Rubber composition for tires and tires

Abstract

The present invention aims to provide a rubber composition for tires which shows excellent performance on ice, snow and wet surfaces and has excellent green strength, and a tire manufactured using the rubber composition for tires. The present invention is a rubber composition for tires which contains a diene rubber including a modified conjugated diene rubber, silica and a plasticizer, the modified conjugated diene rubber is a conjugated diene rubber which satisfies a specific formula and has a modifying group which contains a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto, the proportion of the modified conjugated diene rubber in the diene rubber is more than 15% by mass and not more than 50% by mass, the content of silica relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 90 parts by mass or less, and the content of the plasticizer relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 80 parts by mass or less.

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, rubber compositions for tires containing silica from the viewpoint of improving performance have been known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-29474 A Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, from the standpoint of safety and the like, there has been a demand for further improvements in tire performance on ice (ICE braking), performance on snow (Snow braking), wet performance, and green strength of rubber compositions before vulcanization. In this situation, 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 are desired in terms of performance on ice, performance on snow, and wet performance when made into tires, as well as the above-mentioned green strength.

[0005] In view of the above-mentioned circumstances, the present invention aims to provide a rubber composition for tires which, when made into a tire, exhibits excellent performance on ice, on snow and in wet conditions, and also has excellent green strength, and a tire manufactured using the rubber composition for tires. [Means for solving the problem]

[0006] As a result of intensive research aimed at solving the above problems, the inventors have found that the above problems can be solved by using a specific modified conjugated diene rubber as the rubber component and optimizing the contents of silica and plasticizer, etc., and have arrived at the present invention. That is, the present inventors have found that the above problems can be solved by the following configuration.

[0007] [1] The composition contains a diene rubber including a modified conjugated diene rubber (A1), silica (B), and a plasticizer (C), The modified conjugated diene rubber (A1) satisfies the following formula (1) and the following formula (2) and has a modifying group containing 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 is more than 15 mass% and 50 mass% or less; the content of the silica (B) relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 90 parts by mass or less, The rubber composition for tires, wherein the content of the plasticizer (C) per 100 parts by mass of the diene rubber is 30 parts by mass or more and 80 parts by mass or less. 4.7≦IVw 10% ≦3.1×10 -6 ×Mw 10% -2.77 (1) St+Vn≦50 (2) Mw in formula (1) 10% and IVw 10% The details are as follows: The modified conjugated diene rubber is subjected to gel permeation chromatography measurement using a differential refractive index detector and a viscosity detector. The weight average molecular weight calculated using the high molecular weight side portion of the peak obtained by the differential refractive index detector, which is 10% of the total peak area, is defined as Mw 10% The weight-average intrinsic viscosity determined by using the high molecular weight portion of the peak in the chromatogram obtained by the viscometer, which is 10% of the total peak area, is defined as IVw 10% However, the unit of weight average intrinsic viscosity is dL / g. In formula (2), St represents the ratio (mass%) of repeating units derived from styrene to the entire modified conjugated diene rubber, and Vn represents the ratio (mass%) of repeating units of 1,2-vinyl structure derived from conjugated diene to the entire modified conjugated diene rubber. [2] The modified conjugated diene rubber (A1) is a star structure having three or more branches, at least one branch of which has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group; The rubber composition for a tire according to [1], wherein the portion further has a main chain branched structure. [3] The rubber composition for a tire according to [1] or [2], wherein the plasticizer (C) contains at least one selected from the group consisting of oils, liquid polymers, and thermoplastic resins. [4] The rubber composition for tires according to any one of [1] to [3], wherein the plasticizer (C) contains at least one selected from the group consisting of liquid polymers and vegetable oils, in an amount of 1 part by mass or more per 100 parts by mass of the diene rubber. [5] The rubber composition for a tire according to any one of [1] to [4], wherein the diene rubber further contains SBR and / or a mixture of BR and a liquid polymer. [6] The rubber composition for a tire according to [5], wherein the liquid polymer contained in the mixture includes a modified liquid polymer. [7] The rubber composition for a tire according to any one of [1] to [6], further comprising an epichlorohydrin rubber, the content of the epichlorohydrin rubber being 1 part by mass or more and 25 parts by mass or less per 100 parts by mass of the diene rubber. [8] The rubber composition for tires according to any one of [1] to [7], wherein the plasticizer (C) contains a thermoplastic resin, and the content of the thermoplastic resin is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the diene rubber. [9] A tire manufactured using the rubber composition for a tire according to any one of [1] to [8]. Effect of the Invention

[0008] As described below, according to the present invention, it is possible to provide a rubber composition for tires which, when made into a tire, exhibits excellent performance on ice, on snow and on wet surfaces, and also has excellent green strength, and a tire manufactured using the rubber composition for tires. [Brief description of the drawings]

[0009] [Figure 1] This is an example of a GPC chromatogram. [Diagram 2] 1 is a partial cross-sectional schematic view showing an example of an embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The rubber composition for tires and the like 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. In addition, 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 the components refers to the total content unless otherwise specified. In addition, the method for producing each component is not particularly limited unless otherwise specified, and may be, for example, a conventionally known method. In addition, with regard to a rubber composition for tires, the ice performance, snow performance, and wet performance when made into a tire, and the green strength of the rubber composition before vulcanization are also simply referred to as "ice performance," "snow performance," "wet performance," and "green strength," respectively. In addition, in this specification, a power of 10 may be represented as E. For example, E+5 represents 10 to the fifth power. In this specification, silica (B) may be simply referred to as silica. The same applies to plasticizers (C) and the like. 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 "based on 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 amount of the 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") has The composition contains a diene rubber including a modified conjugated diene rubber (A1), silica (B), and a plasticizer (C), The modified conjugated diene rubber (A1) satisfies the formula (1) described later and the formula (2) described later, and has a modifying group containing 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 is more than 15 mass% and 50 mass% or less; the content of the silica (B) relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 90 parts by mass or less, In the rubber composition for tires, the content of the plasticizer (C) is 30 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the diene rubber.

