Tire rubber composition, tread rubber, and tire

Abstract

A rubber composition for tires is provided with which it is possible to improve the wet grip performance of tires. The rubber composition for tires comprises a diene-based rubber component A, a diene-based rubber component B, and a resin component C, and is characterized in that the difference in SP value between the diene-based rubber component A and the diene-based rubber component B is 0.25 (cal / cm3)1 / 2 or larger, the difference in SP value between the resin component C and the diene-based rubber component A is 1.40 (cal / cm3)1 / 2 or less, the mass ratio R of the resin component C to the diene-based rubber component A, (resin component C) / (diene-based rubber component A), is 0.5 or greater, and, when the loss factor at a frequency F (Hz) determined with an atomic force microscope is expressed by tanδF, a given relationship (a) is satisfied when F≥100.

Description

[Technical Field]

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

[0002] Conventionally, from the standpoint of improving vehicle safety, various studies have been conducted to improve braking performance not only on dry roads but also on wet roads.

[0003] For example, Patent Document 1 discloses that applying a rubber composition, which is a blend of a thermoplastic resin and a silica-containing filler with a rubber component containing 70% by mass or more of natural rubber, to the tread rubber of a tire improves the braking performance of the tire on wet road surfaces. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2015 / 079703 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, in recent years, there has been a growing demand for further improvements in the braking performance of tires on wet surfaces (hereinafter sometimes referred to as "wet grip performance").

[0006] Therefore, the object of the present invention is to provide a tire rubber composition that can improve the wet grip performance of a tire, and a tread rubber made from such a rubber composition. Furthermore, a further objective of the present invention is to provide a tire with excellent wet grip performance. [Means for solving the problem]

[0007] The gist of the present invention for solving the above problems is as follows.

[0008] The rubber composition for a tire of the present invention is a rubber composition for a tire containing a diene rubber component A, a diene rubber component B, and a resin component C, where the difference in SP value between the diene rubber component A and the diene rubber component B is 0.25 (cal / cm F ) 1 / 2 or more, where the difference in SP value between the resin component C and the diene rubber component A is 1.40 (cal / cm 3 ) 1 / 2 or less, where the mass ratio R (resin component C / diene rubber component A) of the resin component C to the diene rubber component A is 0.5 or more, When the loss coefficient at a frequency F (Hz) measured by an atomic force microscope is defined as tanδ F , at F ≧ 100, the following formula (a): 0.30 ≦ -log 10 〔tanδ F / {(log 10 F) × R 3}〕≦ 1.80 (a) is satisfied.

[0009] Further, the tread rubber of the present invention is characterized by being composed of the above rubber composition for a tire.

[0010] Further, the tire of the present invention is characterized by including the above tread rubber.<00X0343>

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a rubber composition for a tire that can improve the wet grip performance of a tire, and a tread rubber composed of such a rubber composition. Further, according to the present invention, it is possible to provide a tire having excellent wet grip performance.

Embodiments for Carrying Out the Invention

[0012] The rubber composition for tires, tread rubber, and tires of the present invention will be described in detail below, based on embodiments thereof.

[0013] <Rubber composition for tires> The tire rubber composition of the present invention contains diene rubber component A, diene rubber component B, and resin component C. In the tire rubber composition of the present invention, the difference in SP value between the diene rubber component B and the diene rubber component A is 0.25 (cal / cm²). 3 ) 1 / 2 The above resin component C has an SP value difference of 1.40 (cal / cm²) compared to the above diene-based rubber component A. 3 ) 1 / 2 The following is a characteristic feature, wherein the mass ratio R (resin component C / diene rubber component A) of the resin component C to the diene rubber component A is 0.5 or more. Furthermore, in the tire rubber composition of the present invention, the loss coefficient at frequency F (Hz), as measured by an atomic force microscope, is tanδ F When F≧100, the following equation (a): 0.30 ≤ -log 10 [tanδ F / {(log 10 F)×R 3}〕≦1.80 (a) A further feature is that it satisfies the following conditions.

[0014] Furthermore, the tire rubber composition of the present invention may appropriately contain fillers, styrene-based thermoplastic elastomers, and other components, as long as it does not depart from the purpose of the present invention. Furthermore, in this specification, the SP values ​​(solubility parameters) for rubber and resin components shall be calculated according to the Fedors method.

[0015] In a tire rubber composition, two diene-based rubber components that are immiscible with each other (i.e., diene-based rubber component A and diene-based rubber component B) are blended, and the difference in SP value between at least one of the diene-based rubber components (i.e., diene-based rubber component A) and B is 1.40 (cal / cm²). 3) 1 / 2 By incorporating the following resin component C, the dispersion of each component in the rubber composition can be optimized, thereby improving the wet grip performance of the tire. Furthermore, the inventors have found that for the above-described tire rubber composition, a predetermined calculated value using a loss coefficient measured by an atomic force microscope shows a correlation with the wet grip performance of the tire. Specifically, in the above-described tire rubber composition, the mass ratio R (resin component C / diene rubber component A) of the resin component C to the diene rubber component A is set to 0.5 or higher, and the loss coefficient at frequency F (Hz) measured by an atomic force microscope is set to tanδ F When F≧100, the following equation (a): 0.30 ≤ -log 10 [tanδ F / {(log 10 F)×R 3}〕≦1.80 (a) It has been found that satisfying these conditions can significantly improve the wet grip performance of tires. Therefore, the rubber composition for tires of the present invention can improve the wet grip performance of tires when applied to them.

[0016] The phrase "satisfying equation (a)" above means that equation (a) is satisfied when measured at all frequencies above 100 Hz. However, since measuring at all frequencies is not practical, in practice, it means that equation (a) is satisfied when measured at at least 12 frequencies: 100, 200, 300, 500, 700, 1000, 2000, 3000, 5000, 7000, 10000, and 20000 Hz.

[0017] Below, "-log 10 [tanδ F / {(log 10 F)×R 3 The term "}" is sometimes referred to as the "predetermined calculated value."

[0018] It should be noted that the loss coefficient tanδ measured by an atomic force microscope is a completely different index from the tanδ of bulk rubber measured by a viscoelastic spectrometer. The loss coefficient tanδ measured by an atomic force microscope, which is the focus of this invention, and a predetermined calculated value using it, can be used as an evaluation index for wet grip performance, particularly brake characteristics.

[0019] Here, the measurement of the loss coefficient using an atomic force microscope can be performed according to the method described in “Nanorheological Mapping of Rubbers by Atomic Force Microscopy”, Macromolecules, 46, 1916-1922 (2013). The type of atomic force microscope is not particularly limited, and commercially available probes can be used for atomic force microscopy measurements. The measurement area is, for example, a two-dimensional space of 10 μm × 10 μm. The measurement is performed under control so that the surface temperature of the object is 15°C. Specifically, the measurement of the loss coefficient using an atomic force microscope can be performed according to the method described in the examples.

[0020] If even one frequency condition exists that causes the above predetermined calculated value to be less than 0.30, there is a risk that the improvement in wet grip performance may not be sufficiently obtained. Conversely, if even one frequency condition exists that causes the above predetermined calculated value to be greater than 1.80, the improvement in wet grip performance will be limited. In other words, in the tire rubber composition of the present invention, the range of the above predetermined calculated value from 0.30 to 1.80 is the optimal range for improving wet grip performance.

[0021] The above predetermined calculated value can be changed in combination by appropriately adjusting, for example, the type of diene rubber component A, the type of diene rubber component B, the type of resin component C, the content of resin component C, and the mass ratio R of resin component C to diene rubber component A. Furthermore, the above predetermined calculated value tends to increase by, for example, increasing the content of resin component C, increasing the mass ratio R of resin component C to diene rubber component A, or using a resin component C with a smaller difference in SP value from diene rubber component A.

[0022] (Rubber component) The tire rubber composition of the present invention contains a rubber component, which comprises at least diene-based rubber component A and diene-based rubber component B, and may further contain other rubber components.

[0023] The difference in SP values ​​between the above diene-based rubber component A and the above diene-based rubber component B is 0.25 (cal / cm²). 3 ) 1 / 2 That concludes the explanation. The difference in SP values ​​between the above diene-based rubber component A and the above diene-based rubber component B is 0.25 (cal / cm²). 3 ) 1 / 2 If the values ​​are less than 0.30 (cal / cm²), they become more easily miscible with each other, which may worsen wet grip performance. Furthermore, the difference in SP values ​​between the above diene-based rubber component A and the above diene-based rubber component B should be 0.30 (cal / cm²) from the viewpoint of effectively improving wet grip performance. 3 ) 1 / 2 Preferably, it should be 0.35 (cal / cm³). 3 ) 1 / 2 It is more preferable that it be greater than or equal to 0.40 (cal / cm³). 3 ) 1 / 2 It is even more preferable that the above conditions are met.

[0024] Furthermore, if the rubber composition contains two or more diene-based rubber components, and the difference in SP values ​​between these two or more diene-based rubber components is 0.25 (cal / cm²), 3 ) 1 / 2 Furthermore, the difference in SP value with resin component C is 1.40 (cal / cm²). 3 ) 1 / 2The following conditions may also apply, and the mass ratio R of resin component C may be 0.5 or greater. In such cases, among the two or more diene-based rubber components mentioned above, the diene-based rubber component with the smallest SP value will be considered diene-based rubber component A, and the diene-based rubber component with the largest SP value will be considered diene-based rubber component B.

[0025] -Diene-based rubber component A- Examples of rubber types for diene rubber component A include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Note that diene rubber component A may be a modified diene rubber obtained by modifying with any modifying agent, or it may be an unmodified diene rubber. Among these, from the viewpoint of effectively improving wet grip performance, diene rubber component A is preferably (modified or unmodified) natural rubber or isoprene rubber.

[0026] The content of diene-based rubber component A is preferably 1 to 80 parts by mass, and more preferably 1 to 40 parts by mass, per 100 parts by mass of rubber component. When the content of diene-based rubber component A is 1 to 80 parts by mass per 100 parts by mass of rubber component, the wet grip performance of the tire to which the rubber composition is applied can be further improved. Furthermore, when the content of diene-based rubber component A is 1 to 40 parts by mass per 100 parts by mass of rubber component, the wet grip performance of the tire to which the rubber composition is applied can be further improved. In addition, from the viewpoint of effectively and efficiently improving the wet grip performance of the tire, the content of diene-based rubber component A is preferably 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of rubber component.

