Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires and tires that exhibit excellent rolling performance, wet performance, and snow performance. [Solution] 100 parts by mass of conjugated diene rubber containing aromatic vinyl-conjugated diene copolymer rubber and 140 m of CTAB 2 A rubber composition for tires containing 120 parts by mass or more of silica (1 / g or more), 25 parts by mass or more of resin, 20 parts by mass or more of plasticizing oil, and a silane coupling agent, wherein the parameter P is 2.4 or higher. JPEG2026083745000011.jpg5131 Here, Pol.Tg represents the Tg [°C] of the conjugated diene rubber, tanδ(Pol.Tg+70°C) represents the tanδ of the tire rubber composition at Tg+70°C, tanδ(Pol.Tg+130°C) represents the loss tangent of the tire rubber composition at Tg+130°C, and E′(Pol.Tg+70°C) represents the storage modulus [MPa] of the tire rubber composition at a temperature of Tg+70°C.

Description

[Technical Field]

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

[0002] Conventionally, rubber compositions for tires containing silica, resin, oil, etc., have been known from the viewpoint of improving performance (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-135762 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, from an environmental perspective, there has been a demand for further improvements in tire rolling performance. Furthermore, from a safety perspective, there is also a demand for further improvements in tire wet and snow performance. In this context, the inventors examined the tire rubber compositions described in Patent Document 1, etc., and found that further improvements are desirable considering the increasing demands that are expected in the future.

[0005] Therefore, in view of the above circumstances, the present invention aims to provide a tire rubber composition that exhibits excellent rolling performance, wet performance, and snow performance when made into a tire, and a tire manufactured using the above tire rubber composition. [Means for solving the problem]

[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 setting a specific parameter, which combines the loss tangent and the storage modulus, to a predetermined value or higher, and thus arrived at the present invention. In other words, the inventors have found that the above problem can be solved by the following configuration.

[0007] (1) 100 parts by mass of conjugated diene rubber containing aromatic vinyl-conjugated diene copolymer rubber, and 140 m of CTAB 2 It contains 120 parts by mass or more of silica (1 / g or more), 25 parts by mass or more of resin, 20 parts by mass or more of plasticizing oil, and a silane coupling agent. A rubber composition for tires in which the parameter P, described later, is 2.4 or higher. (2) The tire rubber composition according to (1) above, wherein 100 parts by mass of the conjugated diene rubber also contains 20 parts by mass or more of aromatic vinyl-conjugated diene copolymer rubber having an aromatic vinyl content of 33% by mass or less. (3) The tire rubber composition according to (1) or (2) above, wherein 100 parts by mass of the above-mentioned conjugated diene rubber contains 20 parts by mass or more of an aromatic vinyl-conjugated diene copolymer rubber that satisfies formula (1) described later. (4) The tire rubber composition according to any one of (1) to (3) above, wherein the silane coupling agent is a silane coupling agent having a protective mercapto group. (5) The above resin 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. A tire rubber composition according to any one of (1) to (4) above, wherein the ratio of the resin content to the plasticizing oil content is 1.0 or more by mass. (6) A tire manufactured using any of the tire rubber compositions described in (1) to (5) above. [Effects of the Invention]

[0008] As shown below, the present invention provides a tire rubber composition that exhibits excellent rolling performance, wet performance, and snow performance when made into a tire, 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. [Embodiments for Carrying out the Invention]

[0010] Hereinafter, the rubber composition for tires of the present invention and the like will be described. In addition, the numerical range represented by "~" in this specification means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. Each component may be used alone or in combination of two or more. Here, when two or more of each component are used in combination, the content of that component refers to the total content unless otherwise specified. In addition, for the rubber composition for tires, the rolling performance, wet performance, and snow performance when made into a tire are also simply referred to as "rolling performance", "wet performance", and "snow performance", respectively.

[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 100 parts by mass of a conjugated diene rubber containing an aromatic vinyl-conjugated diene copolymer rubber, 120 parts by mass or more of silica with a CTAB of 140 m 2 / g or more, 25 parts by mass or more of a resin, 20 parts by mass or more of a plasticized oil, and a silane coupling agent, and is a rubber composition for tires in which the parameter P described later is 2.4 or more.

