Rubber composition for tires, tread rubber for tires, and tire

Abstract

To provide a rubber composition for tires which has improved workability in kneading while maintaining fracture-resistant performance.SOLUTION: The rubber composition for tires contains a rubber component, a resin component, and a filler and contains or does not contain an oil. The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber. The content of the resin component is 1 pt.mass or more and less than 50 pts.mass based on 100 pts.mass of the rubber component. The resin component has been at least partially hydrogenated. A relationship of the following formula is satisfied: 0.70≤((the number of parts by mass of the resin component)-(the number of parts by mass of the oil)) / (the number of parts by mass of the isoprene skeleton rubber)≤1.18.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a rubber composition for tires, a tread rubber for tires, and a tire. [Background technology]

[0002] Conventionally, from the viewpoint of improving vehicle safety, various studies have been made to improve the braking performance on wet road surfaces (hereinafter, abbreviated as "wet grip performance"). For example, the following Patent Document 1 discloses that the braking performance of tires on both dry and wet road surfaces is improved by applying a rubber composition obtained by blending a rubber component containing 70% by mass or more of natural rubber with a resin (thermoplastic resin) and a filler containing silica to the tread rubber of the tire. Also, a method is known in which a softener such as a resin or oil is added to reduce the unvulcanized viscosity of the rubber composition and improve the workability during kneading of the rubber composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 079703 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a softener is added to a rubber composition in order to reduce the unvulcanized viscosity of the rubber composition, the fracture resistance of the rubber composition deteriorates.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a rubber composition for tires which improves workability in kneading while maintaining fracture resistance, and a tire tread rubber made of such a rubber composition. Another object of the present invention is to provide a tire which can be manufactured with improved productivity while maintaining the fracture resistance. [Means for solving the problem]

[0006] The essential features of the rubber composition for tires, tread rubber for tires, and tire of the present invention that solve the above problems are as follows.

[0007] [1] A rubber composition for tires, comprising a rubber component, a resin component, and a filler, with or without oil, The rubber component includes an isoprene skeleton rubber and a styrene-butadiene rubber, The content of the resin component is 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the rubber component, the resin component is at least partially hydrogenated; The following formula (1): 0.70≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene-skeleton rubber≦1.18 (1) The rubber composition for tires is characterized by satisfying the following relationship. The rubber composition for a tire of the present invention described in [1] above has improved workability in kneading while maintaining its fracture resistance.

[0008] [2] The rubber composition for tires according to [1], wherein the styrene-butadiene rubber has a glass transition temperature of less than -40°C. The rubber composition for tires described in the above item [2] can be applied to tires to improve fuel economy and wear resistance of the tires.

[0009] [3] The resin component has an SP value difference of 1.40 (cal / cm 3 ) 1 / 2 The rubber composition for tires according to [1] or [2] below. The rubber composition for a tire according to the above item [3] can improve the wet grip performance of the tire by applying it to a tire.

[0010] [4] The resin component has an SP value difference of 0.50 (cal / cm 3 ) 1 / 2 The rubber composition for tires according to [3], The rubber composition for a tire according to the above item [4] can further improve the wet grip performance of the tire by applying it to a tire.

[0011] [5] The difference in SP value between the isoprene skeleton rubber and the styrene-butadiene rubber is 0.3 (cal / cm 3 ) 1 / 2 The rubber composition for a tire according to any one of [1] to [4] above. In the rubber composition for tires described in the above item [5], the isoprene skeleton rubber and the styrene-butadiene rubber tend to be incompatible with each other.

[0012] [6] The rubber composition for tires according to any one of [1] to [5], wherein the amount of the isoprene skeleton rubber is 1 to 80 parts by mass per 100 parts by mass of the rubber component. The rubber composition for a tire according to the above item [6] can improve the fuel economy and wet grip performance of the tire by applying it to the tire.

[0013] [7] The rubber composition for tires according to [6], wherein the content of the isoprene skeleton rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component. The rubber composition for a tire according to the above item [7] can be applied to a tire to further improve the fuel economy and wet grip performance of the tire.

[0014] [8] The rubber composition for a tire according to any one of [1] to [7], wherein the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group. The rubber composition for a tire according to the above item [8] can improve the balance of wet grip performance, fuel economy, and wear resistance of the tire by applying it to the tire.

[0015] [9] The rubber composition for a tire according to any one of [1] to [8], wherein the resin component has a softening point higher than 110° C. and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol. The rubber composition for a tire according to the above item [9] can improve the wear resistance of the tire by applying it to the tire.

[0016]

[10] The rubber composition for a tire according to [9], wherein the resin component has a weight average molecular weight in terms of polystyrene of 200 to 1200 g / mol. When the rubber composition for tires described in

[10] above is applied to a tire, the resin component is less likely to precipitate from the tire, and the resin component is more easily compatible with the rubber component, so that the effect of the resin component becomes more pronounced.

[0017]

[11] The resin component is hydrogenated C 5 based resin, hydrogenated C 5 -C 9 The rubber composition for tires according to any one of [1] to

[10] , wherein the resin is at least one selected from the group consisting of a cyclopentadiene-based resin, a hydrogenated dicyclopentadiene-based resin, and a hydrogenated terpene-based resin. The rubber composition for a tire according to the above item

[11] can improve the wet grip performance of the tire and reduce the rolling resistance by applying it to the tire.

[0018]

[12] The following formula (1'): 0.79≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene-skeleton rubber≦1.00 (1′) The rubber composition for a tire according to any one of [1] to

[11] , which satisfies the relationship: The rubber composition for tires described in

[11] above maintains the fracture resistance performance more reliably.

[0019]

[13] A tread rubber for a tire, comprising the rubber composition for a tire according to any one of [1] to

[12] . The tire tread rubber of the present invention described in

[13] above has improved workability in production while maintaining the fracture resistance.

[0020]

[14] A tire comprising the tire tread rubber described in

[13] . The tire of the present invention described in

[14] above has improved productivity while maintaining the fracture resistance. Effect of the Invention

[0021] According to the present invention, it is possible to provide a rubber composition for tires which has improved workability in kneading while maintaining fracture resistance, and a tire tread rubber made of such a rubber composition. Moreover, according to the present invention, a tire can be provided that has improved productivity while maintaining the fracture resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The rubber composition for tires, the tread rubber for tires, and the tire of the present invention will be illustrated in detail below based on embodiments.

[0023] <Definition> The compounds described herein may be derived in whole or in part from fossil sources, from biological sources such as plant sources, from recycled sources such as used tires, or from a mixture of two or more of fossil sources, biological sources, and / or renewable sources.

[0024] <Rubber composition for tires> The rubber composition for tires of this embodiment includes a rubber component, a resin component, and a filler, and may or may not include oil. In the rubber composition for tires of this embodiment, the rubber component includes an isoprene skeleton rubber and a styrene-butadiene rubber, the content of the resin component is 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the rubber component, the resin component is at least partially hydrogenated, and a carboxyl group represented by the following formula (1): 0.70≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene-skeleton rubber≦1.18 (1) The above relationship is satisfied.

[0025] In the rubber composition for tires of this embodiment, by blending a resin component (and, optionally, blending oil), the unvulcanized viscosity of the rubber composition is reduced, and workability during kneading can be improved. In addition, in the rubber composition for tires of this embodiment, the content of the resin component is less than 50 parts by mass per 100 parts by mass of the rubber component, and further, the number of parts by mass of the resin component, the number of parts by mass of the oil, and the number of parts by mass of the isoprene skeleton rubber are selected so as to satisfy the relationship of the above formula (1), thereby making it possible to achieve both workability in kneading and fracture resistance performance. Therefore, the rubber composition for a tire of the present embodiment has improved workability during kneading while maintaining the fracture resistance.

[0026] (Rubber component) The rubber composition for a tire of the present embodiment contains a rubber component, and the rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber, and may further contain other rubber components.

[0027] -Isoprene-based rubber- The isoprene skeleton rubber is a rubber having an isoprene unit as the main skeleton, and specific examples thereof include natural rubber (NR) and synthetic isoprene rubber (IR). The inclusion of an isoprene skeleton rubber in the rubber component can increase the breaking strength of the rubber composition, which can reduce the rolling resistance of a tire using the rubber composition, improve fuel economy, and improve the breaking resistance and wear resistance of the tire.

[0028] The content of the isoprene skeleton rubber is preferably 1 to 80 parts by mass, more preferably 1 to 40 parts by mass, in 100 parts by mass of the rubber component. When the content of the isoprene skeleton rubber is 1 to 80 parts by mass, in 100 parts by mass of the rubber component, the fuel economy performance and wet grip performance of a tire to which the rubber composition is applied can be improved. When the content of the isoprene skeleton rubber is 1 to 40 parts by mass, in 100 parts by mass of the rubber component, the fuel economy performance and wet grip performance of a tire to which the rubber composition is applied can be further improved. In addition, from the viewpoint of further increasing the compounding effect of the isoprene skeleton rubber, the content of the isoprene skeleton rubber is more preferably 10 parts by mass or more, in 100 parts by mass of the rubber component.

[0029] -Styrene-butadiene rubber- The styrene-butadiene rubber (SBR) has a glass transition temperature of preferably less than -40°C, more preferably not more than -45°C, further preferably not more than -50°C, and preferably higher than -90°C. When the glass transition temperature of the styrene-butadiene rubber is less than -40°C, the fuel economy and wear resistance of a tire to which the rubber composition is applied can be improved. In addition, a styrene-butadiene rubber having a glass transition temperature higher than -90°C is easy to synthesize.

[0030] The content of the styrene-butadiene rubber is preferably 20 to 99 parts by mass, more preferably 30 to 99 parts by mass, more preferably 40 to 99 parts by mass, more preferably 50 to 99 parts by mass, and even more preferably 60 to 99 parts by mass, in 100 parts by mass of the rubber component. When the content of the styrene-butadiene rubber is 60 to 99 parts by mass in 100 parts by mass of the rubber component, the fuel economy performance and wet grip performance of a tire to which the rubber composition for tires is applied can be further improved.

[0031] The difference in SP value between the isoprene skeleton rubber and the styrene-butadiene rubber is 0.3 (cal / cm 3 ) 1 / 2 It is preferable that the calorie content is 0.35 (cal / cm 3 )1 / 2 It is more preferable that the difference in SP value between the isoprene skeleton rubber and the styrene-butadiene rubber is 0.3 (cal / cm 3 ) 1 / 2 In the above cases, the isoprene skeleton rubber and the styrene-butadiene rubber tend to become incompatible.

[0032] The styrene-butadiene rubber preferably has a bound styrene content of less than 15% by mass. The bound styrene content of the styrene-butadiene rubber means the ratio of styrene units contained in the styrene-butadiene rubber. When the bound styrene content of the styrene-butadiene rubber is less than 15% by mass, the glass transition temperature is likely to be low. The bound styrene content of the styrene-butadiene rubber is more preferably 14% by mass or less, more preferably 13% by mass or less, and even more preferably 12% by mass or less. In addition, from the viewpoint of the wear resistance performance of a tire to which the rubber composition is applied, the bound styrene content of the styrene-butadiene rubber is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 8% by mass or more. The amount of bound styrene in the styrene-butadiene rubber can be adjusted by the amount of monomer used in polymerization of the styrene-butadiene rubber, the degree of polymerization, and the like.

