Rubber composition for tires, and tire

Abstract

The purpose of the present invention is to provide: a rubber composition for tires which exhibit excellent rolling performance, wet performance, wear resistance, and deterioration resistance; and a tire produced using the composition. This rubber composition for tires comprises a diene-based rubber including a modified conjugated-diene rubber, silica, a silane coupling agent, and an alkyltriethoxysilane, wherein the modified conjugated-diene rubber is a conjugated-diene rubber satisfying a specific expression and having a modification group including a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto, the proportion of the modified conjugated-diene rubber in the diene-based rubber being 25 mass% or higher.

Description

Rubber composition for tires and tires

[0001] The present invention relates to a rubber composition for a tire and a tire.

[0002] BACKGROUND ART Conventionally, rubber compositions for tires containing silica in order to improve performance have been known (for example, Patent Document 1).

[0003] Patent No. 7196953

[0004] Recently, from the viewpoint of environmental issues and the like, there has been a demand for further improvements in the rolling performance of tires. In addition, from the viewpoint of safety and the like, there has also been a demand for further improvements in wet performance, wear resistance, aging resistance, etc. In this context, the present inventors have studied the conventional rubber compositions for tires described in Patent Document 1 and the like, and have found that further improvements in the rolling performance, wet performance, wear resistance, and aging resistance when made into tires are desirable.

[0005] In view of the above circumstances, the present invention aims to provide a rubber composition for tires that exhibits excellent rolling performance, wet performance, abrasion resistance, and aging resistance when made into a tire, and a tire manufactured using the rubber composition for tires.

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a specific modified conjugated diene rubber as the rubber component and containing silica, a silane coupling agent, and an alkyltriethoxysilane, and have arrived at the present invention. That is, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0007] [1] A rubber composition for tires comprising a diene rubber containing a modified conjugated diene rubber (A1), silica, a silane coupling agent, and an alkyltriethoxysilane, wherein the modified conjugated diene rubber (A1) satisfies the following formulas (1) and (2) and has a modifying group containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto, and wherein the proportion of the modified conjugated diene rubber (A1) in the diene rubber is 25% by mass or more. １０％ ≦3.1×10－６ ×Mw １０％ -2.77 (1) IVw １０％ <4.7 (2) IVw in formula (1) and formula (2) １０％ and Mw in formula (1) １０％ The weight average molecular weight (Mw) is determined by using the high molecular weight portion of the peak in the chromatogram obtained by the differential refractive index detector, which is 10% of the total area of ​​the peak. １０％ The weight average intrinsic viscosity determined using the high molecular weight portion of the peak in the chromatogram obtained by the viscosity detector, which is 10% of the area of ​​the entire peak, is defined as IVw. １０％ where the unit of weight average intrinsic viscosity is dL / g. [2] The rubber composition for a tire according to [1], wherein the modified conjugated diene rubber (A1) has a star structure with three or more branches, at least one branch of the star structure has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety has a further main chain branched structure. [3] The rubber composition for a tire according to [1] or [2], further containing a modified conjugated diene rubber (A2) other than the modified conjugated diene rubber (A1), wherein the total proportion of the modified conjugated diene rubber (A1) and the modified conjugated diene rubber (A2) in the diene rubber is 70 mass% or more. [4] The rubber composition for a tire according to [1] or [2], wherein the Mw １０％ is 2.0 x 10 ６ [5] The rubber composition for a tire according to any one of [1] to [4], wherein the content of the silica is 50 parts by mass or more per 100 parts by mass of the diene rubber. [6] The rubber composition for a tire according to any one of [1] to [5], wherein the silane coupling agent comprises 3-octanoylthio-1-propyltriethoxysilane or a sulfur-containing silane coupling agent represented by the following average composition formula (X), and the content of the silane coupling agent is 2 to 20 mass% of the content of the silica. (A) ａ (B) ｂ(C) ｃ (D) ｄ (R １ ) ｅ SiO （４－２ａ－ｂ－ｃ－ｄ－ｅ） / 2 (X) In formula (X), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R １ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, and a to e satisfy the relational expressions 0≦a<1, 0<b<1, 0<c<3, 0<d<1, 0≦e<2, 0<2a+b+c+d+e<4. [7] The rubber composition for a tire according to any one of [1] to [6], further comprising a thermoplastic resin, the thermoplastic resin comprising at least one selected from the group consisting of a terpene resin, a C5 / C9 resin, a C9 resin, a DCPD resin, a DCPD / C9 resin, a hydrogenated C5 / C9 resin, a hydrogenated C9 resin, a hydrogenated DCPD resin, and a hydrogenated DCPD / C9 resin. [8] The rubber composition for a tire according to any one of [1] to [7], further comprising a thermoplastic resin, wherein the thermoplastic resin comprises at least two resins selected from the group consisting of a terpene resin, a C5 / C9 resin, a C9 resin, a DCPD resin, a DCPD / C9 resin, a hydrogenated C5 / C9 resin, a hydrogenated C9 resin, a hydrogenated DCPD resin, and a hydrogenated DCPD / C9 resin. [9] A tire produced using the rubber composition for a tire according to any one of [1] to [8].

[0008] As will be described below, according to the present invention, it is possible to provide a rubber composition for a tire that exhibits excellent rolling performance, wet performance, abrasion resistance, and aging resistance when made into a tire, and a tire manufactured using the rubber composition for a tire.

[0009] 1 is an example of a GPC chromatogram. 2 is a partial cross-sectional schematic view showing an example of an embodiment of a tire of the present invention.

[0010] The rubber composition for tires of the present invention will be described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Each component may be used alone, or two or more may be used in combination. When two or more components are used in combination, the content of the components refers to the total content unless otherwise specified. Furthermore, the manufacturing method of each component is not particularly limited unless otherwise specified. Examples of manufacturing methods include conventionally known methods. Regarding the rubber composition for tires, the rolling performance, wet performance, wear resistance, and aging resistance of a tire made from the tire are also referred to simply as "rolling performance," "wet performance," "wear resistance," and "aging resistance," respectively. In this specification, a power of 10 is sometimes represented by E. For example, E+5 represents 10 to the fifth power. In the present invention, when the standard for the proportion of a component is "in the diene rubber," the diene rubber refers to the entire diene rubber including the specific conjugated diene rubber. When the standard for the content of a component is "per 100 parts by mass of the diene rubber," 100 parts by mass of the diene rubber refers to 100 parts by mass of the total diene rubber including the specific conjugated diene rubber.

[0011] [I] Rubber Composition for Tires The rubber composition for tires of the present invention (hereinafter also referred to as "the composition of the present invention") is a rubber composition for tires comprising: a diene rubber containing a modified conjugated diene rubber (A1); silica; a silane coupling agent; and an alkyltriethoxysilane; the modified conjugated diene rubber (A1) is a conjugated diene rubber that satisfies formulas (1) and (2) described below and has a modifying group containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto; and the proportion of the modified conjugated diene rubber (A1) in the diene rubber is 25% by mass or more.

[0012] The composition of the present invention, having such a structure, is believed to be able to solve the above-mentioned problems. While the reason for this is unclear, it is believed to be roughly as follows. The composition of the present invention includes, as a rubber component, a conjugated diene-based rubber (hereinafter also referred to as a "specific conjugated diene-based rubber") that satisfies the following formula (1) and formula (2) and has a modifying group (hereinafter also referred to as a "specific modifying group") containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. The specific modifying group possessed by the specific conjugated diene-based rubber is believed to interact with silica. Furthermore, formula (1) defines the relationship between the weight-average intrinsic viscosity on the high molecular weight side and the weight-average molecular weight on the high molecular weight side. However, the inventors' investigations have revealed that the specific conjugated diene-based rubber has room for improvement in terms of rolling performance and wet performance. The inventors believed that improving the dispersibility of silica in the rubber composition was necessary to achieve this improvement, and so they applied alkyltriethoxysilane to the specific conjugated diene-based rubber. This is thought to have resulted in extremely high dispersibility of silica in the composition of the present invention, leading to improvements in not only rolling performance and wet performance, but also wear resistance and aging resistance.