[0012] Hereinafter, each component and the like contained in the composition of the present invention will be described.

[0013] [1] Conjugated diene rubber The conjugated diene rubber contained in the composition of the present invention includes aromatic vinyl-conjugated diene copolymer rubber. The conjugated diene rubber may also include conjugated diene rubber other than aromatic vinyl-conjugated diene copolymer rubber.

[0014] [Aromatic vinyl-conjugated diene copolymer rubber] Aromatic vinyl-conjugated diene copolymer rubber is a rubber made from a copolymer of aromatic vinyl and conjugated diene.

[0015] [Amjonomic vinyl] Specific examples of aromatic vinyls include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, divinylbenzene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, and vinylpyridine. Among these, styrene is preferred because it exhibits superior effects compared to the present invention.

[0016] [Conjugated diene] Specific examples of conjugated dienes include butadiene (e.g., 1,3-butadiene), isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and 1,3-pentadiene. Among these, 1,3-butadiene is preferred because it exhibits superior effects compared to the present invention.

[0017] [Specific examples] Specific examples of aromatic vinyl-conjugated diene copolymer rubbers include styrene-butadiene rubber (SBR) and styrene-isoprene rubber. Among these, SBR is preferred because it exhibits superior effects compared to the present invention.

[0018] [Ammonium vinyl content] The ratio of repeating units derived from aromatic vinyl (especially styrene) to the total aromatic vinyl-conjugated diene copolymer rubber (hereinafter also referred to as "aromatic vinyl content," and also as "styrene content" when the aromatic vinyl is styrene) is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, and even more preferably 20 to 33% by mass, for the reasons that the effects of the present invention are superior.

[0019] [Vinyl quantity] The ratio of repeating units of the 1,2-vinyl structure derived from the conjugated diene (especially butadiene) to the total aromatic vinyl-conjugated diene copolymer rubber (hereinafter also referred to as "vinyl amount") is preferably 1 to 70% by mass, more preferably 5 to 50% by mass, even more preferably 10 to 30% by mass, and particularly preferably 15 to 20% by mass, for which the effects of the present invention are superior.

[0020] [Content] The content of aromatic vinyl-conjugated diene copolymer rubber in 100 parts by mass of conjugated diene rubber is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 70 parts by mass or more, for reasons that the effects of the present invention are superior. The upper limit is not particularly limited, and is 100 parts by mass.

[0021] [Other conjugated diene rubbers] The conjugated diene rubber may include conjugated diene rubbers other than aromatic vinyl-conjugated diene copolymer rubber (hereinafter also referred to as "other conjugated diene rubbers"). Examples of such conjugated diene rubbers include natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Among these, butadiene rubber is preferred because it exhibits superior effects compared to the present invention.

[0022] [Content] The content of other conjugated diene rubbers in 100 parts by mass of conjugated diene rubber is preferably 50 parts by mass or less, and more preferably 30 parts by mass or less, for the reasons that the effects of the present invention are superior.

[0023] When the conjugated diene rubber contains butadiene rubber, the amount of butadiene rubber in 100 parts by mass of the conjugated diene rubber is preferably 10 to 40 parts by mass, and more preferably 20 to 30 parts by mass, for the reasons that the effects of the present invention are superior.

[0024] [Specific conjugated diene rubber] For reasons that the effects of the present invention are superior, it is preferable that the conjugated diene rubber contains a conjugated diene rubber that satisfies formula (1) described later (hereinafter also referred to as "specific conjugated diene rubber").

[0025] [Body structure] The backbone of specific conjugated diene rubbers is a polymer having repeating units derived from conjugated dienes.

[0026] <Conjugated Diene> Specific examples and preferred embodiments of the conjugated diene are the same as those of the conjugated diene in the aromatic vinyl-conjugated diene copolymer described above.

[0027] <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.

[0028] <Specific example> Specific examples of the rubber skeleton include natural rubber (NR), butadiene rubber (BR), aromatic vinyl-conjugated diene copolymer rubber, isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Examples of aromatic vinyl-conjugated diene copolymer rubbers include styrene-butadiene rubber (SBR) and styrene-isoprene rubber. The above-mentioned conjugated diene rubber is preferably an aromatic vinyl-conjugated diene copolymer rubber, and more preferably SBR, for the reasons that the effects of the present invention are superior.

