy group.

[0035] Examples of the silane-based compound represented by the above formula (15) include mercaptomethylenemethyldiethoxysilane, mercaptomethylenetriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethylmethoxydimethylsilane, 2-mercaptoethylethoxydimethylsilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 3-mercaptopropyldiethoxymethylsilane, 3-mercaptopropyldimethoxyethylsilane, 3-mercaptopropyldiethoxyethylsilane, 3-mercaptopropylmethoxydimethylsilane, 3-mercaptopropylethoxydimethylsilane, etc. These silane compounds may be used alone or in combination of two or more. The mercapto group (-SH) of the silane compound represented by the above formula (15) undergoes a radical addition reaction with the carbon-carbon unsaturated bond contained in the polyfunctional vinyl aromatic copolymer, thereby obtaining a modified vinyl aromatic copolymer represented by the above formulas (2) to (7) having a structural unit (c) derived from the silane compound.

[0036] Examples of the silane-based compound represented by the above formula (16) include alkoxysilanes such as trimethoxysilane, triethoxysilane, dimethoxymethylsilane, dimethoxychloromethylsilane, methoxydimethylsilane, dimethoxyphenylsilane, and 1,3,3,5,5,7,7-heptamethyl-1,1-dimethoxytetrasiloxane. These silane compounds may be used alone or in combination of two or more. Among these, dimethoxymethylsilane, diethoxymethylsilane, trimethoxysilane, and triethoxysilane are preferred. The hydrosilyl group (-SiH) of the silane compound is added (hydrosilylated) to an unmodified vinyl aromatic copolymer having a carbon-carbon unsaturated bond in the presence of a catalyst containing a Group 8 transition metal, a quinone compound having two or more organic groups each having three or more carbon atoms, and a phenolic compound having at least one functional group selected from the group consisting of an ester group, an ether group, a thioether group, an amide group, a urea group, and a urethane group, to obtain a modified vinyl aromatic copolymer having a structural unit (c) derived from the silane compound and represented by the above formulas (8) to (13).

[0037] In formulas (2) to (13), -R 2 -Si-R 3 R 4 R 5 or -Si-R 7 R 8 R 9is called the silane functional group (c) or structural unit (c). Polymer is a copolymer chain, and the tertiary carbon-containing group and secondary carbon-containing group between it and the silane functional group (c) are groups originating from the end, side chain, and / or center of the copolymer chain. The benzene ring located between the silane functional group (c) and the copolymer chain is included in the units originating from the copolymer chain, and is therefore also a part of the copolymer chain, and this benzene ring may be another aromatic ring.

[0038] The average number of structural units (c) per molecule is 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 9. If this number is less than 1, when the rubber composition is formed, the affinity with the filler (C) is low, and the filler dispersibility in the rubber composition cannot be improved, and for example, physical properties such as abrasion resistance and steering stability may not be improved, or dry grip performance and wet grip performance may be impaired. On the other hand, if it exceeds 20, even the crosslinked product obtained from the rubber composition tends to have poor physical properties such as abrasion resistance or wet grip performance.

[0039] Although the detailed mechanism is unclear, it is presumed that the introduction of an appropriate amount of functional groups into the modified vinyl aromatic copolymer makes it easier for the modified conjugated diene copolymer (hereinafter also referred to as diene copolymer) to concentrate near the reinforcing filler, which increases the reinforcing effect of the reinforcing filler and leads to improved abrasion resistance of the resulting crosslinked product. In addition, it is presumed that the affinity between the diene copolymer and the reinforcing filler is improved by passing through the modified vinyl aromatic copolymer, which is ideal for improving the physical properties (e.g., improved abrasion resistance, improved steering stability, dry grip performance, wet grip performance) of the crosslinked product in which the dispersion state of each component such as the reinforcing filler in the rubber composition is obtained. On the other hand, if the number of functional groups of the modified vinyl aromatic copolymer becomes too large, the modified vinyl aromatic copolymer in the diene copolymer is excessively strongly adsorbed to the reinforcing filler, which reduces the dispersibility of the reinforcing filler and does not contribute to improving the properties (abrasion resistance, strength) of the crosslinked product consisting of the diene copolymer and the reinforcing filler.

[0040] On the other hand, if the number of functional groups in the modified copolymer becomes too large, the copolymer adsorbed to the reinforcing filler will be adsorbed too strongly, which will reduce the dispersibility of the reinforcing filler, and it is presumed that the modified vinyl aromatic copolymer will not contribute to improving the properties (wear resistance, strength) of the crosslinked material consisting of the diene copolymer and the reinforcing filler.

[0041] The average number of functional groups per molecule of the copolymer of the present invention can be calculated by the following formula. (Average number of functional groups per molecule) = [(number average degree of polymerization) * (average molecular weight of one repeating unit)] / (functional group equivalent) The equivalent of a functional group means the mass of the divinyl aromatic compound unit and the monovinyl aromatic compound bonded to one functional group. 1 H-NMR or 13 It can be calculated from the area ratio of the peak derived from the functional group to the peak derived from the polymer main chain using C-NMR. Note that the peak derived from the functional group refers to the peak derived from the alkoxy group.

[0042] In the method for producing the modified vinyl aromatic copolymer of the present invention, the amount of the silane compound represented by the formula (15) and / or the formula (16) used is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, even more preferably 1 to 60 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 1 to 40 parts by mass, per 100 parts by mass of the polyfunctional vinyl aromatic copolymer. If the amount used is more than 200 parts by mass, the dispersibility of the reinforcing filler is poor, the processability is deteriorated, and the abrasion resistance of the obtained crosslinked product tends to decrease. If the amount used is less than 1 part by mass, the dispersibility of the reinforcing filler is poor, and the dispersion state of the reinforcing filler and the like tends not to be ideal for improving the physical properties of the crosslinked product obtained. The amount of the silane compound added to the modified vinyl aromatic copolymer can be determined by using various analytical instruments such as nuclear magnetic resonance spectroscopy.

[0043] The method of adding the silane compound represented by the formula (15) to the polyfunctional vinyl aromatic copolymer is not particularly limited, and for example, the above-mentioned silane compound and, if necessary, a radical catalyst are added to the polyfunctional vinyl aromatic copolymer, and the mixture is heated in the presence or absence of an organic solvent.The radical generator used is not particularly limited, and commercially available organic peroxides, azo compounds, hydrogen peroxide, etc. can be used.

[0044] Examples of the organic peroxides include methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, 2,5-dimethylhexane 2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, and bis(t-butylperoxyisopropyl) Benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2.5-hexanoyl peroxide, lauroyl peroxide, succinic peroxide, benzoyl peroxide and its substituted derivatives, 2,4-dichlorobenzoyl peroxide, meta-toluoyl peroxide, diisopropyl peroxydicarbonate, t-butyl-2-ethylhexanoate, di-2-ethylhexyl peroxydicarbonate, dimethoxyisopropyl peroxycarbonate Examples of peroxyalkylene oxides include tert-butyl peroxycarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, t-butyl peroxyoctanoate, t-butyl peroxy 3,3,5-trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxycarbonate, t-butyl peroxybenzoate, and t-butyl peroxyisobutyrate.

[0045] Examples of the azo compounds include 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(2-(2-imidazolin-2-yl)propane), 2,2'- Examples of the azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), 2,2'-azobis(2-hydroxymethylpropiononitrile), 4,4'-azobis(4-cyanovaleric acid), dimethyl 2,2'-azobis(2-methylpropionate), 2-cyano-2-propylazoformamide, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, and the like.

[0046] The organic solvent used in the above method generally includes hydrocarbon solvents and halogenated hydrocarbon solvents. Among these organic solvents, hydrocarbon solvents such as n-butane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, decalin, benzene, toluene, and xylene are preferred.

[0047] Furthermore, when the reaction for adding the modifying compound is carried out by the above method, an antioxidant may be added from the viewpoint of suppressing side reactions. Examples of the antioxidants that can be used at this time include 2,6-di-t-butyl-4-methylphenol (BHT), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol) (AO-40), 3,9-bis[1,1-dimethyl-2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyl]propionyl], and the like. pionyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane (AO-80), 2,4-bis[(octylthio)methyl]-6-methylphenol (Irganox1520L), 2,4-bis[(dodecylthio)methyl]-6-methylphenol (Irganox1726), 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate (Sumilizer G S), 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (Sumilizer GM), 6-t-butyl-4-[3-(2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yloxy)propyl]-2-methylphenol (Sumilizer GP), tris(2,4-di-t-butylphenyl) phosphite (Irgafos 168), di Examples of such antioxidants include octadecyl 3,3'-dithiobispropionate, hydroquinone, p-methoxyphenol, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (Nocrac 6C), bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate (LA-77Y), N,N-dioctadecylhydroxylamine (Irgastab FS042), bis(4-t-octylphenyl)amine (Irganox 5057), etc. The antioxidants may be used alone or in combination of two or more. The amount of the antioxidant added is preferably 0 to 10 parts by mass, more preferably 0 to 5 parts by mass, based on 100 parts by mass of the unmodified polyfunctional vinyl aromatic copolymer.

[0048] It is not desirable to carry out the reaction of adding a silane compound to a polyfunctional vinyl aromatic copolymer only by heating without using a radical generator. For example, if the heating temperature is too low, the addition reaction does not occur sufficiently, and the average number of functional groups per molecule may not be in the desired range. In addition, if the heating temperature is increased, the addition reaction may proceed, but the polymer polymerization reaction of the polymer may also proceed simultaneously due to the generation of radicals on the polymer main chain, so that if the Mw of the modified vinyl aromatic copolymer is not in the desired range, the viscosity of the copolymer may not be in the desired range. In these cases where the temperature during the addition reaction is high, the handleability of the copolymer may deteriorate due to the high viscosity, or the physical properties of the rubber composition for tires may be adversely affected due to the reduced reactivity with silica. On the other hand, if the addition reaction is carried out using a radical generator, the addition reaction proceeds sufficiently while sufficiently suppressing side reactions such as polymerization reactions even at a relatively low temperature.

[0049] When the maximum peak molecular weight in terms of polystyrene obtained by GPC measurement of the modified vinyl aromatic copolymer is defined as Mt, the total area of ​​the GPC chromatogram obtained by GPC measurement derived from the copolymer is taken as 100%, and the proportion of polymers in the region of molecular weight of Mt×1.45 or more is preferably in the range of 0 to 40%, more preferably in the range of 0 to 30%, even more preferably in the range of 0 to 20%, and particularly preferably in the range of 0 to 10%.

[0050] In the modified vinyl aromatic copolymer of the present invention, the position where the functional group is introduced may be the polymerization terminal or the side chain of the polymer chain, but from the viewpoint of easily introducing multiple functional groups, it is preferable to be the side chain of the polymer chain.In addition, the functional group may be contained alone or may be contained in two or more kinds.Therefore, the copolymer may be modified with one type of modifying compound, or may be modified with two or more types of modifying compounds.

[0051] The mixing ratio of the unmodified polyfunctional vinyl aromatic copolymer and the silane-based compound represented by the formula (15) may be appropriately set so that the average number of functional groups per copolymer molecule is a desired value. For example, the unmodified polyfunctional vinyl aromatic copolymer and the silane-based compound may be mixed so that the mass ratio (former / latter) is 0.3 to 100, and may be mixed so that the mass ratio is, for example, 0.3 to 50.

[0052] As a method for producing the copolymer of the present invention, it is effective to carry out the radical addition reaction of the silane compound represented by the formula (15) at an appropriate reaction temperature for a sufficient reaction time. For example, the temperature in the reaction of adding the silane compound to the polyfunctional vinyl aromatic copolymer is preferably 10 to 200°C, more preferably 50°C to 180°C, and even more preferably 50°C to 140°C. The reaction time is preferably 1 to 200 hours, more preferably 1 to 100 hours, even more preferably 1 to 50 hours, and even more preferably 1 to 25 hours.

[0053] The method for adding the silane compound represented by the formula (16) to the polyfunctional vinyl aromatic copolymer is not particularly limited, and for example, a method can be used in which a silane compound is added (hydrosilylated) to an unmodified vinyl aromatic copolymer having an unsaturated group in the presence of a catalyst containing a Group 8 transition metal in the polyfunctional vinyl aromatic copolymer, a quinone compound having two or more organic groups each having three or more carbon atoms, and a phenolic compound having at least one functional group selected from the group consisting of an ester group, an ether group, a thioether group, an amide group, a urea group, and a urethane group. The silane compound represented by formula (16) is added (hydrosilylated) to an unmodified vinyl aromatic copolymer having a carbon-carbon unsaturated bond, thereby playing the role of introducing a reactive silicon group into the unmodified vinyl aromatic copolymer.

[0054] The amount of the silane compound represented by the formula (16) used depends on the ratio (molar ratio) to the unsaturated groups in the polyfunctional vinyl aromatic copolymer, and the molar ratio (molar number of the silane compound represented by the formula (16) / molar number of the unsaturated groups) is preferably 0.1 to 20, and more preferably 0.5 to 3. The polyfunctional vinyl aromatic copolymer is a polyfunctional vinyl aromatic copolymer having at least one unsaturated group in the molecule capable of addition reaction (hydrosilylation reaction) with a silicon hydride group. The unsaturated group may also be called an unsaturated group having hydrosilylation activity. The number of unsaturated groups having hydrosilylation activity present in one molecule of this polyfunctional vinyl aromatic copolymer is 1 to 20, preferably 1 to 15, more preferably 1 to 10, and particularly preferably 1 to 9.

[0055] The catalyst used when the silane compound represented by the formula (16) is added (hydrosilylated) to a polyfunctional vinyl aromatic copolymer having a carbon-carbon unsaturated bond contains a Group 8 transition metal. Examples of the Group 8 transition metal include cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum.

[0056] Examples of catalysts containing Group 8 transition metals include the above Group 8 transition metals in the form of simple metals, metal salts, or complexes with organic compounds. For example, platinum supported on a support such as alumina, silica, or carbon black; chloroplatinic acid; chloroplatinic acid complexes consisting of chloroplatinic acid and alcohols, aldehydes, ketones, or the like; platinum-olefin complexes [e.g., Pt(CH2=CH2)2(PPh3), Pt(CH2=CH2)2Cl2]; platinum-vinylsiloxane complexes [Pt{(vinyl)Me2SiOSiMe2(vinyl)}, Pt{Me(vinyl)SiO}4]; platinum-phosphine complexes [Ph(PPh3)4, Pt(PBu3)4]; platinum-phosphite complexes [Pt{P(OPh)3}4], and the like are preferred. Also preferred are dicarbonyldichloroplatinum, the platinum-hydrocarbon complexes described in Ashby, U.S. Pat. Nos. 3,159,601 and 3,159,662, and the platinum-alcoholate catalysts described in Lamoreaux, U.S. Pat. No. 3,220,972. Additionally, platinum chloride-olefin complexes as described in Modic, US Pat. No. 3,516,946 are also preferred. Among the catalysts containing the Group 8 transition metals, chloroplatinic acid, platinum-olefin complexes, platinum-acetylacetonate complexes, and platinum-vinylsiloxane complexes are more preferred because of their relatively high reaction activity. The above catalysts may be added to the reaction system either alone or in combination.

[0057] The amount of catalyst added is important in terms of its ratio to the amount of unmodified vinyl aromatic copolymer having carbon-carbon unsaturated bonds added. The molar ratio (moles of catalyst / moles of unsaturated groups) is 10 -1 From 10 -8 is preferred, 10 -3 From 10 -6 More preferably, the molar ratio (moles of catalyst / moles of unsaturated groups) is 10 -8 If the molar ratio is less than 10, the hydrosilylation reaction may not proceed sufficiently. -1 If the content exceeds this range, problems such as an increase in raw material costs and coloring of the product and a decrease in transparency due to contamination with catalyst residues may occur. The method of adding the catalyst is preferably a method of dissolving the catalyst in various solvents and adding the catalyst, because the catalyst can be stabilized, handled easily, etc. The solvent used when the catalyst is dissolved in a solvent and added is not particularly limited, and examples thereof include hydrocarbon solvents such as benzene, toluene, and xylene; halogenated hydrocarbons; alcohols; glycols; ethers; and esters.

[0058] The quinone compound is used in combination with a catalyst and acts as a promoter for the catalyst. The quinone compound is not particularly limited, and examples thereof include 2,5-di-tert-butyl-1,4-benzoquinone, 2,6-di-tert-butyl-1,4-benzoquinone, 1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2,6-dimethyl-1,4-benzoquinone, 2,3,5,6-tetramethyl-1,4-benzoquinone, 2-tert-butyl-1,4-benzoquinone, 1,4-naphthoquinone, and 2-methyl-1,4-naphthoquinone (vitamin K3). Among these, 2,5-di-tert-butyl-1,4-benzoquinone and 2,6-di-tert-butyl-1,4-benzoquinone are preferred in terms of reactivity, coloring inhibition, and toxicity.

[0059] As a method for adding the quinone compound to the reaction system, the quinone compound may be added as it is, but it is preferable to dissolve the quinone compound in a solvent to prepare a uniform diluted solution and then add it, because this is easy to handle and allows the quinone compound to be uniformly dispersed throughout the reaction solution. The addition method may be any of a lump-sum, divided, or continuous method. The solvent used when the quinone compound is diluted in a solvent and added is not particularly limited, and examples thereof include hydrocarbon solvents such as benzene, toluene, xylene, and hexane, halogenated hydrocarbons, alcohols, glycols, ethers, and esters. As disclosed by Jean Fisher et al. (Chem. Eur. J., 4, 2008-2017, (1998)), when an equimolar amount of quinone compound (D) is added to the catalyst, the amount of quinone compound added relative to the catalyst may be small, and the effects of the present invention may not be fully achieved. In addition, the ratio of the amount of the quinone compound to the amount of the unmodified vinyl aromatic copolymer having a carbon-carbon unsaturated bond is also important, and the molar ratio (number of moles of the quinone compound / number of moles of unsaturated groups) is preferably 0.00001 to 100 times, more preferably 0.0001 to 10 times, and particularly preferably 0.001 to 1 time.