[0013] Each component contained in the composition of the present invention will be described below.

[0014] [1] Rubber component The composition of the present invention contains a diene rubber including a specific conjugated diene rubber as a rubber component. The composition of the present invention may further contain a diene rubber other than the specific conjugated diene rubber as a rubber component.

[0015] [Specific Conjugated Diene Rubber] The specific conjugated diene rubber is a conjugated diene rubber that satisfies the formula (1) described later and the formula (2) described later, and has a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto.

[0016] [Skeleton] The skeleton of the specific conjugated diene rubber is a polymer having repeating units derived from a conjugated diene.

[0017] <Conjugated diene> Specific examples of the conjugated diene include butadiene (particularly 1,3-butadiene), isoprene, chloroprene, etc. The conjugated diene is preferably butadiene (particularly 1,3-butadiene) or isoprene, and more preferably butadiene (particularly 1,3-butadiene), because the effects of the present invention are more excellent.

[0018] <Other Monomers> The skeleton of the specific conjugated diene rubber may have a repeating unit other than the repeating unit derived from the conjugated diene. Examples of the monomer that forms such a repeating unit (other monomer) include vinyl monomers, alkenes (e.g., ethylene, propylene, butene), etc. Examples of the vinyl monomer include aromatic vinyls (e.g., styrene), acrylonitrile, and the specific branching agents described below.

[0019] <Specific Examples> Specific examples of the skeleton of the specific conjugated diene rubber include natural rubber (NR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber, isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Examples of the aromatic vinyl-conjugated diene copolymer rubber include styrene-butadiene rubber (SBR) and styrene-isoprene copolymer rubber. The skeleton of the specific conjugated diene rubber is preferably SBR, as this provides better effects of the present invention.

[0020] [Specific modifying group] As described above, the specific conjugated diene rubber has a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent to the silicon atom. The specific modifying group may be present at the end of the skeleton of the specific conjugated diene rubber, on the main chain, or on a side chain. For reasons of better effects of the present invention, the specific modifying group preferably contains a silicon atom and an oxygen atom adjacent to the silicon atom as an alkoxysilyl group. The alkoxysilyl group is -Si(OR1) ｎ (R2) ３－ｎ(wherein R1 is an alkyl group, R2 is a hydrogen atom or an alkyl group, and n is an integer of 1 to 3). The specific modifying group preferably contains a nitrogen atom as an amino group (primary to tertiary amino group) because the effects of the present invention are more excellent. The specific modifying group is preferably a group derived from a specific modifying agent described below because the effects of the present invention are more excellent.

[0021] [Formula (1), Formula (2)] The specific conjugated diene rubber satisfies the following formulas (1) and (2). Formula (1) defines the relationship between the weight-average intrinsic viscosity on the high molecular weight side and the weight-average molecular weight on the high molecular weight side, and polymers having a small molecular size relative to their molecular weight, such as those having branches, tend to satisfy formula (1). The reason for limiting the molecular weight to the high molecular weight side is that it has a significant impact on the physical properties of the entire polymer.

[0022] IVw １０％ ≦3.1×10 －６ ×Mw １０％ -2.77 (1) IVw １０％ <4.7 (2)

[0023] IVw in formula (1) and formula (2) １０％ and Mw in formula (1) １０％ The weight average molecular weight (Mw) is determined by using a high molecular weight portion of the peak in the chromatogram obtained by the differential refractive index detector, which is 10% of the total area of ​​the peak. １０％ The weight average intrinsic viscosity determined using the high molecular weight portion of the peak in the chromatogram obtained by the viscosity detector, which is 10% of the area of ​​the entire peak, is defined as IVw. １０％ However, the unit of the weight average intrinsic viscosity is dL / g.

[0024] Hereinafter, IVw in formula (1) and formula (2) １０％ and Mw in formula (1) １０％ This will be explained in more detail.

[0025] As described above, the modified conjugated diene rubber is subjected to gel permeation chromatography (GPC) measurement using a differential refractive index detector and a viscosity detector as detectors. The specific method of GPC measurement is as follows.

[0026] Toluene containing 5 mmol / L triethylamine was used as the eluent. Three columns packed with polystyrene gel (manufactured by Tosoh Corporation under the trade names "TSKgel G4000HXL," "TSKgel G5000HXL," and "TSKgel G6000HXL") were connected together and used. The sample to be measured was dissolved in toluene to a concentration of 1 mg / mL to prepare a measurement solution. 100 μL of the measurement solution was injected into a GPC measurement device and measured at an oven temperature of 40°C and a toluene flow rate of 1 mL / min.

[0027] The weight average molecular weight is determined by using the high molecular weight side (the side with a shorter elution time) which accounts for 10% of the area of ​​the entire peak (peak attributable to the modified conjugated diene rubber) in the chromatogram (horizontal axis: elution time, vertical axis: signal intensity) obtained by the differential refractive index detector. １０％ Let's say.

[0028] In addition, among the peaks (peaks attributable to the modified conjugated diene rubber) in the chromatogram (horizontal axis: elution time, vertical axis: signal intensity) obtained by the viscosity detector, the weight-average intrinsic viscosity is determined using the portion on the high molecular weight side (shorter elution time) which accounts for 10% of the total peak area. The weight-average intrinsic viscosity thus obtained is referred to as IVw １０％ The weight average intrinsic viscosity is defined as (Σ(ηi×Mi×Ni)) / (Σ(Mi×Ni)), where Ni is the number of molecules and ηi is the intrinsic viscosity at molecular weight Mi.

[0029] An example of a GPC chromatogram (horizontal axis: elution time, vertical axis: signal intensity) is shown in Figure 1. Mw １０％ and IVw １０％ Ask for.

[0030] Examples of a method for making the modified conjugated diene rubber satisfy formula (1) include a method of changing the type and amount of the specific modifier and the type and amount of the specific branching agent in the production method of the present invention described below.

[0031] [Mw １０％ 〕 Mw １０％ is preferably 100,000 to 10,000,000, and more preferably 2.0×10 ６ It is more preferable that Mw is from 2,000,000 to 5,000,000. １０％ The Mw is preferably 3,000,000 to 5,000,000 because the effects of the present invention (particularly wear resistance) are more excellent. １０％ is preferably more than 100,000 and less than 3,000,000 because the effects of the present invention (particularly wet performance and aging resistance) are more excellent.

[0032] [IVw １０％ ) IVw １０％ In order to obtain a more excellent effect of the present invention, IVw is preferably 3.0 or more and less than 4.7. １０％ The IVw is more preferably 3.0 or more and 4.0 or less because the effects of the present invention (particularly, wear resistance) are more excellent. １０％ is more preferably greater than 4.0 and 4.5 or less, because the effects of the present invention (particularly wet performance and aging resistance) are more excellent.

[0033] [Formula (3)] The specific conjugated diene rubber preferably further satisfies the following formula (3) for the reason that the effects of the present invention (particularly wet performance and aging resistance) are more excellent.

[0034] 30≦St+Vn≦90 (3)

[0035] In formula (3), St represents the proportion (mass%) of repeating units derived from styrene relative to the entire specific conjugated diene rubber (hereinafter also referred to as the "styrene amount"), and Vn represents the proportion (mass%) of repeating units of a 1,2-vinyl structure derived from a conjugated diene (for example, butadiene) relative to the entire specific conjugated diene rubber (hereinafter also referred to as the "vinyl amount").