[0012] It is believed that the composition of the present invention, having such a structure, can solve the above-mentioned problems. Although the reason for this is not clear, it is believed to be roughly as follows. Generally, a rubber composition containing a large amount of plasticizer has low sheet strength and therefore requires green strength. On the other hand, the composition of the present invention contains a modified conjugated diene rubber (A1) as a rubber component. The modified conjugated diene rubber (A1) is a conjugated diene rubber that satisfies the formula (1) and the formula (2) described below 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 (hereinafter, the modified conjugated diene rubber (A1) is also referred to as a "specific conjugated diene rubber"). 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. From the studies of the present inventors, it is believed that the high weight average molecular weight and weight average intrinsic viscosity of rubber satisfying equation (1) leads to improved green strength. In addition, the inventors of the present invention have found that the specific modifying group of the specific conjugated diene rubber interacts with silica. Therefore, the dispersibility of silica in the composition of the present invention is extremely high, which leads to excellent effects (performance on ice, performance on snow, wet performance) even if the composition of the present invention contains a plasticizer (C) within a certain range.

[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, as a rubber component, a diene rubber including a specific conjugated diene rubber. The composition of the present invention may further contain, as the rubber component, a diene rubber other than the specific conjugated diene rubber, and / or a rubber component other than the diene rubber (non-diene rubber). In the present invention, a preferred embodiment of the rubber component is a solid rubber at 25°C.

[0015] [Specific conjugated diene rubber] The specific conjugated diene rubber is a conjugated diene rubber that satisfies the formula (1) described below and the formula (2) described below 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 (other monomer) that becomes such a repeating unit include vinyl monomers, alkenes (e.g., ethylene, propylene, butene), etc. Examples of the vinyl monomer include aromatic vinyl (e.g., styrene), acrylonitrile, and the specific branching agent described later.

[0019] <Example> 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), chloroprene rubber (CR), etc. Examples of the aromatic vinyl-conjugated diene copolymer rubber include styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, etc. The skeleton of the specific conjugated diene rubber is preferably SBR, since 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 any one of the terminals, main chain, or side chain of the skeleton of the specific conjugated diene rubber. The specific modifying group preferably contains a silicon atom and an oxygen atom adjacent thereto as an alkoxysilyl group, because the effect of the present invention is more excellent. The alkoxysilyl group is represented by the formula -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 this provides better effects of the present invention. 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)] The specific conjugated diene rubber satisfies the following formula (1). Formula (1) specifies 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 that have a small molecular size relative to their molecular weight, such as those that have branches, tend to satisfy formula (1). The reason for limiting the molecular weight side is that it has a large effect on the physical properties of the entire polymer.

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

[0023] Mw in formula (1) 10% and IVw 10% is calculated as follows: The modified conjugated diene rubber is subjected to gel permeation chromatography measurement using a differential refractive index detector (RI detector) and a viscosity detector. The weight average molecular weight calculated using the high molecular weight side portion of the chromatogram peak obtained by the differential refractive index detector, which is 10% of the total peak area, is defined as Mw 10% The weight-average intrinsic viscosity determined by using the high molecular weight portion of the peak in the chromatogram obtained by the viscometer, which is 10% of the total peak area, is defined as IVw 10%However, the unit of weight average intrinsic viscosity is dL / g.

[0024] Hereinafter, Mw in formula (1) 10% and IVw 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 is used as the eluent. Three columns packed with polystyrene gel (product names "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation) are connected together and used. The sample to be measured is dissolved in toluene to a concentration of 1 mg / mL to prepare a measurement solution, and 100 μL of the measurement solution is injected into the GPC measurement device and measured under conditions of an oven temperature of 40°C and a toluene flow rate of 1 mL / min.

[0027] The weight average molecular weight is calculated using the high molecular weight side (the side with a short elution time) which is 10% of the total area of ​​the peaks (peaks due to modified conjugated diene rubber) in the chromatogram (horizontal axis: elution time, vertical axis: signal intensity) obtained by the differential refractive index detector. The weight average molecular weight obtained is Mw 10% Let us assume that.

[0028] In addition, the weight-average intrinsic viscosity is calculated using the high molecular weight side (the side with the short elution time) which is 10% of the total area of ​​the peaks (peaks derived from 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 obtained is called IVw 10% Let us assume that. 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. The Mw 10% and IVw 10% Request.

[0030] As a method for making the modified conjugated diene rubber satisfy the formula (1), for example, 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 later can be mentioned.

[0031] Mw 10% In order to obtain better effects of the present invention, the molecular weight is preferably 100,000 to 10,000,000, and more preferably 1,000,000 to 5,000,000. Mw 10% For the reason that the effects of the present invention (particularly, green strength) are more excellent, the molecular weight is preferably more than 28,000,000 and not more than 10,000,000, and more preferably from 3,000,000 to 5,000,000.

[0032] IVw 10% is preferably from 4.7 to 8, and more preferably from 4.7 to 6, because the effects of the present invention are more excellent. IVw 10% is preferably more than 5.5 and 8 or less because the effects of the present invention (particularly, green strength) are better.

[0033] [Formula (2)] The specific conjugated diene rubber satisfies the following formula (2).

[0034] St+Vn≦50 (2)

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

[0036] St+Vn is preferably from 10 to 45, and more preferably from 25 to 45, because the effects of the present invention are more excellent.

[0037] St is preferably from 5 to 40, more preferably from 10 to 35, and even more preferably from 15 to 30, because the effects of the present invention are more excellent.

[0038] Vn is preferably from 5 to 30, and more preferably from 10 to 20, 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 from 100,000 to 2,000,000, and more preferably from 200,000 to 1,300,000, because the effects of the present invention are more excellent. The weight average molecular weight (Mw) of the specific conjugated diene rubber is measured by the same method as 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 from -100°C to -30°C, and more preferably from -80°C to -45°C, for reasons of better effect 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 embodiment 1] 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 having a specific modifying group as a branch point, and further preferably is a conjugated diene rubber represented by the following formula (A), because the effects of the present invention are more excellent.

[0042] [ka]

[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 this provides a better effect of the present invention. X preferably contains a nitrogen atom as an amino group because the effect of the present invention is more excellent.

[0045] As described above, P represents a conjugated diene polymer chain. A plurality of P's 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 more. There is no particular upper limit to n, but it is preferably 30 or less because the effects of the present invention are more excellent.

[0047] [Preferred embodiment 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 portion derived from a specific branching agent described later, and further has a main chain branched structure, because the effects of the present invention are more excellent. The main chain branched structure refers to a structure in which a branched chain (conjugated diene polymer chain) forms a branch point at a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and a polymer chain (e.g., another conjugated diene polymer chain) 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 more than 15 mass % and 50 mass % or less. The above ratio is preferably from 20% by mass to 50% by mass, and more preferably from 25% by mass to 40% by mass, because the effects of the present invention are superior.