[0060] In the production method of the present invention, a phenolic compound having at least one functional group selected from the group consisting of an ester group, an ether group, a thioether group, an amide group, a urea group, and a urethane group in its structure can be used. Phenol-based compounds are used in combination with catalysts and are thought to act as promoters of the catalyst. By adding phenol-based compounds, the hydrosilylation reaction can proceed at a better reaction rate under conditions of addition of a small amount of oxygen than in conventional systems using only a catalyst and a quinone compound. Furthermore, the generation of by-products is suppressed, and it is possible to reduce the amount of catalyst and quinone compound added.

[0061] The phenolic compound is not particularly limited as long as it has at least one functional group selected from the group consisting of an ester group, an ether group, a thioether group, an amide group, a urea group, and a urethane group in its structure, and it is preferable that the compound further has alkyl groups having 1 to 20 carbon atoms as functional groups in the 2- and 6-positions relative to the phenolic hydroxyl group. Examples of such compounds include ester group-containing phenolic compounds such as ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate; thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; Examples of suitable phenolic compounds include phenolic compounds containing an ether group; phenolic compounds containing an amide group such as N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]; and phenolic compounds containing an ether group such as 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-benzopyran-6-ol. Among these, preferred are ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. The phenolic compounds may be used alone or in combination of two or three kinds.

[0062] As a method for adding the phenolic compound to the reaction system, the phenolic compound may be added as it is, but it is preferable to add the phenolic compound as a liquid by heating and melting it, or to add the phenolic compound after dissolving it in a solvent to prepare a uniform diluted solution, because it is possible to disperse the phenolic compound uniformly throughout the reaction liquid. The addition method may be any of a lump-sum, divided, or continuous method. The solvent used when the phenolic compound is diluted in a solvent and then added is not particularly limited, and examples thereof include hydrocarbon solvents such as benzene, toluene, xylene, and hexane, as well as halogenated hydrocarbons, alcohols, glycols, ethers, and esters.

[0063] The ratio of the amount of the phenolic compound to the amount of the organic polymer having an unsaturated group is also important for the amount of the phenolic compound added, and the molar ratio (number of moles of the phenolic compound / number of moles of the unsaturated group) is preferably 0.0002 to 1, more preferably 0.001 to 0.5, and particularly preferably 0.005 to 0.1.

[0064] The hydrosilylation reaction can be carried out in the presence or absence of a solvent. The solvent used in the hydrosilylation reaction is not particularly limited, and examples thereof include hydrocarbons, halogenated hydrocarbons, ethers, and esters. Among these, heptane, hexane, benzene, toluene, and xylene are preferred.

[0065] The hydrosilylation reaction is carried out under an inert gas such as nitrogen or helium to ensure safety in handling flammable substances. However, since oxygen has the effect of accelerating the hydrosilylation reaction, it is preferable to mix oxygen into the inert gas to the extent that it does not result in an explosive mixture composition. The volume fraction of oxygen contained in the gas phase in the reaction vessel is preferably 0.1% or more, more preferably 0.5 to 10%. If the volume fraction of oxygen is less than 0.1%, the effect of promoting the hydrosilylation reaction may not be exhibited. The reaction temperature of the hydrosilylation reaction is preferably 30°C or more and 200°C or less, more preferably 50°C or more and 150°C or less. The reaction time is not particularly limited, but is preferably 30 minutes or more and 15 hours or less, more preferably 30 minutes or more and 10 hours or less, and most preferably 30 minutes or more and 6 hours or less.

[0066] The modified vinyl aromatic copolymer of the present invention contains 0.5 to 95.0 mol % of the structural unit (a) derived from a divinyl aromatic compound. When the structural units are composed only of the structural units (a) and (b), the molar fraction of the structural unit (a) is 0.005 to 0.95 relative to the sum of the structural units (a) and (b). This molar fraction is calculated by the following formula (7). (a) / [(a)+(b)] (7) (wherein (a) is the molar fraction of the structural unit (a) derived from a divinyl aromatic compound, and (b) is the molar fraction of the structural unit (b) derived from a monovinyl aromatic compound.) The lower limit of the molar fraction is preferably 0.006, more preferably 0.007, and the upper limit is preferably 0.80, more preferably 0.70. Optimally, it is from 0.01 to 0.60. In the case where structural units other than the structural units (a) and (b) are contained, the lower limit of the content is preferably 0.2 mol%, more preferably 0.4 mol%, and even more preferably 0.6 mol%, and the upper limit is preferably 70 mol%, more preferably 60 mol%, and even more preferably 50 mol%.

[0067] The modified vinyl aromatic copolymer of the present invention contains 5.0 to 99.5 mol % of the structural unit (b) derived from a monovinyl aromatic compound. In terms of molar fraction, it is 0.05 to 0.995. The preferred lower limit is 0.20. The more preferred lower limit is 0.30. The preferred upper limit is 0.994, more preferably 0.993. The most preferred is 0.40 to 0.99.

[0068] When the polymer consists of only the structural units (a), (b) and (c), the molar fraction of the structural unit (b) is calculated by the following formula (8). (b) / [(a)+(b)] (8) (Here, (a) and (b) are defined as the same as in formula (7).) Even in the case where structural units other than the structural units (a) and (b) are contained, the molar fraction of the structural unit (b) is preferably within the above range.

[0069] The structural unit (a) derived from a divinyl aromatic compound contains a vinyl group as a branching component for exhibiting copolymerization reactivity with a conjugated diene compound, while the structural unit (b) derived from a monovinyl aromatic compound does not contain a vinyl group involved in a curing reaction, and thus provides moldability, compatibility, etc. Furthermore, if the molar fraction of the structural unit (a) is less than 0.005, the heat resistance of the cured product is insufficient, and if it exceeds 0.95, the moldability is reduced. Also, if the molar fraction of the structural unit (b) is more than 0.995, the heat resistance is reduced, and if it is less than 0.05, the moldability is reduced.

[0070] The copolymer of the present invention may contain other structural units in addition to the above structural units, the details of which will be understood from the explanation of the production method.

[0071] The Mn (number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography) of the copolymer of the present invention is 500 to 100,000, preferably 600 to 50,000, more preferably 700 to 40,000. It is further preferably 800 to 30,000, and most preferably 900 to 20,000. It is optimally 900 to 10,000. If Mn is less than 300, the amount of monofunctional copolymer contained in the copolymer increases, so that the copolymerization reactivity with the conjugated diene compound tends to decrease, and if it exceeds 100,000, gel tends to be easily generated, and moldability and tensile elongation at break tend to decrease. The molecular weight distribution is 30.0 or less, preferably 25.0 or less, more preferably 1.3 to 20.0. It is optimally 2.0 to 15.0. If Mw / Mn exceeds 30.0, the processability of the copolymer rubber tends to deteriorate, and gel tends to be generated.

[0072] The 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. In order to be a solvent-soluble, polyfunctional copolymer, it is necessary that some of the vinyl groups of the divinylbenzene are not crosslinked and have an appropriate degree of branching. Such copolymers and their manufacturing methods are known in the above patent documents, etc. Furthermore, it is preferable that the copolymer dissolves in an amount of 50 g or more in 100 g of solvent. More preferably, the copolymer dissolves in an amount of 80 g or more.

[0073] Next, a method for producing an unmodified polyfunctional vinyl aromatic copolymer (also called unmodified copolymer), which is a precursor of the modified vinyl aromatic copolymer of the present invention, will be described. By this method, the copolymer of the present invention can be advantageously produced. In the method for producing the unmodified copolymer, polymerization raw materials including a divinyl aromatic compound and a monovinyl aromatic compound are dissolved in a homogeneous solvent having a dielectric constant of 2.0 to 15.0, and polymerized in the presence of a Lewis acid catalyst at a temperature of 0 to 120°C.

[0074] The divinylaromatic compound makes the copolymer branched and multifunctional, and also plays an important role as a cross-linking component for generating branches when the copolymer is copolymerized with a conjugated diene compound. Examples of the divinylaromatic compound preferably used are divinylbenzene (including each isomer), divinylnaphthalene (including each isomer), and divinylbiphenyl (including each isomer), but are not limited thereto. These can be used alone or in combination of two or more kinds. From the viewpoint of moldability, divinylbenzene (m-isomer, p-isomer, or a mixture of these isomers) is more preferable.

[0075] The monovinyl aromatic compound 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 gelation of the copolymer and improve its solubility in solvents, compatibility, and processability, styrene, ethylvinylbenzene (including each isomer), ethylvinylbiphenyl (including each isomer), ethylvinylnaphthalene (including each isomer), and indene are particularly preferred from the viewpoints of cost and availability. From the viewpoints of compatibility and cost, styrene, ethylvinylbenzene (m-isomer, p-isomer, or a mixture of these isomers), and indene are more preferred.

[0076] In the above-mentioned production method, in addition to the divinyl aromatic compound and the monovinyl aromatic compound, other monomers such as trivinyl aromatic compounds, trivinyl aliphatic compounds, divinyl aliphatic compounds, monovinyl aliphatic compounds, and cycloolefin compounds can be used within the scope of the present invention, and structural units (e) derived from these other monomers can be introduced into the copolymer.

[0077] Specific examples of the other monomers include, but are not limited to, 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, 1,2,4-trivinylcyclohexane, ethylene glycol diacrylate, butadiene, isobutylene, diisobutylene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-methyl-1-cyclopentene, 2-methyl-1-hexene, 1-methyl-1-cyclohexene, 2-methyl-1-heptene, 2-methyl-1-octene, 2-methyl-1-nonene, 2-methyl-1-decene, 2-methyl-1-dodecene, 2-methyl-1-tetradecene, 2-methyl-1-hexadecene, 2-methyl-1-octadecene, 2-methyl-1-eicosene, 2-methyl-1-docosene, and 2-methyl-1-tetracosene. These may be used alone or in combination of two or more. The other monomers are preferably used in an amount of less than 30 mol % of the total monomers, so that the structural units (e) derived from the other monomers are in an amount of less than 30 mol % of the total amount of structural units in the copolymer.

[0078] In the method for producing the unmodified copolymer, a divinyl aromatic compound and a monovinyl aromatic compound, or monomers including other monomers as required, are polymerized in the presence of a Lewis acid catalyst to produce the copolymer.

[0079] The proportion of each monomer component used is preferably within the following range relative to 100 mol % in total of the divinyl aromatic compound and the monovinyl aromatic compound. Divinyl aromatic compound: 0.5 to 95 mol %, preferably 0.3 to 65 mol %, more preferably 0.4 to 55 mol %, optimally 5 to 50 mol %. Monovinyl aromatic compound: 7 to 99 mol %, preferably 10 to 95 mol %, more preferably 15 to 90 mol %.

[0080] The Lewis acid catalyst used here is a compound consisting of a metal ion (acid) and a ligand (base), and can be used without any particular limitation as long as it is capable of accepting an electron pair. Among the Lewis acid catalysts, metal fluorides or complexes thereof are preferred from the viewpoint of thermal decomposition resistance of the copolymer obtained, and in particular, divalent to hexavalent metal fluorides or complexes thereof such as B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, Ti, W, Zn, Fe, and V are preferred. These catalysts can be used alone or in combination of two or more kinds. From the viewpoint of controlling the molecular weight and molecular weight distribution of the copolymer obtained and the polymerization activity, an ether complex of boron trifluoride is most preferably used. Here, examples of the ether complex include diethyl ether and dimethyl ether.

[0081] The Lewis acid catalyst is preferably used in the range of 0.001 to 100 moles, more preferably 0.01 to 50 moles, relative to 100 moles of the total of all monomer components. Most preferably 0.1 to 10 moles. If it exceeds 100 moles, the polymerization rate becomes too high, making it difficult to control the molecular weight distribution. If it is less than 0.001 moles, the polymerization rate becomes too low, resulting in an increase in costs and making it unsuitable for industrial implementation.

[0082] In the above production process, one or more Lewis base compounds may be used as co-catalysts, if desired. Specific examples of the Lewis base compound include the following compounds. 1) Ester compounds such as ethyl acetate, butyl acetate, phenyl acetate, and methyl propionate, 2) Thioester compounds such as methyl mercaptopropionic acid and ethyl mercaptopropionic acid, 3) Ketone compounds such as methyl ethyl ketone, methyl isobutyl ketone, and benzophenone, 4) Amine compounds such as methylamine, ethylamine, propylamine, butylamine, cyclohexylamine, methylethylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; 5) Ether compounds such as diethyl ether and tetrahydrorane, 6) Thioether compounds such as diethyl sulfide and diphenyl sulfide, and 7) Phosphine compounds such as tripropylphosphine, tributylphosphine, trihexylphosphine, tricyclohexylphosphine, trioctylphosphine, vinylphosphine, propenylphosphine, cyclohexenylphosphine, dialkenylphosphine, and trialkenylphosphine. Among these, ester compounds and ketone compounds are preferably used because they act synergistically with the Lewis acid catalyst and can easily control the polymerization rate and the molecular weight distribution of the polymer. These Lewis base compounds can be used alone or in combination.

[0083] During polymerization, the Lewis base compound, which is the cocatalyst component, coordinates with the Lewis acid catalyst, which is the counter anion, and controls the interaction between the carbocation, which is the active species, and the counter anion, thereby adjusting the relative reaction frequency between the propagation reaction and the chain transfer reaction, and contributing to the control of the amount of the reaction.Usually, by adding the Lewis base compound, the interaction between the carbocation, which is the active species, and the counter anion is strengthened, so that the divinyl aromatic compound and the monovinyl aromatic compound are prevented from causing excessive insertion reaction, and the chain transfer reaction after the monomer insertion reaction is easily caused, so that the molecular weight is prevented from increasing excessively, and the molecular weight is easily controlled.

[0084] The amount of the Lewis base compound as the co-catalyst is preferably 0.005 to 500 mol, more preferably 0.01 to 200 mol, and more preferably 0.1 to 100 mol, per 100 mol of the total of all monomers. Within the above range, the polymerization rate is appropriately maintained and at the same time, the selectivity of the reaction between the monomers is improved, resulting in excellent productivity and suppressing excessive increase or decrease in molecular weight, thereby obtaining a copolymer with excellent moldability.

[0085] The polymerization reaction is carried out by cationic copolymerization at a temperature of 20 to 120° C. in a homogeneous solvent in which the polymerization raw materials containing the above-mentioned monomer mixture and Lewis acid catalyst are dissolved in a solvent having a dielectric constant of 2.0 to 15.0.

[0086] The solvent is a compound that does not essentially inhibit cationic polymerization, and dissolves the catalyst, polymerization additive, cocatalyst, monomer, and the vinyl aromatic copolymer to be produced to form a homogeneous solution, and is preferably an organic solvent having a dielectric constant in the range of 2.0 to 15.0, and may be used alone or in combination of two or more. If the dielectric constant of the solvent is less than 2.0, the molecular weight distribution becomes broad, which is not preferable, and if it exceeds 15.0, the polymerization rate decreases.

[0087] As the organic solvent, toluene, xylene, n-hexane, cyclohexane, methylcyclohexane or ethylcyclohexane are particularly preferred from the viewpoint of the balance between polymerization activity and solubility. The amount of the solvent used is determined so that the concentration of the copolymer in the polymerization solution at the end of polymerization is 1 to 90 wt%, preferably 10 to 80 wt%, and particularly preferably 20 to 70 wt%, taking into consideration the viscosity of the resulting polymerization solution and the ease of heat removal. If the concentration is less than 1 wt%, the polymerization efficiency is low, leading to an increase in costs, and if it exceeds 90 wt%, the molecular weight and molecular weight distribution increase, leading to a decrease in moldability.

[0088] When producing an unmodified copolymer, it is necessary to carry out the polymerization at a temperature of 20 to 120° C., preferably 40 to 100° C. If the polymerization temperature exceeds 120° C., the selectivity of the reaction decreases, resulting in problems such as an increase in molecular weight distribution and the generation of gel, while if the polymerization is carried out at a temperature below 20° C., the catalytic activity decreases significantly, making it necessary to add a large amount of catalyst.

[0089] After the polymerization reaction has been stopped, the method for recovering the copolymer is not particularly limited, and for example, a commonly used method such as a heat concentration method, a steam stripping method, or precipitation in a poor solvent may be used.

[0090] The unmodified copolymer obtained by the above production method contains the structural unit (a) derived from the divinyl aromatic compound and the structural unit (b) derived from the monovinyl aromatic compound, and at least a part of the structural unit (a) derived from the divinyl aromatic compound exists as the vinyl group-containing structural unit (a1) represented by the above formula (1), and is soluble in toluene, xylene, tetrahydrofuran, dichloroethane or chloroform. The copolymer of the present invention synthesized from the unmodified copolymer has a reactive silane functional group, so it may be molded and cured by itself, but it is better to use other polymerizable resins for modification and synthesis of high molecular weight multi-branched components. In particular, the modified vinyl aromatic copolymer of the present invention is used for modification and synthesis of high molecular weight multi-branched components when obtaining a conjugated diene copolymer (rubber) obtained by copolymerizing a conjugated diene compound alone and / or a conjugated diene compound with other monomers.