[0027] It is preferable that diene-based rubber component A has a lower SP value than diene-based rubber component B. In this case, wet grip performance can be more effectively improved.

[0028] -Diene-based rubber component B- Examples of rubber types for diene rubber component B include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Note that diene rubber component B may be a modified diene rubber modified with any modifying agent, or it may be an unmodified diene rubber. Among these, diene rubber component B is preferably (modified or unmodified) butadiene rubber or styrene-butadiene rubber from the viewpoint of effectively improving wet grip performance.

[0029] The diene-based rubber component B preferably has a glass transition temperature of less than -40°C, and more preferably higher than -90°C. A glass transition temperature of less than -40°C for diene-based rubber component B improves the fuel efficiency and wear resistance of tires to which the rubber composition is applied. Furthermore, diene-based rubber components with a glass transition temperature higher than -90°C are easier to synthesize. From a similar viewpoint, the glass transition temperature of diene-based rubber component B is more preferably -45°C or lower, and even more preferably -50°C or lower. The glass transition temperature is determined by recording a DSC curve while increasing the temperature within a predetermined range, and the peak top (inflection point) of the DSC differential curve is defined as the glass transition temperature. Specifically, it is measured by the method described in the examples below.

[0030] The content of diene-based rubber component B is preferably 20 to 99 parts by mass, more preferably 30 to 99 parts by mass, even more preferably 40 to 99 parts by mass, even more preferably 50 to 99 parts by mass, and particularly preferably 60 to 99 parts by mass per 100 parts by mass of rubber component. When the content of diene-based rubber component B is 60 to 99 parts by mass per 100 parts by mass of rubber component, the wet grip performance of the tire to which the tire rubber composition is applied can be further improved, as well as the fuel efficiency can be improved. Furthermore, from the viewpoint of effectively and efficiently improving the wet grip performance of the tire, the content of diene-based rubber component B is preferably 50 parts by mass or more and 90 parts by mass or less per 100 parts by mass of rubber component.

[0031] When the diene-based rubber component B is styrene-butadiene rubber, the amount of bound styrene in the styrene-butadiene rubber is preferably less than 15% by mass. The amount of bound styrene in styrene-butadiene rubber refers to the proportion of styrene units contained in the styrene-butadiene rubber. When the amount of bound styrene in styrene-butadiene rubber is less than 15% by mass, the glass transition temperature tends to be low. From a similar viewpoint, the amount of bound styrene in 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. Furthermore, from the viewpoint of the wear resistance performance of the tire to which the rubber composition is applied, the amount of bound styrene in styrene-butadiene rubber is preferably 3% by mass or more, and even more preferably 4% by mass or more. The amount of styrene bound to styrene-butadiene rubber can be adjusted by the amount of monomer used in the polymerization of styrene-butadiene rubber, the degree of polymerization, etc.

[0032] When the diene-based rubber component B is styrene-butadiene rubber, it is preferable that the styrene-butadiene rubber is 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 wet grip performance of the tire to which the rubber composition is applied is further improved, and the balance between fuel efficiency and wear resistance is improved, and in particular, fuel efficiency 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 a functional group containing at least one nitrogen atom and at least one alkoxy group. The functional group containing a nitrogen atom is preferably selected from the following: A monovalent hydrocarbon group having 1 to 30 carbon atoms, including a linear, branched, alicyclic, or aromatic ring, having a functional group selected from the group consisting of a primary amino group, a primary amino group protected by 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 by a hydrolyzable protecting group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, an acyclic secondary amino group, an onium salt residue of an acyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, an acyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of an acyclic tertiary amine, and which may contain a linear, branched, alicyclic, or aromatic ring, or a monovalent hydrocarbon group having 1 to 30 carbon atoms, which may contain at least one heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom.

[0033] --Diene-based rubber component B of the first preferred embodiment-- The diene rubber component B is preferably styrene-butadiene rubber modified with an aminoalkoxysilane compound, and more preferably styrene-butadiene rubber with an aminoalkoxysilane compound at its ends, from the viewpoint of having a high affinity for fillers. When the ends of the styrene-butadiene rubber are modified with an aminoalkoxysilane compound, the interaction between the modified styrene-butadiene rubber and the filler (especially silica) becomes particularly large.

[0034] The modified sites of the styrene-butadiene rubber may be at the molecular ends as described above, but they may also be on the main chain. Styrene-butadiene rubber with modified molecular ends can be produced, for example, by reacting the ends of a styrene-butadiene copolymer having active ends with various modifying agents, according to the methods described in International Publication No. 2003 / 046020 and Japanese Patent Application Publication No. 2007-217562. In one preferred embodiment, the styrene-butadiene rubber with modified molecular ends can be produced by reacting an aminoalkoxysilane compound with the ends of a styrene-butadiene copolymer having active ends with a cis-1,4 bond content of 75% or more, according to the method described in International Publication No. 2003 / 046020 and Japanese Patent Application Publication No. 2007-217562, and then stabilizing it by reacting it with a carboxylic acid partial ester of a polyhydric alcohol.

[0035] The carboxylic acid partial ester of the polyhydric alcohol refers to a partial ester of a polyhydric alcohol and a carboxylic acid, and having one or more hydroxyl groups. Specifically, esters of sugars or modified sugars having 4 or more carbon atoms and fatty acids are preferably used. More preferably, these esters include (1) fatty acid partial esters of polyhydric alcohols, particularly partial esters of saturated or unsaturated higher fatty acids having 10 to 20 carbon atoms and polyhydric alcohols (monoesters, diesters, or triesters), and (2) ester compounds in which one to three partial esters of polyhydric carboxylic acids and higher alcohols are bonded to a polyhydric alcohol. The polyhydric alcohols used as raw materials for partial esters are preferably C5 or C6 sugars having at least three hydroxyl groups (which may or may not be hydrogenated), glycols, and polyhydroxy compounds. The raw material fatty acids are preferably C10 to C20 saturated or unsaturated fatty acids, such as stearic acid, lauric acid, and palmitic acid. Among the fatty acid partial esters of polyhydric alcohols, sorbitan fatty acid esters are preferred, specifically including sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate.

[0036] The above aminoalkoxysilane compound is not particularly limited, but an aminoalkoxysilane compound represented by the following general formula (i) is preferred. R 11 a -Si-(OR 12 ) 4-a ... (i)

[0037] 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 them is substituted with an amino group, a is an integer from 0 to 2, OR 12 If there are multiple ORs, each OR 12 These elements may be identical or different from each other, and the molecule does not contain an active proton.

[0038] Among the above aminoalkoxysilane compounds, aminoalkoxysilane compounds represented by the following general formula (ii) are also preferred. [ka]

[0039] In general formula (ii), n1 + n2 + n3 + n4 = 4 (where n2 is an integer between 1 and 4, and n1, n3, and n4 are integers between 0 and 3). A 1 is at least one functional group selected from saturated cyclic tertiary amine compound residues, unsaturated cyclic tertiary amine compound residues, ketimine residues, nitrile groups, (thio)isocyanate groups, isocyanuric acid trihydrocarbyl ester groups, nitrile groups, pyridine groups, (thio)ketone groups, amide groups, and first or second amino groups having hydrolyzable groups. When n4 is 2 or more, A 1 They may be the same or different, A 1 This may be a divalent group that bonds with Si to form a cyclic structure. R 21 This 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 may be the same or different if n1 is 2 or more. R 22 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 both may contain a nitrogen atom and / or a silicon atom. When n2 is 2 or more, R 22 These elements may be identical or different from one another, or they may come together to form a ring. R 23 This 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, and may be the same or different if n3 is 2 or more. R 24 This 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, and may be the same or different if n4 is 2 or more. The hydrolyzable group in the first or second amino group having a hydrolyzable group is preferably a trimethylsilyl group or a tert-butyldimethylsilyl group, with the trimethylsilyl group being particularly preferred.

[0040] The aminoalkoxysilane compound represented by the above general formula (ii) is preferably an aminoalkoxysilane compound represented by the following general formula (iii). [ka]

[0041] In general formula (iii), p1 + p2 + p3 = 2 (where p2 is an integer between 1 and 2, and p1 and p3 are integers between 0 and 1). A 2 This is NRa (where Ra is a monovalent hydrocarbon group, a hydrolyzable group, or a nitrogen-containing organic group). R 25 This 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 26 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 nitrogen-containing organic group, all of which may contain a nitrogen atom and / or a silicon atom. When p2 is 2, R 26 These elements may be identical or different from one another, or they may come together to form a ring. R 27 This 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 This 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. The hydrolyzable group is preferably a trimethylsilyl group or a tert-butyldimethylsilyl group, with the trimethylsilyl group being particularly preferred.

[0042] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (iv) or the following general formula (v). [ka]

[0043] In general formula (iv), q1 + q2 = 3 (where q1 is an integer between 0 and 2, and q2 is an integer between 1 and 3). R 31 This 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 Each of these is 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 This 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 may be the same or different when q1 is 2. R 35 This 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 may be the same or different if q2 is 2 or more.

[0044] [ka]

[0045] In general equation (v), r1 + r2 = 3 (where r1 is an integer between 1 and 3, and r2 is an integer between 0 and 2). R 36 This 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 37This is 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 more. R 38 This is 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, it may be the same or different. A specific example of an aminoalkoxysilane compound represented by general formula (v) is N-(1,3-dimethylbutylidene)-3-triethoxysilyl-1-propanamine.

[0046] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (vi) or the following general formula (vii). [ka]

[0047] In general formula (vi), R 40 This 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 This is 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 This 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 hereafter).

[0048] [ka]

[0049] In general formula (vii), R 43 and R 44 Each of these is 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 R 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 They may be the same or different.

[0050] The aminoalkoxysilane compound represented by the above general formula (ii) is also preferably an aminoalkoxysilane compound represented by the following general formula (viii) or the following general formula (ix). [ka]

[0051] In the general formula (viii), s1 + s2 is 3 (where s1 is an integer between 0 and 2, and s2 is an integer between 1 and 3). R 46 This 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 47 and R 48 Each of these is 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 They may be the same or different.

[0052] [ka]

[0053] 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 bonded 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 are preferably hydrolyzable groups, and as the hydrolyzable groups, a trimethylsilyl group and a tert-butyldimethylsilyl group are preferable, and a trimethylsilyl group is particularly preferable.