[0029] [Specific modified group] The specific conjugated diene rubber is preferably one that has a modified group (specific modified group) containing a nitrogen atom, a silicon atom, and an oxygen atom adjacent to the silicon atom, for better performance of the present invention. The specific modified group is thought to interact with silica. 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.

[0030] [Formula (1)] A specific conjugated diene rubber is a conjugated diene rubber that 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 branches or with a relatively small molecular size for their molecular weight tend to satisfy Equation (1). The reason for limiting to the high molecular weight side is that the influence on the physical properties of the entire polymer is large.

[0031] IVw 10% ≦3.1×10 -6 ×Mw 10% -2.77 (1)

[0032] Mw in Equation (1) 10% and IVw 10% are determined as follows. For conjugated diene rubber, gel permeation chromatography measurement is performed using a differential refractive index detector (RI detector) and a viscosity detector as detectors. Among the peaks of the chromatogram by the differential refractive index detector, the weight-average molecular weight determined using the high molecular weight side portion that is 10% of the total area of the peak is defined as Mw 10% . Also, among the peaks of the chromatogram by the viscosity detector, the weight-average intrinsic viscosity determined using the high molecular weight side portion that is 10% of the total area of the peak is defined as IVw 10% . However, the unit of the weight-average intrinsic viscosity is dL / g.

[0033] Hereinafter, Mw 10% and IVw 10% in Equation (1) will be described more specifically.

[0034] As described above, for conjugated diene rubber, gel permeation chromatography (GPC) measurement is performed using a differential refractive index detector and a viscosity detector as detectors. The specific method of GPC measurement is as follows.

[0035] 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.

[0036] The weight-average molecular weight is determined using the high molecular weight side (shorter elution time) portion of the peak (peak originating from 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.

[0037] 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 peaks (peaks originating from conjugated diene rubbers), specifically the high molecular weight side (those with shorter elution times). 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.

[0038] 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, Mw 10% and IVw 10% We seek.

[0039] Methods for ensuring that the conjugated diene rubber satisfies formula (1) include, for example, changing the type and amount of specific modifier and the type and amount of specific branching agent in the manufacturing method of the present invention described later.

[0040] 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.

[0041] IVw 10% For reasons that the effects of the present invention are superior, the value is preferably 2 to 8, and more preferably 4 to 6.

[0042] [Formula (2)] The specific conjugated diene rubber is preferably one that satisfies the following formula (2) for the reason that the effects of the present invention are superior.

[0043] St + Vn ≤ 50 (2)

[0044] 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").

[0045] St+Vn is preferably 10 to 45, and more preferably 25 to 45, for better effects of the present invention.

[0046] 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.

[0047] Vn is preferably 5 to 30, and more preferably 10 to 20, for better effects of the present invention.

[0048] [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.

[0049] [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 performance 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.

[0050] [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).

[0051] [ka]

[0052] 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.

[0053] 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.

[0054] 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.

[0055] As described above, n represents an integer of 3 or greater. There is no particular upper limit to n, but it is preferable that it be 30 or less for the reasons that the effects of the present invention are superior.

[0056] [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.

[0057] [Content] The content of the specific conjugated diene rubber in 100 parts by mass of the conjugated diene rubber is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 70 parts by mass or more, for reasons that the effects of the present invention are superior. The upper limit is not particularly limited, and is 100 parts by mass.

[0058] [Average Tg] The glass transition temperature (hereinafter also referred to as "average Tg") of the entire conjugated diene rubber is preferably -100 to -30°C, more preferably -90 to -40°C, and even more preferably -80 to -50°C, for reasons that the effects of the present invention are superior. The above average Tg is the sum of the glass transition temperatures (Tg) of each component of the conjugated diene rubber multiplied by the mass fraction of each component (weighted average of glass transition temperatures). The method for measuring Tg is as described above.

[0059] [Molecular weight] The preferred embodiment of the weight-average molecular weight (Mw) of the conjugated diene rubber is the same as that of the specific conjugated diene rubber described above.