[0091] Next, a modified vinyl aromatic copolymer in which two or more terminals are modified with a modifying group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group will be described. (Second embodiment) The modified vinyl aromatic copolymer of the present invention (hereinafter also referred to as modified copolymer or copolymer A') is a copolymer containing a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, in which 95 mol % or more of the structural unit (a) is a crosslinked structural unit (a1) represented by the above formula (1). At least two of the terminals are modified with a modifying group having the above functional group.

[0092] The divinyl aromatic compound unit (a) contained in the modified vinyl aromatic copolymer plays an important role as a crosslinking component that makes the copolymer branched and multifunctional. When the multifunctional modified vinyl aromatic copolymer is used to modify polymers of conjugated diene compounds, a high molecular weight multi-branched component is generated, which makes it possible to improve the abrasion resistance. Examples of the divinyl aromatic compound preferably include, but are not limited to, divinylbenzene (including each isomer), divinylnaphthalene (including each isomer), and divinylbiphenyl (including each isomer). These may be used alone or in combination of two or more. From the viewpoint of moldability, divinylbenzene (m-isomer, p-isomer, or a mixture of these isomers) is more preferred.

[0093] On the other hand, monovinyl aromatic compounds improve the solvent solubility, compatibility, and processability of the copolymer. Examples of monovinyl aromatic compounds 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 gelation of the copolymer and improve its solubility in solvents, compatibility, and processability, styrene, ethylvinylbenzene (including each isomer), ethylvinylbiphenyl (including each isomer), ethylvinylnaphthalene (including each isomer), and indene are particularly preferred from the viewpoints of cost and ease of availability. From the viewpoints of compatibility and cost, styrene, ethylvinylbenzene (m-form, p-form, or a mixture of these isomers), and indene are more preferred.

[0094] The modified copolymer can be produced by the production method of the present invention. The production method of the present invention includes a polymerization step of copolymerizing a divinyl aromatic compound and a monovinyl aromatic compound, or a divinyl aromatic compound and a monovinyl aromatic compound and a monomer anionically copolymerizable therewith, using an alkali metal compound or an alkaline earth metal compound as an anionic polymerization initiator to obtain a vinyl aromatic copolymer having a branched structure and active terminals, and a terminal modification step of forming the above-mentioned functional group at the active terminal of the vinyl aromatic copolymer. Here, the anionically copolymerizable monomer improves the toughness and compatibility of the copolymer. Examples of the anionically copolymerizable monomer include butadiene, isoprene, 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and conjugated dienes (b1) other than butadiene and isoprene, such as chloroprene. As the anionically copolymerizable monomer contained in the modified vinyl aromatic copolymer of the present invention, butadiene and isoprene are preferred from the viewpoint of ease of industrial implementation.

[0095] The vinyl aromatic copolymer having the branched structure and active end is a multi-branched vinyl aromatic copolymer whose active end is unmodified, and is also the precursor of the modified copolymer of the present invention.In the method for producing the vinyl aromatic copolymer having the branched structure and active end, in addition to the divinyl aromatic compound and the monovinyl aromatic compound, other monomers such as trivinyl aromatic compound can be used within the range that does not impair the effect of the present invention, and the structural unit (e) derived from these other monomers can be introduced into the copolymer.

[0096] Specific examples of the other monomers include, but are not limited to, 1,3,5-trivinylbenzene, 1,3,5-trivinylnaphthalene, etc. These may be used alone or in combination of two or more. The other monomers are preferably used in an amount of less than 30 mol% of the total monomers. Thereby, the structural unit (e) derived from the other monomers is set to be less than 30 mol% of the total amount of structural units in the copolymer.

[0097] In the method for producing the unmodified polyfunctional vinyl aromatic copolymer, the copolymer is produced by polymerizing a divinyl aromatic compound and a monovinyl aromatic compound, or monomers including other monomers as required, in the presence of a polymerization initiator comprising an alkali metal compound or an alkaline earth metal compound.

[0098] At least a portion of the structural unit (a) is the crosslinked structural unit (a1) represented by the above formula (1), and the molar fraction (also referred to as the degree of crosslinking) indicating the proportion of the crosslinked structural unit (a1) derived from the divinyl aromatic compound to the structural unit (a) is 0.95 or more. The degree of crosslinking of the crosslinked structural unit (a1) is in the range of 0.95 or more, with the lower limit being preferably 0.98 or more, and more preferably 0.99 or more.

[0099] The degree of crosslinking is a parameter that can be controlled and changed as desired. If the degree of crosslinking is less than 0.95, a large number of highly reactive pendant vinyl groups will remain in the modified copolymer of the present invention. When this polymer is used to modify a conjugated diene (co)polymer, intramolecular crosslinking reactions are likely to occur starting from the pendant vinyl groups remaining in the copolymer due to the heat history or the like in the subsequent process, and microgels will tend to form during compounding or vulcanization.

[0100] The method for producing the modified copolymer includes the polymerization step and the terminal modification step as described above. The polymerization initiator comprising an alkali metal compound or an alkaline earth metal compound used in the polymerization step will be described below. The alkali metal compound used as the polymerization initiator is not particularly limited, but is preferably, for example, an organolithium compound. The organolithium compound may be any of low molecular weight organolithium compounds and solubilized oligomeric organolithium compounds. Examples of the organolithium compound include a compound having a carbon-lithium bond in the bonding mode between the organic group and lithium, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond. The use of an organolithium compound provides good initiation efficiency and a good living rate of the polymer. The organolithium compound is not particularly limited, but examples of the organolithium compound include an organomonolithium compound, an organodilithium compound, and an organopolylithium compound. As the organic group, a hydrocarbon containing a functional group is suitable, which has the advantage of being excellent in solubility in an organic solvent and also has a good initiation rate. In addition, by using a compound having a nitrogen-lithium bond or a compound having a tin-lithium bond, a modified group containing a functional group can be added to the initiation terminal. The organic alkali metal compound other than the organic lithium compound is not particularly limited, but examples thereof include organic sodium compounds, organic potassium compounds, organic rubidium compounds, and organic cesium compounds. More specifically, sodium naphthalene and potassium naphthalene are included. Other examples include alkoxides, sulfonates, carbonates, and amides of lithium, sodium, potassium, and the like. In addition, the organic alkali metal compound may be used in combination with other organic metal compounds.

[0101] Examples of the alkaline earth metal compound include organic magnesium compounds, organic calcium compounds, and organic strontium compounds. In addition, compounds such as alkoxides, sulfonates, carbonates, and amides of alkaline earth metals may be used. These organic alkaline earth metal compounds may be used in combination with the above-mentioned alkali metal compounds or other organic metal compounds.

[0102] The alkali metal compound having a functional group that can be used as a polymerization initiator is not particularly limited, but includes, for example, a lithium amide compound obtained by lithiating hydrogen of a secondary amine, and an alkyl lithium to which the functional group is bonded. These can provide a functional group to the polymerization initiation terminal of a conjugated diene copolymer. The functional group is not particularly limited, but a functional group that is inactive against alkali metals is preferred, for example, a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, or a protected amino group. In addition, the protected monosubstituted amino group or the protected amino group can be, for example, one hydrogen of a monosubstituted amino group or two hydrogens of an amino group are substituted with a trialkylsilyl group.

[0103] The organolithium compound is not particularly limited, and examples thereof include mono-organolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene. Among these, mono-organolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred. is preferred.

[0104] The polymerization initiator having a functional group is not particularly limited, but specific examples include the compounds shown below. The type of functional group that can be imparted to the polymer is shown in parentheses. For example, there are dipropylaminolithium, diisopropylaminolithium, dibutylaminolithium, tetramethyleneiminolithium, pentamethyleneiminolithium, hexamethyleneiminolithium, heptamethyleneiminolithium, 2-dimethylaminoethyllithium, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-dimethylaminobutyllithium (all of which are disubstituted amino groups), 2-trimethylsilylethylaminoethyllithium, 3-trimethylsilylmethylaminopropyllithium (all of which are monosubstituted amino groups), 2-bistrimethylsilylaminoethyllithium, and 3-bistrimethylsilylaminopropyllithium (all of which are amino groups).

[0105] As the polymerization initiator, an oligomer initiator in which various lithium-based initiators react with a monomer can be used. In this case, a monomer having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group can be used. The oligomer initiator is not particularly limited, but a molecular weight of 1000 or less is preferable because it is easy to handle industrially. It is possible to carry out polymerization or copolymerization using a polymerization initiator having a functional group, and in the next step, introduce 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 compound forming at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, into the active terminal of the vinyl aromatic copolymer.

[0106] The polyfunctional initiator is not particularly limited, but specifically includes an organic dilithium compound and an organic polylithium compound. The organic group is not particularly limited, but a hydrocarbon is preferable. This has the advantage of excellent solubility in organic solvents and also excellent initiation speed.

[0107] The method for preparing the polyfunctional initiator is not particularly limited, but may be a method in which a dispersion of metallic lithium is reacted with a polyhalogenated hydrocarbon compound.

[0108] In the polymerization step, a polar compound may be added. The addition of a polar compound is involved in the initiation reaction and propagation reaction, and is effective in controlling the molecular weight and molecular weight distribution, and in promoting the polymerization reaction. Examples of polar compounds include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium tert-amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more. The amount of polar compound used is not particularly limited and can be selected according to the purpose. Usually, it is preferably 0.01 to 100 moles per mole of polymerization initiator or polyfunctional initiator. Such polar compounds can be used as regulators for the initiation reaction and propagation reaction of the copolymer in an appropriate amount according to the desired molecular weight and molecular weight distribution. Many polar compounds simultaneously have an effective randomizing effect in the copolymerization of a divinyl aromatic compound and a monovinyl aromatic compound, and can be used as an adjuster for the distribution of aromatic vinyl compounds or the amount of styrene blocks.

[0109] The copolymerization of the divinyl aromatic compound and the monomer containing the monovinyl aromatic compound is preferably carried out by solution polymerization in an inert solvent. The polymerization solvent is not particularly limited, and for example, a hydrocarbon-based solvent such as a saturated hydrocarbon or an aromatic hydrocarbon is used. Specifically, the hydrocarbon-based solvent includes 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 mixtures thereof. The monomer and the polymerization solvent are preferably treated with an organometallic compound either alone or in the form of a mixture thereof. This allows the monomers such as divinyl aromatic compounds and monovinyl aromatic compounds, and the allenes and acetylenes contained in the polymerization solvent to be treated. As a result, a polymer having a high concentration of active ends can be obtained, and a high modification rate can be achieved.

[0110] The polymerization temperature during copolymerization is not particularly limited as long as it is a temperature at which living anionic polymerization proceeds, but from the viewpoint of productivity, it is preferably 0°C or higher, and from the viewpoint of ensuring a sufficient reaction amount of active terminals in the terminal modification step after the completion of polymerization, it is preferably 120°C or lower, and more preferably 50 to 100°C.

[0111] The polymerization reaction can be carried out in any manner, including but not limited to a batchwise manner (also called a "batch type") and a continuous manner. In a continuous manner, one or more connected reactors can be used. The reactor used may be a tank type or a tube type equipped with an agitator. In a batchwise manner, the molecular weight distribution of the polymer obtained is generally narrow, and Mw / Mn tends to be 1.0 or more and less than 1.8. In a continuous manner, the molecular weight distribution is generally wide, and Mw / Mn tends to be 1.8 or more and less than 3.

[0112] [Terminal modification step] In the production method of the present invention, a vinyl aromatic copolymer (also referred to as an unmodified copolymer) having a branched structure and an active terminal is obtained in a polymerization step, and then the copolymer is subjected to a terminal modification step in which the active terminal is reacted with a compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, or a compound forming at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, to introduce the functional group.

[0113] The reaction temperature, reaction time, and the like when reacting the compound (including the precursor) having the functional group at the active terminal are not particularly limited, but it is preferable to react at 0 to 120° C. for 30 seconds or more. The amount of the compound having the functional group added is not particularly limited, but the number of moles of the polymerization initiator or polyfunctional initiator, i.e., the total number of moles of the compound having the functional group relative to the number of polymer molecules, is preferably in the range of 0.01 to 6 times, more preferably in the range of 0.02 to 3 times, and even more preferably in the range of 0.05 to 2 times. If the amount of addition is 0.05 times or more, it is preferable from the viewpoint of obtaining a sufficient modification rate in the target modified vinyl aromatic copolymer. In such a case, the amount of the compound having the functional group added is preferably 0.7 or less times, in terms of functional group equivalent, the number of moles of the polymerization initiator or polyfunctional initiator, that is, the number of polymer molecules.

[0114] In the case where the polymerization process is a batch process, the terminal modification process may be carried out in the reactor used in the polymerization process, or may be carried out in a subsequent reactor. In the case where the polymerization process is a continuous process, the terminal modification process is carried out in a subsequent reactor. The terminal modification process is preferably carried out immediately following the polymerization process, and the modifying agent is mixed and the reaction is carried out preferably within 5 minutes. The reactor for the modification reaction is preferably one that can perform sufficient stirring. Specifically, there are a static mixer type reactor, a stirrer-equipped tank type reactor, and the like.

[0115] The terminal modification step is a step of reacting an active terminal of an unmodified copolymer with a compound (including its precursor, which is also called a modifying compound) having at least one functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group to form a bond, or reacting with such a modifying compound to modify the terminal terminal. In the modifying compound used in this step, the functional group to be bonded to the active terminal of the conjugated diene polymer is not particularly limited, but specific examples thereof include a halogen group, a double bond, a ketone group, an ester group, an amide group, an epoxy group, and an alkoxysilyl group.

[0116] Among the modified compounds, the compound having an amino group is not particularly limited, but specifically includes a compound having an amino group and a functional group that bonds with the active terminal of a polymer in the molecule, and preferably does not have active hydrogen.The amino group is not particularly limited, but specifically, a functional group that is inactive to alkali metals is preferred, and a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, and an amino group with two hydrogens protected are preferred.In addition, examples of a protected monosubstituted amino group or an amino group with two hydrogens protected include those in which one hydrogen of a monosubstituted amino group or two hydrogens of an amino group are respectively substituted with a trialkylsilyl group.

[0117] The compound having an alkoxysilyl group is not particularly limited, but specifically includes a compound having multiple alkoxysilyl groups in the molecule (including a compound having a silyl group with multiple alkoxy groups bonded thereto), and a compound having an alkoxysilyl group in the molecule and a functional group bonded to the polymer active end.It is preferable that these are compounds that do not have active hydrogen.

[0118] The compound that forms a hydroxyl group is not particularly limited, but specific examples include a compound having a functional group that bonds with the active terminal of the polymer and generates a hydroxyl group after a bonding reaction, and a compound having a functional group that does not bond with the active terminal of the polymer and generates a hydroxyl group later by a reaction such as hydrolysis, and it is preferable that the compound does not have active hydrogen. Examples of the compound having a functional group that generates a hydroxyl group after the above-mentioned bonding 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 bonding reaction include compounds having an alkoxysilyl group, an aminosilyl group, etc.

[0119] Specific examples of the modifying compound are shown below. The compound that bonds with the active end of the unmodified copolymer to form an amino group at the end of the polymer is not particularly limited, but examples thereof include C=N double bond compounds such as N,N'-dicyclohexylcarbodiimide. The compound that forms an amino group and a hydroxyl group at the terminal of the copolymer 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) and N,N,N',N'-tetraethyl-4,4'-diaminobenzophenone; cyclic urea compounds, such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; cyclic amides, i.e., lactam compounds; amino group-containing epoxy compounds, such as N,N,N',N'-tetraglycidyl-1,3-bisaminomethylcyclohexane; and epoxy compounds having a nitrogen-containing heterocyclic group as described in JP2001-131227A. The compound that forms an alkoxysilyl group at the end of the copolymer is not particularly limited, but examples thereof include halogenated alkoxysilane compounds such as trimethoxychlorosilane, triethoxychlorosilane, and diphenoxydicyrosilane; and polyfunctional alkoxysilane compounds such as bis(trimethoxysilyl)ethane and bis(3-triethoxysilylpropyl)ethane. The compound that forms an alkoxysilyl group and a hydroxyl group at the end of the copolymer is not particularly limited, but examples thereof include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and polysiloxane compounds having an epoxy group and an alkoxysilyl group in the molecule.

[0120] The compound that forms an amino group and an alkoxysilyl group at the terminal of the copolymer is not particularly limited, and examples thereof include alkoxysilane compounds to which an alkyl group having an amino substituent is bonded, such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminopropyltriethoxysilane, bis(3-trimethoxysilylpropyl)methylamine, and bis(3-triethoxysilylpropyl)methylamine; alkoxysilane compounds having a protected mono-substituted amino group bonded thereto, such as N-[2-(trimethoxysilanyl)-ethyl]-N,N',N'-trimethylethane-1,2-diamine, 1-[3-(triethoxysilanyl)-propyl]-4-methylpiperazine, and the like. , 2-(trimethoxysilanyl)-1,3-dimethylimidazolidine, bis-(3-dimethylaminopropyl)-dimethoxysilane, and other alkoxysilane compounds having a plurality of substituted amino groups bonded thereto, as described in WO2008 / 013090A; alkoxysilane compounds having a nitrogen-containing heterocycle bonded thereto, as described in WO2011 / 040312A, such as 1,4-bis[3-(trimethoxysilyl)propyl]piperazine, 1,4-bis[3-(triethoxysilyl)propyl]piperazine; 3-[N, Examples include alkoxysilane compounds having an azasilane group bonded thereto, such as N-bis(trimethylsilyl)amino]propyltrimethoxysilane, 3-[N,N-bis(trimethylsilyl)amino]propylmethyldiethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, and 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, which are described in WO2011 / 129425A. The compound that forms a hydroxyl group at the end of the copolymer is not particularly limited, but examples thereof include epoxy compounds such as ethylene oxide and propylene oxide; and ketone compounds such as benzophenone.

