Rubber composition for tires and tires

Abstract

The present invention addresses the problem of providing: a rubber composition for tires which exhibits excellent processability and gives tires exhibiting excellent rolling performance, wet performance, wear resistance, and chipping resistance; and a tire produced using the rubber composition for tires. This rubber composition for tires comprises a rubber component (A) including a modified conjugated-diene rubber (A1), silica (B), and a silane coupling agent (C), wherein the A1 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 A1 in the A is 25 mass% or higher, and the C is 3-octanoylthio-1-propyltriethoxysilane or a polysiloxane represented by a specific average empirical formula.

Description

Technical Field

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

Background Art

[0002] Conventionally, a rubber composition for tires containing silica has been known from the viewpoint of improving performance (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Recently, from the viewpoints of safety and the like, further improvements in wet performance, snow performance, wear resistance, etc. have been demanded for tires. In addition, further improvements in mixing processability and extrusion processability have also been demanded for the rubber composition for tires for manufacturing tires. Under such circumstances, when the present inventors examined the rubber composition for tires described in Patent Document 1 and the like, it became clear that further improvement is desirable in consideration of the increasing demands in the future.

[0005] Therefore, in view of the above circumstances, the present invention provides a rubber composition for tires that exhibits excellent processability and excellent rolling performance, wet performance, wear resistance, and chipping resistance when formed into a tire, and a tire manufactured using the above rubber composition for tires.

Means for Solving the Problems

[0006] As a result of diligent research into the above-mentioned problems, the inventors of this invention discovered that the above-mentioned problems can be solved by using a specific modified conjugated diene rubber as the rubber component and a specific silane coupling agent, leading to the present invention. In other words, the inventors have found that the above problem can be solved by the following configuration.

[0007] (1) A rubber component (A) containing a modified conjugated diene rubber (A1), silica (B), and a silane coupling agent (C), The above modified conjugated diene rubber (A1) is a conjugated diene rubber that satisfies the following formulas (1) to (3) and has a modifying group containing a nitrogen atom, a silicon atom and an adjacent oxygen atom. The proportion of the above-mentioned modified conjugated diene rubber (A1) in the above-mentioned rubber component (A) is 25% by mass or more. A rubber composition for tires in which the above-mentioned silane coupling agent (C) is 3-octanoylthio-1-propyltriethoxysilane or a polysiloxane represented by the average composition formula of the following formula (C2). IVw 10% ≤3.1 × 10 -6 ×Mw 10% -2.77 (1) St + Vn ≤ 50 (2) IVw 10% <4.7 (3) Mw in equations (1) and (3) 10% and IVw 10% The details are as follows: Gel permeation chromatography measurements were performed on modified conjugated diene rubbers using a differential refractive index detector and a viscosity detector. The weight-average molecular weight (Mw) was determined using the high molecular weight portion of the chromatogram peaks, which accounted for 10% of the total peak area. 10% Furthermore, the weight-average intrinsic viscosity IVw is determined using the high molecular weight portion of the chromatogram peaks obtained by the viscosity detector, which accounts for 10% of the total peak area. 10% Let's assume that the unit of weight-average intrinsic viscosity is dL / g. In formula (2), St represents the proportion (mass %) of the repeating unit derived from styrene with respect to the total amount of the modified conjugated diene rubber, and Vn represents the proportion (mass %) of the repeating unit of the 1,2-vinyl structure derived from the conjugated diene with respect to the total amount of the modified conjugated diene rubber. (A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e) / 2 (C2) In formula (C2), 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. a to e satisfy the relational expressions of 0 ≦ a < 1, 0 < b < 1, 0 < c < 3, 0 < d < 1, 0 ≦ e < 2, and 0 < 2a + b + c + d + e < 4. (2) The modified conjugated diene rubber (A1) has a star structure with three or more branches, and at least one branch chain of the star structure has a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and in the above portion, has a further main chain branch structure, the tire rubber composition according to (1) above. (3) The content of the reinforcing filler containing the silica is 50 parts by mass or more with respect to 100 parts by mass of the rubber component (A), the tire rubber composition according to (1) or (2) above. (4) Further, contains a thermoplastic resin (D), the tire rubber composition according to any one of (1) to (3) above. (5) The thermoplastic resin (D) 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, (6) The thermoplastic resin (D) includes at least two 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. The tire rubber composition according to (4) or (5) above, wherein the total content of the thermoplastic resin (D) is 50 parts by mass or less per 100 parts by mass of the rubber component (A). (7) A tire manufactured using any of the tire rubber compositions described in (1) to (6) above. [Effects of the Invention]

[0008] As shown below, the present invention provides a tire rubber composition that exhibits excellent processability and, when made into a tire, excellent rolling performance, wet performance, wear resistance, and chipping resistance, as well as a tire manufactured using the above tire rubber composition. [Brief explanation of the drawing]

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

[0010] The rubber composition for tires and the like of the present invention will be described below. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. Furthermore, each component may be used alone or in combination of two or more. When two or more components are used in combination, the "content" of each component refers to the total content unless otherwise specified. Furthermore, with respect to rubber compositions for tires, the rolling performance, wet performance, abrasion resistance, and chipping resistance when made into tires are also simply referred to as "rolling performance," "wet performance," "abrasion resistance," and "chipping resistance," respectively. Furthermore, in this specification, powers of 10 may be represented by E. For example, E+5 represents 10 to the power of 5.

[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 It contains a rubber component (A) including a modified conjugated diene rubber (A1), silica (B), and a silane coupling agent (C). The above-mentioned modified conjugated diene rubber (A1) is a conjugated diene rubber that satisfies formulas (1) to (3) described later and has a modifying group containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom. The proportion of the above-mentioned modified conjugated diene rubber (A1) in the above-mentioned rubber component (A) is 25% by mass or more. The above silane coupling agent (C) is 3-octanoylthio-1-propyltriethoxysilane, or a polysiloxane represented by the average composition formula (C2) described later, in this tire rubber composition.

[0012] Because the composition of the present invention has such a configuration, it is believed that it can solve the problems described above. The reason for this is not clear, but it is presumed to be as follows. The composition of the present invention includes a conjugated diene rubber (hereinafter also referred to as "specific conjugated diene rubber") as a rubber component, which satisfies formulas (1) to (3) described later and has a modifying group (hereinafter also referred to as "specific modifying group") containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom. 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 from the inventors' studies, it has been found that rubbers satisfying formulas (1) and (3) have extremely excellent processability. Furthermore, it is thought that the specific modifying group of the specific conjugated diene rubber interacts with silica. In addition, the specific silane coupling agent contained in the composition of the present invention interacts with silica together with the above-mentioned specific modifying group, and further interacts with the skeleton of the specific conjugated diene rubber and other rubber components. Therefore, the dispersibility of silica in the composition of the present invention is extremely high, which is thought to lead to excellent effects (rolling performance, wet performance, abrasion resistance, chipping resistance).

