Rubber composition for tire case member, tire case member, and tire

Abstract

To provide a rubber composition for a tire case member, capable of improving the ratio of sustainable materials of a tire while maintaining productivity and performance of the tire, and to provide a tire case member to which the rubber composition is applied.SOLUTION: The rubber composition for a tire case member contains a rubber component (A) and at least one resin component (B) selected from the group consisting of terpene-based resins and rosin-based resins. The tire case member contains the rubber composition for a tire case member.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition for a tire case member, a tire case member, and a tire.

Background Art

[0002] Generally, in a rubber composition for a tire case member, a resin component such as a petroleum resin is blended in order to improve tack (adhesiveness) and make it easier to adhere to an adjacent member, thereby improving workability in the molding of a green tire. However, when a rubber composition containing a large amount of a resin component such as a petroleum resin is applied to a tire case member, the case rigidity of the tire tends to decrease, and tack (adhesiveness) and case rigidity are in an antinomic relationship.

[0003] On the other hand, recently, from the viewpoint of social sustainability, various members used in tires are also required to use so-called sustainable materials such as materials derived from biomass resources and materials derived from recycled resources. For the above-mentioned rubber composition for a tire case member, an improvement in the ratio of sustainable materials is also required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to increase the proportion of sustainable materials in tires, simply replacing the currently used materials derived from fossil resources with sustainable materials in the rubber composition for tire case members results in insufficient tack (adhesiveness) as described above, deteriorates the workability in the molding of green tires, reduces the productivity of tires, or may reduce the case rigidity of tires and thus degrade the tire performance.

[0006] Therefore, an object of the present invention is to provide a rubber composition for a tire case member and a tire case member applying such a rubber composition, which can improve the proportion of sustainable materials in a tire while maintaining the productivity and performance of the tire. Another object of the present invention is to provide a tire with an improved proportion of sustainable materials while maintaining productivity and performance.

Means for Solving the Problems

[0007] The gist of the rubber composition for a tire case member, the tire case member, and the tire of the present invention for solving the above problems is as follows.

[0008] [1] A rubber composition for a tire case member, comprising a rubber component (A) and at least one resin component (B) selected from the group consisting of terpene resins and rosin resins. The rubber composition for a tire case member of the present invention described in [1] above can improve the proportion of sustainable materials in a tire while maintaining the productivity and performance of the tire. The rubber composition for a tire case member of the present invention described in [1] above can improve the productivity and performance of the tire.

[0009] [2] The rubber composition for a tire case member according to [1], wherein the content of the resin component (B) is 0.5 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). The rubber composition for a tire case member described in [2] above can improve the productivity and performance of the tire.

[0010] [3] The rubber composition for a tire case member according to [1] or [2], wherein the rubber component (A) contains an isoprene skeleton rubber. The rubber composition for a tire case member according to the above [3] can increase the breaking strength of the tire case member.

[0011] [4] The resin component (B) has a difference in SP value from the isoprene skeleton rubber of 0.6 (cal / cm 3 ) 1 / 2 The rubber composition for a tire case member according to [3], which is as follows. The rubber composition for a tire case member according to the above [4] is excellent in fracture resistance.

[0012] [5] A tire case member, comprising the rubber composition for a tire case member according to any one of [1] to [4]. The tire case member of the present invention according to the above [5] can improve the ratio of sustainable materials of the tire while maintaining the productivity and performance of the tire.

[0013] [6] A tire, comprising the tire case member according to [5]. The tire of the present invention according to the above [6] has an improved ratio of sustainable materials while maintaining productivity and performance.

Effect of the Invention

[0014] According to the present invention, it is possible to provide a rubber composition for a tire case member capable of improving the ratio of sustainable materials of the tire while maintaining the productivity and performance of the tire, and a tire case member to which such a rubber composition is applied. Further, according to the present invention, it is possible to provide a tire having an improved ratio of sustainable materials while maintaining productivity and performance.

Brief Description of the Drawings

[0015]

Figure 1

Mode for Carrying Out the Invention

[0016] Hereinafter, the rubber composition for the case member of the tire of the present invention, the case member of the tire, and the tire will be illustrated and described in detail based on their embodiments.

[0017] <Definition> The compounds described in this specification may be partially or entirely derived from fossil resources, may be derived from biological resources such as plant resources, or may be derived from recycled resources such as used tires. Further, it may be derived from a mixture of any two or more of fossil resources, biological resources, and recycled resources.

[0018] In this specification, the "ratio of sustainable materials" refers to the total mass ratio of materials derived from biological resources (biomass resources) and materials derived from recycled resources (recycled resources) in the rubber composition for the case member, the case member of the tire, and the tire.

[0019] In this specification, the biological resources (biomass resources) refer to carbon-neutral organic resources derived from organisms, and include, for example, those stored in the form of starch or cellulose, the bodies of animals that grow by eating plants, and products obtained by processing plants and animals, etc., and are resources excluding fossil resources (oil, coal, natural gas, etc.). The biological resources may be edible or inedible, but preferably inedible so as not to compete with food and from the viewpoint of effective utilization of resources.

[0020] Specific examples of the biological resources include, for example, cellulosic crops (pulp, kenaf, wheat straw, rice straw, waste paper, paper-making residues, etc.), wood, charcoal, compost, food waste, vegetable oil residues, fishery residues, livestock excrement, food waste, sewage sludge, natural rubber, cotton, oils and fats (palm oil, castor oil, cottonseed oil, soybean oil, linseed oil, rapeseed oil, coconut oil, peanut oil, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, coconut oil, etc.), carbohydrate crops (corn, wheat, rice, rice husks, rice bran, old rice, tubers, buckwheat, cassava, sago palm, sugarcane, etc.), bagasse (i.e., the residue after squeezing sugarcane juice), soybeans, okara, essential oils (pine root oil, orange oil, eucalyptus oil, etc.), pulp black liquor, algae, etc. As the biological resources, those obtained by treating these (i.e., substances derived from biological resources) can also be used. Examples of the treatment methods include biological treatment methods that utilize the functions of microorganisms, plants, animals, and tissue cultures thereof; chemical treatment methods that utilize acids, alkalis, catalysts, thermal energy, light energy, etc.; physical treatment methods such as micronization, compression, microwave treatment, electromagnetic wave treatment, etc. Further, as the biological resources, those extracted and purified from the biological resources or the treated biological resources (i.e., substances derived from biological resources) can also be used. For example, saccharides, proteins, amino acids, fatty acids, fatty acid esters, etc. purified from the biological resources can also be used. Examples of the saccharides include sucrose, glucose, trehalose, fructose, lactose, galactose, xylose, allose, talose, gulose, altrose, mannose, idose, arabinose, apiose, maltose, cellulose, starch, chitin, etc. derived from biological resources. Examples of the proteins include compounds formed by linking amino acids (preferably L-amino acids) derived from biological resources, and also include oligopeptides such as dipeptides. Examples of the amino acids include valine, leucine, isoleucine, arginine, lysine, asparagine, glutamine, phenylalanine, etc. derived from biological resources, and among these, valine, leucine, isoleucine, arginine, and phenylalanine are preferred.The amino acid may be an L - amino acid or a D - amino acid, but from the perspective of high abundance in nature and easy availability, L - amino acids are preferred. Examples of the fatty acid include butyric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc. derived from biological resources. Examples of the fatty acid ester include vegetable oils, animal oils, modified products of oils and fats derived from biological resources, etc. These biological resources may contain various materials and impurities.

[0021] In this specification, the recycled resources refer to resources obtained by recycling products that have been used once, or collected without being used, or discarded. For example, recycled resources include resources obtained by recycling used rubber products such as used tires.