[0033] The styrene-butadiene rubber is preferably modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group. When the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group, the balance of wet grip performance, fuel economy, and wear resistance of a tire to which the rubber composition is applied is improved, and in particular, the fuel economy and wear resistance can be improved. The modifying agent having a functional group containing a nitrogen atom and an alkoxy group is a general term for modifying agents having at least one functional group containing a nitrogen atom and at least one alkoxy group. The functional group containing a nitrogen atom is preferably selected from the following: The functional group is selected from the group consisting of a primary amino group, a primary amino group protected with a hydrolyzable protecting group, an onium salt residue of a primary amine, an isocyanate group, a thioisocyanate group, an imine group, an imine residue, an amide group, a secondary amino group protected with a hydrolyzable protecting group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, a non-cyclic secondary amino group, an onium salt residue of a non-cyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, a non-cyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of a non-cyclic tertiary amine, and is a monovalent hydrocarbon group having 1 to 30 carbon atoms and containing a straight-chain, branched, alicyclic, or aromatic ring, or a monovalent hydrocarbon group having 1 to 30 carbon atoms and containing a straight-chain, branched, alicyclic, or aromatic ring, which may contain at least one heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom.

[0034] --First preferred embodiment of modified styrene-butadiene rubber-- The styrene-butadiene rubber (SBR) is preferably modified with an aminoalkoxysilane compound, and more preferably has its terminals modified with an aminoalkoxysilane compound from the viewpoint of having a high affinity for the filler. When the terminals of the styrene-butadiene rubber are modified with an aminoalkoxysilane compound, the interaction between the modified styrene-butadiene rubber and the filler (particularly silica) becomes particularly large.

[0035] The modified site of the styrene-butadiene rubber may be the molecular terminal as described above, but may also be the main chain. Styrene-butadiene rubber having modified molecular terminals can be produced, for example, by reacting various modifiers with the terminals of a styrene-butadiene copolymer having active terminals according to the methods described in WO 2003 / 046020 and JP 2007-217562 A. In a preferred embodiment, the styrene-butadiene rubber having modified molecular terminals can be produced by reacting an aminoalkoxysilane compound with the terminals of a styrene-butadiene copolymer having active terminals with a cis-1,4 bond content of 75% or more, and then reacting the resulting mixture with a carboxylic acid partial ester of a polyhydric alcohol for stabilization, according to the methods described in WO 2003 / 046020 and JP 2007-217562 A.

[0036] The carboxylic acid partial ester of a polyhydric alcohol means an ester of a polyhydric alcohol and a carboxylic acid, and a partial ester having one or more hydroxyl groups. Specifically, an ester of a sugar or modified sugar having 4 or more carbon atoms and a fatty acid is preferably used. More preferred examples of this ester include (1) a fatty acid partial ester of a polyhydric alcohol, particularly a partial ester (which may be a monoester, diester, or triester) of a saturated higher fatty acid or an unsaturated higher fatty acid having 10 to 20 carbon atoms and a polyhydric alcohol, and (2) an ester compound in which 1 to 3 partial esters of a polycarboxylic acid and a higher alcohol are bonded to a polyhydric alcohol. The polyhydric alcohol used as a raw material for the partial ester is preferably a saccharide having at least three hydroxyl groups and having 5 or 6 carbon atoms (which may or may not be hydrogenated), glycol, polyhydroxy compound, etc. The raw material fatty acid is preferably a saturated or unsaturated fatty acid having 10 to 20 carbon atoms, such as stearic acid, lauric acid, or palmitic acid. Among the fatty acid partial esters of polyhydric alcohols, sorbitan fatty acid esters are preferred, and specific examples thereof include sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate.

[0037] The aminoalkoxysilane compound is not particularly limited, but is preferably an aminoalkoxysilane compound represented by the following general formula (i). R11 a -Si-(OR 12 ) 4-a (i)

[0038] In general formula (i), R 11 and R 12 each independently represents a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms; R 11 and R 12 At least one of the groups is substituted with an amino group, a is an integer of 0 to 2, and OR 12 If there are multiple, each OR 12 may be the same or different, and the molecule does not contain any active protons.

[0039] As the aminoalkoxysilane compound, an aminoalkoxysilane compound represented by the following general formula (ii) is also preferred. [ka]

[0040] In the general formula (ii), n1+n2+n3+n4=4 (wherein n2 is an integer of 1 to 4, and n1, n3 and n4 are integers of 0 to 3). A 1 is at least one functional group selected from a saturated cyclic tertiary amine compound residue, an unsaturated cyclic tertiary amine compound residue, a ketimine residue, a nitrile group, a (thio)isocyanate group, an isocyanuric acid trihydrocarbyl ester group, a nitrile group, a pyridine group, a (thio)ketone group, an amide group, and a primary or secondary amino group having a hydrolyzable group. 1 may be the same or different, and A 1 may be a divalent group that bonds with Si to form a cyclic structure. R 21 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n1 is 2 or more, may be the same or different. R 22is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, either of which may contain a nitrogen atom and / or a silicon atom. 22 may be the same or different, or may be joined together to form a ring. R 23 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom, and when n3 is 2 or greater, may be the same or different. R 24 represents a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when n4 is 2 or greater, may be the same or different. As the hydrolyzable group in the hydrolyzable group-containing primary or secondary amino group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0041] The aminoalkoxysilane compound represented by the above general formula (ii) is preferably an aminoalkoxysilane compound represented by the following general formula (iii). [ka]

[0042] In the general formula (iii), p1+p2+p3=2 (wherein p2 is an integer of 1 or 2, and p1 and p3 are integers of 0 or 1). A 2 is NRa (Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). R 25 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 26is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a nitrogen-containing organic group, any of which may contain a nitrogen atom and / or a silicon atom. 26 may be the same or different, or may be joined together to form a ring. R 27 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a halogen atom. R 28 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. As the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferred, and a trimethylsilyl group is particularly preferred.

[0043] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (iv) or (v). [ka]

[0044] In the general formula (iv), q1+q2=3 (wherein q1 is an integer of 0 to 2, and q2 is an integer of 1 to 3). R 31 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 32 and R 33 are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 34 represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when q1 is 2, may be the same or different. R 35represents a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when q2 is 2 or greater, may be the same or different.

[0045] [ka]

[0046] In the general formula (v), r1+r2=3 (wherein r1 is an integer of 1 to 3, and r2 is an integer of 0 to 2). R 36 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 37 represents a dimethylaminomethyl group, a dimethylaminoethyl group, a diethylaminomethyl group, a diethylaminoethyl group, a methylsilyl(methyl)aminomethyl group, a methylsilyl(methyl)aminoethyl group, a methylsilyl(ethyl)aminomethyl group, a methylsilyl(ethyl)aminoethyl group, a dimethylsilylaminomethyl group, a dimethylsilylaminoethyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be the same or different when r1 is 2 or greater. R 38 represents a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and when r2 is 2, may be the same or different. A specific example of the aminoalkoxysilane compound represented by the general formula (v) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propaneamine.

[0047] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (vi) or (vii). [ka]

[0048] In general formula (vi), R 40 is a trimethylsilyl group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 41 represents a hydrocarbyloxy group having 1 to 20 carbon atoms, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 42 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. Here, TMS represents a trimethylsilyl group (the same applies hereinafter).

[0049] [ka]

[0050] In general formula (vii), R 43 and R 44 are each independently a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 45 is a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and each R 45 may be the same or different.

[0051] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (viii) or (ix). [ka]

[0052] In general formula (viii), s1+s2 is 3 (wherein s1 is an integer of 0 to 2, and s2 is an integer of 1 to 3). R 46is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 47 and R 48 are each independently a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. 47 or R 48 may be the same or different.

[0053] [ka]

[0054] In general formula (ix), X is a halogen atom. R 49 is a divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 50 and R 51 are each independently a hydrolyzable group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or R 50 and R 51 are linked to form a divalent organic group. R 52 and R 53 are each independently a halogen atom, a hydrocarbyloxy group, a monovalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms. R 50 and R 51 As the hydrolyzable group, a hydrolyzable group is preferable, and as the hydrolyzable group, a trimethylsilyl group or a tert-butyldimethylsilyl group is preferable, and a trimethylsilyl group is particularly preferable.

[0055] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (x), the following general formula (xi), the following general formula (xii), or the following general formula (xiii). [ka] [ka] [ka] [ka]

[0056] In the general formulas (x) to (xiii), the symbols U and V each represent an integer of 0 to 2 and satisfying U+V=2. R in general formulas (x) to (xiii) 54 ~ 92 may be the same or different and are a monovalent or divalent aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, or a monovalent or divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. In the general formula (xiii), α and β are integers of 0 to 5.

[0057] Among the compounds satisfying general formula (x), general formula (xi), and general formula (xii), N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine, 2-((hexyl-dimethoxysilyl)methyl)-N1,N1,N3,N3-2-pentamethylpropane-1,3-diamine, N1-(3-(dimethylamino)propyl)-N3,N3-dimethyl-N1-(3-(trimethoxysilyl)propyl)propane-1,3-diamine, and 4-(3-(dimethylamino)propyl)-N1,N1,N7,N7-tetramethyl-4-((trimethoxysilyl)methyl)heptane-1,7-diamine are particularly preferred. Furthermore, among the compounds satisfying the general formula (xiii), N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethanamine, N,N-bis(trimethylsilyl)-2-(3-(trimethoxysilyl)propoxy)ethanamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethanamine, and N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)propan-1-amine are particularly preferred.

[0058] --Second Preferred Embodiment of Modified Styrene-Butadiene Rubber-- It is also preferable that the styrene-butadiene rubber (SBR) is modified with a coupling agent represented by the following general formula (I). In this case, the fuel economy and wear resistance of a tire to which the rubber composition is applied can be further improved. [ka]

[0059] In the above general formula (I), R 1 , R 2 and R 3 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. R 4 , R 5 , R 6 , R 7 and R 9 each independently represents an alkyl group having 1 to 20 carbon atoms. R 8 and R 11 each independently represents an alkylene group having 1 to 20 carbon atoms. R 10 represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms. m represents an integer of 1 to 3; p represents 1 or 2. R 1 ~R 11 When multiple , m and p are present, they are independent of each other. i, j, and k each independently represent an integer of 0 to 6, provided that (i+j+k) is an integer of 3 to 10. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom and a phosphorus atom and having no active hydrogen. Here, in the general formula (I), the hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the organic group that does not have an active hydrogen include a hydroxyl group (-OH), a secondary amino group (>NH), a primary amino group (-NH 2 ), functional groups having active hydrogen such as sulfhydryl groups (-SH), and organic groups not having active hydrogen.

[0060] The styrene-butadiene rubber modified with the coupling agent represented by the above general formula (I) has a weight average molecular weight (Mw) of 20×10 4 ~300×10 4 The molecular weight of the modified styrene-butadiene rubber is 200×10 4 ~500×10 4 It is preferable that the modified styrene-butadiene rubber contains 0.25 to 30 mass % of the modified styrene-butadiene rubber represented by the formula (I) and has a shrinkage factor (g') of less than 0.64.