[0121] The modified copolymer of the present invention or the modified vinyl aromatic copolymer of the present invention obtained by the above-mentioned production method has reactive functional groups, so it may be molded and cured alone, but it is better to use other polymerizable resins for functional group modification and synthesis of high molecular weight multi-branched components.In particular, this modified copolymer is used for functional group modification and synthesis of high molecular weight multi-branched components when a conjugated diene compound is copolymerized alone and / or a conjugated diene compound is copolymerized with other monomers to obtain a conjugated diene copolymer (also called modified rubber).

[0122] The modified copolymer of the present invention is excellent as a modifier for conjugated diene (co)polymer (rubber). Although the detailed mechanism is unclear, it is presumed that the modified copolymer of the present invention has an appropriate amount of functional groups introduced therein, so that the rubber is modified to become a modified conjugated diene copolymer (modified rubber), which tends to concentrate near the reinforcing filler, and the reinforcing effect of the reinforcing filler is increased, leading to an improvement in the abrasion resistance of the obtained crosslinked product. In addition, it is presumed that the affinity between the modified copolymer of the present invention and the reinforcing filler is improved by using the modified rubber, and the dispersion state of each component, such as the reinforcing filler, in the rubber composition becomes ideal for improving the physical properties of the resulting crosslinked product (e.g., improved abrasion resistance, improved handling stability, dry grip performance, and wet grip performance). On the other hand, if the number of functional groups of the modified rubber is too large, the interaction between the modified rubbers adsorbed on the reinforcing filler will be too strong, resulting in a reduced effect of dispersing the reinforcing filler, and it is presumed that the effect of the modified copolymer of the present invention in contributing to improving the affinity between the modified rubber and the reinforcing filler will be reduced.

[0123] The average number of functional groups per molecule of the modified vinyl aromatic copolymer is preferably in the range of 2 to 20.

[0124] The amount of the modified compound added in the modified vinyl aromatic copolymer is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, more preferably 1 to 60 parts by mass, even more preferably 1 to 50 parts by mass, and may be 1 to 40 parts by mass, relative to 100 parts by mass of the unmodified polyfunctional vinyl aromatic copolymer. When the amount of the modified compound is more than 200 parts by mass, the dispersibility effect of the reinforcing filler is poor, the processability is deteriorated, and the abrasion resistance of the obtained crosslinked product tends to decrease. When the amount is less than 1 part by mass, the dispersibility effect of the reinforcing filler is poor, and the crosslinked product in which the dispersed state of the reinforcing filler is obtained tends not to be ideal for improving the physical properties. The amount of the modified compound having a functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group added to the modified vinyl aromatic copolymer can be determined using various analytical instruments such as nuclear magnetic resonance spectroscopy.

[0125] The modified vinyl aromatic copolymer of the present invention contains 0.5 to 95.0 mol % of the structural unit (a) derived from a divinyl aromatic compound. When the structural units are composed only of the structural units (a) and (b), the molar fraction of the structural unit (a) is 0.005 to 0.95 relative to the sum of the structural units (a) and (b). This molar fraction is calculated by the following formula (7). (a) / [(a)+(b)] (7) (wherein (a) is the molar fraction of the structural unit (a) derived from a divinyl aromatic compound, and (b) is the molar fraction of the structural unit (b) derived from a monovinyl aromatic compound.) The lower limit of the molar fraction is preferably 0.006, more preferably 0.007, and the upper limit is preferably 0.80, more preferably 0.70. Optimally, it is from 0.01 to 0.60. In the case where structural units other than the structural units (a) and (b) are contained, the lower limit of the content is preferably 0.2 mol%, more preferably 0.4 mol%, and even more preferably 0.6 mol%, and the upper limit is preferably 70 mol%, more preferably 60 mol%, and even more preferably 50 mol%.

[0126] The modified vinyl aromatic copolymer of the present invention contains 5.0 to 99.5 mol % of the structural unit (b) derived from a monovinyl aromatic compound. In terms of molar fraction, it is 0.05 to 0.995. The preferred lower limit is 0.20. The more preferred lower limit is 0.30. The preferred upper limit is 0.994, more preferably 0.993. The most preferred is 0.40 to 0.99.

[0127] When the polymer consists of only the structural units (a), (b) and (c), the molar fraction of the structural unit (b) is calculated by the following formula (8). (b) / [(a)+(b)] (8) (Here, (a) and (b) are defined as the same as in formula (7).) Even in the case where structural units other than the structural units (a) and (b) are contained, the molar fraction of the structural unit (b) is preferably within the above range.

[0128] The structural unit (a) derived from a divinyl aromatic compound contains a vinyl group as a branching component for exhibiting copolymerization reactivity with a conjugated diene compound, while the structural unit (b) derived from a monovinyl aromatic compound does not contain a vinyl group involved in a curing reaction, and thus provides moldability, compatibility, etc. Furthermore, if the molar fraction of the structural unit (a) is less than 0.005, the heat resistance of the cured product is insufficient, and if it exceeds 0.95, the moldability is reduced. Also, if the molar fraction of the structural unit (b) is more than 0.995, the heat resistance is reduced, and if it is less than 0.05, the moldability is reduced.

[0129] The modified vinyl aromatic copolymer of the present invention may contain other structural units in addition to the above structural units, the details of which will be understood from the explanation of the production method.

[0130] 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 500 to 100,000, preferably 600 to 50,000, more preferably 700 to 40,000. It is further preferably 800 to 30,000, and most preferably 900 to 20,000. It is optimally 900 to 10,000. If Mn is less than 300, the amount of functional groups contained in the copolymer is reduced, so that the reactivity with the active end of the conjugated diene copolymer tends to decrease, and if it exceeds 100,000, gel tends to be easily generated, and moldability and tensile elongation at break tend to decrease. The molecular weight distribution is 30.0 or less, preferably 25.0 or less, more preferably 1.3 to 20.0. It is optimally 1.6 to 15.0. If Mw / Mn exceeds 30.0, the processability of the copolymer rubber tends to deteriorate, and gel tends to be generated.

[0131] 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. In order to be a solvent-soluble, polyfunctional copolymer, it is necessary that a part of the vinyl groups of divinylbenzene is left uncrosslinked for functional group modification and has an appropriate degree of branching. Such copolymers or their manufacturing methods are known in the above patent documents. It is preferable that the copolymer dissolves in an amount of 50 g or more in 100 g of solvent. More preferably, the copolymer dissolves in an amount of 80 g or more.

[0132] The modified vinyl aromatic copolymer of the present invention obtained by the above-mentioned production method has at least one reactive functional group selected from amino group, alkoxysilyl group, and hydroxyl group, so it may be molded and cured alone, but it is better to use other polymerizable resins for functional group modification and synthesis of high molecular weight multi-branched components.In particular, the modified vinyl aromatic copolymer of the present invention is used for functional group modification and synthesis of high molecular weight multi-branched components when obtaining a conjugated diene compound alone and / or a conjugated diene compound copolymerized with other monomers to obtain a conjugated diene-based copolymer (rubber).

[0133] Next, the conjugated diene copolymer of the present invention will be described. The modified conjugated diene polymer is obtained by reacting a polymer of a conjugated diene compound (B) having an active end, or a copolymer of a conjugated diene compound (B) having an active end and an aromatic vinyl compound (C) with the modified vinyl aromatic copolymer (A) or (A') of the present invention as a modifier. Hereinafter, the polymer of the conjugated diene compound (B) or the copolymer of a conjugated diene compound (B) having an active end and an aromatic vinyl compound (C) are also collectively referred to as diene polymer. The modified vinyl aromatic copolymer (A) of the first embodiment and the modified vinyl aromatic copolymer (A') of the second embodiment can be used in the same manner, and therefore, hereinafter, both are also referred to as modified vinyl aromatic copolymer (A).

[0134] The modified vinyl aromatic copolymer (A) of the present invention is copolymerized with 1) a conjugated diene compound (B), or 2) a conjugated diene compound (B) and an aromatic vinyl compound (C) as raw materials to obtain a modified conjugated diene copolymer having a branched polymer type modifying group based on the modified vinyl aromatic copolymer of the present invention. When the aromatic vinyl compound (C) is not used, modified diene rubbers such as butadiene rubber and isoprene rubber can be obtained, and modified conjugated diene copolymers such as SBR can be obtained by using the aromatic vinyl compound (C). These modified conjugated diene copolymers exhibit the properties of rubber, so they are also called modified copolymer rubbers.

[0135] The polymerization process for obtaining the modified conjugated diene copolymer of the present invention comprises a polymerization process for obtaining a conjugated diene copolymer having active terminals by polymerizing a conjugated diene compound (B) or copolymerizing the conjugated diene compound (B) and an aromatic vinyl compound (C) using an alkali metal compound or an alkaline earth metal compound as a polymerization initiator, and a terminal modification process for introducing a branched polymer type modifying group based on the modified vinyl aromatic copolymer.

[0136] Examples of the conjugated diene compound (B) include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferred. These may be used alone or in combination of two or more.

[0137] As the aromatic vinyl compound (C), styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, vinylxylene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, tert-butoxydimethylsilylstyrene, isopropoxydimethylsilylstyrene, and the like can be used alone or in combination of two or more kinds, with styrene being particularly preferred.

[0138] When 1,3-butadiene is used as the conjugated diene compound (B) and styrene is used as the aromatic vinyl compound, so-called styrene-butadiene rubber (SBR) is obtained. 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), the result is isoprene rubber (IR). Among them, the styrene-butadiene rubber (SBR) structure is particularly preferred because it has excellent abrasion resistance, heat resistance, and aging resistance.

[0139] [Polymerization process using a polymerization initiator] The alkali metal compound used as the polymerization initiator is not particularly limited, but is preferably, for example, an organolithium compound. The organolithium compound may be any of low molecular weight organolithium compounds and solubilized oligomeric organolithium compounds. Examples of the organolithium compound include a compound having a carbon-lithium bond in the bonding mode between the organic group and lithium, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond. The use of an organolithium compound provides good initiation efficiency and a good living rate of the polymer. The organolithium compound is not particularly limited, but examples of the organolithium compound include an organomonolithium compound, an organodilithium compound, and an organopolylithium compound. As the organic group, a hydrocarbon containing a functional group is suitable, which has the advantage of being excellent in solubility in an organic solvent and also has a good initiation rate. In addition, by using a compound having a nitrogen-lithium bond or a compound having a tin-lithium bond, a modified group containing a functional group can be added to the initiation terminal.

[0140] The organic alkali metal compound other than the organic lithium compound is not particularly limited, but examples thereof include organic sodium compounds, organic potassium compounds, organic rubidium compounds, and organic cesium compounds. More specifically, sodium naphthalene and potassium naphthalene are included. Other examples include alkoxides, sulfonates, carbonates, and amides of lithium, sodium, potassium, and the like. In addition, the organic alkali metal compound may be used in combination with other organic metal compounds. Examples of the alkaline earth metal compound used as a polymerization initiator include an organic magnesium compound, an organic calcium compound, and an organic strontium compound. In addition, compounds such as an alkoxide, a sulfonate, a carbonate, and an amide of an alkaline earth metal may be used. These organic alkaline earth metal compounds may be used in combination with the above-mentioned alkali metal compounds or other organic metal compounds.

[0141] The alkali metal compound having a functional group that can be used as a polymerization initiator is not particularly limited, but includes, for example, a lithium amide compound obtained by lithiating hydrogen of a secondary amine, and an alkyl lithium to which the functional group is bonded. These can provide a functional group to the polymerization initiation terminal of a conjugated diene copolymer. The functional group is not particularly limited, but a functional group that is inactive against alkali metals is preferred, for example, a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, or a protected amino group. In addition, the protected monosubstituted amino group or the protected amino group can be, for example, one hydrogen of a monosubstituted amino group or two hydrogens of an amino group are substituted with a trialkylsilyl group.

[0142] The organolithium compound used as the initiator is not particularly limited, and examples thereof include mono-organolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene. Among these, the mono-organolithium compounds of n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred.

[0143] The polymerization initiator having a functional group is not particularly limited, but specifically includes the compounds shown below. The type of functional group that can be imparted to the polymer is described in parentheses. For example, dipropylamino lithium, diisopropylamino lithium, dibutylamino lithium, tetramethyleneimino lithium, pentamethyleneimino lithium, hexamethyleneimino lithium, heptamethyleneimino lithium, 2-dimethylaminoethyl lithium, 3-dimethylaminopropyl lithium, 3-diethylaminopropyl lithium, 4-dimethylaminobutyl lithium (all of which are disubstituted amino groups), 2-trimethylsilylethylaminoethyl lithium, 3-trimethylsilylmethylaminopropyl lithium (all of which are monosubstituted amino groups), 2-bistrimethylsilylaminoethyl lithium, and 3-bistrimethylsilylaminopropyl lithium (all of which are amino groups).

[0144] As the polymerization initiator, an oligomer initiator in which various lithium-based initiators react with a monomer can be used. In this case, a monomer having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group can be used. The oligomer initiator is not particularly limited, but a molecular weight of 1000 or less is preferable because it is easy to handle industrially. Polymerization or copolymerization is performed using a polymerization initiator having a functional group, and in the next step, a branched polymer-type modifying group derived from the modified vinyl aromatic copolymer of the present invention can be introduced into the terminal end.

[0145] Furthermore, the polymerization step in the case of using a polyfunctional initiator is a step of polymerizing a conjugated diene compound (B) using the polyfunctional initiator, or copolymerizing the conjugated diene compound (B) and an aromatic vinyl compound (C) to obtain a conjugated diene copolymer having an active end. Thereafter, as a method for introducing functional groups into two or more terminals of a conjugated diene copolymer having active terminals, a terminal modification step is carried out in which a modified vinyl aromatic copolymer is reacted with two or more active terminals of the conjugated diene copolymer to introduce two or more branched polymer type modifying groups (A) based on the modified vinyl aromatic copolymer.

[0146] (Multifunctional initiator) The polyfunctional initiator is not particularly limited, but specifically includes an organic dilithium compound and an organic polylithium compound. The organic group is not particularly limited, but a hydrocarbon is preferable. This has the advantage of excellent solubility in organic solvents and also excellent initiation speed. In addition, the preparation method of the polyfunctional initiator is not particularly limited, but specifically includes a method of reacting a dispersion of metallic lithium with a polyhalogenated hydrocarbon compound, a method of reacting metallic lithium with a diene compound, and a method of reacting an organic monolithium compound with a polyfunctional compound. Among these, a method of reacting an organic monolithium compound with a polyfunctional compound is preferable. The polyfunctional compound is not particularly limited, but specifically includes an aromatic compound having a plurality of double bonds adjacent to an aromatic group, and a compound having a plurality of active hydrogens that can be substituted for lithium. When reacting an organic monolithium compound with these polyfunctional compounds, it is also possible to make an oligomer by making a conjugated diene compound or an aromatic vinyl compound present. In addition, in order to increase the reactivity of the organic monolithium compound, a polar compound such as an ether compound or a tertiary amine compound may be present. The aromatic compound having a plurality of double bonds adjacent to an aromatic group is not particularly limited, but examples thereof include diisopropenylbenzene, divinylbenzene, and the like. The compound having a plurality of active hydrogens that can be substituted for lithium is not particularly limited, but an example thereof is 1,3,5-trimethylbenzene.

[0147] The hydrocarbon dilithium compound is not particularly limited, but examples thereof include 1,3-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,4-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,3-bis(1-lithio-1,3,3-trimethylbutyl)benzene, and 1,4-bis(1-lithio-1,3,3-trimethylbutyl)benzene, which are obtained by reacting secondary or tertiary butyllithium with diisopropenylbenzene. In addition, the above-mentioned hydrocarbon polylithium compound is not particularly limited, but examples thereof include a reaction product of n-butyllithium, divinylbenzene and 1,3-butadiene, and a reaction product of secondary or tertiary butyllithium and 1,3,5-trimethylbenzene. The amount of these polyfunctional initiators used is adjusted depending on the molecular weight of the target butadiene-based polymer, and can be 0.01 to 0.2 parts by mass relative to 100 parts by mass of the monomer. It is preferably 0.02 to 0.15 parts by mass. In this case, it is preferable to take into consideration deactivation due to moisture and impurities in the monomer and solvent, chain transfer due to impurities, deactivation due to the generation of metal hydride at the polymerization terminal, etc.

[0148] When producing a conjugated diene copolymer, a polar compound may be added. By adding a polar compound, a vinyl aromatic compound can be randomly copolymerized with a conjugated diene compound such as 1,3-butadiene. The polar compound can also be used as a vinylizing agent for controlling the microstructure of the conjugated diene portion. It is also effective in promoting the polymerization reaction. Examples of polar compounds include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium tert-amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more. The amount of polar compound used is not particularly limited and can be selected according to the purpose. Usually, it is preferably 0.01 to 100 moles per mole of polymerization initiator or polyfunctional initiator. Such polar compounds can be used as a regulator of the microstructure of the polymer conjugated diene portion according to the desired vinyl bond amount in an appropriate amount. Many polar compounds simultaneously have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and can be used as an agent for adjusting the distribution of the aromatic vinyl compound or the amount of styrene blocks. As a method for randomizing a conjugated diene compound and an aromatic vinyl compound, for example, as described in JP-A-59-140211, a method may be used in which a copolymerization reaction is started with the entire amount of styrene and a part of the conjugated diene compound (B), and the remaining conjugated diene compound (B) is added continuously or intermittently during the copolymerization reaction.