[0013] The following describes each component contained in the composition of the present invention.

[0014] [1] Rubber component The composition of the present invention contains a rubber component that includes a specific conjugated diene rubber. The composition of the present invention may contain rubber components other than specific conjugated diene rubbers.

[0015] [Specific conjugated diene rubber] The specified conjugated diene rubber is a conjugated diene rubber that satisfies formula (1) and formula (2) described later, and has a modified group (specified modified group) containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom.

[0016] [Body structure] The backbone of specific conjugated diene rubbers is a polymer having repeating units derived from conjugated dienes.

[0017] <Conjugated Diene> Specific examples of conjugated dienes include butadiene (especially 1,3-butadiene), isoprene, and chloroprene. The above dienes are preferably butadiene (especially 1,3-butadiene) or isoprene, and more preferably butadiene (especially 1,3-butadiene), for the reasons that the effects of the present invention are superior.

[0018] <Other monomers> The backbone of a specific conjugated diene rubber may have repeating units other than those derived from the conjugated diene. Examples of monomers that form such repeating units (other monomers) include vinyl monomers and alkenes (e.g., ethylene, propylene, butene). Examples of vinyl monomers include aromatic vinyls (e.g., styrene), acrylonitrile, and specific branching agents described later.

[0019] <Specific example> Specific examples of the skeleton 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 above-mentioned conjugated diene rubber is preferably SBR because it provides superior effects for the present invention.

[0020] [Specific modified group] As described above, specific conjugated diene rubbers have a nitrogen atom, a silicon atom, and a modified group (specific modified group) that contains an oxygen atom adjacent to the silicon atom. The specific modifying group may be located at the end, main chain, or side chain of the conjugated diene rubber. The specific modified group preferably contains a silicon atom and an adjacent oxygen atom as an alkoxysilyl group, for better performance of the present invention. Note that the alkoxysilyl group is -Si(OR1) n(R2) 3-n This is a group represented as (where R1: alkyl group, R2: hydrogen atom or alkyl group, n: integer from 1 to 3). The specific modified group preferably contains a nitrogen atom as an amino group (primary to tertiary amino group) because this provides superior effects for the present invention. The specific modifying group is preferably a group derived from a specific modifying agent described later, for the reason that the effects of the present invention are superior.

[0021] [Formula (1)] The specified conjugated diene rubber satisfies the following formula (1). Equation (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. Polymers with branching or other characteristics that result in small molecular size relative to their molecular weight tend to satisfy equation (1). The reason for limiting the equation to the high molecular weight side is that it has a significant impact on the overall properties of the polymer.

[0022] IVw 10% ≤3.1 × 10 -6 ×Mw 10% -2.77 (1)

[0023] Mw in equation (1) 10% and IVw 10% It can be calculated as follows. Gel permeation chromatography measurements were performed on modified conjugated diene rubbers using a differential refractive index detector (RI detector) and a viscosity detector. The weight-average molecular weight (Mw) was determined using the high molecular weight portion of the chromatogram peaks, which accounted for 10% of the total peak area. 10% Furthermore, the weight-average intrinsic viscosity IVw is determined using the high molecular weight portion of the chromatogram peaks obtained by the viscosity detector, which accounts for 10% of the total peak area. 10% Let's assume that the unit of weight-average intrinsic viscosity is dL / g.

[0024] Below, in equation (1) Mw 10% and IVw 10% I will explain this in more detail.

[0025] As described above, gel permeation chromatography (GPC) measurements will be performed on modified conjugated diene rubbers using a differential refractive index detector and a viscosity detector. The specific method for GPC measurement is as follows.

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

[0027] The weight-average molecular weight is determined using the high molecular weight side (shorter elution time) portion of the peak (peak originating from modified conjugated diene rubber) of the chromatogram obtained by a differential refractive index detector (horizontal axis: elution time, vertical axis: signal intensity), which accounts for 10% of the total peak area. The obtained weight-average molecular weight is then expressed as Mw 10% Let's assume that.

[0028] Furthermore, the weight-average intrinsic viscosity is determined using the portion of the chromatogram obtained from the viscosity detector (horizontal axis: elution time, vertical axis: signal intensity) that represents 10% of the total area of ​​the peak (the high molecular weight side, where the elution time is shorter). The obtained weight-average intrinsic viscosity is then expressed as IVw. 10% Let's assume that. Weight-average intrinsic viscosity is defined as (Σ(ηi×Mi×Ni)) / (Σ(Mi×Ni)) where the molecular weight Mi is equal to the number of molecules Ni and the intrinsic viscosity is ηi.

[0029] Figure 1 shows an example of a GPC chromatogram (horizontal axis: elution time, vertical axis: signal intensity). Using P1, which is the high molecular weight side (shorter elution time) portion that accounts for 10% of the area of ​​the entire peak P0, Mw10% and IVw 10% We seek.

[0030] Methods for making the modified conjugated diene rubber satisfy formula (1) include, for example, changing the type and amount of specific modifying agent and the type and amount of specific branching agent in the manufacturing method of the present invention described later.

[0031] Mw 10% For reasons that the effects of the present invention are superior, the value is preferably 100,000 to 10,000,000, and more preferably 1,000,000 to 5,000,000.

[0032] [Formula (2)] The specified conjugated diene rubber satisfies the following formula (2).

[0033] St + Vn ≤ 50 (2)

[0034] In formula (2), St represents the proportion (mass%) of repeating units derived from styrene to the total specific conjugated diene rubber (hereinafter also referred to as "styrene amount"), and Vn represents the proportion (mass%) of repeating units of a 1,2-vinyl structure derived from a conjugated diene (e.g., butadiene) to the total specific conjugated diene rubber (hereinafter also referred to as "vinyl amount").

[0035] St+Vn is preferably 10 to 45, and more preferably 25 to 45, for better effects of the present invention.

[0036] St is preferably 5 to 40, more preferably 10 to 35, and even more preferably 15 to 30, for better effects of the present invention.

[0037] Vn is preferably 5 to 30, and more preferably 10 to 20, for better effects of the present invention.

[0038] [Formula (3)] The specified conjugated diene rubber satisfies the following formula (3). IVw 10% <4.7(3)

[0039] IVw 10% The method for finding it is as described above.