[0061] In general, polymers having branches tend to have smaller molecular size compared to linear polymers of the same absolute molecular weight, and the shrinkage factor (g') is an index of the ratio of the molecular size to that of a linear polymer of the same absolute molecular weight. In other words, the larger the degree of branching of a polymer, the smaller the shrinkage factor (g') tends to be. In this embodiment, intrinsic viscosity is used as an index of molecular size, and linear polymers have an intrinsic viscosity [η] = -3.883M 0.771 The shrinkage factor (g') for each absolute molecular weight of the modified styrene-butadiene rubber is calculated, and the shrinkage factor (g') is calculated when the absolute molecular weight is 100 x 10 4 ~200×10 4The average value of the shrinkage factor (g') at this time is the shrinkage factor (g') of the modified styrene-butadiene rubber. Here, "branch" is formed by directly or indirectly bonding one polymer to another polymer. Also, "degree of branching" is the number of polymers that are directly or indirectly bonded to one branch. For example, when five styrene-butadiene copolymer chains described later are bonded to each other indirectly via coupling residues described later, the degree of branching is 5. Note that the coupling residue is a structural unit of the modified styrene-butadiene rubber bonded to the styrene-butadiene copolymer chain, and is, for example, a structural unit derived from a coupling agent that is generated by reacting a styrene-butadiene copolymer described later with a coupling agent. Also, the styrene-butadiene copolymer chain is a structural unit of the modified styrene-butadiene rubber, and is, for example, a structural unit derived from a styrene-butadiene copolymer that is generated by reacting a styrene-butadiene copolymer described later with a coupling agent. The shrinkage factor (g') is preferably less than 0.64, more preferably 0.63 or less, more preferably 0.60 or less, even more preferably 0.59 or less, and even more preferably 0.57 or less. The lower limit of the shrinkage factor (g') is not particularly limited and may be equal to or less than the detection limit, but is preferably 0.30 or more, more preferably 0.33 or more, even more preferably 0.35 or more, and even more preferably 0.45 or more. By using a modified styrene-butadiene rubber having a shrinkage factor (g') in this range, the processability of the rubber composition is improved. Since the shrinkage factor (g') tends to depend on the degree of branching, for example, the shrinkage factor (g') can be controlled using the degree of branching as an index. Specifically, when a modified styrene-butadiene rubber has a degree of branching of 6, its shrinkage factor (g') tends to be 0.59 or more and 0.63 or less, and when a modified styrene-butadiene rubber has a degree of branching of 8, its shrinkage factor (g') tends to be 0.45 or more and 0.59 or less.

[0062] The styrene-butadiene rubber modified by the coupling agent represented by the general formula (I) has branches, and the branching degree is preferably 5 or more. The modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and more preferably, the branching includes a branch in which 5 or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the branching degree is 5 or more and the branching includes a branch in which 5 or more styrene-butadiene copolymer chains are bonded to one coupling residue, the contraction factor (g') can be more reliably made less than 0.64. The number of styrene-butadiene copolymer chains bonded to one coupling residue can be confirmed from the value of the contraction factor (g'). Moreover, the modified styrene-butadiene rubber has branches, and more preferably has a branching degree of 6 or more. Moreover, the modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and further preferably includes a branch in which six or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the branching degree is 6 or more and the branch includes a branch in which six or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be made 0.63 or less. Furthermore, the modified styrene-butadiene rubber has branches, and the branching degree is more preferably 7 or more, and even more preferably 8 or more. The upper limit of the branching degree is not particularly limited, but is preferably 18 or less. The modified styrene-butadiene rubber has one or more coupling residues and a styrene-butadiene copolymer chain bonded to the coupling residue, and further, it is more preferable that the branching includes a branch in which 7 or more styrene-butadiene copolymer chains are bonded to one coupling residue, and it is particularly preferable that the branching includes a branch in which 8 or more styrene-butadiene copolymer chains are bonded to one coupling residue. By specifying the structure of the modified styrene-butadiene rubber so that the branching degree is 8 or more and the branching includes a branch in which 8 or more styrene-butadiene copolymer chains are bonded to one coupling residue, the shrinkage factor (g') can be made 0.59 or less.

[0063] At least one end of the styrene-butadiene copolymer chain is preferably bonded to a silicon atom of each coupling residue. In this case, the ends of a plurality of styrene-butadiene copolymer chains may be bonded to one silicon atom. Alternatively, an end of the styrene-butadiene copolymer chain and an alkoxy group or hydroxyl group having 1 to 20 carbon atoms may be bonded to one silicon atom, and as a result, the one silicon atom may constitute an alkoxysilyl group or silanol group having 1 to 20 carbon atoms.

[0064] The modified styrene-butadiene rubber may be an oil-extended rubber obtained by adding an extender oil. The modified styrene-butadiene rubber may be either non-oil-extended or oil-extended, but from the viewpoint of wear resistance, the Mooney viscosity measured at 100°C is preferably 20 to 100, more preferably 30 to 80.

[0065] The weight average molecular weight (Mw) of the modified styrene-butadiene rubber is preferably 20×10 4 More than 300 x 10 4More preferably, it is 50×10 or less. 4 More preferably, it is 64×10 4 More preferably, it is 80×10 4 The weight average molecular weight is preferably 250×10 4 More preferably, it is 180×10 4 More preferably, it is 150×10 or less. 4 The weight average molecular weight is 20×10 4 When the weight average molecular weight is 300×10 or more, the low loss property and the abrasion resistance of the rubber composition can be sufficiently improved. 4 When it is equal to or less than this, the processability of the rubber composition is improved.

[0066] The modified styrene-butadiene rubber has a molecular weight of 200×10 based on the total amount (100% by mass) of the modified styrene-butadiene rubber. 4 More than 500 x 10 4 It is preferable that the modified styrene-butadiene rubber (hereinafter also referred to as "specific high molecular weight component") is 0.25 mass% or more and 30 mass% or less. When the content of the specific high molecular weight component is 0.25 mass% or more and 30 mass% or less, the low loss property and wear resistance of the rubber composition can be sufficiently improved. The modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 1.0 mass% or more, more preferably at 1.4 mass% or more, even more preferably at 1.75 mass% or more, even more preferably at 2.0 mass% or more, particularly preferably at 2.15 mass% or more, and extremely preferably at 2.5 mass% or more. In addition, the modified styrene-butadiene rubber contains the specific high molecular weight component preferably at 28 mass% or less, more preferably at 25 mass% or less, even more preferably at 20 mass% or less, and even more preferably at 18 mass% or less. In this specification, the "molecular weight" of the rubber component is the standard polystyrene equivalent molecular weight obtained by GPC (gel permeation chromatography). In order to obtain a modified styrene-butadiene rubber having a content of a specific high molecular weight component in such a range, it is preferable to control the reaction conditions in the polymerization step and the reaction step described later. For example, in the polymerization step, the amount of an organic monolithium compound used as a polymerization initiator described later may be adjusted. In addition, in the polymerization step, in both the continuous and batch polymerization modes, a method having a residence time distribution is used, that is, the time distribution of the propagation reaction is expanded.

[0067] In the modified styrene-butadiene rubber, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 1.6 to 3.0. If the molecular weight distribution of the modified styrene-butadiene rubber is in this range, the processability of the rubber composition is good.

[0068] The method for producing the modified styrene-butadiene rubber is not particularly limited, but preferably includes a polymerization step of copolymerizing butadiene and styrene using an organic monolithium compound as a polymerization initiator to obtain a styrene-butadiene copolymer, and a reaction step of reacting an active terminal of the styrene-butadiene copolymer with a pentafunctional or higher reactive compound (hereinafter also referred to as a "coupling agent").

[0069] The polymerization step is preferably a polymerization by a propagation reaction due to a living anionic polymerization reaction, which makes it possible to obtain a styrene-butadiene copolymer having an active terminal and a modified styrene-butadiene rubber with a high modification rate. The styrene-butadiene copolymer is obtained by copolymerizing 1,3-butadiene and styrene.

[0070] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined according to the molecular weight of the target styrene-butadiene copolymer or modified styrene-butadiene rubber. The amount of monomers such as 1,3-butadiene and styrene used relative to the amount of polymerization initiator used is related to the degree of polymerization, that is, the number average molecular weight and / or the weight average molecular weight. Therefore, in order to increase the molecular weight, it is good to adjust the amount of polymerization initiator to decrease, and in order to decrease the molecular weight, it is good to adjust the amount of polymerization initiator to increase. The organic monolithium compound is preferably an alkyllithium compound from the viewpoint of industrial availability and ease of control of the polymerization reaction. In this case, a styrene-butadiene copolymer having an alkyl group at the polymerization initiation terminal is obtained. Examples of the alkyllithium compound include n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoint of industrial availability and ease of control of the polymerization reaction. These organic monolithium compounds may be used alone or in combination of two or more.

[0071] In the polymerization step, examples of the polymerization reaction mode include a batch polymerization mode and a continuous polymerization mode. In the continuous mode, one or more connected reactors can be used. For the continuous mode, for example, a tank type or a tube type reactor equipped with a stirrer is used. In the continuous mode, preferably, a monomer, an inert solvent, and a polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged. For the batch mode, for example, a tank type reactor equipped with a stirrer is used. In the batch mode, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is continuously or intermittently added during polymerization, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is discharged after the polymerization is completed. In this embodiment, in order to obtain a styrene-butadiene copolymer having a high proportion of active ends, a continuous mode is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short time.

[0072] The polymerization step is preferably carried out in an inert solvent. Examples of the solvent include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific examples of the hydrocarbon solvent include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons consisting of mixtures thereof. Before being subjected to the polymerization reaction, impurities such as allenes and acetylenes are treated with an organometallic compound, which tends to obtain a styrene-butadiene copolymer having a high concentration of active ends, and a modified styrene-butadiene rubber with a high modification rate is preferably obtained.

[0073] In the polymerization step, a polar compound may be added. By adding the polar compound, styrene can be randomly copolymerized with 1,3-butadiene, and the polar compound tends to be usable as a vinylizing agent for controlling the microstructure of the 1,3-butadiene portion. Examples of the 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.

[0074] In the polymerization step, from the viewpoint of productivity, the polymerization temperature is preferably 0° C. or higher, more preferably 120° C. or lower, and particularly preferably 50° C. or higher and 100° C. or lower. By keeping the temperature within such a range, there is a tendency that the amount of the coupling agent reacting with the active terminals after the polymerization is completed can be sufficiently ensured.

[0075] The amount of bound butadiene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably from 40% by mass to 100% by mass, and more preferably from 55% by mass to 80% by mass. Furthermore, the amount of bound styrene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably more than 0 mass% and not more than 60 mass%, and more preferably 20 mass% or more and 45 mass% or less. When the bound butadiene amount and the bound styrene amount are within the above ranges, the low loss property and the wear resistance of the rubber composition can be further improved. The amount of bound styrene can be measured by ultraviolet absorption of the phenyl group, from which the amount of bound butadiene can also be calculated.