[0149] 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, a hydrocarbon-based solvent such as a saturated hydrocarbon or an aromatic hydrocarbon is used. Specific examples of the solvent include 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-based solvents consisting of mixtures thereof. The above-mentioned conjugated diene compound and polymerization solvent are preferably treated with an organometallic compound, either alone or in the form of a mixture thereof. This allows the allenes and acetylenes contained in the conjugated diene compound and polymerization solvent to be treated. As a result, a polymer having a high concentration of active terminals can be obtained, and a high modification rate can be achieved.

[0150] The polymerization temperature when the conjugated diene compound (B) or the conjugated diene compound (B) and the aromatic vinyl compound (C) are copolymerized is not particularly limited as long as it is a temperature at which living anionic polymerization proceeds, but from the viewpoint of productivity, it is preferably 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 functional group represented by the formula (2) and / or formula (3) of the present invention with the active terminal after the polymerization is completed, it is preferably 120°C or lower, and more preferably 50 to 100°C. The polymerization mode when the conjugated diene compound (B) or the conjugated diene compound (B) and the aromatic vinyl compound (C) are copolymerized is not particularly limited, and can be a batch polymerization mode (also called a "batch polymerization mode"), a continuous polymerization mode, or the like. In the continuous polymerization mode, one or more connected reactors can be used. The reactors used are tank-type reactors or tubular reactors equipped with an agitator. In the batch polymerization mode, the molecular weight distribution of the obtained polymer is generally narrow, and Mw / Mn tends to be 1.0 or more and less than 1.8. In the continuous polymerization mode, the molecular weight distribution is generally wide, and Mw / Mn tends to be 1.8 or more and less than 3.

[0151] [Terminal modification step] The terminal modification step is a step of reacting the modified vinyl aromatic copolymer of the present invention with the active terminal of the conjugated diene copolymer to introduce the functional group and synthesize a multi-branched high molecular weight material. This step is the same whether a polymerization initiator is used or a multifunctional initiator is used. The reaction temperature, reaction time, etc., when reacting the modified vinyl aromatic copolymer with the polymer active terminal are not particularly limited, but it is preferable to react at 0 to 120 ° C. for 30 seconds or more. The amount of the modified vinyl aromatic copolymer to be added is not particularly limited, but the total number of moles of the modified vinyl aromatic copolymer (A) is preferably in the range of 0.01 to 6 times, more preferably in the range of 0.02 to 3 times, and even more preferably in the range of 0.05 to 2 times, relative to the number of moles of the polymerization initiator or polyfunctional initiator, i.e., the number of polymer molecules. If the amount of addition is 0.05 times or more, it is preferable from the viewpoint of obtaining a sufficient modification rate in the target modified conjugated diene polymer. In addition, the branching degree and the amount of production of the branched polymer component in which the polymer terminals are coupled to each other can be controlled arbitrarily by the structure of the modified vinyl aromatic copolymer (A), in which case, a modified vinyl aromatic copolymer (A) with a high functionality can be used as the modified vinyl aromatic copolymer (A). The amount of such modified vinyl aromatic copolymer (A) added is preferably 0.7 or less times, in terms of functional group equivalent, the number of moles of the polymerization initiator or polyfunctional initiator, that is, the number of polymer molecules.

[0152] In the case where the polymerization process is a batch process, the terminal modification process may be carried out in the reactor used in the polymerization process, or may be carried out in a subsequent reactor. In the case where the polymerization process is a continuous process, the terminal modification process is carried out in a subsequent reactor. The terminal modification process is preferably carried out immediately following the polymerization process, and the modifying agent is mixed and the reaction is carried out preferably within 5 minutes. The reactor for the modification reaction is preferably one that can perform sufficient stirring. Specifically, there are a static mixer type reactor, a stirrer-equipped tank type reactor, and the like. In addition, in order to prevent side reactions in which functional groups of the modified vinyl aromatic copolymer bond with each other, or to improve affinity with different types of fillers, one or more functional groups different from those of the modified vinyl aromatic copolymer can be introduced to the active end of the conjugated diene copolymer.

[0153] When introducing a functional group different from that of the modified vinyl aromatic copolymer into the active end of the conjugated diene copolymer, the active end of the conjugated diene copolymer is reacted with a modifying compound having at least one functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group to form a bond, or is reacted with a compound that forms these functional groups to modify the end end. In the modifying compound used in this case, the functional group that is bonded to the active end of the conjugated diene polymer is not particularly limited, but specific examples include a halogen group, a double bond, a ketone group, an ester group, an amide group, an epoxy group, and an alkoxysilyl group.

[0154] (Modified Compounds) The terminal modification step is a step of reacting a modifying compound having at least one functional group selected from an amino group, an alkoxysilyl group, and a hydroxyl group with the active terminal of the butadiene copolymer to form a bond, or reacting a compound that forms these functional groups to modify the terminal terminal. In the modifying compound used in this step, the functional group that bonds with the active terminal of the conjugated diene polymer is not particularly limited, but specific examples include a halogen group, a double bond, a ketone group, an ester group, an amide group, an epoxy group, and an alkoxysilyl group.

[0155] Among the modified compounds, the compound having an amino group is not particularly limited, but specifically includes a compound having an amino group and a functional group that bonds with the active terminal of a polymer in the molecule, and preferably does not have active hydrogen.The amino group is not particularly limited, but specifically, a functional group that is inactive to alkali metals is preferred, and a disubstituted amino group, that is, a tertiary amine, a protected monosubstituted amino group, and an amino group with two hydrogens protected are preferred.In addition, examples of a protected monosubstituted amino group or an amino group with two hydrogens protected include those in which one hydrogen of a monosubstituted amino group or two hydrogens of an amino group are respectively substituted with a trialkylsilyl group.

[0156] Among the modifiers, the compound having an alkoxysilyl group is not particularly limited, but specifically includes a compound having multiple alkoxysilyl groups in the molecule (including a compound having a silyl group to which multiple alkoxy groups are bonded), and a compound having an alkoxysilyl group in the molecule and a functional group that bonds with the active end of the polymer.It is preferable that these are compounds that do not have active hydrogen. Among the modifying agents, the compound that forms a hydroxyl group is not particularly limited, but specific examples include a compound having a functional group that bonds with the active terminal of the polymer and generates a hydroxyl group after a bonding reaction, and a compound having a functional group that does not bond with the active terminal of the polymer and generates a hydroxyl group later by a reaction such as hydrolysis, and it is preferable that the compound does not have active hydrogen.

[0157] Examples of the compound having a functional group that generates a hydroxyl group after the above-mentioned bonding 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 bonding reaction include compounds having an alkoxysilyl group, an aminosilyl group, etc.

[0158] Specific examples of the modifying compound are shown below. The compound that bonds with the active terminal of the polymer to form an amino group at the terminal of the polymer is not particularly limited, but examples thereof include C=N double bond compounds such as N,N'-dicyclohexylcarbodiimide. The compound that bonds with the active terminal of a polymer to form an amino group and a hydroxyl group at the terminal 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) and N,N,N',N'-tetraethyl-4,4'-diaminobenzophenone; cyclic urea compounds, such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; cyclic amides, i.e., lactam compounds; amino group-containing epoxy compounds, such as N,N,N',N'-tetraglycidyl-1,3-bisaminomethylcyclohexane; and epoxy compounds having a nitrogen-containing heterocyclic group as described in JP-A 2001-131227. The compound that bonds with the active terminal of a polymer to form an alkoxysilyl group at the terminal of the polymer is not particularly limited, but examples thereof include halogenated alkoxysilane compounds such as trimethoxychlorosilane, triethoxychlorosilane, and diphenoxydicrylosilane; and polyfunctional alkoxysilane compounds such as bis(trimethoxysilyl)ethane and bis(3-triethoxysilylpropyl)ethane. The compound that bonds with the active terminal of the polymer to form an alkoxysilyl group and a hydroxyl group at the terminal of the polymer is not particularly limited, but examples thereof include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and polysiloxane compounds having an epoxy group and an alkoxysilyl group in the molecule.

[0159] The compound that bonds with the active terminal of the polymer to form an amino group and an alkoxysilyl group at the terminal of the polymer is not particularly limited, and examples thereof include alkoxysilane compounds to which an alkyl group having an amino substituent is bonded, such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminopropyltriethoxysilane, bis(3-trimethoxysilylpropyl)methylamine, and bis(3-triethoxysilylpropyl)methylamine; alkoxysilane compounds having a protected mono-substituted amino group bonded thereto, such as N-[2-(trimethoxysilanyl)-ethyl]-N,N',N'-trimethylethane-1,2-diamine, 1-[3-(triethoxysilyl)-propyl]-4-methylsilyl-ethane-1,2-diamine, 3-(4-trimethylsilyl-1-piperazinyl)propyltriethoxysilane, etc., as described in WO2007 / 034785A; alkoxysilane compounds having a plurality of substituted amino groups bonded thereto, as described in WO2008 / 013090, such as 2-(trimethoxysilanyl)-1,3-dimethylimidazolidine and 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 and 1,4-bis[3-(triethoxysilyl)propyl]piperazine; Examples include alkoxysilane compounds having an azasilane group bonded thereto, such as -[N,N-bis(trimethylsilyl)amino]propyltrimethoxysilane, 3-[N,N-bis(trimethylsilyl)amino]propylmethyldiethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, and 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, which are described in WO2011 / 129425. The compound that bonds with the active terminal of the polymer to form a hydroxyl group at the terminal of the polymer is not particularly limited, but examples thereof include epoxy compounds such as ethylene oxide and propylene oxide; and ketone compounds such as benzophenone.

[0160] [Main Chain Modification Step] The main chain modification step is a step of modifying the main chain by hydrosilylation reaction between the vinyl group of the main chain of the modified conjugated diene polymer having the modified terminal and a silicon 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 silicon compound forming at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group. This step is the same whether a polymerization initiator is used or the polyfunctional initiator is used. The hydrosilylation reaction can be carried out in a kneader in an organic solvent solution or as a polymer (without a solvent). Specifically, a silicon compound such as a hydrosilane compound having the functional group can be reacted in the presence of a catalyst to modify the vinyl group of the main chain of the conjugated diene copolymer. After the polymerization step in solution polymerization, it is preferable to use the polymer solution in which the terminals of the polymer have been modified as described above.

[0161] The silicon compound is not particularly limited, and specifically includes a hydrosilane compound. Such a hydrosilane compound is not particularly limited, and specifically includes any hydrosilane compound having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group. Among them, preferred is a hydrosilane compound represented by the general formula HSiR'' 3-n X n (R" is not particularly limited, but represents a hydrocarbon group having 1 to 20 carbon atoms, X represents an amino group, an alkoxy group, a hydroxyl group or a hydrocarbon or organosilane compound group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, and n is an integer of 1 to 3). More preferably, n is 1, and R" preferably represents a hydrocarbon having 1 to 3 carbon atoms. When the hydrosilane compound has such a structure, the yield of the hydrosilylation reaction is high. The silicon compound may be a silicon compound that forms the above-mentioned functional group by hydrolysis or the like after the hydrosilanization reaction. Such silicon compounds are not particularly limited, and specific examples thereof include hydrosilane compounds having a functional group that forms at least one functional group of an amino group, an alkoxysilyl group, or a hydroxyl group by hydrolysis or the like. More specific examples thereof include hydrosilane compounds having a protected mono-substituted amino group, a protected di-substituted amino group, a protected hydroxyl group, or the like.

[0162] The silicon compound having an alkoxy group is not particularly limited, but specific examples include organosiloxane compounds having an H-Si group and an alkoxysilyl group in the molecule, such as dimethylmonomethoxysilane, dimethylmonoethoxysilane, dimethylmonopropoxysilane, dimethylmonobutoxysilane, methyldimethoxysilane, methyldiethoxysilane, methyldipropoxysilane, ethyldiethoxysilane, trimethoxysilane, and triethoxysilane. The silicon compound having a disubstituted amino group is not particularly limited, but specific examples thereof include dimethylaminodimethylsilane, diethylaminodimethylsilane, diethylaminodiethylsilane, 3-diethylaminopropyldimethylsilane, 4-dimethylaminobutyldimethylsilane, and 6-diethylaminohexyldimethylsilane. The silicon compound having a protected monosubstituted amino group is not particularly limited, but specific examples include N-methyl-N-trimethylsilylaminodimethylsilane and N-ethyl-N-trimethylsilylaminodiethylsilane.

[0163] The silicon compound having a protected disubstituted amino group is not particularly limited, but specific examples include N,N-bistrimethylsilylaminodimethylsilane and N,N-bistrimethylsilylaminodiethylsilane.

[0164] The silicon compound having a hydroxyl group is not particularly limited, but specific examples include dimethylhydroxysilane, diethylhydroxysilane, and dibutylhydroxysilane.

[0165] The silicon compound that forms a hydroxyl group upon hydrolysis is not particularly limited, but specific examples include alkoxysilane compounds such as dimethylmonomethoxysilane, dimethylmonoethoxysilane, methyldimethoxysilane, trimethoxysilane, and triethoxysilane; and silane compounds having an epoxy group such as dimethylglycidylsilane and diethylglycidylsilane.

[0166] When modifying the vinyl group of the main chain of the modified conjugated diene copolymer, the amount of the hydrosilane compound to be reacted is arbitrary depending on the purpose, but is preferably 1 to 10 moles per mole of the main chain of the copolymer. By modifying 1 to 10 moles per mole of the main chain, as described below, when the modified diene copolymer and silica are mixed to obtain a rubber composition, good affinity is obtained and the rubber composition has excellent processability. More preferably, it is 2 to 5 moles per mole of the main chain.

[0167] A specific catalyst may be used when carrying out the hydrosilylation reaction. The catalyst is not particularly limited, but for example, platinum or a platinum-containing catalyst is mainly used. Preferably, a homogeneous platinum catalyst is suitably used, such as a chloroplatinic acid solution (i.e., Speier catalyst), a Pt2(divinyltetramethyldisiloxane)3 solution (i.e., Karstedt catalyst), or dichloro(η4-cyclo-1,5-diene)Pt(II). The amount of the platinum catalyst used in the reaction is preferably 0.01 to 10 mmol / mol, more preferably 0.1 to 1 mmol / mol, per hydrosilane compound.

[0168] Other examples of catalysts that can be used in the hydrosilylation reaction include metallocene compounds containing any of Ti, Zr, Hf, Ni, Co, Ru, and Rh. In particular, reaction products of titanocene compounds with organolithium or organoaluminum are preferred.

[0169] The hydrosilylation reaction is preferably carried out in the range of 20 to 150°C, more preferably in the range of 50 to 120°C. Within this range, the reaction can be carried out in an appropriate reaction time, and side reactions such as gelation occur less frequently, making it practical. When the polymerization solution is used as is and the hydrosilylation reaction is carried out following the terminal modification reaction, the reaction can be carried out at the same temperature as the polymerization temperature. In the solution state, the reaction time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 2 hours.

[0170] The weight-average molecular weight (polystyrene equivalent) of the modified conjugated diene copolymer of the present invention is preferably 100,000 to 2,000,000, taking into consideration processability and physical properties, and more preferably 150,000 to 1,000,000. The weight-average molecular weight can be determined by measuring a chromatogram using GPC with a column filled with polystyrene gel, and using a calibration curve using standard polystyrene.

[0171] Regarding the composition of the structural units of the modified conjugated diene copolymer of the present invention, when the aromatic vinyl compound (C) is not used, it is preferable that the ratio of the polyfunctional vinyl aromatic copolymer (A) to the conjugated diene compound (B) is within the following range. The structural unit (A1) derived from the modified vinyl aromatic copolymer (A) having the structural unit (c) composed of the silane functional group represented by the formula (2) and / or formula (3) is 0.001 to 6% by weight, preferably 0.001 to 5% by weight, more preferably 0.005 to 5% by weight, even 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 even more preferably 95 to 99.99% by weight.

[0172] When an aromatic vinyl compound (C) is used, the above proportions are preferably within the following ranges: the structural unit (A1) is within the same range as above, the structural unit (B1) is 30 to 97.999% by weight, preferably 45 to 94.995% by weight, and 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 more preferably 10 to 40% by weight.

[0173] In addition, the microstructure (cis, trans, vinyl bond amount) of the modified conjugated diene copolymer can be arbitrarily changed by using a polar compound, etc., but the content of vinyl bonds (1,2-bonds) in the conjugated diene unit before the end is modified is preferably 10 to 80 mol%. When the modified conjugated diene copolymer of the present invention is made into a rubber composition described later and further crosslinked to be used as an automobile tire, in order to highly balance the rolling resistance performance and the wear resistance, the content is preferably 20 to 75 mol%, more preferably 30 to 75 mol%, and even more preferably 40 to 70 mol%. At this time, the mass ratio of cis bonds and trans bonds in the conjugated diene bond unit is preferably cis bonds / trans bonds=1 / 1.1 to 1.5.

[0174] If necessary, a reaction terminator may be added to the polymer solution of the modified conjugated diene copolymer obtained by the above-mentioned polymerization method. Examples of the reaction terminator include alcohols such as methanol, ethanol, and propanol; organic acids such as stearic acid, lauric acid, and octanoic acid; and water.

[0175] After the polymerization reaction of the modified conjugated diene copolymer, the metals contained in the polymer may be deashed as necessary. For example, the deashing method may involve contacting the polymer solution with water, an organic acid, an inorganic acid, an oxidizing agent such as hydrogen peroxide, etc. to extract the metals, and then separating the aqueous layer.