[0040] IVw 10% For reasons that the effects of the present invention are superior, the value is preferably 1 to 4.6, and more preferably 2 to 4.4.

[0041] [Molecular weight] The weight-average molecular weight (Mw) of the specific conjugated diene rubber is preferably 100,000 to 2,000,000, and more preferably 200,000 to 1,300,000, for the reasons that the effects of the present invention are superior. Furthermore, the method for measuring the weight-average molecular weight (Mw) of specific conjugated diene rubbers is the same as described above, except that the entire peak is used. 10% It is the same as this.

[0042] [Glass transition temperature] The glass transition temperature (Tg) of the specific conjugated diene rubber is not particularly limited, but it is preferably -100°C to -30°C, and more preferably -80°C to -45°C, for better effects of the present invention. The glass transition temperature can be adjusted, for example, by controlling the amount of styrene or vinyl. In this specification, the glass transition temperature (Tg) is calculated using the midpoint method after measuring it with a differential scanning calorimeter (DSC) at a heating rate of 10°C / min.

[0043] [Preferred Embodiment 1] The specific conjugated diene rubber is preferably having a star-shaped structure with three or more branches, more preferably having a star-shaped structure with three or more branches with a specific modifying group as a branching point, and even more preferably being a conjugated diene rubber represented by the following formula (A).

[0044] [ka]

[0045] In formula (A), X represents an n-valent group (specifically modified group) containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom, P represents a conjugated diene polymer chain, and n represents an integer of 3 or more.

[0046] As described above, X represents an n-valent group (specifically modified group) containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom. For reasons that the effects of the present invention are superior, X preferably contains a silicon atom and an adjacent oxygen atom as an alkoxysilyl group. For reasons that the effects of the present invention are superior, it is preferable that X contains a nitrogen atom as an amino group.

[0047] As mentioned above, P represents a conjugated diene polymer chain. Multiple Ps may be the same or different. The definition, specific examples, and preferred embodiments of conjugated diene polymer chains are the same as those for the specific conjugated diene rubber skeleton described above.

[0048] As described above, n represents an integer of 3 or greater. There is no particular upper limit to n, but it is preferable that n be 30 or less for the sake of superior effects of the present invention.

[0049] [Preferred Embodiment 2] When a specific conjugated diene rubber has a star-shaped structure with three or more branches, it is preferable that at least one branched chain (conjugated diene polymer chain) of the star-shaped structure has a portion derived from a specific branching agent described later, and that this portion has a further main chain branching structure, for reasons that the effects of the present invention are superior. A main chain branched structure refers to a structure in which a branched chain (a conjugated diene polymer chain) forms branching points at a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and further polymer chains (for example, another conjugated diene polymer chain) extend from these branching points.

[0050] [Content] The proportion of specific conjugated diene rubber in the rubber component is 25% by mass or more. The above proportion is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, for the sake of superior effects of the present invention. There is no particular upper limit to the above percentage, which is 100% by mass.

[0051] [Method for manufacturing specific conjugated diene rubber] The method for producing specific conjugated diene rubber is not particularly limited, but a method comprising the following steps (1) to (2) (hereinafter also referred to as the "production method of the present invention") is preferred for the reason that the effects of the present invention are superior. (1) Polymerization step to obtain a conjugated diene polymer by polymerizing a monomer containing a conjugated diene by anionic polymerization. (2) Modification step: A conjugated diene polymer obtained in the polymerization step is reacted 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 modifier group.

[0052] [Polymerization process] The polymerization process involves polymerizing monomers containing conjugated dienes by anionic polymerization to obtain conjugated diene polymers.

[0053] <Anionic polymerization> Anionic polymerization is not particularly limited, but it is preferable to use an organolithium compound as an initiator for better effects of the present invention.

[0054] The organolithium compounds are not particularly limited, but specific examples include monoorganolithium compounds such as n-butyllithium (n-BuLi), sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene. Among these, monoorganolithium compounds of n-butyllithium, sec-butyllithium, and tert-butyllithium are preferred, and n-butyllithium is more preferred, for the reason that the effects of the present invention are superior.

[0055] The amount of organolithium compound used is not particularly limited, but it is preferably 0.001 to 10 mol% relative to the monomer, for better effects of the present invention.

[0056] <Monomer> Specific examples and preferred embodiments of monomers containing conjugated dienes used in the polymerization process are the same as the conjugated dienes and other monomers in the backbone of the specific conjugated diene rubber described above.

[0057] (Specific branching agent) The monomer preferably contains a vinyl monomer (hereinafter also referred to as "specific branching agent") that includes an alkoxysilyl group or a halosilyl group, for the reason that the effects of the present invention are superior. 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, for reasons that the effects of the present invention are superior.

[0058] (1) Specific examples Specific examples of aromatic vinyls containing alkoxysilyl groups include 1-(trimethoxysilyl)-4-vinylbenzene and 1,1-bis(4-trimethoxysilylphenyl)ethylene. Furthermore, examples of aromatic vinyls containing a halosilyl group include trichloro(4-vinylphenyl)silane and 1,1-bis(4-trichlorosilylphenyl)ethylene.

[0059] (2) Usage amount The amount of specific branching agent used is preferably 0.001 to 0.1% by mass, and more preferably 0.005 to 0.05% by mass, relative to the conjugated diene, for better performance of the present invention.

[0060] <Polar compounds> Polar compounds may be added during the polymerization process. This allows for random copolymerization of monomers. Furthermore, polar compounds tend to be used as vinylizing agents to control the microstructure of conjugated dienes. They also tend to be effective in accelerating polymerization reactions.

[0061] 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-butyrate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used individually or in combination of two or more.

[0062] (Amount used) For optimal results of the present invention, the amount of polar compound used is preferably 0.01 moles or more and 100 moles or less per mole of initiator.

[0063] [Modification process] The modification step involves reacting the conjugated diene polymer obtained in the polymerization step with a modifying agent (specific modifying agent) containing nitrogen atoms, silicon atoms, and adjacent oxygen atoms to obtain a conjugated diene rubber having a specific modifying group.