[0060] [2] Specific silica The composition of the present invention has a specific surface area of ​​cetyltrimethylammonium bromide (CTAB) adsorption (hereinafter also simply referred to as "CTAB") of 140 m². 2 It contains silica of / g or more (hereinafter also referred to as "specific silica"). The specific silica has a CTAB of 140m 2 Any conventionally known silica can be used as long as it is above / g.

[0061] [Specific example] 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.

[0062] [CTAB] As mentioned above, the CTAB of specific silica is 140m 2 It is 1 / g or more. The upper limit of CTAB for specific silica is not particularly limited, but 300m is preferred for better results in the present invention. 2 It is preferable that it be less than / g, and 250m 2 It is more preferable that it be less than or equal to / g, and 200m 2 It is even more preferable that the amount be less than or equal to / g. Here, the CTAB adsorption specific surface area is the value measured in accordance with JIS K6430:2008 Annex G.

[0063] [Content] In the composition of the present invention, the content of specific silica is 120 parts by mass or more per 100 parts by mass of the conjugated diene rubber described above. While there is no particular upper limit to the content of specific silica, for reasons that the effects of the present invention are superior, it is preferable that the content be 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less, per 100 parts by mass of the conjugated diene rubber described above.

[0064] [3] resin The composition of the present invention contains a resin (particularly a thermoplastic resin).

[0065] [Specific example] Examples of 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 esters, hydrogenated rosin derivatives), and terpene resins (e.g., terpene resin, modified terpene). Examples include 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 resins, 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.

[0066] [Preferred embodiment] The above resin preferably contains at least one selected from the group consisting of terpene resins, C5 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, for the reason that the effects of the present invention are superior, and more preferably contains at least one selected from the group consisting of terpene resins, C5 resins, C5 / C9 resins, and C9 resins. Hereinafter, a resin containing 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 will also be referred to as a "specific resin".

[0067] [Content] In the composition of the present invention, the resin content is 25 parts by mass or more per 100 parts by mass of the conjugated diene rubber described above. In particular, it is preferable that the resin content be 30 parts by mass or more, for which the effects of the present invention are superior. There is no particular upper limit to the content of the above resin, but for the reasons that the effects of the present invention are superior, it is preferable that the content be 100 parts by mass or less, and more preferably 80 parts by mass or less, per 100 parts by mass of the above-mentioned conjugated diene rubber.

[0068] [4] Plasticizing oil The composition of the present invention contains a plasticizing oil (hereinafter also simply referred to as "oil").

[0069] [Specific example] There are no particular restrictions on the type of oil used; specific examples include mineral oil and vegetable oil. Specific examples of mineral oils include paraffinic, naphthenic, and aromatic oils. Specific examples of vegetable oils include soybean oil, rapeseed oil, coconut oil, and linseed oil.

[0070] [Content] In the composition of the present invention, the oil content is 20 parts by mass or more per 100 parts by mass of the conjugated diene rubber described above. There is no particular upper limit to the content of the above oil, but for the reasons that the effects of the present invention are superior, it is preferable that the amount is 100 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of the above-mentioned conjugated diene rubber.

[0071] In the composition of the present invention, the ratio (mass ratio) of the content of the above-mentioned resin (particularly a specific resin) to the content of the oil is preferably 1.0 or higher, and more preferably 1.5 or higher, for the reasons that the effects of the present invention are superior. There is no particular upper limit, but for the reasons that the effects of the present invention are superior, it is preferably 5.0 or lower, and more preferably 3.0 or lower.

[0072] [5] Silane coupling agents The composition of the present invention contains a silane coupling agent. 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. Silane coupling agents may be used individually or in combination of two or more types.

[0073] [Hydrolyzable group] The above hydrolyzable group is not particularly limited, but examples include alkoxy groups, phenoxy groups, carboxyl groups, and alkenyloxy groups. Among these, an alkoxy group is preferred because it provides superior effects of the present invention. When the hydrolyzable group is an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 16, and more preferably 1 to 4, for superior effects of the present invention. Examples of alkoxy groups with 1 to 4 carbon atoms include methoxy groups, ethoxy groups, and propoxy groups.