[0176] [Post-processing] When the modified conjugated diene polymer having terminal modification and main chain modification as described above is obtained as a solution, an antioxidant and additives may be added as necessary, and then the solvent may be removed and the polymer may be dried in a normal manner. This allows the polymer to be used as a raw material for the rubber composition described below. Specifically, the method includes a method using steam stripping and dehydration drying, a direct stripping method using a drum dryer, flashing, and a vent extruder.

[0177] The antioxidant is not particularly limited, and known ones can be used. Examples of the antioxidant include phenol-based stabilizers, phosphorus-based stabilizers, and sulfur-based stabilizers. Specific examples include 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

[0178] If necessary, additives such as water, alcohols such as methanol, ethanol, isopropanol, etc., carboxylic acids such as stearic acid, oleic acid, myristic acid, lauric acid, decanoic acid, citric acid, malic acid, etc., aqueous inorganic acids, carbon dioxide gas, etc. may be added in order to remove or neutralize ionic substances.

[0179] In the modified conjugated diene copolymer of the present invention, when the total area is taken as 100% in a differential molecular weight distribution curve obtained by GPC measurement, the area of ​​a region having a number average molecular weight (Mn) three times or more of the lowest molecular weight peak is preferably 10% or more. This will be explained with reference to FIG. Figure 1 shows a typical example of a GPC elution curve, and the positions of the peak top Mp and the molecular weight 3Mp, which is three times the peak top. The area of ​​the region of the lowest molecular weight peak with a number average molecular weight of 3Mp (the region to the right of 3Mp in Figure 1) which is three times the number average molecular weight Mp, should be 10% or more by area. This means that there is a relatively large amount of high molecular weight components.

[0180] The modified vinyl aromatic copolymer (A) of the present invention can be used for modifying rubber compositions by itself. By compounding this copolymer (A) in a rubber composition, the processability of the rubber composition is improved, and the affinity of the reinforcing filler in the obtained rubber composition is improved, so that it is likely to exist in the vicinity of the reinforcing filler when preparing the rubber composition, and as a result, it is estimated that it is ideal for improving the physical properties (e.g., dry grip performance, wet grip performance) of the crosslinked product in which the reinforcing filler and the like in the rubber composition are dispersed. In addition, the branched polymer type modifying group based on the modified vinyl aromatic copolymer is likely to exist in the vicinity of the reinforcing filler, so that a crosslinked product with excellent abrasion resistance can be obtained.

[0181] Next, the modified conjugated diene copolymer composition (hereinafter also referred to as rubber composition) of the present invention will be described. The rubber composition contains the modified conjugated diene polymer and a filler. In another embodiment of the rubber composition of the present invention, the rubber composition contains 0.5 to 200 parts by mass of a reinforcing filler based on 100 parts by mass of the modified conjugated diene-based polymer. Another embodiment of the rubber composition of the present invention contains 100 parts by mass of raw rubber containing 20 parts by mass or more of the modified conjugated diene polymer, and 5 to 200 parts by mass of a filler.

[0182] [Raw rubber] The content of the modified conjugated diene polymer in 100 parts by mass of raw rubber is 20 parts by mass or more, preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more. When it is 20 parts by mass or more, the dispersibility aimed at by the present invention is excellent, and when the rubber composition of the present embodiment is used as a vulcanized composition, the performance such as tensile property and viscoelastic property is excellent, and when it is used as a material for tires, excellent fuel efficiency performance, grip performance, abrasion resistance, and rigidity are obtained. In addition, the content of the modified conjugated diene polymer is preferably 90 parts by mass or less, more preferably 80 parts by mass or less. By making it 90 parts by mass or less, the Mooney viscosity of the unvulcanized modified conjugated diene copolymer composition of the present invention is lowered and the processability is improved.

[0183] The raw rubber other than the modified butadiene polymer is not particularly limited, and examples thereof include a conjugated diene polymer or a hydrogenated product thereof, a random copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof, a block copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof, other conjugated diene copolymers or a hydrogenated product thereof, a non-diene polymer, natural rubber, and the like.

[0184] Specific examples of the conjugated diene polymer or its hydrogenated product are not particularly limited, and include, for example, butadiene rubber or its hydrogenated product, isoprene rubber or its hydrogenated product, and the like.

[0185] Specific examples of the random copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof include, but are not limited to, styrene-butadiene copolymer rubber or a hydrogenated product thereof.

[0186] Specific examples of the block copolymer of a conjugated diene compound and a vinyl aromatic compound or a hydrogenated product thereof include, but are not limited to, styrene-based elastomers such as a styrene-butadiene block copolymer or a hydrogenated product thereof, and a styrene-isoprene block copolymer or a hydrogenated product thereof.

[0187] Specific examples of other conjugated diene copolymers or hydrogenated products thereof are not particularly limited, and include, for example, acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0188] Furthermore, the non-diene polymer is not particularly limited, and examples thereof include olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0189] In the present invention, when the modified conjugated diene polymer is a modified styrene-butadiene rubber, the other rubber is preferably polybutadiene, and when the modified butadiene polymer is a modified polybutadiene, the other rubber is preferably natural rubber or polyisoprene rubber.

[0190] The weight average molecular weight of the above-mentioned various rubber-like polymers is preferably 2,000 to 2,000,000, more preferably 5,000 to 1,500,000, from the viewpoint of the balance between performance and processing characteristics. Also, so-called liquid rubbers with low molecular weights can be used. These rubber-like polymers may be used alone or in combination of two or more. The weight average molecular weight here is the weight average molecular weight (Mw) calculated in terms of polystyrene obtained by gel permeation chromatography (GPC) measurement.

[0191] The amount of filler used relative to the raw rubber is adjusted so that the hardness and modulus increase as the filler is used in large amounts, and the desired physical properties are obtained depending on the application. Within this range, the filler is well dispersed and has good processability. For tire applications, the filler is preferably 5 to 150 parts by mass, and for footwear applications, the filler is preferably 30 to 200 parts by mass. Within the range of this embodiment, it is possible to widely handle a wide range of applications from soft to hard.

[0192] [Reinforcing filler] In another embodiment of the rubber composition of the present invention, the modified conjugated diene polymer is preferably mixed with the raw rubber in an amount of 0.5 to 200 parts by mass of at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, per 100 parts by mass of the modified conjugated diene polymer, preferably per 100 parts by mass of the raw rubber.

[0193] As the silica-based inorganic filler contained in the rubber composition, it is preferable to use solid particles whose main constituent unit is SiO2 or silicate. Here, the main component means a component that occupies 50% by mass or more of the total, preferably a component that occupies 70% by mass or more, and more preferably a component that occupies 90% by mass or more.

[0194] Specific examples of silica-based inorganic fillers include inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. The silica-based inorganic fillers may be used alone or in combination of two or more. In addition, silica-based inorganic fillers with hydrophobic surfaces and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based inorganic fillers may also be used. Among these, silica and glass fiber are preferred, and silica is more preferred.

[0195] As the silica, dry silica, wet silica, synthetic silicate silica, etc. can be used. Among them, wet silica is preferred because it is superior in both improving the fracture properties and wet skid resistance performance.

[0196] In the rubber composition of the present invention, other reinforcing fillers can be used in combination. Due to the combined effect of various functional groups of the modified conjugated diene copolymer of the present invention, the dispersion of both silica and other reinforcing fillers is improved, and an excellent reinforcing effect can be obtained.

[0197] The silica used as the reinforcing filler has a BET specific surface area of ​​50 to 500 m 2 By blending such silica, excellent fuel economy, abrasion resistance, wet skid performance and handling stability are obtained.

[0198] In the rubber composition of the present invention, the dispersibility of silica is good, so that even silica having a high specific surface area, that is, silica with a fine particle size, can be dispersed well.

[0199] The silica-based inorganic filler can be fine-grained silica, and the fine-grained silica has a CTAB specific surface area of ​​180 m 2 / g or more, BET specific surface area is 185m 2 By compounding such fine particle silica, a rubber composition having excellent fuel economy, abrasion resistance, wet skid performance and handling stability can be obtained.

[0200] The CTAB (cetyltrimethylammonium bromide) specific surface area of ​​the fine particle silica is not particularly limited, and is preferably 190 m 2 / g or more, more preferably 195m 2 / g or more, more preferably 197m 2 / g or more. CTAB specific surface area is 180m 2 When the specific surface area is 500 m / g or more, a rubber composition having excellent abrasion resistance can be obtained. 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. CTAB specific surface area is 500m 2 When the CTAB specific surface area is 190 to 300 m / g or less, a rubber composition having excellent processability can be obtained. 2 The CTAB specific surface area is measured in accordance with ASTM D3765-92.

[0201] The BET specific surface area of ​​the fine particle silica is not particularly limited, and is preferably 190 m 2 / g or more, more preferably 195m 2 / g or more, more preferably 210m 2 / g or more. BET specific surface area is 185m 2 When the BET specific surface area is 500 m / g or more, a rubber composition having excellent abrasion resistance can be obtained. 2 / g or less, more preferably 300m 2 / g or less, more preferably 260m 2 / g or less. BET specific surface area is 500m 2When the specific surface area of ​​silica is 0.1 to 1.0 μm / g or less, a modified conjugated diene copolymer composition having excellent processability can be obtained. The BET specific surface area of ​​silica is measured in accordance with ASTM D3037-81.

[0202] The aggregate size of the fine silica is not particularly limited, and can be 30 nm or more, preferably 35 nm or more, more preferably 40 nm or more, even more preferably 45 nm or more, even more preferably 50 nm or more, and even more preferably 55 nm or more. The aggregate size is not particularly limited, and is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 70 nm or less, and particularly preferably 65 nm or less. By having such an aggregate size, it is possible to provide excellent reinforcement, low fuel consumption, abrasion resistance, wet skid performance, and steering stability while having good dispersibility. The aggregate size is also called the aggregate size or the maximum frequency Stokes equivalent diameter, and corresponds to the particle size when a silica aggregate composed of a plurality of primary particles connected together is considered as one particle. The aggregate size can be measured, for example, using a disk centrifugal 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 2011-132307 A.

[0203] The average primary particle size of the fine silica is not particularly limited, and is preferably 25 nm or less, more preferably 22 nm or less, even more preferably 17 nm or less, and particularly preferably 14 nm or less. The lower limit of the average primary particle size is not particularly limited, but is preferably 3 nm or more, more preferably 5 nm or more, and even more preferably 7 nm or more. In this range, the dispersion property and reinforcement are excellent. The average primary particle size of the fine silica can be obtained by observing with a transmission or scanning electron microscope, measuring 400 or more primary particles of silica observed in the field of view, and averaging the results.

[0204] The amount of the fine silica in the rubber composition of the present invention is not particularly limited, and is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, based on 100 parts by mass of the rubber component. If it is 5 parts by mass or more, the effect of blending the fine silica can be sufficiently obtained. The upper limit of the amount of the fine silica is 200 parts by mass or less, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less. If it is 200 parts by mass or less, substantially good processability can be obtained.

[0205] The rubber composition of the present invention preferably further contains a reinforcing filler having a BET specific surface area of ​​185 m 2 It is preferable that the silica or carbon black contained is less than 5 to 100 parts by mass / g.

[0206] In addition, it is used as a reinforcing filler with a BET nitrogen adsorption specific surface area (N2SA) of 185m 2 Silica of less than 150 m / g is preferably used, and more preferably less than 150 m 2 / g of silica is used, preferably 50m 2 In this range, a good balance between reinforcing properties and dispersibility is achieved. Also, a particle size suitable for the application is used.

[0207] Carbon black is classified according to the ASTM classification of rubber carbon black, and is selected according to the application, from N110, N220, N330, N339, N550, N660, etc. By using carbon black in combination, it is possible to increase the reinforcing properties, and when used in tire tread applications, it is possible to improve the dry grip performance. The carbon black preferably has a BET nitrogen adsorption specific surface area (N2SA) of 185 m 2 / g is preferably less than 30m 2 / g or more, more preferably 50 to 130m 2 / g range. In this range, the balance between reinforcing properties and dispersibility is good. When used for tire tread applications, N220, N330, and N339 are more preferable.

[0208] As the reinforcing filler, in addition to the above-mentioned silica, other reinforcing fillers can be used. The other reinforcing fillers are not particularly limited, but the metal oxide as the reinforcing filler is preferably a solid particle mainly composed of a component having a chemical formula MxOy (M represents a metal atom, and x and y each represent an integer of 1 to 6). Here, the main component means a component that occupies 50% by mass or more of the total, preferably a component that occupies 70% by mass or more, and more preferably a component that occupies 90% by mass or more. As the metal oxide, for example, alumina, titanium oxide, magnesium oxide, zinc oxide, etc. can be used.

[0209] Examples of metal hydroxides as reinforcing fillers include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0210] The metal oxides and metal hydroxides as the other reinforcing fillers may be used alone or in combination of two or more kinds, and may also be used in mixture with other inorganic fillers.

[0211] In addition, a silane coupling agent may be used in the rubber composition of the present invention. The silane coupling agent is not particularly limited, but may be, for example, a compound having both a silica affinity portion and a polymer affinity portion in the molecule, such as a sulfide-based compound, a mercapto-based compound, a vinyl-based compound, an amino-based compound, a glycidoxy-based compound, a nitro-based compound, or a chloro-based compound.

[0212] Examples of sulfide compounds include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylsilyl. thiocarbamoyl 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.

[0213] Examples of the mercapto-based compound include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane. Examples of the vinyl-based compound include vinyltriethoxysilane and vinyltrimethoxysilane. Examples of the amino compound include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.

[0214] Examples of the glycidoxy compounds include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. Examples of the nitro-based compound include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.

[0215] Examples of the chloro-based compounds include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane. Examples of other compounds include octyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0216] 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, silane coupling agents containing sulfur such as sulfide compounds and mercapto compounds are preferred, and bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide, and 3-mercaptopropyltrimethoxysilane are more preferred.

[0217] The amount of the silane coupling agent is 1 to 20 parts by mass, preferably 2 to 15 parts by mass, per 100 parts by mass of silica. When the silane coupling agent is blended in this range, the dispersibility of the silica is further improved, the processability is improved, and further, the performance of the vulcanized rubber is improved, such as the abrasion resistance.

[0218] In addition, in the rubber composition of the present invention, the hardness and modulus can be adjusted by using a plasticizer. The plasticizer is not particularly limited, but for example, the same oil as the above-mentioned extender oil can be used, and in addition, various natural oils, synthetic oils, low molecular weight polymers, etc. can be used. Also, known processing aids can be used.

[0219] (Crosslinking agent) The rubber composition of the present invention may be further subjected to a crosslinking treatment by adding a crosslinking agent, compounding agents, etc. Such a crosslinking agent is not particularly limited, but for example, a sulfur-based vulcanizing agent, an organic peroxide, etc. may be used.

[0220] The sulfur-based vulcanizing agent is not particularly limited, but for example, sulfur, morpholine disulfide, etc. are used, and the organic peroxide is, for example, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, cumene hydroperoxide, etc. are used.

[0221] Furthermore, a vulcanization accelerator may be blended as necessary. The vulcanization accelerator is not particularly limited, but may contain 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.

[0222] Furthermore, a vulcanization aid may be blended as necessary, and the vulcanization aid is not particularly limited, but for example, zinc oxide, stearic acid, etc. can be used. Furthermore, an anti-aging agent can be used.

[0223] The modified conjugated diene copolymer composition of the present invention can be produced by mixing the above-mentioned components.

[0224] The method of mixing the modified conjugated diene copolymer with at least one reinforcing filler selected from the group consisting of silica-based inorganic fillers, metal oxides, metal hydroxides, and carbon black, and optionally with a silane coupling agent, is not particularly limited. For example, a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method of dissolving and mixing each component and then removing the solvent by heating, etc., can be mentioned. Among these, the melt-kneading method using a roll, a Banbury mixer, a kneader, or an extruder is preferred from the viewpoint of productivity and good kneading. In addition, either a method of kneading the rubber component and various compounding agents at once or a method of mixing them in several batches can be applied.

[0225] In the present invention, the degree of polymer concentration on the filler surface can be expressed by the bound rubber amount of the modified conjugated diene polymer at 25° C. The bound rubber amount in the rubber composition after completion of the above-mentioned kneading is preferably 15% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving abrasion resistance and breaking strength.

[0226] The rubber composition may be a vulcanized composition that has been vulcanized with a vulcanizing agent. Examples of the vulcanizing agent that can be used include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of the sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds.

[0227] The amount of the vulcanizing agent used is not particularly limited, but is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, relative to 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, for example, preferably 120°C to 200°C, and more preferably 140°C to 180°C.

[0228] In vulcanization, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, a conventionally known material may be used, and examples thereof include sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. As the vulcanization aid, zinc oxide, stearic acid, etc. may be used.

[0229] The amount of the vulcanization accelerator used is not particularly limited, but is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, based on 100 parts by mass of the conjugated diene copolymer.

[0230] In order to improve processability, the rubber composition of the present invention may be blended with a rubber softener. Suitable rubber softeners include mineral oils, liquids, and low molecular weight synthetic softeners.

[0231] Mineral oil-based rubber softeners, called process oils or extender oils, used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthenic rings, and paraffin chains, and those in which the carbon number of the paraffin chain is 50% or more of the total carbon are called paraffinic, those in which the carbon number of the naphthenic ring is 30 to 45% are called naphthenic, and those in which the aromatic carbon number is more than 30% are called aromatic. The rubber softener used in this embodiment is preferably naphthenic and / or paraffinic.

[0232] The amount of the rubber softener to be added is not particularly limited, but is preferably 10 to 80 parts by mass, and more preferably 20 to 50 parts by mass, per 100 parts by mass of the conjugated diene copolymer.