[0064] In the modification process, it is thought that the active ends of the conjugated diene polymer obtained in the polymerization process bond to the silicon atoms of the specific modifying agent. For example, if the specific modifying agent contains an alkoxysilyl group, it is thought that the active ends bond to the silicon atoms of the alkoxysilyl group, and the alkoxy group is removed. Furthermore, if the conjugated diene polymer obtained in the polymerization process contains a portion derived from a specific branching agent, it is thought that, in addition to the active end mentioned above, the alkoxysilyl or halosilyl group of that portion also reacts with the specific modifying agent (e.g., an alkoxysilyl group). It is also thought that the alkoxysilyl or halosilyl group of that portion reacts with the active end of another conjugated diene polymer. As a result, the conjugated diene polymer containing a portion derived from a specific branching agent will have a main chain branched structure (another conjugated diene polymer chain) in that portion.

[0065] <Specific Modifying Agent> The specific denaturing agent is a compound containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom. For reasons that the effects of the present invention are superior, the specific modifying agent is preferably a group containing an alkoxysilyl group (particularly a trialkoxysilyl group) or a silazane structure (particularly a cyclic silazane structure), wherein the silicon atom and the oxygen atom adjacent to it are bonded to an alkoxy group. Here, a silazane structure refers to a structure in which a silicon atom and a nitrogen atom are directly bonded (a structure having a Si-N bond). For reasons that the effects of the present invention are superior, the specific modifying agent preferably contains a nitrogen atom as a group including an amino group (primary to tertiary amino group) or a silazane structure (particularly a cyclic silazane structure). The specific modifying agent preferably has two or more (preferably three or more) sites that can react with active ends such as alkoxysilyl groups. When the specific modifying agent has multiple such sites, it functions as a coupling agent that connects conjugated diene polymers.

[0066] (Specific example) Specific examples of specific denaturants include tertiary amines having alkoxysilyl groups such as tris(3-trimethoxysilylpropyl)amine and tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, cyclic silazanes having alkoxysilyl groups such as 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, tertiary amines containing alkoxysilyl group-containing cyclic silazane structures 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, and bis[3 Examples include 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]-1,3-propanediamine, and bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine.

[0067] (Amount used) The amount of specific denaturing agent used is preferably 0.01 to 1% by mass, and more preferably 0.02 to 0.2% by mass, relative to the conjugated diene, for better performance of the present invention.

[0068] [Other processes] The manufacturing method of the present invention may include steps other than those described above (other steps). Other steps include a polymerization termination step in which a polymerization inhibitor (e.g., methanol) is added, and a solvent removal step in which the solvent is removed by steam stripping.

[0069] [Other rubber components] The rubber component may contain rubber components other than specific conjugated diene rubbers. Examples of such other rubber components 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 rubbers include styrene-butadiene rubber (SBR) and styrene-isoprene copolymer rubber. The rubber component preferably contains SBR for better effects of the present invention. When the rubber component contains SBR, the proportion of SBR in the rubber component is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, for better effects of the present invention. The rubber component preferably contains BR for better effects of the present invention. When the rubber component contains BR, the proportion of BR in the rubber component is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, for better effects of the present invention. The rubber component preferably contains natural rubber for better effects of the present invention. When the rubber component contains natural rubber, the proportion of natural rubber in the rubber component is preferably 1 to 30% by mass, and more preferably 5 to 20% by mass, for better effects of the present invention.

[0070] [Average Tg] The glass transition temperature of the entire rubber component (hereinafter also referred to as "average Tg") is preferably greater than -80°C and less than or equal to -45°C, and more preferably between -75°C and less than or equal to -45°C, for the sake of superior effects of the present invention. Note that the average Tg of the rubber components is the sum of the glass transition temperatures (Tg) of each rubber component multiplied by the mass fraction of each rubber component (weighted average of glass transition temperatures).

[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. The silica is not particularly limited, and any conventionally known silica can be used. Examples of silica include wet silica, dry silica, fumed silica, and diatomaceous earth. Biomass-derived silica, such as rice husks, may also be used. The above silica may be used alone or in combination of two or more types.

[0073] [CTAB] The specific surface area of ​​silica adsorbing cetyltrimethylammonium bromide (CTAB) (hereinafter, "CTAB adsorption specific surface area" will also be simply referred to as "CTAB") is not particularly limited, but for reasons of superior effectiveness in the present invention, 100 to 300 m is preferred. 2 It is preferable that the amount be / g, and 150-200m 2 It is more preferable that it be / g. Here, the CTAB adsorption specific surface area is the value measured in accordance with JIS K6430:2008 Annex G.

[0074] [Content] In the composition of the present invention, the content of silica is preferably 30 to 150 parts by mass, more preferably 50 to 100 parts by mass, based on 100 parts by mass of the rubber component described above, because the effects of the present invention are more excellent.

[0075] [3] Specific silane coupling agent The composition of the present invention contains 3 - octanoylthio - 1 - propyltriethoxysilane, or a polysiloxane represented by the average composition formula of formula (C2) described below (hereinafter, collectively referred to as "specific silane coupling agent").

[0076] [3 - octanoylthio - 1 - propyltriethoxysilane] 3 - octanoylthio - 1 - propyltriethoxysilane is a compound represented by the following structural formula.

[0077]

Chemical formula

[0078] [Specific polysiloxane] Hereinafter, the polysiloxane represented by the average composition formula of formula (C2) (hereinafter, also referred to as "specific polysiloxane") will be described. The specific polysiloxane is a polysiloxane represented by the average composition formula of the following formula (C2). (A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e) / 2 (C {2})

[0079] In the above formula (C2), 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. a to e satisfy the relational expressions of 0 ≤ a < 1, 0 < b < 1, 0 < c < 3, 0 < d < 1, 0 ≤ e < 2, and 0 < 2a + b + c + d + e < 4.

[0080] Formula (C2) represents the average composition of polysiloxane. That is, it represents the types of groups directly bonded to the Si atoms of the polysiloxane, and the average number of each group. In formula (C2), Si represents the Si atom of polysiloxane. Also, O in formula (C2) represents the O atom of polysiloxane. Note that the O atom is a divalent group and always bonds to two Si atoms (Si atoms of polysiloxane). In formula (C2), (4-2a-bcde) / 2 represents the average number of polysiloxane O atoms that bond to the Si atoms of polysiloxane. A, B, C, D and R in formula (C2) 1 All of these represent groups that bond to the Si atoms of polysiloxane. Note that A is a divalent group and always bonds to two Si atoms (the Si atoms of polysiloxane). In formula (C2), a, b, c, d, and e are A, B, C, D, and R which bond to the Si atoms of polysiloxane, respectively. 1 This represents the average number. As can be seen from the fact that the sum of the groups directly bonded to the Si atom of polysiloxane (a×2+b+c+d+e+((4-2a-bcde) / 2)×2) is 4 (valence of the Si atom), the Si atom of polysiloxane has A, B, C, D, R 1 Groups other than A and O do not bond directly. Note that in the above calculation of the total, a and (4-2a-bcde) / 2) are doubled because A and O are divalent groups.