[0022] <Rubber Composition for Tire Case Member> The rubber composition for a tire case member of the present embodiment is characterized by containing a rubber component (A) and at least one resin component (B) selected from the group consisting of terpene resins and rosin resins.

[0023] As described above, generally, in a rubber composition for a tire case member, a resin component such as a petroleum resin is blended to improve tack (adhesiveness) and make it easier to adhere to adjacent members, thereby improving workability in the molding of green tires. In contrast, in the rubber composition for a tire case member of the present embodiment, at least one resin component (B) selected from the group consisting of terpene resins and rosin resins is blended to improve tack (adhesiveness). In the rubber composition for a tire case member of the present embodiment, since terpene resins and rosin resins are materials derived from biological resources (biomass resources), by blending at least one resin component (B) selected from the group consisting of terpene resins and rosin resins into the rubber composition for a tire case member, the ratio of the tire case member and the sustainable material of the tire to which the rubber composition is applied can be improved. As described above, when a rubber composition with a high resin content is applied to the tire case member, the case rigidity of the tire tends to decrease. However, the terpene resin and rosin resin used in the rubber composition for the tire case member of the present embodiment have higher tack (adhesiveness) than the generally used petroleum resin, so that equivalent tack (adhesiveness) can be imparted in a small amount. And, by blending a small amount of at least one resin component (B) selected from the group consisting of terpene resins and rosin resins, a decrease in the case rigidity of the tire can be suppressed compared to the generally used petroleum resin. Therefore, according to the rubber composition for the tire case member of the present embodiment, the ratio of the sustainable material of the tire can be improved while maintaining the productivity and performance of the tire.

[0024] (Rubber component (A)) The rubber composition for the tire case member of the present embodiment contains a rubber component (A), and the rubber component (A) provides rubber elasticity to the composition. The rubber component (A) preferably has a sustainable rate of 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. Here, the "sustainable rate" of the rubber component (A) is the total mass ratio of the component derived from biological resources (biomass resources) and the component derived from recycled resources (recycled resources) in the rubber component (A).

[0025] As the rubber component (A), the rubber derived from the biological resources and the rubber derived from the recycled resources are preferable. Here, the ratio of the monomer component derived from biological resources in 100 mol% of the monomer components constituting the rubber derived from biological resources is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%. In addition, the proportion of the monomer component derived from the recycled resource in 100 mol% of the monomer components constituting the rubber derived from the recycled resource is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may even be 100 mol%.

[0026] The rubber component (A) is a component that contributes to crosslinking. Usually, the weight average molecular weight (Mw) is 10,000 or more, preferably 50,000 or more, more preferably 150,000 or more, still more preferably 200,000 or more. Also, it is preferably 5,000,000 or less, more preferably 2,000,000 or less, still more preferably 1,500,000 or less, and even more preferably 1,300,000 or less. In this specification, the weight average molecular weight (Mw) of the rubber component (A) can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0027] As the rubber component (A), a diene rubber is preferred. Among the diene rubbers, isoprene rubber and butadiene rubber are preferred. Here, the isoprene rubber refers to a rubber containing units derived from isoprene as monomer units, and the butadiene rubber refers to a rubber containing units derived from butadiene as monomer units.

[0028] Examples of the isoprene rubber include natural rubber (NR), synthetic isoprene rubber (IR), modified natural rubber (modified NR), denatured natural rubber (denatured NR), denatured synthetic isoprene rubber (denatured IR), and the like. As the natural rubber (NR), for example, those commonly used in the tire industry such as RSS#3 and TSR20 (e.g., SIR20 and STR20) can be used. The origin of the natural rubber (NR) is not particularly limited, and examples include those derived from Hevea brasiliensis, guayule, and Russian dandelion. The synthetic isoprene rubber (IR) is not particularly limited, and for example, those commonly used in the tire industry such as IR2200 can be used. Examples of the modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of the denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of the denatured IR include epoxidized synthetic isoprene rubber, hydrogenated synthetic isoprene rubber, and grafted synthetic isoprene rubber. These isoprene rubbers may be used alone or in combination of two or more. Among these, NR is preferred as the isoprene rubber.

[0029] The isoprene rubber preferably has a sustainability rate of 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. In order to make the sustainability rate of the isoprene rubber within the above range, it is preferable to use natural rubber (NR) or a polymer synthesized using isoprene derived from biological resources or isoprene derived from recycled resources as a monomer component. At this time, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from recycled resources, a copolymer of a monomer derived from biological resources and a monomer derived from recycled resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from recycled resources and a monomer derived from fossil resources (such as petroleum).

[0030] The rubber component (A) preferably contains an isoprene skeleton rubber. The isoprene skeleton rubber is a rubber having an isoprene unit as a main skeleton. Specifically, the above-mentioned natural rubber (NR), synthetic isoprene rubber (IR), modified natural rubber (modified NR), modified natural rubber (modified NR), modified synthetic isoprene rubber (modified IR), etc. are exemplified. By the rubber component (A) containing an isoprene skeleton rubber, the breaking strength of the case member of the tire can be increased. As a result, the fracture resistance of the tire provided with the case member can be improved.

[0031] Examples of the butadiene rubber include butadiene rubber (BR), aromatic vinyl compound-butadiene copolymer rubber (for example, styrene-butadiene rubber (SBR)), etc. Here, the butadiene serving as a raw material for the butadiene rubber is preferably derived from biological resources or recycled resources.

[0032] Examples of the butadiene rubber (BR) include a butadiene rubber having a high cis content, a butadiene rubber having a low cis content, a butadiene rubber containing syndiotactic polybutadiene crystals, etc. As the butadiene rubber (BR), commercially available products can be used. Examples of the commercially available products of the butadiene rubber include products of UBE Elastomer Co., Ltd., ENEOS Materials Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. These butadiene rubbers may be used alone or in combination of two or more.

[0033] Examples of the aromatic vinyl compound-butadiene copolymer rubber (e.g., SBR) include, for example, emulsion polymerization aromatic vinyl compound-butadiene copolymer rubber (e.g., emulsion polymerization styrene-butadiene rubber (E-SBR)), solution polymerization aromatic vinyl compound-butadiene copolymer rubber (e.g., solution polymerization styrene-butadiene rubber (S-SBR)), and the like. In the aromatic vinyl compound-butadiene copolymer rubber, examples of the aromatic vinyl compound (aromatic vinyl monomer) include styrene, vinylnaphthalene, divinylnaphthalene, and the like. These aromatic vinyl compounds may be used alone or in combination of two or more. Among these, styrene is preferable, and styrene derived from biomass resources and styrene derived from recycled resources are particularly preferable. That is, as the aromatic vinyl compound-butadiene copolymer rubber, SBR is preferable. Note that the styrene may have a substituent. As the aromatic vinyl compound-butadiene copolymer rubber, commercially available products can be used, and examples of the commercially available products include products of Asahi Kasei Corporation, ENEOS Materials Co., Ltd., Nippon Zeon Co., Ltd., Sumitomo Chemical Co., Ltd., and the like. These aromatic vinyl compound-butadiene copolymer rubbers may be used alone or in combination of two or more.

[0034] The butadiene-based rubber preferably has a sustainability rate of 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. In order to make the sustainable ratio of the butadiene rubber within the above range, for example, a polymer synthesized using butadiene derived from biological resources, butadiene derived from recycled resources, aromatic vinyl compounds derived from biological resources (e.g., styrene derived from biological resources), or aromatic vinyl compounds derived from recycled resources (e.g., styrene derived from recycled resources) as monomer components may be used. At this time, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from recycled resources, a copolymer of a monomer derived from biological resources and a monomer derived from recycled resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from recycled resources and a monomer derived from fossil resources (such as petroleum). Note that butadiene rubber (B-BR) derived from biological resources (biomass resources) and aromatic vinyl compound-butadiene copolymer rubber derived from biological resources (e.g., styrene-butadiene rubber (B-SBR) derived from biological resources (biomass resources)) include not only rubbers obtained by polymerizing butadiene or the like according to the conventional method, but also rubbers obtained by reactions by microorganisms, plants, animals, and tissue cultures thereof (hereinafter also referred to as "microorganisms, etc.") or enzymatic reactions.

