Coating rubber composition for RFID tags, and tire

Abstract

To provide a coating rubber composition for RFID tags that is capable of improving the ratio of sustainable materials used in tires, and also to provide a tire with an improved ratio of sustainable materials used therein.SOLUTION: A coating rubber composition for RFID tags includes a rubber component (A) and silica (B), where the silica (B) includes plant-derived silica (B1), and the content of the silica (B) is 45 pts.mass or more relative to 100 pts.mass of the rubber component (A). A tire 1 has an RFID tag 12 coated with the coating rubber composition for RFID tags.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, it has been proposed to attach an RFID (Radio Frequency Identification) tag to a tire and write or read various information such as the tire's manufacturing history, distribution history, and usage history to the RFID tag in order to manage the tire individually (Patent Document 1). The RFID tag is usually covered with a coating rubber in order to be disposed in a tire mainly made of rubber members, and the coating rubber for the RFID tag is required to have various properties such as crack resistance, adhesion to adjacent rubber members, appropriate elastic modulus, etc. in addition to communication performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent No. 1580041 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, in recent years, from the perspective of social sustainability, there has been a demand to increase the proportion of so-called sustainable materials, such as materials derived from biological resources (biomass resources) and materials derived from renewable resources (recycled resources), in the various components used in tires. However, the use of sustainable materials for the coating rubber for RFID tags has not been considered until now.

[0005] Therefore, an object of the present invention is to provide a coating rubber composition for RFID tags that can increase the proportion of sustainable materials in tires. Another object of the present invention is to provide a tire with an improved proportion of sustainable materials. [Means for solving the problem]

[0006] The essential features of the coating rubber composition for RFID tags and the tire of the present invention that solve the above problems are as follows.

[0007] [1] A rubber composition comprising a rubber component (A) and silica (B), The silica (B) contains plant-derived silica (B1), A coating rubber composition for RFID tags, characterized in that the content of the silica (B) is 45 parts by mass or more per 100 parts by mass of the rubber component (A). The coating rubber composition for RFID tags of the present invention described in [1] above can increase the proportion of sustainable materials in tires.

[0008] [2] The coating rubber composition for RFID tags according to [1], further comprising a silane coupling agent (C). The coating rubber composition for RFID tags described in [2] above has further improved crack resistance and elastic modulus.

[0009] [3] The coating rubber composition for RFID tags according to [2], wherein the content of the silane coupling agent (C) is 5 to 20 mass % of the content of the silica (B). The coating rubber composition for RFID tags described in [3] above has further improved crack resistance and elastic modulus.

[0010] [4] The coating rubber composition for RFID tags according to any one of [1] to [3], wherein the content of the silica (B) is 45 to 90 parts by mass per 100 parts by mass of the rubber component (A). The coating rubber composition for RFID tags described in [4] above has further improved crack resistance and elastic modulus.

[0011] [5] The coating rubber composition for RFID tags according to any one of [1] to [4], wherein the plant-derived silica (B1) is silica derived from a grass family plant. In the coating rubber composition for RFID tags described in [5] above, the silica derived from grasses can be procured locally near tire manufacturing plants, which reduces the energy and costs involved in transportation and storage, and is therefore environmentally friendly from various standpoints.

[0012] [6] The coating rubber composition for RFID tags according to [5], wherein the plant-derived silica (B1) is silica derived from rice husks. In the coating rubber composition for RFID tags described in [6] above, rice husk-derived silica is generated in large quantities as industrial waste, so it is easy to secure the amount. In addition, since the raw material can be procured locally near tire manufacturing plants, it is possible to reduce the energy and costs for transportation and storage, which is environmentally favorable from various standpoints.

[0013] [7] The coating rubber composition for RFID tags according to any one of [1] to [6], wherein the content of carbon black is 15 parts by mass or less per 100 parts by mass of the rubber component (A). The coating rubber composition for RFID tags described in [7] above has a low relative dielectric constant and can extend the communication distance of RFID tags.

[0014] [8] The coating rubber composition for RFID tags according to any one of [1] to [7], wherein the content of silica (B) in the total content of the silica (B) and the carbon black is 80 to 100 mass%. The coating rubber composition for RFID tags described in [8] above has improved crack resistance and elastic modulus, and has a low dielectric constant, which enables the communication distance of RFID tags to be extended.

[0015] [9] A tire comprising an RFID tag coated with the coating rubber composition for RFID tags according to any one of [1] to [8]. The tire of the present invention described in [9] above has an increased proportion of sustainable materials. Effect of the Invention

[0016] According to the present invention, it is possible to provide a coating rubber composition for RFID tags that can increase the proportion of sustainable materials in tires. Furthermore, according to the present invention, it is possible to provide a tire with an improved proportion of sustainable materials. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of one embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The coating rubber composition for RFID tags and the tire of the present invention will be described in detail below with reference to the embodiments.

[0019] <Definition> The compounds described herein may be derived in whole or in part from fossil sources, from biological sources such as plant sources, from recycled sources such as used tires, or from a mixture of two or more of fossil sources, biological sources, and / or renewable sources.

[0020] In this specification, the "proportion of sustainable materials" refers to the total mass ratio of materials derived from biological resources (biomass resources) and materials derived from renewable resources (recycled resources) in the target RFID tag coating rubber composition and tire.

[0021] In this specification, the biological resources (biomass resources) refer to carbon-neutral organic resources derived from living 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 or animals, and are resources other than fossil resources (petroleum, coal, natural gas, etc.). The biological resources may be edible or non-edible, but are preferably non-edible from the viewpoint of not competing with food and of effective resource utilization.

[0022] Specific examples of the biological resources include cellulosic crops (pulp, kenaf, wheat straw, rice straw, waste paper, papermaking residues, etc.), wood, charcoal, compost, food waste, vegetable oil residues, fishery residues, livestock waste, food waste, wastewater 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 ... Examples of the biological resources include crops (corn, wheat, rice, rice husks, rice bran, old rice, potatoes, buckwheat, cassava, sago palm, sugarcane, etc.), bagasse (i.e., the residue after squeezing juice from sugarcane), soybeans, soybean pulp, essential oils (pine oil, orange oil, eucalyptus oil, etc.), pulp black liquor, algae, etc. The biological resources may be processed (i.e., biological resource-derived substances). Examples of the processing methods include biological processing methods that utilize the functions of microorganisms, plants, animals, and tissue cultures thereof; chemical processing methods that utilize acids, alkalis, catalysts, thermal energy, light energy, etc.; physical processing methods such as micronization, compression, microwave processing, and electromagnetic wave processing; and the like. The biological resources may also be extracted and refined from the biological resources or biological resources that have been processed (i.e., biological resource-derived substances). For example, sugars, proteins, amino acids, fatty acids, fatty acid esters, etc., purified from the biological resources can be used. Examples of the sugars 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 derived from biological resources and formed by linking amino acids (preferably L-amino acids), including 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 viewpoint of its abundance in nature and ease of availability, an L-amino acid is 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.

[0023] In this specification, the recycled resource refers to a resource obtained by recycling a product that has 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.

[0024] <Coating Rubber Composition for RFID Tag> The coating rubber composition for RFID tag of this embodiment contains a rubber component (A) and silica (B). And in the coating rubber composition for RFID tag of this embodiment, the silica (B) contains plant-derived silica (B1), and the content of the silica (B) is 45 parts by mass or more with respect to 100 parts by mass of the rubber component (A).

[0025] A general rubber composition contains carbon black, but carbon black increases the relative dielectric constant of the rubber composition, shortens the communication distance (communicable distance) of the RFID tag, and reduces the communication performance. Here, if carbon black is not used, the crack resistance and elastic modulus of the rubber composition will decrease. In contrast, the coating rubber composition for RFID tags of this embodiment contains silica (B), which, unlike carbon black, does not increase the relative dielectric constant of the rubber composition, and therefore can increase the communication distance of the RFID tag and improve the communication performance. In addition, by making the content of silica (B) 45 parts by mass or more relative to 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus of the rubber composition can be sufficiently ensured. In addition, by making the rubber composition have a sufficient elastic modulus, stress concentration on the RFID tag coated with the rubber composition can be suppressed, and adhesion between the rubber composition (coating) and an adjacent rubber member can be ensured. Therefore, the coating rubber composition for RFID tags of this embodiment can sufficiently balance communication performance, crack resistance, adhesion to an adjacent rubber member, and elastic modulus.