[0081] Specific examples and preferred embodiments of specific polysiloxanes and methods for producing the same are described in paragraphs

[0038] to

[0070] of Japanese Patent Application Publication No. 2019-156918, paragraphs

[0020] to

[0050] of International Publication No. 2014 / 129664, and paragraphs

[0046] to

[0099] of U.S. Patent Application Publication No. 2016 / 0002433, which are incorporated by reference.

[0082] [Content] In the composition of the present invention, the content of the specific silane coupling agent is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferably 2 to 20 parts by mass, and more preferably 5 to 15 parts by mass, per 100 parts by mass of the rubber component described above.

[0083] Furthermore, in the composition of the present invention, the content of the specific silane coupling agent is preferably 1 to 20% by mass, and more preferably 5 to 15% by mass, relative to the silica content, for the reason that the effects of the present invention are superior.

[0084] Furthermore, in the composition of the present invention, the content of the specific silane coupling agent is preferably 10 to 30% by mass relative to the content of the specific conjugated diene rubber described above, for the reason that the effects of the present invention are superior.

[0085] [4] Optional component The composition of the present invention may optionally contain components other than those described above (optional components). Examples of such components include various additives commonly used in rubber compositions, such as reinforcing fillers other than silica (preferably carbon black), silane coupling agents other than specific silane coupling agents, thermally expandable microcapsules, zinc oxide, stearic acid, antioxidants, waxes, processing aids, liquid polymers, thermoplastic resins, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators, and vulcanization activators.

[0086] [Thermoplastic resin] The composition of the present invention preferably contains a thermoplastic resin because it provides superior effects. The composition of the present invention preferably contains two or more thermoplastic resins for better performance of the present invention.

[0087] [Specific examples] Examples of thermoplastic resins include coumarone resins (e.g., coumarone resin, coumarone-indene resin, coumarone-indene-styrene resin), phenolic resins (e.g., phenolic resin, phenol-acetylene resin, phenol-formaldehyde resin), xylene resins (e.g., xylene resin, xylene-acetylene resin, xylene-formaldehyde resin), rosin resins (e.g., rosin, rosin ester, hydrogenated rosin derivative), and terpene resins (e.g., terpene resin, etc.). Examples include terpene resins (aromatically modified terpene resins, etc.), terpene phenol resins, hydrogenated terpene resins, α-pinene resins, β-pinene resins, limonene resins, hydrogenated limonene resins, dipentene resins, terpene styrene resins), styrene resins, petroleum resins (for example, C5 / C9 resins, C9 resins, DCPD (dicyclopentadiene) resins, DCPD / C9 resins, hydrogenated C5 / C9 resins, hydrogenated C9 resins, hydrogenated DCPD resins, hydrogenated DCPD / C9 resins), and aliphatic saturated hydrocarbon resins.

[0088] For reasons that the effects of the present invention are superior, 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 at least two selected from the above group.

[0089] [Content] In the composition of the present invention, the content of the thermoplastic resin is preferably 1 to 100 parts by mass, and more preferably 5 to 50 parts by mass, per 100 parts by mass of the rubber component described above, for the reason that the effects of the present invention are superior.

[0090] Furthermore, in the composition of the present invention, the content of the thermoplastic resin is preferably 5 to 100% by mass, more preferably 20 to 90% by mass, and even more preferably 30 to 60% by mass, relative to the specified conjugated diene rubber, for the reason that the effects of the present invention are superior.

[0091] [Carbon Black] The composition of the present invention preferably contains carbon black for better effects of the present invention. The carbon black may be one type of carbon black used alone, or two or more types of carbon black may be used in combination. The carbon black mentioned above is not particularly limited, and various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, and SRF can be used.

[0092] [N2SA] The nitrogen adsorption specific surface area (N2SA) of the carbon black described above is not particularly limited, but for the sake of superior effectiveness of the present invention, 50-200m² is preferred. 2 It is preferable that the value be / g, and 70-150m 2 It is more preferable that it be / g. Here, the nitrogen adsorption specific surface area (N2SA) is the value obtained by measuring the amount of nitrogen adsorbed onto the carbon black surface according to JIS K6217-2:2001 "Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single point method".

[0093] [Content] In the composition of the present invention, the carbon black content is not particularly limited, but for reasons that the effects of the present invention are superior, 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 rubber component described above.

[0094] [Reinforcing filler] In the composition of the present invention, the content of the reinforcing filler containing silica described above is preferably 50 parts by mass or more, more preferably 60 to 200 parts by mass, and even more preferably 70 to 150 parts by mass, per 100 parts by mass of the rubber component described above, for the reason that the effects of the present invention are superior. The carbon black described above is included in the reinforcing filler.

[0095] [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 include, for example, a method of kneading each of the above-mentioned components using known methods and equipment (e.g., Banbury mixer, kneader, roll, etc.). If the composition of the present invention contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than sulfur and the vulcanization accelerator at a high temperature (preferably 100 to 160°C), cool them, and then mix in the sulfur or vulcanization accelerator. Furthermore, the compositions of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0096] [II] Tires 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, and other gases.

[0097] Figure 2 shows a schematic partial cross-sectional view of a tire representing an example of an embodiment of the tire of the present invention. However, the tire of the present invention is not limited to the embodiment shown in Figure 2.

[0098] In Figure 2, reference numeral 1 represents the bead portion, reference numeral 2 represents the sidewall portion, and reference numeral 3 represents the tire tread portion. Furthermore, a carcass layer 4 with embedded fiber cords is installed between the pair of left and right bead sections 1, and the ends of this carcass layer 4 are folded back and wrapped around the bead core 5 and bead filler 6 from the inside to the outside of the tire. Furthermore, in the tire tread section 3, a belt layer 7 is arranged around the entire circumference of the tire, on the outside of the carcass layer 4. Furthermore, a rim cushion 8 is positioned in the bead portion 1 where it contacts the rim. Furthermore, at least one of reference numerals 2-3, 5-6, and 8 (preferably reference numeral 3) is formed by the composition of the present invention as described above.

[0099] The tire of the present invention can be manufactured, for example, by conventionally known methods. In addition to ordinary air or air with adjusted oxygen partial pressure, inert gases such as nitrogen, argon, and helium can be used as the gas to fill the tire. [Examples]

[0100] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0101] [Synthesis of conjugated diene rubbers] The following conjugated diene rubbers were synthesized.