[0074] [Organic functional group] The above organic functional groups are not particularly limited, but are preferably groups that can form chemical bonds with organic compounds. Examples include epoxy groups, vinyl groups, acryloyl groups, methacryloyl groups, amino groups, sulfide groups, mercapto groups, and blocked mercapto groups (protected mercapto groups) (e.g., octanoylthio groups). Among these, sulfide groups (especially disulfide groups and tetrasulfide groups), mercapto groups, and blocked mercapto groups are preferred because they provide superior effects for the present invention.

[0075] [Specific example] Specific examples of silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazoletetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide, and 3-octanoylthio-1-propyltriethoxysilane. One of these may be used alone, or two or more may be used in combination.

[0076] [Preferred embodiment] For reasons that the effects of the present invention are superior, the silane coupling agent is preferably a silane coupling agent having a protected mercapto group (hereinafter also referred to as "specific silane coupling agent"). A specific example of a particular silane coupling agent is the aforementioned 3-octanoylthio-1-propyltriethoxysilane.

[0077] [Content] In the composition of the present invention, the content of the silane coupling agent is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferable that the content be 2 to 20 parts by mass per 100 parts by mass of the conjugated diene rubber described above.

[0078] Furthermore, in the composition of the present invention, the content of the 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. [6] Optional component The composition of the present invention may optionally contain components other than those described above (optional components). Examples of such components include silica other than specific silica, fillers other than silica (preferably carbon black), thermally expandable microcapsules, zinc oxide (zinc oxide), stearic acid, antioxidants, waxes, processing aids, liquid polymers, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), vulcanization activators, and various other additives commonly used in rubber compositions.

[0079] [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.

[0080] [N2SA] The nitrogen adsorption specific surface area (N2SA) of the carbon black described above is not particularly limited, but for reasons that the effects of the present invention are superior, it is 50 to 200 m². 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".

[0081] [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 conjugated diene rubber described above.

[0082] [7] Parameter P The composition of the present invention has a parameter P (hereinafter also referred to as "P value") of 2.4 or higher. Furthermore, methods for achieving a P-value of 2.4 or higher include, for example, selecting a suitable embodiment for each of the components mentioned above.

[0083]

number

[0084] Here, Pol.Tg represents the glass transition temperature [°C] of the conjugated diene rubber described above, tanδ(Pol.Tg+70°C) represents the loss tangent of the tire rubber composition at a temperature of Pol.Tg+70°C, tanδ(Pol.Tg+130°C) represents the loss tangent of the tire rubber composition at a temperature of Pol.Tg+130°C, and E′(Pol.Tg+70°C) represents the storage modulus [MPa] of the tire rubber composition at a temperature of Pol.Tg+70°C.

[0085] Pol.Tg is the glass transition temperature of the entire conjugated diene rubber as described above, and is the same as the average Tg mentioned above.

[0086] The loss tangent and storage modulus of the tire rubber composition are values ​​obtained after vulcanization. The vulcanization conditions are 160°C for 20 minutes.

[0087] The loss tangent and storage modulus are measured as follows: A vulcanized rubber sheet is prepared using the vulcanization conditions described above. The obtained vulcanized rubber sheet was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K6394:2007, under the conditions of a tensile deformation strain of 10% ± 0.1%, a frequency of 20 Hz, and temperatures of Pol.Tg + 70°C and Pol.Tg + 130°C. The loss tangent was then determined from the storage modulus and loss modulus.

[0088] [tanδ(Pol.Tg+70℃)-tanδ(Pol.Tg+130℃)] The ratio of tanδ(Pol.Tg+70℃)-tanδ(Pol.Tg+130℃) is preferably 0.02 or higher, more preferably 0.04 or higher, even more preferably 0.06 or higher, and particularly preferably 0.08 or higher, for reasons that the effects of the present invention are superior. There is no particular upper limit, but for reasons that the effects of the present invention are superior, it is preferably 0.50 or lower, and more preferably 0.30 or lower.

[0089] [E'(Pol.Tg+70℃)] E'(Pol.Tg+70℃) is preferably 40 MPa or higher, and more preferably 50 MPa or higher, for better performance of the present invention. There is no particular upper limit, but it is preferably 100 MPa or lower, and more preferably 70 MPa or lower.