[0036] St+Vn is preferably more than 50 and not more than 90, because the effects of the present invention are more excellent.

[0037] St is preferably more than 10 and 50 or less because the effects of the present invention are more excellent.

[0038] Vn is preferably more than 0 and 40 or less, because the effects of the present invention are more excellent.

[0039] [Molecular Weight] The weight average molecular weight (Mw) of the specific conjugated diene rubber is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,300,000, because the effects of the present invention are more excellent. The method for measuring the weight average molecular weight (Mw) of the specific conjugated diene rubber is the same as that described above except that the entire peak is used. １０％ is the same as

[0040] [Glass transition temperature] The glass transition temperature (Tg) of the specific conjugated diene rubber is not particularly limited, but is preferably -100°C to 0°C, and more preferably -80°C to -10°C, for reasons of better effects of the present invention. The glass transition temperature can be adjusted, for example, by the amount of styrene or vinyl. In this specification, the glass transition temperature (Tg) is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 10°C / min and calculated by the midpoint method.

[0041] [Preferred Aspect 1] For reasons of better effects of the present invention, the specific conjugated diene rubber preferably has a star structure with three or more branches, more preferably has a star structure with three or more branches in which the specific modifying group is a branch point, and further preferably is a conjugated diene rubber represented by the following formula (A):

[0042]

[0043] In formula (A), X represents an n-valent group (specific modifying group) containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto, P represents a conjugated diene polymer chain, and n represents an integer of 3 or more.

[0044] As described above, X represents an n-valent group (specific modifying group) containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. X preferably contains a silicon atom and an oxygen atom adjacent thereto as an alkoxysilyl group, because the effects of the present invention are more excellent. X preferably contains a nitrogen atom as an amino group, because the effects of the present invention are more excellent.

[0045] As described above, P represents a conjugated diene polymer chain. Multiple Ps may be the same or different. The definition, specific examples, and preferred embodiments of the conjugated diene polymer chain are the same as those of the skeleton of the specific conjugated diene rubber described above.

[0046] As described above, n represents an integer of 3 or greater. There is no particular upper limit to n, but it is preferably 30 or less in order to obtain better effects of the present invention.

[0047] [Preferred Aspect 2] When the specific conjugated diene rubber has a star structure with three or more branches, at least one branched chain (conjugated diene polymer chain) of the star structure preferably has a moiety derived from a specific branching agent described below, and the moiety preferably has an additional main chain branched structure, for reasons of better effects of the present invention. Note that the main chain branched structure refers to a structure in which the branched chain (conjugated diene polymer chain) forms a branch point at a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and a polymer chain (for example, another conjugated diene polymer chain) further extends from the branch point.

[0048] [Proportion of specific conjugated diene rubber] In the present invention, the proportion of the specific conjugated diene rubber in the diene rubber is 25% by mass or more. For reasons of better effects of the present invention, the proportion is preferably 30% by mass or more, and more preferably 50% by mass or more and 90% by mass or less.

[0049] [Other Rubber Components] The rubber component may further contain a rubber component (other rubber component) other than the specific conjugated diene rubber.

[0050] (Other Diene Rubbers) Examples of the diene rubbers (other diene rubbers) other than the specific conjugated diene rubber in the diene rubber that the composition of the present invention can further contain include natural rubber (NR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubbers (e.g., styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, etc.), isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubbers (Br-IIR, Cl-IIR), chloroprene rubber (CR), etc. The other diene rubbers may be modified. However, the modification in the modified other diene rubber [modified conjugated diene rubber (A2)] does not include specific modifying groups. Examples of modifying groups that the modified other diene rubbers can have include hydroxy groups, epoxy groups, and polysiloxane groups. From the viewpoint of achieving superior effects of the present invention, the other diene rubber that can be further contained in the rubber component preferably contains natural rubber (NR), butadiene rubber (BR) or SBR, more preferably natural rubber (NR) and / or SBR, and even more preferably unmodified NR and modified SBR. The proportion of the other diene rubber in the diene rubber can be the remainder obtained by subtracting the range of the proportion of the specific conjugated diene rubber from 100% by mass. The proportion of the modified other diene rubber [modified conjugated diene rubber (A2)] in the diene rubber can be 0 to 50% by mass of the diene rubber.

[0051] When the diene rubber further contains a modified other diene rubber [modified conjugated diene rubber (A2)] other than the specific conjugated diene rubber [modified conjugated diene rubber (A1)], the total proportion of the modified conjugated diene rubber (A1) and the modified conjugated diene rubber (A2) in the diene rubber is preferably 70% by mass or more, more preferably 75 to 90% by mass, from the viewpoint of achieving better effects of the present invention. When the diene rubber further contains an unmodified diene rubber other than the specific conjugated diene rubber [modified conjugated diene rubber (A1)], the proportion of the unmodified diene rubber in the diene rubber is preferably 0 to 30% by mass, more preferably 10 to 25% by mass, from the viewpoint of achieving better effects of the present invention.

[0052] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the rubber component other than the specific conjugated diene rubber may be expressed as standard polystyrene equivalent values ​​obtained by gel permeation chromatography (GPC) measurement under the following conditions: Solvent: tetrahydrofuran Detector: RI detector

[0053] [Method for producing specific conjugated diene rubber] The method for producing the specific conjugated diene rubber is not particularly limited, but a method comprising the following steps (1) and (2) (hereinafter also referred to as the "production method of the present invention") is preferred because it provides better effects of the present invention: (1) a polymerization step of anionic polymerization of a monomer containing a conjugated diene to obtain a conjugated diene polymer; (2) a modification step of reacting the conjugated diene polymer obtained in the polymerization step with a compound containing a nitrogen atom and an alkoxysilyl group (hereinafter also referred to as the "specific modifier") to obtain a conjugated diene rubber having a specific modifying group.

[0054] [Polymerization Step] The polymerization step is a step of obtaining a conjugated diene-based polymer by anionic polymerization of a monomer containing a conjugated diene.

[0055] <Anionic Polymerization> The anionic polymerization is not particularly limited, but anionic polymerization using an organolithium compound as an initiator is preferred because it provides better effects of the present invention.

[0056] The organolithium compound is not particularly limited, and specific examples thereof include monoorganolithium compounds such as n-butyllithium (n-BuLi), sec-butyllithium, tert-butyllithium, n-propyllithium, isopropyllithium, and benzyllithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trillithiobenzene, and 1,3,5-trillithio-2,4,6-triethylbenzene. Among these, monoorganolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred, with n-butyllithium being more preferred, because they provide better effects for the present invention.

[0057] The amount of the organolithium compound used is not particularly limited, but is preferably 0.001 to 10 mol % based on the monomer, because this provides a better effect of the present invention.

[0058] <Monomer> Specific examples and preferred embodiments of the conjugated diene-containing monomer used in the polymerization step are the same as those of the conjugated diene and other monomers in the skeleton of the specific conjugated diene-based rubber described above.

[0059] (Specific branching agent) The monomer preferably contains a vinyl monomer containing an alkoxysilyl group or a halosilyl group (hereinafter also referred to as "specific branching agent"), because the effects of the present invention are more excellent. The specific branching agent is preferably an aromatic vinyl (particularly styrene) containing an alkoxysilyl group or a halosilyl group, more preferably an aromatic vinyl containing an alkoxysilyl group, and even more preferably an aromatic vinyl containing a trialkoxysilyl group, because the effects of the present invention are more excellent.