[0102] [Conjugated diene rubber 1]

[0103] <Polymerization process> In an autoclave equipped with a stirrer, under a nitrogen atmosphere, cyclohexane was charged at a rate of 1000 g / h, tetramethylethylenediamine at 0.028 g / h, 1,3-butadiene at 189.4 g / h, 1-butene at 0.436 g / h, and styrene at 10.6 g / h. Then, n-butyllithium was continuously added at a rate of 1.43 mmol / h, and polymerization was started at 70°C. Once polymerization had stabilized sufficiently, 1-(trimethoxysilyl)-4-vinylbenzene (branching agent) was added at a rate of 0.07 g / h, and the reaction was carried out with stirring. The branching agent is the specific branching agent mentioned above.

[0104] <Modification process> To the solution that flowed out of the reactor outlet, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine (denaturant) was added at a rate of 0.33 g / h, and the mixture was stirred to allow the reaction to proceed.

[0105] Subsequently, methanol was added as a polymerization inhibitor to obtain a solution containing conjugated diene rubber.

[0106] To the obtained solution, 1.14 parts by mass of Irganox 1520L (manufactured by BASF) was added as an antioxidant per 100 parts by mass of conjugated diene rubber. The solvent was then removed by steam stripping, and the solution was vacuum-dried at 60°C for 24 hours to obtain solid conjugated diene rubber. The obtained conjugated diene rubber is also referred to as conjugated diene rubber 1.

[0107] Conjugated diene rubber 1 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, and a modifying agent. It is a modified conjugated diene rubber having modifying groups (specific modifying groups) containing nitrogen atoms, silicon atoms, and adjacent oxygen atoms derived from the modifying agent. The conjugated diene rubber 1 has a star-shaped structure with three or more branches, with a modifying group as the branching point. The branched chains bonded to the modifying group have a portion derived from a branching agent, and the portion derived from the branching agent has a further main chain branching structure (conjugated diene polymer chain).

[0108] [Conjugated diene rubber 2-4] Except for changing the amounts of each component used as shown in Table 1, a solid conjugated diene rubber was obtained following the same procedure as for conjugated diene rubber 1. The obtained conjugated diene rubbers are also referred to as conjugated diene rubbers 2 to 4.

[0109] Conjugated diene rubbers 2-4 are reaction products of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, and a modifying agent. They are modified conjugated diene rubbers that have modifying groups (specific modifying groups) containing nitrogen atoms, silicon atoms, and adjacent oxygen atoms, derived from the modifying agent. The conjugated diene rubbers 2-4 have a star-shaped structure with three or more branches, with a modifying group as the branching point. The branched chains bonded to the modifying group have a portion derived from the branching agent, and the portion derived from the branching agent has a further main chain branching structure (conjugated diene polymer chain).

[0110] [Comparatively conjugated diene rubber] To a nitrogen-purged 100 mL ampoule, cyclohexane (35 g) and tetramethylethylenediamine (1.4 mmol) were added, followed by the addition of n-butyllithium (4.3 mmol). Then, isoprene (21.6 g) and styrene (3.1 g) were slowly added, and the mixture was reacted in the ampoule at 50°C for 120 minutes to obtain a polymer block (A) with active ends. Next, cyclohexane (4000 g), 1,3-butadiene (474.0 g), and styrene (126.0 g) were charged into an autoclave with a stirrer under a nitrogen atmosphere. The entire amount of the polymer block (A) with active ends obtained above was then added, and polymerization was started at 50°C. After confirming that the polymerization conversion rate was in the range of 95% to 100%, a polyorganosiloxane represented by the following formula (11) was added in the form of a 20% by mass xylene solution so that the epoxy group content was 1.42 mmol (corresponding to 0.33 times the mole of n-butyllithium used), and the reaction was allowed to proceed for 30 minutes. Subsequently, methanol equivalent to 2 times the mole of n-butyllithium used was added as a polymerization inhibitor to obtain a solution containing conjugated diene rubber. A small amount of antioxidant (Irganox 1520, BASF) was added to this solution, and the solid rubber was recovered by steam stripping. The obtained solid rubber was dewatered using rollers and dried in a dryer to obtain solid conjugated diene rubber. The obtained conjugated diene rubber was designated as comparative conjugated diene rubber.

[0111] [ka]

[0112] In the above equation (11), X 1 , X 4 , R 1 ~R 3 and R 5 ~R 8 is a methyl group. In formula (11) above, m is 80 and k is 120. In formula (11) above, X 2 This is the group represented by the following formula (12) (where * represents the bond position).

[0113] [ka]

[0114] [Table 1]

[0115] [Weight-average molecular weight, weight-average intrinsic viscosity, styrene content, vinyl content, glass transition temperature] As described above, for the synthesized conjugated diene rubbers (conjugated diene rubbers 1-4, comparative conjugated diene rubber), Mw, Mw 10% , IVw, IVw 10% Table 2 shows the values ​​of St, Vn, and the glass transition temperature (Tg). Note that in Table 2, the "right-hand side" of equation (1) is "3.1 × 10 -6 ×Mw 10% This represents the value "-2.77". Furthermore, in Table 2, "Applicable or not applicable" in formula (1) indicates whether or not formula (1) is applicable. Specifically, "A" indicates that formula (1) is satisfied, and "B" indicates that formula (1) is not satisfied. Furthermore, in Table 2, "St+Vn" in equation (2) represents the St+Vn mentioned above.

[0116] [Table 2]

[0117] As shown in Table 2, all conjugated diene rubbers 1 and 2 satisfy formulas (1) to (3). Furthermore, as stated above, all conjugated diene rubbers 1 and 2 are modified conjugated diene rubbers having specific modifying groups. Therefore, all conjugated diene rubbers 1 and 2 fall under the category of specific conjugated diene rubbers as described above. On the other hand, as shown in Table 2, conjugated diene rubber 3 satisfies formulas (1) and (2) but does not satisfy formula (3), and therefore does not fall under the category of specified conjugated diene rubber as described above. Also, as shown in Table 2, conjugated diene rubber 4 satisfies formulas (1) and (3) but does not satisfy formula (2), and therefore does not fall under the category of specified conjugated diene rubber as described above. Furthermore, comparative conjugated diene rubber does not satisfy formulas (1) and (2), and therefore does not fall under the category of specified conjugated diene rubber as described above.

