Tire rubber composition and tire

Abstract

The present invention addresses the problem of providing: a tire rubber composition that, when formed into a tire, exhibits excellent wet grip performance and rolling resistance performance; and a tire produced using the tire rubber composition. A tire rubber composition according to the present invention contains 100 parts by mass of a rubber component containing a styrene-butadiene rubber, a resin that is a polymer of a monomer containing a C9 component and that has a parameter S1 of at least 18.0, and 10-300 parts by mass of silica. The contained amount of the resin is 1-200 mass% with respect to the contained amount of the styrene-butadiene rubber.　S1 = (P / 10)5 / Mz, where P represents the polarizability of the C9 component, and Mz represents the z-average molecular weight of the resin.

Description

Rubber composition for tires, and tires

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

[0002] Conventionally, rubber compositions for tires containing petroleum resins are known from the viewpoint of controlling properties such as viscoelasticity (for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2007-277307

[0004] Recently, from the perspective of safety and environmental issues, there is a demand for achieving a high level of both wet grip performance and rolling resistance performance. In this context, when the present inventors examined the tire rubber composition described in the example of Patent Document 1, it became clear that the performance when made into a tire is not always sufficient.

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

[0006] The inventors of the present invention, after diligently studying the above problems, discovered that the above problems could be solved by blending a specific resin in a predetermined ratio, and thus arrived at the present invention. In other words, the inventors of the present invention discovered that the above problems could be solved by the following configuration.

[0007] (1) A tire rubber composition comprising 100 parts by mass of a rubber component containing styrene-butadiene rubber, a resin which is a polymer of a monomer containing a C9 component and has the following parameter S1 of 18.0 or higher, and 10 to 300 parts by mass of silica, wherein the content of the resin is 1 to 200% by mass relative to the content of the styrene-butadiene rubber. S1 = (P / 10) ５ / Mz Here, P represents the polarizability of the C9 component, and Mz represents the z-average molecular weight of the resin. (2) The tire rubber composition according to (1) above, wherein the parameter S1 is greater than 25.0. (3) A tire manufactured using the tire rubber composition according to (1) or (2) above.

[0008] As described below, the present invention provides a tire rubber composition that exhibits excellent wet grip performance and rolling resistance performance when made into a tire, as well as a tire manufactured using the above tire rubber composition.

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

[0010] The present invention's rubber composition for tires is described below. In this specification, numerical ranges expressed using "~" mean a range that includes the values ​​before and after "~" as the lower and upper limits. Each component may be used alone or in combination of two or more. When two or more components are used in combination, the content of each component refers to the total content unless otherwise specified. Furthermore, with respect to the rubber composition for tires, the wet grip performance and rolling resistance performance when made into a tire are also simply referred to as "wet grip performance" and "rolling resistance characteristics," 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") contains 100 parts by mass of a rubber component containing styrene-butadiene rubber, a resin (hereinafter also referred to as "specific resin") which is a polymer of a monomer containing a C9 component and has a parameter S1 (hereinafter also simply referred to as "S1") described later of 18.0 or more, and 10 to 300 parts by mass of silica, wherein the content of the resin is 1 to 200% by mass relative to the content of the styrene-butadiene rubber.

[0012] The composition of the present invention is thought to be able to solve the above-mentioned problems by having such a structure. The reason is not clear, but it is speculated to be as follows. As described above, the composition of the present invention is a polymer of monomers containing a C9 component and contains a resin (specific resin) in which S1 is 18.0 or higher, as described later. The C9 component constituting the specific resin is thought to interact with the styrene units of styrene-butadiene rubber through π-π interactions. Here, since the specific resin has an S1 of 18.0 or higher, it has a small molecular weight and tends to have a high polarizability of the C9 component. Therefore, the π-π interaction is extremely strong, and the compatibility between the specific resin and SBR is extremely high. As a result, the composition of the present invention is thought to be a homogeneous composition and exhibit excellent wet grip performance and rolling resistance performance.

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

[0014] [1] Rubber component The composition of the present invention contains a rubber component including styrene-butadiene rubber (SBR). The above rubber component may also contain rubber components other than SBR. The rubber component may be modified with alkoxy groups, alkoxysilyl groups, etc. The rubber component does not contain any specific resin.

[0015] [SBR] SBR is a copolymer of styrene and butadiene.