[0035] In addition, in order to make the sustainable ratio of the entire rubber component (A) within the above range, it is preferable to use natural rubber (NR) as the rubber component (A), or a polymer synthesized using a monomer component derived from biological resources or a monomer component derived from recycled resources as monomer components.

[0036] Generally, the materials for tire rubber compositions (rubber and its monomers, fillers, resins, etc.) require large-scale manufacturing equipment for their production. Therefore, they are usually produced in large factories in specific regions and require a lot of energy for the storage and transportation of raw materials and products. In contrast, materials derived from biomass resources are derived from agricultural products, forests, etc. in each region and can be produced on a small scale through microbial fermentation and catalytic reactions. By utilizing the products and waste in each region, the energy required for the transportation and storage of raw materials can be reduced. Furthermore, the energy required for the transportation and storage of the manufactured materials to tire factories can also be reduced, which is environmentally friendly. In addition, materials derived from recycled resources can be obtained, for example, by disassembling and pyrolyzing used tires to extract the materials that make up the tires, such as rubber, fillers, and steel cords. In addition, there are also methods that include a desulfurization step of desulfurizing biomass resources or processed products of biomass resources to remove sulfur-containing substances from the biomass resources or processed products of biomass resources, a recovery step of recovering sulfur from the desulfurized treatment residue generated in the desulfurization step, and a processing step of processing the recovered sulfur into vulcanizing sulfur (for example, the method described in Japanese Patent Application No. 2022-140390). Sulfur can be obtained from biomass resources or processed products of biomass resources, and materials for tire rubber compositions can be obtained from various waste materials and used articles. In this way, by using sustainable materials (materials derived from biomass resources and materials derived from recycled resources), it is possible to comprehensively reduce the environmental impact in tire manufacturing, such as reducing the carbon dioxide emissions (LCCO2) throughout the life cycle, reducing the energy consumption (LCE) throughout the life cycle, reducing the costs (LCC) incurred throughout the life cycle, and reducing the usage of fossil resources.

[0037] In addition, when manufacturing the rubber composition, according to the supply situation of biological resources, renewable resources, and fossil resources (for example, monomer components derived from fossil resources) and / or market demands (for example, the demand for biological resources as food), the ratios of monomer components derived from biological resources, monomer components derived from renewable resources, and monomer components derived from fossil resources are appropriately selected, and the monomer components derived from biological resources, monomer components derived from renewable resources, and monomer components derived from fossil resources are polymerized to obtain a rubber derived from a sustainable material (a material derived from biological resources or a material derived from renewable resources) having the same performance as that when using a conventional synthetic rubber. When using a monomer component derived from a renewable resource, it may be difficult to separate it from a monomer component derived from a fossil resource due to reasons in the manufacturing process of the monomer. In that case, by adopting the concept of mass balance, the impact on the environment can be evaluated.

[0038] The ratio of each monomer unit (for example, a unit derived from isoprene, a unit derived from butadiene, a unit derived from an aromatic vinyl compound) in the total rubber component (A) can be adjusted as appropriate. The ratio of each monomer unit in the total rubber component (A) can be adjusted, for example, by appropriately combining the above-mentioned isoprene-based rubber and butadiene-based rubber. Also, the ratio of cis-bond units in the units derived from butadiene can be adjusted as appropriate. In this specification, "monomer unit" means a constitutional unit of a polymer, "unit derived from isoprene" means a constitutional unit in a polymer constituted based on the monomer isoprene (including isoprene units in natural rubber), "unit derived from butadiene" means a constitutional unit in a polymer constituted based on the monomer butadiene, and "unit derived from an aromatic vinyl compound" means a constitutional unit in a polymer constituted based on the monomer aromatic vinyl compound. Also, in this specification, the ratio of each monomer unit is measured by NMR.

[0039] The rubber component (A) may include diene rubbers such as the above-mentioned isoprene rubber, butadiene rubber (BR), aromatic vinyl compound-butadiene copolymer rubber (for example, SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), etc. These rubber components may be used alone or in combination of two or more.

[0040] Functional groups that interact with fillers such as carbon black and silica may be introduced into the rubber component (A) by modification. Examples of such functional groups include amino group, amide group, isocyanate group, imino group, imidazole group, urea group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, ether group, carbonyl group, oxycarbonyl group, silyl group, alkoxysilyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, etc. These functional groups may have substituents. These functional groups may be introduced into the rubber component alone or in combination of two or more. Among these, amino group, alkoxy group, and alkoxysilyl group are preferred, and a substituted amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and an alkoxysilyl group having 1 to 6 carbon atoms are more preferred.

[0041] The functional group can be introduced, for example, by reacting a compound (modifying agent) having the functional group with the rubber component. The functional group is a modified functional group having interactivity with fillers such as silica and carbon black, and examples thereof include nitrogen-containing functional groups, silicon-containing functional groups, oxygen-containing functional groups, and the like. Examples of the compound (modifying agent) having a nitrogen-containing functional group include amino group-containing compounds, examples of the compound (modifying agent) having a silicon-containing functional group include silicon halides, hydrocarbyloxysilane compounds, and the like, and examples of the compound (modifying agent) having an oxygen-containing functional group include alkoxy group-containing compounds, alkylene oxide group-containing compounds, trialkylsilyloxy group-containing compounds, and the like. More specifically, examples include the compounds described in International Publication No. WO2016 / 194316 and International Publication No. WO2019 / 117256. These modifying agents may be used alone or in combination of two or more.

[0042] The rubber derived from the sustainable material (material derived from biological resources or material derived from recycled resources) can be produced, for example, by using a monomer component derived from biological resources or a monomer component derived from recycled resources, and, if necessary, a monomer component derived from fossil resources, in the same manner as the production method of conventional synthetic rubber derived from fossil resources. Further, the rubber derived from the sustainable material (particularly, rubber derived from biological resources) can also be obtained by reactions by microorganisms or the like or enzymatic reactions.

[0043] Regarding the method for preparing biomass-derived rubber from the above-mentioned biomass resources, for example, the method described in JP-A-2022-179158 can be used. For example, by using butadiene obtained from biomass resources as a monomer component, butadiene rubber (B-BR) derived from biomass resources (biomass resources) can be obtained. Also, by using styrene obtained from biomass resources and butadiene obtained from biomass resources as monomer components, styrene-butadiene rubber (B-SBR) derived from biomass resources (biomass resources) can be obtained. Here, as methods for obtaining B-BR and B-SBR from biomass resources, in addition to the method of artificially polymerizing, methods of polymerizing in vivo, methods of polymerizing with bio-derived enzymes, etc. can be mentioned. The molecular weight, branching, microstructure, etc. of the obtained B-BR and B-SBR can be appropriately adjusted by changing the polymerization conditions according to the known methods according to the target tire performance.

[0044] As the butadiene obtained from the above-mentioned biomass resources, butadiene derived from alkyl alcohols (preferably ethanol and butanol, more preferably butanol), butadiene derived from alkenes (preferably ethylene), and butadiene derived from unsaturated carboxylic acids (preferably tiglic acid) can be preferably used. Also, two or more of these butadienes may be used in combination. Also, as the styrene obtained from the above-mentioned biomass resources, styrene obtained from plants (preferably plants belonging to the families Euphorbiaceae, Urticaceae, and Caryophyllaceae, more preferably plants belonging to the genera Euphorbia, Urtica, and Dianthus, still more preferably Euphorbia cotinifolia, Urtica thunbergiana, and Dianthus chinensis), styrene obtained from microorganisms (preferably microorganisms belonging to the genera Penicillium and Escherichia, more preferably P. citrinum, transformed E. coli) can be preferably used. Also, two or more of these styrenes may be used in combination.