[0118] [Synthesis of polysiloxanes] In a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 107.8 g (0.2 mol) of bis(triethoxysilylpropyl) tetrasulfide (Shin-Etsu Chemical Co., Ltd., KBE-846), 190.8 g (0.8 mol) of γ-mercaptopropyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-803), 442.4 g (1.6 mol) of octyltriethoxysilane (Shin-Etsu Chemical Co., Ltd., KBE-3083), and 190.0 g of ethanol were placed. 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. After filtration, 17.0 g of 5% KOH / EtOH solution was added dropwise, and the mixture was stirred at 80°C for 2 hours. Subsequently, 480.1 g of a brown, transparent polysiloxane was obtained by vacuum concentration and filtration. GPC analysis revealed an average molecular weight of 840 and an average degree of polymerization of 4.0 (target degree of polymerization of 4.0). Furthermore, mercapto equivalents were measured using the acetic acid / potassium iodide / potassium iodate-sodium thiosulfate titration method, resulting in a value of 730 g / mol, confirming the target mercapto group content. Therefore, the average compositional formula is shown below. Thus, the obtained polysiloxane corresponds to the specified polysiloxane described above. (-C3H6-S4-C3H6-) 0.071 (-C8H 17 ) 0.571 (-OC2H5) 1.50 (-C3H6SH) 0.286 SiO 0.75 The resulting polysiloxane is also called silane coupling agent 2.

[0119] [Preparation of rubber compositions for tires] Each component in Tables 3-5 below was mixed in the composition (parts by mass) shown in the same table. Specifically, first, the components other than sulfur and vulcanization accelerator listed in Tables 3-5 were mixed in a 1.8 L sealed mixer at a temperature of 160°C or lower for 5 minutes, and the masterbatch was released. Then, sulfur and vulcanization accelerator were added to the masterbatch and mixed using an open roll at a temperature of 100°C or lower to produce each tire rubber composition.

[0120] [evaluation] The following evaluations were performed on each of the obtained tire rubber compositions.

[0121] [Rolling performance] Vulcanized rubber test specimens were prepared by vulcanizing each tire rubber composition at 170°C for 10 minutes using a mold of a predetermined shape (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm). For these vulcanized rubber test specimens, tanδ (60°C) was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under conditions of tensile deformation strain of 0.5 ± 2% and vibration frequency of 20 Hz. The rolling performance was evaluated using the reciprocal of this value. The results are shown in Tables 3-5. The results are expressed as an index with the standard example set to 100. A larger index indicates better rolling performance. In practical terms, an index greater than 100 is preferable.

[0122] [Wet performance] Vulcanized rubber test specimens were prepared by vulcanizing each tire rubber composition at 170°C for 10 minutes using a mold of a predetermined shape (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm). For these vulcanized rubber test specimens, tanδ (0°C) was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under conditions of tensile deformation strain of 0.5 ± 2% and vibration frequency of 20 Hz. This value was used to evaluate the wet performance. The results are shown in Tables 3-5. The results are expressed as an index, with the standard example set to 100. A higher index indicates better wet performance. In practical terms, an index greater than 100 is preferable.

[0123] [Workability] The Mooney viscosity of each tire rubber composition was measured at 100°C according to JIS K6300, and processability was evaluated using the reciprocal of this value. The results are shown as an index, with the standard value set to 100. A higher index indicates better processability. In practical terms, an index of 100 or higher is preferable.

[0124] [Abrasion resistance] Each tire rubber composition was vulcanized at 170°C for 10 minutes using a mold of a predetermined shape (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm) to prepare vulcanized rubber test specimens. Using these vulcanized rubber test specimens, dumbbell-shaped JIS No. 3 test specimens were prepared in accordance with JIS K6251. Tensile tests were performed on these specimens at room temperature (23°C) at a tensile speed of 500 mm / min to measure the tensile breaking strength. The evaluation results are recorded in the "Abrasion Resistance" column of Tables 3-5 as an index with the standard example value set to 100. A higher index indicates higher breaking strength and superior abrasion resistance. Note that for abrasion resistance, an index value of "100" indicates no improvement, while an index value of "102" or higher indicates excellent abrasion resistance.

[0125] [Chipping resistance] Each tire rubber composition was vulcanized at 170°C for 10 minutes using a mold of a predetermined shape (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm) to prepare vulcanized rubber test specimens. Using these vulcanized rubber test specimens, dumbbell-shaped JIS No. 3 test specimens were prepared in accordance with JIS K6251. Tensile tests were performed on these specimens at room temperature (23°C) at a tensile speed of 500 mm / min, and the tensile elongation at break was measured. The evaluation results are recorded in the "Chipping Resistance" column as an index with the standard example value set to 100. A higher index indicates higher elongation at break and superior chipping resistance. In practical terms, a value greater than 100 is preferable.

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

[0129] The details of each component in Tables 3-5 are as follows. • NR: Natural rubber, TSR20 • Conjugated diene rubber 1-4: Conjugated diene rubber 1-4 synthesized as described above. • Comparative conjugated diene rubber: Comparative conjugated diene rubber synthesized as described above. • Nipol 1502: Styrene-butadiene rubber (manufactured by Nippon Zeon Co., Ltd.) (Does not contain specific modifying groups and therefore does not fall under the category of specific conjugated diene rubbers mentioned above) • BR: Nipol BR1220 manufactured by Nippon Zeon Co., Ltd. (butadiene rubber, Tg: -106℃) (Does not contain specific modifying groups and therefore does not fall under the category of specific conjugated diene rubbers mentioned above) • Carbon black: Tokai Carbon Co., Ltd. Seast 3 (HAF carbon black, nitrogen adsorption specific surface area (N2SA): 79m²) 2 / g) ·Silica: Solvay ZEOSIL 1165MP (CTAB adsorption specific surface area: 160m 2 / g) • Terpene resin: YS Resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (aromatic modified terpene resin, softening point: 125℃) • C5 / C9 resin: Manufactured by ENEOS Corporation, product name RD104 • C5 series resin: Manufactured by ENEOS Corporation, product name RA100 ·DCPD / C9 resin: Manufactured by Shanghai Yida Chemical Co., Ltd., product name RT-1102D • Comparative silane coupling agent: Evonik Si69 (not a specified silane coupling agent) • Silane coupling agent 1: 3-octanoylthio-1-propyltriethoxysilane (see compound below) (corresponds to a specific silane coupling agent)

[0130] [ka] • Silane coupling agent 2: Polysiloxane synthesized as described above (corresponds to a specific silane coupling agent) • Oil: Showa Shell Sekiyu Extract No. 4 S • Anti-aging agent: Nocrack 6C (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) • Wax: Sunnock (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) • Sulfur: Micron OT-20 manufactured by Shikoku Chemicals Co., Ltd. • Vulcanization accelerator: Sancellar CM-G (sulfenamide type) manufactured by Sanshin Chemical Industry Co., Ltd.