[0016] [Styrene Content] The styrene content of SBR is not particularly limited, but it is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass, for the reasons that the effects of the present invention are superior. Here, the styrene content is the percentage (by mass) of repeating units derived from styrene relative to the total SBR.

[0017] [Vinyl Unit Content] The vinyl unit content of SBR is not particularly limited, but it is preferably 20 to 60 mol%, and more preferably 20 to 50 mol%, for the reasons that the effects of the present invention are superior. Here, vinyl unit content refers to the proportion (mol%) of 1,2-vinyl unit bond repeating units among the repeating units derived from butadiene in SBR.

[0018] [Glass Transition Temperature] The glass transition temperature (Tg) of SBR is not particularly limited, but for reasons that the effects of the present invention are better, it is preferably -85°C to -10°C, and more preferably -50°C to -20°C. The glass transition temperature can be adjusted, for example, by the styrene content or vinyl unit content. In this specification, the glass transition temperature (Tg) is calculated using the midpoint method by measuring with a differential scanning calorimeter (DSC) at a heating rate of 10°C / min.

[0019] [Content] The content of SBR in the rubber component is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, particularly preferably 70% by mass or more, and most preferably 90% by mass or more, for the reasons that the effects of the present invention are superior. The rubber component may consist only of SBR. Multiple SBRs may be used in combination.

[0020] [Other Rubber Components] The rubber component may include rubber components other than SBR (other rubber components). Examples of such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). Among these, NR and BR are preferred because they provide superior effects for the present invention.

[0021] [Average Tg] The glass transition temperature of the entire rubber component (hereinafter also referred to as "average Tg") is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferably -100°C to -20°C, and more preferably -80°C to -20°C. Here, the average Tg of the rubber component is the sum of the glass transition temperatures (Tg) of each rubber component multiplied by the mass fraction of each rubber component (weighted average value of glass transition temperatures).

[0022] [Molecular Weight] The weight-average molecular weight (Mw) of the rubber component is preferably 100,000 to 10,000,000, and more preferably 300,000 to 3,000,000, for the sake of superior effects of the present invention. Furthermore, the number-average molecular weight (Mn) of the rubber component contained in the composition of the present invention is preferably 50,000 to 5,000,000, and more preferably 150,000 to 1,500,000, for the sake of superior effects of the present invention. It is preferable that the Mw and / or Mn of at least one rubber component contained in the rubber component fall within the above range, and it is more preferable that the Mw and / or Mn of all rubber components contained in the rubber component fall within the above range. In this specification, Mw and Mn are standard polystyrene equivalent values ​​obtained by gel permeation chromatography (GPC) measurement under the following conditions: Solvent: Tetrahydrofuran Detector: RI detector

[0023] [2] Specific Resin The composition of the present invention is a polymer of monomers containing a C9 component and contains a resin (specific resin) in which the parameter S1 described later is 18.0 or higher. The Mw of the specific resin is preferably less than 100,000 and more preferably 50,000 or lower for the reasons that the effects of the present invention are superior.

[0024] [Monomer] A specific resin is a polymer of monomers containing the C9 component.

[0025] [C9 Components] C9 components are the components contained in the so-called C9 fraction. Specific examples include styrene, methylstyrene (α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene), vinyltoluene (o-vinyltoluene, m-vinyltoluene, p-vinyltoluene), isopropenyltoluene (o-isopropenyltoluene, m-isopropenyltoluene, p-isopropenyltoluene), indene, methylindene, etc.

[0026] [Monomers other than C9 component] There are no particular restrictions on monomers below the C9 component, but specific examples include C4 components (C4 fractions) such as coumarone, dicyclopentadiene (DCPD), and butadiene, and C5 components (C5 fractions) such as isoprene.

[0027] [Percentage of C9 component] The percentage of the C9 component in the monomer is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, particularly preferably 70% by mass or more, and most preferably 90% by mass or more, for reasons that the effects of the present invention are superior. There is no particular upper limit, and it is 100% by mass.

[0028] [Parameter S1] The specific resin has the following parameter S1 of 18.0 or higher.

[0029] S1 = (P / 10) ５ / Mz Here, P represents the polarizability of the C9 component (the C9 component constituting the specific resin), and Mz represents the z-average molecular weight of the specific resin.

[0030] For reasons that the effects of the present invention are superior, S1 is preferably greater than 18.0, more preferably greater than 23.0, even more preferably greater than 25.0, particularly preferably 30.0 or more, and most preferably 40.0 or more. The upper limit of S1 is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferably 100.0 or less, and more preferably 70.0 or less.