[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 diene rubbers other than the specific conjugated diene rubber in the diene rubber (other diene rubbers) that the composition of the present invention may further contain include natural rubber (NR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber (e.g., styrene-butadiene rubber (SBR), styrene-isoprene copolymer rubber, etc.), isoprene rubber (IR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR), etc. From the viewpoint of obtaining superior effects of the present invention, the other diene-based rubber that the rubber component can further contain preferably contains natural rubber (NR) and / or butadiene rubber (BR), and more preferably contains natural rubber (NR) and butadiene rubber (BR). The proportion of the other diene rubber can be the remainder obtained by subtracting the range of the proportion of the specific conjugated diene rubber from 100% by mass.

[0051] (Non-diene rubber) When the rubber component further contains a rubber component other than the diene rubber (non-diene rubber) as the other rubber component, an example of the non-diene rubber is epichlorohydrin rubber.

[0052] (epichlorohydrin rubber) When the rubber component further contains a non-diene rubber, from the viewpoint of obtaining better effects of the present invention, the non-diene rubber preferably contains an epichlorohydrin rubber.

[0053] When the rubber component further contains epichlorohydrin rubber, the epichlorohydrin rubber is incompatible with diene rubber and therefore forms domains in the cured product after vulcanization, increasing surface roughness and providing appropriate flexibility, thereby further improving performance on ice. In addition, the chlorine contained in the epichlorohydrin rubber interacts with silica due to its high polarity, thereby maintaining or further improving wet performance.

[0054] Examples of epichlorohydrin rubbers include one or more of epichlorohydrin homopolymers, epichlorohydrin-ethylene oxide copolymers, epichlorohydrin-propylene oxide copolymers, epichlorohydrin-allyl glycidyl ether copolymers, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymers, epichlorohydrin-propylene oxide-allyl glycidyl ether copolymers, and epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether copolymers.

[0055] When the rubber component further contains an epichlorohydrin rubber, from the viewpoint of achieving better effects of the present invention (particularly performance on ice), the epichlorohydrin rubber preferably contains a copolymer of epichlorohydrin and ethylene oxide.

[0056] When the rubber component further contains an epichlorohydrin rubber, from the viewpoints of achieving better effects of the present invention and excellent abrasion resistance, the epichlorohydrin rubber preferably has a Mooney viscosity at 100° C. of 65 to 100. The Mooney viscosity at 100° C. can be measured in accordance with JIS K6300-1:2013.

[0057] When the rubber component further contains an epichlorohydrin rubber, the content of the epichlorohydrin rubber is preferably 1 part by mass or more and 25 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the diene rubber, from the viewpoint of obtaining better effects of the present invention.

[0058] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) of rubber components other than the specific conjugated diene rubber, and liquid polymers described later, may be standard polystyrene-equivalent values ​​obtained by gel permeation chromatography (GPC) measurement under the following conditions. Solvent: Tetrahydrofuran Detector: RI detector

[0059] [Method of manufacturing specific conjugated diene rubber] The method for producing the specific conjugated diene rubber is not particularly limited, but a method including 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 in which a monomer containing a conjugated diene is polymerized by anionic polymerization to obtain a conjugated diene-based polymer. (2) A modification step in which the 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 a "specific modifier") to obtain a conjugated diene rubber having a specific modifying group.

[0060] [Polymerization process] The polymerization step is a step of obtaining a conjugated diene-based polymer by polymerizing a monomer containing a conjugated diene by anionic polymerization.

[0061] <Anionic polymerization> The anionic polymerization is not particularly limited, but anionic polymerization using an organolithium compound as an initiator is preferred because the effects of the present invention are more excellent.

[0062] The organolithium compound is not particularly limited, and specific examples thereof include mono-organolithium compounds such as n-butyl lithium (n-BuLi), sec-butyl lithium, tert-butyl lithium, n-propyl lithium, iso-propyl lithium, and benzyl lithium; and polyfunctional organolithium compounds such as 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithiobenzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-trilithio-2,4,6-triethylbenzene. Among these, the mono-organolithium compounds of n-butyl lithium, sec-butyl lithium, and tert-butyl lithium are preferred, and n-butyl lithium is more preferred, because the effects of the present invention are more excellent.

[0063] 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 better effects of the present invention.

[0064] <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.

[0065] (Specific branching agent) The monomer preferably contains a vinyl monomer containing an alkoxysilyl group or a halosilyl group (hereinafter also referred to as a "specific branching agent") because the effect of the present invention is 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, for reasons that the effects of the present invention are more excellent.

[0066] (1) Specific examples Specific examples of aromatic vinyls containing an alkoxysilyl group include 1-(trimethoxysilyl)-4-vinylbenzene and 1,1-bis(4-trimethoxysilylphenyl)ethylene. Examples of aromatic vinyls containing a halosilyl group include trichloro(4-vinylphenyl)silane and 1,1-bis(4-trichlorosilylphenyl)ethylene.

[0067] (2) Usage amount The amount of the specific branching agent used is preferably 0.001 to 0.1% by mass, and more preferably 0.005 to 0.05% by mass, based on the conjugated diene, because this provides better effects for the present invention.

[0068] <Polar compounds> In the polymerization step, a polar compound may be added. This allows the monomers to be randomly copolymerized. In addition, polar compounds tend to be usable as vinylating agents for controlling the microstructure of conjugated dienes. In addition, polar compounds tend to be effective in promoting polymerization reactions.

[0069] 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.

[0070] (Amount used) The amount of the polar compound used is preferably 0.01 mol or more and 100 mol or less per mol of the initiator, because the effect of the present invention is more excellent.

[0071] [Modification step] The modification process is a process in which the conjugated diene polymer obtained in the polymerization process is reacted 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.

[0072] In the modification step, it is considered that the active terminal of the conjugated diene polymer obtained in the polymerization step is bonded to the silicon atom of the specific modifier. For example, when the specific modifier contains an alkoxysilyl group, it is considered that the active terminal is bonded to the silicon atom of the alkoxysilyl group, and the alkoxy group is eliminated. In addition, when the conjugated diene polymer obtained in the polymerization step has a portion derived from a specific branching agent, in addition to the above-mentioned active terminal, the alkoxysilyl group or halosilyl group of the above-mentioned portion is also considered to react with the specific modifying agent (e.g., alkoxysilyl group). In addition, the alkoxysilyl group or halosilyl group of the above-mentioned portion is also considered to react with the active terminal of another conjugated diene polymer. As a result, the conjugated diene polymer having a portion derived from a specific branching agent has a main chain branched structure (another conjugated diene polymer chain) in the above-mentioned portion.