[0076] In the styrene-butadiene copolymer or modified styrene-butadiene rubber, the amount of vinyl bonds in the butadiene bond units is not particularly limited, but is preferably 10 mol% to 75 mol%, more preferably 20 mol% to 65 mol%. When the amount of vinyl bonds is within the above range, the low loss property and wear resistance of the rubber composition can be further improved. For modified styrene-butadiene rubber, the amount of vinyl bonds (1,2-bonds) in the butadiene bond units can be determined by Hampton's method [RR Hampton, Analytical Chemistry, 21, 923 (1949)].

[0077] The alkoxysilyl group of the coupling agent represented by the above general formula (I) tends to react with, for example, the active terminal of the styrene-butadiene copolymer, dissociating the alkoxylithium, and forming a bond between the end of the styrene-butadiene copolymer chain and the silicon of the coupling residue. The number of alkoxysilyl groups of the coupling residue is the total number of SiO R of one molecule of the coupling agent minus the number of SiO R reduced by the reaction. In addition, the azasilacycle group of the coupling agent forms a >N-Li bond and a bond between the end of the styrene-butadiene copolymer and the silicon of the coupling residue. The >N-Li bond tends to easily become >NH and LiOH due to water or the like during finishing. In addition, the alkoxysilyl group remaining unreacted in the coupling agent tends to easily become a silanol (Si-OH group) due to water or the like during finishing.

[0078] The reaction temperature in the reaction step is preferably the same as the polymerization temperature of the styrene-butadiene copolymer, more preferably from 0° C. to 120° C., and even more preferably from 50° C. to 100° C. The temperature change from the end of the polymerization step to the addition of the coupling agent is preferably 10° C. or less, more preferably 5° C. or less. The reaction time in the reaction step is preferably 10 seconds or more, more preferably 30 seconds or more. From the viewpoint of the coupling rate, the time from the end of the polymerization step to the start of the reaction step is preferably shorter, and more preferably within 5 minutes. The mixing in the reaction step may be performed by mechanical stirring, stirring with a static mixer, or the like. When the polymerization step is a continuous process, it is preferable that the reaction step is also a continuous process. The reactor used in the reaction step may be, for example, a tank type or a tube type equipped with a stirrer. The coupling agent may be diluted with an inert solvent and continuously fed to the reactor. When the polymerization step is a batch process, the coupling agent may be added to the polymerization reactor, or may be transferred to another reactor to carry out the reaction step.

[0079] In the general formula (I), A is preferably represented by any one of the following general formulae (II) to (V). When A is represented by any one of the general formulae (II) to (V), a modified styrene-butadiene rubber having better performance can be obtained.

[0080] [ka] In the general formula (II), B 1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 1 are each independent.

[0081] [ka] In the general formula (III), B 2 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms; B 3 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 2 and B. 3 are each independent.

[0082] [ka] In the general formula (IV), B 4 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 4 are each independent.

[0083] [ka] In the general formula (V), B 5 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. 5 are each independent.

[0084] B in the general formulas (II) to (V) 1 , B 2 , B 4 , B 5 With regard to the above, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkylene group having 1 to 20 carbon atoms.

[0085] Preferably, in the general formula (I), A is represented by the general formula (II) or (III), and k is 0. More preferably, in the general formula (I), A is represented by the general formula (II) or (III), k represents 0, and in the general formula (II) or (III), a represents an integer of 2 to 10. More preferably, in said general formula (I), A is represented by said general formula (II), k represents 0, and in said general formula (II), a represents an integer of 2 to 10. Examples of such coupling agents include bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, and tetrakis(3-trimethoxysilylpropyl). bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine, and the like. Among these, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine and tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane are particularly preferred.

[0086] The amount of the compound represented by the general formula (I) added as the coupling agent can be adjusted so that the mole number of the styrene-butadiene copolymer to the mole number of the coupling agent reacts at a desired stoichiometric ratio, which tends to achieve a desired branching degree. The specific mole number of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, relative to the mole number of the coupling agent. In this case, in the general formula (I), the number of functional groups of the coupling agent ((m-1) x i + p x j + k) is preferably an integer of 5 to 10, more preferably an integer of 6 to 10.

[0087] In order to obtain the modified styrene-butadiene rubber having the specific polymer component, the molecular weight distribution (Mw / Mn) of the styrene-butadiene copolymer is preferably 1.5 to 2.5, more preferably 1.8 to 2.2. The modified styrene-butadiene rubber obtained is preferably one in which a single peak is detected in the molecular weight curve by GPC. The peak molecular weight of the modified styrene-butadiene rubber measured by GPC is Mp 1 , the peak molecular weight of the styrene-butadiene copolymer is Mp 2 In this case, it is preferable that the following formula is satisfied: (Mp 1 / Mp 2 )<1.8×10-12×(Mp 2 -120×10 4 ) 2 +2 Mp 2 is 20 x 10 4 Over 80×10 4 Below, Mp 1 is 30 x 10 4 Over 150 x 10 4 The following is more preferred: 1 and Mp 2 is determined by the method described in the Examples below.

[0088] The modification rate of the modified styrene-butadiene rubber is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. When the modification rate is 30% by mass or more, the low loss property and the wear resistance of the rubber composition can be further improved.

[0089] After the reaction step, a deactivator, neutralizer, etc. may be added to the copolymer solution as necessary. Examples of deactivators include, but are not limited to, water; alcohols such as methanol, ethanol, isopropanol, etc. Examples of neutralizers include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with 10 being the main carbon atom); aqueous solutions of inorganic acids, and carbon dioxide gas. In addition, from the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferable to add an antioxidant such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, or 2-methyl-4,6-bis[(octylthio)methyl]phenol to the modified styrene-butadiene rubber.

[0090] The modified styrene-butadiene rubber can be obtained from the polymer solution by a known method, for example, a method of separating the solvent by steam stripping or the like, filtering the polymer, and then dehydrating and drying the polymer to obtain the polymer, a method of concentrating the polymer in a flashing tank and further devolatilizing the polymer with a vent extruder or the like, and a method of directly devolatilizing the polymer with a drum dryer or the like.

[0091] The modified styrene-butadiene rubber obtained by reacting the coupling agent represented by the above general formula (I) with a styrene-butadiene copolymer is represented, for example, by the following general formula (VI). [ka]

[0092] In the general formula (VI), D represents a styrene-butadiene copolymer chain, and the weight average molecular weight of the styrene-butadiene copolymer chain is 10×10 4 ~100×10 4 The styrene-butadiene copolymer chain is a structural unit of a modified styrene-butadiene rubber, and is, for example, a structural unit derived from a styrene-butadiene copolymer produced by reacting a styrene-butadiene copolymer with a coupling agent. R 12 , R 13 and R 14 each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. R 15 and R 18each independently represents an alkyl group having 1 to 20 carbon atoms. R 16 , R 19 , and R 20 each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. R 17 and R 21 each independently represents an alkylene group having 1 to 20 carbon atoms. R 22 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x each represent an integer of 1 to 3, provided that x≦m; p represents 1 or 2; y represents an integer of 1 to 3, provided that y≦(p+1); and z represents an integer of 1 or 2. D and R when there are multiple 12 ~R 22 , m, p, x, y, and z are each independent and may be the same or different. In addition, i represents an integer from 0 to 6, j represents an integer from 0 to 6, k represents an integer from 0 to 6, (i+j+k) is an integer from 3 to 10, and ((x×i)+(y×j)+(z×k)) is an integer from 5 to 30. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and having no active hydrogen. The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of the organic group having no active hydrogen include a hydroxyl group (-OH), a secondary amino group (>NH), a primary amino group (-NH 2 ), functional groups having active hydrogen such as sulfhydryl groups (-SH), and organic groups not having active hydrogen.

[0093] In the above general formula (VI), A is preferably represented by any one of the above general formulas (II) to (V). When A is represented by any one of the general formulas (II) to (V), the low loss property and wear resistance of the rubber composition can be further improved.

[0094] --Third preferred embodiment of modified styrene-butadiene rubber-- It is also preferable that at least one end of the styrene-butadiene rubber (SBR) is modified with a modifying agent containing a compound (alkoxysilane) represented by the following general formula (1). [ka]

[0095] By using, as the rubber component, a styrene-butadiene rubber modified with a modifier containing a compound represented by the above general formula (1) containing an oligosiloxane and a tertiary amino group, which are filler affinity functional groups, the dispersibility of a filler such as silica can be improved. As a result, the rubber composition of the present invention has improved dispersibility of the filler, and therefore the low loss property is greatly improved, and the rolling resistance of a tire to which the rubber composition is applied can be reduced, thereby improving fuel efficiency.

[0096] In the above general formula (1), R 1 ~R 8 are each independently an alkyl group having 1 to 20 carbon atoms; L 1 and L 2 each independently represents an alkylene group having 1 to 20 carbon atoms; and n is an integer of 2 to 4.

[0097] Specifically, in formula (1), R 1 ~R 4 may each independently be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, 1 ~R 4 When substituted, each independently may be substituted with one or more substituents selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkoxy group having 4 to 10 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an alkanoyloxy group having 2 to 12 carbon atoms (Ra-COO-, where Ra is an alkyl group having 1 to 9 carbon atoms), an aralkyloxy group having 7 to 13 carbon atoms, an arylalkyl group having 7 to 13 carbon atoms, and an alkylaryl group having 7 to 13 carbon atoms. More specifically, the R 1 ~R 4 may be a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and more specifically, 1 ~R 4 may each independently be a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0098] In addition, in formula (1), R 5 ~R 8 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, specifically a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, more specifically a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and when substituted, R 1 ~R 4 It may be substituted with the substituents as described above. In addition, the above R 5 ~R 8 If is not an alkyl group but a hydrolyzable substituent, NR 5 R 6 and N.R. 7 R 8 The bond can be hydrolyzed to NH in the presence of moisture, adversely affecting the processability of the polymer.

[0099] More specifically, in the compound represented by the formula (1), R 1 ~R 4 is a methyl group or an ethyl group, R 5 ~R 8 can be an alkyl group having 1 to 10 carbon atoms.

[0100] The amino group in the compound represented by the formula (1), i.e., NR 5 R 6 and N.R. 7 R 8 is preferably a tertiary amino group. The tertiary amino group provides the compound represented by formula (1) with better processability when used as a modifying agent. In addition, the above R 5 ~R 8When a protecting group for protecting the amino group is bonded to the end of the polymer or when hydrogen is bonded to the end of the polymer, it may be difficult to realize the effect of the compound represented by formula (1). When hydrogen is bonded, the anion reacts with hydrogen during the modification process and loses reactivity, making the modification reaction itself impossible, and when a protecting group is bonded, the modification reaction takes place, but in the state bonded to the polymer end, it is deprotected by hydrolysis during post-processing to become a primary or secondary amino group, and the deprotected primary or secondary amino group may cause the compound to become highly viscous during subsequent blending, which may cause a decrease in processability.

[0101] In addition, L in the compound represented by the formula (1) 1 and L 2 each independently represents a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. More specifically, L 1 and L 2 may each independently be an alkylene group having 1 to 10 carbon atoms, more specifically, an alkylene group having 1 to 6 carbon atoms, such as a methylene group, an ethylene group, or a propylene group.