[0233] The rubber composition may contain various additives such as softeners and fillers other than those described above, as well as heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, lubricants, etc., within the scope of the present embodiment. Specific examples of fillers include calcium carbonate, magnesium carbonate, aluminum sulfate, barium sulfate, etc. Softeners that are blended as necessary to adjust the hardness and fluidity of the target product include, for example, liquid paraffin, castor oil, linseed oil, etc. Known materials can be used as heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0234] The crosslinked rubber of the present invention can be obtained by subjecting a rubber composition containing the crosslinking agent of the present invention to a crosslinking treatment.

[0235] The tire components of the present invention are obtained from the cross-linked rubber. For example, the above-mentioned rubber composition is extruded and molded according to the shape of the tire (specifically, the shape of the tread), and the tread is produced by heating and pressurizing the extrusion in a vulcanizer. The tread is then assembled with other components to produce the desired tire.

[0236] The rubber composition of the present invention, when made into a cross-linked rubber product, has excellent mechanical strength and abrasion resistance. Therefore, as described above, it can be suitably applied to tire components such as treads and sidewall components of tires such as fuel-efficient tires, large tires, and high-performance tires. In addition to the tire components, it can also be suitably used for rubber belts, rubber hoses, footwear materials, etc. EXAMPLES

[0237] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In each example, all parts are by weight unless otherwise specified, and each physical property was evaluated by the following method.

[0238] 1) Molecular weight and molecular weight distribution The molecular weight and molecular weight distribution were measured using GPC (Tosoh Corporation, HLC-8220GPC) with tetrahydrofuran (THF) as the solvent, a flow rate of 1.0 ml / min, a column temperature of 38° C., and a calibration curve based on monodisperse polystyrene.

[0239] 2) Structure of polyfunctional vinyl aromatic copolymer Using a JEOL JNM-LA600 nuclear magnetic resonance spectrometer, 13 C-NMR and 1 The NMR analysis was performed using 1H-NMR spectroscopy. Chloroform-d1 was used as the solvent, and the resonance line of tetramethylsilane was used as the internal standard.

[0240] 3) Mooney viscosity (ML(1+4)100℃) According to JIS K6300-1, the measurements were performed using an L-shaped rotor, 1 minute preheating, 4 minutes rotor operation time, and a temperature of 100°C.

[0241] 4) Haze A sample prepared by dissolving 0.5 g of copolymer 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 (Nippon Denshoku Industries, SZ-Σ90) with toluene as the reference sample.

[0242] 5) Glass transition temperature (Tg) A solution of polyfunctional vinyl aromatic copolymer dissolved in toluene was uniformly applied to a glass substrate so that the thickness after drying was 20 μm, and the substrate was heated for 30 minutes at 90°C using a hot plate and dried. The resin film obtained together with the glass substrate was set in a TMA (thermomechanical analyzer), heated to 220°C at a heating rate of 10°C / min under a nitrogen stream, and further heated at 220°C for 20 minutes to remove the remaining solvent and harden the polyfunctional vinyl aromatic copolymer. After the glass substrate was allowed to cool to room temperature, an analytical probe was brought into contact with the sample in the TMA measuring device, and a scan measurement was performed from 30°C to 360°C at a heating rate of 10°C / min under a nitrogen stream, and the softening temperature was determined by the tangential method.

[0243] 6) Solvent soluble The copolymer was soluble in toluene, xylene, THF, dichloroethane, dichloromethane, and chloroform. When 100 g or more of the copolymer dissolved in 100 g of each of the above solvents and no gel formation was observed, the copolymer was rated as having solvent solubility of ◯.

[0244] 7) Vinyl bond content of conjugated diene units of conjugated diene copolymer The sample was dissolved in carbon disulfide, and the infrared spectrum was recorded from 600 to 1000 cm- using a solution cell. 1 The vinyl bond amount was calculated from the absorbance at a predetermined wave number according to the calculation formula of the Hampton (styrene-butadiene copolymer) method. The device used was a Spectrum 100 manufactured by PerkinElmer.

[0245] 8) Bound rubber content (%) A mixture of 100 parts by mass of modified conjugated diene polymer and wet silica (BET specific surface area: 205±10 m 2 Using an enclosed mixer with a mixing chamber volume of 2 liters, 60 parts by mass of rubber composition (trade name "Nipsil AQ") and 60 parts by mass of rubber composition (trade name "Nipsil AQ" manufactured by Tosoh Silica Co., Ltd.) are mixed at a ratio of 60% {(volume of rubber composition being mixed / volume of mixing chamber) x 100}, and when the maximum mixing temperature of 160°C is reached, the rubber mixture is discharged to obtain rubber composition M for measuring the amount of bound rubber. 0.2 g of this rubber composition M was cut into 1 mm squares and the mass was measured, then added to 25 mL of toluene and left at 25°C for 48 hours. Then, it was filtered through an ADVANTEC glass fiber filter to separate the toluene insolubles, which were then vacuum dried at 25°C and weighed to determine the amount of bound rubber using the following formula. Bound rubber amount (%)={(mass of toluene insoluble matter−mass of wet silica in rubber composition M) / (mass of rubber composition M−mass of wet silica in rubber composition M)}×100 The BET specific surface area of ​​silica is measured in accordance with ISO 5794 / 1.

[0246] 9) Tensile strength The 300% modulus was measured by the tensile test method of JIS K6251, and indexed with the measured value of the crosslinked rubber obtained in Example 7 set at 100. A larger index value indicates better tensile strength.

[0247] 10) Abrasion resistance The amount of wear at a slip rate of 30% was measured using a Lambourn type abrasion tester in accordance with JIS K6264, and indexed with the measured value of the crosslinked rubber obtained in Example 10 set at 100. The larger the index value, the better the abrasion resistance.

[0248] The raw materials or their abbreviations used in the examples are as follows. DVB-630; a mixture of divinylbenzene component (DVB) and ethylvinylbenzene component (EVB), DVB and EVB are (a mixture of m- and p-compounds); DVB content 63.0 wt%, manufactured by Nippon Steel Chemical & Materials Co., Ltd.) BHT; 2,6-di-tert-butyl-p-cresol BTESPA; Bis(3-trimethoxysilylpropyl)methylamine

[0249] Synthesis Example 1 31.00g of DVB-630 (0.150 mol of DVB, 0.088 mol of EVB), 65.72g of styrene (0.631 mol), 70.80g of diisobutylene (0.631 mol), 60 mmol of n-propyl acetate (6.90 mL), and 48.55g of toluene (0.527 mol) were charged into a 500 mL reactor, and 15.2 mmol of boron trifluoride diethyl ether complex (1.91 mL) was added at 70 ° C. and reacted for 2.0 hours. After the polymerization solution was stopped with an aqueous sodium bicarbonate solution, the oil layer was washed three times with pure water, and the copolymer was removed under reduced pressure at 60 ° C. to recover 60.6g of a polyfunctional vinyl aromatic copolymer (copolymer A-1).

[0250] The copolymer A-1 had an Mn of 941, an Mw of 2850, and an Mw / Mn of 3.03. It also contained 19.0 mol % (21.8 wt %) of structural units derived from DVB, 8.3 mol % (9.6 wt %) of structural units derived from EVB, 48.6 mol % (44.6 wt %) of structural units derived from styrene, and 24.2 mol % (24.0 wt %) of structural units derived from diisobutylene. The crosslinked structural units (a1) were 4.6 mol % (5.2 wt %), and the crosslinking degree (a1 / a) was 0.24. The structural units (a2) having residual vinyl groups were 14.4 mol % (16.5 wt %), and the molar fraction of the structural units (a2) relative to the sum of the structural units (a), (b), and (c) was 0.144. The cured product had a Tg of 167° C. and a softening temperature of over 280° C. The weight loss at 350° C. was 1.41 wt%. In addition, a sample prepared by dissolving 0.5 g of the polyfunctional vinyl aromatic copolymer (A-1) in 100 g of toluene was placed in a quartz cell, and the haze (turbidity) of the sample was measured using an integrating sphere type light transmittance measuring device with toluene as a reference sample. The haze value was 0.02.

[0251] Example 1 50.0 g of the copolymer A-1 and 50.0 g of ethylcyclohexane were charged into a 300 mL three-neck flask and degassed with nitrogen while stirring for 3 hours at 60° C. 0.032 g of t-butylperoxy 2-ethylhexanoate and 30.6 g of (3-mercaptopropyl)trimethoxysilane (MPTMS) were added and reacted at 90° C. for 8 hours to obtain 80.6 g of modified vinyl aromatic copolymer (copolymer A-2) in terms of solid content.

[0252] Example 2 Into a nitrogen-purged autoclave reactor, 200 g of cyclohexane and 5 g of a cyclohexane solution containing 6.2 mg (0.032 mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and 5 g of a cyclohexane solution containing 10 mg (0.16 mmol) of n-butyllithium was added at 50°C, followed by the addition of 10 g of styrene and 40 g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 81°C. After the polymerization reaction was completed, 5 g of a cyclohexane solution containing 0.031 g of the copolymer A-2 obtained in Example 1 as a modifier was added to the reactor to carry out a modification reaction. The modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer A-3) was obtained.

[0253] Synthesis Example 2 46.49g of DVB-630 (0.225 mol of DVB, 0.132 mol of EVB), 53.33g of styrene (0.512 mol), 70.80g of diisobutylene (0.631 mol), 60 mmol of n-propyl acetate (6.90 mL), and 48.55g of toluene (0.527 mol) were charged into a 500 mL reactor, and 10.0 mmol of boron trifluoride diethyl ether complex (1.26 mL) was added at 70 ° C. and reacted for 2.0 hours. After the polymerization solution was stopped with an aqueous sodium bicarbonate solution, the oil layer was washed three times with pure water, and the copolymer was removed under reduced pressure at 60 ° C. to recover 66.4g of a polyfunctional vinyl aromatic copolymer (copolymer B-1).

[0254] The copolymer B-1 had an Mn of 1240, an Mw of 4980, and an Mw / Mn of 4.02. It also contained 28.2 mol% (31.5 wt%) of structural units derived from DVB, 12.2 mol% (13.8 wt%) of structural units derived from EVB, 37.6 mol% (33.6 wt%) of structural units derived from styrene, and 22.0 mol% (21.1 wt%) of structural units derived from diisobutylene. It also contained 7.6 mol% (8.5 wt%) of crosslinked structural units (a1), and the degree of crosslinking was 0.27. It also contained 20.6 mol% (23.0 wt%) of structural units (a2), and the molar fraction of structural units (a2) was 0.206. The cured product had a Tg of 176° C., a softening temperature of 280° C. or higher, and a weight loss of 1.32 wt % at 350° C. The haze value was 0.03.

[0255] Example 3 50.0 g of the copolymer B-1 obtained in Synthesis Example 2 and 50.0 g of ethylcyclohexane were charged into a 300 mL three-neck flask and degassed with nitrogen while stirring for 3 hours at 60° C. 0.036 g of t-butylperoxy 2-ethylhexanoate and 34.5 g of (3-mercaptopropyl)trimethoxysilane were added and reacted at 90° C. for 8 hours to obtain 84.5 g of a modified vinyl aromatic copolymer (copolymer B-2) in terms of solid content.

[0256] Example 4 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the polymerization heat, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.027g of the copolymer B-2 obtained in Example 3 was added to the reactor as a modifier, and a modification reaction was carried out. The modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer B-3) was obtained.

[0257] Synthesis Example 3 62.00g of DVB-630 (0.300 mol of DVB, 0.176 mol of EVB), 40.92g (0.393 mol) of styrene, 70.80g (0.631 mol) of diisobutylene, 60 mmol of n-propyl acetate (6.90 mL), and 48.55g (0.527 mol) of toluene were charged into a 500 mL reactor, and 8.2 mmol of boron trifluoride diethyl ether complex (1.03 mL) was added at 70 ° C. and reacted for 1.5 hours. After the polymerization solution was stopped with an aqueous sodium bicarbonate solution, the oil layer was washed three times with pure water, and the copolymer was removed under reduced pressure at 60 ° C. to recover the copolymer, and 56.3g of a polyfunctional vinyl aromatic copolymer (copolymer C-1) was obtained.

[0258] The obtained copolymer C-1 had an Mn of 1430, an Mw of 5490, and an Mw / Mn of 3.84. It also contained 39.4 mol% (42.6 wt%) of structural units derived from DVB, 15.9 mol% (17.4 wt%) of structural units derived from EVB, 25.7 mol% (22.2 wt%) of structural units derived from styrene, and 19.1 mol% (17.8 wt%) of structural units derived from diisobutylene. The crosslinked structural units (a1) were 11.4 mol% (12.3 wt%), and the crosslinking degree was 0.29. The structural units (a2) were 28.0 mol% (30.2 wt%), and the molar fraction thereof was 0.280. The cured product had a Tg of 183° C. and a softening temperature of 280° C. or higher. The weight loss at 350° C. was 1.28 wt %. The haze value was 0.05.

[0259] Example 5 50.0 g of the copolymer C-1 obtained in Synthesis Example 3 and 50.0 g of ethylcyclohexane were charged into a 300 mL three-neck flask and degassed with nitrogen while stirring for 3 hours at 60° C. 0.044 g of t-butylperoxy 2-ethylhexanoate and 42.3 g of (3-mercaptopropyl)trimethoxysilane (MPTMC) were added and reacted at 90° C. for 8 hours to obtain 92.3 g of a modified vinyl aromatic copolymer (copolymer C-2) in terms of solid content.

[0260] Example 6 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the polymerization heat, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.023g of the copolymer C-2 obtained in Example 5 was added to the reactor as a modifier, and a modification reaction was carried out. The modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer C-3) was obtained.

[0261] Comparative Example 1 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium was added, followed by adding 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.021g of the copolymer (C-1) obtained in Synthesis Example 3 as a branching agent was added to the reactor, and a branching reaction was carried out. A modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.16 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer D-3) was obtained.

[0262] Comparative Example 2 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium was added, followed by the addition of 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, reaching a maximum temperature of 81°C. After the polymerization reaction was completed, 0.16mmol of BTESPA was added to the reactor and the modification reaction was carried out for 30 minutes to obtain a modified conjugated diene copolymer-containing polymer solution. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer E-3 was obtained. The analytical results of each copolymer are shown in Tables 1 and 2.

[0263] [Table 1]

[0264] [Table 2]

[0265] Example 7 The copolymer A-3 (copolymer rubber) obtained in Example 2, process oil, carbon black, zinc oxide, stearic acid and an antioxidant were blended and kneaded at 155° C. and 60 rpm for 4 minutes using a Labo Plastomill. To the kneaded product obtained by the above kneading, sulfur and a vulcanization accelerator were added, and the mixture was kneaded at 70° C. and 60 rpm for 1 minute using a Labo Plastomill, and vulcanized to obtain a crosslinked rubber A. The compounding ratio (parts by weight) is shown in Table 3. The physical properties of the crosslinked rubber A are shown in Table 4.

[0266] [Table 3]

[0267] The additives used are as follows: Process oil: Idemitsu Kosan Dyna Process Oil AC-12 Silica: Degussa, ULTRASIL VN3 Carbon black: Nitelon #300 made by Shinnikka Carbon Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Stearic acid: NOF Corporation Anti-aging agent: Noccela NS manufactured by Ouchi Shinko Chemical Industry Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Accelerator: N-tert-butylbenzothiazole-2-sulfenamide

[0268] Examples 8 to 9, Comparative Examples 3 to 4 The crosslinked rubbers B to F were obtained in the same manner as in Example 7, except that the modified conjugated diene copolymers B-3, C-3, D-3 or E-3 synthesized in Examples 4 and 6, or Comparative Examples 1 to 2, were used instead of the modified conjugated diene copolymer A-3. Table 4 shows the type of modified conjugated diene copolymer used and the physical properties of the resulting crosslinked rubbers B to E.

[0269] [Table 4]

[0270] From Table 4, it can be seen that the cross-linked rubber using the copolymer of the present invention gives equal or greater silica dispersibility and adhesion at the interface compared to the case where a known branching agent, divinylbenzene, is used, and therefore the vulcanized rubber has excellent tensile strength and abrasion resistance.

[0271] Example 11 270ml (210.3g) of cyclohexane and 5g of cyclohexane solution containing 1.05g (9.0mmol) of N,N,N',N'-tetramethylethylenediamine were charged, and 50g of cyclohexane solution containing 2.88g (45.0mmol) of n-butyllithium was added at 50°C. Then, 4.73g (22.9mmol of DVB-630, 13.4mmol of EVB) and 27.96g (269mmol) of styrene, which had been previously removed of impurities, were added to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 10.63g (45.0mmol) of 3-glycidoxypropyltrimethoxysilane (GPTMS) was added as a modifier to the reactor and the modification reaction was carried out for 30 minutes to obtain a modified vinyl aromatic copolymer-containing polymer solution. The resulting polymerization solution was concentrated by devolatilization to obtain 42.89 g (yield: 99.0 wt %) of a modified vinyl aromatic copolymer (copolymer A-11) calculated as solid content.

[0272] Copolymer A-11 had an Mn of 4520, an Mw of 8870, and an Mw / Mn of 1.96. It also contained 6.55 mol% (6.88 wt%) of structural units derived from DVB, 3.79 mol% (4.04 wt%) of structural units derived from EVB, 76.8 mol% (64.5 wt%) of structural units derived from styrene, and 12.9 mol% (24.5 wt%) of structural units derived from 3-glycidoxypropyltrimethoxysilane. It also contained 6.55 mol% (6.88 wt%) of crosslinked structural units (a1), and a crosslinking degree (a1 / a) of 1.00. It also contained 0.0 mol% of structural units (a2) having residual vinyl groups. The weight loss at 350° C. was 1.25 wt %, and the haze value was 0.02.