[0054] The aminoalkoxysilane compound represented by the 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).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0055] In the general formulas (x) to (xiii), the symbols U and V are each an integer of 0 to 2 and satisfy U + V = 2. R in the general formulas (x) to (xiii) 54 ~ 92These may be the same or different, and are monovalent or divalent aliphatic or alicyclic hydrocarbon groups having 1 to 20 carbon atoms, or monovalent or divalent aromatic hydrocarbon groups having 6 to 18 carbon atoms. In general formula (xiii), α and β are integers between 0 and 5.

[0056] Among the compounds satisfying general formulas (x), (xi), and (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 general formula (xiii), N,N-dimethyl-2-(3-(dimethoxymethylsilyl)propoxy)ethaneamine, N,N-bis(trimethylsilyl)-2-(3-(trimethoxysilyl)propoxy)ethaneamine, N,N-dimethyl-2-(3-(trimethoxysilyl)propoxy)ethaneamine, and N,N-dimethyl-3-(3-(trimethoxysilyl)propoxy)propane-1-amine are particularly preferred.

[0057] --Diene-based rubber component B of a second preferred embodiment-- The diene-based rubber component B is preferably styrene-butadiene rubber modified with a coupling agent represented by the following general formula (I). In this case, the fuel efficiency and wear resistance of the tire to which the rubber composition is applied can be improved. [ka]

[0058] In the above general formula (I), R 1 , R 2 and R 3Each of these 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 of these independently represents an alkyl group having 1 to 20 carbon atoms. R 8 and R 11 Each of these independently represents an alkylene group having 1 to 20 carbon atoms. R 10 This represents an alkyl group or trialkylsilyl group having 1 to 20 carbon atoms. m represents an integer between 1 and 3, and p represents either 1 or 2. R 1 ~R 11 If there are multiple instances of m and p, they are independent of each other. i, j, and k each independently represent integers between 0 and 6, where (i + j + k) is an integer between 3 and 10. A represents an organic group having 1 to 20 carbon atoms, which is a hydrocarbon group or an organic group having at least one atom selected from the group consisting of oxygen, nitrogen, silicon, sulfur, and phosphorus atoms, and which does not have active hydrogen. Here, in general formula (I), the hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of organic groups that do not have active hydrogen include hydroxyl groups (-OH), secondary amino groups (>NH), primary amino groups (-NH2), sulfhydryl groups (-SH), and other functional groups that do not have active hydrogen.

[0059] 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 is 200 × 10⁶, relative to the total amount of the modified styrene-butadiene rubber. 4 ~500×10 4 It is preferable that the modified styrene-butadiene rubber contains 0.25 to 30% by mass and has a shrinkage factor (g') of less than 0.64.

[0060] Generally, branched polymers tend to have smaller molecular size compared to linear polymers of the same absolute molecular weight, and the shrinkage factor (g') is an indicator of the ratio of the molecular size occupied by the branched polymer to that of a linear polymer of the same assumed absolute molecular weight. That is, the greater the degree of branching of the polymer, the smaller the shrinkage factor (g') tends to be. In this embodiment, intrinsic viscosity is used as an indicator of molecular size, and the linear polymer has an intrinsic viscosity [η] = -3.883M 0.771 The following relationship is assumed to apply. The shrinkage factor (g') is calculated for each absolute molecular weight of modified styrene-butadiene rubber, and the absolute molecular weight is 100 × 10 4 ~200×10 4 The average value of the shrinkage factor (g') at that time is taken as the shrinkage factor (g') of the modified styrene-butadiene rubber. Here, "branching" refers to the formation of a polymer by which other polymers directly or indirectly bond to one polymer. The "degree of branching" is the number of polymers that are directly or indirectly bonded to each other for one branch. For example, if the five styrene-butadiene copolymer chains described later are indirectly bonded to each other via coupling residues described later, the degree of branching is 5. A coupling residue is a structural unit of the modified styrene-butadiene rubber that is bonded to a styrene-butadiene copolymer chain, and is a structural unit derived from a coupling agent, for example, produced by reacting the styrene-butadiene copolymer described later with the coupling agent. A styrene-butadiene copolymer chain is a structural unit of the modified styrene-butadiene rubber, and is a structural unit derived from the styrene-butadiene copolymer, for example, produced by reacting the styrene-butadiene copolymer described later with the coupling agent. The shrinkage factor (g') is preferably less than 0.64, more preferably 0.63 or less, even 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 below 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 modified styrene-butadiene rubber with a shrinkage factor (g') within this range, the processability of the rubber composition is improved. Since the shrinkage factor (g') tends to depend on the degree of branching, it is possible to control the shrinkage factor (g') using the degree of branching as an indicator. Specifically, when a modified styrene-butadiene rubber has a branching degree of 6, its shrinkage factor (g') tends to be between 0.59 and 0.63, and when a modified styrene-butadiene rubber has a branching degree of 8, its shrinkage factor (g') tends to be between 0.45 and 0.59.

[0061] The styrene-butadiene rubber modified with the coupling agent represented by the above general formula (I) is preferably branched, with a degree of branching of 5 or more. Furthermore, the modified styrene-butadiene rubber has one or more coupling residues and styrene-butadiene copolymer chains bound to the coupling residues, and it is more preferable that the branches include branches to which five or more styrene-butadiene copolymer chains are bound to one of the coupling residues. By specifying the structure of the modified styrene-butadiene rubber such that the degree of branching is 5 or more and the branches include branches to which five or more styrene-butadiene copolymer chains are bound to one coupling residue, the shrinkage factor (g') can be more reliably reduced to less than 0.64. The number of styrene-butadiene copolymer chains bound to one coupling residue can be confirmed from the value of the shrinkage factor (g'). Furthermore, the modified styrene-butadiene rubber is more preferably branched, with a degree of branching of 6 or more. The modified styrene-butadiene rubber also has one or more coupling residues and styrene-butadiene copolymer chains bound to these coupling residues, and it is even more preferable that the branching includes branches in which 6 or more styrene-butadiene copolymer chains are bound to one of the coupling residues. By specifying the structure of the modified styrene-butadiene rubber such that it has a degree of branching of 6 or more and that the branching includes branches in which 6 or more styrene-butadiene copolymer chains are bound to one coupling residue, the shrinkage factor (g') can be reduced to 0.63 or less. Furthermore, the modified styrene-butadiene rubber has branching, and it is even more preferable that the degree of branching is 7 or more, and even more preferable that the degree of branching is 8 or more. The upper limit of the degree of branching is not particularly limited, but it is preferably 18 or less. In addition, the modified styrene-butadiene rubber has one or more coupling residues and styrene-butadiene copolymer chains bound to the coupling residues, and it is even more preferable that the branching includes branches in which 7 or more styrene-butadiene copolymer chains are bound to one of the coupling residues, and it is particularly preferable that the branching includes branches in which 8 or more styrene-butadiene copolymer chains are bound to one of the coupling residues. By specifying the structure of the modified styrene-butadiene rubber so that the degree of branching is 8 or more, and the branching includes branches in which 8 or more styrene-butadiene copolymer chains are bound to one coupling residue, the shrinkage factor (g') can be reduced to 0.59 or less.

[0062] Preferably, at least one end of the styrene-butadiene copolymer chain is bonded to a silicon atom of a coupling residue. In this case, the ends of multiple styrene-butadiene copolymer chains may be bonded to one silicon atom. Alternatively, the end of a styrene-butadiene copolymer chain may be bonded to an alkoxy or hydroxyl group having 1 to 20 carbon atoms, and as a result, that silicon atom may constitute an alkoxysilyl or silanol group having 1 to 20 carbon atoms.

[0063] The modified styrene-butadiene rubber can be an oil-applied rubber to which an extensible oil has been added. The modified styrene-butadiene rubber may be oil-applied or non-oil-applied, but from the viewpoint of abrasion resistance, it is preferable that the Mooney viscosity measured at 100°C is 20 to 100, and more preferably 30 to 80.

[0064] The weight-average molecular weight (Mw) of the modified styrene-butadiene rubber is preferably 20 × 10⁻⁶. 4 300 x 10 4 The following is more 50 × 10 4 That is all, fer64×10 4 The above is preferable to 80 × 10 4 That concludes the explanation. Furthermore, the weight-average molecular weight is preferably 250 × 10⁻⁶. 4 The following, and more preferably 180 × 10 4 The following, more preferably 150 × 10 4 The following applies: The weight-average molecular weight is 20 × 10 4 With the above characteristics, the low loss and abrasion resistance of the rubber composition can be sufficiently improved. Also, the weight-average molecular weight is 300 × 10 4 The processability of the rubber composition is improved if the following conditions are met.

[0065] The modified styrene-butadiene rubber has a molecular weight of 200 × 10¹⁶ based on the total amount (100% by mass) of the modified styrene-butadiene rubber. 4 500 x 10 4It is preferable to include the following modified styrene-butadiene rubber (hereinafter also referred to as "specific high molecular weight component") in an amount of 0.25% by mass or more and 30% by mass or less. When the content of the specific high molecular weight component is 0.25% by mass or more and 30% by mass or less, the low loss and abrasion resistance of the rubber composition can be sufficiently improved. The modified styrene-butadiene rubber preferably contains 1.0% by mass or more of the specific high molecular weight component, more preferably 1.4% by mass or more, even more preferably 1.75% by mass or more, even more preferably 2.0% by mass or more, particularly preferably 2.15% by mass or more, and most preferably 2.5% by mass or more. Furthermore, the modified styrene-butadiene rubber preferably contains 28% by mass or less of the specific high molecular weight component, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 18% by mass or less. In this specification, the "molecular weight" of the rubber component refers to the molecular weight equivalent to standard polystyrene, obtained by GPC (gel permeation chromatography). To obtain a modified styrene-butadiene rubber in which the content of a specific high molecular weight component is within this range, it is preferable to control the reaction conditions in the polymerization and reaction steps described later. For example, in the polymerization step, the amount of the organic monolithium compound used as a polymerization initiator, as described later, can be adjusted. Furthermore, in the polymerization step, whether using a continuous or batch polymerization method, it is preferable to use a method that has a residence time distribution, that is, to broaden the time distribution of the growth reaction.