[0026] Regarding the communication performance, the dielectric constant of the rubber composition at 860 MHz can be measured using a dielectric constant measuring device. Also, since it is known from past results of dielectric constant measurements that the dielectric constant can be estimated from the amount of carbon black in the rubber compound, the dielectric constant can also be calculated.

[0027] In addition, in the coating rubber composition for RFID tags of this embodiment, the plant-derived silica (B1) is a material derived from biological resources (biomass resources), so the coating rubber composition for RFID tags of this embodiment has an improved ratio of sustainable materials. Therefore, by applying an RFID tag coated with the coating rubber composition for RFID tags of this embodiment to a tire, it is possible to improve the ratio of sustainable materials in the tire. In a rubber composition containing a rubber component (A) and silica (B) in which the content of silica (B) is 45 parts by mass or more per 100 parts by mass of rubber component (A), even if the silica (B) contains plant-derived silica (B1), the performance such as communication performance is not impaired.

[0028] (Rubber component (A)) The coating rubber composition for RFID tags of this embodiment contains a rubber component (A), which provides rubber elasticity to the composition. The rubber component (A) has a sustainability rate of preferably 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, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. Here, the "sustainability rate" of the rubber component (A) refers to the total mass ratio of components derived from biological resources (biomass resources) and components derived from recycled resources (recycled resources) in the rubber component (A).

[0029] As the rubber component (A), the rubber derived from biological resources and the rubber derived from recycled resources are preferred. Here, the proportion of the monomer components 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, even more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%. The proportion of monomer components derived from recycled resources in 100 mol% of monomer components constituting the rubber derived from recycled resources is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and may be 100 mol%.

[0030] The rubber component (A) is a component that contributes to crosslinking, and usually has a weight average molecular weight (Mw) of 10,000 or more, preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and preferably 5,000,000 or less, more preferably 2,000,000 or less, 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, for example, by converting the weight average molecular weight (Mw) into standard polystyrene based on a measurement value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0031] The rubber component (A) is preferably a diene rubber, and the diene rubber is preferably an isoprene rubber or a butadiene rubber, where the isoprene rubber refers to a rubber containing a unit derived from isoprene as a monomer unit, and the butadiene rubber refers to a rubber containing a unit derived from butadiene as a monomer unit.

[0032] Examples of the isoprene-based rubber include natural rubber (NR), synthetic isoprene rubber (IR), modified natural rubber (modified NR), modified natural rubber (modified NR), and modified synthetic isoprene rubber (modified IR). Examples of the natural rubber (NR) that can be used include those commonly used in the tire industry, such as RSS#3 and TSR20 (e.g., SIR20 and STR20). The origin of the natural rubber (NR) is not particularly limited, and examples of the natural rubber include those derived from Hevea brasiliensis, guayule, and Russian dandelion. Examples of the synthetic isoprene rubber (IR) are not particularly limited, and examples of the synthetic isoprene rubber that can be used include those commonly used in the tire industry, such as IR2200. Examples of the modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of the modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. The modified IR includes epoxidized synthetic isoprene rubber, hydrogenated synthetic isoprene rubber, grafted synthetic isoprene rubber, etc. These isoprene-based rubbers may be used alone or in combination of two or more. Among these, NR is preferred as the isoprene-based rubber.

[0033] The isoprene-based rubber preferably has a sustainability rate of 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass. In order to set the sustainability rate of the isoprene-based 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 renewable resources as a monomer component. In this case, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from renewable resources, a copolymer of a monomer derived from biological resources and a monomer derived from renewable resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from renewable resources and a monomer derived from a fossil resource (petroleum, etc.).

[0034] Examples of the butadiene rubber include butadiene rubber (BR), aromatic vinyl compound-butadiene copolymer rubber (for example, styrene-butadiene rubber (SBR)), etc. Here, butadiene, which is a raw material for butadiene rubber, is preferably derived from biological resources or recycled resources.

[0035] Examples of the butadiene rubber (BR) include high cis content butadiene rubber, low cis content butadiene rubber, and butadiene rubber containing syndiotactic polybutadiene crystals. Commercially available products can be used as the butadiene rubber (BR), and examples of commercially available butadiene rubbers include products from UBE Elastomers Co., Ltd., ENEOS Materials Corporation, Asahi Kasei Co., Ltd., and Zeon Corporation. These butadiene rubbers may be used alone or in combination of two or more.

[0036] Examples of the aromatic vinyl compound-butadiene copolymer rubber (e.g., SBR) include emulsion-polymerized aromatic vinyl compound-butadiene copolymer rubber (e.g., emulsion-polymerized styrene-butadiene rubber (E-SBR)), solution-polymerized aromatic vinyl compound-butadiene copolymer rubber (e.g., solution-polymerized 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 preferred, and styrene derived from biological resources and styrene derived from recycled resources are particularly preferred. That is, the aromatic vinyl compound-butadiene copolymer rubber is preferably SBR. 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 from Asahi Kasei Corporation, ENEOS Materials Corporation, Nippon Zeon Corporation, 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.

[0037] The butadiene-based rubber has a sustainability rate of preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass. In order to make the sustainability rate of the butadiene-based rubber fall within the above range, for example, a polymer synthesized using butadiene derived from biological resources, butadiene derived from renewable resources, aromatic vinyl compounds derived from biological resources (e.g., styrene derived from biological resources), and aromatic vinyl compounds derived from renewable resources (e.g., styrene derived from renewable resources) as monomer components may be used. In this case, the synthesized polymer may be a homopolymer of a monomer derived from biological resources, a homopolymer of a monomer derived from renewable resources, a copolymer of a monomer derived from biological resources and a monomer derived from renewable resources, or a copolymer of a monomer derived from biological resources and / or a monomer derived from renewable resources and a monomer derived from a fossil resource (petroleum, etc.). In addition, the 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 rubber obtained by polymerizing butadiene, etc. according to a conventional method, but also rubber obtained by reactions or enzyme reactions caused by microorganisms, plants, animals, and tissue cultures thereof (hereinafter also referred to as "microorganisms, etc.").

[0038] In order to set the sustainability rate 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 monomer components derived from biological resources or monomer components derived from recycled resources as monomer components.

[0039] Generally, materials for rubber compositions for tires (rubber and its monomers, fillers, resins, etc.) require large-scale manufacturing equipment for their production, and are therefore usually produced in large factories in specific regions, and a lot of energy is required for the storage and transportation of raw materials and products. In contrast, materials derived from biological resources (biomass resources) are derived from agricultural products, forests, etc. in each region, and can be produced on a small scale by fermentation of microorganisms and catalytic reactions, so by utilizing products and waste from each region, the energy required for the transportation and storage of raw materials can be reduced, and further the energy required for the transportation and storage of the produced materials to tire factories can also be reduced, which is environmentally friendly. In addition, materials derived from regenerated resources (recycled resources) can be obtained, for example, by dismantling and pyrolyzing used tires to extract materials that constitute tires, such as rubber, fillers, and steel cords. In addition, sulfur can be obtained from biological resources or processed products of biological resources by a method including a desulfurization step of desulfurizing biological resources or processed products of biological resources to remove sulfur-containing substances from the biological resources or processed products of biological resources, a recovery step of recovering sulfur from the desulfurization residue generated in the desulfurization step, and a processing step of processing the recovered sulfur into sulfur for vulcanization (for example, the method described in Japanese Patent Application No. 2022-140390), and materials for rubber compositions for tires can be obtained from various wastes and used items. In this way, by using sustainable materials (materials derived from biological resources or materials derived from recycled resources), it is possible to reduce the overall environmental load in tire manufacturing, such as reducing carbon dioxide emissions (LCCO2) over the entire life cycle, reducing energy consumption (LCE) over the entire life cycle, reducing costs (LCC) incurred over the entire life cycle, and reducing the amount of fossil resources used.

[0040] In addition, when producing the rubber composition, the ratio of the monomer components derived from biological resources, the monomer components derived from renewable resources, and the monomer components derived from fossil resources can be appropriately selected according to the supply situation of biological resources, recycled resources, and fossil resources (e.g., monomer components derived from fossil resources) and / or market demand (e.g., demand for biological resources as food), and the monomer components derived from biological resources, the monomer components derived from renewable resources, and the monomer components derived from fossil resources can be polymerized to obtain rubber derived from sustainable materials (materials derived from biological resources or materials derived from renewable resources) having performance equivalent to that of conventional synthetic rubber. When using monomer components derived from renewable resources, it may be difficult to separate them from monomer components derived from fossil resources due to the manufacturing process of the monomer. In that case, the impact on the environment can be evaluated by adopting the concept of mass balance.