[0031] [Polarization] The polarization of the C9 component described above is preferably 80 or higher, more preferably 85 or higher, even more preferably 90 or higher, particularly preferably 95 or higher, and most preferably 100 or higher, for reasons that the effects of the present invention are superior. There is no particular upper limit to the polarization, but for reasons that the effects of the present invention are superior, it is preferably 150 or lower, more preferably 130 or lower, and even more preferably 110 or lower.

[0032] Provided that when the specific resin is a polymer of monomers containing two or more types of C9 components, the polarizability of the C9 components for the specific resin refers to the sum of the polarizability of each C9 component multiplied by the mole fraction of each C9 component.

[0033] The polarizability described above can be obtained after structural optimization by quantum chemical calculation using Gaussian. The quantum chemical calculation is performed by the density functional B3LYP method using 3-21G as the basis function. In the present specification, the unit of the polarizability described above is au. 1 au is 1.648777×10 －４１ C ２ m ２ J －１ .

[0034] [Z-average molecular weight] The z-average molecular weight (Mz) of the specific resin is preferably less than 100,000, more preferably 50,000 or less, still more preferably 10,000 or less, particularly preferably 4,000 or less, and most preferably 3,000 or less, for the reason that the effect of the present invention is more excellent. The lower limit of Mz of the specific resin is not particularly limited, but is preferably 1,000 or more, and more preferably 2,000 or more, for the reason that the effect of the present invention is more excellent.

[0035] The z-average molecular weight (Mz) described above shall be measured under the following conditions. Apparatus: Gel permeation chromatography [GPC: HLC-8020 manufactured by Tosoh Corporation] Column: GMH-HR-H manufactured by Tosoh Corporation (two columns connected in series) Measurement temperature: 40°C Carrier: Tetrahydrofuran Flow rate: 1.0 mL / min Sample: 10 mg dissolved in 10 mL of THF (tetrahydrofuran) Injection volume: 10 μL Detector: Differential refractometer (RI-8020)

[0036] [Calculation Example] A calculation example of S1 is shown below. In the case of Resin 8 used in Example 1 described later, the polarizability of the C9 component (α-methylstyrene) is 93, and Mz is 3,500, so S1=(93 / 10) ５ / 3,500 = 19.9.

[0037] [Content] In the composition of the present invention, the content of the specific resin is 1 to 200% by mass relative to the content of the SBR described above. Among these, for the reason that the effect of the present invention is more excellent, the content is preferably 10 to 150% by mass, more preferably 10 to 100% by mass, still more preferably 20 to 70% by mass, and particularly preferably 30 to 50% by mass. Further, in the composition of the present invention, for the reason that the effect of the present invention is more excellent, the content of the specific resin is preferably 1 to 200 parts by mass, more preferably 10 to 150 parts by mass, still more preferably 10 to 100 parts by mass, particularly preferably 20 to 70 parts by mass, and most preferably 30 to 50% by mass, relative to 100 parts by mass of the rubber component described above. Further, in the composition of the present invention, for the reason that the effect of the present invention is more excellent, the content of the specific resin is preferably 1 to 200% by mass, more preferably 10 to 150% by mass, still more preferably 10 to 100% by mass, particularly preferably 20 to 70% by mass, and most preferably 30 to 50% by mass, relative to the content of silica described later.

[0038] [3] Silica The composition of the present invention contains silica. Silica is not particularly limited, and any conventionally known silica can be used. Examples of silica include wet silica, dry silica, fumed silica, diatomaceous earth, and the like. Biomass-derived silica such as rice hull may also be used. One type of the above silicas may be used alone, or two or more types of silicas may be used in combination.

[0039] [CTAB] The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of silica (hereinafter, "CTAB adsorption specific surface area" is also simply referred to as "CTAB") is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is 70 to 300 m ２ / g, preferably 110 to 250 m ２ / g, and more preferably. Here, the CTAB adsorption specific surface area is a value measured in accordance with JIS K6430:2008 Annex G.

[0040] [Content] In the composition of the present invention, the silica content is 10 to 300 parts by mass per 100 parts by mass of the rubber component described above. The above content is preferably 30 to 200 parts by mass, and more preferably 50 to 150 parts by mass, for the reason that the effects of the present invention are better.