[0045] Recently, biomass combinators centered on bioethanol, bioethylene, etc. have been planned. However, bioethanol and bioethylene are produced mainly using saccharides and / or celluloses as biomass resources, and other biomass resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, saccharides compete with food, and excessive use of celluloses leads to deforestation. Therefore, in addition to the supply situations of various biomass resources, in accordance with the supply situations of renewable resources, the supply situations of fossil resources, and market demands (for example, the demand for biomass resources as food), as monomer components derived from the biomass resources, it is preferable to use a plurality of types of monomer components derived from biomass resources, or to use in combination monomer components derived from biomass resources, monomer components derived from renewable resources, and monomer components derived from fossil resources, and further appropriately adjust the ratios of these monomer components for use. Thereby, it is possible to effectively utilize a wide range of biomass resources such as sugars, proteins, and lipids, as well as renewable resources, without relying on a single type of biomass resource, and it is also possible to stably supply rubber derived from sustainable materials, and furthermore, it is possible to consider the environment according to the situation during production. In addition, when using a plurality of types of monomer components derived from biomass resources, it is preferable to use monomer components derived from different biomass resources, that is, monomer components obtained from different biomass resources. Specifically, as butadiene derived from biomass resources, it is preferable to use a mixture of butadienes derived from a plurality of types of biomass resources with different origins, and / or as styrene derived from biomass resources, it is preferable to use a mixture of styrenes derived from a plurality of types of biomass resources with different origins. Thereby, a plurality of types of biomass resources can be effectively utilized.

[0046] (Resin component (B)) The rubber composition for the case member of the tire of the present embodiment contains at least one resin component (B) selected from the group consisting of terpene resins and rosin resins. As described above, terpene resins and rosin resins generally have higher tack (adhesiveness) than commonly used petroleum resins, so that equivalent tack (adhesiveness) can be imparted in a small amount. Further, by blending a small amount of terpene resin and rosin resin, a decrease in the case rigidity of the tire can be suppressed. Further, since terpene resins and rosin resins are naturally-derived sustainable resins, by blending terpene resins and / or rosin resins into the rubber composition for the case member of the tire, the ratio of the case member of the tire to which the rubber composition is applied and the sustainable material of the tire can be improved, and the environmental load can be further reduced.

[0047] The resin component (B) may be hydrogenated, that is, it may be a hydrogenated resin (hydrogenated resin). Further, the resin component (B) may be modified to introduce a functional group that interacts with fillers such as carbon black and silica. Examples of the functional group include amino group, amide group, isocyanate group, imino group, imidazole group, urea group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, ether group, carbonyl group, oxycarbonyl group, silyl group, alkoxysilyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, etc.

[0048] The terpene resin is a solid resin obtained by blending turpentine oil, which is obtained simultaneously when rosin is obtained from pine trees, or a polymerization component separated therefrom, and polymerizing it using a Friedel-Crafts type catalyst. Examples include β-pinene resin and α-pinene resin. The terpene resin also includes terpene-aromatic compound resins. Representative examples of the terpene-aromatic compound resins include terpene-phenol resins and styrene-terpene resins. The terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts type catalyst or by further condensing them with formalin. The styrene-terpene resin can be obtained by reacting styrene with terpenes using a Friedel-Crafts type catalyst. The raw material terpenes are not particularly limited, and monoterpene hydrocarbons such as α-pinene and limonene are preferred, those containing α-pinene are more preferred, and α-pinene is particularly preferred.

[0049] Examples of the rosin resin include natural resins such as gum rosin, tall oil rosin, and wood rosin contained in raw pine tar and tall oil, and modified rosins, rosin derivatives, and modified rosin derivatives such as polymerized rosin and its partially hydrogenated rosin; glycerin ester rosin, its partially hydrogenated rosin, and fully hydrogenated rosin; pentaerythritol ester rosin, its partially hydrogenated rosin, and polymerized rosin; and the like.

[0050] The resin component (B) preferably has a softening point of 30°C or higher, more preferably 60°C or higher, more preferably 80°C or higher, more preferably higher than 110°C, more preferably 116°C or higher, more preferably 120°C or higher, more preferably 123°C or higher, and even more preferably 127°C or higher. Also, from the viewpoint of processability, the resin component (B) preferably has a softening point of 160°C or lower, more preferably 150°C or lower, more preferably 145°C or lower, more preferably 141°C or lower, and even more preferably 136°C or lower. In this specification, the softening point of the resin component is the temperature at which the sphere drops when measured with a ring and ball softening point measuring device according to the softening point defined in JIS K 6220-1:2015 (ISO 28641:2010).

[0051] As the resin component (B), commercially available products can be used. Examples of commercially available products of the resin component (B) include products of Arakawa Chemical Industries, Ltd., Clayton, Yasuhara Chemical Co., Ltd., Arizona Chemical Co., etc.

[0052] When the rubber component (A) contains isoprene skeleton rubber, the resin component (B) preferably has a difference in SP value from the isoprene skeleton rubber of 0.6 (cal / cm 3 ) 1 / 2 or less, more preferably 0.58 (cal / cm 3 ) 1 / 2 or less. When the rubber component (A) contains isoprene skeleton rubber, a tire case member rubber composition in which the difference in SP value between the resin component (B) and the isoprene skeleton rubber is 0.6 (cal / cm 3 ) 1 / 2 or less has high compatibility between the rubber component (A) and the resin component (B), and thus is excellent in fracture resistance.

[0053] The content of the resin component (B) is preferably 0.5 to 30 parts by mass, more preferably 5 to 25 parts by mass, based on 100 parts by mass of the rubber component (A). When the content of the resin component (B) is 0.5 part by mass or more based on 100 parts by mass of the rubber component (A), the tack (adhesiveness) of the rubber composition is improved, and the workability in the molding of the green tire is improved. Also, when the content of the resin component (B) is 30 parts by mass or less based on 100 parts by mass of the rubber component (A), the case rigidity of the tire to which the rubber composition is applied to the case member is improved. Therefore, a tire case member rubber composition in which the content of the resin component (B) is 0.5 to 30 parts by mass based on 100 parts by mass of the rubber component (A) can improve the productivity and performance of the tire.

[0054] (Other resin components) The rubber composition for the case member of the tire of the present embodiment may contain resin components other than the terpene resin and rosin resin described above. Examples of the other resin components include C5 resins, C5-C9 resins, C9 resins, cyclopentadiene resins, aromatic resins, coumarone resins, indene resins, coumarone-indene resins, olefin resins, polyurethane resins, acrylic resins, and the like. These other resin components may be used alone or in combination of two or more.

[0055] The other resin components may be hydrogenated, that is, they may be hydrogenated resins. Further, functional groups that interact with fillers such as carbon black and silica may be introduced into the resin by modification. Examples of the functional groups include amino groups, amide groups, isocyanate groups, imino groups, imidazole groups, urea groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, ether groups, carbonyl groups, oxycarbonyl groups, silyl groups, alkoxysilyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, and the like.

[0056] Examples of the C5 resin include aliphatic petroleum resins obtained by (co)polymerizing a C5 fraction obtained by thermal decomposition of naphtha in the petrochemical industry. The C5 fraction usually contains olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, 3-methyl-1,2-butadiene.

