Rubber composition and its manufacturing method and tire products

Abstract

[Problem] Provision of a rubber composition capable of improving the wear resistance of tires. [Solution] The rubber composition of the present invention comprises a rubber component having a glass transition temperature of -60°C or higher and a rubber additive comprising a sulfur-containing hydrocarbon polymer, wherein the sulfur-containing hydrocarbon polymer is a reaction product of a polymer of unsaturated hydrocarbons and sulfur, wherein the unsaturated hydrocarbons include a cycloaliphatic unsaturated compound, and the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 500 or higher and 4000 or lower.

Description

Technology Field

[0001] The present invention relates to a rubber composition and a method for manufacturing the same. Furthermore, the present invention relates to a tire product manufactured using the rubber composition. Background Technology

[0002] Conventionally, tires have been manufactured from rubber compositions containing a vulcanizing agent responsible for vulcanization, fillers such as carbon black or silica, and anti-aging agents or waxes that suppress quality deterioration, and improvements have been made to each of these components.

[0003] Recently, various performance characteristics, such as wet grip performance and wear resistance, are required for tires. For example, in order to improve the overall performance of wet grip performance and dry grip performance of a tire, a rubber composition has been proposed in which the dynamic elastic modulus (E*) changes reversibly upon contact with water and satisfies a specific formula (dynamic elastic modulus (E*) when wet / dynamic elastic modulus (E*) when dry × 100% ≤ 90%) (see Patent Document 1). However, in the invention described in Patent Document 1, the wear resistance of the tire was not sufficiently examined.

[0004] However, when rubber components with a high glass transition temperature are used in tire rubber compositions to improve wet grip performance, or when additives that raise the glass transition temperature of rubber components, such as petroleum resins, are incorporated, the wear resistance of the tire tends to deteriorate. Therefore, there is a demand for tire rubber compositions that improve tire wear resistance even when rubber components with a high glass transition temperature are used. Prior art literature

[0005] Patent Document 1: International Publication No. 2020 / 022326 means of solving the problem

[0006] Here, the inventors, having diligently examined the above problem, surprisingly discovered that a tire manufactured using a rubber composition obtained by incorporating a rubber additive containing a specific sulfur-containing hydrocarbon polymer into a rubber component with a high glass transition temperature does not deteriorate wear resistance, but rather improves it. Based on this discovery, the inventors have completed the present invention.

[0007] That is, according to the present invention, the following invention is provided.

[0008] [1] Rubber components with a glass transition temperature of -60℃ or higher, and

[0009] Rubber additives containing sulfur-containing hydrocarbon polymers

[0010] Includes,

[0011] The above-mentioned sulfur-containing hydrocarbon polymer is a reaction product between a polymer of unsaturated hydrocarbons and sulfur, and the above-mentioned unsaturated hydrocarbons include alicyclic unsaturated compounds,

[0012] A rubber composition having a weight average molecular weight of the above sulfur-containing hydrocarbon polymer of 500 or more and 4000 or less.

[0013] [2] The rubber composition described in [1], wherein the above-mentioned alicyclic unsaturated hydrocarbon comprises a compound having a norbornene backbone.

[0014] [3] The rubber composition described in [2], which includes the compound having the norbornene backbone, dicyclopentadiene.

[0015] [4] A rubber composition described in [2] or [3] in which unsaturated bonds in the norbornene backbone react with sulfur.

[0016] [5] A rubber composition described in any one of [1] to [4], wherein the glass transition temperature of the rubber component is -50°C or higher and -10°C or lower.

[0017] [6] A rubber composition described in any one of [1] to [5], wherein the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 700 or more and 2000 or less.

[0018] [7] A rubber composition described in any one of [1] to [6], wherein the rubber component is at least one selected from the group consisting of aromatic vinyl-conjugated diene copolymer rubber and conjugated diene (co)polymer rubber.

[0019] [8] A rubber composition described in any one of [1] to [7], wherein the above rubber component comprises at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber.

[0020] [9] A rubber composition described in any one of [1] to [8], further comprising a filler.

[0021]

[10] The rubber composition described in [9] comprises at least one filler selected from the group consisting of silica and carbon black.

[0022]

[11] The content of the above filler is 10 parts by mass or more and less than 200 parts by mass for every 100 parts by mass of the rubber component, as described in [9].

[0023]

[12] A rubber composition described in any one of [1] to

[11] , in which the above rubber additive is a wear resistance enhancer for tires.

[0024]

[13] A rubber composition for tire products, as described in any one of [1] to

[12] .

[0025]

[14] A method for manufacturing a rubber composition comprising at least a process of mixing rubber components and rubber additives,

[0026] The glass transition temperature of the above rubber component is -60℃ or higher, and

[0027] The above rubber additive comprises a sulfur-containing hydrocarbon polymer, and

[0028] The above-mentioned sulfur-containing hydrocarbon polymer is a reaction product between a polymer of unsaturated hydrocarbons and sulfur, and the above-mentioned unsaturated hydrocarbons include alicyclic unsaturated compounds,

[0029] A method for manufacturing a rubber composition having a weight average molecular weight of the above-mentioned sulfur-containing hydrocarbon polymer of 500 or more and 4000 or less.

[0030]

[15] Tire product manufactured using a rubber composition described in any one of [1] to

[13] . Effects of the invention

[0031] According to the present invention, a rubber composition for manufacturing a tire with excellent wear resistance can be provided. Additionally, according to the present invention, a tire with excellent wet grip and steering stability can be manufactured. Specific details for implementing the invention

[0032] [Rubber composition]

[0033] The rubber composition of the present invention comprises a rubber component and a rubber additive, and may additionally include a filler. A tire manufactured using the rubber composition of the present invention exhibits excellent wear resistance, wet grip, and steering stability. The content of the rubber component is preferably 20 mass% or more and 80 mass% or less with respect to the total solid mass of the rubber composition, more preferably 25 mass% or more and 75 mass% or less, and even more preferably 30 mass% or more and 70 mass% or less. The content of the rubber additive is preferably 1 mass part or more and 30 mass parts or less with respect to 100 mass parts of the rubber component, more preferably 3 mass parts or more and 25 mass parts or less, and even more preferably 5 mass parts or more and 20 mass parts or less. The content of the filler is, with respect to 100 parts by mass of the rubber component, preferably 10 parts by mass or more and less than 200 parts by mass, more preferably 15 parts by mass or more and 180 parts by mass or less, even more preferably 20 parts by mass or more and 160 parts by mass or less, even more preferably 30 parts by mass or more and 130 parts by mass or less, and particularly preferably 40 parts by mass or more and 110 parts by mass or less.