[0041] [4] Optional Components The compositions of the present invention may optionally contain components other than those described above (optional components). Examples of such components include resins other than the specified resins, fillers other than silica (preferably carbon black or aluminum hydroxide), silane coupling agents, thermally expandable microcapsules, zinc oxide, stearic acid, antioxidants, waxes, processing aids, liquid polymers, thermosetting resins, vulcanizing agents (e.g., sulfur), vulcanization accelerators (accelerators), vulcanization activators, and various other additives commonly used in rubber compositions.

[0042] [Carbon Black] The composition of the present invention preferably contains carbon black for the reason that the effects of the present invention are superior. 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 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, SRF, etc. can be used.

[0043] [N ２ SA) Nitrogen adsorption specific surface area of ​​the above carbon black (N ２ SA) is not particularly limited, but 50 to 200 m is preferred for better effects of the present invention. ２ It is preferable that the amount be / g, and 70 to 150m ２ It is more preferable that the value is / 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".

[0044] [Content] In the composition of the present invention, the content of carbon black is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferably 1 to 130 parts by mass, more preferably 2 to 100 parts by mass, and even more preferably 5 to 50 parts by mass, per 100 parts by mass of the rubber component described above.

[0045] [Silane Coupling Agent] The composition of the present invention preferably contains a silane coupling agent because it provides superior effects.

[0046] The silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. The hydrolyzable group is not particularly limited, but examples 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, because it provides superior effects of the present invention. Examples of alkoxy groups having 1 to 4 carbon atoms include methoxy groups, ethoxy groups, and propoxy groups.

[0047] 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. The silane coupling agent may be used alone or in combination of two or more types.

[0048] The silane coupling agent described above is preferably a sulfur-containing silane coupling agent because it provides superior effects in the present invention.

[0049] Specific examples of the silane coupling agents mentioned above 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, 3-octanoylthio-1-propyltriethoxysilane, and polysiloxanes represented by the average composition formula of formula (1) below (hereinafter also referred to as "specific polysiloxanes"). One of these may be used alone, or two or more may be used in combination.

[0050] (A) ａ (B) ｂ (C) ｃ (D) ｄ (R １ ) ｅ SiO （４－２ａ－ｂ－ｃ－ｄ－ｅ）／２ (1) In formula (1), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 20 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R １ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. a to e satisfy the following relationships: 0 < a < 1, 0 < b < 1, 0 < c < 3, 0 ≤ d < 1, 0 ≤ e < 2, 0 < 2a + b + c + d + e < 4.

[0051] [Content] In the composition of the present invention, the content of the silane coupling agent relative to the silica content described above is preferably 1 to 20% by mass, and more preferably 5 to 15% by mass, for the reason that the effects of the present invention are superior.

[0052] Furthermore, in the composition of the present invention, the content of the silane coupling agent is preferably 2 to 20 parts by mass per 100 parts by mass of the rubber component described above, for the reason that the effects of the present invention are superior.

[0053] [5] Method for preparing the 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 apparatus (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 composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[0054] [II] Tires The tires of the present invention are tires manufactured using the compositions of the present invention described above. The tires of the present invention are preferably pneumatic tires and can be filled with air, inert gases such as nitrogen, and other gases.

[0055] Figure 1 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 1.

[0056] In Figure 1, reference numeral 1 represents the bead portion, reference numeral 2 represents the sidewall portion, and reference numeral 3 represents the tire tread portion. Between the pair of left and right bead portions 1, a carcass layer 4 in which fiber cords are embedded is mounted, and the ends of this carcass layer 4 are folded back and wound up from the inside to the outside of the tire around the bead core 5 and bead filler 6. In the tire tread portion 3, a belt layer 7 is arranged around the entire circumference of the tire on the outside of the carcass layer 4. In the bead portion 1, a rim cushion 8 is arranged in the portion that contacts the rim. At least one of reference numerals 2-3, 5-6, and 8 (preferably reference numeral 3) is formed from the composition of the present invention as described above.

[0057] 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.

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] [Preparation of Tire Rubber Composition] The components shown in Tables 1 and 2 below were blended in the proportions (parts by mass) shown in the same tables. Specifically, first, the components excluding sulfur and vulcanization accelerator were kneaded in a 1.7-liter sealed mixer for 5 minutes, and released when the temperature reached 150°C to obtain a masterbatch. Next, sulfur and vulcanization accelerator were kneaded into the obtained masterbatch in an open roll to obtain a tire rubber composition.

