Repair sheet and tire repair method

Abstract

The present invention makes it possible to provide a repairing sheet and a tire repairing method with which a tire can be processed with reduced time and effort. This repairing sheet to be attached to a tire region includes a retaining layer capable of retaining an additive to be supplied to the inner part of the tire region, wherein the retaining layer has a breaking strength of at least 0.5 MPa and an elongation at break of at least 5%.

Description

[Technical field]

[0001] The present disclosure relates to a repair sheet and a method for repairing a tire. [Background technology]

[0002] Conventionally, for tires whose tire rubber has reached the end of its useful life, for example, for tires whose tread portion has reached the end of its useful life, a processing method has been known in which the old tread portion is removed and then the tread portion is replaced with new tread rubber (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-114781 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional processing methods require operations such as removing and attaching the tread portion, and therefore such processing operations require a lot of work.

[0005] The present disclosure seeks to provide a repair sheet and method for repairing a tire. [Means for solving the problem]

[0006] The present disclosure relates to a repair sheet for application to a tire portion, A retaining layer capable of retaining an additive for supplying to an interior of a tire portion, The repair sheet has a breaking strength of 0.5 MPa or more and a breaking elongation of 5% or more in the retaining layer. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a repair sheet that enables processing of a tire with reduced effort, and a tire repair method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The repair sheet according to the present disclosure is a repair sheet for application to a tire part, and is provided with a retaining layer capable of retaining an additive to be supplied to the inside of the tire part, the retaining layer having a breaking strength of 0.5 MPa or more and a breaking elongation of 5% or more.

[0009] According to this configuration, since it has a breaking strength of a predetermined level or more, it is difficult to break during use, and since it has a breaking elongation of a predetermined level or more, it is easy to follow the tire part during use. Therefore, it is easy to handle. Therefore, it is possible to process the tire with less effort. In addition, the supply amount of the additive can be adjusted by the amount of the additive held in the repair sheet, in addition to the repair time during which the repair sheet holding the additive is brought into contact with the tire. Note that the physical properties of the breaking strength of the retaining layer being 0.5 MPa or more and the breaking elongation being 5% or more are values ​​in a state in which the additive is not held in the retaining layer. In addition, "repair" in this disclosure does not only refer to processing of tires for improving or maintaining the performance of used tires, but also includes processing of tires for improving or modifying the performance of new tires.

[0010] The support layer is preferably made of a material containing at least one selected from the group consisting of a thermoplastic elastomer, a resin, and a crosslinked rubber, because this makes it easier to obtain the desired support layer according to the present disclosure.

[0011] The thickness of the support layer is preferably 100 mm or less, because if it is too thick, it becomes difficult to handle.

[0012] It is preferable that the repair sheet further comprises a support layer that supports the retaining layer, because by further comprising a support layer, the repair sheet becomes easier to handle.

[0013] The repair sheet of the present disclosure is used for processing tires with additives held in the holding layer. The additives preferably include at least one selected from the group consisting of a plasticizer, an antioxidant, and a vulcanization accelerator.

[0014] Another embodiment of the present disclosure is a method for repairing a tire, the method including the steps of attaching the repair sheet to a tire portion and supplying the additive to an interior of the tire portion.

[0015] When applied to the tread portion of a tire, it is preferable that the longitudinal length of the retaining layer is equal to or less than the tire width plus 10 mm, the lateral length is equal to or less than the tire circumference plus 10 mm, and the thickness is equal to or less than 110 mm.

[0016] [Definition] (Tire area) A tire part is a term that specifies the position on a surface of a tire component that constitutes the surface, including the outer surface or inner surface of the tire, and is, for example, a tread portion, a sidewall portion, a clinch portion, a wing portion, an inner liner portion, etc., but is not limited to these, as long as the position of the tire component on the surface can be specified.

[0017] [Measurement method] (Additive content inside the tire tread) The additive content is determined in accordance with JIS K 6229 by immersing samples cut from the tread surface of each tire in acetone for 24 hours to extract the soluble components, measuring the mass of each sample before and after extraction, and calculating the amount of extractables according to the following formula. Extractables (%) = {(mass of sample before extraction - mass of sample after extraction)} / (mass of sample before extraction)}×100

[0018] (Tire tread hardness) The hardness is measured in accordance with JIS K 6253 by pressing a type A durometer against the sample at 23°C.