[0102] L in the compound represented by formula (1) 1 and L 2 The shorter the distance between the Si atom and the N atom in the molecule, the better the effect. However, when Si is directly bonded to N, there is a risk that the bond between Si and N may break during the subsequent processing steps, and the secondary amino group generated at this time is likely to be washed away by water during the post-processing, and in the modified styrene-butadiene rubber produced, it is difficult for the amino group, which promotes bonding with fillers such as silica, to bond with the filler, and as a result, the effect of improving the dispersibility of the filler may be reduced. Considering the improvement effect due to the length of the bond between Si and N, the above L 1 and L 2 More preferably, each independently represents an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and more specifically, can be a propylene group. 1 and L 2 R first 1 ~R4 It may be substituted with the substituents as described above.

[0103] The compound represented by the formula (1) is preferably, for example, any one of the compounds represented by the following structural formulas (1-1) to (1-5), because this allows for more excellent low loss properties to be achieved. [ka]

[0104] The compound represented by the formula (1) has an alkoxysilane structure that bonds with the active end of the styrene-butadiene copolymer, while the Si-O-Si structure and three or more amino groups bonded to the end show affinity for fillers such as silica, and thus can promote the bonding between the filler and the modified styrene-butadiene rubber compared to conventional modifiers containing one amino group in the molecule. In addition, the degree of bonding of the active end of the styrene-butadiene copolymer is uniform, and when the change in molecular weight distribution before and after coupling is observed, the molecular weight distribution after coupling is not larger than before and remains constant. Therefore, there is no deterioration in the physical properties of the modified styrene-butadiene rubber itself, and the aggregation of the filler in the rubber composition can be prevented, and the dispersibility of the filler can be increased, thereby improving the processability of the rubber composition. These effects make it possible to improve the fuel efficiency and wet grip performance in a well-balanced manner, particularly when the rubber composition is applied to tires.

[0105] The compound represented by the formula (1) can be produced through a condensation reaction represented by the following reaction scheme. [ka]

[0106] In the above reaction scheme, R 1 ~R 8 , L 1 and L 2and n are the same as those defined in the above formula (1), and R′ and R″ are any substituents that do not affect the condensation reaction. For example, R′ and R″ are each independently R 1 ~R 4 may be identical to any one of the following:

[0107] The reaction of the reaction scheme proceeds in the presence of an acid, and the acid can be any acid that is generally used in condensation reactions without limitation. Those skilled in the art can select an optimal acid depending on various process variables such as the type of reactor in which the reaction is carried out, starting materials, reaction temperature, etc.

[0108] The styrene-butadiene rubber modified by the modifier containing the compound represented by formula (1) can have a narrow molecular weight distribution (Mw / Mn, also referred to as "polydispersity index (PDI)") of 1.1 to 3.0. If the molecular weight distribution of the modified styrene-butadiene rubber exceeds 3.0 or is less than 1.1, the tensile properties and viscoelasticity may be reduced when applied to a rubber composition. Considering the remarkable effect of improving the tensile properties and viscoelasticity by controlling the molecular weight distribution of the modified styrene-butadiene rubber, the molecular weight distribution of the modified styrene-butadiene rubber is preferably in the range of 1.3 to 2.0. By using the modifier, the modified styrene-butadiene rubber has a molecular weight distribution similar to that of the styrene-butadiene copolymer before modification.

[0109] The molecular weight distribution of the modified styrene-butadiene rubber can be calculated from the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn). In this case, the number average molecular weight (Mn) is the common average of the molecular weights of individual polymers calculated by measuring the molecular weights of n polymer molecules, calculating the sum of these molecular weights, and dividing by n, and the weight average molecular weight (Mw) represents the molecular weight distribution of a polymer composition. The average of the total molecular weight can be expressed in grams per mole (g / mol). The weight average molecular weight and number average molecular weight are each a polystyrene-equivalent molecular weight analyzed by gel permeation chromatography (GPC).

[0110] The modified styrene-butadiene rubber satisfies the above-mentioned molecular weight distribution conditions, and may have a number average molecular weight (Mn) of 50,000 g / mol to 2,000,000 g / mol, more specifically, 200,000 g / mol to 800,000 g / mol. The modified styrene-butadiene rubber may have a weight average molecular weight (Mw) of 100,000 g / mol to 4,000,000 g / mol, more specifically, 300,000 g / mol to 1,500,000 g / mol. When the weight average molecular weight (Mw) of the modified styrene-butadiene rubber is less than 100,000 g / mol or the number average molecular weight (Mn) is less than 50,000 g / mol, the tensile properties may be deteriorated when applied to a rubber composition. When the weight average molecular weight (Mw) is more than 4,000,000 g / mol or the number average molecular weight (Mn) is more than 2,000,000 g / mol, the processability of the modified styrene-butadiene rubber is deteriorated, the workability of the rubber composition is deteriorated, kneading becomes difficult, and it may be difficult to sufficiently improve the physical properties of the rubber composition. More specifically, when the modified styrene-butadiene rubber satisfies the conditions of weight average molecular weight (Mw) and number average molecular weight (Mn) as well as the molecular weight distribution, when it is applied to a rubber composition, it can improve the viscoelasticity and processability of the rubber composition in a well-balanced manner.

[0111] The modified styrene-butadiene rubber has a vinyl bond content in the butadiene portion of preferably 5% or more, more preferably 10% or more, and more preferably 60% or less. By setting the vinyl bond content in the butadiene portion within the above range, the glass transition temperature can be adjusted to an appropriate range.

[0112] The modified styrene-butadiene rubber may have a Mooney viscosity (MV) at 100° C. of 40 to 140, specifically 60 to 100. When the modified styrene-butadiene rubber has a Mooney viscosity in the above range, it can exhibit better processability. The Mooney viscosity can be measured using a Mooney viscometer, for example, Monsanto's MV2000E, with a large rotor at 100° C. and a rotor speed of 2±0.02 rpm. The sample used here is left at room temperature (23±3° C.) for 30 minutes or more, and then 27±3 g of the sample is taken and filled into the die cavity, and the platen is operated to measure.

[0113] As described above, the modified styrene-butadiene rubber is preferably modified at one end with a modifier containing a compound represented by the above general formula (1), and is preferably further modified at the other end with a modifier containing a compound represented by the following general formula (2). By modifying both ends of the modified styrene-butadiene rubber, the dispersibility of the filler in the rubber composition is further improved, and a tire to which the rubber composition is applied can achieve both low fuel consumption performance and wet grip performance at a higher level. [ka]

[0114] In the above general formula (2), R 9 ~R 11 are each independently hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms, a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms. In addition, in formula (2), R 12 represents a single bond; an alkylene group having 1 to 20 carbon atoms which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms which is substituted or unsubstituted; or an arylene group having 5 to 20 carbon atoms which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. In addition, in formula (2), R 13is an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; a heterocyclic group having 3 to 30 carbon atoms; or a functional group represented by the following general formula (2a) or general formula (2b), m is an integer of 1 to 5, R 13 At least one of the functional groups represented by the following general formula (2a) or (2b) is a functional group represented by the following general formula (2a) or (2b). When m is an integer of 2 to 5, a plurality of R 13 may be the same or different from each other.

[0115] [ka]

[0116] In the above general formula (2a), R 14 represents an alkylene group having 1 to 20 carbon atoms, which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms, which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms, which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. In addition, in formula (2a), R 15 and R 16 are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an alkylene group having 1 to 20 carbon atoms which is unsubstituted or substituted with an aryl group having 6 to 20 carbon atoms. In addition, in formula (2a), R 17 is hydrogen; an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms; and X is an N, O or S atom, provided that when X is O or S, R 17 does not exist.

[0117] [ka]

[0118] In the above general formula (2b), R 18 represents an alkylene group having 1 to 20 carbon atoms, which is substituted or unsubstituted; a cycloalkylene group having 5 to 20 carbon atoms, which is substituted or unsubstituted; or an arylene group having 6 to 20 carbon atoms, which is substituted or unsubstituted, wherein the substituent is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. In addition, in formula (2b), R 19 and R 20 are each independently an alkyl group having 1 to 30 carbon atoms; an alkenyl group having 2 to 30 carbon atoms; an alkynyl group having 2 to 30 carbon atoms; a heteroalkyl group having 1 to 30 carbon atoms; a heteroalkenyl group having 2 to 30 carbon atoms; a heteroalkynyl group having 2 to 30 carbon atoms; a cycloalkyl group having 5 to 30 carbon atoms; an aryl group having 6 to 30 carbon atoms; or a heterocyclic group having 3 to 30 carbon atoms.

[0119] In addition, in the compound represented by the above general formula (2), R 9 ~R 11 are each independently hydrogen; an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; or an alkynyl group having 2 to 10 carbon atoms; R 12 is a single bond; or an unsubstituted alkylene group having 1 to 10 carbon atoms, R 13 is an alkyl group having 1 to 10 carbon atoms; an alkenyl group having 2 to 10 carbon atoms; an alkynyl group having 2 to 10 carbon atoms; or a functional group represented by the above general formula (2a) or general formula (2b), and in the above general formula (2a), R 14 is an unsubstituted alkylene group having 1 to 10 carbon atoms, R 15 and R 16 are each independently an unsubstituted alkylene group having 1 to 10 carbon atoms, and R 17is an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms, and in the above general formula (2b), R 18 is an unsubstituted alkylene group having 1 to 10 carbon atoms, R 19 and R 20 may each independently be an alkyl group having 1 to 10 carbon atoms; a cycloalkyl group having 5 to 20 carbon atoms; an aryl group having 6 to 20 carbon atoms; or a heterocyclic group having 3 to 20 carbon atoms.

[0120] More specifically, the compound represented by the above general formula (2) can be the compounds represented by the following structural formulas (2-1) to (2-3). [ka]

[0121] In addition, when the styrene-butadiene copolymer is modified with a modifying agent containing the compound represented by the above general formula (2), the modifying agent containing the compound represented by formula (2) is used as a modification initiator. Specifically, for example, a butadiene monomer and a styrene monomer are polymerized in a hydrocarbon solvent in the presence of a modifying agent containing a compound represented by formula (2), thereby imparting a modifying group derived from the compound represented by formula (2) to the styrene-butadiene copolymer.

[0122] -Other rubber- The rubber component may further contain other rubbers, and the content of the other rubbers in 100 parts by mass of the rubber component is preferably 35 parts by mass or less. Examples of such other rubbers include styrene-butadiene rubber, butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene rubber (EPR, EPDM), fluororubber, silicone rubber, and urethane rubber, each of which has a glass transition temperature of -40°C or higher. Among these, diene rubbers such as butadiene rubber (BR) and chloroprene rubber (CR) are preferred, and butadiene rubber (BR) is more preferred. As the butadiene rubber (BR), high-cis polybutadiene is preferable, and the high-cis polybutadiene preferably has a cis-1,4 bond content of 90% by mass or more. When the rubber component contains butadiene rubber, the content of the butadiene rubber is preferably in the range of 1 to 35 parts by mass in 100 parts by mass of the rubber component.