[0060] (1) Specific Examples Specific examples of aromatic vinyls containing an alkoxysilyl group include 1-(trimethoxysilyl)-4-vinylbenzene, 1,1-bis(4-trimethoxysilylphenyl)ethylene, etc. Specific examples of aromatic vinyls containing a halosilyl group include trichloro(4-vinylphenyl)silane, 1,1-bis(4-trichlorosilylphenyl)ethylene, etc.

[0061] (2) Amount Used The amount of the specific branching agent used is preferably 0.001 to 0.1% by mass, more preferably 0.005 to 0.05% by mass, based on the conjugated diene, for reasons of better effects of the present invention.

[0062] <Polar Compound> A polar compound may be added in the polymerization step. This allows the monomers to be copolymerized randomly. Polar compounds also tend to be usable as vinylating agents for controlling the microstructure of conjugated dienes. They also tend to be effective in accelerating the polymerization reaction.

[0063] Examples of polar compounds that can be used include ethers such as tetrahydrofuran, diethyl ether, dioxane, 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 and sodium tert-butylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0064] (Amount Used) The amount of the polar compound used is preferably 0.01 moles or more and 100 moles or less per mole of the initiator, because the effects of the present invention are more excellent.

[0065] [Modification Step] The modification step is a step of reacting the conjugated diene polymer obtained in the polymerization step with a modifier (specific modifier) ​​containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto, to obtain a conjugated diene rubber having a specific modifying group.

[0066] In the modification step, the active terminal of the conjugated diene polymer obtained in the polymerization step is thought to bond to the silicon atom of the specific modifying agent. For example, when the specific modifying agent contains an alkoxysilyl group, the active terminal is thought to bond to the silicon atom of the alkoxysilyl group, and the alkoxy group is thought to be released. Furthermore, when the conjugated diene polymer obtained in the polymerization step has a portion derived from a specific branching agent, in addition to the active terminal described above, the alkoxysilyl group or halosilyl group in the portion is thought to react with the specific modifying agent (e.g., alkoxysilyl group). Furthermore, the alkoxysilyl group or halosilyl group in the portion is thought to react with the active terminal of another conjugated diene polymer. As a result, a conjugated diene polymer having a portion derived from a specific branching agent will have a main chain branched structure (another conjugated diene polymer chain) in the portion.

[0067] <Specific Modifier> The specific modifier is a compound containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. For reasons of enhanced effects of the present invention, the specific modifier preferably contains the silicon atom and the oxygen atom adjacent thereto as an alkoxysilyl group (particularly, a trialkoxysilyl group) or a group containing a silazane structure (particularly, a cyclic silazane structure) in which an alkoxy group is bonded to the silicon atom of the silazane structure. Here, the silazane structure refers to a structure in which a silicon atom and a nitrogen atom are directly bonded (a structure having an Si—N bond). For reasons of enhanced effects of the present invention, the specific modifier preferably contains a nitrogen atom as a group containing an amino group (primary to tertiary amino group) or a silazane structure (particularly, a cyclic silazane structure). The specific modifier preferably has two or more (preferably three or more) moieties capable of reacting with an active terminal such as an alkoxysilyl group. When the specific modifier has a plurality of such moieties, the specific modifier functions as a coupling agent that connects conjugated diene-based polymers together.

[0068] (Specific Examples) Specific examples of the specific modifying agent include tertiary amines having an alkoxysilyl group, such as tris(3-trimethoxysilylpropyl)amine and tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine; cyclic silazanes having an alkoxysilyl group, such as 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane; tertiary amines having a group containing an alkoxysilyl group-containing cyclic silazane structure, such as tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine and tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine; bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine; bis[3 and tertiary amines having an alkoxysilyl group and a group containing a cyclic silazane structure, such as -(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, and bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine.

[0069] (Amount Used) The amount of the specific modifier used is preferably 0.01 to 1% by mass, more preferably 0.02 to 0.2% by mass, based on the conjugated diene, for reasons of better effects of the present invention.

[0070] [Other Steps] The production method of the present invention may include steps (other steps) other than the steps described above. Examples of the other steps include a polymerization termination step of adding a polymerization terminator (e.g., methanol), and a solvent removal step of removing the solvent by steam stripping.

[0071] [Molecular Weight] The preferred embodiment of the weight average molecular weight (Mw) of the rubber component is the same as that of the specific conjugated diene rubber described above.

[0072] [2] Silica The composition of the present invention contains silica. There are no particular limitations on the type of silica, and any conventionally known silica can be used. Examples of silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Silica derived from biomass, such as rice husks, may also be used. The silica may be used alone or in combination of two or more types.

[0073] [CTAB] The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of ​​silica (hereinafter, "CTAB adsorption specific surface area" may be simply referred to as "CTAB") is not particularly limited, but in order to obtain a more excellent effect of the present invention, it is preferred to use a surface area of ​​100 to 300 m. ２ / g, and 150 to 200m ２ Here, the CTAB adsorption specific surface area is a value measured in accordance with JIS K6430:2008, Appendix G.

[0074] [Content] The content of silica is preferably 50 parts by mass or more, and more preferably 70 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the diene rubber, because the effects of the present invention are more excellent.

[0075] [3] Silane Coupling Agent The composition of the present invention contains a silane coupling agent.

[0076] The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. The hydrolyzable group is not particularly limited, but examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferred because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, because the effects of the present invention are more excellent. Examples of alkoxy groups having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0077] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, such as an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, a blocked mercapto group (protected mercapto group) (e.g., a thioester group such as an octanoylthio group), and among these, a sulfide group (particularly a disulfide group or a tetrasulfide group), a mercapto group, or a blocked mercapto group is preferred because the effects of the present invention are more excellent. The silane coupling agent may be used alone or in combination of two or more.

[0078] The silane coupling agent preferably contains a sulfur-containing silane coupling agent, because this provides better effects of the present invention.

[0079] Examples of the silane coupling agent include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide (Si69), bis(3-trimethoxysilylpropyl)tetrasulfide, and bis(3-triethoxysilylpropyl)disulfide; mercapto-based silane coupling agents such as mercaptopropyltrimethoxysilane and mercaptopropyltriethoxysilane; thioester-based silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane (NXT); and sulfur-containing polysiloxane-based silane coupling agents such as sulfur-containing silane coupling agents represented by the average composition formula (X) described below.

[0080] The silane coupling agent preferably contains a thioester-based silane coupling agent or a sulfur-containing polysiloxane-based silane coupling agent, because these provide better effects of the present invention. It is more preferable that the silane coupling agent contains 3-octanoylthio-1-propyltriethoxysilane or a sulfur-containing silane coupling agent represented by the following average composition formula (X), and it is even more preferable that the silane coupling agent contains 3-octanoylthio-1-propyltriethoxysilane. In this specification, the average composition formula (X) may be referred to as "formula (X)." The sulfur-containing silane coupling agent represented by the average composition formula (X) may be referred to as "the silane coupling agent represented by formula (X)."

[0081] [Sulfur-containing silane coupling agent represented by average composition formula (X)] The silane coupling agent represented by formula (X) preferably has a polysiloxane skeleton. The polysiloxane skeleton can be linear, branched, or three-dimensional, or a combination thereof. Formula (X) is as follows: (A) ａ (B) ｂ (C) ｃ (D) ｄ (R １ ) ｅ SiO （４－２ａ－ｂ－ｃ－ｄ－ｅ） / 2 (X) In formula (X), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R １ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, and a to e satisfy the following relational expressions: 0≦a<1, 0<b<1, 0<c<3, 0<d<1, 0≦e<2, 0<2a+b+c+d+e<4.