[0041] The ratio of each monomer unit (e.g., unit derived from isoprene, unit derived from butadiene, unit derived from aromatic vinyl compound) in the entire rubber component (A) can be adjusted appropriately depending on the component to which the rubber is applied. The ratio of each monomer unit in the entire rubber component can be adjusted, for example, by appropriately combining the above-mentioned isoprene-based rubber and butadiene-based rubber. In addition, the ratio of cis-bond units in the butadiene-based units can also be adjusted appropriately depending on the component to which the rubber is applied. In this specification, the term "monomer unit" refers to a structural unit of a polymer, the term "unit derived from isoprene" refers to a structural unit in a polymer constituted based on the monomer isoprene (including the isoprene unit in natural rubber), the term "unit derived from butadiene" refers to a structural unit in a polymer constituted based on the monomer butadiene, and the term "unit derived from an aromatic vinyl compound" refers to a structural unit in a polymer constituted based on the monomer aromatic vinyl compound. In this specification, the ratio of each monomer unit is measured by NMR.

[0042] The rubber component (A) may contain diene rubbers such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), etc., in addition to the above-mentioned isoprene-based rubber, butadiene rubber (BR), and aromatic vinyl compound-butadiene copolymer rubber (e.g., SBR). These rubber components may be used alone or in combination of two or more.

[0043] The rubber component (A) may be modified to introduce a functional group that interacts with a filler such as carbon black or silica. Examples of the functional group include amino, amide, isocyanate, imino, imidazole, urea, ammonium, imide, hydrazo, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxy, epoxy, ether, carbonyl, oxycarbonyl, silyl, alkoxysilyl, mercapto, sulfide, disulfide, sulfonyl, sulfinyl, and thiocarbonyl groups, and these functional groups may have a substituent. These functional groups may be introduced into the rubber component alone or in combination of two or more. Among these, an amino group, an alkoxy group, and an alkoxysilyl group are preferred, and a substituted amino group in which a hydrogen atom of an 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.

[0044] The functional group can be introduced, for example, by reacting a compound (modifier) ​​having the functional group with the rubber component (A). The functional group is a modified functional group having an interactive property with a filler such as silica or carbon black, and examples thereof include a nitrogen-containing functional group, a silicon-containing functional group, and an oxygen-containing functional group. Examples of compounds (modifiers) having a nitrogen-containing functional group include amino group-containing compounds, and examples of compounds (modifiers) having a silicon-containing functional group include silicon halides and hydrocarbyloxysilane compounds. Examples of compounds (modifiers) having an oxygen-containing functional group include alkoxy group-containing compounds, alkylene oxide group-containing compounds, and trialkylsilyloxy group-containing compounds. More specifically, examples of the compounds include those described in International Publication No. 2016 / 194316 and International Publication No. 2019 / 117256. These modifiers may be used alone or in combination of two or more.

[0045] The rubber derived from sustainable materials (materials derived from biological resources or materials derived from renewable resources) can be produced in the same manner as conventional synthetic rubber derived from fossil resources, for example, by using monomer components derived from biological resources or monomer components derived from renewable resources, and, if necessary, monomer components derived from fossil resources. The rubber derived from sustainable materials (particularly rubber derived from biological resources) can also be obtained by reactions with microorganisms or enzyme reactions.

[0046] Regarding the method for preparing rubber derived from biological resources from the above-mentioned biological resources, for example, the method described in JP 2022-179158 A can be used. For example, by using butadiene obtained from biological resources as a monomer component, it is possible to obtain butadiene rubber (B-BR) derived from biological resources (biomass resources), and by using styrene obtained from biological resources and butadiene obtained from biological resources as monomer components, it is possible to obtain styrene-butadiene rubber (B-SBR) derived from biological resources (biomass resources). Here, methods for obtaining B-BR and B-SBR from biological resources include, in addition to artificial polymerization methods, methods of polymerization in vivo, and methods of polymerization with biological enzymes. 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 known methods according to the target tire performance.

[0047] As the butadiene obtained from the biological 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 suitably used. Two or more of these butadienes may be used in combination. As the styrene obtained from the biological resources, styrene obtained from a plant (preferably a plant belonging to the family Hamamelidaceae, Styraxaceae, or Apocynaceae, more preferably a plant belonging to the genera Liquidamus, Styrax, or Catharanthus, and even more preferably Sweetgum, Styrax rosa, or Catharanthus roseus) or a microorganism (preferably a microorganism belonging to the genera Penicillium or Escherichia, more preferably P. citrinum or transformed E. coli) can be suitably used. Two or more of these styrenes may be used in combination.

[0048] Recently, biomass combinat mainly using bioethanol, bioethylene, etc. are planned, but bioethanol and bioethylene are mainly produced using sugars and / or cellulose as biological resources, and other biological resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, sugars compete with food, and excessive use of cellulose leads to deforestation. Therefore, it is preferable to use multiple types of monomer components derived from biological resources as the monomer components derived from the biological resources, or to use monomer components derived from biological resources, monomer components derived from renewable resources, and monomer components derived from fossil resources in combination, and further to appropriately adjust the ratio of these monomer components. This makes it possible to effectively utilize a wide range of biological resources and renewable resources such as sugars, proteins, and lipids without relying on one type of biological resource, and to stably supply rubber derived from sustainable materials, and further to consider the environment depending on the situation at the time of production. In addition, when using multiple types of monomer components derived from biological resources, it is preferable to use monomer components derived from different biological resources, i.e., monomer components obtained from different biological resources. Specifically, it is preferable to use a mixture of butadiene derived from multiple types of biological resources with different origins as the butadiene derived from biological resources, and / or to use a mixture of styrene derived from multiple types of biological resources with different origins as the styrene derived from biological resources. This allows multiple types of biological resources to be effectively utilized.

[0049] (Silica (B)) The coating rubber composition for RFID tags of this embodiment contains silica (B), and the content of the silica (B) is 45 parts by mass or more relative to 100 parts by mass of the rubber component (A). By blending the silica (B) in the rubber composition, the crack resistance and elastic modulus of the rubber composition can be improved without increasing the relative dielectric constant of the rubber composition, but if the content of the silica (B) is less than 45 parts by mass relative to 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus of the rubber composition are insufficient. Note that the relative dielectric constant of the rubber composition is preferably 4.0 or less, more preferably 2.5 or less, from the viewpoint of the communication distance (communicable distance) of the RFID tag.

[0050] The content of the silica (B) is preferably 45 to 100 parts by mass, more preferably 45 to 90 parts by mass, and particularly preferably 60 to 80 parts by mass, per 100 parts by mass of the rubber component (A). When the content of the silica (B) is 60 parts by mass or more per 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus of the rubber composition can be further improved. When the content of the silica (B) is less than 45 parts by mass per 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus are reduced. When the content of the silica (B) is 45 to 100 parts by mass per 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus of the rubber composition can be further improved. When the content of the silica (B) is 45 to 90 parts by mass per 100 parts by mass of the rubber component (A), the crack resistance and elastic modulus of the rubber composition can be further improved.

[0051] The silica (B) contains plant-derived silica (B1). The plant-derived silica (B1) is a material derived from a biological resource (biomass resource), and thus the proportion of sustainable materials in the coating rubber composition for RFID tags is increased by containing the plant-derived silica (B1). By applying the rubber composition to tires, the proportion of sustainable materials in the tires can be increased, and the environmental impact can be reduced.