[0073] <Specific modifier> The specific modifier is a compound containing a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto. For the reason that the effect of the present invention is more excellent, the specific modifier preferably contains a silicon atom and an 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 a Si-N bond). The specific modifying agent 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) because this provides a better effect of the present invention. The specific modifying agent preferably has two or more (preferably three or more) sites capable of reacting with an active terminal such as an alkoxysilyl group. When the specific modifying agent has a plurality of such sites, the specific modifying agent functions as a coupling agent that connects conjugated diene polymers together.

[0074] (Specific examples) Specific examples of the specific modifier 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 -(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 are examples of tertiary amines having an alkoxysilyl group and a group containing a cyclic silazane structure.

[0075] (Amount used) The amount of the specific modifying agent used is preferably 0.01 to 1% by mass, and more preferably 0.02 to 0.2% by mass, based on the conjugated diene, because this provides better effects for the present invention.

[0076] [Other steps] The production method of the present invention may include steps (other steps) other than the steps described above. Other steps include a polymerization terminating step in which a polymerization terminator (eg, methanol) is added, and a solvent removal step in which the solvent is removed by steam stripping.

[0077] [Average Tg] The glass transition temperature (hereinafter also referred to as "average Tg") of the entire rubber component is not particularly limited, but in order to obtain better effects of the present invention, it is preferably higher than -90°C and -45°C or lower, and more preferably -85°C or higher and -50°C or lower. The average Tg of the rubber components is the sum (weighted average value of glass transition temperatures) of the glass transition temperatures (Tg) of each rubber component multiplied by the mass fraction of each rubber component.

[0078] [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.

[0079] [2] Silica The composition of the present invention contains silica [silica (B)]. 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. Silica derived from biomass such as rice husk may also be used. The above silica may be used alone or in combination of two or more kinds.

[0080] [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. However, in order to obtain a superior effect of the present invention, it is preferable to use a surface area of ​​100 to 300 m. 2 / g, and 150 to 200m 2 It is more preferable that the molecular weight is / g. Here, the CTAB adsorption specific surface area is a value measured in accordance with JIS K6430:2008, Annex G.

[0081] [Content] In the composition of the present invention, the content of silica is 30 parts by mass or more and 90 parts by mass or less based on 100 parts by mass of the diene rubber. The content of silica is preferably 50 parts by mass or more and less than 80 parts by mass, and more preferably 60 parts by mass or more and 75 parts by mass or less, per 100 parts by mass of the above-mentioned diene-based rubber, because the effects of the present invention are more excellent.

[0082] [3] Plasticizers The composition of the present invention contains a plasticizer [plasticizer (C)]. In the present invention, the plasticizer is not particularly limited as long as it is a compound that can plasticize or soften the rubber component. In the present invention, the plasticizer does not fall under the above-mentioned rubber component.

[0083] The plasticizer includes softeners, lubricants, and extender oils that can be used for the purpose of plasticizing rubber, which can be added to general rubber compositions, but does not include wax. In a preferred embodiment, the plasticizer is liquid at 25°C, or if it is solid at 25°C, has a softening point of 160°C or lower.

[0084] The plasticizer preferably contains at least one selected from the group consisting of oil, liquid polymer, and thermoplastic resin, because the effects of the present invention are more excellent.

[0085] In addition, the plasticizer preferably contains at least one selected from the group consisting of liquid polymers and vegetable oils, because this provides better effects of the present invention (particularly performance on ice, performance on snow, etc.).

[0086] The plasticizer preferably contains a thermoplastic resin because the effects of the present invention (particularly, wet performance and green performance) are more excellent.

[0087] 〔oil〕 Examples of oils include aromatic oils, naphthenic oils, paraffinic oils, and vegetable oils. The oil preferably contains an aromatic oil and / or a vegetable oil, because the effect of the present invention is more excellent. The aromatic oil is not particularly limited as long as it is an aromatic oil that can be generally used in rubber compositions. The vegetable oil is not particularly limited as long as it is an oil derived from a plant. For both, examples include conventionally known aromatic oils and vegetable oils.

[0088] [Liquid Polymer] Examples of liquid polymers include liquid butyl rubber, liquid isoprene rubber, liquid butadiene rubber, and liquid styrene-butadiene rubber. The liquid polymer may be a modified liquid polymer (modified liquid polymer), and examples of the modified liquid polymer include epoxy-modified liquid polymers, carboxy-modified liquid polymers, amine-modified liquid polymers, alkoxysilyl-modified liquid polymers, hydroxyl-modified liquid polymers, siloxane-modified liquid polymers, and mercapto-modified liquid polymers. When the liquid polymer is a modified liquid polymer, examples of the modifying group possessed by the modified liquid polymer include an epoxy group, a carboxy group, an amino group (-NH2), an imino group (-NH-), an alkoxysilyl group, a trialkylsilyl group, a hydroxyl group, a polysiloxane group, a mercapto group, and combinations thereof.

[0089] The liquid polymer preferably contains an alkoxysilyl-modified liquid polymer because the effect of the present invention is more excellent. The alkoxysilyl-modified liquid polymer is a liquid polymer having an alkoxysilyl group. Examples of the alkoxy group in the alkoxysilyl group include a methoxy group and an ethoxy group. The alkoxysilyl group in the alkoxysilyl-modified liquid polymer can be bonded to the main chain of the alkoxysilyl-modified liquid polymer directly or via a divalent linking group. The divalent linking group is not particularly limited. The alkoxysilyl group contained in the alkoxysilyl-modified liquid polymer may be any one of a trialkoxysilyl group, a dialkoxysilyl group, and a monoalkoxysilyl group. When the alkoxysilyl group is a dialkoxysilyl group or a monoalkoxysilyl group, the dialkoxysilyl group or the like can further have a modifying group represented by the formula: *-RX. X in the above-mentioned modifying group represents a functional group such as an amino group, a mercapto group, an epoxy group, a carboxy group, a hydroxyl group, or an N-trialkylsilyl-imino group. X is preferably an amino group or an N-trialkylsilyl-imino group because the effect of the present invention is more excellent. The alkyl group bonded to the silicon atom of the N-trialkylsilyl-imino group is not particularly limited. For example, an alkyl group having 1 to 10 carbon atoms such as a methyl group or an ethyl group can be mentioned. In the above modifying group, R represents a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include alkylene groups having 1 to 6 carbon atoms. The "*" in the above modified group indicates a bonding position. The modified group represented by the above formula can be bonded to the silicon atom in the dialkoxysilyl group or the like directly or via a divalent linking group. The divalent linking group is not particularly limited. For reasons why the effects of the present invention are more excellent, the liquid polymer preferably contains a dialkoxysilyl-modified liquid polymer having a modifying group represented by the formula: *-RX, more preferably contains a dialkoxysilyl-modified liquid polymer having a modifying group represented by the formula: *-R-NH2 or *-R-NH-Si(alkyl)3, and even more preferably contains a dialkoxysilyl-modified liquid butadiene rubber having a modifying group represented by the formula: *-R-NH2 or *-R-NH-Si(alkyl)3.