[0082] [A] A represents a divalent organic group containing a sulfide group. A may have a heteroatom such as an oxygen atom, a nitrogen atom, or a sulfur atom. A is preferably a group represented by the following formula (A1): *-(CH2)n-Sx-(CH2)n-* (A1) In formula (A1), n ​​represents an integer of 1 to 10, x represents an integer of 1 to 6, and * represents the bonding position. Specific examples of A represented by formula (A1) include *-CH２ -S ２ -CH ２ -*, *-C ２ H ４ -S ２ -C ２ H ４ -*, *-C ３ H ６ -S ２ -C ３ H ６ -*, *-C ４ H ８ -S ２ -C ４ H ８ -*, *-CH ２ -S ４ -CH ２ -*, *-C ２ H ４ -S ４ -C ２ H ４ -*, *-C ３ H ６ -S ４ -C ３ H ６ -*, *-C ４ H ８ -S ４ -C ４ H ８ - * etc.

[0083] [B] B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms. B is preferably a monovalent hydrocarbon group having 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms. Examples include a hexyl group, an octyl group, and a decyl group.

[0084] [C] C represents a hydrolyzable group. Examples of C include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. C is preferably a group represented by the following formula (C1): *-OR ２ (C1) In formula (C1), * indicates a bonding position. ２represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group (arylalkyl group) having 6 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, and among these, an alkyl group having 1 to 5 carbon atoms is preferred. Specific examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group.

[0085] [D] D represents an organic group containing a mercapto group. D is preferably a group represented by the following formula (D1): *-(CH ２ ) ｍ —SH (D1) In formula (D1), m represents an integer of 1 to 10, and preferably an integer of 1 to 5. In the formula, * indicates a bonding position. Examples of the group represented by formula (D1) include *-CH ２ SH, *-C ２ H ４ SH, *-C ３ H ６ SH, *-C ４ H ８ SH, *-C ５ H １０ SH, *-C ６ H １２ SH, *-C ７ H １４ SH, *-C ８ H １６ SH, *-C ９ H １８ SH, *-C １０ H ２０ Examples include SH.

[0086] [R １ ] R １ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. １ Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0087] [a to e] a to e satisfy the relational expressions 0≦a<1, 0<b<1, 0<c<3, 0<d<1, 0≦e<2, 0<2a+b+c+d+e<4. a is preferably greater than 0, more preferably 0<a≦0.50. b is preferably 0.10≦b≦0.89. c is preferably 1.2≦c≦2.0. d is preferably 0.1≦d≦0.8.

[0088] [Content] The content of the silane coupling agent in the composition of the present invention is not particularly limited, but the content of the silane coupling agent is preferably 2 to 20 mass % of the above-mentioned silica content, and more preferably 5 to 15 mass %, because this provides better effects of the present invention.

[0089] [4] Alkyltriethoxysilane The composition of the present invention contains an alkyltriethoxysilane. By including an alkyltriethoxysilane in the composition of the present invention, it is believed that the dispersibility of silica in the composition of the present invention is improved, resulting in excellent rolling performance, wet performance, wear resistance, and aging resistance.

[0090] Examples of alkyltriethoxysilanes include compounds represented by the following formula (Y): １ -Si-(OCH ２ CH ３ ) ３ (Y) In formula (Y), R １ represents an alkyl group having 7 to 20 carbon atoms. Examples of the alkyl group having 7 to 20 carbon atoms include a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. Of these, an octyl group and a nonyl group are preferred because they provide better effects of the present invention.

[0091] [Content] In the composition of the present invention, the content of alkyltriethoxysilane is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 1.0 to 15.0 mass% of the above-mentioned silica content, and more preferably 2.0 to 10.0 mass%. Furthermore, in order to obtain better effects of the present invention, the content of alkyltriethoxysilane is preferably 0.1 to 10 parts by mass, more preferably 1.0 to 5.0 parts by mass, and even more preferably 1.5 to 2.5 parts by mass, per 100 parts by mass of the above-mentioned diene rubber.

[0092] [4] Optional Components The composition of the present invention may contain components (optional components) other than the above-mentioned components, as necessary. Examples of such components include fillers other than silica (preferably carbon black), oils such as process oil, thermoplastic resins, zinc oxide (zinc white), stearic acid, antioxidants, waxes, processing aids, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), vulcanization activators, and various other additives commonly used in rubber compositions.

[0093] [Thermoplastic Resin] The composition of the present invention preferably further contains a thermoplastic resin, for the reason that the effects of the present invention are more excellent.

[0094] [Specific Examples] Examples of thermoplastic resins include coumarone-based resins (e.g., coumarone resin, coumarone-indene resin, coumarone-indene-styrene resin), phenol-based resins (e.g., phenol resin, phenol-acetylene resin, phenol-formaldehyde resin), xylene-based resins (e.g., xylene resin, xylene-acetylene resin, xylene-formaldehyde resin), rosin-based resins (e.g., rosin, rosin ester, hydrogenated rosin derivative), terpene-based resins (e.g., terpene resin, modified Examples of suitable resins include aromatic terpene resins (such as aromatic modified terpene resins), terpene phenol resins, hydrogenated terpene resins, α-pinene resins, β-pinene resins, limonene resins, hydrogenated limonene resins, dipentene resins, and terpene styrene resins), styrene-based resins, petroleum-based resins (for example, C5 / C9-based resins, C9-based resins, DCPD (dicyclopentadiene)-based resins, DCPD / C9-based resins, hydrogenated C5 / C9-based resins, hydrogenated C9-based resins, hydrogenated DCPD-based resins, and hydrogenated DCPD / C9-based resins), and aliphatic saturated hydrocarbon-based resins.

[0095] The thermoplastic resin preferably contains at least one selected from the group consisting of terpene resins, C5 / C9 resins, C9 resins, DCPD resins, DCPD / C9 resins, hydrogenated C5 / C9 resins, hydrogenated C9 resins, hydrogenated DCPD resins, and hydrogenated DCPD / C9 resins, and more preferably contains a terpene resin or a C5 / C9 resin. It may also contain at least two resins selected from the above group. When containing at least two resins selected from the above group, a combination of a terpene resin and a C5 / C9 resin is preferred, because the effects of the present invention are more excellent. The terpene resin is not particularly limited. Examples include conventionally known terpene resins. The same applies to C5 / C9 resins.

[0096] [Content] In the composition of the present invention, the content of the thermoplastic resin (when two or more types of thermoplastic resins are used, the total content thereof) is not particularly limited, but in order to obtain better effects of the present invention, it is preferably 0 to 30 parts by mass, and more preferably 1 to 30 parts by mass, per 100 parts by mass of the diene rubber described above.

[0097] [Carbon Black] The composition of the present invention preferably further contains carbon black, because the effects of the present invention are more excellent. The carbon black may be used alone or in combination of two or more types. The carbon black is not particularly limited, and various grades of carbon black, such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF, can be used.

[0098] [N ２ SA] The nitrogen adsorption specific surface area (N ２ SA) is not particularly limited, but is preferably 50 to 200 m because the effect of the present invention is more excellent. ２ / g, and 70 to 150m ２ Here, the nitrogen adsorption specific surface area (N2SA) is a value obtained by measuring the amount of nitrogen adsorbed onto the surface of carbon black in accordance with JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0099] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but in order to achieve better effects of the present invention, it is preferably 1 to 100 parts by mass, and more preferably 2 to 30 parts by mass, per 100 parts by mass of the diene rubber described above.