[0052] As the silica derived from plants (B1), silica derived from silicic acid plants is preferred from the viewpoint of reducing environmental load. The silicic acid plants are present, for example, in mosses, ferns, horsetails, Cucurbitaceae, Urticaceae, and Gramineae plants. Among these plants, Gramineae plants are preferred, that is, as the silica derived from plants (B1), silica derived from Gramineae plants is preferred. Gramineae-derived silica can be procured locally as raw material near tire manufacturing plants, and therefore can reduce energy and costs for transportation and storage, which is environmentally preferable from various viewpoints. Examples of the Gramineae plant include rice, bamboo grass, sugarcane, etc., and among these, rice is preferred. Rice is widely cultivated for food, so it can be procured locally in a wide area, and rice husks are generated in large quantities as industrial waste, so it is easy to secure the amount. Therefore, from the viewpoint of availability, silica derived from rice husks (hereinafter also referred to as "rice husk silica") is particularly preferred as plant-derived silica (B1). 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 the tire manufacturing plant, energy and costs for transportation and storage can be reduced, which is environmentally preferable from various viewpoints. The rice husk silica may be a powder of rice husk charcoal obtained by carbonizing rice husks by heating, or may be precipitated silica produced by a wet method using an alkali silicate aqueous solution, which is prepared by extracting rice husk ash generated when rice husks are burned as fuel in a biomass boiler with an alkali and extracting the rice husk ash with an alkali silicate aqueous solution. The method for producing the rice husk charcoal is not particularly limited, and various known methods can be used. For example, rice husks can be pyrolyzed by steaming them in a kiln to obtain rice husk charcoal. The rice husk charcoal thus obtained is pulverized using a known pulverizer (for example, a ball mill), and then sorted and classified into a predetermined particle size range to obtain rice husk charcoal powder. The rice husk-derived precipitated silica can be produced by the method described in JP 2019-38728 A.

[0053] The ratio of the plant-derived silica (B1) in the silica (B) is preferably 5% by mass or more, more preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 45% by mass or more, and most preferably 100% by mass. By making the ratio of the plant-derived silica (B1) in the silica (B) 5% by mass or more, the ratio of sustainable materials in the coating rubber composition for RFID tags is improved, and by applying the rubber composition to a tire, the ratio of sustainable materials in the tire can be further improved.

[0054] The silica (B) may contain silica other than the above-mentioned plant-derived silica (B1). Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, etc., and among these, wet silica is preferred because it has a large number of silanol groups. These silicas other than the plant-derived silica (B1) may be used alone or in combination of two or more. As the silica other than the plant-derived silica (B1), commercially available products can be used, and examples of the commercially available silica include products from Tosoh Silica Co., Ltd., Evonik, Solvay, Solvay Japan Co., Ltd., Tokuyama Corporation, etc.

[0055] From the viewpoint of reducing the environmental load, it is also preferable to use, as the silica (B), silica obtained by extracting silicic acid components from scraps of silicon wafers, which are the raw material for semiconductors, glass bottles, etc., and recycling the extracted silica for use in the production.

[0056] The plant-derived silica (B1) has a nitrogen adsorption specific surface area (N2SA) of 50 m 2 / g or more, and 2 / g or more is more preferable, and 150m 2 / g or more is more preferable, and 2 / g or less, and 2 / g or less is more preferable, 2 / g or less is more preferable, 2It is even more preferable that the molecular weight is not more than 1 / g. In this specification, the nitrogen adsorption specific surface area (N2SA) of silica (B) is a value measured by the BET method in accordance with ASTM D3037-93.

[0057] (Silane coupling agent (C)) The coating rubber composition for RFID tags of this embodiment preferably further contains a silane coupling agent (C). When the rubber composition contains the silane coupling agent (C), the interaction between the rubber component (A) and the silica (B) becomes large, and the dispersibility of the silica (B) in the rubber component (A) is improved. In addition, the dispersibility of the silica (B) in the rubber component (A) is improved, and the action of the silica (B) is fully exerted, so that the crack resistance and elastic modulus of the rubber composition can be further improved.

[0058] Examples of the silane coupling agent (C) 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-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl- Examples of the tetrasulfide include N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, and dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide. As the silane coupling agent (C), a commercially available product can be used, and examples of the commercially available silane coupling agent (C) that can be used include products from Evonik, Momentive, Shin-Etsu Silicones Co., Ltd., Dow Corning Toray Co., Ltd., Tokyo Chemical Industry Co., Ltd., and Azumax Co., Ltd. These silane coupling agents may be used alone or in combination of two or more.

[0059] Bioethanol can also be used as a raw material for the silane coupling agent (C). Bioethanol is produced mainly using sugars and / or cellulose as biological resources, and other biological resources such as proteins, lipids, and amino acids cannot be effectively utilized. Furthermore, sugars compete with food, and excessive use of cellulose leads to deforestation. Therefore, it is preferable to use multiple types of ethanol (bioethanol) derived from biological resources as the raw material for the silane coupling agent, or to use ethanol (bioethanol) derived from biological resources, ethanol derived from renewable resources, and ethanol derived from fossil resources in combination, depending on the supply status of various biological resources, the supply status of renewable resources, the supply status of fossil resources, and market demands (for example, the demand for biomass resources as food). This makes it possible to effectively utilize a wide range of biological resources and renewable resources such as sugars, proteins, and lipids without relying on one type of biological resource, and also to consider the environment depending on the situation at the time of production.

[0060] The content of the silane coupling agent (C) is preferably 5 to 20 mass% of the content of the silica (B) (i.e., 5 to 20 mass parts per 100 mass parts of silica (B)). When the content of the silane coupling agent (C) is 5 mass% or more of the content of the silica (B), the compounding effect of the silane coupling agent (C) becomes large, and the dispersibility of the silica (B) in the rubber component (A) is further improved, and the crack resistance and elastic modulus of the rubber composition can be further improved. When the content of the silane coupling agent (C) is 20 mass% or less of the content of the silica (B), the gelation of the rubber component (A) can be suppressed. When the content of the silane coupling agent (C) is 5 to 20 mass% of the content of the silica (B), the crack resistance and elastic modulus of the rubber composition can be further improved.

[0061] (Vulcanizing agent) The coating rubber composition for RFID tags of the present embodiment preferably contains a vulcanizing agent. By containing the vulcanizing agent, the rubber composition can be vulcanized, and the crack resistance and elastic modulus of the rubber composition are improved. Examples of the vulcanizing agent include sulfur.

[0062] The sulfur may be derived from fossil resources, recycled resources, or materials derived from biological resources. From the viewpoint of reducing the environmental load, it is particularly preferable to use sulfur obtained from waste derived from biological resources. Examples of a method for obtaining sulfur from waste derived from biological resources include the method described in the above-mentioned Japanese Patent Application No. 2022-140390. In addition, the sulfur may be powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, or the like, which are generally used as crosslinking agents in the rubber industry. Here, the sulfur preferably contains insoluble sulfur. Insoluble sulfur is sulfur insoluble in carbon disulfide (amorphous polymeric sulfur), and is less soluble in the rubber component (A) than soluble sulfur, and is less likely to cause blooming. The proportion of insoluble sulfur in sulfur is preferably 50% by mass or more, and preferably 90% by mass or less, from the viewpoint of further improving the workability during tire molding. The sulfur may be a commercially available product, and examples of the commercially available sulfur include products from Tsurumi Chemical Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Co., Ltd., etc. These sulfurs may be used alone or in combination of two or more.

[0063] The content of the vulcanizing agent is preferably 5 parts by mass or more and 9 parts by mass or less based on 100 parts by mass of the rubber component (A) from the viewpoint of further improving the crack resistance and elastic modulus of the rubber composition.

[0064] (Vulcanization accelerator) The coating rubber composition for RFID tags of the present embodiment preferably contains a vulcanization accelerator. When the rubber composition contains a vulcanization accelerator, the vulcanization speed increases, and the elastic modulus of the rubber composition can be improved. The vulcanization accelerator can be derived from fossil resources, recycled resources, or biological resources, but is preferably derived from biological resources from the viewpoint of reducing environmental load. The vulcanization accelerator derived from biological resources can be obtained by the method disclosed in, for example, JP 2005-139239 A.

[0065] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine (DPG), and the like. Examples of the vulcanization accelerators include guanidine and o-tolyl biguanidine; thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole (M) and di-2-benzothiazolyl disulfide (MBTS, DM); thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrastearylthiuram disulfide, tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); and dithiocarbamate-based vulcanization accelerators. Among these, sulfenamide-based or guanidine-based vulcanization accelerators are preferred. Among the sulfenamide-based vulcanization accelerators, N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS) is particularly preferred. Among the guanidine-based vulcanization accelerators, 1,3-diphenylguanidine (DPG) is particularly preferred. As the vulcanization accelerator, commercially available products can be used, and examples of the commercially available vulcanization accelerator include products from Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., etc. These vulcanization accelerators may be used alone or in combination of two or more.