[0034] (Rubber component)

[0035] The rubber component used in the rubber composition has a glass transition temperature (Tg) of -60°C or higher, preferably -55°C or higher, more preferably -50°C or higher, and also preferably -10°C or lower, more preferably -15°C or lower, and even more preferably -20°C or lower. In particular, the glass transition temperature (Tg) of the rubber component is preferably -55°C or higher and -10°C or lower, more preferably -50°C or higher and -10°C or lower, even more preferably -50°C or higher and -15°C or lower, and even more preferably -50°C or higher and -20°C or lower. Tires using a rubber component with a glass transition temperature (Tg) within the above numerical range are desirable because they possess good rolling resistance characteristics and excellent wet grip performance, as well as excellent wear resistance. In particular, a tire that uses a rubber component with a glass transition temperature (Tg) within the above numerical range and also contains silica as a filler in a suitable amount (10 parts by mass or more and less than 200 parts by mass per 100 parts by mass of the rubber component) as described below is suitable as an HPT (high performance tire), a fuel-efficient tire, and an all-season tire.

[0036] When using two or more types of rubber as rubber components, the Tg of the rubber components after mixing must be within the above range.

[0037] Additionally, the Tg of the rubber component can be measured by conventionally known methods. For example, the Tg of the rubber component can be measured by differential thermal analysis (DTA) or differential scanning calorimetry (DSC).

[0038] As for the rubber component, it is not particularly limited as long as it satisfies the above Tg, but it is preferable to include diene-based rubber. The following sulfur-containing hydrocarbon polymer has higher reactivity to diene-based rubber and is more likely to react with rubber molecular chains compared to general unsaturated hydrocarbon polymers, such as unsaturated petroleum resins (which do not contain sulfur).

[0039] As for the diene-based rubber, it is preferable to use at least one type of aromatic vinyl-conjugated diene copolymer rubber and conjugated diene (co)polymer rubber. Examples of aromatic vinyl-conjugated diene copolymer rubber include styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber, styrene-isoprene rubber, and styrene-α-methylstyrene-butadiene rubber. Examples of conjugated diene (co)polymer rubber include butadiene rubber (BR), natural rubber (NR), and isoprene rubber (IR). In addition, examples of diene-based rubbers other than these include nitrile rubber (NBR), chloroprene rubber (CR), ethylene-propylene-diene ternary copolymer rubber (EPDM), butyl rubber (IIR), etc., and diene-based rubbers modified from these. Modified diene rubbers include diene rubbers produced by modification methods such as main chain modification, single-end modification, double-end modification, and hydrogenation. Here, various functional groups such as epoxy groups, amino groups, alkoxysilyl groups, and hydroxyl groups may be used as modification functional groups of the modified synthetic diene rubber, and one or more of these functional groups may be included in the modified synthetic diene rubber. Among these, it is preferable to use at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber, more preferable to use at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, and natural rubber, and even more preferable to include at least styrene-butadiene rubber.

[0040] There are no particular limitations on the methods for manufacturing diene rubber, and examples include emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, and cationic polymerization.

[0041] Examples of natural rubber include natural rubber latex, technically standardized rubber (TSR), smoked sheet (RSS), gutta-percha, natural rubber derived from Eucommia ulmoides, natural rubber derived from Guarum citrus, natural rubber derived from Russian dandelion, and fermented rubber derived from plant components. Additionally, modified natural rubbers obtained by modifying these natural rubbers, such as epoxidized natural rubber, methacrylic acid modified natural rubber, styrene modified natural rubber, sulfonic acid modified natural rubber, and zinc sulfonate modified natural rubber, are also included in natural rubber.

[0042] In addition, the ratio of cis / trans / vinyl in the double bond portion of natural rubber and synthetic diene rubber is not particularly limited and can be suitably used at any ratio. In addition, the number average molecular weight and molecular weight distribution of the diene rubber are not particularly limited, but the number average molecular weight is preferably 500 to 3,000,000 and the molecular weight distribution is preferably 1.5 to 15.

[0043] As for the rubber component, non-diene rubber may be incorporated in addition to diene rubber. As for non-diene rubber, known types can be widely used. Specific examples include olefin rubbers such as ethylene-propylene rubber (EPM), chlorosulfonated polyethylene rubber (CSM), acrylic rubber (ACM), urethane rubber (U), silicone rubber (VMQ, PVMQ, FVMQ), fluororubber (FKM), and polysulfide rubber (T).

[0044] In addition, the rubber composition of the present invention may also incorporate an elastomer in addition to the above-mentioned rubber components to the extent that its function is not impaired. Examples of elastomers include thermoplastic elastomers selected from the group consisting of polystyrene-isoprene-styrene ternary block copolymer (SIS), styrene-butadiene-styrene ternary block copolymer (SBS), hydrogenated products thereof (SEBS, SEPS, SEEPS), polyolefin-based elastomers, polyvinyl chloride-based elastomers, polyurethane-based elastomers, polyester-based elastomers, and polyamide-based elastomers.

[0045] The content of diene rubber in the rubber component is preferably 10 mass% or more, more preferably 30 mass% or more, and even more preferably 50 mass% or more, with respect to the total amount of the rubber component. In particular, the total content of aromatic vinyl-conjugated diene copolymer rubber and conjugated diene (co)polymer rubber in the rubber component is preferably 70 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more, with respect to the total amount of the rubber component.

[0046] (Rubber additives)

[0047] The rubber additive used in the rubber composition includes the following sulfur-containing hydrocarbon polymer. When an additive that raises the glass transition temperature of a rubber component, such as a conventionally known petroleum resin, is blended with the above-mentioned rubber component having a high glass transition temperature, the wear resistance of the tire manufactured using the obtained rubber composition deteriorates. On the other hand, in the present invention, by blending a rubber additive containing the following sulfur-containing hydrocarbon polymer with the above-mentioned rubber component having a high glass transition temperature, the wear resistance of the tire manufactured using the obtained rubber composition can be improved. Therefore, the following sulfur-containing hydrocarbon polymer can be used as a wear resistance enhancer for tires.

[0048] (Sulfur-containing hydrocarbon polymer)

[0049] A sulfur-containing hydrocarbon polymer is a reaction product of a polymer of unsaturated hydrocarbons and sulfur. Specifically, it is preferable that the sulfur-containing hydrocarbon polymer is a reaction product obtained by reacting sulfur with the unsaturated bonds of a polymer of unsaturated hydrocarbons.