[0273] Example 12 270ml (210.3g) of cyclohexane and 5g of cyclohexane solution containing 1.05g (9.0mmol) of N,N,N',N'-tetramethylethylenediamine were charged, and 50g of cyclohexane solution containing 2.88g (45.0mmol) of n-butyllithium was added at 50℃. Then, 4.73g of DVB-630 (divinylbenzene (mixture of m- and p-forms) component 22.9mmol, ethylvinylbenzene (mixture of m- and p-forms) component 13.4mmol) from which impurities had been removed in advance, and 27.96g (269mmol) of styrene were added to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 81℃. After the polymerization reaction was completed, 16.14 g (45.0 mmol) of triethoxylthiopropyltrimethoxysilane (TESTPTMS) was added as a modifier to the reactor and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified vinyl aromatic copolymer (copolymer B-11). The resulting polymerization solution was concentrated by devolatilization to obtain 48.34 g (yield: 99.0 wt %) of modified vinyl aromatic copolymer B-11 in terms of solid content.

[0274] The copolymer B-11 had an Mn of 2190, an Mw of 3620, and an Mw / Mn of 1.65. It also contained 6.56 mol% (6.10 wt%) of structural units derived from DVB, 3.78 mol% (3.58 wt%) of structural units derived from EVB, 76.8 mol% (57.3 wt%) of structural units derived from styrene, and 12.8 mol% (33.1 wt%) of structural units derived from 3-glycidoxypropyltrimethoxysilane. The crosslinked structural units (a1) were 6.55 mol% (6.09 wt%), and the degree of crosslinking was 1.00. The structural units (a2) were 0.0 mol%. The weight loss at 350°C was 1.39 wt%, and the haze value was 0.03. The analytical results of the copolymers of Examples 11 and 12 are shown in Table 5.

[0275] [Table 5]

[0276] Example 13 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the polymerization heat, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.076g of the modified vinyl aromatic copolymer (A-11) obtained in Example 11 was added to the reactor as a modifier, and a modification reaction was carried out. The modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the obtained polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and then the solvent was removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer A-12) was obtained.

[0277] Example 14 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.085g of the copolymer B-11 obtained in Example 12 as a modifier was added to the reactor, and a modification reaction was carried out. The modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the obtained polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and then the solvent was removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer B-12) was obtained.

[0278] Synthesis Example 11 31.00g of DVB-630 (0.150 mol of DVB, 0.088 mol of EVB), 65.72g of styrene (0.631 mol), 70.80g of diisobutylene (0.631 mol), 60 mmol of n-propyl acetate (6.90 mL), and 48.55g of toluene (0.527 mol) were charged into a 500 mL reactor, and 15.2 mmol of boron trifluoride diethyl ether complex (1.91 mL) was added at 70 ° C. and reacted for 2.0 hours. After the polymerization solution was stopped with an aqueous sodium bicarbonate solution, the oil layer was washed three times with pure water, and the copolymer was removed under reduced pressure at 60 ° C. to recover 60.6g of vinyl aromatic copolymer (copolymer C-11).

[0279] The obtained copolymer C-11 had an Mn of 941, an Mw of 2850, and an Mw / Mn of 3.03. It also contained 19.0 mol% (21.8 wt%) of structural units derived from DVB, 8.3 mol% (9.6 wt%) of structural units derived from EVB, 48.6 mol% (44.6 wt%) of structural units derived from styrene, and 24.2 mol% (24.0 wt%) of structural units derived from diisobutylene. The crosslinked structural units (a1) were 4.6 mol% (5.2 wt%), and the degree of crosslinking was 0.24. The structural units (a2) were 14.4 mol% (16.5 wt%), and the molar fraction thereof was 0.144. The cured product had a Tg of 167° C. and a softening temperature of 280° C. or higher. The weight loss at 350° C. was 1.41 wt %. The haze value was 0.02.

[0280] Comparative Example 11 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 81°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.021g of the copolymer C-11 obtained in Synthesis Example 11 as a branching agent was added to the reactor, and a branching reaction was carried out. A modification reaction was carried out for 30 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.16 mmol of BTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the obtained polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and then the solvent was removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer C-12) was obtained.

[0281] Comparative Example 12 In the same manner as in Comparative Example 2, a modified conjugated diene copolymer (copolymer D-12) was obtained. The analytical results of the obtained copolymer are shown in Table 6.

[0282] [Table 6]

[0283] Example 15 The copolymer A-12 (copolymer rubber) obtained in Example 13, process oil, carbon black, zinc oxide, stearic acid and an antioxidant were blended and kneaded at 155° C. and 60 rpm for 4 minutes using a Labo Plastomill. To the kneaded product obtained by the above kneading, sulfur and a vulcanization accelerator were added, and the mixture was kneaded at 70° C. and 60 rpm for 1 minute using a Labo Plastomill, and vulcanized to obtain a crosslinked rubber A. The blending ratio and additives used were the same as in Example 7 and Table 3.

[0284] Example 16, Comparative Examples 13 to 14 The crosslinked rubbers B to D were obtained in the same manner as in Example 15, except that the copolymers B-12, C-12, or D-12 obtained in Example 14 or Comparative Examples 11 to 12 were used instead of the modified conjugated diene copolymer A-12. Table 7 shows the type of modified conjugated diene copolymer used and the physical properties of the resulting crosslinked rubbers B to D.

[0285] [Table 7]

[0286] Example 17 240ml (186.96g) of ethylcyclohexane and 2.31g (12.0mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged into the reactor, and 37.5g of n-hexane solution containing 3.84g (60.0mmol) of n-butyllithium was added at 50°C. Then, 6.37g (30.0mmol of DVB-630, 18.9mmol of EVB) and 38.65g (371.1mmol) of styrene, from which impurities had been removed, were added to initiate polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 67°C. After the polymerization reaction was completed, 16.94g (60.9mmol) of 3-glycidoxypropyltriethoxysilane (GPTES) was added as a modifier to the reactor and the modification reaction was carried out for 60 minutes to obtain a polymer solution containing a functional group-modified vinyl aromatic copolymer. The resulting polymerization solution was neutralized with succinic acid and then filtered. The resulting polymerization solution was concentrated by devolatilization to obtain 61.34 g (yield: 99.0 wt %) of a functional group-modified vinyl aromatic copolymer (copolymer F-2) calculated as solid content. The analytical results of copolymer F-2 are shown in Table 8.

[0287] Copolymer F-2 contained 6.24 mol% (6.30 wt%) of structural units derived from divinylbenzene, 3.93 mol% (3.98 wt%) of structural units derived from ethylvinylbenzene, 77.17 mol% (62.38 wt%) of structural units derived from styrene, and 12.66 mol% (27.34 wt%) of structural units derived from GPTES. The crosslinked structural units (a1) were 6.05 mol% (6.11 wt%), and the crosslinking degree (a1 / a) was 0.97. In addition, the structural units (a2) derived from divinylbenzene having residual vinyl groups were 0.19 mol% (0.19 wt%), so the molar fraction of the structural units (a2) relative to the sum of the structural units (a) and (b) was 0.0021.

[0288] Example 18 240 ml (186.96 g) of ethylcyclohexane and 2.31 g (12.0 mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and 37.5 g of n-hexane solution containing 3.84 g (60.0 mmol) of n-butyllithium was added at 50°C. Then, 8.92 g (42.0 mmol) of DVB-630 (42.0 mmol of DVB, 26.5 mmol of EV) and 42.86 g (411.5 mmol) of styrene, which had been previously removed of impurities, were added to start polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 65°C. After the polymerization reaction was completed, 16.94 g (60.9 mmol) of GPTES was added as a modifier to the reactor and the modification reaction was carried out for 60 minutes to obtain a polymer solution containing a functional group-modified vinyl aromatic copolymer. The obtained polymerization solution was neutralized using succinic acid and then filtered. The resulting polymerization solution was concentrated by devolatilization to obtain 68.31 g (yield: 99.4 wt %) of a modified vinyl aromatic copolymer (copolymer G-2) calculated as solid content. The analytical results of copolymer G-2 are shown in Table 8.

[0289] Copolymer G-2 contained 7.77 mol% (7.96 wt%) of structural units derived from DVB, 4.90 mol% (5.02 wt%) of structural units derived from EVB, 76.09 mol% (62.37 wt%) of structural units derived from styrene, and 11.25 mol% (24.66 wt%) of structural units derived from GPTES. The crosslinked structural units (a1) were 7.45 mol% (7.64 wt%), and the crosslinking degree (a1 / a) was 0.96. The structural units (a2) were 0.31 mol% (0.32 wt%), and the molar fraction of the structural units (a2) relative to the sum of the structural units (a) and (b) was 0.0035.

[0290] [Table 8]

[0291] Example 19 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 76°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.081g of the copolymer F-2 obtained in Example 17 as a modifier was added to the reactor, and a modification reaction was carried out. The modification reaction was carried out for 60 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of BTESPABTESPA was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer F-3) was obtained.

[0292] Example 20 Into a nitrogen-substituted autoclave reactor, 200g of cyclohexane and 5g of a cyclohexane solution containing 6.2mg (0.032mmol) of 2,2-di(2-tetrahydrofuryl)propane were charged, and at 50°C, 5g of a cyclohexane solution containing 10mg (0.16mmol) of n-butyllithium as a pure content was added, and then 10g of styrene and 40g of 1,3-butadiene from which impurities had been removed in advance were added to start polymerization. The temperature of the reaction solution rose due to the heat of polymerization, and the maximum temperature reached 77°C. After the polymerization reaction was completed, 5g of a cyclohexane solution containing 0.090g of the copolymer G-2 obtained in Example 18 as a modifier was added to the reactor, and a modification reaction was carried out. The modification reaction was carried out for 60 minutes at a temperature condition of 50°C to obtain a polymer solution. Further, 0.08 mmol of bis(3-triethoxysilylpropyl)methylamine was added and the modification reaction was carried out for 30 minutes to obtain a polymer solution containing a modified conjugated diene copolymer. To the resulting polymerization solution, 0.045 g of 2,6-di-tert-4-hydroxytoluene was added as an antioxidant, and the solvent was then removed by steam stripping. After vacuum drying, a modified conjugated diene copolymer (copolymer G-3) was obtained. The analytical results of the obtained copolymer are shown in Table 9.

[0293] [Table 9] Examples 21-22 Crosslinked rubbers F to G were obtained in the same manner as in Example 15, except that copolymer F-3 or G-3 was used. Table 10 shows the type of modified conjugated diene copolymer used and the physical properties of the resulting crosslinked rubbers F to G.

[0294] [Table 10] [Industrial Applicability]

[0295] The modified vinyl aromatic copolymer of the present invention can be used as a raw material for conjugated diene copolymers. Furthermore, the crosslinked rubber composition obtained by crosslinking this conjugated diene copolymer with a filler has excellent filler dispersibility, mechanical strength, and abrasion resistance, and is therefore useful as an elastomer material for tires (especially tire treads), seismic isolation rubber, rubber hoses, rubber rollers, footwear materials, etc. In addition, the polymer or a composition containing the polymer is useful as a molding material, a resin modifier, a dielectric material, an insulating material, a heat-resistant material, a structural material, an optical material, etc.

Claims

1. A modified vinyl aromatic copolymer containing a structural unit (a) derived from a divinyl aromatic compound and a structural unit (b) derived from a monovinyl aromatic compound, wherein at least a part of the structural unit (a) is the following crosslinked structural unit (a1): 【Chemistry 1】 (Here, R 1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. A modified vinyl aromatic copolymer characterized in that one or more of the terminals are modified with a modifying group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group, the number average molecular weight Mn measured using gel permeation chromatography in terms of standard polystyrene is 500 to 10,000, the degree of crosslinking is 0.20 or more, and the copolymer is soluble in a solvent selected from toluene, xylene, tetrahydrofuran, dichloroethane, and chloroform at a rate of 50 g or more per 100 g of solvent, and the copolymer contains 0.5 mol % to 95.0 mol % of the structural unit (a) relative to the total of the structural units (a) and (b), and the content of structural units other than the structural units (a) and (b) is at most 50 mol %.

2. The copolymer has a side chain or an end thereof represented by the following formula (c1) or (c2): 【Chemistry 2】 (Here, R ２ is a divalent alkylene group having 1 to 6 carbon atoms, R ３ , R ４ , R ５ , R ７ , R ８ and R ９ each independently represents a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, a benzyloxy group, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a phenyl group, or a benzyl group. ３ , R ４ and R ５ At least one of, or R ７ , R ８ and R ９ At least one of is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, or a benzyloxy group. Contains one or more types of silane-based functional groups (c) represented by the molar fraction of the crosslinked structural unit (a1) relative to the structural unit (a) is in the range of 0.20 to 0.90; The silane functional group (c) is 1 to 20 per molecule.

2. The modified vinyl aromatic copolymer according to claim 1, wherein the molecular weight distribution (Mw / Mn), which is expressed as the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, is 30.0 or less.

3. 3. The modified vinyl aromatic copolymer according to claim 2, comprising at least one copolymer represented by any one of the following formulas (2) to (13): 【Chemistry 3】 (In the formula, R ２ is a divalent alkylene group having 1 to 6 carbon atoms, R ３ , R ４ and R ５ each independently represents a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, a benzyloxy group, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a phenyl group, or a benzyl group. ３ , R ４ and R ５ At least one of R is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, or a benzyloxy group. ６ is an alkyl group having 1 to 6 carbon atoms, a vinyl group, or hydrogen. olymer is a copolymer chain. However, the benzene ring in the formula can be any aromatic ring. 【Chemistry 4】 (In the formula, R ７ , R ８ and R ９ each independently represents a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, a benzyloxy group, a methyl group, an ethyl group, a propyl group, a butyl group, a cyclohexyl group, a phenyl group, or a benzyl group. ７ , R ８ and R ９ At least one of R is a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octoxy group, a lauryloxy group, a phenoxy group, or a benzyloxy group. ６ is an alkyl group having 1 to 6 carbon atoms, a vinyl group, or hydrogen. Polymer is a copolymer chain.

4. The modified vinyl aromatic copolymer according to claim 2 or 3, wherein the structural unit (b) derived from a monovinyl aromatic compound is a structural unit derived from 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.

5. A method for producing the modified vinyl aromatic copolymer according to any one of claims 2 to 4 from a polyfunctional vinyl aromatic copolymer and a silane compound, comprising the steps of: The polyfunctional vinyl aromatic copolymer contains 0.5 mol % or more and 95.0 mol % or less of a structural unit (a) derived from a divinyl aromatic compound, and contains 5.0 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound; At least a part of the structural unit (a) is the above-mentioned crosslinked structural unit (a1) and the following vinyl group-containing structural unit (a2), 【Chemistry 5】 (In the formula, R 1 represents an aromatic hydrocarbon group having 6 to 30 carbon atoms. the molar fraction of the crosslinked structural unit (a1) relative to the structural unit (a) is in the range of 0.20 to 0.90; the molar fraction of the vinyl group-containing structural unit (a2) relative to the sum of the structural units (a) and (b) is in the range of 0.001 to 0.80; A polyfunctional vinyl aromatic copolymer having a Mw / Mn of 20.0 or less, The silane-based compound is a silane-based compound represented by the following formula (5) and / or formula (6): 【Chemistry 6】 (In the formula, R ２ , R ３ , R ４ and R ５ is the same as formula (c1) above.) 【Chemistry 7】 (In the formula, R ６ , R ７ and R ８ is R in the above formula (c2) ７ , R ８ and R ９ is the same as A method for producing a modified vinyl aromatic copolymer, comprising dissolving the polyfunctional vinyl aromatic copolymer and a silane compound in a hydrocarbon solvent and adding the polyfunctional vinyl aromatic copolymer and the silane compound at a temperature of 0 to 150°C in the presence of a catalyst.

6. A modified conjugated diene polymer, which is obtained by reacting a polymer of a conjugated diene compound (B) having an active end, or a copolymer of a conjugated diene compound (B) having an active end and an aromatic vinyl compound (C), with the modified vinyl aromatic copolymer (A) according to any one of claims 2 to 4 as a modifier.

7. The modified conjugated diene copolymer according to claim 6, which contains 0.001 to 6 wt% of the structural unit (A1) derived from the modified vinyl aromatic copolymer (A), 29 to 99.999 wt% of the structural unit (B1) derived from the conjugated diene compound (B), and 0 to 70 wt% of the structural unit (C1) derived from the aromatic vinyl compound (C).

8. 8. The modified conjugated diene copolymer according to claim 6 or 7, wherein, in a differential molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement, when the total area is taken as 100%, the area of ​​a region having a number average molecular weight (Mn) three times or more of the lowest molecular weight peak is 10% or more.

9. A modified conjugated diene copolymer composition, comprising the modified conjugated diene copolymer according to any one of claims 6 to 8, and at least one reinforcing filler selected from the group consisting of a filler or a silica-based inorganic filler, a metal oxide, a metal hydroxide, and carbon black.

10. The modified conjugated diene copolymer composition according to claim 9, further comprising a crosslinking agent.

11. A cross-linked rubber product obtained by cross-linking the modified conjugated diene copolymer composition according to claim 10.

12. A tire component comprising the cross-linked rubber according to claim 11.

13. 95 mol % or more of the structural units (a) are the crosslinked structural units (a1), The modified vinyl aromatic copolymer according to claim 1, characterized in that two or more of the terminals are modified with a modifying group having at least one functional group selected from the group consisting of an amino group, an alkoxysilyl group, and a hydroxyl group.

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