[0066] The content of the vulcanization accelerator is preferably 0.0 to 3.0 parts by mass, and more preferably 0.9 to 2.5 parts by mass, per 100 parts by mass of the rubber component (A), from the viewpoint of increasing the vulcanization rate of the rubber composition and further increasing the elastic modulus of the rubber composition.

[0067] (oil) The coating rubber composition for an RFID tag of this embodiment preferably contains oil. When the rubber composition contains oil, the rubber composition is better held together during kneading, and workability during kneading of the rubber composition is improved.

[0068] The oil is a general term for the extender oil contained in the rubber component and the liquid oil added as a compounding agent of the rubber composition, and examples thereof include petroleum-based softeners such as aromatic oils, paraffinic oils, and naphthenic oils, vegetable oils, process oils, oils obtained by recycling vegetable oils and process oils, and mixtures thereof. Among these, petroleum-based softeners such as aromatic oils, paraffinic oils, and naphthenic oils are preferred from the viewpoint of crack resistance and elastic modulus. In addition, from the viewpoint of reducing environmental load, vegetable oils and oils obtained by recycling are preferred. Examples of the vegetable oils 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, and coconut oil. Examples of the process oil include paraffin-based process oil, aromatic process oil, naphthenic process oil, etc. Commercially available products can be used as the oil, and examples of the commercially available oil include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. These oils may be used alone or in combination of two or more.

[0069] The oil is preferably a naphthenic oil containing asphalt. When the rubber composition contains a naphthenic oil containing asphalt, the rubber composition is more easily mixed and the workability during mixing of the rubber composition is further improved. The naphthenic oil containing asphalt is preferably a mixture of naphthenic base oil and asphalt in a mass ratio of (95 / 5) to (30 / 70). If the mass ratio is within this range, the compatibility of the rubber component (A) with the oil is further improved. The naphthenic base oil is preferably a hydrogenated naphthenic base oil, and more preferably a hydrogenated naphthenic base oil obtained by subjecting aromatic oils or naphthenic oils to a high degree of hydrorefining using a high-pressure, high-temperature hydrorefining production apparatus. Specifically, such hydrogenated naphthenic base oils are available as commercial products, such as SNH8, SNH46, SNH220, and SNH440 (all trademarks) manufactured by Sankyo Yuka Kogyo Co., Ltd. In addition, the asphalt to be mixed with the naphthenic base oil preferably contains an asphaltene component of 5 mass% or less, taking into consideration compatibility with the rubber components used and the effect of improving the cohesion of the rubber composition during kneading. The asphaltene component is quantified by composition analysis measured in accordance with the JPI method [Japan Petroleum Institute Standard JPI-5S-22-83 (established in 1983), standard name "Asphalt Composition Analysis Method by Column Chromatography"]. Such asphalt is preferably straight asphalt, and particularly preferably naphthenic straight asphalt. In addition, the asphalt has a kinetic viscosity of 300 mm at 120°C or more. 2 / sec or less is preferable. The method for mixing the asphalt is not particularly limited, but from the standpoint of ease of preparation and economic efficiency, a method in which the asphalt is dissolved in a naphthenic base oil (including extender oil and blending oil) is preferred. As the naphthenic oil containing asphalt, the product name "A / O Mix" manufactured by Sankyo Yuka Kogyo Co., Ltd. is preferred, which is obtained by mixing hydrogenated naphthenic base oil produced by a high-pressure, high-temperature hydrorefining unit with naphthenic straight asphalt containing 5 mass % or less asphaltene in a mass ratio of (63 / 37).

[0070] The content of the oil is preferably more than 0 parts by mass and not more than 15 parts by mass per 100 parts by mass of the rubber component (A), from the viewpoint of further improving the cohesion during kneading of the rubber composition and further improving the workability during kneading.

[0071] (liquid softener other than oil) The coating rubber composition for RFID tags of this embodiment may contain a liquid softener other than the oil. Here, the "liquid softener" is a compounding agent that is liquid at 25°C (room temperature) and has the effect of softening the rubber composition. The liquid softener is not particularly limited, and examples thereof include liquid polymers.

[0072] The liquid polymer is preferably a liquid diene polymer. 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, and liquid farnesene-butadiene copolymer. 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.

[0073] The content of the liquid softener other than the oil is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which it is applied, the 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 is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0074] (tackifier) The coating rubber composition for RFID tags of the present embodiment preferably contains a tackifier. When the rubber composition contains a tackifier, the adhesion of the rubber composition is improved, and the workability of the rubber composition during tire molding is improved. As the tackifier, various natural resins and synthetic resins can be used, and specifically, it is preferable to use rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins. These tackifiers may be used alone or in combination of two or more. When the rubber composition contains at least one selected from the group consisting of rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, and xylene-based resins, the adhesion of the rubber composition is further improved, and the workability of the rubber composition during tire molding is further improved. Among the resins, terpene-based resins and rosin-based resins are particularly preferable. Terpene-based resins and rosin-based resins are naturally derived sustainable resins, and therefore the environmental load can be further reduced.

[0075] Examples of the rosin-based resin include natural resin rosins such as gum rosin, tall oil rosin, and wood rosin contained in raw pine resin and tall oil. Examples of modified rosin, rosin derivatives, and modified rosin derivatives include polymerized rosin, partially hydrogenated rosin thereof, glycerin ester rosin, partially hydrogenated rosin thereof, and fully hydrogenated rosin thereof, pentaerythritol ester rosin, partially hydrogenated rosin thereof, and polymerized rosin, etc.

[0076] The terpene resin is a solid resin obtained by blending turpentine obtained at the same time when rosin is obtained from pine trees, or a polymerization component separated therefrom, and polymerizing it using a Friedel-Crafts catalyst, and examples of the terpene resin include β-pinene resin and α-pinene resin. The terpene resin also includes terpene-aromatic compound resin, and representative examples of the terpene-aromatic compound resin include terpene-phenol resin and styrene-terpene resin. The terpene-phenol resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts catalyst, or by further condensing with formalin. The styrene-terpene resin can be obtained by reacting styrene with terpenes using a Friedel-Crafts catalyst. The terpenes as the raw material are not particularly limited, and are preferably monoterpene hydrocarbons such as α-pinene and limonene, more preferably those containing α-pinene, and particularly preferably α-pinene.

[0077] Among the synthetic resins, the petroleum resin is obtained by polymerizing a mixture of cracked oil fractions containing unsaturated hydrocarbons such as olefins and diolefins, which are by-produced together with petrochemical basic raw materials such as ethylene and propylene, by thermal decomposition of naphtha in the petrochemical industry, with a Friedel-Crafts catalyst. Examples of the petroleum resin include aliphatic petroleum resins (hereinafter sometimes referred to as "C5 resins") obtained by (co)polymerizing a C5 fraction obtained by thermal decomposition of naphtha, aromatic petroleum resins (hereinafter sometimes referred to as "C9 resins") obtained by (co)polymerizing a C9 fraction obtained by thermal decomposition of naphtha, copolymerized petroleum resins (hereinafter sometimes referred to as "C5-C9 resins") obtained by copolymerizing the C5 fraction and the C9 fraction, alicyclic compound-based petroleum resins such as hydrogenated and dicyclopentadiene-based petroleum resins, and styrene-based resins such as copolymers of styrene, substituted styrene, or styrene and other monomers.

[0078] The C5 fraction obtained by thermal cracking of naphtha usually includes 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. In addition, aromatic petroleum resins obtained by (co)polymerizing the C9 fraction are resins obtained by polymerizing aromatics having 9 carbon atoms, with vinyltoluene and indene as the main monomers. Specific examples of the C9 fraction obtained by thermal cracking of naphtha include styrene homologues such as α-methylstyrene, β-methylstyrene, and γ-methylstyrene, and indene homologues such as indene and coumarone. Trade names include Petrozin manufactured by Mitsui Petrochemicals, Petrite manufactured by Mikuni Chemicals, Neopolymer manufactured by Nippon Petrochemicals, and Petcol manufactured by Toyo Soda.

[0079] Furthermore, from the viewpoint of workability, modified petroleum resins obtained by modifying petroleum resins made from the C9 fraction can be preferably used. Examples of the modified petroleum resins include C9 petroleum resins modified with unsaturated alicyclic compounds, C9 petroleum resins modified with compounds having hydroxyl groups, and C9 petroleum resins modified with unsaturated carboxylic acid compounds.