[0050] The weight average molecular weight (Mw) of the sulfur-containing hydrocarbon polymer is 500 or more and 4000 or less, the lower limit is preferably 600 or more, more preferably 700 or more, and even more preferably 800 or more, and the upper limit is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1500 or less. In particular, the weight average molecular weight (Mw) of the sulfur-containing hydrocarbon polymer is preferably 600 or more and 3000 or less, more preferably 700 or more and 2000 or less, and even more preferably 800 or more and 1500 or less. By reducing the weight average molecular weight of the sulfur-containing hydrocarbon polymer, the bonding of the sulfur-containing hydrocarbon polymers through sulfur is suppressed, and the amount of sulfur bonded to the rubber component is increased, thereby further improving wear resistance, wet grip, and steering stability.

[0051] In addition, the molecular weight distribution (Mw / number average molecular weight (Mn)) of the sulfur-containing hydrocarbon polymer is preferably 1.0 or more and 5.0 or less, more preferably 1.0 or more and 4.0 or less, even more preferably 1.0 or more and 3.0 or less, and even more preferably 1.0 or more and 2.5 or less.

[0052] Additionally, the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) can be measured according to the conventional known method of GPC (gel permeation chromatography) analysis.

[0053] In the present invention, as a raw material for a polymer, at least a hydrocarbon having unsaturated bonds for reacting with sulfur is used. The unsaturated hydrocarbon includes alicyclic unsaturated compounds, and it is preferable that the alicyclic unsaturated hydrocarbon be a compound having a norbornene backbone. This is because the structure of the double bonds of the norbornene backbone is modified and has good reactivity with sulfur. The unsaturated bonds of the alicyclic unsaturated compound may remain after the reaction with sulfur, or they may all be consumed. As for the unsaturated bonds of the alicyclic unsaturated compound, there are unsaturated bonds present in the norbornene backbone and unsaturated bonds present in the cyclopentene backbone; however, from the perspective of improving the wear resistance of the tire, it is more preferable that all unsaturated bonds of the norbornene backbone be consumed.

[0054] In one embodiment of the present invention, as a polymer of unsaturated hydrocarbons, a resin (hereinafter referred to as "petroleum resin") obtained by polymerizing the remaining fraction in a mixed state from which useful compounds such as ethylene, propylene, and butadiene have been removed from the fraction obtained by thermal cracking of naphtha from an industrial manufacturing perspective may be used. Generally, examples of petroleum resins include an aliphatic petroleum resin (C5-based petroleum resin) obtained by (co)polymerizing a C5 fraction, an aromatic petroleum resin (C9-based petroleum resin) obtained by (co)polymerizing a C9 fraction obtained by thermal cracking of naphtha, and a copolymer petroleum resin (C5 / C9-based petroleum resin) obtained by copolymerizing the above C5 fraction and the C9 fraction. In addition, petroleum resin is a transparent, pale yellow to yellowish-brown resin with a molecular weight of 200 to 8000 and a softening point of 5 to 180°C, although the properties of the resin produced vary depending on the olefin content in the raw material.

[0055] In the present invention, a petroleum resin obtained by (co)polymerizing a fraction containing alicyclic unsaturated hydrocarbons among petroleum resins (hereinafter referred to as "alicyclic unsaturated hydrocarbon-based petroleum resin") is used. The alicyclic unsaturated hydrocarbon-based petroleum resin includes, for example, a dimerized cyclopentadienes contained in a C5 fraction to form dicyclopentadienes, separated from other C5 fractions by distillation, and polymerized by heating via a Diels-Alder reaction. Examples of cyclopentadienes include cyclopentadiene, methylcyclopentadiene, etc. Additionally, examples of dicyclopentadienes include dicyclopentadiene (DCPD), methyldicyclopentadiene, etc., and dicyclopentadiene is particularly preferred.

[0056] The alicyclic unsaturated hydrocarbon-based petroleum resin may contain C5 or C9 fractions other than cyclopentadienes.

[0057] Generally, among the fractions obtained by the thermal decomposition of petroleum products, a fraction with a boiling point range of about 20 to 110°C is used as the C5 fraction. Examples of C5 fractions other than cyclopentadienes include olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene.

[0058] Generally, among the fractions obtained by the thermal decomposition of petroleum products, a fraction with a boiling point range of about 100 to 280°C is used as the C9 fraction. Examples of C9 fractions include styrene homologues such as α-methyl styrene, β-methyl styrene, and γ-methyl styrene, and indene homologues such as indene and coumarone.

[0059] The manufacturing method for general C5-based petroleum resins, C9-based petroleum resins, and C5 / C9-based petroleum resins is as follows. A Friedel-Kraft type catalyst is added in an amount of 0.01 to 5 weight percent relative to the raw oil, and a polymerization reaction is carried out. After the reaction is completed, the Friedel-Kraft type catalyst is decomposed and removed using an alkali, and finally, unreacted oil and low-molecular-weight polymers are removed by distillation or the like. Generally, examples of Friedel-Kraft type catalysts include aluminum trichloride, aluminum tribromide, boron trifluoride or its phenolic complex, butanol complex, etc. Among these, a phenolic complex of aluminum trichloride or boron trifluoride, and a butanol complex of boron trifluoride are preferred. The polymerization temperature is preferably 0 to 100 ℃, and particularly preferably 0 to 80 ℃. In addition, the catalyst amount and polymerization time are preferably 0.1 to 10 hours when the catalyst is 0.1 to 2.0 parts by mass per 100 parts by mass of raw oil. The reaction pressure is preferably atmospheric pressure to 1 MPa.

[0060] The petroleum resin may be polymerized with a compound having various functional groups in some parts. Examples of functional groups include alcohol compounds or phenol compounds having hydroxyl groups. Specific examples of alcohol compounds include alcohol compounds having double bonds, such as aryl alcohols and 2-butene-1,4-diol. As phenol compounds, alkyl phenols such as phenol, cresol, xylenol, p-butylphenol, p-octylphenol, and p-nonylphenol may be used. These compounds having hydroxyl groups may be used alone or in combination of two or more.

[0061] In addition, hydroxyl group-containing petroleum resins can also be produced by methods such as thermally polymerizing (meth)acrylate alkyl esters, etc., together with petroleum fractions to introduce ester groups into the petroleum resin and then reducing said ester groups, or by hydrating double bonds remaining or introduced into the petroleum resin. In the present invention, as a hydroxyl group-containing petroleum resin, those obtained by the various methods described above may be used, but from the perspective of performance and manufacturing, it is preferable to use phenol-modified petroleum resins, etc.

[0062] The above phenol-modified petroleum resin is obtained by cationic polymerization of a C9 fraction in the presence of phenol, and is easy to modify.

[0063] The method of polymerization is not particularly limited and can be selected from, for example, a thermal polymerization reaction in which heating is performed at about 1 to 10 hours at about 150 to 300°C, such as the Diels-Alder reaction described above, or the Friedel-Kraft type reaction described above.

[0064] The resins described above preferably have a softening point of 200°C or lower (measurement method: ASTM E 28-58-T), and more preferably 45 to 160°C.