[0090] [P-value] As mentioned above, the p-value is 2.4 or higher. The p-value is preferably 3.0 or higher, and more preferably 4.0 or higher, for the sake of superior effects of the present invention. There is no particular upper limit, but it is preferably 10.0 or lower, and more preferably 8.0 or lower, for the sake of superior effects of the present invention.

[0091] [8] Method for preparing a 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.

[0092] [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.

[0093] 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.

[0094] 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.

[0095] 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]

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0097] [Synthesis of specific conjugated diene rubbers] The following specific conjugated diene rubbers 1 and 2 were synthesized.

[0098] [Specific conjugated diene rubber 1]

[0099] <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 0.023 g / h, 1,3-butadiene at 176.4 g / h, 1-butene at 0.406 g / h, and styrene at 23.6 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 0.02 g / h, and the reaction was carried out with stirring. The branching agent is the specific branching agent mentioned above.

[0100] <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 0.08 g / h, and the mixture was stirred to allow the reaction to proceed.

[0101] Subsequently, methanol was added as a polymerization inhibitor to obtain a solution containing conjugated diene rubber.

[0102] 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 specific conjugated diene rubber 1.

[0103] Specific 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, and is a conjugated diene rubber having a modifying group (specific modifying group) containing a nitrogen atom, a silicon atom, and an adjacent oxygen atom, derived from the modifying agent. The specific 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).

[0104] [Specific conjugated diene rubber 2] 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 specific conjugated diene rubber 1. The obtained conjugated diene rubber is also called specific conjugated diene rubber 2.

[0105] Specific conjugated diene rubber 2 is a reaction product of a conjugated diene polymer, which is a copolymer of butadiene, styrene, and a branching agent, and a modifying agent, and is a conjugated diene rubber having a modifying group (specific modifying group) containing nitrogen atoms, silicon atoms, and adjacent oxygen atoms derived from the modifying agent. The specific conjugated diene rubber 2 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).

[0106] [Table 1]

[0107] [Weight-average molecular weight, weight-average intrinsic viscosity, styrene content, vinyl content, glass transition temperature] As described above, for the specific conjugated diene rubbers 1 and 2 synthesized, Mw, Mw 10% , IVw, IVw 10% Table 2 shows the St, Vn, and glass transition temperature (Tg). Similarly, Table 2 also shows the values ​​for NS612, NS616, and HP755B, which will be discussed later. 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.

[0108] [Table 2]

[0109] As shown in Table 2, both Specified Conjugated Diene Rubbers 1 and 2 are conjugated diene rubbers that satisfy formula (1), and therefore correspond to the Specified Conjugated Diene Rubbers described above. Furthermore, both Specified Conjugated Diene Rubbers 1 and 2 correspond to aromatic vinyl-conjugated diene copolymer rubbers. In other words, both Specified Conjugated Diene Rubbers 1 and 2 are aromatic vinyl-conjugated diene copolymer rubbers that satisfy formula (1). On the other hand, as shown in Table 2, NS612, NS616, and HP755B do not satisfy formula (1) and therefore do not fall under the category of the specified conjugated diene rubbers mentioned above.

[0110] [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. As will be described later, HP755B is an oil-extracted product, and the rubber content of HP755B in Example 9 is 40 parts by mass.

[0111] [evaluation] Using each of the obtained tire rubber compositions, test tires were fabricated in tire size 245 / 40R19. The following evaluations were then performed on each test tire.

[0112] [Rolling performance] The test tire was mounted on a wheel with a rim size of 18 x 7.5J, the air pressure was set to 210 kPa, and the rolling resistance was measured when the tire was pressed against the drum using an indoor drum testing machine (drum diameter: 1707 mm) with a load equivalent to 85% of the maximum load at that air pressure as described in the JATMA Yearbook 2009 edition, and the machine was driven at a speed of 80 km / h (hour). The results are shown in Tables 3-5. The evaluation results are expressed as an index using the reciprocal of the measured value, with Example 1 set to 100. A larger index value indicates lower rolling resistance and superior rolling performance. In practical terms, an index of 90 or higher is preferable.