[0080] Preferred unsaturated alicyclic compounds include cyclopentadiene and methylcyclopentadiene. In addition, the Diels-Alder reaction product of an alkylcyclopentadiene is also preferred as the unsaturated alicyclic compound, and examples of the Diels-Alder reaction product of an alkylcyclopentadiene include dicyclopentadiene, cyclopentadiene / methylcyclopentadiene co-dimerization product, and tricyclopentadiene. Dicyclopentadiene is particularly preferred as the unsaturated alicyclic compound. Dicyclopentadiene-modified C9 petroleum resin can be obtained by thermal polymerization or the like in the presence of both dicyclopentadiene and a C9 fraction. An example of the dicyclopentadiene-modified C9 petroleum resin is Neopolymer 130S (manufactured by Nippon Petrochemical Co., Ltd.).

[0081] Examples of the compound having a hydroxyl group include alcohol compounds and phenol compounds. Specific examples of the alcohol compound include alcohol compounds having a double bond such as allyl alcohol and 2-butene-1,4-diol. Examples of the phenol compound include alkylphenols such as phenol, cresol, xylenol, p-tert-butylphenol, p-octylphenol, and p-nonylphenol. These compounds having a hydroxyl group may be used alone or in combination. In addition, C9-based petroleum resins having a hydroxyl group can be produced by a method of thermally polymerizing a (meth)acrylic acid alkyl ester or the like together with a petroleum fraction to introduce an ester group into the petroleum resin and then reducing the ester group, or a method of leaving or introducing a double bond into the petroleum resin and then hydrating the double bond, or the like. As the C9-based petroleum resin having a hydroxyl group, those obtained by various methods as described above can be used, but from the viewpoints of performance and production, it is preferable to use phenol-modified petroleum resins, etc. The phenol-modified petroleum resins are obtained by cationic polymerization of a C9 fraction in the presence of phenol, and are easy to modify and low-cost. An example of the phenol-modified C9 petroleum resin is Neopolymer E-130 (manufactured by Nippon Petrochemical Co., Ltd.).

[0082] Furthermore, the C9 petroleum resin modified with the unsaturated carboxylic acid compound can be obtained by modifying the C9 petroleum resin with an ethylenically unsaturated carboxylic acid. Representative examples of such ethylenically unsaturated carboxylic acids include maleic acid (anhydride), fumaric acid, itaconic acid, tetrahydrophthalic acid (anhydride), (meth)acrylic acid, and citraconic acid. The unsaturated carboxylic acid-modified C9 petroleum resin can be obtained by thermally polymerizing a C9 petroleum resin and an ethylenically unsaturated carboxylic acid. In the present invention, maleic acid-modified C9 petroleum resin is preferred. An example of the unsaturated carboxylic acid-modified C9 petroleum resin is Neopolymer 160 (manufactured by Nippon Petrochemical Co., Ltd.).

[0083] Also, a copolymer resin of C5 fraction and C9 fraction obtained by thermal cracking of naphtha can be suitably used. Here, the C9 fraction is not particularly limited, but is preferably a C9 fraction obtained by thermal cracking of naphtha. Specifically, TS30, TS30-DL, TS35, TS35-DL, etc. of the Struktol series manufactured by SCHILL & SEILACHER can be mentioned.

[0084] Among the synthetic resins, examples of the phenolic resins include alkylphenol formaldehyde resins and their rosin-modified products, alkylphenol acetylene resins, modified alkylphenol resins, terpene phenol resins, and the like. Specific examples include a novolac-type alkylphenol resin, Hitanol 1502 (manufactured by Hitachi Chemical Co., Ltd.), and a p-tert-butylphenol acetylene resin, Cholecin (manufactured by BASF).

[0085] In the synthetic resin, the coal-based resin may be a coumarone-indene resin, etc., and in the synthetic resin, the xylene-based resin may be a xylene-formaldehyde resin, etc. In addition, polybutene may also be used as a resin having tackifying properties.

[0086] The resin may be hydrogenated, i.e., may be a hydrogenated resin (hydrogenated resin). In addition, the resin may be modified to introduce a functional group that interacts with a filler such as carbon black or silica. Examples of the functional group include an amino group, an amide group, an isocyanate group, an imino group, an imidazole group, a urea group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, an ether group, a carbonyl group, an oxycarbonyl group, a silyl group, an alkoxysilyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, and a thiocarbonyl group.

[0087] The softening point of the resin is preferably 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. From the viewpoint of processability, the softening point of the resin is preferably 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 tackifier (resin) is the temperature at which the ball drops when the softening point as defined in JIS K 6220-1:2015 (ISO 28641:2010) is measured using a ring and ball softening point tester.

[0088] As the tackifier, commercially available products can be used. Examples of commercially available tackifiers that can be used include products from ENEOS Corporation, Arakawa Chemical Industries, Ltd., ExxonMobil Corporation, Clayton, Yasuhara Chemical Co., Ltd., Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Clayton Polymers, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., and Taoka Chemical Co., Ltd.

[0089] From the viewpoint of further improving the adhesion of the rubber composition and further improving workability during tire molding, the content of the tackifier is preferably more than 0 part by mass and not more than 15 parts by mass per 100 parts by mass of the rubber component (A).

[0090] (Carbon Black) The coating rubber composition for RFID tags of the present embodiment may or may not contain carbon black as a filler other than silica. As the carbon black, carbon black derived from plants and carbon black obtained by recycling (i.e., recycled carbon black) are particularly preferred. Examples of carbon black derived from plants include those derived from castor oil and pine oil. Examples of recycled carbon black include carbon black obtained by decomposition (particularly pyrolysis) of crosslinked rubber products such as used tires, and carbon black obtained from waste oil.

[0091] The crosslinked rubber products used for the decomposition may be grouped according to the type of rubber component previously blended, and then the decomposition step may be performed for each group. Alternatively, the crosslinked rubber products may be grouped according to the type of filler previously blended (e.g., the type of carbon black, the type of silica, the mixing ratio of carbon black and silica, etc.), and then the decomposition step may be performed for each group. Furthermore, the crosslinked rubber products may be grouped according to the type of rubber component and the type of filler, and then the decomposition step may be performed for each group. When the decomposition step is performed for each group in this way, recycled carbon black with more uniform physical properties is obtained, and therefore, when the recycled carbon black is blended again with the rubber component, a rubber composition with better performance is obtained.

[0092] In addition, when the crosslinked rubber product used for the decomposition is derived from a tire, the tire may be grouped in advance by type (for example, for passenger cars, for trucks and buses, for large vehicles such as off-road vehicles, for aircraft, for agricultural vehicles, etc.), and then the decomposition step may be performed for each group. In addition, the tire may be grouped in advance by tire components (for example, tread rubber, sidewall rubber, bead rubber, steel cord coated rubber, organic fiber coated rubber, pad rubber, cushion rubber, etc.), and then the decomposition step may be performed for each group. Furthermore, the tire may be grouped by type and by tire components, and then the decomposition step may be performed for each group. When the decomposition step is performed for each group in this way, recycled carbon black with more uniform physical properties is obtained, so that when it is blended again into the rubber component, a rubber composition with better performance is obtained.

[0093] The grade of the carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks can be used, and examples of the commercially available carbon blacks include products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Birla Carbon Co., Ltd. These carbon blacks may be used alone or in combination of two or more.

[0094] 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 to which it is applied, the tire components, the target performance, etc. For example, the nitrogen adsorption specific surface area (N2SA) of carbon black is 20 m 2 / g or more is preferable, and 50m 2 / g or more is more preferable, and 70m 2 / g or more is more preferable, and 90m 2 / g or more is more preferable, and 200m 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 / g or less is more preferable. In this specification, the nitrogen adsorption specific surface area (N2SA) of carbon black is determined in accordance with JIS K 6217-2:2017 (ISO 4652:2012).

[0095] The content of the carbon black is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 0 part by mass (i.e., no carbon black) per 100 parts by mass of the rubber component (A). When the content of the carbon black is 15 parts by mass or less per 100 parts by mass of the rubber component (A), the relative dielectric constant of the rubber composition decreases and the communication distance of the RFID tag increases, and when the content is 0 parts by mass (i.e., no carbon black is included), the relative dielectric constant of the rubber composition decreases further and the communication distance of the RFID tag increases further.