[0065] In the present invention, a partially hydrogenated petroleum resin in which a portion of the double bonds in the above-described petroleum resin is hydrogenated may be used. Although the conditions for hydrogenation are optional, the petroleum resin is mixed with one or more solvents selected from saturated chain hydrocarbons, saturated alicyclic hydrocarbons, and aromatic hydrocarbons having a boiling point of 140 to 280°C at atmospheric pressure, and a general hydrogenation catalyst including nickel, molybdenum, cobalt, palladium, platinum, etc. is used, and the reaction is carried out under conditions of a reaction temperature of 150 to 320°C, a reaction pressure of 3 to 30 MPa, and a reaction time of 1 to 10 hours.

[0066] Commercially available C5, C9, and C5 / C9 petroleum resins having intramolecular double bonds include: Neo Resin EP-140 (softening point: 140°C) manufactured by ENEOS Corporation; Maruka Rez M-890A (softening point: 105°C) manufactured by Maruzen Sekiyu Kagaku Co., Ltd.; Maruka Rez M-845A (softening point: 145°C) manufactured by Maruzen Sekiyu Kagaku Co., Ltd.; T-REZ RB 093 (softening point: 92°C) manufactured by ENEOS Corporation; T-REZ RB 100 (softening point: 98°C) manufactured by ENEOS Corporation; T-REZ RC 093 (softening point: 93°C) manufactured by ENEOS Corporation; T-REZ RC 100 (softening point: 97°C) manufactured by ENEOS Corporation; and T-REZ RC 115 (Softening point: 112℃), ENEOS Corp. T-REZ RD 104 (Softening point: 102℃), ENEOS Corp. T-REZ PR 802 (Softening point: 89℃), Nippon Zeon Corp. Quintone B170 (Softening point: 70℃), Nippon Zeon Corp. Quintone M100 (Softening point: 95℃), Nippon Zeon Corp. Quintone R100 (Softening point: 96℃), Nippon Zeon Corp. Quintone A100 (Softening point: 100℃), Nippon Zeon Corp. Quintone RX110 (Softening point: 110℃), Exxon Mobil Chemical Escorez 1102 (Softening point: 100℃), Exxon Mobil Chemical Escorez 1304 (Softening point: Examples include Exxon Mobil Chemical’s Escorez 1310LC (softening point: 100℃), Exxon Mobil Chemical’s Escorez 1315 (softening point: 115℃), KOLON Indutries’ HIKOREZ A-1100 (softening point: 98℃), KOLON Indutries’ HIKOREZ A-1115 (softening point: 112℃), KOLON Indutries’ HIKOREZ A-2115 (softening point: 112℃), KOLON Indutries’ HIKOREZ C-1100 (softening point: 98℃), etc.

[0067] (Method for manufacturing sulfur-containing hydrocarbon polymers)

[0068] A sulfur-containing hydrocarbon polymer can be prepared by reacting an unsaturated hydrocarbon with sulfur in a molten state while heating it in a solvent-free environment. By performing the heating reaction in a solvent-free environment rather than in a solvent, the weight-average molecular weight of the sulfur-containing hydrocarbon polymer can be reduced, and the variation in molecular weight can be reduced. Additionally, the conditions of the heating reaction are not particularly limited and can be appropriately set, but preferably at 90 to 160°C, more preferably at 100 to 150°C, and even more preferably at 100 to 140°C, and the reaction time is preferably 0.5 to 10 hours, and more preferably 1 to 8 hours. Furthermore, the weight-average molecular weight of the sulfur-containing hydrocarbon polymer can be controlled by adjusting the conditions of the heating reaction.

[0069] According to the above manufacturing method, since side reactions can be suppressed, the yield of the sulfur-containing hydrocarbon polymer is improved, so it can be incorporated directly into a rubber composition without undergoing a purification process.

[0070] The amount of sulfur added to the petroleum resin is not particularly limited, but it is preferable to have a ratio of 0.1 equivalent or more, preferably 0.3 to 5 equivalents, per unsaturated bond (double bond) of the unsaturated hydrocarbon.

[0071] In the present invention, it is preferable to use a compound having a norbornene skeleton, particularly dicyclopentadiene, as an unsaturated alicyclic hydrocarbon. Additionally, it is preferable that the double bonds on the norbornene skeleton of dicyclopentadiene react with sulfur, and it is more preferable that only the double bonds on the norbornene skeleton react with sulfur. The double bonds on the norbornene skeleton that are consumed by reacting with sulfur are 1 It can be confirmed by H-NMR.

[0072] (Filling)

[0073] Examples of fillers include silica, carbon black, and barium sulfate, and it is preferable to use at least one of silica and carbon black, and it is more preferable to use silica.

[0074] (Silica)

[0075] Silica is not particularly limited, but examples include dry-process silica, wet-process silica, colloidal silica, and precipitated silica. Among these, wet-process silica with hydrated silica as the main component is preferred. These silicas can be used individually or in combination of two or more types.

[0076] The specific surface area of ​​silica is not particularly limited, but is typically 10 to 400 m² as the nitrogen adsorption specific surface area (BET method). 2 / g, preferably 20~300 m 2 / g, more preferably 120~190 m 2 The range is / g. If the specific surface area of ​​silica is within the above numerical range, mechanical properties, etc. can be improved. Here, the nitrogen adsorption specific surface area is a value measured by the BET method in accordance with ASTM D 3037-81.

[0077] (Silanic coupling agent)

[0078] When incorporating silica, it is preferable to incorporate a silane coupling agent. Known silane coupling agents may be used as silane coupling agents. Examples include bis[3-(triethoxysilyl)propyl]tetrasulfide, bis[3-(triethoxysilyl)propyl]disulfide, 3-octanoylthio-1-propyltriethoxysilane, and their homocondensates or cocondensates with 3-mercaptopropyltriethoxysilane. For bis[3-(triethoxysilyl)propyl]tetrasulfide, commercially available products may be used, and for example, Si-69 manufactured by Evonik Co., Ltd. In addition, regarding bis[3-(triethoxysilyl)propyl]disulfide, commercially available products may be used, for example, Si-75 manufactured by Evonik. In addition, 3-octanoylthio-1-propyltriethoxysilane may be used, for example, NXT-silane manufactured by Momentive. In addition, commercially available condensates of 3-octanoylthio-1-propyltriethoxysilane may be used, for example, NXT-Z45 silane manufactured by Momentive. The content of the silane coupling agent is preferably 1 to 20 mass% of the silica content, and more preferably 2 to 10 mass%.

[0079] (Other processed preparations)

[0080] The rubber composition of the present invention may include other processing aids, such as vulcanizing agents, vulcanization accelerators, vulcanization accelerating aids, anti-aging agents, softeners, antioxidants, and coloring agents, to the extent that its function is not impaired.