[0090] The liquid polymer preferably contains a liquid butadiene rubber because the effect of the present invention is more excellent. The liquid butadiene rubber may be either an unmodified liquid butadiene rubber or a modified liquid butadiene rubber, or may contain both.

[0091] The weight average molecular weight (Mw) of the liquid polymer is preferably 3,000 or more and less than 100,000, and more preferably 5,000 or more and less than 80,000, because the effects of the present invention are more excellent.

[0092] [Thermoplastic resin] Examples of the thermoplastic resin include coumarone resins (e.g., coumarone resin, coumarone-indene resin, coumarone-indene-styrene resin), phenol resins (e.g., phenol 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), terpene resins (e.g., terpene resin, modified rosin), and the like. 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.

[0093] 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, because this provides better effects for the present invention.

[0094] For the reason that the effects of the present invention are more excellent, the softening point of the thermoplastic resin is preferably 60 to 160° C. The softening point can be measured in accordance with JIS K6220-1:2015.

[0095] [Preferred embodiment 3] In one preferred embodiment, the diene rubber as the rubber component further contains a mixture of SBR (styrene butadiene rubber) and / or BR (butadiene rubber) with a liquid polymer, because this provides a better effect of the present invention. That is, when the diene rubber as the rubber component further contains SBR and / or BR, and the plasticizer contains a liquid polymer, it is preferable that the diene rubber as the rubber component contains a mixture in which at least a part or all of the SBR and / or at least a part or all of the BR and at least a part or all of the liquid polymer are premixed, It is more preferable that the composition contains a mixture obtained by premixing all of the BR with at least a part or all of the liquid polymer. The mixture may be in either a solid or liquid state at 25°C. The method for obtaining the mixture is not particularly limited, and may be, for example, a conventionally known mixing method.

[0096] In the above-mentioned preferred embodiment 3, the liquid polymer contained in the above-mentioned mixture preferably contains a modified liquid polymer (modified liquid polymer) because the effect of the present invention is more excellent. The modified liquid polymer is the same as described above.

[0097] In order to obtain a more excellent effect of the present invention, the plasticizer preferably contains at least one oil selected from the group consisting of aromatic oils, naphthenic oils, and paraffin oils, and at least one oil selected from the group consisting of vegetable oils, liquid polymers, and thermoplastic resins. More preferably, the plasticizer comprises an aromatic oil, a vegetable oil, a liquid polymer, and a thermoplastic resin; It is more preferable that the plasticizer contains an aromatic oil, a vegetable oil, a modified liquid polymer, and a thermoplastic resin, and that the modified liquid polymer is a mixture with SBR and / or BR as the rubber component.

[0098] [Content] In the present invention, the content of the plasticizer relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 80 parts by mass or less. The content of the plasticizer is preferably 40 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of the diene rubber, because the effects of the present invention are more excellent.

[0099] When the plasticizer contains at least one oil selected from the group consisting of aromatic oil, naphthenic oil, and paraffin oil, the content of the at least one oil selected from the group consisting of aromatic oil, naphthenic oil, and paraffin oil (the total content when there are two or more oils; the same applies below) is preferably 30 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 60 parts by mass or less, per 100 parts by mass of diene rubber, for reasons of superior effects of the present invention.

[0100] When the plasticizer contains at least one selected from the group consisting of liquid polymers and vegetable oils, the content of the at least one selected from the group consisting of liquid polymers and vegetable oils is preferably 1 part by mass or more, and more preferably 5 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of diene rubber, because the effects of the present invention are more excellent.

[0101] When the plasticizer contains vegetable oil, the content of the vegetable oil is preferably 5 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of diene rubber, because the effects of the present invention are better.

[0102] When the plasticizer contains a liquid polymer, the content of the liquid polymer is preferably 5 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of diene-based rubber, because the effects of the present invention are better. When the plasticizer contains an unmodified liquid polymer, the content of the unmodified liquid polymer is preferably 5 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of diene rubber, because the effects of the present invention are better. When the plasticizer contains a modified liquid polymer (including the case where the modified liquid polymer is a mixture as described above), the content of the modified liquid polymer is preferably 5 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of diene rubber, because the effects of the present invention are better.

[0103] When the plasticizer contains a thermoplastic resin, the content of the thermoplastic resin is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the diene rubber, because the effects of the present invention are better.

[0104] [4] Optional component The composition of the present invention may contain components (optional components) other than the above-mentioned components, as necessary. Examples of such components include various additives commonly used in rubber compositions, such as fillers other than silica (preferably carbon black), thermally expandable microcapsules, silane coupling agents, stearic acid, zinc oxide (zinc white), antioxidants, waxes, processing aids, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), and vulcanization activators.

[0105] [Silane coupling agents] The composition of the present invention preferably further contains a silane coupling agent because the effects of the present invention are more excellent.

[0106] 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, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Among them, an alkoxy group is preferable because the effects of the present invention are more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms of 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 the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, and a propoxy group.

[0107] The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, and examples thereof include 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., an octanoylthio group), and the like. Among these, a sulfide group (particularly a disulfide group or a tetrasulfide group), a mercapto group, and a blocked mercapto group are preferred because they provide better effects of the present invention. The silane coupling agents may be used alone or in combination of two or more kinds.

[0108] The silane coupling agent is preferably a sulfur-containing silane coupling agent because the effects of the present invention are more excellent.

[0109] Specific examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, and the like. One of these may be used alone, or two or more may be used in combination.

[0110] [Content] In the composition of the present invention, the content of the silane coupling agent is not particularly limited, but it is preferably 2 to 20 parts by mass per 100 parts by mass of the diene rubber described above, because the effects of the present invention are more excellent.

[0111] In addition, in the composition of the present invention, the content of the silane coupling agent is preferably 1 to 20 mass %, and more preferably 5 to 15 mass %, relative to the above-mentioned silica content, because the effects of the present invention are more excellent.