[0057] The C5-C9 resin refers to a C5-C9 synthetic petroleum resin. Examples of the C5-C9 resin include C5-C 11Examples of the fraction to be retained include solid polymers obtained by polymerization using Friedel-Crafts catalysts such as AlCl3 and BF3. More specifically, examples include copolymers mainly composed of styrene, vinyltoluene, α-methylstyrene, indene, and the like. As the C5-C9 resin, a resin with less than C9 components is preferable from the viewpoint of compatibility with the rubber component. Here, "less than C9 components" means that the components of C9 or higher in the total amount of the resin are less than 50% by mass, preferably 40% by mass or less.

[0058] The C9 resin refers to a C9 synthetic petroleum resin, for example, a solid polymer obtained by polymerizing a C9 fraction using a Friedel-Crafts type catalyst such as AlCl3 or BF3. Examples of the C9 resin include copolymers mainly composed of indene, α-methylstyrene, vinyltoluene, and the like.

[0059] The cyclopentadiene resin refers to a resin containing units derived from cyclopentadiene monomers as monomer units. Examples of the cyclopentadiene resin include homopolymers of cyclopentadiene monomers, copolymers of two or more cyclopentadiene monomers, and copolymers of cyclopentadiene monomers and other monomers. Here, examples of the cyclopentadiene monomer include cyclopentadiene, dicyclopentadiene, tricyclopentadiene, and the like. Among these, dicyclopentadiene is preferable. That is, as the cyclopentadiene resin, a dicyclopentadiene resin is preferable. The dicyclopentadiene resin refers to a resin obtained by polymerizing dicyclopentadiene using, for example, a Friedel-Crafts type catalyst such as AlCl3 or BF3. Examples of the dicyclopentadiene resin include homopolymers of dicyclopentadiene, copolymers of dicyclopentadiene and aromatic monomers, and copolymers of dicyclopentadiene and C9 fractions (vinyltoluene, indene, etc.).

[0060] The aromatic resin refers to a resin containing units derived from aromatic monomers as monomer units. Examples of the aromatic resin include homopolymers of aromatic monomers, copolymers of two or more aromatic monomers, and copolymers of aromatic monomers and other monomers. Here, examples of the aromatic monomer include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-phenylstyrene; phenol-based monomers such as phenol, alkylphenol, alkoxyphenol; naphthol-based monomers such as naphthol, alkylnaphthol, alkoxynaphthol; and the like.

[0061] The other resin component preferably has a softening point of 30°C or higher, more preferably 60°C or higher, still more preferably 80°C or higher, even more preferably higher than 110°C, even more preferably 116°C or higher, even more preferably 120°C or higher, even more preferably 123°C or higher, and still more preferably 127°C or higher. Also, from the viewpoint of processability, the resin preferably has a softening point of 160°C or lower, more preferably 150°C or lower, still more preferably 145°C or lower, even more preferably 141°C or lower, and still more preferably 136°C or lower.

[0062] Commercially available products can be used as the other resin component. Examples of commercially available products of the resin include products of ENEOS Corporation, Arakawa Chemical Industries, Ltd., ExxonMobil Corporation, Crayton Corporation, Yasuhara Chemical Co., Ltd., Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF SE, Crayton Polymer Corporation, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., Tago Chemical Industry Co., Ltd., and the like.

[0063] The content of the other resin component is not particularly limited and can be appropriately adjusted according to, for example, the tire category of the application destination, the target performance, etc. For example, the content of the other resin component is preferably in the range of 5 to 100 parts by mass, more preferably in the range of 10 to 60 parts by mass, based on 100 parts by mass of the rubber component (A).

[0064] (Silica) The rubber composition for the case member of the tire of the present embodiment may contain silica. Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc. Among these, wet silica is preferred in terms of having many silanol groups. These silicas may be used alone or in combination of two or more. As the silica, commercially available products can be used, and as commercially available products of the silica, products of Tosoh Silica Co., Ltd., Evonik, Solvay, Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0065] As the silica, from the viewpoint of reducing environmental impact, silica derived from silicate plants is preferable. Such silicate plants are present, for example, in mosses, ferns, thistles, cucurbitaceae, nettle family, gramineous plants, etc. Among these plants, gramineous plants are preferable. Examples of the gramineous plants include rice, bamboo, sugarcane, etc., and among these, rice is preferable. Since rice is widely cultivated for food, it can be procured locally in a wide area. Also, since a large amount of rice husks are generated as industrial waste, it is easy to secure the quantity. Therefore, from the viewpoint of easy availability, as the silica, silica derived from rice husks (hereinafter also referred to as "rice husk silica") is particularly preferable. By using the rice husk silica, rice husks that become industrial waste can be effectively utilized, and since the raw material can be procured locally near a tire manufacturing factory, the energy and cost of transportation and storage can be reduced, which is preferable from various viewpoints in terms of the environment. The rice husk silica may be powder of rice husk charcoal obtained by carbonizing rice husks by heating, or it may be precipitated silica produced by a wet method using an aqueous alkali silicate solution prepared by extracting rice husk ash generated when rice husks are burned in a biomass boiler using the rice husks as fuel with an alkali. The method for producing the rice husk charcoal is not particularly limited, and various known methods can be used. For example, rice husk charcoal can be obtained by thermally decomposing rice husks by steaming them using a kiln. The rice husk charcoal thus obtained can be pulverized using a known pulverizer (for example, a ball mill), and sorted and classified into a predetermined particle size range to obtain powder of rice husk charcoal. Also, the precipitated silica derived from rice husks can be produced by the method described in JP-A-2019-38728, etc. Also, as the silica, from the viewpoint of reducing environmental impact, it is also preferable to use silica obtained by extracting and recycling the silicate component from the edge material of a silicon wafer that is a raw material for semiconductors or from a glass bottle, etc. and using it in production.

[0066] The silica preferably has a nitrogen adsorption specific surface area (N2SA) of 50 m 2 / g or more, more preferably 100 m 2 / g or more, still more preferably 150 m 2 / g or more, and also preferably 350 m 2It is preferably below / g, and 250 m 2 It is more preferably below / g, and 230 m 2 It is still more preferably below / g, and 200 m 2 It is even more preferably below / g. In addition, in this specification, the nitrogen adsorption specific surface area (N2SA) of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0067] The content of the silica can be appropriately adjusted, for example, according to the tire category to which it is applied, the target performance, etc. For example, the content of the silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 30 parts by mass or more, more preferably 50 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, even more preferably 100 parts by mass or more, particularly preferably 110 parts by mass or more, with respect to 100 parts by mass of the rubber component (A). Also, it is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 180 parts by mass or less, and particularly preferably 150 parts by mass or less.

[0068] (Silane coupling agent) When the rubber composition for the case member of the tire of the present embodiment contains silica, in order to improve the effect of the silica, it is preferable that the rubber composition contains a silane coupling agent. Examples of the silane coupling agent include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropylbenzothiazolyl tetrasulfide, etc. As the silane coupling agent, commercially available products can be used. Examples of the commercially available products of the silane coupling agent include products of Evonik, Momentive, Shin-Etsu Silicone Co., Ltd., Toray Dow Corning Co., Ltd., Tokyo Chemical Industry Co., Ltd., Admax Co., Ltd., etc. These silane coupling agents may be used alone or in combination of two or more.

[0069] In addition, bioethanol can also be used as a raw material for the silane coupling agent. Bioethanol is mainly produced from saccharides and / or celluloses as biological resources, and other biological resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, saccharides compete with food, and excessive use of celluloses leads to deforestation. Therefore, depending on the supply situation of various biological resources, the supply situation of renewable resources, the supply situation of fossil resources, and market requirements (for example, the demand for biomass resources as food), as the raw material for the silane coupling agent, it is preferable to use multiple types of ethanol derived from biological resources (bioethanol), or to use ethanol derived from biological resources (bioethanol), ethanol derived from renewable resources, and ethanol derived from fossil resources in combination. This enables the effective utilization of a wide range of biological resources such as sugars, proteins, and lipids, as well as renewable resources, without relying on a single type of biological resource, and also allows for environmental considerations according to the manufacturing situation.