[0066] In the modified styrene-butadiene rubber, the molecular weight distribution (Mw / Mn), expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), is preferably 1.6 or more and 3.0 or less. If the molecular weight distribution of the modified styrene-butadiene rubber is within this range, the processability of the rubber composition will be good.

[0067] The method for producing the modified styrene-butadiene rubber is not particularly limited, but it is preferable to have 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 the active end of the styrene-butadiene copolymer with a reactive compound with five or more functionalities (hereinafter also referred to as a "coupling agent").

[0068] The polymerization step is preferably carried out by a growth reaction using a living anionic polymerization reaction, which allows for the acquisition of a styrene-butadiene copolymer having active ends, and thus a modified styrene-butadiene rubber with a high degree of modification. The styrene-butadiene copolymer is obtained by copolymerizing 1,3-butadiene and styrene.

[0069] The amount of the aforementioned organic monolithium compound used as a polymerization initiator is preferably determined by 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 is related to the degree of polymerization, that is, to the number-average molecular weight and / or weight-average molecular weight. Therefore, to increase the molecular weight, it is good to adjust the amount of polymerization initiator to decrease, and 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 ease of industrial availability and ease of controlling the polymerization reaction. In this case, a styrene-butadiene copolymer having an alkyl group at the polymerization initiation end is obtained. Examples of alkyllithium compounds include n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenilithium. Among the alkyllithium compounds, n-butyllithium and sec-butyllithium are preferred from the viewpoint of ease of industrial availability and ease of controlling the polymerization reaction. These organic monolithium compounds may be used individually or in combination of two or more.

[0070] In the polymerization step, examples of polymerization reaction modes include batch and continuous polymerization reaction modes. In the continuous mode, one or more connected reactors can be used. Continuous reactors include, for example, tank-type or tubular reactors equipped with stirrers. In the continuous mode, monomers, an inert solvent, and a polymerization initiator are preferably fed continuously into the reactor, a polymer solution containing the polymer is obtained in the reactor, and the polymer solution is discharged continuously. Batch reactors include, for example, tank-type reactors equipped with stirrers. In the batch mode, monomers, an inert solvent, and a polymerization initiator are preferably fed, monomers are added continuously or intermittently during polymerization as needed, a polymer solution containing the polymer is obtained in the reactor, and the polymer solution is discharged after polymerization is complete. In this embodiment, in order to obtain a styrene-butadiene copolymer with a high proportion of active ends, a continuous mode is preferred, as it allows for the continuous discharge of the polymer and enables it to be used for the next reaction in a short time.

[0071] The polymerization step is preferably carried out in an inert solvent. Examples of solvents include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents are not limited to the following, but examples include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; and hydrocarbons consisting of aromatic hydrocarbons such as benzene, toluene, and xylene, and mixtures thereof. Treating impurities such as allenes and acetylenes with organometallic compounds before the polymerization reaction tends to yield styrene-butadiene copolymers with high concentrations of active ends, and is therefore preferable because it tends to yield modified styrene-butadiene rubber with a high degree of modification.

[0072] In the polymerization step described above, a polar compound may be added. By adding a polar compound, styrene can be randomly copolymerized with 1,3-butadiene, and polar compounds tend to be used as vinylizing agents to control the microstructure of the 1,3-butadiene moiety. Examples of the polar compounds that can be used 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-butyrate, sodium-tert-butyrate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used individually or in combination of two or more.

[0073] In the polymerization step, the polymerization temperature is preferably 0°C or higher, more preferably 120°C or lower, and particularly preferably 50°C to 100°C, from the viewpoint of productivity. Within this range, it tends to be possible to ensure a sufficient amount of coupling agent reacting with the active ends after polymerization is complete.

[0074] The amount of bound butadiene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably 40% by mass or more and 100% by mass or less, and more preferably 55% by mass or more and 80% by mass or less. Furthermore, the amount of bound styrene in the styrene-butadiene copolymer or modified styrene-butadiene rubber is not particularly limited, but is preferably greater than 0% by mass and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less. When the amounts of bound butadiene and bound styrene are within the above range, the low loss and abrasion resistance of the rubber composition can be further improved. Furthermore, the amount of bound styrene can be measured by ultraviolet absorption of the phenyl group, and from this, the amount of bound butadiene can also be determined.

[0075] In the styrene-butadiene copolymer or modified styrene-butadiene rubber, the amount of vinyl bond in the butadiene bond unit is not particularly limited, but is preferably 10 mol% to 75 mol%, and more preferably 20 mol% to 65 mol%. When the amount of vinyl bond is within the above range, the low loss and abrasion resistance of the rubber composition can be further improved. Furthermore, for modified styrene-butadiene rubber, the amount of vinyl bonds (1,2-bonds) in the butadiene bond unit can be determined using Hampton's method [RRHampton, Analytical Chemistry, 21, 923 (1949)].

[0076] The alkoxysilyl groups in the coupling agent represented by the general formula (I) above tend to react with the active end of the styrene-butadiene copolymer, for example, to dissociate alkoxylithium and form a bond between the end of the styrene-butadiene copolymer chain and the silicon of the coupling residue. The number of alkoxysilyl groups in the coupling residue is obtained by subtracting the number of SiOR groups lost due to the reaction from the total number of SiOR groups in one molecule of the coupling agent. In addition, the azasilyl groups in the coupling agent form >N-Li bonds and bonds between the end of the styrene-butadiene copolymer and the silicon of the coupling residue. Note that the >N-Li bonds tend to readily become >NH and LiOH with water during finishing. Furthermore, unreacted alkoxysilyl groups remaining in the coupling agent tend to readily become silanols (Si-OH groups) with water during finishing.

[0077] The reaction temperature in the reaction step is preferably the same as the polymerization temperature of the styrene-butadiene copolymer, more preferably 0°C to 120°C, and even more preferably 50°C to 100°C. Furthermore, the temperature change from the end of the polymerization step until the addition of the coupling agent is preferably 10°C or less, and more preferably 5°C or less. The reaction time in the reaction step is preferably 10 seconds or more, and more preferably 30 seconds or more. The time from the end of the polymerization step to the start of the reaction step is preferably shorter from the viewpoint of coupling rate, but more preferably within 5 minutes. Mixing in the reaction step may be done by mechanical stirring, stirring with a static mixer, or any other method. If the polymerization step is continuous, it is preferable that the reaction step is also continuous. For example, a tank-type or tubular-type reactor with a stirrer may be used in the reaction step. The coupling agent may be diluted with an inert solvent and continuously supplied to the reactor. If the polymerization step is batch-type, the coupling agent may be added to the polymerization reactor or transferred to another reactor for the reaction step.

[0078] In the above general formula (I), A is preferably represented by any of the following general formulas (II) to (V). By representing A with any of the general formulas (II) to (V), a modified styrene-butadiene rubber with superior performance can be obtained.

[0079] [ka] In the above general formula (II), B 1 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer from 1 to 10. B when multiple groups exist. 1 They are all independent of each other.

[0080] [ka] In the above general formula (III), B 2 B represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms.3 represents an alkyl group with 1 to 20 carbon atoms, and a represents an integer from 1 to 10. When multiple instances of each exist, B... 2 and B 3 They are all independent of each other.

[0081] [ka] In the above general formula (IV), B 4 represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer from 1 to 10. B when multiple groups exist. 4 They are all independent of each other.

[0082] [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 from 1 to 10. B when multiple groups exist. 5 They are all independent of each other.

[0083] In the above general formulas (II) to (V), B 1 B 2 B 4 B 5 Regarding this, examples of hydrocarbon groups having 1 to 20 carbon atoms include alkylene groups having 1 to 20 carbon atoms.

[0084] Preferably, in the general formula (I), A is represented by the general formula (II) or (III), and k represents 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 from 2 to 10. More preferably, in the general formula (I), A is represented by the general formula (II), k represents 0, and in the general formula (II), a represents an integer from 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 Examples include tris(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine, and among these, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine and tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane are particularly preferred.

[0085] The amount of the compound represented by general formula (I) added as the coupling agent can be adjusted so that the number of moles of styrene-butadiene copolymer to the number of moles of the coupling agent reacts in a desired stoichiometric ratio, thereby tending to achieve the desired degree of branching. Specifically, the number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, of the number of moles of the coupling agent. In this case, in general formula (I), the number of functional groups of the coupling agent ((m-1)×i+p×j+k) is preferably an integer between 5 and 10, and more preferably an integer between 6 and 10.

[0086] To obtain a modified styrene-butadiene rubber having the aforementioned specific polymer component, the molecular weight distribution (Mw / Mn) of the styrene-butadiene copolymer should preferably be 1.5 to 2.5, more preferably 1.8 to 2.2. Furthermore, it is preferable that the resulting modified styrene-butadiene rubber exhibits a single peak in its molecular weight curve determined by GPC. When the peak molecular weight of the modified styrene-butadiene rubber determined by GPC is Mp1 and the peak molecular weight of the styrene-butadiene copolymer is Mp2, it is preferable that the following equation holds true. (Mp1 / Mp2)<1.8×10-12×(Mp2-120×10 4 ) 2 +2 MP2 is 20x10 4 80 x 10 4 Below, MP1 is 30x10 4 The above 150 x 10 4 The following is more preferable. Mp1 and Mp2 are determined by the method described in the examples below.

[0087] The modification rate of the modified styrene-butadiene rubber is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. A modification rate of 30% by mass or more further improves the low loss and abrasion resistance of the rubber composition.

[0088] After the reaction step described above, an inactivator, neutralizing agent, etc., may be added to the copolymer solution as needed. Examples of inactivators include, but are not limited to, water; and alcohols such as methanol, ethanol, and isopropanol. Examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture with 9 to 11 carbon atoms, mainly centered around 10); aqueous solutions of inorganic acids; and carbon dioxide. Furthermore, from the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferable to add antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)propinate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol to the modified styrene-butadiene rubber.

[0089] Known methods can be used to obtain the modified styrene-butadiene rubber from the polymer solution. Examples of such methods include separating the solvent by steam stripping, filtering out the polymer, and then dehydrating and drying it to obtain the polymer; concentrating the solution in a flushing tank and then defoliating it with a vent extruder or the like; and directly defoliating it with a drum dryer or the like.