[0123] (Resin component) The rubber composition for tires of this embodiment contains a resin component, and the resin component is at least partially hydrogenated. By at least partially hydrogenating the resin component, the compatibility with isoprene skeleton rubber is increased, the mobility of the rubber component is controlled, and the hysteresis loss (tan δ) in the low temperature range can be improved, so that the wet grip performance of a tire to which the rubber composition is applied is improved.

[0124] The resin component has an SP value difference of 1.40 (cal / cm) from the isoprene skeleton rubber. 3 ) 1 / 2 The difference in SP value between the resin component and the isoprene skeleton rubber is preferably 1.40 (cal / cm 3 ) 1 / 2 When the rubber composition is used in a tire having a rubber composition having a molecular weight of 100 or less, the compatibility with the isoprene skeleton rubber is further increased, the mobility of the rubber component is further controlled, and the hysteresis loss (tan δ) in the low temperature region can be further improved, thereby further improving the wet grip performance of a tire to which the rubber composition is applied. From the viewpoint of further improving compatibility, the difference in SP value between the resin component and the isoprene skeleton rubber is set to 1.35 (cal / cm 3 ) 1 / 2 It is preferable that the calorie content is 0.50 (cal / cm 3 ) 1 / 2 More preferably, it is 0.45 (cal / cm 3 ) 1 / 2 More preferably, it is 0.3 (cal / cm 3 ) 1 / 2 More preferably, it is 0.25 (cal / cm 3 ) 1 / 2It is more preferable that the difference in SP value between the resin component and the isoprene skeleton rubber is 0.50 (cal / cm 3 ) 1 / 2 When the content is equal to or less than this, the compatibility between the resin component and the isoprene skeleton rubber is further improved, and the wet grip performance of a tire to which the rubber composition is applied is further improved.

[0125] The content of the resin component is 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the rubber component. When the content of the resin component in the rubber composition is 1 part by mass or more per 100 parts by mass of the rubber component, the effect of the resin component is fully expressed, and when it is less than 50 parts by mass, the resin component is less likely to precipitate from the tire, and the effect of the resin component can be fully expressed. On the other hand, when the content of the resin component is 50 parts by mass or more per 100 parts by mass of the rubber component, the fracture resistance of the rubber composition is deteriorated, and the fuel efficiency and wear resistance of the tire to which the rubber composition is applied are deteriorated. From the viewpoint of further enhancing the effect of the resin component, the content of the resin component in the rubber composition is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, more preferably 9 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 17 parts by mass or more per 100 parts by mass of the rubber component. From the viewpoint of suppressing precipitation of the resin component from the tire and suppressing deterioration in the appearance of the tire, the content of the resin component in the rubber composition is more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the rubber component.

[0126] The resin component preferably has a softening point higher than 110° C. and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol. By applying a rubber composition containing such a resin component to a tire, the wear resistance of the tire can be further improved. Here, the softening point of the resin component is measured in accordance with JIS-K2207-1996 (ring and ball method). The weight average molecular weight of the resin component is measured by gel permeation chromatography (GPC) and calculated as a polystyrene equivalent value.

[0127] When the softening point of the resin component is higher than 110° C., the tire to which the rubber composition is applied can be sufficiently reinforced, and the wear resistance can be further improved. From the viewpoint of the wear resistance of the tire, the softening point of the resin component is preferably 116° C. or higher, more preferably 120° C. or higher, more preferably 123° C. or higher, and even more preferably 127° C. or higher. From the viewpoint of processability, the softening point of the resin component is preferably 160° C. or lower, more preferably 150° C. or lower, more preferably 145° C. or lower, more preferably 141° C. or lower, and even more preferably 136° C. or lower.

[0128] When the weight average molecular weight of the resin component in terms of polystyrene is 200 g / mol or more, the resin component is less likely to precipitate from the tire and the effects of the resin component can be fully exhibited, and when it is 1600 g / mol or less, the resin component is easily compatible with the rubber component. From the viewpoints of suppressing precipitation of the resin component from the tire and suppressing deterioration in the appearance of the tire, the polystyrene-equivalent weight average molecular weight of the resin component is preferably 500 g / mol or more, more preferably 550 g / mol or more, more preferably 600 g / mol or more, still more preferably 650 g / mol or more, and even more preferably 700 g / mol or more. In addition, from the viewpoint of improving the compatibility of the resin component with the rubber component and further enhancing the effect of the resin component, the polystyrene-equivalent weight average molecular weight of the resin component is more preferably 1570 g / mol or less, more preferably 1530 g / mol or less, more preferably 1500 g / mol or less, more preferably 1470 g / mol or less, more preferably 1430 g / mol or less, more preferably 1400 g / mol or less, more preferably 1370 g / mol or less, more preferably 1330 g / mol or less, more preferably 1300 g / mol or less, more preferably 1200 g / mol or less, more preferably 1100 g / mol or less, more preferably 1000 g / mol or less, and even more preferably 950 g / mol or less. When the polystyrene-equivalent weight average molecular weight of the resin component is 200 to 1200 g / mol, the resin component is less likely to precipitate from the tire, and the resin component is more easily compatible with the rubber component, making the effects of the resin component more pronounced.

[0129] The weight average molecular weight (Mw HR ) (unit: g / mol) vs. the softening point of the resin component (Ts HR ) (unit: °C) ratio (Ts HR / Mw HR ) is preferably 0.07 or more, more preferably 0.083 or more, more preferably 0.095 or more, more preferably 0.104 or more, more preferably 0.125 or more, more preferably 0.135 or more, more preferably 0.14 or more, and even more preferably 0.141 or more. HR / Mw HR) is preferably 0.25 or less, more preferably 0.24 or less, more preferably 0.23 or less, more preferably 0.19 or less, more preferably 0.18 or less, and even more preferably 0.17 or less.

[0130] The above-mentioned at least partially hydrogenated resin component means a resin obtained by reducing and hydrogenating a resin. The resins that are the raw materials for the hydrogenated resin components are C 5 based resin, C 5 -C 9 based resin, C 9 These resins may be used alone or in combination of two or more.

[0131] Said C 5 As for the resin, C is obtained by thermal cracking of naphtha in the petrochemical industry. 5 Examples of such resins include aliphatic petroleum resins obtained by (co)polymerizing the fraction. C 5 The fraction usually contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. 5 The resin may be a commercially available product.

[0132] Said C 5 -C 9 The resin is C 5 -C 9 C refers to synthetic petroleum resin. 5 -C 9 As a type of resin, for example, petroleum-derived C 5 -C 11 The fraction was dissolved in AlCl 3 , B.F. 3More specifically, copolymers containing styrene, vinyl toluene, α-methyl styrene, indene, or the like as a main component can be mentioned. C 5 -C 9 As for the resin, 9 Resins containing less of the above components are preferred from the viewpoint of compatibility with the rubber component. 9 "Less than 100% of the total resin content" means that 9 This means that the above components are less than 50% by mass, preferably 40% by mass or less. 5 -C 9 The resin may be a commercially available product.

[0133] Said C 9 The resin is C 9 This refers to synthetic petroleum resins, such as AlCl 3 Or BF 3 Using Friedel-Crafts type catalysts such as C 9 It refers to a solid polymer obtained by polymerizing a fraction. C 9 Examples of the resin include copolymers containing indene, α-methylstyrene, vinyltoluene, or the like as a main component.

[0134] The terpene resin is a solid resin obtained by blending turpentine obtained at the same time when rosin is obtained from pine trees, or a polymerization component separated from the turpentine, and polymerizing the blend using a Friedel-Crafts catalyst, and examples of the terpene resin include β-pinene resin and α-pinene resin. A representative example of the terpene-aromatic compound resin is terpene-phenol resin. This terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing the terpene with formalin. There is no particular restriction on the terpene as the raw material, and monoterpene hydrocarbons such as α-pinene and limonene are preferred, and those containing α-pinene are more preferred, with α-pinene being particularly preferred. Styrene and the like may be included in the skeleton.

[0135] The dicyclopentadiene resin is, for example, AlCl 3 Or BF 3 This refers to a resin obtained by polymerizing dicyclopentadiene using a Friedel-Crafts type catalyst such as

[0136] The resin that is the raw material for the hydrogenated resin component is, for example, C 5 Resin (C) copolymerized with the fraction and dicyclopentadiene (DCPD) 5 -DCPD-based resin). Here, when the dicyclopentadiene-derived component in the total amount of the resin is 50 mass% or more, C 5 -DCPD resins are included in dicyclopentadiene resins. If the dicyclopentadiene-derived component in the total amount of resin is less than 50 mass%, 5 -DCPD resin is C 5 The same applies to cases where a small amount of a third component is contained.

[0137] From the viewpoints of increasing the compatibility between the rubber component and the resin component, further improving the wet grip performance of a tire to which the rubber composition is applied, and further reducing the rolling resistance, the resin component is 5 based resin, hydrogenated C 5 -C 9 It is preferable that the resin is at least one selected from the group consisting of hydrogenated C-type resins, hydrogenated dicyclopentadiene-type resins (hydrogenated DCPD-type resins), and hydrogenated terpene-type resins. 5 Resin and hydrogenated C 5 -C 9 More preferably, the resin is at least one selected from the group consisting of hydrogenated C 5 It is more preferable that the resin component is a hydrogenated DCPD-based resin. It is also preferable that the resin component is a resin having at least a hydrogenated DCPD structure or a hydrogenated cyclic structure in the monomer. 5 based resin, hydrogenated C 5 -C 9When the rubber composition is at least one selected from the group consisting of a cyclopentadiene-based resin, a hydrogenated dicyclopentadiene-based resin, and a hydrogenated terpene-based resin, the wet grip performance of a tire to which the rubber composition is applied can be further improved and the rolling resistance can be further reduced.

[0138] (Filler) The rubber composition for a tire according to the present embodiment contains a filler. By containing the filler, the reinforcing property of the rubber composition is improved. The content of the filler in the rubber composition is preferably in the range of 40 to 125 parts by mass relative to 100 parts by mass of the rubber component. When the content of the filler in the rubber composition is 40 parts by mass or more relative to 100 parts by mass of the rubber component, the reinforcement of the tire to which the rubber composition is applied is sufficient, and the fracture resistance and abrasion resistance can be further improved. When the content of the filler in the rubber composition is 125 parts by mass or less, the elastic modulus of the rubber composition does not become too high, and the wet grip performance of the tire to which the rubber composition is applied is further improved. From the viewpoint of lowering the rolling resistance of the tire (from the viewpoint of improving fuel efficiency performance), the content of the filler in the rubber composition is more preferably 45 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more relative to 100 parts by mass of the rubber component. In addition, from the viewpoint of improving the wet grip performance of the tire, the content of the filler in the rubber composition is more preferably 105 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 95 parts by mass or less relative to 100 parts by mass of the rubber component.