[0113] [Wet performance] Four test tires were mounted on a passenger car with a 2300cc engine, and the braking distance from an initial speed of 100 km / h (in hours) was measured on a water-sprayed asphalt surface. The reciprocal of the distance was then indexed, with Example 1 set to 100. The results are shown in Tables 3-5. A higher index indicates better wet performance. In practical terms, an index of 90 or higher is preferable.

[0114] [Snow performance] Four test tires were mounted on a passenger car with a 2300cc engine, and the braking distance was measured on a compacted snow surface starting from an initial speed of 40 km / h. The reciprocal of the braking distance was then indexed, with Example 1 set to 100. The results are shown in Tables 3-5. A higher index indicates better snow performance. In practical terms, an index of 90 or higher is preferable.

[0115] [Table 3]

[0116] [Table 4]

[0117] [Table 5]

[0118] The details of each component in Tables 3-5 are as follows. • Specific conjugated diene rubber 1-2: Specific conjugated diene rubber 1-2 synthesized as described above. • NS612: NS612 manufactured by Nippon Zeon Co., Ltd. (solution polymerized SBR, aromatic vinyl content (styrene content): 15% by mass, Tg: -60℃) (does not satisfy formula (1) and therefore does not fall under the category of the specified conjugated diene rubber mentioned above) • NS616: NS616 manufactured by Nippon Zeon Co., Ltd. (end-modified solution polymerized SBR, aromatic vinyl content (styrene content): 22% by mass, Tg: -23℃) (does not satisfy formula (1) and therefore does not fall under the category of the specified conjugated diene rubber mentioned above) • HP755B: ENEOS Corporation HP755B (SBR, aromatic vinyl content (styrene content): 40% by mass, Tg: -30℃, oil spreadability: 37.5 parts by mass per 100 parts by mass of SBR) (Does not satisfy formula (1) and therefore does not fall under the category of the specified conjugated diene rubber mentioned above) • BR1220: Nipol BR1220 (butadiene rubber, Tg: -105℃) manufactured by Nippon Zeon Co., Ltd. ·Silica: Solvay ZEOSIL 1165MP (CTAB adsorption specific surface area: 160m 2 (corresponds to the specific silica mentioned above) • CB: Cabot Japan Co., Ltd. Show Black N339 (Carbon Black) • Resin A: YS Resin TO125 (aromatic modified terpene resin) manufactured by Yasuhara Chemical Co., Ltd. • Resin B: HC-3100 (C5 / C9 resin) manufactured by Guangzhou Ecopower New Material Co., Ltd. • Resin C: Mitsubishi Chemical Corporation FTR6100 (C5 series resin) • Silane coupling agent A: 3-octanoylthiopropyltriethoxysilane (the compound listed below) (corresponds to the specified silane coupling agent mentioned above)

[0119] [ka] • Silane coupling agent B: Si69 manufactured by Evonik (does not fall under the category of the specified silane coupling agent mentioned above) • Oil: Shell Lubricants Japan Extract No. 4 S • Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. • Stearic acid: NOF Corporation, Beads Stearic Acid YR • Anti-aging agent: Flexis 6PPD • Sulfur: Finely powdered sulfur containing Kinka oil, manufactured by Tsurumi Chemical Industry Co., Ltd. • Vulcanization accelerator (CZ): Noxellar CZ-G (CZ), manufactured by Ouchi Shinko Chemical Industry Co., Ltd. • Vulcanization accelerator (DPG): Sumitomo Chemical Co., Ltd.'s Soccinol DG (DPG)

[0120] In addition, the terms "Pol.Tg[℃]", "tanδ(Pol.Tg+70℃)", "tanδ(Pol.Tg+130℃)", "E′(Pol.Tg+70℃)[MP]" and "P-value" in Tables 3-5 are as described above.