[0060] [Wet Grip Performance, Rolling Resistance Performance] The obtained tire rubber composition was vulcanized at 170°C for 15 minutes using a mold of a predetermined shape (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm) to produce a vulcanized rubber sheet. Next, the tanδ of the obtained vulcanized rubber sheet was measured at temperatures of 0°C and 60°C under the conditions of a tensile deformation strain of 10% ± 2% and a vibration frequency of 20 Hz, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K6394:2007. Wet grip performance was evaluated from the tanδ at 0°C, and rolling resistance performance was evaluated from the reciprocal of the tanδ at 60°C. The wet grip performance is shown in Tables 1 and 2 as an index with the value of Comparative Example 1 set to 100. A larger index means better wet grip performance. In practical terms, an index greater than 100 is preferable. Furthermore, the rolling resistance performance is shown in Tables 1 and 2 as an index with the value of Comparative Example 1 set to 100. A larger index indicates better rolling resistance performance (lower rolling resistance). In practical terms, an index greater than 100 is preferable.

[0061]

[0062] In Tables 1 and 2, for resins, the "Mz" column represents the Mz of the resin used in each example, the "Type" column for C9 component represents the type of C9 monomer used in each example, the "Policylicity" column for C9 component represents the polarizability of the C9 monomer used in each example, and the "Polymerization Method" column represents the polymerization method of the resin used in each example (A: anionic polymerization, C: cationic polymerization). The "S1" column represents the S1 of the resin used in each example. The above polarizability values ​​were calculated using Gaussian 16 with a density functional B3LYP method using 3-21G as the basis function.

[0063] [Resins] In Tables 1 and 2, resins 1 to 14 are as follows. Resins 1 to 13 are all polymers of the C9 component, and resin 14 is a polymer of a monomer containing the C9 component. However, resins 1 to 7 do not fall under the category of specified resins as described above because their S1 is less than 18.0, whereas resins 8 to 14 fall under the category of specified resins as described above because their S1 is 18.0 or more.

[0064] <Resin 1> In a polymerization reaction vessel with a stirring device and a volume of 10 L, 4020 g of cyclohexane, 250 mL of styrene (St), and 1.0 mL of 2,2-di(2-tetrahydrofuryl)propane (manufactured by Tokyo Chemical Co., Ltd.) were added and stirred. Next, 100 mL of n-BuLi (n-butyllithium) (manufactured by Kanto Chemical Co., Ltd.: 1.60 mol / L (hexane solution)) was added and stirred at 50°C for 3 hours. After the reaction, 20 mL of methanol was added to stop the polymerization. The obtained solution was taken out and concentrated under reduced pressure. The concentrated solution was poured into methanol (1.0 L) and methanol-insoluble components were separated. As a result, the desired polystyrene (resin 1) (220 g, Mn=1,600, Mw=2,100, Mz=2,900) was obtained in a yield of 97%.

[0065] <Resin 2> Resin (Resin 2) was obtained by the same method as Resin 1, except that the ratio of styrene (St) and n-BuLi was adjusted.

[0066] <Resin 3> 800 mL of dichloromethane, 130 mL of indene (Ind), and 8.0 mL of DMSO were added to a 2 L round-bottom flask and stirred, then the mixture was kept at -40°C. Then TiCl４ 80 mL of (Kanto Chemical Co., Ltd.: 1 mol / L (dichloromethane solution)) was added and the mixture was stirred for 6 minutes. After the reaction, ammoniacal methanol was added to stop the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (1.0 L) to separate the methanol-insoluble components. After redissolving in dichloromethane and washing three times with water, the organic solvent layer was concentrated under reduced pressure. As a result, the desired polyindene (resin 3) (123 g, Mn = 1,000, Mw = 1,800, Mz = 3,300) was obtained in 95% yield.

[0067] <Resin 4> Resin (Resin 4) was obtained in the same manner as Resin 1, except that α-methylstyrene (αMeSt) was used as the monomer and the ratio of the monomer to n-BuLi was adjusted.

[0068] <Resin 5> Resin (Resin 5) was obtained in the same manner as Resin 1, except that p-methylstyrene (pMeSt) was used as the monomer and the ratio of the monomer to n-BuLi was adjusted.