[0070] The content of the silane coupling agent can be appropriately adjusted, for example, according to the tire category of the application destination, target performance, etc. For example, the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 6 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the silica.

[0071] (Carbon black) The rubber composition for the case member of the tire of the present embodiment preferably contains carbon black. As the carbon black, carbon black derived from plants and carbon black obtained by recycling (i.e., recycled carbon black) are particularly preferable. Examples of carbon black derived from plants include those derived from castor oil and rosin oil. Examples of recycled carbon black include carbon black obtained by decomposing (particularly, thermal decomposition) crosslinked rubber products such as used tires, and carbon black obtained from waste oil.

[0072] Regarding the crosslinked rubber products used for the decomposition, they may be grouped by the types of rubber components previously compounded, and then the decomposition process may be carried out for each group. Also, they may be grouped by the types of fillers previously compounded (for example, the types of carbon black, the types of silica, the mixing ratio of carbon black and silica, etc.), and the decomposition process may be carried out for each group. Furthermore, after grouping both by the types of rubber components and by the types of fillers, the decomposition process may be carried out for each group. When the decomposition process is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained. Therefore, when compounded into rubber components again, a rubber composition with better performance can be obtained.

[0073] Also, when the crosslinked rubber products used for the decomposition are derived from tires, they may be grouped in advance by tire type (for example, for passenger cars, for trucks and buses, for large vehicles such as off-road, for aircraft, for agricultural vehicles, etc.), and then the decomposition process may be carried out for each group. Also, they may be grouped in advance by tire member (for example, tread rubber, sidewall rubber, bead rubber, steel cord coating rubber, organic fiber coating rubber, pad rubber, cushion rubber, etc.), and then the decomposition process may be carried out for each group. Furthermore, after grouping both by tire type and by tire member, the decomposition process may be carried out for each group. When the decomposition process is carried out for each group in this way, recycled carbon black with more uniform physical properties can be obtained. Therefore, when compounded into rubber components again, a rubber composition with better performance can be obtained.

[0074] The grade of the carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. As the carbon black, commercially available products can be used. Examples of commercially available products of the carbon black include products of Asahi Carbon Co., Ltd., Cabot Japan Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Birla Carbon, etc. These carbon blacks may be used alone or in combination of two or more.

[0075] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, target performance, etc. For example, the nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 20 m 2 / g or more, more preferably 50 m 2 / g or more, still more preferably 70 m 2 / g or more, even more preferably 90 m 2 / g or more, and preferably 200 m 2 / g or less, more preferably 150 m 2 / g or less, still more preferably 130 m 2 / g or less. In this specification, the nitrogen adsorption specific surface area (N2SA) of the carbon black is determined according to JIS K 6217-2:2017 (ISO 4652:2012).

[0076] The content of the carbon black is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, target performance, etc. For example, the content of the carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component (A).

[0077] The proportion of silica in the total content of the silica and carbon black is not particularly limited and can be appropriately adjusted according to, for example, the applicable tire category, target performance, etc. For example, the proportion of silica in the total content of silica and carbon black is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Also, the proportion of silica in the total content of silica and carbon black may be 100% by mass, but is preferably 98% by mass or less.

[0078] (rubber powder) The rubber composition for the case member of the tire of the present embodiment may contain rubber powder. The rubber powder is obtained by pulverizing used rubber products such as used tires, and if desired, removing reinforcing materials such as steel materials and fibers, dusts, glasses, sands, stones, etc., or preparing a newly vulcanized rubber composition for producing rubber powder and pulverizing it. For example, rubber powder can be obtained from vulcanized rubber by the method described in "Rubber Chemistry And Technology". In the step of obtaining rubber powder by pulverizing vulcanized rubber, mechanical treatment or cryogenic treatment may be used. For example, in mechanical treatment, various crushing devices such as a cracker mill and a granulator can be used to mechanically pulverize vulcanized rubber into fine particles. Also, in cryogenic treatment, finely ground vulcanized rubber is frozen at an extremely low temperature and then pulverized into fine particles. Also, a magnetic separator etc. can be used for removing steel materials, and an air classifier etc. can be used for removing fibers. As the rubber powder, commercially available products can also be used, and examples of commercially available products of the rubber powder include products of Global Corporation or Nantong Huili Rubber Corporation etc. From the viewpoint of reducing environmental load, it is preferable to use rubber powder obtained by pulverizing used rubber products such as used tires. The rubber powder may be used alone or in combination of two or more kinds.

[0079] The composition of the rubber powder is not particularly limited and depends on the composition of the vulcanized rubber such as used rubber products (used tires) as raw materials. In one embodiment, the rubber powder contains a rubber component, carbon black, silica, etc. The rubber component, carbon black, silica, etc. contained in the rubber powder may be the same as or different from the rubber component, carbon black, silica, etc. that can be contained in the rubber composition for the case member of the tire of the present embodiment described above.

[0080] The rubber powder preferably has a volume average particle diameter of 1000 μm or less, more preferably 500 μm or less, still more preferably 200 μm or less, and even more preferably 100 μm or less. Also, the smaller the volume average particle diameter of the rubber powder, the more preferable, and the lower limit is not particularly limited. In this specification, the volume average particle diameter is measured by a laser diffraction particle size distribution measuring device and can be measured using, for example, "CAPA500" manufactured by Horiba, Ltd.

[0081] The rubber powder preferably has a residue on a 60-mesh sieve of less than 1% by mass, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, and the lower limit is not particularly limited. Also, the rubber powder preferably has a residue on an 80-mesh sieve of less than 10% by mass, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and the lower limit is not particularly limited. In this specification, the sieve residue is measured according to ASTM D5644-01.

[0082] The rubber powder preferably has an acetone extract of 12% by mass or less, more preferably 11% by mass or less, still more preferably 10% by mass or less. Also, it is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass or more. In this specification, the acetone extract in the rubber powder refers to the acetone extract (%) determined by the acetone extraction method conforming to JIS K6350.

[0083] The content of the rubber powder is not particularly limited and can be appropriately adjusted according to, for example, the tire category of the application destination, the target performance, etc. For example, the content of the rubber powder is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 200 parts by mass or less, more preferably 150 parts by mass or less, more preferably 100 parts by mass or less, more preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component (A).

[0084] (Liquid softening agent) The rubber composition for the case member of the tire of the present embodiment may contain a liquid softening agent. Here, the "liquid softening agent" is a compounding agent that is liquid at 25°C (room temperature) and has an effect of softening the rubber composition. The liquid softening agent is not particularly limited, and examples thereof include oils and liquid polymers. Among these, oils are preferred. These liquid softening agents may be used alone or in combination of two or more.

[0085] The "oil" is a general term for the extender oil contained in the rubber component and the liquid oil added as a compounding agent for the rubber composition. Examples thereof include vegetable oil, process oil, oil obtained by recycling vegetable oil or process oil, or a mixture thereof. From the viewpoint of reducing environmental impact, as the oil, vegetable oil or oil obtained by recycling is preferred. Examples of the vegetable oil include palm oil, castor oil, cottonseed oil, soybean oil, linseed oil, rapeseed oil, coconut oil, peanut oil, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, coconut oil and the like. Examples of the process oil include paraffinic process oil, aromatic process oil, naphthenic process oil and the like. As the oil, commercially available products can be used, and as commercially available products of the oil, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Seiyu Co., Ltd., Nisshin Oillio Group Co., Ltd. and the like can be used. These oils may be used alone or in combination of two or more.