[0096] The content of silica (B) in the total content of silica (B) and carbon black is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass. When the content of silica (B) in the total content of silica (B) and carbon black is 80 to 100% by mass, the crack resistance and elastic modulus of the rubber composition can be improved, while the relative dielectric constant of the rubber composition can be reduced, and the communication distance of the RFID tag can be further extended.

[0097] (rubber powder) The coating rubber composition for RFID tags of the present embodiment may contain rubber powder. The rubber powder may be obtained by crushing used rubber products such as used tires, and removing reinforcing materials such as steel materials and fibers, dust, glass, sand, stones, etc., as desired, or by preparing a new vulcanized rubber composition to produce rubber powder and crushing it. For example, rubber powder can be obtained from vulcanized rubber by the method described in "Rubber Chemistry And Technology". In the process of crushing vulcanized rubber to obtain rubber powder, mechanical treatment or low-temperature treatment may be used. For example, in the mechanical treatment, various crushing devices such as a cracker mill and a granulator can be used to mechanically crush the vulcanized rubber into fine particles. In the low-temperature treatment, the finely chopped vulcanized rubber is frozen at a very low temperature and then crushed into fine particles. In addition, a magnetic separator or the like can be used to remove steel materials, and an air separator or the like can be used to remove fibers. As the rubber powder, a commercially available product can be used, and examples of the commercially available rubber powder include products from Global Corporation or Nantong Huili Rubber Corporation. From the viewpoint of reducing the environmental load, it is preferable to use rubber powder obtained by crushing used rubber products such as used tires. The rubber powder may be used alone or in combination of two or more kinds.

[0098] The composition of the rubber powder is not particularly limited, and depends on the composition of vulcanized rubber such as used rubber products (used tires) that serve as a raw material. 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 (A), carbon black, silica (B), etc. that may be contained in the coating rubber composition for RFID tags of the present embodiment described above.

[0099] The rubber powder has a volume average particle size of preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 200 μm or less, and even more preferably 100 μm or less. The smaller the volume average particle size of the rubber powder, the better, and there is no particular lower limit. In this specification, the volume average particle size is measured by a laser diffraction particle size distribution measuring device, for example, "CAPA500" manufactured by Horiba, Ltd.

[0100] The rubber powder has a 60 mesh sieve residue of preferably less than 1 mass%, more preferably 0.5 mass% or less, and even more preferably 0.1 mass% or less, with no particular lower limit. Also, the rubber powder has an 80 mesh sieve residue of preferably less than 10 mass%, more preferably 1 mass% or less, and even more preferably 0.5 mass% or less, with no particular lower limit. In this specification, the sieve residue is measured in accordance with ASTM D5644-01.

[0101] The rubber powder has an acetone extractable content of preferably 12% by mass or less, more preferably 11% by mass or less, and even more preferably 10% by mass or less, and preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more. In this specification, the acetone extractables in the rubber powder refer to the acetone extractables (%) determined by the acetone extraction method in accordance with JIS K6350.

[0102] The content of the rubber powder is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber component (A) is applied, 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, and even more preferably 3 parts by mass or more, and is 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, relative to 100 parts by mass of the rubber component (A).

[0103] (Anti-aging agent) The coating rubber composition for RFID tags of this embodiment may contain an antioxidant, such as 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), and 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline. As the antiaging agent, commercially available products can be used, and examples of the commercially available antiaging agent include products from Ouchi Shinko Chemical Industry Co., Ltd., Sumitomo Chemical Co., Ltd., Seiko Chemical Co., Ltd., Flexis Co., Ltd., etc. These antiaging agents may be used alone or in combination of two or more.

[0104] The content of the antiaging agent is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the antiaging agent is applied, the target performance, etc. For example, the content of the antiaging agent is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, and is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0105] (wax) The coating rubber composition for RFID tags of this embodiment may contain wax. Examples of the wax include natural waxes such as vegetable wax and animal wax; petroleum waxes such as paraffin wax and microcrystalline wax; and synthetic waxes such as ethylene polymers and propylene polymers. Commercially available products can be used as the wax, and examples of the commercially available wax products that can be used include products from Seiko Chemical Co., Ltd., Nippon Seiro Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and the like. These waxes may be used alone or in combination of two or more.

[0106] The content of the wax is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, 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 is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0107] (Stearic acid) The coating rubber composition for RFID tags of the present embodiment may contain stearic acid. Commercially available stearic acid may be used, and examples of the commercially available stearic acid include products from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Corp., Chiba Fatty Acid Corp., etc. These commercially available stearic acid products may be used alone or in combination of two or more.

[0108] The content of the stearic acid is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, the target performance, etc. For example, the content of the stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0109] (Zinc Oxide) The coating rubber composition for RFID tags of this embodiment may contain zinc oxide (zinc white). The zinc oxide is preferably obtained not only from zinc ingot but also from recycled zinc or zinc dross (i.e., obtained by recycling). Commercially available zinc oxide can be used, and examples of the commercially available zinc oxide include products from Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., and the like. These commercially available zinc oxide products may be used alone or in combination of two or more.

[0110] The content of the zinc oxide is not particularly limited, and can be appropriately adjusted depending on, for example, the tire category to which the rubber composition is applied, the target performance, etc. For example, the content of the zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, relative to 100 parts by mass of the rubber component (A).

[0111] (others) In addition to the above-mentioned components, the coating rubber composition for RFID tags of this embodiment may further contain various additives commonly used in the tire industry, such as fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica; organic peroxides; etc. The content of these additives is not particularly limited and can be appropriately adjusted depending on, for example, the tire category to which the composition is applied, the target performance, etc., and is preferably in the range of 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component (A).

[0112] (Method of manufacturing rubber composition) The method for producing the coating rubber composition for RFID tags of the present embodiment is not particularly limited, but for example, the composition can be produced by blending the rubber component (A) with plant-derived silica (B1) and various components appropriately selected as necessary, and kneading, heating, extruding, etc. The obtained rubber composition can be vulcanized to produce a vulcanized rubber.

[0113] The conditions for the kneading are not particularly limited, and various conditions such as the input volume of the kneading device, the rotation speed of the rotor, the ram pressure, the kneading temperature, the kneading time, the type of the kneading device, etc. can be appropriately selected depending on the purpose. Examples of the kneading device include a Banbury mixer, an intermix, a kneader, a roll, etc. that are usually used for kneading rubber compositions.

[0114] The conditions of the heat-in are not particularly limited, and various conditions such as the heat-in temperature, heat-in time, heat-in device, etc. can be appropriately selected depending on the purpose. Examples of the heat-in device include a heat-in roller machine usually used for heat-in of a rubber composition.

[0115] The extrusion conditions are not particularly limited, and various conditions such as extrusion time, extrusion speed, extrusion device, and extrusion temperature can be appropriately selected depending on the purpose. Examples of the extrusion device include an extruder that is usually used for extruding a rubber composition. The extrusion temperature can be appropriately determined.

[0116] The vulcanization apparatus, method, conditions, etc. are not particularly limited and can be appropriately selected according to the purpose. As the vulcanization apparatus, a molding vulcanizer using a mold used for vulcanizing a rubber composition can be mentioned. As the vulcanization condition, the temperature is, for example, about 100 to 190°C.

[0117] <Tires> The tire of the present embodiment is characterized by including an RFID tag coated with the above-mentioned coating rubber composition for RFID tags. Since the tire of the present embodiment includes an RFID tag coated with the above-mentioned coating rubber composition for RFID tags, the ratio of sustainable materials is improved and communication performance, etc. is not impaired.

[0118] The RFID tag is generally made of materials such as metal and resin. For example, in one embodiment, the RFID tag includes an electronic device part and an antenna part connected to the electronic device part, and the housing (or package) of the electronic device part is made of resin and the antenna part is made of metal. When the RFID tag is coated with the coating rubber composition for RFID tags of the present embodiment, an adhesive such as "CHEMLOC" (registered trademark) manufactured by LORD Corporation is applied to the RFID tag in advance, so that the adhesion between the RFID tag and the coating rubber can be sufficiently ensured.