[0112] [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 kinds. The carbon black 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.

[0113] [N2SA] The nitrogen adsorption specific surface area (N2SA) of the carbon black 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 It is more preferable that the molecular weight is / g. Here, the nitrogen adsorption specific surface area (N2SA) is the amount of nitrogen adsorbed on the surface of carbon black measured according to JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0114] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but because the effects of the present invention are more excellent, the content is preferably 1 to 100 parts by mass, and more preferably 2 to 30 parts by mass, per 100 parts by mass of the above-mentioned diene-based rubber.

[0115] [Vulcanization accelerator] The composition of the present invention preferably further contains a vulcanization accelerator because the effects of the present invention are more excellent. Examples of the vulcanization accelerator include sulfenamide-based, thiuram-based, and guanidine-based accelerators.

[0116] [Content] In the composition of the present invention, the content of the vulcanization accelerator is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 6 parts by mass, relative to 100 parts by mass of the above-mentioned diene rubber, because the effects of the present invention are more excellent.

[0117] [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 of kneading the above-mentioned components using a known method or device (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 the sulfur or the vulcanization accelerator. The composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0118] [II] Tires The tire of the present invention is a tire manufactured using the above-mentioned composition of the present invention. 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.

[0119] 2 is a schematic partial cross-sectional view of a tire showing one 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 FIG.

[0120] In FIG. 2, reference numeral 1 denotes a bead portion, reference numeral 2 denotes a sidewall portion, and reference numeral 3 denotes a tire tread portion. Between the pair of left and right bead portions 1, a carcass layer 4 having fiber cords embedded therein is installed, and the ends of this carcass layer 4 are folded back and wrapped around the bead cores 5 and bead fillers 6 from the inside to the outside of the tire. In the tire tread portion 3, a belt layer 7 is disposed on the outer side of the carcass layer 4 over one circumference of the tire. In addition, a rim cushion 8 is disposed in the bead portion 1 at a portion that comes into contact with the rim. At least one of the reference numerals 2 to 3, 5 to 6, and 8 (preferably reference numeral 3) is formed from the above-mentioned composition of the present invention.

[0121] The tire of the present invention can be manufactured, for example, according to a conventionally known method. The gas to be filled in the tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0122] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0123] [Synthesis of conjugated diene rubber] Each conjugated diene rubber was synthesized as follows.

[0124] [Conjugated diene rubber 4] <Polymerization process> In a stirred autoclave, cyclohexane 1000g / h (hour), tetramethylethylenediamine 0.023g / h, 1,3-butadiene 176.4g / h, 1-butene 0.406g / h, and styrene 23.6g / h were charged under a nitrogen atmosphere, and n-butyllithium was continuously added at 1.43mmol / h to initiate polymerization at 70°C. When the polymerization was sufficiently stabilized, 1-(trimethoxysilyl)-4-vinylbenzene (branching agent) was added at 0.02g / h and the mixture was stirred to react. The branching agent corresponds to the specific branching agent described above.

[0125] <Denaturation process> To the solution discharged from the reactor outlet, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine (modifier) ​​was added at 0.08 g / h, and the mixture was stirred to react.

[0126] Thereafter, methanol was added as a polymerization terminator to obtain a solution containing a conjugated diene rubber.

[0127] To the resulting solution, 1.14 parts by mass of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent per 100 parts by mass of the conjugated diene rubber, and the solvent was 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 4.

[0128] The conjugated diene rubber 4 is a reaction product between a conjugated diene polymer, which is a copolymer of butadiene, styrene and a branching agent, and a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto, which is derived from the modifier. The conjugated diene rubber 4 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 a branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0129] [Conjugated diene rubber 5] A solid conjugated diene rubber was obtained in the same manner as for conjugated diene rubber 4, except that the amount of each component was changed as shown in Table 1. The obtained conjugated diene rubber is also referred to as conjugated diene rubber 5.

[0130] The conjugated diene rubber 5 is a reaction product between a conjugated diene polymer, which is a copolymer of butadiene, styrene and a branching agent, and a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto, which is derived from the modifier. 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 a branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0131] [Conjugated diene rubber 2 (comparison)] A solid conjugated diene rubber was obtained in the same manner as for conjugated diene rubber 4, except that the amount of each component was changed as shown in Table 1. The obtained conjugated diene rubber is also referred to as conjugated diene rubber 2.

[0132] The conjugated diene rubber 2 is a reaction product between a conjugated diene polymer, which is a copolymer of butadiene, styrene and a branching agent, and a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto, which is derived from the modifier. 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 a branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0133] [Conjugated diene rubber 3 (comparison)] A solid conjugated diene rubber was obtained in the same manner as for conjugated diene rubber 4, except that the amount of each component was changed as shown in Table 1. The obtained conjugated diene rubber is also referred to as conjugated diene rubber 3.

[0134] The conjugated diene rubber 3 is a reaction product between a conjugated diene polymer, which is a copolymer of butadiene, styrene and a branching agent, and a modifier, and is a modified conjugated diene rubber having a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom and an oxygen atom adjacent thereto, which is derived from the modifier. 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 a branching agent, and the portion derived from the branching agent has a further main chain branched structure (conjugated diene polymer chain).

[0135] [Table 1]

[0136] [Weight average molecular weight, weight average intrinsic viscosity, styrene content, vinyl content, glass transition temperature] The conjugated diene rubbers synthesized as described above (conjugated diene rubbers 4 and 5, and conjugated diene rubbers (comparison) 2 and 3) were 10% , IVw, IVw 10% , St, Vn, and St+Vn are shown in Table 2. Table 2 also shows the results for NS612 (described later) used as conjugated diene rubber 1 (for comparison). In Table 2, the "right side" of formula (1) is the right side of formula (1), "3.1 × 10 -6 ×Mw 10% represents the value of "-2.77". The "left side" of equation (1) is "4.7". In Table 2, "Applicable" of formula (1) indicates whether formula (1) is applicable or not. Specifically, "A" is IVw 10% satisfies formula (1), and "B" is IVw 10% does not satisfy equation (1). In addition, in Table 2, "St+Vn" in formula (2) represents the above-mentioned St+Vn.