[0081] Examples of vulcanizing agents include sulfur-based vulcanizing agents such as powdered sulfur, precipitated sulfur, highly dispersed sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, and alkylphenol disulfide, or zinc oxide, magnesium oxide, lysage, p-quinone dioxime, p-dibenzoylquinone dioxime, tetrachloro-p-benzoquinone, poly-p-dinitrobenzene, methylenedianiline, phenol resin, alkyl phenol bromide resin, and alkyl phenol chloride resin. The content of the vulcanizing agent is preferably 0.1 to 10 parts by mass and more preferably 1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0082] Examples of vulcanization accelerators include thiuram-based agents such as tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), and tetramethylthiuram monosulfide (TMTM); aldehyde-ammonia-based agents such as hexamethylenetetramine; guanidine-based agents such as diphenylguanidine (DPG); thiazole-based agents such as 2-mercaptobenzothiazole (MBT) and dibenzothiazyl disulfide (DM); sulfenamide-based agents such as N-cyclohexyl-2-benzothiazyl sulfenamide (CBS) and Nt-butyl-2-benzothiazyl sulfenamide (BBS); and dithiocarbamate salt-based agents such as zinc dimethyldithiocarbamate (ZnPDC). The content of the vulcanization accelerator is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0083] Examples of vulcanization accelerating agents include fatty acids such as acetic acid, propionic acid, butyric acid, stearic acid, acrylic acid, and maleic acid; zinc fatty acids such as zinc acetate, zinc propionate, zinc butyrate, zinc stearate, zinc acrylate, and zinc maleate; zinc fatty acid salts, which are salts thereof; and zinc oxide. The content of the vulcanization accelerating agent is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0084] Examples of anti-aging agents include compounds such as aliphatic and aromatic hindered amines and hindered phenols. The content of the anti-aging agent is preferably 0.1 to 10 parts by mass and more preferably 1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0085] Examples of antioxidants include butyl hydroxytoluene (BHT) and butyl hydroxyanisole (BHA). The content of the antioxidant is preferably 0.1 to 10 parts by mass and more preferably 1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0086] As for the softening agent, conventionally known ones may be used and are not particularly limited, examples include petroleum-based softening agents such as aroma oil, paraffin oil, and naphthenic oil, or plant-based softening agents such as palm oil, castor oil, cottonseed oil, and soybean oil. When using, one type alone or two or more types may be appropriately selected and used from among these. When containing a softening agent, from the perspective of ease of handling, among the softening agents described above, it is preferable to contain a petroleum-based softening agent that is liquid at room temperature, such as 25°C, for example, aroma oil, paraffin oil, and naphthenic oil, and aroma oil is particularly preferred. The content of the softening agent is preferably 10 to 200 parts by mass, and more preferably 20 to 100 parts by mass, per 100 parts by mass of the rubber component.

[0087] Examples of coloring agents include inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, Bengala, Lithon, lead, cadmium, iron, cobalt, aluminum, hydrochloric acid salts, sulfate salts, azo pigments, and copper phthalocyanine pigments. The content of the coloring agent is preferably 0.1 to 10 parts by mass and more preferably 1 to 5 parts by mass per 100 parts by mass of the rubber component.

[0088] Other processing aids can be used as a rubber composition by mixing with rubber components using known rubber mixers, such as rollers, Banbury mixers, or kneaders, and vulcanizing under any conditions. The amount of other processing aids added can be the conventional general content, provided that it does not contradict the purpose of the present invention.

[0089] [Method for manufacturing a rubber composition]

[0090] The method for manufacturing a rubber composition of the present invention comprises at least a process of kneading the above-mentioned rubber component and the above-mentioned rubber additive. Preferably, the method for manufacturing a rubber composition may further comprise a process of kneading the above-mentioned vulcanizing agent. More preferably, it may further comprise a process of kneading the above-mentioned vulcanizing agent and the above-mentioned vulcanization accelerator.

[0091] In addition, the method for manufacturing the rubber composition may appropriately incorporate and knead the above-mentioned other processing aids to the extent that the function of the rubber composition is not impaired.

[0092] In manufacturing a rubber composition, a conventionally known mixing device may be used, and the mixing temperature, time, and mixing order may be appropriately selected.

[0093] [Tire Products]

[0094] Tire products can be manufactured using the rubber composition of the present invention and conventional methods and technical common sense widely known to those skilled in the art. Examples of tire products include tires and other related components. For instance, a tire can be manufactured by extruding the rubber composition, then molding it using a tire molding machine, and subsequently forming crosslinks by heating and pressurizing it using a vulcanizer. Tires manufactured using the rubber composition of the present invention exhibit excellent wear resistance, wet grip, and steering stability.

[0095] There are no particular restrictions on the applications of the tire; examples include passenger car tires, heavy-duty tires, motorcycle tires, and studless tires. Among these, it is suitable for use as a passenger car tire. In particular, it is suitable for use as an HPT (High Performance Tire), fuel-efficient tire, and all-season tire.

[0096] There are no particular restrictions on the shape, structure, size, and material of the tire, and they can be appropriately selected according to the purpose. Furthermore, the rubber composition of the present invention can be applied to various parts of the tire. There are no particular restrictions on the parts of the tire to which it is applied, and the tread, carcass, sidewall, inner liner, undertread, belt section, etc., can be appropriately selected according to the purpose.

[0097] [Rubber Products]

[0098] Rubber products other than tire products may be manufactured using the rubber composition of the present invention. Examples of rubber products other than tires include rubber parts for automobiles (exterior, interior, weather strips, boots, mounts, seals, sealers, gaskets), hoses, belts, seats, anti-vibration rubber, rollers, linings, rubber inserts, sealing materials, gloves, anti-vibration parts, medical rubber (syringe gaskets, tubes, catheters), gaskets (for home appliances, construction), asphalt modifiers, grips, toys, shoes, sandals, keypads, gears, PET bottle cap liners, etc.

[0099] [Example]

[0100] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0101] (Preparation Example 1)

[0102] · Synthesis of sulfur-containing hydrocarbon polymer A

[0103] 90 g of petroleum resin A (Mw: 810, Mw / Mn: 1.74, softening point 85°C, iodine value (according to JIS K0070): 185.0, polymer of unsaturated hydrocarbons containing DCPD) was placed in a 300 ml two-necked flask and heated to 130°C to a molten state. Next, 8.7 g of sulfur was added to the flask and stirred for 3 hours. After the reaction was complete, the reaction product was poured into an aluminum dish and allowed to cool naturally.