[0100] [5] Method for Preparing Rubber Composition for Tires The method for producing the composition of the present invention is not particularly limited, and specific examples thereof include a method in which the above-mentioned components are kneaded using known methods and devices (e.g., a Banbury mixer, a kneader, a roll, etc.). When the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than the sulfur and the vulcanization accelerator at a high temperature (preferably 100 to 160°C), cool the mixture, and then mix in the sulfur or vulcanization accelerator. In addition, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0101] [II] Tire The tire of the present invention is a tire manufactured using the composition of the present invention described above. The tire of the present invention is preferably a pneumatic tire, and can be filled with air, an inert gas such as nitrogen, or other gases.

[0102] Fig. 2 shows a partial cross-sectional schematic view of a tire showing one example of an embodiment of the tire of the present invention, although the tire of the present invention is not limited to the embodiment shown in Fig. 2.

[0103] In Figure 2, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion. A carcass layer 4 having fiber cords embedded therein is mounted between the pair of left and right bead portions 1, and the ends of this carcass layer 4 are folded back and wound up around a bead core 5 and a bead filler 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed around the entire circumference of the tire on the outside of the carcass layer 4. In the bead portion 1, a rim cushion 8 is disposed in the portion that contacts the rim. At least one of reference numerals 2-3, 5-6, and 8 (preferably reference numeral 3) is formed from the composition of the present invention described above.

[0104] The tire of the present invention can be manufactured, for example, by a conventionally known method. The gas to be filled into the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

[0105] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0106] [Synthesis of Conjugated Diene Rubber] Each conjugated diene rubber was synthesized as follows.

[0107] [Conjugated diene rubber 3 (comparison)]

[0108] <Polymerization Step> An autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 1000 g / h (hour), tetramethylethylenediamine 0.059 g / h, 1,3-butadiene 153.0 g / h, 1-butene 0.352 g / h, and styrene 47.0 g / h, and then n-butyllithium was continuously added at 1.43 mmol / h, and polymerization was initiated at 70°C. Once the polymerization was sufficiently stabilized, 1-(trimethoxysilyl)-4-vinylbenzene (branching agent) was added at 0.06 g / h, and the mixture was allowed to react with stirring. The branching agent corresponds to the specific branching agent described above.

[0109] <Modification Step> To the solution flowing out from the outlet of the reactor, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine (modifier) ​​was added at 0.28 g / h, and the mixture was stirred to react.

[0110] Thereafter, methanol was added as a polymerization terminator to obtain a solution containing a conjugated diene rubber.

[0111] To the resulting solution, 1.14 parts by mass of Irganox 1520L (manufactured by BASF) was added as an antioxidant per 100 parts by mass of the conjugated diene rubber, and the solvent was then removed by steam stripping. The resulting mixture was vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber. The resulting conjugated diene rubber is also referred to as conjugated diene rubber 3.

[0112] The conjugated diene rubber 3 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, with a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) derived from the modifier, which includes a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. The conjugated diene rubber 3 has a star structure with three or more branches with the modifying group as a branching point, and the branched chain bonded to the modifying group has a portion derived from the branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0113] [Conjugated Diene Rubber 5] A solid conjugated diene rubber was obtained in the same manner as for Conjugated Diene Rubber 3, except that the amounts of each component used were changed as shown in Table 1. The obtained conjugated diene rubber is also referred to as Conjugated Diene Rubber 5.

[0114] The conjugated diene rubber 5 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, with a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) derived from the modifier, which includes a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. The conjugated diene rubber 5 has a star structure with three or more branches with the modifying group as a branching point, and the branched chain bonded to the modifying group has a portion derived from the branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0115] [Conjugated Diene Rubber 6] A solid conjugated diene rubber was obtained in the same manner as for Conjugated Diene Rubber 3, except that the amounts of each component used were changed as shown in Table 1. The obtained conjugated diene rubber is also referred to as Conjugated Diene Rubber 6.

[0116] The conjugated diene rubber 6 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, with a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) derived from the modifier, which includes a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto. The conjugated diene rubber 2 has a star structure with three or more branches with the modifying group as a branching point, and the branched chain bonded to the modifying group has a portion derived from the branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0117]

[0118] [Conjugated Diene Rubber 4 (Comparative)] 2,000 g of cyclohexane, 31.6 g of tetrahydrofuran, 122 g of styrene, and 320 g of 1,3-butadiene were charged into a nitrogen-purged 5-liter autoclave reactor. After adjusting the temperature of the reactor contents to 10°C, 4.75 mmol of n-butyllithium was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, with the maximum temperature reaching 85°C. When the polymerization conversion reached 99% (20 minutes after the start of polymerization), 10 g of 1,3-butadiene was added over 2 minutes, followed by the addition of 2.12 mmol of a compound (modifier) ​​represented by the following formula (4), and the reaction was continued for 15 minutes. The modifier corresponds to the specific modifier described above. 3.96 g of 2,6-di-tert-butyl-p-cresol was added to the resulting solution. Next, the solvent was removed by steam stripping, and the resulting mixture was dried with a heated roll adjusted to 110° C., thereby obtaining a solid conjugated diene rubber. The obtained conjugated diene rubber is also referred to as conjugated diene rubber 4.

[0119] Formula (4)

[0120] In formula (4), R １ is a hydrocarbyl group having 1 to 20 carbon atoms, and R ２ is a hydrocarbyloxy group having 1 to 20 carbon atoms, and R ３ is an alkanediyl group having 1 to 20 carbon atoms, and A ２ is the group "*-C(R ５ )=N-" or the group "*-N=C(R ５ ) -" (However, R ５ is a hydrogen atom or a hydrocarbyl group, and * is R ４ ) indicates that the bond is bonded to R. ４ is an m-valent hydrocarbyl group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms and having at least one atom selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms and having no active hydrogen. n is an integer of 1 to 3, and m is an integer of 2 to 10. In the formula, multiple R １ , R ２ , R ３ , A ２ , n may be the same or different.

[0121] The conjugated diene rubber 4 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene and styrene, with a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) derived from the modifier, which includes a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto.

[0122] [Weight-average molecular weight, weight-average intrinsic viscosity, styrene content, vinyl content, and glass transition temperature] The conjugated diene rubbers (conjugated diene rubbers 3 and 4 (comparison), conjugated diene rubbers 5 and 6) synthesized as described above were measured for Mw, Mw １０％ , IVw, IVw １０％ , St, Vn, St+Vn, and Tg are shown in Table 2. Table 2 also shows E581 used as conjugated diene rubber 1 (comparison) and NS560 used as conjugated diene rubber 2 (comparison). Details of E581 and the like will be described later. In Table 2, the "right side" refers to the right side of formula (1), "3.1 × 10 －６ ×Mw １０％ In Table 2, "applicable / inapplicable" for formula (1) indicates whether formula (1) is applicable or not. Specifically, "A" indicates whether IVw １０％ represents that formula (1) is satisfied, and "B" represents IVw １０％ In Table 2, "Suitable / unsuitable" for formula (2) indicates whether formula (2) is satisfied. Specifically, "A" indicates whether IVw １０％ represents that formula (2) is satisfied, and "B" represents IVw １０％ does not satisfy the formula (2). In Table 2, "St+Vn" in the formula (3) represents the above-mentioned St+Vn.

[0123]

[0124] As shown in Table 2, conjugated diene rubber 1 (comparison) does not satisfy formula (1) and formula (2), and therefore does not fall under the category of the above-mentioned specific conjugated diene rubber. Conjugated diene rubber 2 (comparison) satisfies formula (2), but does not satisfy formula (1), and therefore does not fall under the category of the above-mentioned specific conjugated diene rubber. Conjugated diene rubbers 3 and 4 (comparison) satisfy formula (1). As described above, conjugated diene rubbers 3 and 4 (comparison) are modified conjugated diene rubbers having a specific modifying group. However, conjugated diene rubbers 3 and 4 (comparison) do not satisfy formula (2), and therefore do not fall under the category of the above-mentioned specific conjugated diene rubber. On the other hand, as shown in Table 2, conjugated diene rubbers 5 and 6 all satisfy formula (1) and formula (2). As described above, conjugated diene rubbers 5 and 6 are modified conjugated diene rubbers having a specific modifying group. Therefore, all of the conjugated diene rubbers 5 and 6 fall under the category of the specific conjugated diene rubber described above.