[0121] As can be seen from Tables 3-5, Examples 1-10, which contained specific amounts of specific silica, resin, plasticizing oil, and silane coupling agent and had a P value of 2.4 or higher, showed excellent rolling performance, wet performance, and snow performance. Among these, Examples 1-6 and Examples 8-9, which had a P value of 3.0 or higher, showed even better snow performance. Among these, Examples 1-6 and Example 8, which had a P value of 3.3 or higher, showed even better snow performance. Among these, Examples 1-6, which had a P value of 3.5 or higher, showed even better rolling performance. Among these, Examples 1-5, which had a P value of 4.0 or higher, showed even better wet performance. Among these, Examples 1, 3, and 5, which had a P value of 4.5 or higher, showed even better rolling performance and snow performance. Among these, Examples 3 and 5, which had a P value of 5.0 or higher, showed even better rolling performance and snow performance. Among these, Example 3, with a P-value of 5.3 or higher, demonstrated even superior rolling and snow performance. Furthermore, a comparison of Examples 1 to 10 showed that Examples 1 to 9, in which the silane coupling agent was a specific silane coupling agent, exhibited superior snow performance. Furthermore, a comparison of Examples 1 to 9 (comparison of embodiments in which the silane coupling agent is a specific silane coupling agent) showed that Examples 1 to 6 and Example 8, which contain 20 parts by mass or more of aromatic vinyl-conjugated diene copolymer rubber satisfying formula (1), exhibited superior snow performance. Furthermore, a comparison between Example 2 and Example 9 (comparison of embodiments containing 35 parts by mass of resin B) showed that Example 2, which contains 20 parts by mass or more of aromatic vinyl-conjugated diene copolymer rubber with an aromatic vinyl content of 33% by mass or less, or 20 parts by mass or more of aromatic vinyl-conjugated diene copolymer rubber satisfying formula (1), exhibited superior rolling performance, wet performance, and snow performance. Furthermore, a comparison of Examples 1-5 (comparison of embodiments differing only in the type of resin) showed that Examples 1 and 3-5, which contain terpene resin or C5-based resin, exhibited superior rolling and snow performance. In particular, Examples 3 and 5, which contain C5-based resin, showed even superior rolling and snow performance. Among these, Example 3, in which the C5-based resin content was 30 parts by mass or more per 100 parts by mass of conjugated diene rubber, showed even superior rolling and snow performance.

[0122] On the other hand, Comparative Examples 1-6, which had a P-value of less than 2.4, had insufficient wet or snow performance. [Explanation of Symbols]

[0123] 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. 100 parts by mass of conjugated diene rubber containing aromatic vinyl-conjugated diene copolymer rubber, and 140 m of CTAB ２ It contains 120 parts by mass or more of silica (1 / g or more), 25 parts by mass or more of resin, 20 parts by mass or more of plasticizing oil, and a silane coupling agent. A rubber composition for tires in which the following parameter P is 2.4 or higher. [Math 1] Here, Pol. Tg represents the glass transition temperature [°C] of the conjugated diene rubber, tanδ(Pol. Tg + 70°C) represents the loss tangent of the tire rubber composition at a temperature of Pol. Tg + 70°C, tanδ(Pol. Tg + 130°C) represents the loss tangent of the tire rubber composition at a temperature of Pol. Tg + 130°C, and E'(Pol. Tg + 70°C) represents the storage modulus [MPa] of the tire rubber composition at a temperature of Pol. Tg + 70°C.

2. The tire rubber composition according to claim 1, wherein 100 parts by mass of the conjugated diene rubber comprises 20 parts by mass or more of aromatic vinyl-conjugated diene copolymer rubber having an aromatic vinyl content of 33% by mass or less.

3. The tire rubber composition according to claim 1, wherein 100 parts by mass of the conjugated diene rubber comprises 20 parts by mass or more of an aromatic vinyl-conjugated diene copolymer rubber satisfying the following formula (1). [Vw １０％ ≦3.1×10 －６ ×Mw １０％ -2.77 (1) Mw in equation (1) １０％ and IVw １０％ The details are as follows: Gel permeation chromatography measurements will be performed on aromatic vinyl-conjugated diene copolymers using a differential refractive index detector and a viscosity detector. 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.

4. The tire rubber composition according to claim 1, wherein the silane coupling agent is a silane coupling agent having a protective mercapto group.

5. The resin comprises 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 1, wherein the ratio of the resin content to the plasticizing oil content is 1.0 or more by mass.

6. A tire manufactured using the tire rubber composition described in any one of claims 1 to 5.

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