[0104] After that, the obtained reactant 1 H-NMR analysis was performed to confirm the consumption of double bonds on the norbornene skeleton at around 5.8 ppm. Additionally, GPC analysis of the reactants revealed Mw: 1,220 and Mw / Mn: 2.10. Elemental analysis showed a sulfur content of 8.9 mass%, confirming the introduction of 3.01 sulfur molecules per double bond on the norbornene skeleton.

[0105] (Preparation Example 2)

[0106] Synthesis of sulfur-containing hydrocarbon polymer B

[0107] In the synthesis of the above-mentioned sulfur-containing hydrocarbon polymer A, the reaction was carried out in the same manner except that the heating temperature was changed to 120°C and the stirring time was changed to 1 hour.

[0108] After that, the obtained reactant 1 H-NMR analysis was performed to confirm the consumption of double bonds on the norbornene skeleton at around 5.8 ppm. In addition, GPC analysis of the reactants showed Mw: 816 and Mw / Mn: 1.73. From elemental analysis, the sulfur content was 9.0 mass%, confirming the introduction of 3.04 sulfur molecules per double bond on the norbornene skeleton.

[0109] (Preparation Example 3)

[0110] Synthesis of sulfur-containing hydrocarbon polymer C

[0111] In the synthesis of the above-mentioned sulfur-containing hydrocarbon polymer A, the reaction was carried out in the same manner except that the heating temperature was changed to 120°C and the stirring time was changed to 6 hours.

[0112] After that, the obtained reactant 1 H-NMR analysis was performed to confirm the consumption of double bonds on the norbornene skeleton at around 5.8 ppm. In addition, GPC analysis of the reactants showed Mw: 1,011 and Mw / Mn: 1.90. From elemental analysis, the sulfur content was 8.9 mass%, confirming the introduction of 3.01 sulfur molecules per double bond on the norbornene skeleton.

[0113] (Jojeye 4)

[0114] Synthesis of sulfur-containing hydrocarbon polymer D

[0115] In the synthesis of the above-mentioned sulfur-containing hydrocarbon polymer A, the reaction was carried out in the same manner except that the stirring time was changed to 5 hours.

[0116] After that, the obtained reactant 1 H-NMR analysis was performed to confirm the consumption of double bonds on the norbornene skeleton at around 5.8 ppm. In addition, GPC analysis of the reactants showed Mw: 1,458 and Mw / Mn: 2.32. From elemental analysis, the sulfur content was 8.9 mass%, confirming the introduction of 3.01 sulfur molecules per double bond on the norbornene skeleton.

[0117] (Preparation Example 5)

[0118] · Synthesis of hydrocarbon polymer E

[0119] C5 fractions and C9 fractions obtained from a naphtha cracker were used as raw material monomers, and subjected to a polymerization process using an acid catalyst, a neutralization process of residual catalyst, and a removal process of light fractions to obtain a petroleum resin with an aromatic fraction of 12%, a softening point of 90°C, and an Mw of 1300.

[0120] [Example 1]

[0121] Each of the following components was kneaded using a 250 mL kneader (Laboplast Mill manufactured by Toyo Seiki Co., Ltd.) to obtain a rubber composition. The details of the kneading operation performed are as described in (i) to (iii) below.

[0122] (i) Mixer kneading: Rubber components were introduced into a closed pressure kneader heated to 130°C and kneaded at 30 rpm for 1 minute. Then, half of the mixture of silica, zinc oxide, stearic acid, and anti-aging agent was weighed and taken, along with the entire amount of silane coupling agent 1 and the entire amount of sulfur-containing hydrocarbon polymer A. The rotation speed was increased to 50 rpm and kneading was performed for 1 minute and 30 seconds. Additionally, the remaining half of the mixture of silica, zinc oxide, stearic acid, and anti-aging agent was added, kneading was performed for 5 minutes and 30 seconds, and the mixture was discharged.

[0123] (ii) Rimill: In order to improve the dispersion of silica, the mixture was discharged into a closed-type pressurized kneader heated to 120°C and cooled sufficiently, then further kneaded at 50 rpm for 2 minutes, and discharged.

[0124] (iii) Roll mixing (addition of vulcanizing agent): After releasing and the temperature has sufficiently dropped, sulfur, a vulcanizing accelerator, etc. are added to the mixture described above using two rolls and mixed to obtain a rubber composition.

[0125] · Rubber (SBR(A), Tg: -27℃) 100 parts by mass

[0126] · Silica AQ (Manufactured by Tosos, Product Name: Nifseal AQ) 70 parts by mass

[0127] · Zinc Oxide No. 3 (Manufactured by Tohoaen, Trade Name: Silver Ring R) 3 parts by mass

[0128] · 1 part by mass of stearic acid (Shin Nihon Rika, trade name: Stearic Acid 300)

[0129] · Anti-aging agent (Manufactured by Ouchi Shinko Kagaku Co., Ltd., Product name: Knocklock 6C) 1 part by mass

[0130] · Silane coupling agent 1 (Manufactured by Evonik, Trade name: Si69) 5.6 parts by mass

[0131] · 15 parts by mass of sulfur-containing hydrocarbon polymer A

[0132] · Sulfur (Hosoikagaku Co., Ltd., 5% oil-treated sulfur) 1 part by mass

[0133] · Vulcanization accelerator (Manufactured by Ouchi Shinko Kagaku Co., Ltd., Product name: Knockceller-CZ) 2.3 parts by mass

[0134] · Vulcanization accelerator (Manufactured by Ouchi Shinko Kagaku Co., Ltd., Product name: Knockceller-D) 1 part by mass

[0135] [Comparative Example 1]

[0136] A rubber composition was obtained by adding 15 parts by mass of hydrocarbon polymer E (sulfur-free) instead of sulfur-containing hydrocarbon polymer A, and changing the amount of sulfur added to 1.5 parts by mass, in the same manner as in Example 1.

[0137] [Example 2]

[0138] A rubber composition was obtained in the same manner as in Example 1, except that 5.6 parts by mass of silane coupling agent 2 (manufactured by Evonik, trade name: Si-75) was added instead of silane coupling agent 1 (Si69).

[0139] [Example 3]

[0140] A rubber composition was obtained in the same manner as in Example 1, except that 5.6 parts by mass of silane coupling agent 3 (manufactured by Evonik, trade name: Si-363) was added instead of silane coupling agent 1 (Si69).

[0141] [Example 4]

[0142] A rubber composition was obtained in the same manner as in Example 1, except that 5.6 parts by mass of silane coupling agent 4 (Momentive, trade name: NXT-silane) was added instead of silane coupling agent 1 (Si69).

[0143] [Example 5]

[0144] A rubber composition was obtained in the same manner as in Example 1, except that 5.6 parts by mass of silane coupling agent 5 (Momentive, trade name: NXT-Z45 silane) was added instead of silane coupling agent 1 (Si69).