[0090] A modified styrene-butadiene rubber obtained by reacting a coupling agent represented by the above general formula (I) with a styrene-butadiene copolymer is, for example, represented by the following general formula (VI). [ka]

[0091] In 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 It is preferable that this is the case. The styrene-butadiene copolymer chain is a constituent unit of modified styrene-butadiene rubber, and is a structural unit derived from styrene-butadiene copolymer, for example, produced by reacting styrene-butadiene copolymer with a coupling agent. R 12 , R 13 and R 14 Each of these independently represents either a single bond or an alkylene group having 1 to 20 carbon atoms. R 15 and R 18Each of these independently represents an alkyl group having 1 to 20 carbon atoms. R 16 , R 19 , and R 20 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. R 17 and R 21 Each of these independently represents an alkylene group having 1 to 20 carbon atoms. R 22 This represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x are integers between 1 and 3, where x ≤ m; p is 1 or 2; y is an integer between 1 and 3, where y ≤ (p + 1); and z is an integer between 1 and 2. When there are multiple instances of D and R 12 ~R 22 m, p, x, y, and z are independent of each other and may be the same or different. Furthermore, 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 an organic group having a hydrocarbon group with 1 to 20 carbon atoms, or at least one atom selected from the group consisting of oxygen, nitrogen, silicon, sulfur, and phosphorus atoms, and which does not have active hydrogen. The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. Examples of organic groups that do not have active hydrogen include organic groups that do not have functional groups containing active hydrogen, such as hydroxyl groups (-OH), secondary amino groups (>NH), primary amino groups (-NH2), and sulfhydryl groups (-SH).

[0092] In the above general formula (VI), A is preferably represented by any of the above general formulas (II) to (V). By having A represented by any of the above general formulas (II) to (V), the low loss and wear resistance of the rubber composition can be further improved.

[0093] --Diene-based rubber component B of a third preferred embodiment-- The diene rubber component B is also preferably styrene-butadiene rubber, in which at least one end is modified with a modifying agent containing a compound represented by the following general formula (1) (alkoxysilane). [ka]

[0094] By using styrene-butadiene rubber modified with a modifier containing an oligosiloxane and a tertiary amino group, which are filler affinity groups, as the rubber component, the dispersibility of fillers such as silica can be improved. As a result, the rubber composition of the present invention has improved filler dispersibility, which greatly improves low loss performance, reduces the rolling resistance of tires to which the rubber composition is applied, and improves fuel efficiency.

[0095] In the above general formula (1), R 1 ~R 8 Each of these is an alkyl group having 1 to 20 carbon atoms; L 1 and L 2 Each of these is an alkylene group having 1 to 20 carbon atoms; and n is an integer between 2 and 4.

[0096] Specifically, in equation (1), R 1 ~R 4 Each of these may be independently substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, and the R 1 ~R 4 When substitution occurs, each can be independently substituted with one or more substituents selected from the group consisting of C1-C10 alkyl groups, C3-C10 cycloalkyl groups, C1-C10 alkoxy groups, C4-C10 cycloalkoxy groups, C6-C12 aryl groups, C6-C12 aryloxy groups, C2-C12 alkanoyloxy groups (Ra-COO-, where Ra is an alkyl group with 1-9 carbon atoms), C7-C13 aralkyloxy groups, C7-C13 arylalkyl groups, and C7-C13 alkylaryl groups. More specifically, the aforementioned R1 ~R 4 R may be a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and more specifically, the R 1 ~R 4 Each of these may independently be a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.

[0097] Also, in equation (1), R 5 ~R 8 Each of these is independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, more specifically a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or more specifically a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and in the case of substitution, R comes first. 1 ~R 4 It can be substituted with substituents as described above. Note that the above R 5 ~R 8 If the substituent is not an alkyl group but a hydrolyzable substituent, NR 5 R 6 and NR 7 R 8 The bond can be hydrolyzed to NH in the presence of moisture, which can adversely affect the processability of the polymer.

[0098] More specifically, in the compound represented by formula (1) above, R 1 ~R 4 R is a methyl group or an ethyl group, 5 ~R 8 This can be an alkyl group having 1 to 10 carbon atoms.

[0099] The amino group in the compound represented by formula (1), i.e., NR 5 R 6 and NR 7 R 8 It is preferable that the tertiary amino group is a tertiary amino group. The tertiary amino group provides even better processability when the compound represented by formula (1) is used as a modifying agent. Note that the above R 5 ~R 8If a protecting group to protect the amino group is bonded, or if hydrogen is bonded, it may be difficult to realize the effect of the compound represented by formula (1). If hydrogen is bonded, the anion reacts with hydrogen during the modification process and loses its reactivity, making the modification reaction itself impossible. If a protecting group is bonded, the modification reaction takes place, but the bonded group remains at the polymer end and is deprotected by hydrolysis during post-processing, becoming a primary or secondary amino group. This deprotected primary or secondary amino group may cause increased viscosity in the compound during subsequent blending, potentially leading to reduced processability.

[0100] Furthermore, L in the compound represented by formula (1) 1 and L 2 These are, independently, substituted or unsubstituted alkylene groups having 1 to 20 carbon atoms. More specifically, L 1 and L 2 Each of these can be an alkylene group having 1 to 10 carbon atoms, or more specifically, an alkylene group having 1 to 6 carbon atoms, such as a methylene group, an ethylene group, or a propylene group.

[0101] L in the compound represented by formula (1) 1 and L 2 Regarding this, the closer the distance between the Si atom and N atom within 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 subsequent processing steps, and the secondary amino group generated at this time is likely to be washed away by water during post-processing. In the modified styrene-butadiene rubber produced, it becomes difficult for the amino group to bond with fillers such as silica, and as a result, the effect of improving the dispersibility of the filler may decrease. Considering the improvement effect depending on the length of the bond between Si and N, the aforementioned L 1 and L 2 Each of these is more preferably an alkylene group having 1 to 3 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and more specifically, it can be a propylene group. 1 and L 2 First, R 1 ~R4 It can be substituted with substituents as described above.

[0102] Furthermore, the compound represented by formula (1) is preferably one of the compounds represented by the following structural formulas (1-1) to (1-5), for example, because it is possible to achieve even better low loss performance. [ka]

[0103] The compound represented by formula (1) has an alkoxysilane structure that binds to the active end of the styrene-butadiene copolymer, while the Si-O-Si structure and the three or more amino groups bound to the ends exhibit affinity for fillers such as silica. Compared to conventional modifiers containing one amino group in the molecule, this compound promotes bonding between the filler and the modified styrene-butadiene rubber. Furthermore, the degree of binding to the active end of the styrene-butadiene copolymer is uniform, and when observing the change in molecular weight distribution before and after coupling, the molecular weight distribution remains constant even after coupling, without becoming significantly larger than before. Therefore, there is no deterioration in the physical properties of the modified styrene-butadiene rubber itself, and aggregation of the filler within the rubber composition is prevented, improving the dispersibility of the filler and thus improving the processability of the rubber composition. These effects, in particular, make it possible to improve fuel efficiency and wet grip performance in a balanced manner when the rubber composition is applied to tires.

[0104] The compound represented by formula (1) can be produced through a condensation reaction represented by the following reaction scheme. [ka]

[0105] In the above reaction scheme, R 1 ~R 8 , L 1 and L 2, and n are the same as those defined in formula (1) above, and R' and R'' are arbitrary substituents that do not affect the condensation reaction. For example, R' and R'' are each independently R 1 ~R 4 It can be the same as any one of the following.

[0106] The reaction in the above reaction scheme proceeds in the presence of an acid, and the acid can be any acid that is commonly used in condensation reactions, without limitation. Those skilled in the art can select the optimal acid according to various process variables such as the type of reactor in which the reaction is carried out, the starting materials, and the reaction temperature.

[0107] Furthermore, the styrene-butadiene rubber modified with a modifying agent containing the compound represented by formula (1) above may have a narrow molecular weight distribution of 1.1 to 3.0 (Mw / Mn, also called the "polydispersion index (PDI)"). 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 decrease when applied to a rubber composition. Considering the remarkable effect of controlling the molecular weight distribution of the modified styrene-butadiene rubber on improving tensile properties and viscoelasticity, the molecular weight distribution of the modified styrene-butadiene rubber is preferably in the range of 1.3 to 2.0. Furthermore, by using the modifying agent, the molecular weight distribution of the modified styrene-butadiene rubber becomes similar to that of the styrene-butadiene copolymer before modification.

[0108] The molecular weight distribution of the modified styrene-butadiene rubber can be calculated from the ratio of the weight-average molecular weight (Mw) to the logarithmic-average molecular weight (Mn) (Mw / Mn). In this case, the number-average molecular weight (Mn) is the common average of the individual polymer molecular weights calculated by measuring the molecular weights of n polymer molecules, summing these molecular weights, and dividing by n, while the weight-average molecular weight (Mw) represents the molecular weight distribution of the polymer composition. The average of the overall molecular weight can be expressed in grams per mole (g / mol). Furthermore, the weight-average molecular weight and number-average molecular weight are polystyrene-equivalent molecular weights, respectively, analyzed by gel permeation chromatography (GPC).

[0109] Furthermore, the modified styrene-butadiene rubber satisfies the above-mentioned molecular weight distribution conditions, and at the same time, its number-average molecular weight (Mn) can be 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 has 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. If 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, there is a risk of reduced tensile properties when applied to the rubber composition. Furthermore, if the weight-average molecular weight (Mw) exceeds 4,000,000 g / mol, or the number-average molecular weight (Mn) exceeds 2,000,000 g / mol, the processability of the modified styrene-butadiene rubber will decrease, worsening the workability of the rubber composition, making mixing difficult, and making it 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) simultaneously with the molecular weight distribution, it can improve the viscoelasticity and processability of a rubber composition in a well-balanced manner when applied to it.

[0110] The modified styrene-butadiene rubber preferably has a vinyl bond content of 5% or more in the butadiene portion, more preferably 10% or more, and more preferably 60% or less. By setting the vinyl bond content of the butadiene portion within the above range, the glass transition temperature can be adjusted to an appropriate range.

[0111] The modified styrene-butadiene rubber may have a Mooney viscosity (MV) of 40 to 140, specifically 60 to 100, at 100°C. When the Mooney viscosity is within this range, it can exhibit better processability. The Mooney viscosity can be measured using a Mooney viscometer, such as the Monsanto MV2000E, at 100°C and a rotor speed of 2±0.02 rpm, using the large rotor. The sample used in this measurement is left at room temperature (23±3°C) for at least 30 minutes, then 27±3g is taken and placed inside the die cavity, and the platen is operated for measurement.