[0137] [Table 2]

[0138] As shown in Table 2, all of the conjugated diene rubbers 4 to 5 satisfy the formula (1) and the formula (2). As described above, all of the conjugated diene rubbers 4 to 5 are modified conjugated diene rubbers having a specific modifying group. Therefore, all of the conjugated diene rubbers 4 to 5 correspond to the above-mentioned specific conjugated diene rubber. As shown in Table 2, the conjugated diene rubbers 1 and 2 (comparison) satisfy the formula (2) but do not satisfy the formula (1), and therefore do not fall under the above-mentioned specific conjugated diene rubber. Conjugated diene rubber 3 (comparison) satisfies formula (1) but does not satisfy formula (2), and therefore does not fall under the category of the above-mentioned specific conjugated diene rubber. As described above, the conjugated diene rubbers 2 and 3 (comparison) are modified conjugated diene rubbers having a specific modifying group.

[0139] [Preparation of rubber composition for tires] The components in Tables 3 and 4 below were mixed in the compositions (parts by mass) shown in the tables. Specifically, first, the components other than sulfur and the vulcanization accelerator in Tables 3 and 4 were mixed in a 1.8 L internal mixer at 160°C or less for 5 minutes, and a master batch was discharged. Then, sulfur and the vulcanization accelerator were added to the master batch, and the mixture was mixed at 100°C or less using an open roll to produce each rubber composition for tires.

[0140] [Tire manufacturing] Each of the obtained rubber compositions for tires was used in the tread portion of a tire to prepare test tires having a tire size of 245 / 40R19.

[0141] [evaluation] The following evaluations were carried out for each of the obtained rubber compositions for tires and each of the test tires. When each of the obtained test tires was subjected to a braking test, the following braking test method was carried out by mounting four of each test tire on a passenger car having an engine displacement of 2300 cc.

[0142] [Performance on ice] The vehicle is driven on a test course with an icy road surface, and a professional test driver performs a feeling evaluation of braking / driving performance, lane changing performance, cornering performance, etc. This evaluation is based on an index rating with a standard example as the standard (100). The higher the index, the better the performance on ice.

[0143] [Snow performance] The vehicle is driven on a test course on snowy roads, and a professional test driver performs a feeling evaluation of braking / driving performance, lane changing performance, cornering performance, etc. This evaluation is an index evaluation based on a standard example (100). The higher the index, the better the performance on snow.

[0144] [Wet performance] In the wet braking test, the braking distance was measured from an initial speed of 100km / h on an asphalt road surface sprayed with water. The reciprocal of the distance was indexed with the standard example set at 100 and shown in Tables 3 and 4. In the present invention, wet performance is considered to be excellent when the index is over 100. A larger value indicates better wet performance.

[0145] [Green Intensity] Using each of the obtained rubber compositions (unvulcanized), JIS No. 3 dumbbell-shaped test pieces (thickness 2 mm) were punched out in accordance with JIS K6251:2017, and the 300% modulus was measured under conditions of a temperature of 20°C and a tensile speed of 500 mm / min. The 300% modulus was indexed with the standard example being 100, and is shown in Tables 3 to 4. In the present invention, green strength is considered to be excellent when the index is greater than 100. A higher value indicates better green strength.

[0146] [Table 3] [Table 4]

[0147] Details of each component in Tables 3 and 4 are as follows. NR: Natural rubber. SIR20 made by PT.KIRANA SAPTA, Tg: -65℃ Conjugated diene rubber 1 (for comparison): NS612 (solution-polymerized SBR, Tg: -60°C) manufactured by Zeon Co., Ltd. (does not satisfy formula (1) and therefore does not fall under the category of the specific conjugated diene rubbers described above) Conjugated diene rubber 2-3 (comparison): Conjugated diene rubber 2-3 synthesized as described above Conjugated diene rubber 4-5: Conjugated diene rubber 4-5 synthesized as described above BR: Nipol BR1220 (polybutadiene rubber, Tg: -106℃) manufactured by Nippon Zeon Co., Ltd.

[0148] · Plasticizer-containing BR1: BR extended with liquid BR. BRX5000, manufactured by Zeon Corporation. Contains 40 parts by mass of liquid (low molecular weight) BR at 25°C for every 100 parts by mass of solid BR at 25°C. The BR and liquid BR contained in plasticizer-containing BR1 are unmodified. Plasticizer C1 (liquid BR): Liquid butadiene rubber. Mw is 38,000. Liquid at 25°C. Plasticizer C2 (vegetable oil): Showa Pure Sunflower Oil Olein Rich, manufactured by Showa Sangyo Co., Ltd. It is liquid at 25°C.

[0149] Epichlorohydrin rubber: Hydrin C2000L manufactured by Zeon Co., Ltd., epichlorohydrin-ethylene oxide copolymer, Mooney viscosity at 100°C = 70)

[0150] Plasticizer C3 (thermoplastic resin): Terpene resin: Yasuhara Chemical YS Resin TO125 (aromatic modified terpene resin, softening point: 125°C) · Plasticizer-containing BR2: BR extended with liquid BR modified with aminopropyldimethoxysilyl groups. The plasticizer-containing BR2 was produced by mixing 100 parts by mass of BR (product name NIPOL BR 1220, manufactured by Zeon Corporation) that is solid at 25°C with 40 parts by mass of BR that is liquid (low molecular weight) at 25°C and has been modified with aminopropyldimethoxysilyl groups. The method for producing liquid BR modified with aminopropyldimethoxysilyl groups is as follows. A 5L autoclave was thoroughly dried and substituted with nitrogen, and 4,100g of hexane, 92mL of n-butyllithium (1.60mol / L hexane solution), and 0.25mL of 2,2-di(2-tetrahydrofuryl)propane were charged. Under stirring conditions, 762g of butadiene was successively added and polymerization was carried out at room temperature for 1 hour. Then, 59g of N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane was added to terminate the polymerization reaction, and a polymer solution was obtained. The resulting solution was taken out and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0L), and a modified liquid polymer was obtained by separating the methanol-insoluble components. The weight average molecular weight of the resulting modified polymer was 9,500. The resulting modified liquid polymer was BR, which has N-trimethylsilyl-3-iminopropyldimethoxysilyl groups as aminopropyldimethoxysilyl groups and is liquid under 25°C conditions.

[0151] Carbon black (HAF): Tokai Carbon Co., Ltd., Seast 3 (HAF carbon black, nitrogen adsorption specific surface area (N2SA): 79 m 2 / g) ·Silica: Solvay ZEOSIL 1165MP (CTAB adsorption specific surface area: 160m 2 / g) Silane coupling agent Si69: Evonik Si69 Stearic acid: NOF Corporation's Stearic Acid YR Beads Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. Anti-aging agent: EASTMAN 6PPD

[0152] Plasticizer C4 (oil): Aromatic oil. Extract No. 4 S manufactured by Showa Shell Sekiyu Co., Ltd. Liquid at 25°C Plasticizer C5: Liquid BR modified with aminopropyldimethoxysilyl groups. Produced in the same manner as the liquid BR modified with aminopropyldimethoxysilyl groups contained in the plasticizer-containing BR2.