[0086] As the liquid polymer, a liquid diene polymer is preferred. Examples of the liquid diene polymer include liquid styrene-butadiene copolymer (liquid SBR), liquid polybutadiene (liquid BR), liquid polyisoprene (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid styrene-butadiene-styrene block copolymer (liquid SBS block polymer), liquid styrene-isoprene-styrene block copolymer (liquid SIS block polymer), liquid polyfarnesene, liquid farnesene-butadiene copolymer and the like. These liquid polymers may be hydrogenated or the terminals or main chains may be modified with functional groups (polar groups). These liquid polymers may be used alone or in combination of two or more.

[0087] The content of the liquid softener is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, target performance, etc. For example, the content of the liquid softener is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 100 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component (A).

[0088] (Antioxidant) The rubber composition for the case member of the tire of the present embodiment may contain an antioxidant. Examples of the antioxidant include N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer (TMDQ), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW), 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline, and the like. As the antioxidant, commercially available products can be used, and as commercially available products of the antioxidant, products of Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., Seiko Chemical Co., Ltd., Flexsys Co., Ltd., etc. can be used. These antioxidants may be used alone or in combination of two or more.

[0089] The content of the antioxidant is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, target performance, etc. For example, the content of the antioxidant is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, and preferably 12 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less with respect to 100 parts by mass of the rubber component (A).

[0090] (Wax) The rubber composition for the case member of the tire of the present embodiment may contain wax. Examples of the wax include natural waxes such as plant waxes and animal waxes; petroleum waxes such as paraffin wax and microcrystalline wax; synthetic waxes such as polymers of ethylene and polymers of propylene; and the like. As the wax, commercially available products can be used, and as commercially available products of the wax, products of Seiko Chemical Co., Ltd., Nippon Seiro Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., etc. can be used. These waxes may be used alone or in combination of two or more.

[0091] The content of the wax is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, the target performance, etc. For example, the content of the wax is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component (A).

[0092] (Stearic acid) The rubber composition for the case member of the tire of the present embodiment may contain stearic acid. As the stearic acid, commercially available products can be used, and as commercially available products of the stearic acid, products of NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acids Co., Ltd., etc. can be used. These commercially available products of stearic acid may be used alone or in combination of two or more.

[0093] The content of the stearic acid is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, the target performance, etc. For example, the content of the stearic acid is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component (A).

[0094] (Zinc oxide) The rubber composition for the case member of the tire of the present embodiment may contain zinc oxide (zinc white). As the zinc oxide, not only zinc ingot but also zinc oxide obtained from recycled zinc or zinc dross (that is, obtained by recycling) is preferable. As the zinc oxide, commercially available products can be used, and as the commercially available products of the zinc oxide, products of Hakusuitech Co., Ltd., Shoindo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., etc. can be used. These commercially available zinc oxides may be used alone or in combination of two or more.

[0095] The content of the zinc oxide is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, target performance, etc. For example, the content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component (A).

[0096] (Sulfur) The rubber composition for the case member of the tire of the present embodiment preferably contains sulfur. As the sulfur, those derived from fossil resources, those derived from recycled resources, those obtained by treating bioresource-derived materials, etc. can be used, and from the viewpoint of reducing environmental impact, it is particularly preferable to use sulfur obtained from waste derived from bioresources. Examples of the method for obtaining sulfur from waste derived from bioresources include, for example, the method described in the above-mentioned Japanese Patent Application No. 2022-140390. Also, as the sulfur, powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are generally used as crosslinking agents in the rubber industry, may be used. As the sulfur, commercially available products can be used, and as the commercially available products of the sulfur, products of Tsurumi Chemical Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys Co., Ltd., etc. can be used. These sulfurs may be used alone or in combination of two or more.

[0097] The sulfur content is not particularly limited and can be appropriately adjusted according to, for example, the target tire category and target performance. For example, the sulfur content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, still more preferably 0.8 parts by mass or more, and preferably 8 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component (A).

[0098] (Vulcanization accelerator) The rubber composition for the case member of the tire of the present embodiment preferably contains a vulcanization accelerator. The vulcanization accelerator can be used regardless of whether it is derived from fossil resources, recycled resources, or biological resources, but from the perspective of reducing environmental impact, it is preferably derived from biological resources. The vulcanization accelerator derived from biological resources can be obtained, for example, by the method disclosed in JP-A-2005-139239. Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide; guanidine-based vulcanization accelerators such as 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, o-tolylbiguanidine; thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (M), di-2-benzothiazolyl disulfide (MBTS, DM); thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetra stearyl thiuram disulfide, tetrabenzyl thiuram disulfide (TBzTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N). As the vulcanization accelerator, commercially available products can be used, and as commercially available products of the vulcanization accelerator, products of Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., etc. can be used. These vulcanization accelerators may be used alone or in combination of two or more.

[0099] The content of the vulcanization accelerator is not particularly limited and can be appropriately adjusted depending on, for example, the tire category of the application destination, the target performance, etc. For example, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and preferably 8 parts by mass or less, more preferably 6 parts by mass or less, still more preferably 5.5 parts by mass or less with respect to 100 parts by mass of the rubber component (A).

[0100] (Cellulose nanofiber) The rubber composition for the case member of the tire of the present embodiment may contain cellulose nanofibers (CNF). The cellulose nanofibers can reinforce the rubber composition by being blended therein. As the cellulose nanofibers, modified cellulose nanofibers are preferable, and the modified cellulose nanofibers are fine fibers made from modified cellulose as a raw material. The fiber diameter of the cellulose nanofibers is not particularly limited, but is about 3 to 500 nm. The average fiber diameter and average fiber length of the cellulose nanofibers can be obtained by averaging the fiber diameter and fiber length obtained from the results of observing each fiber using a scanning electron microscope (SEM), an atomic force microscope (AFM), or a transmission electron microscope (TEM). The cellulose nanofibers can be obtained by defibrating cellulose. Further, the average fiber length and average fiber diameter of the fine fibers can be adjusted by oxidation treatment and defibrating treatment.

[0101] The raw material of the cellulose nanofiber only needs to contain cellulose and is not particularly limited. For example, plants (such as wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), sun-dried kraft pulp (BKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animals (such as tunicates), algae, microorganisms (such as acetic acid bacteria (Acetobacter)), microbial products, etc. can be mentioned. These cellulose raw materials may be used alone or in combination of two or more.

[0102] The content of the cellulose nanofiber is not particularly limited and can be appropriately adjusted according to, for example, the tire category of the application destination, the target performance, etc. For example, the content of the cellulose nanofiber is preferably in the range of 1 to 100 parts by mass, more preferably in the range of 5 to 70 parts by weight, and still more preferably in the range of 10 to 40 parts by mass with respect to 100 parts by mass of the rubber component (A).

[0103] (Others) In addition to the above-mentioned components, the rubber composition for the case member of the tire of the present embodiment may further contain various additives generally used in the tire industry, such as fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc.; organic peroxides; etc. The content of these additives is not particularly limited and can be appropriately adjusted according to, for example, the tire category of the application destination, the target performance, etc. For example, the range of 0.1 to 200 parts by mass is preferable with respect to 100 parts by mass of the rubber component (A).

[0104] (Method for manufacturing rubber composition) The manufacturing method of the rubber composition for the tire case member of the present embodiment is not particularly limited. For example, at least one resin component (B) selected from the group consisting of terpene resins and rosin resins is blended with the rubber component (A), and various components appropriately selected as needed are blended, followed by kneading, heat treatment, extrusion, etc., to manufacture it. Further, by vulcanizing the obtained rubber composition, a vulcanized rubber can be obtained.

[0105] The conditions for the kneading are not particularly limited, and various conditions such as the charging volume of the kneading apparatus, the rotation speed of the rotor, the ram pressure, etc., and the kneading temperature, kneading time, type of kneading apparatus, etc. can be appropriately selected according to the purpose. As the kneading apparatus, usually, a Banbury mixer, an internal mixer, a kneader, a roll, etc. used for kneading rubber compositions can be mentioned.