[0131] As can be seen from Tables 3 to 5, Examples 1 to 11, which contained a specific amount of specific conjugated diene rubber, silica, and a specific silane coupling agent, all showed excellent rolling performance, wet performance, processability, abrasion resistance, and chipping resistance. A comparison between Example 1 and Example 2 (a comparison of embodiments where only the type of specific conjugated diene rubber differed) showed that Example 1, in which the St+Vn of the specific conjugated diene rubber was 40 or less, exhibited superior rolling performance and wear resistance. Furthermore, a comparison between Example 1 and Example 2 (a comparison of embodiments where only the type of specific conjugated diene rubber differed) showed that Example 2, in which the St+Vn of the specific conjugated diene rubber was 35 or more, exhibited superior wet performance and chipping resistance. Furthermore, a comparison between Example 2 and Example 3 (a comparison of embodiments with different proportions of specific conjugated diene rubber in the rubber component) showed that Example 2, in which the proportion of specific conjugated diene rubber in the rubber component was 50% by mass or more, exhibited superior rolling performance, wet performance, abrasion resistance, and chipping resistance. Furthermore, a comparison between Example 1 and Examples 4-10 (a comparison of embodiments that differ only in the presence or absence of thermoplastic resin) showed that Examples 4-10, which contain thermoplastic resin, exhibited superior abrasion resistance. Furthermore, a comparison of Examples 4-7 (comparison of embodiments differing only in thermoplastic resin content) showed that Examples 5-7, in which the thermoplastic resin content was 10 parts by mass or more per 100 parts by mass of rubber component, exhibited superior wet performance, abrasion resistance, and chipping resistance. Among these, Examples 6-7, in which the above content was 30 parts by mass or more, showed even superior wet performance. Among these, Example 6, in which the above content was 45 parts by mass or less, showed even superior rolling performance, abrasion resistance, and chipping resistance. Furthermore, a comparison between Example 5 and Examples 8-10 (comparison of embodiments where the amount of thermoplastic resin is 20 parts by mass) showed that Examples 5 and 8, in which the thermoplastic resin contained a terpene-based resin, exhibited superior wet performance. In particular, Example 8, in which the thermoplastic resin contained at least two selected from the group consisting of terpene-based 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, exhibited even superior wet performance. Furthermore, a comparison between Example 1 and Example 11 (a comparison of embodiments that differ only in the type of specific silane coupling agent) showed that Example 1, in which the specific silane coupling agent is 3-octanoylthio-1-propyltriethoxysilane, exhibited superior wet performance.

[0132] On the other hand, the standard example which does not contain specific conjugated diene rubber and specific silane coupling agent, Comparative Example 1 which contains specific conjugated diene rubber but does not contain specific silane coupling agent, Comparative Example 2 which contains specific silane coupling agent but does not contain specific conjugated diene rubber, and Comparative Examples 3 to 5 which contain specific conjugated diene rubber and specific silane coupling agent but in which the proportion of specific conjugated diene rubber in the rubber component is less than 25% by mass, all had insufficient rolling performance, wet performance, processability, abrasion resistance, and chipping resistance. [Explanation of Symbols]

[0133] 1. Bead section 2 Sidewall section 3. Tire tread section 4. Carcass layer 5 Bead core 6. Bead Filler 7 Belt layer 8 Rim Cushion

Claims

1. It contains a rubber component (A) including a modified conjugated diene rubber (A1), silica (B), and a silane coupling agent (C). The modified conjugated diene rubber (A1) is a conjugated diene rubber that satisfies the following formulas (1) to (3) and has a modifying group containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent to the silicon atom, The proportion of the modified conjugated diene rubber (A1) in the rubber component (A) is 25% by mass or more. A tire rubber composition wherein the silane coupling agent (C) is 3-octanoylthio-1-propyltriethoxysilane or a polysiloxane represented by the average composition formula of the following formula (C2). [Vw １０％ ≦3.1×10 －６ ×Mw １０％ -2.77 (1) St+Vn≦50 (2) [Vw １０％ <4.7 (3) Mw in equations (1) and (3) １０％ and IVw １０％ The details are as follows: Gel permeation chromatography was performed on modified conjugated diene rubbers using a differential refractive index detector and a viscosity detector, with toluene containing 5 mmol / L of triethylamine as the eluent, at a temperature of 40°C. The weight-average molecular weight (Mw) is determined using the high molecular weight portion of the chromatogram peaks obtained by a differential refractive index detector, which accounts for 10% of the total peak area. １０％ Furthermore, the weight-average intrinsic viscosity IVw is determined using the high molecular weight portion of the chromatogram peaks obtained by the viscosity detector, which accounts for 10% of the total peak area. １０％ Let's assume that the unit of weight-average intrinsic viscosity is dL / g. In formula (2), St represents the proportion (mass%) of repeating units derived from styrene to the entire modified conjugated diene rubber, and Vn represents the proportion (mass%) of repeating units of 1,2-vinyl structure derived from conjugated diene to the entire modified conjugated diene rubber. (A) ａ (B) ｂ (C) ｃ (D) ｄ (R １ ) ｅ SiO （４－２ａ－ｂ－ｃ－ｄ－ｅ）／２ (C2) In formula (C2), 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. a to e satisfy the following relationships: 0 ≤ a < 1, 0 < b < 1, 0 < c < 3, 0 < d < 1, 0 ≤ e < 2, 0 < 2a + b + c + d + e < 4.

2. The modified conjugated diene rubber (A1) is Having a star-shaped structure with three or more branches, and having at least one branched chain of the star-shaped structure having a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, The tire rubber composition according to claim 1, wherein the aforementioned portion has a further main chain branching structure.

3. The tire rubber composition according to claim 1, wherein the content of the reinforcing filler containing the silica (B) is 50 parts by mass or more per 100 parts by mass of the rubber component (A).

4. Furthermore, the tire rubber composition according to claim 1 further contains a thermoplastic resin (D).

5. The thermoplastic resin (D) includes 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. The tire rubber composition according to claim 4, wherein the content of the thermoplastic resin (D) is 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component (A).

6. The thermoplastic resin (D) comprises at least two 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. The tire rubber composition according to claim 4, wherein the total content of the thermoplastic resin (D) is 50 parts by mass or less per 100 parts by mass of the rubber component (A).

7. A tire manufactured using the tire rubber composition described in any one of claims 1 to 6.

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