[0153] Sulfur: Shikoku Chemical Industry Co., Ltd.'s Myucron OT-20 · Vulcanization accelerator CZ: Sancerer CM-G (sulfenamide type) manufactured by Sanshin Chemical Industry Co., Ltd. · Vulcanization accelerator DPG: Sumitomo Chemical Co., Ltd. Soxinol DG (guanidine type) · Vulcanization accelerator DPG (Sumitomo Chemical Co., Ltd. Soksil DG)

[0154] As can be seen from Tables 3 and 4, all of Examples 1 to 10, which contain a specific amount of a specific conjugated diene rubber, a specific amount of silica, and a specific amount of plasticizer (C), showed excellent performance on ice, performance on snow, wet performance, and green strength. Comparing Examples 1 and 2 (comparison between embodiments in which only the type of rubber component is different), Example 1 showed better performance on ice and on snow than Example 2. 10% and Mw 10% Example 2, which contained a specific conjugated diene rubber having a higher specific viscosity, exhibited better green strength than Example 1. In addition, comparing Example 1 with Examples 3, 4, and 7 (comparison of embodiments differing only in the type of plasticizer (C)), Examples 3 and 4, in which the plasticizer (C) contains a liquid polymer or vegetable oil, showed better on-ice and on-snow performance than Example 1. Example 3 also showed better green strength. Example 7, in which the plasticizer (C) contains a thermoplastic resin, showed better wet performance and green strength than Example 1. Furthermore, when the composition of the present invention contains BR as another rubber component, comparison of Example 1 with Examples 5 and 8 (comparison of embodiments differing only in whether BR is a mixture with a liquid polymer or not) shows that Examples 5 and 8, in which BR is a mixture with a liquid polymer, showed better on-ice performance, on-snow performance and green strength. In addition, comparing Example 3 with Example 9 (a comparison between two embodiments in which the liquid polymer is either unmodified or modified), Example 9, which contains a modified liquid polymer, showed better performance on ice. In addition, when the composition of the present invention contains BR as another diene rubber and the BR is a mixture with a liquid polymer, a comparison between Example 5 and Example 8 (a comparison between embodiments in which the liquid polymer is unmodified or modified) shows that Example 8, which contains a modified liquid polymer, exhibits better performance on ice, performance on snow, wet performance and green strength. Furthermore, comparing Example 1 and Example 6 (comparison between embodiments differing only in the amount of epichlorohydrin), Example 6, which further contained epichlorohydrin, showed superior performance on ice. Moreover, among Examples 1 to 10, Example 10, which contains vegetable oil and a thermoplastic resin as a plasticizer, contains BR as another diene rubber, and is a mixture of the BR with a modified liquid polymer, exhibited the best on-ice performance, on-snow performance, and green strength.

[0155] On the other hand, in the standard example containing conjugated diene rubber 1 (comparison) instead of the specific conjugated diene rubber, Comparative Examples 1 and 2 containing conjugated diene rubber 2 or 3 (comparison), which is a modified diene rubber other than the specific conjugated diene rubber, instead of the specific conjugated diene rubber, Comparative Example 3 in which the content of plasticizer (C) per 100 parts by mass of diene rubber is less than 30 parts by mass, Comparative Example 4 in which the content of plasticizer (C) per 100 parts by mass of diene rubber exceeds 80 parts by mass, Comparative Example 5 in which the content of silica per 100 parts by mass of diene rubber is less than 30 parts by mass, Comparative Example 6 in which the content of silica per 100 parts by mass of diene rubber exceeds 90 parts by mass, Comparative Example 7 in which the specific conjugated diene rubber is contained but its content in the diene rubber is 15% by mass or less, and Comparative Example 8 in which the specific conjugated diene rubber is contained but its content in the diene rubber exceeds 50% by mass, at least one of the performance on ice, performance on snow, wet performance, and green strength was insufficient. [Explanation of symbols]

[0156] 1 Bead section 2 Sidewall 3 Tire tread 4 Carcass layer 5 Bead Core 6 Bead Filler 7 Belt layer 8 Rim cushion

Claims

1. The composition contains a diene rubber including a modified conjugated diene rubber (A1), silica (B), and a plasticizer (C), The modified conjugated diene rubber (A1) satisfies the following formula (1) and the following formula (2) and has a modifying group containing 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 is more than 15 mass% and 50 mass% or less, the content of the silica (B) relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 90 parts by mass or less, The rubber composition for tires, wherein the content of the plasticizer (C) relative to 100 parts by mass of the diene rubber is 30 parts by mass or more and 80 parts by mass or less. 4.7≦IVw １０％ ≦3.1×10 －６ ×Mw １０％ -2.77 (1) St+Vn≦50 (2) Mw in formula (1) １０％ and IVw １０％ The details are as follows: The modified conjugated diene rubber is subjected to gel permeation chromatography measurement using a differential refractive index detector and a viscosity detector as detectors. The weight average molecular weight (Mw) was calculated using the high molecular weight portion of the chromatogram peak that was 10% of the total peak area. 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. 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.

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

3. The rubber composition for a tire according to claim 1, wherein the plasticizer (C) comprises at least one selected from the group consisting of oils, liquid polymers, and thermoplastic resins.

4. 2. The rubber composition for tires according to claim 1, wherein the plasticizer (C) contains at least one selected from the group consisting of liquid polymers and vegetable oils in an amount of 1 part by mass or more per 100 parts by mass of the diene rubber.

5. 2. The rubber composition for tires according to claim 1, wherein the diene rubber further comprises a mixture of SBR and / or BR with a liquid polymer.

6. The rubber composition for a tire according to claim 5 , wherein the liquid polymer contained in the mixture includes a modified liquid polymer.

7. 2. The rubber composition for tires according to claim 1, further comprising an epichlorohydrin rubber, the content of the epichlorohydrin rubber being 1 part by mass or more and 25 parts by mass or less per 100 parts by mass of the diene rubber.

8. 2. The rubber composition for tires according to claim 1, wherein the plasticizer (C) contains a thermoplastic resin, and the content of the thermoplastic resin is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the diene rubber.

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

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