[0112] As described above, it is preferable that one end of the modified styrene-butadiene rubber is modified with a modifying agent containing the compound represented by the general formula (1), but it is preferable that the other end is further modified with a modifying agent containing the compound represented by the 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 higher level of both fuel efficiency and wet grip performance can be achieved in the tire to which the rubber composition is applied. [ka]

[0113] In the above general formula (2), R 9 ~R 11 These are, independently of each other, hydrogen; C1-C30 alkyl groups; C2-C30 alkenyl groups; C2-C30 alkynyl groups; C1-C30 heteroalkyl groups, C2-C30 heteroalkenyl groups; C2-C30 heteroalkynyl groups; C5-C30 cycloalkyl groups; C6-C30 aryl groups; or C3-C30 heterocyclic groups. Also, in equation (2), R 12 This is a single bond; a substituent-substituted or unsubstituted C1-C20 alkylene group; a substituent-substituted or unsubstituted C5-C20 cycloalkylene group; or a substituent-substituted or unsubstituted C5-C20 arylene group, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. Also, in equation (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 an active group represented by the following general formula (2a) or general formula (2b), where m is an integer from 1 to 5, and R 13 At least one of them is an operator represented by the following general formula (2a) or general formula (2b), and when m is an integer from 2 to 5, multiple R 13 They may be identical or different from one another.

[0114] [ka]

[0115] In the above general formula (2a), R 14 This is a substituent-substituted or unsubstituted C1-C20 alkylene group; a substituent-substituted or unsubstituted C5-C20 cycloalkylene group; or a substituent-substituted or unsubstituted C6-C20 arylene group, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. Furthermore, in equation (2a), R 15 and R 16 These are, independently of each other, C1-C10 alkyl groups, C5-C10 cycloalkyl groups, or C6-C20 aryl groups, or unsubstituted C1-C20 alkylene groups. Furthermore, in equation (2a), R 17 R is a hydrogen atom; 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, where X is an N, O, or S atom, except when X is O or S, R 17 It does not exist.

[0116] [ka]

[0117] In the above general formula (2b), R 18 This is a substituent-substituted or unsubstituted C1-C20 alkylene group; a substituent-substituted or unsubstituted C5-C20 cycloalkylene group; or a substituent-substituted or unsubstituted C6-C20 arylene group, where the substituent is a C1-C10 alkyl group, a C5-C10 cycloalkyl group, or a C6-C20 aryl group. Also, in equation (2b), R 19 and R 20 These are, independently of each other, C1-C30 alkyl groups; C2-C30 alkenyl groups; C2-C30 alkynyl groups; C1-C30 heteroalkyl groups; C2-C30 heteroalkenyl groups; C2-C30 heteroalkynyl groups; C5-C30 cycloalkyl groups; C6-C30 aryl groups; and C3-C30 heterocyclic groups.

[0118] Furthermore, in the compound represented by the above general formula (2), R 9 ~R 11 R is independently of 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. 12 R is a single bond; or an unsubstituted alkylene group having 1 to 10 carbon atoms, 13 R 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 an active group represented by the above general formula (2a) or general formula (2b), wherein in the above general formula (2a), 14 R is an unsubstituted alkylene group having 1 to 10 carbon atoms. 15 and R 16 These are unsubstituted alkylene groups having 1 to 10 carbon atoms, 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 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.

[0119] More specifically, the compound represented by the general formula (2) can be a compound represented by the following structural formulas (2-1) to (2-3). [Chemical formula]

[0120] When the styrene-butadiene copolymer is modified with a modifier containing the compound represented by the general formula (2), the modifier containing the compound represented by the formula (2) is used as a polymerization initiator. Specifically, for example, in a hydrocarbon solvent, by polymerizing a butadiene monomer and a styrene monomer in the presence of a modifier containing the compound represented by the formula (2), a modifying group derived from the compound represented by the formula (2) can be imparted to the styrene-butadiene copolymer.

[0121] squared -Other rubber The rubber component may further contain other rubber components. The content of the other rubber components is preferably 35 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, and particularly preferably 0 parts by mass (that is, the rubber component consists only of the diene rubber component A and the diene rubber component B) per 100 parts by mass of the rubber component.

[0122] (Resin component C) The rubber composition for a tire of the present invention contains a resin component C. The resin component C has a difference in SP value from the diene rubber component A of 1.40 (cal / cm 3 ) 1 / 2It is as follows, and the mass ratio R (resin component C / diene rubber component A) with respect to the diene rubber component A is 0.5 or more.

[0123] The difference in the SP value between the resin component C and the above diene rubber component A is 1.40 (cal / cm 3 ) 1 / 2 By being as follows, the compatibility with the diene rubber component A becomes high, the mobility of the rubber component is controlled, and the hysteresis loss (tanδ) in the low temperature region can be improved. Therefore, the wet grip performance of the tire to which the rubber composition is applied is improved. The difference in the SP value between the resin component C and the diene rubber component A is preferably 1.35 (cal / cm 3 ) 1 / 2 preferably is as follows, 0.50 (cal / cm 3 ) 1 / 2 more preferably is as follows, 0.45 (cal / cm 3 ) 1 / 2 more preferably is as follows, 0.30 (cal / cm 3 ) 1 / 2 more preferably is as follows, 0.25 (cal / cm 3 ) 1 / 2 is more preferably as follows.

[0124] When the mass ratio R (resin component C / diene rubber component A) of the resin component C with respect to the diene rubber component A is less than 0.5, there is a possibility that the effect of improving the wet grip performance of the tire to which the rubber composition is applied cannot be sufficiently obtained. From the viewpoint of effectively improving the wet grip performance, the mass ratio R (resin component C / diene rubber component A) of the resin component C with respect to the diene rubber component A is preferably 0.65 or more, more preferably 0.7 or more, and still more preferably 0.8 or more. Also, the mass ratio R (resin component C / diene rubber component A) of the resin component C with respect to the diene rubber component A is preferably 2.0 or less, more preferably 1.9 or less, and still more preferably 1.8 or less.

[0125] The content of resin component C is preferably 20 parts by mass or more and 50 parts by mass or less per 100 parts by mass of rubber component. When the content of resin component C per 100 parts by mass of rubber component is 20 parts by mass or more, the effect of the resin component is fully expressed, and when it is 50 parts by mass or less, the resin component is less likely to precipitate from the tire, and the effect of the resin component can be fully expressed. Furthermore, within this range, the loss coefficient measured by atomic force microscopy tends to be favorable to the present invention, and the wet grip performance of the tire can be improved more effectively. From a similar viewpoint, the content of resin component C per 100 parts by mass of rubber component is more preferably 25 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably less than 50 parts by mass, even more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0126] The resin component C preferably has a softening point higher than 110°C and a weight-average molecular weight of 200 to 1600 g / mol in polystyrene terms. In this case, compatibility with rubber components such as diene-based rubber component A is increased, and the wet grip performance of the tire can be further improved.

[0127] If the softening point of resin component C is higher than 110°C, the tire to which the rubber composition is applied can be sufficiently reinforced. From the same viewpoint as above and from the viewpoint of tire wear resistance, the softening point of resin component C is more 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. Furthermore, from the same viewpoint as above and 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] If the weight-average molecular weight of resin component C, in terms of polystyrene, is 200 g / mol or higher, the resin component is less likely to precipitate from the tire, and the effects of the resin component can be fully expressed. If it is 1600 g / mol or lower, the resin component is more compatible with the rubber component. From the viewpoint of suppressing the precipitation of resin components from the tire and suppressing the deterioration of the tire appearance, the weight-average molecular weight of resin component C in terms of polystyrene is preferably 500 g / mol or more, more preferably 550 g / mol or more, more preferably 600 g / mol or more, more preferably 650 g / mol or more, and even more preferably 700 g / mol or more. Furthermore, from the viewpoint of further improving the compatibility of the resin component with the rubber component and further enhancing the effect of the resin component, the weight-average molecular weight of resin component C in terms of polystyrene 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.

[0129] Weight-average molecular weight (Mw) of resin component C in terms of polystyrene HR (Unit is g / mol) Softening point (Ts) of resin component C HR The ratio (Ts) (unit is °C) HR / Mw HR The ratio (Ts) is preferably 0.07 or higher, more preferably 0.083 or higher, more preferably 0.095 or higher, more preferably 0.104 or higher, more preferably 0.125 or higher, more preferably 0.135 or higher, more preferably 0.14 or higher, and even more preferably 0.141 or higher. 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. The softening point and weight-average molecular weight of resin component C, in terms of polystyrene, can be determined by the method described in the examples below.

[0130] The resin component C is preferably a hydrogenated resin. In this case, the compatibility with the rubber component, particularly the diene-based rubber component A, is increased, and the wet grip performance can be further improved. A hydrogenated resin refers to a resin obtained by reducing and hydrogenating a resin, and it is sufficient if it is at least partially hydrogenated. Examples of resins that can be used as raw materials for hydrogenated resin components include C5 resins, C5-C9 resins, C9 resins, terpene resins, dicyclopentadiene resins, terpene-aromatic compound resins, etc. These resins may be used individually or in combination of two or more. Furthermore, resin component C is a hydrogenated resin, and the difference in SP value between it and diene-based rubber component A is 0.50 (cal / cm²). 3 ) 1 / 2 The following is preferable:

[0131] Examples of C5 resins include aliphatic petroleum resins obtained by (co)polymerizing C5 fractions obtained by the thermal decomposition of naphtha in the petrochemical industry. The C5 fraction typically contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, as well as diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. Commercially available C5 resins can be used.

[0132] C5-C9 resin refers to C5-C9 synthetic petroleum resin, and examples of C5-C9 resins include petroleum-derived C5-C 11Examples include solid polymers obtained by polymerizing fractions using Friedel-Crafts catalysts such as AlCl3 and BF3, and more specifically, copolymers mainly composed of styrene, vinyltoluene, α-methylstyrene, indene, etc. As for C5-C9 resins, resins with a low amount of C9 or higher components are preferred from the viewpoint of compatibility with rubber components. Here, "low amount of C9 or higher components" means that the amount of C9 or higher components in the total resin is less than 50% by mass, preferably 40% by mass or less. Commercially available C5-C9 resins can be used.