[0139] -silica- The filler preferably contains silica and has a nitrogen adsorption specific surface area (BET method) of 80 m 2 / g or more 330m 2 It is more preferable that the silica contains silica having a nitrogen adsorption specific surface area (BET method) of less than 80 m 2 When the rubber composition is used in a tire, the tire can be sufficiently reinforced and the rolling resistance of the tire can be further reduced. 2When the silica has a nitrogen adsorption specific surface area (BET method) of 110 m / g or less, the elastic modulus of the rubber composition is not too high, and the wet grip performance of a tire using the rubber composition is further improved. 2 / g or more, and 2 / g or more, and 150m 2 / g or more, and 2 From the viewpoint of further improving the wet grip performance of the tire, the nitrogen adsorption specific surface area (BET method) of the silica is preferably 300 m 2 / g or less, and 2 / g or less is more preferable, and 2 It is more preferable that the molecular weight is not more than 1 / g.

[0140] Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc., and among these, wet silica is preferred. These silicas may be used alone or in combination of two or more.

[0141] The silica is also preferably plant-derived silica. The silica derived from the plant is preferably silica derived from a silicic acid plant from the viewpoint of reducing environmental load. The silicic acid plant is present in, for example, moss, ferns, horsetails, Cucurbitaceae, Urticaceae, and Gramineae plants. Among these plants, Gramineae plants are preferred, that is, the silica derived from the plant is preferably silica derived from a Gramineae plant. Gramineae-derived silica can be procured locally as raw material near a tire manufacturing plant, and therefore can reduce energy and costs for transportation and storage, which is environmentally preferable from various viewpoints. Examples of the Gramineae plant include rice, bamboo grass, sugarcane, etc., and among these, rice is preferred. Rice is widely cultivated for food, so it can be procured locally in a wide area, and rice husks are generated in large quantities as industrial waste, so it is easy to secure the amount. Therefore, from the viewpoint of availability, silica derived from rice husks (hereinafter also referred to as "rice husk silica") is particularly preferred as plant-derived silica. By using the rice husk silica, rice husks that become industrial waste can be effectively utilized, and since the raw material can be procured locally near the tire manufacturing plant, the energy and cost of transportation and storage can be reduced, which is environmentally preferable from various viewpoints. The rice husk silica may be a powder of rice husk charcoal obtained by carbonizing rice husks by heating, or may be precipitated silica produced by a wet method using an alkali silicate aqueous solution prepared by extracting rice husk ash generated when rice husks are burned as fuel in a biomass boiler with an alkali to prepare an alkali silicate aqueous solution. The method for producing the rice husk charcoal is not particularly limited, and various known methods can be used. For example, rice husk charcoal can be obtained by pyrolyzing the rice husks by steaming them in a kiln. The rice husk charcoal thus obtained is pulverized using a known pulverizer (for example, a ball mill), and then sorted and classified into a predetermined particle size range to obtain rice husk charcoal powder. In addition, the rice husk-derived precipitated silica can be produced by the method described in JP 2019-38728 A.

[0142] From the viewpoint of improving the mechanical strength of the tire and further improving the fracture resistance and abrasion resistance, the content of silica in the rubber composition is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more, relative to 100 parts by mass of the rubber component. Also, from the viewpoint of further improving the wet grip performance of the tire, the content of silica in the rubber composition is preferably 125 parts by mass or less, more preferably 105 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 95 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0143] -Carbon black- The filler preferably contains carbon black, which reinforces the rubber composition and improves the fracture resistance and abrasion resistance of the rubber composition. The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more. The carbon black may also be recycled carbon black.

[0144] In this specification, "recycled carbon black" refers to carbon black obtained by recovering from raw materials that are waste materials that have been subjected to recycling. Examples of the waste materials that have been subjected to recycling include rubber products (particularly vulcanized rubber products) that contain carbon black, such as used rubber and used tires, and waste oil. "Recycled carbon black" is different from carbon black that is produced directly from raw materials such as hydrocarbons, such as petroleum and natural gas, that is, carbon black that is not recycled. Note that "used" here includes not only carbon black that has been actually used and then discarded, but also carbon black that has been produced but discarded without actually being used.

[0145] From the viewpoint of improving the fracture resistance and abrasion resistance of the rubber composition and a tire using the same, the content of carbon black in the rubber composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. Also, from the viewpoint of workability of the rubber composition, the content of carbon black in the rubber composition is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the filler contains silica and carbon black, the proportion of silica in the total amount of silica and carbon black is preferably 80% by mass or more and less than 100% by mass, and more preferably 90% by mass or more and less than 100% by mass. When the proportion of silica is 80% by mass or more, the mechanical strength of a tire to which the rubber composition is applied is improved, and the rolling resistance can be further reduced.

[0146] -Other fillers- The filler may include inorganic fillers such as clay, talc, calcium carbonate, and aluminum hydroxide, in addition to silica and carbon black. The above-mentioned other fillers are preferably contained in such a range that the ratio of silica in the filler is 70% by mass or more. By making the ratio of silica in the filler 70% by mass or more, the mechanical strength of the tire to which the rubber composition is applied is improved, and the rolling resistance can be further reduced. The ratio of silica in the filler is more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more and less than 100% by mass.

[0147] (oil) The rubber composition for a tire of this embodiment may or may not contain oil; that is, in the rubber composition for a tire of this embodiment, oil is not an essential component but an optional component.

[0148] The oil is a general term for the extender oil contained in the rubber component and the liquid oil [more specifically, liquid at 25°C (room temperature)] added as a compounding agent to the rubber composition, and includes petroleum oils such as aromatic oils, paraffinic oils, naphthenic oils, etc.; and vegetable oils such as palm oil, castor oil, cottonseed oil, soybean oil, etc. Among these, petroleum oils such as aromatic oils, paraffinic oils, naphthenic oils, etc. are preferred.

[0149] The content of the oil may be 0 parts by mass (i.e., 0 parts by mass or more) relative to 100 parts by mass of the rubber component, and is preferably 1 part by mass or more, more preferably 2.5 parts by mass or more, and also preferably 5 parts by mass or less, and more preferably 3 parts by mass or less. When the content of the oil is 2.5 parts by mass or more relative to 100 parts by mass of the rubber component, the unvulcanized viscosity of the rubber composition is further reduced, and the workability in kneading is further improved. In addition, when the content of the oil is 3 parts by mass or less relative to 100 parts by mass of the rubber component, the fracture resistance of the rubber composition can be more reliably maintained.

[0150] The difference between the number of parts by mass of the resin component (i.e., the content (parts by mass) of the resin component per 100 parts by mass of the rubber component) and the number of parts by mass of the oil (i.e., the content (parts by mass) of the oil per 100 parts by mass of the rubber component) (number of parts by mass of resin component-number of parts by mass of oil) is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less. When [number of parts by mass of resin component-number of parts by mass of oil] is 20 parts by mass or more, the fracture resistance performance can be maintained, and when [number of parts by mass of resin component-number of parts by mass of oil] is 40 parts by mass or less, the workability in kneading can be improved.

[0151] (Relationship between resin component, oil, and isoprene-based rubber mass parts) The rubber composition for a tire according to the present embodiment has the following formula (1): 0.70≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene-skeleton rubber≦1.18 (1) The above relationship is satisfied. Here, "parts by mass of resin component" refers to the amount (parts by mass) of resin component per 100 parts by mass of rubber component, "parts by mass of oil" refers to the amount (parts by mass) of oil per 100 parts by mass of rubber component, and "parts by mass of isoprene skeleton rubber" refers to the amount (parts by mass) of isoprene skeleton rubber in 100 parts by mass of rubber component. If the [(parts by mass of resin component-parts by mass of oil) / parts by mass of isoprene skeleton rubber] is less than 0.70, the fracture resistance of the rubber composition is significantly deteriorated. Also, if the [(parts by mass of resin component-parts by mass of oil) / parts by mass of isoprene skeleton rubber] exceeds 1.18, the fracture resistance of the rubber composition is deteriorated. From the viewpoint of the fracture resistance of the rubber composition, [(parts by mass of resin component-parts by mass of oil) / parts by mass of isoprene skeleton rubber] is preferably 0.71 or more, more preferably 0.79 or more, and is preferably 1.18 or less, and more preferably 1.00 or less. Also, the rubber composition for tires of this embodiment has the following formula (1'): 0.79≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene-skeleton rubber≦1.00 (1′) It is particularly preferable that the following relationship is satisfied: The rubber composition that satisfies the relationship of formula (1') more reliably maintains the fracture resistance.

[0152] (styrene-based thermoplastic elastomer) The rubber composition for tires of this embodiment may contain a styrene-based thermoplastic elastomer (TPS). The styrene-based thermoplastic elastomer (TPS) has a styrene-based polymer block (hard segment) and a conjugated diene-based polymer block (soft segment), and the styrene-based polymer portion forms a physical crosslink to become a crosslinking point, while the conjugated diene-based polymer block imparts rubber elasticity. The double bonds of the conjugated diene-based polymer block (soft segment) may be partially or completely hydrogenated. In addition, the styrene-based thermoplastic elastomer (TPS) is thermoplastic, whereas the rubber component (preferably, diene-based rubber) is not thermoplastic. Therefore, in this specification, the styrene-based thermoplastic elastomer (TPS) is not included in the rubber component. The content of the styrene-based thermoplastic elastomer (TPS) is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

[0153] Examples of the styrene-based thermoplastic elastomer (TPS) include styrene / butadiene / styrene (SBS) block copolymers, styrene / isoprene / styrene (SIS) block copolymers, styrene / butadiene / isoprene / styrene (SBIS) block copolymers, styrene / butadiene (SB) block copolymers, styrene / isoprene (SI) block copolymers, styrene / butadiene / isoprene (SBI) block copolymers, styrene / ethylene / butylene / styrene (SEBS) block copolymers, styrene / ethylene / propylene / styrene (SEPS) block copolymers, styrene / ethylene / ethylene / propylene / styrene (SEEPS) block copolymers, styrene / ethylene / butylene (SEB) block copolymers, styrene / ethylene / propylene (SEP) block copolymers, and styrene / ethylene / ethylene / propylene (SEEP) block copolymers.

[0154] (others) The rubber composition for tires of this embodiment may contain the above-mentioned rubber component, resin component, filler, oil, and styrene-based thermoplastic elastomer, as well as various components commonly used in the rubber industry, such as silane coupling agents, antioxidants, waxes, processing aids, stearic acid, zinc oxide (zinc oxide), vulcanization accelerators, vulcanizing agents, etc., as necessary, appropriately selected within the range not impairing the object of the present invention. Commercially available products can be suitably used as these compounding agents.

[0155] When the rubber composition for tires of the present embodiment contains silica, it is preferable to contain a silane coupling agent in order to improve the effect of the silica. Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, Examples of the silane coupling agent include N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide. The content of the silane coupling agent is preferably in the range of 2 to 20 parts by mass, more preferably in the range of 5 to 15 parts by mass, relative to 100 parts by mass of the silica.

[0156] Examples of the antiaging agent include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6C), 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), N,N'-diphenyl-p-phenylenediamine (DPPD), etc. The content of the antiaging agent is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, more preferably 1 to 4 parts by mass, based on 100 parts by mass of the rubber component.

[0157] Examples of the wax include paraffin wax, microcrystalline wax, etc. The content of the wax is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, and more preferably 1 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0158] The content of the zinc oxide (zinc white) is not particularly limited, and is preferably in the range of 0.1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the rubber component.