[0125] [Preparation of Rubber Composition for Tire] The components in Tables 3 to 4 below were mixed in the compositions (parts by mass) shown in the tables. Specifically, first, the components in Tables 3 to 4 other than sulfur and vulcanization accelerator were mixed in a 1.8 L internal mixer at 160°C or lower for 5 minutes, and a master batch was released. Thereafter, sulfur and vulcanization accelerator were added to the master batch, and the mixture was mixed using an open roll at 100°C or lower to produce each rubber composition for tire.

[0126] [Evaluation] The following evaluations were carried out for each of the obtained rubber compositions for tires. The results are shown in Tables 3 and 4.

[0127] [Rolling Performance] Each of the obtained rubber compositions for tires was press-vulcanized in a mold (15 cm x 15 cm x 0.2 cm) at 160°C for 40 minutes to produce each vulcanized rubber sheet. Then, for the obtained vulcanized rubber sheets, tan δ (60°C) was measured in accordance with JIS K6394:2007 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) under conditions of an elongation deformation strain rate of 10%±2%, a frequency of 20 Hz, and a temperature of 60°C, and the reciprocal of tan δ (60°C) was calculated. The results were expressed as an index, with the reciprocal of tan δ (60°C) of the reference example being set to 100. In the present invention, an index of 100 or more indicates excellent rolling performance (low rolling resistance). A higher index indicates better rolling performance.

[0128] [Wet Performance] Each of the obtained rubber compositions for tires was press-vulcanized in a mold (15 cm x 15 cm x 0.2 cm) at 160°C for 40 minutes to produce a vulcanized rubber sheet. Tan δ (0°C) was measured for each of the obtained vulcanized rubber sheets in accordance with JIS K6394:2007 using a viscoelasticity spectrometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) under conditions of an elongation deformation strain rate of 10%±2%, a frequency of 20 Hz, and a temperature of 0°C, and the reciprocal of tan δ (0°C) was calculated. The results were expressed as an index, with the tan δ (0°C) of the reference example being set to 100. In the present invention, an index of 100 or more is considered to indicate excellent wet performance. A higher index indicates better wet performance.

[0129] [Wear Resistance Performance] Each of the obtained rubber compositions for tires was press-vulcanized in a mold (15 cm x 15 cm x 0.2 cm) at 160°C for 40 minutes to produce each vulcanized rubber sheet. The amount of wear of the obtained vulcanized rubber sheet was measured using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) in accordance with JIS K6264-2:2005 under conditions of a load of 15.0 kg (147.1 N) and a slip ratio of 25%. The results were expressed as an index, with the reciprocal of the amount of wear of the control example being set to 100. In the present invention, an index of 105 or more is considered to indicate excellent wear resistance. A higher index indicates better wear resistance.

[0130] [Aging Resistance] Each of the obtained rubber compositions for tires was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160°C for 40 minutes to produce a vulcanized rubber sheet. The obtained vulcanized rubber sheets were used as they were for tensile tests, and also for tensile tests after heat aging at 80°C for 168 hours. Dumbbell JIS No. 3 test pieces were prepared from each of the vulcanized rubber sheets in accordance with JIS K6251. Using the obtained test pieces, a tensile test was performed at room temperature (20°C) at a pulling rate of 500 mm / min to measure the 100% tensile stress (M100) at 100% elongation. From the results obtained, the 100% tensile stress of the test piece that was not subjected to heat aging treatment was designated as T0, and the 100% tensile stress of the test piece that was subjected to heat aging treatment (80°C, 168 hours) was designated as T1, and the rate of change in 100% tensile stress (M100) due to the presence or absence of heat aging treatment, Δ = (T1 - T0) / T0 × 100 [%], was calculated. The results were expressed as an index, with the reciprocal of the rate of change Δ of the standard example being set to 100. In the present invention, an index of 108 or more is considered to indicate excellent aging resistance. A larger index indicates better aging resistance.

[0131]

[0132]

[0133] Details of each component in Tables 3 and 4 are as follows: NR: Natural rubber, SIR20 manufactured by PT. KIRANA SAPTA, Tg: -65°C. Unmodified Conjugated diene rubber 1 (comparison): E581 (terminally modified solution polymerized SBR having a hydroxy group at the terminal) manufactured by Asahi Kasei Corporation (does not satisfy formula (1) or formula (2) and therefore does not fall under the above-mentioned specific conjugated diene rubber) Conjugated diene rubber 2 (comparison): NS560 (terminally modified SBR) manufactured by Nippon Zeon Corporation (does not satisfy formula (1) and therefore does not fall under the above-mentioned specific conjugated diene rubber) Conjugated diene rubbers 3 to 4 (comparison): Conjugated diene rubbers 3 to 4 synthesized as described above (does not satisfy formula (2) and therefore does not fall under the above-mentioned specific conjugated diene rubber) Conjugated diene rubbers 5 to 6: Conjugated diene rubbers 5 to 6 synthesized as described above (modified diene rubbers having a specific modifying group and which satisfy formulas (1) and (2) and therefore fall under the above-mentioned specific conjugated diene rubber) CB: SEAST 3 (HAF carbon black manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area (N ２ SA): 79m ２ / g) Silica: ZEOSIL 1165MP manufactured by Solvay (CTAB adsorption specific surface area: 160 m ２ / g) Silane coupling agent 1 (Si69): Si69 manufactured by Evonik. Bis(3-triethoxysilylpropyl)tetrasulfide Silane coupling agent 2 (NXT): A silane coupling agent having a thioester group. 3-octanoylthio-1-propyltriethoxysilane (structure shown below) (manufactured by Momentive Performance Materials) Silane coupling agent 3: A silane coupling agent having a polysiloxane skeleton and having a sulfide group and a mercapto group, represented by the following average composition formula: Average composition formula (-C ３ H ６ -S ４ -C ３ H ６ -) ０．０７１ (-C ８ H １７ ) ０．５７１ (-OC ２ H ５ ) １．５０ (-C ３ H ６ SH) ０．２８６ SiO０．７５ Silane coupling agent 3 was prepared as follows. 107.8 g (0.2 mol) of bis(triethoxysilylpropyl)tetrasulfide (KBE-846, manufactured by Shin-Etsu Chemical Co., Ltd.), 190.8 g (0.8 mol) of γ-mercaptopropyltriethoxysilane (KBE-803, manufactured by Shin-Etsu Chemical Co., Ltd.), 442.4 g (1.6 mol) of octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.), and 190.0 g of ethanol were placed in a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer. A mixed solution of 37.8 g (2.1 mol) of 0.5 N hydrochloric acid and 75.6 g of ethanol was then added dropwise at room temperature. The mixture was then stirred at 80°C for 2 hours. The mixture was then filtered, and 17.0 g of a 5% KOH / EtOH solution was added dropwise, followed by stirring at 80°C for 2 hours. The mixture was then concentrated under reduced pressure and filtered to obtain 480.1 g of a brown, transparent liquid polysiloxane. Measurement by GPC revealed that the average molecular weight was 840 and the average degree of polymerization was 4.0 (set degree of polymerization: 4.0). Furthermore, measurement of the mercapto equivalent by the acetic acid / potassium iodide / potassium iodate addition-sodium thiosulfate solution titration method revealed that it was 730 g / mol, confirming that the mercapto group content was as set. From the above, the obtained polysiloxane is represented by the following average compositional formula. Therefore, the obtained polysiloxane corresponds to the sulfur-containing silane coupling agent represented by the above-mentioned average compositional formula (X). (-C ３ H ６ -S ４ -C ３ H ６ -) ０．０７１ (-C ８ H １７ ) ０．５７１ (-OC ２ H ５ ) １．５０ (-C ３ H ６ SH) ０．２８６ SiO ０．７５The obtained polysiloxane is also referred to as silane coupling agent 3. Alkyltriethoxysilane: octyltriethoxysilane (KBE-3083, manufactured by Shin-Etsu Chemical Co., Ltd.) Process oil: Extract No. 4S manufactured by Showa Shell Sekiyu K.K. Thermoplastic resin 1: terpene-based resin. YS Resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatic modified terpene resin, softening point: 125°C) Thermoplastic resin 2: C5 / C9-based resin. RD104 manufactured by ENEOS Vulcanization accelerator (CZ): Sancerer CM-G (sulfenamide-based) manufactured by Sanshin Chemical Industry Co., Ltd. Vulcanization accelerator (DPG): Soxinol D-G (guanidine-based) manufactured by Sumitomo Chemical Co., Ltd. Sulfur: Myucron OT-20 manufactured by Shikoku Chemical Industry Co., Ltd.