[0119] In addition, since the RFID tag is harder than the rubber members in the tire, in order to suppress the concentration of stress on the RFID tag, it is preferable that the coating rubber of the RFID tag has a higher elastic modulus (i.e., is harder) than the adjacent rubber members (for example, the side rubber, stiffener, etc., which will be described later). The above-mentioned coating rubber composition for RFID tags has a high elastic modulus and is hard, and therefore has the effect of suppressing the concentration of stress on the RFID tag.

[0120] The RFID tag is preferably disposed in a portion of the tire that is relatively less susceptible to distortion during running. In one embodiment, the RFID tag coated with the above-mentioned coating rubber composition for RFID tags is preferably disposed between a stiffener disposed on the radially outer side of a bead core embedded in a bead portion of the tire and a side rubber located on the tire widthwise outer side of a carcass in a side portion of the tire. In this embodiment, it is further preferable to dispose the RFID tag coated with the coating rubber composition for RFID tags in a portion radially inward of the maximum width portion of the tire.

[0121] FIG. 1 is a cross-sectional view of one embodiment of a tire of the present invention. The tire 1 shown in FIG. 1 has a pair of bead portions 2 and a pair of side portions 3, and a tread portion 4 connected to both side portions 3. The tire 1 is equipped with a carcass 5 extending in a toroidal shape between the pair of bead portions 2 to reinforce these portions 2, 3, 4, a belt 6 arranged on the radially outer side of a crown portion of the carcass 5, and stiffeners 8 arranged on the radially outer side of ring-shaped bead cores 7 respectively embedded in the bead portions 2. The stiffener 8 is made up of a hard stiffener 8a having a relatively high rigidity adjacent to the bead core 7 on the outer side in the tire radial direction, and a soft stiffener 8b having a relatively low rigidity adjacent to the hard stiffener 8a on the outer side in the tire radial direction. Further, a side rubber 9 is disposed on the outer side of the carcass 5 of the side portion 3 in the tire width direction.

[0122] In the tire 1 of the illustrated example, the carcass 5 has a main body portion 5a extending toroidally between a pair of bead cores 7, and a turn-up portion 5b wound up radially outward from the inside to the outside in the tire width direction around each bead core 7. The structure and number of plies of the carcass 5 are not limited to this. The stiffener 8 is disposed between the main body portion 5a of the carcass 5 and the turn-up portion 5b. A wire chafer 10 is disposed on the outer surface side of the turn-up portion 5b of the carcass 5, and the wire chafer 10 further extends along the outer side of the stiffener 8 in the tire width direction.

[0123] An RFID tag 12 covered with a coating rubber 11 is disposed in a region radially inward of the maximum width portion of the tire, between the side rubber 9 and the soft stiffener 8b, and radially outward of the wire chafer 10. The coating rubber 11 uses the above-mentioned coating rubber composition for RFID tags. The RFID tag 12 coated with the coating rubber 11 (RFID tag-rubber composite) can be produced, for example, by preparing two rubber sheets made of the above-mentioned coating rubber composition for RFID tags and sandwiching the RFID tag 12 between the rubber sheets. The tire of this embodiment can be produced by laminating the RFID tag-rubber composite together with other rubber members to form a green tire, and vulcanizing the green tire.

[0124] As described above, the rubber composition applied to the coating rubber 11 has an increased ratio of sustainable materials, and therefore the tire 1 shown in FIG. 1 has an increased ratio of sustainable materials. Furthermore, since the rubber composition applied to the coating rubber 11 has good communication performance as described above, the tire 1 shown in FIG. 1 has a long communication distance and excellent communication performance. Furthermore, as described above, the rubber composition applied to the coating rubber 11 has a sufficient balance of crack resistance, adhesion to adjacent rubber members, and elastic modulus, so that the tire 1 shown in FIG. 1 has excellent durability.

[0125] The tire of this embodiment can be manufactured by a normal method using the above-mentioned rubber composition. For example, the tire of this embodiment may be obtained by molding an unvulcanized rubber composition and then vulcanizing it, or by molding a semi-vulcanized rubber that has been subjected to a pre-vulcanization process or the like and then further vulcanizing it, depending on the type of tire to be applied. The tire of this embodiment is preferably a pneumatic tire, and the gas to be filled in the pneumatic tire may be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium. EXAMPLES

[0126] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0127] <Preparation of Rubber Composition of Comparative Example 1> According to the compounding recipe shown in Table 1, the compounding ingredients except for the vulcanization accelerator, vulcanizing agent, and other Pro chemicals were filled to a filling rate of 55% to 65% using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., and kneaded at a rotation speed of 80 rpm until the temperature reached 160°C or 4 minutes had elapsed. Next, the vulcanization accelerator, vulcanizing agent, and other Pro chemicals were added to the kneaded product in the compounding amounts shown in Table 1, and the product was kneaded using an open roll at 80°C for 2 minutes to obtain an unvulcanized rubber composition. The total mass ratio of materials derived from biological resources (biomass resources) and materials derived from recycled resources (recycled resources) was calculated for the rubber composition to calculate the sustainable material ratio.

[0128] <Preparation of Rubber Composition of Example 1> According to the compounding recipe shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., the compounding ingredients except for the vulcanization accelerator, vulcanizing agent, and other Pro chemicals are filled so that the filling rate is 55% to 65%, and the mixture is kneaded at a rotation speed of 80 rpm until the temperature reaches 160°C or 4 minutes have passed. Next, the vulcanization accelerator, vulcanizing agent, and other Pro chemicals are added to the kneaded product in the compounding amounts shown in Table 1, and the mixture is kneaded using an open roll at 80°C for 2 minutes to obtain an unvulcanized rubber composition. The total mass ratio of materials derived from biological resources (biomass resources) and materials derived from recycled resources (recycled resources) is calculated for the rubber composition, and the sustainable material ratio is calculated.

[0129] [Table 1]

[0130] *1 Natural rubber: RSS#3 *2 Mineral-derived silica: Tosoh Silica Corporation, product name "Nipsil AQ" *3 Plant-derived silica: rice husk silica *4 Silane coupling agent: Bis(3-triethoxysilylpropyl) disulfide (average sulfur chain length: 2.35), Evonik silane coupling agent, product name "Si75" *5 Tackifier: SI Group RIBECOURT SAS, product name "R7510PJ" *6 Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela CZ-G" *7 Insoluble sulfur: Sulfur containing insoluble sulfur, manufactured by Sanshin Chemical Industry Co., Ltd., product name "Sanfer Ex", the ratio of insoluble sulfur in sulfur = 90% by mass

[0131] From Table 1, it can be seen that the rubber compositions of the examples according to the present invention have an improved ratio of sustainable materials, and by applying them to tires, the ratio of sustainable materials in the tires can be improved.

[0132] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 13: Take concrete measures against climate change." [Explanation of symbols]

[0133] 1: Tires 2: Bead section 3: Side section 4: Tread section 5: Carcass 5a: Main body of carcass 5b: Carcass fold-back 6: Belt 7: Bead core 8: Stiffener 8a: Hard stiffener 8b: Soft stiffener 9: Side rubber 10: Wire chafer 11:Coating rubber 12: RFID tags

Claims

1. The rubber composition includes a rubber component (A) and a silica (B), The silica (B) contains plant-derived silica (B1), A coating rubber composition for RFID tags, characterized in that the content of the silica (B) is 45 parts by mass or more per 100 parts by mass of the rubber component (A).

2. The coating rubber composition for RFID tags according to claim 1, further comprising a silane coupling agent (C).

3. 3. The coating rubber composition for RFID tags according to claim 2, wherein the content of the silane coupling agent (C) is 5 to 20 mass % of the content of the silica (B).

4. 2. The coating rubber composition for RFID tags according to claim 1, wherein the content of the silica (B) is 45 to 90 parts by mass based on 100 parts by mass of the rubber component (A).

5. 2. The coating rubber composition for RFID tags according to claim 1, wherein the plant-derived silica (B1) is silica derived from a grass family plant.

6. The coating rubber composition for RFID tags according to claim 5, wherein the plant-derived silica (B1) is silica derived from rice husks.

7. 2. The coating rubber composition for RFID tags according to claim 1, wherein the content of carbon black is 15 parts by mass or less based on 100 parts by mass of the rubber component (A).

8. 2. The coating rubber composition for RFID tags according to claim 1, wherein a content ratio of the silica (B) in a total content of the silica (B) and the carbon black is 80 to 100 mass %.

9. A tire comprising an RFID tag coated with the coating rubber composition for RFID tags according to claim 1.

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