[0145] [Example 6]

[0146] A rubber composition was obtained by making it the same as in Example 1, except that the amount of silica added was changed to 40 parts by mass.

[0147] [Comparative Example 2]

[0148] A rubber composition was obtained in the same manner as in Example 6, except that 15 parts by mass of hydrocarbon polymer E were added instead of sulfur-containing hydrocarbon polymer A, and the amount of sulfur added was changed to 1.5 parts by mass.

[0149] [Example 7]

[0150] A rubber composition was obtained by making it the same as Example 1, except that the amount of silica added was changed to 150 parts by mass.

[0151] [Comparative Example 3]

[0152] A rubber composition was obtained in the same manner as in Example 7, except that 15 parts by mass of hydrocarbon polymer E were added instead of sulfur-containing hydrocarbon polymer A, and the amount of sulfur added was changed to 1.5 parts by mass.

[0153] [Example 8]

[0154] A rubber composition was obtained by changing the amount of SBR(A)(Tg: -27℃) added as a rubber component to 70 parts by mass and adding 30 parts by mass of BR(Tg: -100℃), in the same manner as in Example 1.

[0155] [Comparative Example 4]

[0156] A rubber composition was obtained in the same manner as in Example 8, except that 15 parts by mass of hydrocarbon polymer E were added instead of sulfur-containing hydrocarbon polymer A, and the amount of sulfur added was changed to 1.5 parts by mass.

[0157] [Example 9]

[0158] A rubber composition was obtained by changing the amount of SBR(A)(Tg: -27℃) added as a rubber component to 60 parts by mass, and adding 20 parts by mass of BR(Tg: -100℃) and 20 parts by mass of NR(Tg: -79℃), in the same manner as in Example 1.

[0159] [Comparative Example 5]

[0160] A rubber composition was obtained in the same manner as in Example 9, except that 15 parts by mass of hydrocarbon polymer E were added instead of sulfur-containing hydrocarbon polymer A, and the amount of sulfur added was changed to 1.5 parts by mass.

[0161] [Example 10]

[0162] A rubber composition was obtained by changing the amount of SBR(A)(Tg: -27℃) added as a rubber component to 60 parts by mass and adding 40 parts by mass of BR(Tg: -100℃), except for the addition of 40 parts by mass of BR(Tg: -100℃), as in Example 1.

[0163] [Comparative Example 6]

[0164] A rubber composition was obtained by adding 15 parts by mass of hydrocarbon polymer E instead of sulfur-containing hydrocarbon polymer A, and changing the amount of sulfur added to 1.5 parts by mass, in the same manner as in Example 10.

[0165] [Comparative Example 7]

[0166] A rubber composition was obtained in the same manner as Comparative Example 1, except that 100 parts by mass of SBR(B)(Tg: -64℃) was added instead of SBR(A) as a rubber component.

[0167] [Comparative Example 8]

[0168] A rubber composition was obtained by adding 15 parts by mass of sulfur-containing hydrocarbon polymer A instead of hydrocarbon polymer E, and changing the amount of sulfur added to 1 part by mass, in the same manner as Comparative Example 7.

[0169] [Comparative Example 9]

[0170] A rubber composition was obtained in the same manner as Comparative Example 1, except that 100 parts by mass of NR (Tg: -79℃) was added instead of SBR (A) as a rubber component, the amount of sulfur added was changed to 2.5 parts by mass, the amount of vulcanization accelerator (Knockceller-CZ) added was changed to 2 parts by mass, and the amount of vulcanization accelerator (Knockceller-D) added was changed to 1.5 parts by mass.

[0171] [Comparative Example 10]

[0172] A rubber composition was obtained in the same manner as Comparative Example 9, except that 15 parts by mass of sulfur-containing hydrocarbon polymer A were added instead of hydrocarbon polymer E, and the amount of sulfur added was changed to 2 parts by mass.

[0173] [Physical Property Evaluation]

[0174] The rubber compositions obtained in Examples 1 to 10 and Comparative Examples 1 to 10 were used, and the following measurements were performed. Additionally, the Tg of each rubber component was measured using a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science, Product No.: DSC7000X) under the conditions of sample amount: about 10 mg, flow conditions: nitrogen gas 40 ml / min, and heating rate: 20℃ / min.

[0175] (tensile strength)

[0176] 42 g of each rubber composition was placed into a mold (150 mm x 150 mm x 1 mm), heated and pressed for 40 minutes under conditions of 160°C and 20 MPa, and a 1 mm thick rubber sheet (thickness 1 mm, length 150 mm, width 150 mm) was obtained. A No. 3 dumbbell-shaped test specimen was punched from each rubber sheet, and a tensile test at a tensile speed of 500 mm / min was performed in accordance with JIS K6251 (published in 2010), and the 100% modulus [MPa] was measured at room temperature (25°C). In addition, in each example and each comparative example, the value of the 100% modulus, which is an indicator of the crosslinking density of each rubber sheet, was adjusted to be approximately the same value, and then other physical properties were confirmed.

[0177] (Wear amount)

[0178] 15 g of each rubber composition was molded into a disc-shaped sample with a diameter of 16.0 mm and a thickness of 8 mm. Next, each of the obtained disc-shaped samples was used to perform an abrasion resistance test in accordance with JIS K6264-2 (published in 2005) using a DIN abrasion tester (rotary cylindrical abrasion tester: product name "DIN Abrasion Tester" manufactured by Yasuda Seiki Co., Ltd.) under the conditions of temperature: room temperature (25℃), load: 2.5 N, drum rotation speed: 40 rpm, and sample lateral feed speed: 2.8 mm / sec, and the amount of wear (volume basis: ratio of the volume worn by the test to the total volume before wear (volume %)) was measured. Additionally, a small amount of wear indicates excellent abrasion resistance.

[0179] (hardness)

[0180] For each rubber sheet obtained above, the rubber hardness of Type A according to ISO standards at a temperature of 25°C was measured using a durometer (manufactured by Toyo Seiki Seisakusho Co., Ltd., Product No.: GS-610) in accordance with JIS K 6253. A higher hardness value indicates a harder material. Additionally, in each example and each comparative example, the hardness of each rubber sheet was adjusted to be approximately the same value, and then other physical properties were verified.

[0181] (Wet grip)

[0182] For each rubber sheet obtained above, tanδ at a measurement temperature of 0°C was measured using a viscoelasticity measuring device (REOGEL E-4000 manufactured by UBM) in accordance with JIS K 6394, under conditions of a deformation of about 0.1% and a frequency of 10 Hz in tensile mode. A high value of tanδ (0°C) indicates excellent wet grip.