[0133] C9 resins refer to C9 synthetic petroleum resins, specifically solid polymers obtained by polymerizing the C9 fraction using Friedel-Crafts type catalysts such as AlCl3 or BF3. Examples of C9 resins include copolymers mainly composed of indene, α-methylstyrene, vinyltoluene, etc.

[0134] Terpene resins are solid resins obtained by polymerizing turpentine oil, which is obtained simultaneously when rosin is obtained from pine trees, or polymer components separated therefrom, using a Friedel-Crafts type catalyst. Examples include β-pinene resin and α-pinene resin. As a representative example of terpene-aromatic compound resins, terpene-phenol resins can be obtained. These terpene-phenol resins can be obtained by reacting terpenes with various phenols using a Friedel-Crafts type catalyst, or by further condensation with formalin. There are no particular restrictions on the terpenes used as raw materials, but monoterpene hydrocarbons such as α-pinene and limonene are preferred, those containing α-pinene are more preferred, and α-pinene is particularly preferred. The skeleton may also contain styrene or the like.

[0135] Dicyclopentadiene resins (DCPD resins) refer to resins obtained by polymerizing dicyclopentadiene using, for example, Friedel-Crafts type catalysts such as AlCl3 or BF3.

[0136] Furthermore, the resin used as the raw material for the hydrogenated resin component may include, for example, a resin copolymerized with a C5 fraction and dicyclopentadiene (DCPD) (C5-DCPD resin). Here, if the dicyclopentadiene-derived component in the total resin is 50% by mass or more, the C5-DCPD resin is considered to be included in the dicyclopentadiene resin. If the dicyclopentadiene-derived component in the total resin is less than 50% by mass, the C5-DCPD resin is considered to be included in the C5 resin. The same applies even if a small amount of a third component or the like is included.

[0137] From the viewpoint of improving compatibility with rubber components and further enhancing the wet grip performance of tires to which the rubber composition is applied, resin component C is preferably at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated C9 resins, hydrogenated dicyclopentadiene resins (hydrogenated DCPD resins), and hydrogenated terpene resins, more preferably at least one selected from the group consisting of hydrogenated C5 resins, hydrogenated C5-C9 resins, hydrogenated dicyclopentadiene resins, and hydrogenated terpene resins, even more preferably at least one selected from the group consisting of hydrogenated C5 resins and hydrogenated C5-C9 resins, and particularly preferably a hydrogenated C5 resin. Furthermore, it is preferable that the resin has at least a hydrogenated DCPD structure or a hydrogenated cyclic structure in its monomer.

[0138] (Filler) The rubber composition for tires of the present invention may contain a filler. The inclusion of a filler improves the reinforcing properties of the rubber composition. The filler content in the rubber composition is preferably in the range of 40 to 125 parts by mass per 100 parts by mass of the rubber component. If the filler content in the rubber composition is 40 parts by mass or more per 100 parts by mass of the rubber component, the reinforcement of the tire to which the rubber composition is applied is sufficient and the wear resistance can be improved. If it 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. Furthermore, from the viewpoint of reducing the rolling resistance of the tire (from the viewpoint of improving fuel efficiency), the filler content 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, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of further improving the wet grip performance of the tire, the filler content 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, per 100 parts by mass of the rubber component.

[0139] -silica- The aforementioned filler preferably contains silica and has a nitrogen adsorption specific surface area (BET method) of 100 m². 2 / g or more 330m 2 It is more preferable to include silica with a nitrogen adsorption specific surface area (BET method) of less than / g. 2 If the amount is 330 m² or more, the rubber composition can sufficiently reinforce the tire to which it is applied, and the rolling resistance of the tire can be reduced. 2 If the value is less than / g, the elastic modulus of the rubber composition will not become too high, and the wet grip performance of the tire to which the rubber composition is applied can be further improved. From the viewpoint of further lowering rolling resistance and improving the wear resistance of the tire, the nitrogen adsorption specific surface area (BET method) of silica is 130m². 2 It is preferable that it be 150m or more / g. 2 It is even more preferable that the nitrogen adsorption specific surface area of ​​silica be 300 m² or more. Furthermore, from the viewpoint of further improving the wet grip performance of the tire, the specific surface area of ​​silica adsorbing nitrogen (BET method) is 300 m². 2It is preferably below / g, and more preferably 280 m 2 It is more preferably below / g, and even more preferably 270 m 2 It is even more preferably below / g.

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

[0141] From the viewpoint of improving the mechanical strength of the tire and the wear resistance performance, the content of silica in the rubber composition is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, even more preferably 50 parts by mass or more, and still more preferably 55 parts by mass or more with respect 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, even more preferably 100 parts by mass or less, and still more preferably 95 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0142] - Carbon black - The filler preferably contains carbon black. The carbon black can reinforce the rubber composition and improve the wear resistance performance of the rubber composition. The carbon black is not particularly limited, and examples thereof include carbon black of GPF, FEF, HAF, ISAF, and SAF grades. These carbon blacks may be used alone or in combination of two or more.

[0143] From the viewpoint of improving the wear resistance of the rubber composition and the tire to which it is applied, the carbon black content 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 rubber components. Furthermore, from the viewpoint of the workability of the rubber composition, the carbon black content in the rubber composition is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less, per 100 parts by mass of rubber components. 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. A silica proportion of 80% by mass or more improves the mechanical strength of the tire to which the rubber composition is applied and reduces rolling resistance.

[0144] -Other fillers- In addition to silica and carbon black, the aforementioned filler may also include inorganic fillers such as clay, talc, calcium carbonate, and aluminum hydroxide. The other fillers mentioned above are preferably included in such a range that the proportion of silica in the filler is 70% by mass or more. A silica proportion of 70% by mass or more in the filler improves the mechanical strength of the tire to which the rubber composition is applied and further reduces rolling resistance. More preferably, the silica proportion in the filler is 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.

[0145] (Styrene-based thermoplastic elastomer) The tire rubber composition of the present invention 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), where the styrene-based polymer portion forms physical crosslinks and acts as 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 entirely hydrogenated. Note that styrene-based thermoplastic elastomer (TPS) is thermoplastic, while the rubber component (preferably diene rubber) is not. Therefore, in this specification, styrene-based thermoplastic elastomer (TPS) is not included in the rubber component. The content of styrene-based thermoplastic elastomer (TPS) is preferably in the range of 1 to 30 parts by mass per 100 parts by mass of the rubber component.

[0146] Examples of the styrene-based thermoplastic elastomer (TPS) include styrene / butadiene / styrene (SBS) block copolymer, styrene / isoprene / styrene (SIS) block copolymer, styrene / butadiene / isoprene / styrene (SBIS) block copolymer, styrene / butadiene (SB) block copolymer, styrene / isoprene (SI) block copolymer, styrene / butadiene / isoprene (SBI) block copolymer, styrene / ethylene / butylene / styrene (SEBS) block copolymer, styrene / ethylene / propylene / styrene (SEPS) block copolymer, styrene / ethylene / ethylene / propylene / styrene (SEEPS) block copolymer, styrene / ethylene / butylene (SEB) block copolymer, styrene / ethylene / propylene (SEP) block copolymer, and styrene / ethylene / ethylene / propylene (SEEP) block copolymer.

[0147] (Other ingredients) The rubber composition for tires of the present invention may contain, as appropriate, the rubber components, resin components, fillers, styrene-based thermoplastic elastomers described above, and, if necessary, various components commonly used in the rubber industry, such as silane coupling agents, antioxidants, waxes, softeners, processing aids, stearic acid, zinc oxide (zinc oxide), vulcanization accelerators, vulcanizing agents, etc., selected within a range that does not impair the purpose of the present invention. Commercially available products can be suitably used as these compounding agents.

[0148] When the tire rubber composition of the present invention contains silica, it is preferable to include a silane coupling agent in order to improve the effect of the silica. The silane coupling agent may be 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 include N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropylbenzothiazolyl tetrasulfide. The content of the silane coupling agent is preferably in the range of 2 to 20 parts by mass, and more preferably in the range of 5 to 15 parts by mass, per 100 parts by mass of silica.

[0149] Examples of the aforementioned antioxidants 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), and N,N'-diphenyl-p-phenylenediamine (DPPD). The content of the antioxidant is not particularly limited, but 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.

[0150] Examples of the wax include paraffin wax and microcrystalline wax. The amount of the wax is not particularly limited, but 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.

[0151] The content of the zinc oxide (zinc oxide) is not particularly limited, but 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.

[0152] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiram-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators. These vulcanization accelerators may be used individually or in combination of two or more. There are no particular restrictions on the content of the vulcanization accelerator, but it is preferably in the range of 0.1 to 5 parts by mass, and more preferably in the range of 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0153] Examples of the vulcanizing agent include sulfur. The content of the vulcanizing agent is preferably in the range of 0.1 to 10 parts by mass, and more preferably in the range of 1 to 4 parts by mass, as sulfur, per 100 parts by mass of the rubber component.

[0154] (Method for manufacturing rubber composition) The method for producing the rubber composition is not particularly limited, but for example, it can be produced by mixing the rubber component, resin component, and filler described above with various components as needed, and then kneading, heating, extruding, etc. Furthermore, the obtained rubber composition can be vulcanized to produce vulcanized rubber.

[0155] There are no particular restrictions on the mixing conditions, and various conditions such as the input volume of the mixing device, the rotation speed of the rotor, the ram pressure, as well as the mixing temperature, mixing time, and the type of mixing device can be appropriately selected according to the purpose. Examples of mixing devices include Banbury mixers, intermixes, kneaders, and rolls, which are commonly used for mixing rubber compositions.

[0156] There are no particular restrictions on the heat treatment conditions, and various conditions such as heat treatment temperature, heat treatment time, and heat treatment equipment can be appropriately selected according to the purpose. Examples of such heat treatment equipment include heat treatment roll machines commonly used for heat treatment of rubber compositions.

[0157] There are no particular restrictions on the extrusion conditions, and various conditions such as extrusion time, extrusion speed, extrusion equipment, and extrusion temperature can be appropriately selected according to the purpose. Examples of extrusion equipment include extruders typically used for extruding rubber compositions. The extrusion temperature can be determined as appropriate.