[0106] Regarding the conditions for the heat treatment, there are also no particular restrictions, and various conditions such as the heat treatment temperature, heat treatment time, heat treatment apparatus, etc. can be appropriately selected according to the purpose. As the heat treatment apparatus, usually, a heat treatment roll machine used for heat treatment of rubber compositions can be mentioned.

[0107] Regarding the conditions for the extrusion, there are also no particular restrictions, and various conditions such as the extrusion time, extrusion speed, extrusion apparatus, extrusion temperature, etc. can be appropriately selected according to the purpose. As the extrusion apparatus, usually, an extruder used for extrusion of rubber compositions can be mentioned. The extrusion temperature can be determined appropriately.

[0108] Regarding the apparatus, method, conditions, etc. for performing the vulcanization, there are also no particular restrictions, and they can be appropriately selected according to the purpose. As the apparatus for performing the vulcanization, usually, a molding vulcanizer using a mold used for vulcanization of rubber compositions can be mentioned. As the conditions for vulcanization, the temperature is, for example, about 100 to 190°C.

[0109] <Tire case member> The tire case member of the present embodiment is characterized by including the above-described rubber composition for the tire case member. Since the case member of the tire of the present embodiment contains the rubber composition for the case member of the tire of the present embodiment described above, by applying it to the tire, it is possible to improve the ratio of the sustainable material of the tire while maintaining the productivity and performance of the tire. Examples of the case member include carcass ply, wire chafer, etc.

[0110] <Tire> The tire of the present embodiment is characterized by including the above-described case member of the tire. Since the tire of the present embodiment includes the case member of the tire of the present embodiment described above, the ratio of the sustainable material is improved while maintaining the productivity and performance.

[0111] Next, an embodiment of the tire of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment of the tire of the present invention. The tire 1 of the present embodiment shown in FIG. 1 has a pair of bead portions 2, a pair of sidewall portions 3, and a tread portion 4 continuous with both sidewall portions 3. It extends in a toroidal shape between the pair of bead portions 2 and includes a carcass 5 that reinforces these portions 2, 3, 4, a belt 6 disposed on the outer side in the tire radial direction of the crown portion of the carcass 5, and a wire chafer 7 disposed outside the carcass 5 at the bead portion 2.

[0112] The carcass 5 of the tire 1 shown in FIG. 1 is composed of one carcass ply formed by coating a plurality of cords arranged in parallel with coating rubber. The carcass 5 also includes a main body portion that extends in a toroidal shape between bead cores 8 respectively embedded in the bead portions 2, and a folded-back portion that is wound radially outward from the inner side to the outer side in the tire width direction around each bead core 8. However, in the tire of the present invention, the number of plies and the structure of the carcass 5 are not limited to this.

[0113] Also, the belt 6 of the tire 1 shown in FIG. 1 consists of two belt layers 6A and 6B. However, in the tire of the present invention, the number of belt layers constituting the belt 6 is not limited to this, and the number of belt layers may be three or more. Here, the belt layers 6A and 6B usually consist of a rubber-coated layer of cords (preferably steel cords) that extend obliquely with respect to the tire equatorial plane. The two belt layers 6A and 6B are laminated so that the cords constituting the belt layers 6A and 6B cross each other with the tire equatorial plane therebetween to form the belt 6.

[0114] Also, the wire chafer 7 of the tire 1 shown in FIG. 1 is disposed outside the carcass 5 (i.e., on the side opposite to the bead core 8 side of the carcass 5), particularly along the outer peripheral surface of the folded-back portion of the carcass 5. The wire chafer 7 is formed by coating a plurality of cords (such as steel-coated cords) arranged in parallel with a coating rubber and is disposed along the tire circumferential direction. Note that the wire chafer 7 of the tire 1 shown in FIG. 1 is one, but it may be two or more. Also, a tire in which the wire chafer 7 is omitted is also one embodiment of the tire of the present invention.

[0115] And in the tire 1 of the present embodiment, the coating rubber of the carcass ply and / or the wire chafer 7 constituting the carcass 5 uses the rubber composition for the case member of the tire of the present embodiment described above. Therefore, the tire 1 of the present embodiment has an improved ratio of sustainable materials while maintaining productivity and performance.

[0116] The tire of the present embodiment can be manufactured by a conventional method using the above-described rubber composition for carcass ply, case members such as wire chafers, etc. For example, the tire of the present embodiment may be obtained by vulcanizing after molding using an unvulcanized rubber composition according to the type of tire to be applied, or may be obtained by further fully vulcanizing after molding using a semi-vulcanized rubber that has undergone a pre-vulcanization process or the like. Note that the tire of the present embodiment is preferably a pneumatic tire, and as the gas to be filled in the pneumatic tire, in addition to normal air or air with adjusted oxygen partial pressure, inert gases such as nitrogen, argon, and helium can be used.

Examples

[0117] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples in any way.

[0118] <Preparation and Evaluation of Rubber Composition> The rubber compositions of the examples and comparative examples are prepared according to the compounding formulations shown in Table 1. For the obtained rubber compositions, the total mass ratio of the materials derived from biomass resources and the materials derived from recycled resources is calculated to calculate the sustainable material ratio. The results are shown in Table 1.

[0119]

Table 1

[0120] *1 Natural rubber: TSR20 *2 BR: Butadiene rubber, manufactured by JSR Corporation, trade name "BR01" *3 SBR: Styrene-butadiene rubber, manufactured by JSR Corporation, trade name "T0150" *4 Carbon black: Manufactured by Asahi Carbon Co., Ltd., trade name "Asahi #65" *5 C5-based resin: Manufactured by Nippon Zeon Co., Ltd., trade name "Quinton G100" *6 Terpene-based resin: Manufactured by Kraton Corporation, trade name "SYLVATRAXX8125" *7 Anti-aging agent (A): 2,2,4-trimethyl-1,2-dihydroquinoline polymer, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Nocrack 224" *8 Anti-aging agent (B): N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Nocrack 6C" *9 Vulcanization accelerator (A): N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Nocceler (registered trademark) CZ-G" *10 Vulcanization accelerator (B): Di-2-benzothiazolyldisulfide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., trade name "Nocceler (registered trademark) DM-P"

[0121] From Table 1, it can be seen that the rubber composition of the examples according to the present invention has an improved ratio of sustainable materials.

[0122] [Contribution to the Sustainable Development Goals (SDGs) led by the United Nations] Towards the realization of a sustainable society, the SDGs have been proposed. One embodiment of the present invention can be considered as a technology that contributes to, for example, "No. 12_The responsibility to create, the responsibility to use" and "No. 13_Specific measures against climate change".

Explanation of symbols

[0123] 1: Tire 2: Bead part 3: Sidewall part 4: Tread part 5: Carcass 6: Belt 6A, 6B: Belt layer 7: Wire chafer 8: Bead core

Claims

Claim 1 a rubber component (A); and at least one resin component (B) selected from the group consisting of terpene resins and rosin resins, the rubber composition for a tire case member, characterized by containing the same. Claim 2 The rubber composition for a tire case member according to Claim 1, wherein the content of the resin component (B) is 0.5 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). Claim 3 The rubber composition for a tire case member according to Claim 1, wherein the rubber component (A) contains an isoprene skeleton rubber. Claim 4 The resin component (B) has an SP value difference from the isoprene skeleton rubber of 0.6 (cal / cm ３ ) １／２ or less, the rubber composition for a case member of a tire according to claim 3. Claim 5 A tire case member, characterized by containing the rubber composition for a tire case member according to Claim 1. Claim 6 A tire, characterized by comprising the tire case member according to Claim 5.

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