[0134] As can be seen from Tables 3 and 4, all of Examples 1 to 14, which contained a diene rubber containing a specific amount of specific conjugated diene rubber, silica, a silane coupling agent, and an alkyltriethoxysilane, exhibited excellent rolling performance, wet performance, abrasion resistance, and aging resistance. Comparing Examples 1 and 2 (comparisons between embodiments that differ only in the type of rubber component), Example 1, which contained conjugated diene rubber 5 as the specific conjugated diene rubber, exhibited better abrasion resistance. Example 2, which contained conjugated diene rubber 6 as the specific conjugated diene rubber, exhibited better wet performance and heat aging resistance. Furthermore, comparing Example 1 and Example 3 (comparisons between embodiments that differ only in the content of the rubber component), Example 1, in which the proportion of the specific conjugated diene rubber in the diene rubber was 50% by mass or more, exhibited better rolling performance, wet performance, and heat aging resistance. Furthermore, comparing Examples 1 and 4 (comparison between embodiments differing only in the amount of silane coupling agent), Example 1, which contained a large amount of silane coupling agent, showed better abrasion resistance. Furthermore, comparing Example 1 with Examples 7 to 9, and comparing Example 5 with Examples 10 to 12 (comparison between embodiments differing only in the inclusion of a thermoplastic resin), Examples 7 to 9, which further contained a thermoplastic resin, showed at least better wet performance than Example 1, and Examples 10 to 12 than Example 5. Furthermore, comparing Examples 1, 5 to 6 (comparison between embodiments differing only in the type of silane coupling agent), Example 5, in which the silane coupling agent contained NXT, showed better aging resistance than Examples 1 and 6. Comparing Examples 7 to 9 with Examples 10 to 12 (comparison between embodiments differing only in the type of silane coupling agent), when a thermoplastic resin was further contained, Examples 10 to 12, in which the silane coupling agent contained NXT, exhibited better rolling performance and wet performance than Examples 7 to 9. Comparing Examples 13, 10, and 14 (comparison between embodiments differing only in the amount of alkyltriethoxysilane), Example 10 exhibited better rolling performance, wet performance, wear resistance, and aging resistance than Example 13, and better wear resistance and aging resistance than Example 14.

[0135] On the other hand, the standard example and comparative examples 1 to 3, which contain a modified diene rubber other than the specific conjugated diene rubber instead of the specific conjugated diene rubber, comparative example 4, which contains the specific conjugated diene rubber but does not contain alkyltriethoxysilane, and comparative example 5, in which the content of the specific conjugated diene rubber in the diene rubber is less than 25% by mass, were insufficient in at least one of rolling performance, wet performance, wear resistance, and aging resistance.

[0136] REFERENCE SIGNS LIST 1 Bead portion 2 Sidewall portion 3 Tire tread portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims

1. A rubber composition for tires, comprising a diene rubber containing a modified conjugated diene rubber (A1), silica, a silane coupling agent, and an alkyltriethoxysilane, the modified conjugated diene rubber (A1) being a conjugated diene rubber that satisfies the following formulas (1) and (2) and has a modifying group that contains a nitrogen atom, a silicon atom, and an oxygen atom adjacent thereto, the proportion of the modified conjugated diene rubber (A1) in the diene rubber being 25 mass% or more. IVw １０％ ≦3.1×10 －６ ×Mw １０％ -2.77 (1) IVw １０％ <4.7 (2) IVw in formula (1) and formula (2) １０％ and Mw in formula (1) １０％ The weight average molecular weight (Mw) is calculated by using the high molecular weight portion of the peak of the chromatogram obtained by the differential refractive index detector, which is 10% of the total area of ​​the peak. １０％ The weight-average intrinsic viscosity determined using the high molecular weight portion of the peak in the chromatogram obtained by the viscosity detector, which is 10% of the total peak area, is defined as IVw １０％ Here, the unit of the weight average intrinsic viscosity is dL / g.

2. The rubber composition for tires according to claim 1, wherein the modified conjugated diene rubber (A1) has a star structure with three or more branches, at least one branch of the star structure has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety has a further main chain branch structure.

3. A rubber composition for tires according to claim 1 or 2, further comprising a modified conjugated diene rubber (A2) other than the modified conjugated diene rubber (A1), wherein the total proportion of the modified conjugated diene rubber (A1) and the modified conjugated diene rubber (A2) in the diene rubber is 70 mass% or more.

4. The Mw １０％ is 2.0 x 10 ６ The rubber composition for tires according to any one of claims 1 to 3.

5. The rubber composition for tires according to any one of claims 1 to 4, wherein the content of said silica is 50 parts by mass or more per 100 parts by mass of said diene rubber.

6. The rubber composition for tires according to any one of claims 1 to 5, wherein the silane coupling agent contains 3-octanoylthio-1-propyltriethoxysilane or a sulfur-containing silane coupling agent represented by the following average composition formula (X), and the content of the silane coupling agent is 2 to 20 mass % of the content of the silica. (A) ａ (B) ｂ (C) ｃ (D) ｄ (R １ ) ｅ SiO （４－２ａ－ｂ－ｃ－ｄ－ｅ） In formula (X), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R １ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, and a to e satisfy the relational expressions 0≦a<1, 0<b<1, 0<c<3, 0<d<1, 0≦e<2, 0<2a+b+c+d+e<4.

7. The rubber composition for tires according to any one of claims 1 to 6, further comprising a thermoplastic resin, the thermoplastic resin comprising at least one selected from the group consisting of terpene resins, C5 / C9 resins, C9 resins, DCPD resins, DCPD / C9 resins, hydrogenated C5 / C9 resins, hydrogenated C9 resins, hydrogenated DCPD resins, and hydrogenated DCPD / C9 resins.

8. The rubber composition for tires according to any one of claims 1 to 7, further comprising a thermoplastic resin, the thermoplastic resin including at least two resins selected from the group consisting of terpene resins, C5 / C9 resins, C9 resins, DCPD resins, DCPD / C9 resins, hydrogenated C5 / C9 resins, hydrogenated C9 resins, hydrogenated DCPD resins, and hydrogenated DCPD / C9 resins.

9. A tire manufactured using the rubber composition for tires according to any one of claims 1 to 8.

Images