[0158] There are no particular restrictions on the apparatus, method, and conditions for performing the vulcanization, and they can be appropriately selected according to the purpose. Typical vulcanization apparatuses include molding vulcanizers using molds, which are commonly used for vulcanizing rubber compositions. The vulcanization temperature is typically around 100-190°C.

[0159] <Tread Rubber> The tread rubber of the present invention is characterized by comprising the above-described tire rubber composition. Because the tread rubber of the present invention comprises the above-described tire rubber composition, applying it to a tire can improve the wet grip performance of the tire. The tread rubber of the present invention may be applied to new tires or to retreaded tires.

[0160] <Tires> The tire of the present invention is characterized by having the above-described tread rubber. Because the tire of the present invention has the above-described tread rubber, it has excellent wet grip performance.

[0161] The tire of the present invention may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, depending on the type of tire to be applied, or by molding a semi-vulcanized rubber that has undergone a pre-vulcanization process, and then further vulcanizing it. Preferably, the tire of the present invention is a pneumatic tire, and as the gas to fill the pneumatic tire, in addition to ordinary air or air with adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium can be used. [Examples]

[0162] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0163] <Method for analyzing rubber components> The glass transition temperature (Tg) and styrene content of the synthesized modified SBR were measured by the following method. Furthermore, the SP values ​​(solubility parameters) of each rubber component were calculated according to the Fedors method.

[0164] (1) Glass transition temperature (Tg) Using the synthesized modified styrene-butadiene rubber as a sample, a DSC250 from TA Instruments was used to record the DSC curve while heating from -100°C to 20°C / min under a helium flow of 50 mL / min. The peak top (inflection point) of the DSC differential curve was defined as the glass transition temperature.

[0165] (2) Amount of bound styrene Synthesized modified styrene-butadiene rubber was used as the sample. 100 mg of the sample was dissolved in 100 mL of chloroform to prepare the measurement sample. The amount of bound styrene (mass%) relative to 100% mass of the sample was measured by the amount of ultraviolet absorption at a wavelength (around 254 nm) by the phenyl group of styrene. A Shimadzu UV-2450 spectrophotometer was used as the measuring instrument.

[0166] <Method for analyzing resin components> The softening point and weight-average molecular weight of the resin components were measured by the following method. Furthermore, the SP value (solubility parameter) of the resin components was calculated according to the Fedors method.

[0167] (3) Softening point The softening point of the resin component was measured in accordance with JIS-K2207-1996 (ring-sphere method).

[0168] (4) Weight average molecular weight Under the following conditions, the average molecular weight of the resin components was measured by gel permeation chromatography (GPC), and the weight-average molecular weight in terms of polystyrene was calculated. Column temperature: 40°C ·Injection volume: 50μL • Carrier and flow rate: Tetrahydrofuran 0.6 mL / min Sample preparation: Dissolve approximately 2.5 mg of resin component in 10 mL of tetrahydrofuran.

[0169] <Preparation of rubber composition> The rubber compositions of the examples and comparative examples were prepared by mixing and kneading each component according to the formulations shown in Table 1.

[0170] <Production and evaluation of vulcanized rubber> The rubber compositions of the obtained examples and comparative examples were vulcanized at 145°C for 33 minutes to obtain vulcanized rubber test pieces. The loss coefficient and wet grip performance of the obtained vulcanized rubber were measured using an atomic force microscope and evaluated using the following method. And I did it using the following method.

[0171] (5) Loss coefficient using an atomic force microscope The loss coefficient was measured using an atomic force microscope according to the method described in “Nanorheological Mapping of Rubbers by Atomic Force Microscopy”, Macromolecules, 46, 1916-1922 (2013). Specifically, the vulcanized rubbers of the obtained examples and comparative examples were cut into sections (vulcanized rubber test pieces) of approximately 100 μm × 100 μm in size and 2 μm thick using a Leica cryomicrotome at -80 to -100°C, and these sections were adsorbed onto a mica substrate. Then, using an atomic force microscope (Oxford Instruments, product name "MFP-3D"), the cantilever was manipulated to measure the loss coefficient tanδ at frequency F (Hz). F The following measurements were taken. The conditions for the measurements were as follows: • Measurement and analysis program: Oxford Instruments • Probe: OLYMPUS Corporation, product name "OMCL-AC240FS-B2", tip radius: approx. 10 nm (typ.), spring constant: approx. 2 N / m (typ.) • Surface temperature of the object being measured: 15℃ • Measurement frequency F (Hz): 100Hz to 20000Hz (12 points in total: 100, 200, 300, 500, 700, 1000, 2000, 3000, 5000, 7000, 10000, and 20000)

[0172] Loss factor tanδ at frequency F (Hz) F For the measurement, the loss coefficient was measured at 16 points in a 10 μm × 10 μm two-dimensional space, and the average value was taken as tanδ. F This was calculated as follows: the frequency F (Hz) and tanδ. F Furthermore, using the value of the mass ratio R(component C / component A) of component C to component A in the rubber composition, "-log 10 [tanδ F / {(log 10 F)×R 3 The calculation for}) was performed using 12 points. In each example, the maximum and minimum values ​​of the above calculations are shown in Table 1.

[0173] (6) Wet grip performance A portable friction tester was used to measure the coefficient of friction of vulcanized rubber test pieces on a wet asphalt road surface. The evaluation results were expressed as an index, with the coefficient of friction of Comparative Example 1 set to 100. A higher index value indicates a higher coefficient of friction and superior wet grip performance.

[0174] [Table 1]

[0175] *1 Natural rubber: TSR#20, SP value = 8.20 (cal / cm 3 ) 1 / 2 *2 Modified SBR: Hydrocarbyloxysilane compound-modified styrene-butadiene rubber synthesized by the method described below, Tg = -65℃, SP value = 8.65 (cal / cm²) 3 ) 1 / 2 *3 Filler: Silica, manufactured by Tosoh Silica Co., Ltd., product name "NipSeal AQ" *4 Resin components: Hydrogenated C5 resin, manufactured by Eastman, trade name "Registered Trademark Impera E1780", softening point = 130℃, weight-average molecular weight (Mw) = 909 g / mol, SP value = 8.35 (cal / cm²) 3 ) 1 / 2 *5 Silane coupling agent: Evonik DeGussa, product name "Si75" *6 Anti-aging agent: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrack 6C" *7 Wax: Manufactured by Nippon Seiro Co., Ltd., product name "Ozo Ace 0701" *8 Vulcanization accelerator A: Manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noxellar DM-P" *9 Vulcanization accelerator B: Manufactured by Sanshin Chemical Industry Co., Ltd., product name "Sunceller NS-G" *10 -log 10 [tanδ F / {(log 10 F)×R3 Calculated value of})

[0176] <Method for synthesizing modified SBR (*2)> In a dried, nitrogen-purged 800 mL pressure-resistant glass container, cyclohexane solutions of 1,3-butadiene and styrene were added to a total volume of 67.5 g of 1,3-butadiene and 7.5 g of styrene. 0.6 mmol of 2,2-ditetrahydrofurylpropane was added, followed by 0.8 mmol of n-butyllithium, and polymerization was carried out at 50°C for 1.5 hours. When the polymerization conversion rate reached nearly 100%, 0.72 mmol of N,N-bis(trimethylsilyl)-3-[diethoxy(methyl)silyl]propylamine was added as a modifying agent, and the modification reaction was carried out at 50°C for 30 minutes. Subsequently, 2 mL of a 5% by mass solution of 2,6-di-t-butyl-p-cresol (BHT) in isopropanol was added to stop the reaction, and the modified SBR was obtained by drying according to a conventional method. Microstructure measurements of the obtained modified SBR revealed that the amount of bound styrene was 10% by mass, and the glass transition temperature (Tg) was -65°C.

[0177] Table 1 shows that the rubber composition of the embodiment according to the present invention has excellent wet grip performance. On the other hand, the rubber composition of the comparative example does not satisfy formula (a) above (i.e., the minimum calculated value is less than 0.30 and / or the maximum calculated value is greater than 1.80), and therefore has inferior wet grip performance. [Industrial applicability]

[0178] According to the present invention, it is possible to provide a tire rubber composition that can improve the wet grip performance of a tire, and a tread rubber made from such a rubber composition. Furthermore, according to the present invention, it is possible to provide a tire with excellent wet grip performance.

Claims

1. A tire rubber composition containing diene rubber component A, diene rubber component B, and resin component C, Diene-based rubber component A has a lower SP value than diene-based rubber component B. The difference in SP values ​​between the diene-based rubber component A and the diene-based rubber component B is 0.35 (cal / cm²). ３ ) １／２ That's all. The resin component C has an SP value difference of 0.30 (cal / cm²) compared to the diene-based rubber component A. ３ ) １／２ The following: The aforementioned resin component C has a softening point higher than 110°C and 141°C or lower, and a weight-average molecular weight in terms of polystyrene equivalent of 200 to 1600 g / mol. The mass ratio R (resin component C / diene rubber component A) of the resin component C to the diene rubber component A is 0.7 or more. The loss coefficient at frequency F (Hz), measured by an atomic force microscope, is tanδ. Ｆ When F ≥ 100, the following equation (a): 0.30≦-log １０ 〔tanδ Ｆ / {(log １０ F)×R ３ }〕≦1.80 (a) A rubber composition for tires that satisfies the following conditions.

2. The tire rubber composition according to claim 1, wherein the content of the diene-based rubber component A is 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component.

3. The tire rubber composition according to claim 1 or 2, wherein the diene-based rubber component A is natural rubber or isoprene rubber.

4. The tire rubber composition according to any one of claims 1 to 3, wherein the diene-based rubber component B is butadiene rubber or styrene-butadiene rubber.

5. The tire rubber composition according to any one of claims 1 to 4, wherein the resin component C is a hydrogenated resin.

6. The tire rubber composition according to any one of claims 1 to 5, wherein the content of the resin component C is 20 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component.

7. The aforementioned resin component C is hydrogenated C ５ based resin, hydrogenated C ５ -C ９ The tire rubber composition according to claim 5 or 6, wherein it is at least one selected from the group consisting of a resin, a hydrogenated dicyclopentadiene resin, and a hydrogenated terpene resin.

8. A tread rubber characterized by comprising the tire rubber composition described in any one of claims 1 to 7.

9. A tire characterized by comprising the tread rubber described in claim 8.

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