[0183] (Elasticity modulus)

[0184] For each rubber sheet obtained above, E' (30°C) was measured in tensile mode at a temperature of 30°C under conditions of deformation of about 0.1%, frequency of 10 Hz, and a viscoelasticity measuring device (REOGEL E-4000 manufactured by UBM) in accordance with JIS K 6394: 2007. A high value of E' (30°C) indicates excellent steering stability.

[0185] The above measurement results are shown in Tables 1 and 2. Additionally, regarding the respective results for wear resistance, wet grip, and steering stability, Examples 1 to 5 are described as relative values ​​when each value in Comparative Example 1 is set to 100, Example 6 is described as a relative value when each value in Comparative Example 2 is set to 100, Example 7 is described as a relative value when each value in Comparative Example 3 is set to 100, Example 8 is described as a relative value when each value in Comparative Example 4 is set to 100, Example 9 is described as a relative value when each value in Comparative Example 5 is set to 100, Example 10 is described as a relative value when each value in Comparative Example 6 is set to 100, Comparative Example 8 is described as a relative value when each value in Comparative Example 7 is set to 100, and Comparative Example 10 is when each value in Comparative Example 9 is set to 100 It was written as a relative value for the case.

[0186]

[0187]

[0188] From the results of Examples 1 to 5 and Comparative Example 1, the results of Example 6 and Comparative Example 2, and the results of Example 7 and Comparative Example 3, the rubber sheet obtained by adding sulfur-containing hydrocarbon polymer A instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -27°C had excellent wear resistance, wet grip, and steering stability.

[0189] From the results of Example 8 and Comparative Example 4, the rubber sheet obtained by adding sulfur-containing hydrocarbon polymer A instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -49°C had excellent wear resistance, wet grip, and steering stability.

[0190] From the results of Example 9 and Comparative Example 5, the rubber sheet obtained by adding sulfur-containing hydrocarbon polymer A instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -50°C had excellent wear resistance, wet grip, and steering stability.

[0191] From the results of Example 10 and Comparative Example 6, the rubber sheet obtained by adding sulfur-containing hydrocarbon polymer A instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -56°C had excellent wear resistance, wet grip, and steering stability.

[0192] From the results of Comparative Examples 7 and 8, sulfur-containing hydrocarbon polymer A was added instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -64°C, but the resulting rubber sheet did not show improved wear resistance, wet grip, and steering stability.

[0193] From the results of Comparative Examples 9 and 10, sulfur-containing hydrocarbon polymer A was added instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -70°C, but the resulting rubber sheet did not show improved wear resistance, wet grip, and steering stability.

[0194] Accordingly, it has been found that by using the rubber composition of the present invention, it is possible to manufacture a tire with excellent wear resistance, wet grip, and steering stability.

[0195] (Example 11)

[0196] A rubber composition was obtained in the same manner as in Example 8, except that 15 parts by mass of sulfur-containing hydrocarbon polymer B were added instead of sulfur-containing hydrocarbon polymer A.

[0197] (Example 12)

[0198] A rubber composition was obtained in the same manner as in Example 8, except that 15 parts by mass of sulfur-containing hydrocarbon polymer C were added instead of sulfur-containing hydrocarbon polymer A.

[0199] (Example 13)

[0200] A rubber composition was obtained in the same manner as in Example 8, except that 15 parts by mass of sulfur-containing hydrocarbon polymer D were added instead of sulfur-containing hydrocarbon polymer A.

[0201] [Physical Property Evaluation]

[0202] The rubber compositions obtained in Examples 11 to 13 were used, and tensile strength and wear amount measurements were performed in the same manner as above. The measurement results are shown in Table 3. Additionally, regarding the results for wear resistance, wet grip, and steering stability, Examples 11 to 13 were described as relative values ​​when each value in Comparative Example 4 was set to 100.

[0203] From the results of Examples 11 to 13 and Comparative Example 4, the rubber sheet obtained by adding sulfur-containing hydrocarbon polymers B to D instead of sulfur-containing hydrocarbon polymer E to a rubber component with a glass transition temperature of -49°C had excellent wear resistance, wet grip, and steering stability.

[0204]

Claims

Claim 1 A rubber composition comprising a rubber component having a glass transition temperature of -50°C or higher and -10°C or lower as measured by differential scanning calorimetry, and a rubber additive comprising a sulfur-containing hydrocarbon polymer, wherein the sulfur-containing hydrocarbon polymer is a reaction product of a polymer of unsaturated hydrocarbons and sulfur, wherein the unsaturated hydrocarbons include alicyclic unsaturated compounds, and the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 500 or higher and 4000 or lower. Claim 2 A rubber composition according to claim 1, wherein the alicyclic unsaturated hydrocarbon comprises a compound having a norbornene backbone. Claim 3 A rubber composition according to claim 2, wherein the compound having the norbornene backbone comprises dicyclopentadiene. Claim 4 A rubber composition according to claim 2, wherein the unsaturated bonds in the norbornene backbone are formed by reacting with sulfur. Claim 5 A rubber composition according to claim 1, wherein the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 500 or more and 1500 or less. Claim 6 A rubber composition according to claim 1, wherein the rubber component comprises at least one selected from the group consisting of aromatic vinyl-conjugated diene copolymer rubber and conjugated diene (co)polymer rubber. Claim 7 A rubber composition according to claim 1, wherein the rubber component comprises at least one selected from the group consisting of styrene-butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber. Claim 8 A rubber composition according to claim 1, further comprising a filler. Claim 9 A rubber composition according to claim 8, wherein the filler comprises at least one selected from the group consisting of silica and carbon black. Claim 10 A rubber composition according to claim 8, wherein the content of the filler is 10 parts by mass or more and less than 200 parts by mass with respect to 100 parts by mass of the rubber component. Claim 11 A rubber composition according to any one of claims 1 to 10, wherein the rubber additive is a wear resistance enhancer for a tire. Claim 12 A rubber composition for a tire product, according to any one of claims 1 to 10. Claim 13 A method for manufacturing a rubber composition comprising a process of mixing at least a rubber component and a rubber additive, wherein the glass transition temperature of the rubber component measured by differential scanning calorimetry is -50°C or higher and -10°C or lower, the rubber additive comprises a sulfur-containing hydrocarbon polymer, the sulfur-containing hydrocarbon polymer is a reaction product of a polymer of unsaturated hydrocarbons and sulfur, the unsaturated hydrocarbon comprises an alicyclic unsaturated compound, and the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 500 or higher and 4000 or lower. Claim 14 A method for manufacturing a rubber composition according to claim 13, wherein the weight average molecular weight of the sulfur-containing hydrocarbon polymer is 500 or more and 1500 or less. Claim 15 A tire product manufactured using the rubber composition of any one of claims 1 to 10.

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