[0159] Examples of the vulcanization accelerator include sulfenamide vulcanization accelerators, guanidine vulcanization accelerators, thiazole vulcanization accelerators, thiuram vulcanization accelerators, and dithiocarbamate vulcanization accelerators. These vulcanization accelerators may be used alone or in combination of two or more. The content of the vulcanization accelerator is not particularly limited, and is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 0.2 to 4 parts by mass, based on 100 parts by mass of the rubber component.

[0160] The vulcanizing agent may be sulfur, etc. The content of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by mass, more preferably 1 to 4 parts by mass, in terms of sulfur content, per 100 parts by mass of the rubber component.

[0161] (Method of manufacturing rubber composition for tires) The method for producing the rubber composition is not particularly limited, but for example, the rubber composition can be produced by blending various components appropriately selected as necessary with the above-mentioned rubber component, resin component, and filler, and kneading, heating, extruding, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0162] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0163] The conditions of the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, heat-in equipment, etc. can be appropriately selected depending on the purpose. Examples of the heat-in equipment include a heat-in roller machine usually used for heat-in of a rubber composition.

[0164] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder that is usually used for extruding a rubber composition. The extrusion temperature can be appropriately determined.

[0165] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected according to the purpose. As the vulcanization apparatus, a molding vulcanizer using a mold used for vulcanizing a rubber composition can be mentioned. As the vulcanization condition, the temperature is, for example, about 100 to 190°C.

[0166] (Application) The rubber composition for tires of this embodiment can be applied to various components of tires, for example, treads (cap tread, base tread, under tread), cushion rubber, shoulders, side rubber, clinches, bead fillers, carcass coating rubber, insulation, chafers, inner liners, etc., and can also be used for side reinforcing layers of run-flat tires, etc. In addition to tires, the rubber composition for tires of this embodiment can also be applied to rubber crawlers, seismic isolation rubber, etc. Among these, the rubber composition for tires of this embodiment is suitable for use as tire tread rubber.

[0167] <Tire tread rubber> The tire tread rubber of this embodiment is characterized by being made of the above-mentioned rubber composition for tires of this embodiment. Since the tire tread rubber of this embodiment is made of the above-mentioned rubber composition for tires, the workability in production is improved while maintaining the fracture resistance. The tire tread rubber of this embodiment may be applied to a new tire or a retread tire.

[0168] <Tires> The tire of the present embodiment is characterized by including the tire tread rubber of the present embodiment described above. Since the tire of the present embodiment includes the tire tread rubber described above, the productivity of the tire of the present embodiment is improved while maintaining the fracture resistance.

[0169] The tire of this embodiment may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization process or the like and then further vulcanizing it, depending on the type of tire to be applied. The tire of this embodiment is preferably a pneumatic tire, and the gas to be filled in the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0170] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0171] <Analysis method for rubber components> The glass transition temperature (Tg) and bound styrene content of the styrene-butadiene rubber were measured by the following method. The SP values ​​(solubility parameters) of the natural rubber (isoprene skeleton rubber) and the styrene-butadiene rubber were calculated according to the Fedors method.

[0172] (1) Glass transition temperature (Tg) The synthesized styrene-butadiene rubber was used as a sample, and a DSC curve was recorded using a TA Instruments DSC250 while heating from -100°C at 20°C / min under a helium flow of 50 mL / min. The peak top (inflection point) of the DSC differential curve was determined as the glass transition temperature.

[0173] (2) Bound styrene content The synthesized styrene-butadiene rubber was used as a sample, and 100 mg of the sample was made into 100 mL of chloroform and dissolved to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the sample was measured based on the amount of absorption of ultraviolet light by the phenyl group of styrene at a wavelength (around 254 nm). The measurement device used was a spectrophotometer "UV-2450" manufactured by Shimadzu Corporation.

[0174] <Method of analyzing resin components> The softening point and weight average molecular weight of the resin component were measured by the following methods. The SP value (solubility parameter) of the resin component was calculated according to the Fedors method.

[0175] (3) Softening point The softening point of the resin component was measured in accordance with JIS-K2207-1996 (ring and ball method).

[0176] (4) Weight average molecular weight The average molecular weight of the resin component was measured by gel permeation chromatography (GPC) under the following conditions, and the weight average molecular weight in terms of polystyrene was calculated. Column temperature: 40℃ ·Injection volume: 50μL Carrier and flow rate: Tetrahydrofuran 0.6mL / min Sample preparation: Dissolve approximately 2.5 mg of resin component in 10 mL of tetrahydrofuran.

[0177] <Preparation and Evaluation of Rubber Composition> The rubber compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were prepared by mixing and kneading the components according to the compounding recipes shown in Table 1. The unvulcanized viscosity and fracture resistance of the resulting rubber compositions were evaluated by the following methods. The results are shown in Table 1. In addition, from the results of Examples 1 and 3, the unvulcanized viscosity and the fracture resistance of Example 6 were calculated.

[0178] (5) Unvulcanized viscosity In accordance with JIS K6300-1, the unvulcanized viscosity of the rubber composition [Mooney viscosity ML 1+4 (130°C)] was measured and expressed as an index with the reciprocal of the unvulcanized viscosity of Comparative Example 1 set as 100. A larger index value indicates a lower unvulcanized viscosity and better functionality during kneading.

[0179] (6) Destruction resistance The rubber composition thus obtained was vulcanized to obtain a vulcanized rubber test piece. A tensile test was carried out on the vulcanized rubber test piece in accordance with JIS K6251 to measure the tensile stress at 300% elongation (M300), the tensile strength at break (Tb), and the elongation at break (Eb). The product of these (M300×Tb×Eb) was used as an index of fracture resistance performance, and was expressed as an index with Comparative Example 1 being set at 100. The larger the index value, the larger the product (M300×Tb×Eb) and the more excellent the fracture resistance performance.

[0180] [Table 1]

[0181] *1 Natural rubber: TSR#20, SP value = 8.20 (cal / cm 3 ) 1 / 2 *2 Low Tg modified SBR: Hydrocarbyloxysilane compound modified styrene-butadiene rubber synthesized by the following method, Tg = -65°C, SP value = 8.65 (cal / cm 3 ) 1 / 2 *3 Silica: Tosoh Silica Corporation, product name "Nipsil AQ" *4 Carbon black: Asahi Carbon Co., Ltd., product name "#80" *5 Resin component: Hydrogenated C 5 based resin, manufactured by Eastman, product name "Registered Trademark Impera E1780", softening point = 130℃, weight average molecular weight (Mw) = 909g / mol, SP value = 8.35 (cal / cm) 3 ) 1 / 2 *6 Oil: Idemitsu Kosan Co., Ltd., product name "Diana Process Oil NS-100" *7 Silane coupling agent: Evonik Degussa, product name "Si75" *8 Anti-aging agent: Product name "Nocrac 6C" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. *9 Vulcanization system: Sulfur, vulcanization accelerator, stearic acid, and zinc oxide are mixed in equal proportions.

[0182] <Synthesis method of low Tg modified SBR(*2)> A cyclohexane solution of 1,3-butadiene and a cyclohexane solution of styrene were added to a dried, nitrogen-substituted 800 mL pressure-resistant glass container so that the amount of 1,3-butadiene was 67.5 g and styrene was 7.5 g, and 0.6 mmol of 2,2-ditetrahydrofurylpropane was added, and 0.8 mmol of n-butyllithium was added, and polymerization was carried out at 50 ° C for 1.5 hours. At this time, 0.72 mmol of N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine was added as a modifier to the polymerization reaction system in which the polymerization conversion rate was almost 100%, and a modification reaction was carried out at 50 ° C for 30 minutes. Thereafter, 2 mL of a 5 mass % solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol was added to stop the reaction, and the mixture was dried according to a conventional method to obtain a modified SBR. Measurement of the microstructure of the resulting modified SBR revealed that the bound styrene content was 10% by mass, and the glass transition temperature (Tg) was -65°C.

[0183] It is clear from Table 1 that the rubber compositions of the examples according to the present invention are able to reduce the unvulcanized viscosity while maintaining the fracture resistance performance. On the other hand, the rubber composition of Comparative Example 2, in which [(mass parts of resin component-mass parts of oil) / mass parts of isoprene skeleton rubber] is less than 0.70, has a lower unvulcanized viscosity than the rubber composition of Comparative Example 1, but its fracture resistance is significantly reduced. [Industrial Applicability]

[0184] The rubber composition for tires of the present invention is suitable as a tread rubber for tires.

[0185] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 12_Responsible Consumption and Production" and "No. 13_Concrete measures against climate change."

Claims

1. A rubber composition for tires, comprising a rubber component, a resin component, and a filler, and containing or not containing oil, The rubber component contains an isoprene skeleton rubber and a styrene-butadiene rubber, an amount of the resin component per 100 parts by mass of the rubber component is 1 part by mass or more and less than 50 parts by mass; the resin component is at least partially hydrogenated; The following formula (1): 0.70≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene skeleton rubber≦1.18 (1) The rubber composition for tires is characterized by satisfying the following relationship.

2. 2. The rubber composition for tires according to claim 1, wherein the styrene-butadiene rubber has a glass transition temperature of less than -40°C.

3. The resin component has an SP value difference of 1.40 (cal / cm) from the isoprene skeleton rubber. ３ ) １／２ 2. The rubber composition for tires according to claim 1, wherein:

4. The resin component has an SP value difference of 0.50 (cal / cm) from the isoprene skeleton rubber. ３ ) １／２ The rubber composition for tires according to claim 3, wherein:

5. The difference in SP value between the isoprene skeleton rubber and the styrene-butadiene rubber is 0.3 (cal / cm ３ ) １／２ The rubber composition for tires according to claim 1 .

6. 2. The rubber composition for tires according to claim 1, wherein the content of the isoprene skeleton rubber is 1 to 80 parts by mass per 100 parts by mass of the rubber component.

7. The rubber composition for tires according to claim 6, wherein the content of the isoprene skeleton rubber is 1 to 40 parts by mass per 100 parts by mass of the rubber component.

8. 2. The rubber composition for tires according to claim 1, wherein the styrene-butadiene rubber is modified with a modifier having a functional group containing a nitrogen atom and an alkoxy group.

9. 2. The rubber composition for tires according to claim 1, wherein the resin component has a softening point higher than 110° C. and a weight average molecular weight in terms of polystyrene of 200 to 1600 g / mol.

10. The rubber composition for tires according to claim 9, wherein the resin component has a weight average molecular weight in terms of polystyrene of 200 to 1200 g / mol.

11. The resin component is hydrogenated C ５ based resin, hydrogenated C ５ -C ９ 2. The rubber composition for tires according to claim 1, wherein the rubber component is at least one selected from the group consisting of a cyclopentadiene-based resin, a hydrogenated dicyclopentadiene-based resin, and a hydrogenated terpene-based resin.

12. The following formula (1'): 0.79≦(parts by mass of the resin component−parts by mass of the oil) / parts by mass of the isoprene skeleton rubber≦1.00 (1′) The rubber composition for tires according to claim 1 , which satisfies the following relationship:

13. A tread rubber for a tire, comprising the rubber composition for a tire according to any one of claims 1 to 12.

14. A tire comprising a tire tread rubber according to claim 13.

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