[0069] <Resin 6> Resin (Resin 6) was obtained in the same manner as Resin 1, except that styrene (St) and α-methylstyrene (αMeSt) were used as monomers, and the ratio of monomers to n-BuLi was adjusted.

[0070] <Resin 7> Styrene (St) and α-methylstyrene (αMeSt) are used as monomers, and the monomers and TiCl ４ Aside from adjusting the quantity ratio of the other components, a resin (resin 7) was obtained using the same method as resin 3.

[0071] <Resin 8> Resin (Resin 8) was obtained by the same method as Resin 1, except that α-methylstyrene (αMeSt) was used as the monomer and the ratio of the monomer to n-BuLi was adjusted.

[0072] <Resin 9> Resin (Resin 9) was obtained by the same method as Resin 1, except that p-methylstyrene (pMeSt) was used as the monomer and the ratio of the monomer to n-BuLi was adjusted.

[0073] <Resin 10> Resin (Resin 10) was obtained in the same manner as Resin 1, except that isopropenyltoluene (Ipt) was used as the monomer and the ratio of the monomer to n-BuLi was adjusted.

[0074] <Resin 11> Indene (Ind) and isopropenyltoluene (Ipt) are used as monomers, and the monomers and TiCl ４ Aside from adjusting the quantity ratio of the other components, a resin (resin 11) was obtained using the same method as resin 3.

[0075] <Resin 12> Resin (Resin 12) was obtained by the same method as Resin 1, except that styrene (St) and α-methylstyrene (αMeSt) were used as monomers, and the ratio of monomers to n-BuLi was adjusted.

[0076] <Resin 13> Indene (Ind) and p-methylstyrene (pMeSt) are used as monomers, and the monomers and TiCl ４ Aside from adjusting the quantity ratio of the other components, a resin (resin 13) was obtained using the same method as resin 3.

[0077] <Resin 14> Resin (Resin 14) was obtained in the same manner as Resin 1, except that isoprene and p-methylstyrene (pMeSt) were used as monomers, and the ratio of monomers to n-BuLi was adjusted. The proportion of p-methylstyrene (pMeSt) in the monomers was 50% by mass.

[0078] [Ingredients other than resin] The ingredients other than resin in Tables 1 and 2 are as follows:・SBR: NS612 manufactured by Nippon Zeon (solution polymerized SBR, styrene monomer unit content: 15% by mass, vinyl unit content: 31%, weight-average molecular weight: 440,000, Tg -61℃) ・Silica: ZEOSIL 1165MP manufactured by Solvay ・Carbon black: Seast N manufactured by Tokai Carbon ・Oil: Extract No. 4 S manufactured by Shell Lubricants Japan ・Silane coupling agent: Si69 manufactured by Evonik ・Zinc oxide: Zinc oxide 3 types manufactured by Seido Chemical Industry ・Stearic acid: Bead stearic acid YR manufactured by NOF Corporation ・Anti-aging agent: 6PPD manufactured by Flexis ・Vulcanization accelerator-1: Noxellar CZ-G (CZ) manufactured by Ouchi Shinko Chemical Industry ・Vulcanization accelerator-2: Soxinol D-G (DPG) manufactured by Sumitomo Chemical ・Sulfur: Finely powdered sulfur with Kinka brand oil manufactured by Tsurumi Chemical Industry

[0079] [Summary of Tables 1-2] As can be seen from Tables 1-2, Examples 1-7, which contain the specific resin, showed superior wet grip performance and rolling resistance performance compared to Comparative Examples 1-7, which do not contain the specific resin. In particular, Examples 3-5 and 7, in which the S1 of the specific resin was greater than 25.0, showed even better wet grip performance. Among these, Example 3, in which the S1 of the specific resin was 30.0 or higher, showed even better rolling resistance performance.

[0080] 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. A tire rubber composition comprising 100 parts by mass of a rubber component containing styrene-butadiene rubber, a resin which is a polymer of a monomer containing a C9 component and has the following parameter S1 of 18.0 or higher, and 10 to 300 parts by mass of silica, wherein the content of the resin is 1 to 200% by mass relative to the content of the styrene-butadiene rubber. S1 = (P / 10) ５ / Mz Here, P represents the polarizability of the C9 component, and Mz represents the z-average molecular weight of the resin.

2. The tire rubber composition according to claim 1, wherein the parameter S1 is greater than 25.

0.

3. A tire manufactured using the tire rubber composition described in claim 1 or 2.

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