[0019] (Breaking strength and elongation at break of the retaining layer) The breaking strength TB (MPa) and breaking elongation EB (%) are measured by conducting a tensile test on a 1 mm thick No. 7 dumbbell shaped test piece in accordance with JIS K 6251 "Vulcanized rubber and thermoplastic rubber - Determination of tensile test characteristics" at an atmosphere of 23°C and a tensile speed of 3.3 mm / sec.

[0020] (Ozone resistance of tire tread) The ozone resistance is evaluated by preparing a test piece of a predetermined size from the surface of the tread portion and performing a dynamic ozone deterioration test on the test piece in accordance with JIS K 6259 "Vulcanized rubber and thermoplastic rubber - Determination of ozone resistance". In detail, the test piece is subjected to a test of applying a reciprocating motion of a frequency of 0.5±0.025Hz for 48 hours under the conditions of an ozone concentration of 50±5pphm, a test temperature of 40°C, and a tensile strain of 10±2%, and the state of cracks (presence or absence of cracks, number of cracks, length of cracks, etc.) generated on the test piece after the test is observed. The evaluation method uses the method described in JIS K 6259 (Method A: Crack state observation method). Specifically, the number of cracks of 0.05mm or more confirmed after the test is multiplied by the average length of cracks of 0.05mm or more to calculate a value indicating the degree of crack generation, and the reciprocal of the value is used as the evaluation value of the ozone resistance index.

[0021] (Weight average molecular weight of various materials used in repair sheets) The "weight average molecular weight" can be determined based on a measurement value obtained by gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation) in terms of standard polystyrene.

[0022] (Resin tensile strength) "Resin tensile strength (MPa)" can be determined as tensile strength (50 mm / min) according to ISO 527-1.

[0023] [Repair sheet] The repair sheet of the present disclosure will be described below.

[0024] <Retention layer> The retaining layer is capable of retaining an additive, and has a breaking strength of 0.5 MPa or more and a breaking elongation of 5% or more. These values ​​are the physical properties of the retaining layer in a state in which no additive is retained. It is preferable that the retaining layer in a state in which an additive is retained (the entire layer consisting of the retaining layer and the additive retained in the retaining layer) also satisfies these physical properties.

[0025] (Breaking strength) From the viewpoint of ensuring the strength during use, the breaking strength (MPa) of the retaining layer is preferably more than 0.5, more preferably more than 1.0, even more preferably more than 1.5, even more preferably more than 2.0, even more preferably 3.0 or more, even more preferably more than 5.0, even more preferably more than 10.0, even more preferably more than 15.0, even more preferably 17.0 or more. On the other hand, there is no particular upper limit from the viewpoint of ensuring the strength during use for the breaking strength (MPa), but the upper limit is usually less than about 40.0, or less than 35.0, or less than 30.0, or less than 25.0, or may be less than 20.0. This value is the physical property of the retaining layer in a state where no additive is retained. It is preferable that the retaining layer in a state where an additive is retained (the entire layer consisting of the retaining layer and the additive retained in the retaining layer) also satisfies this physical property.

[0026] (Elongation at break) From the viewpoint of ensuring the conformability during use, the breaking elongation (%) of the retaining layer is preferably more than 5, more preferably more than 10, more preferably more than 50, more preferably more than 100, more preferably more than 200, more preferably more than 230, more preferably more than 300, more preferably more than 400, more preferably more than 420, more preferably more than 500, and more preferably more than 600. On the other hand, there is no particular upper limit for the breaking elongation (%) from the viewpoint of ensuring the conformability during use, but the upper limit is usually less than about 1200, or less than 1100, or less than 1000, or less than 900, or may be less than 800. This value is the physical property of the retaining layer in a state where no additive is held. It is preferable that the retaining layer in a state where an additive is held (the entire layer consisting of the retaining layer and the additive held in the retaining layer) also satisfies this physical property.

[0027] (Size) From the viewpoint of ease of handling, the thickness of the retaining layer is preferably 100 mm or less, more preferably 80 mm or less, even more preferably 60 mm or less, and even more preferably 50 mm or less. On the other hand, the lower limit of the thickness is not particularly limited as long as it can retain the necessary amount of additive, but is usually preferably 0.5 mm or more, more preferably 0.8 mm or more, and even more preferably 1 mm or more. This value is the dimension of the retaining layer in a state where no additive is retained. It is preferable that the retaining layer in a state where an additive is retained (the entire layer consisting of the retaining layer and the additive retained in the retaining layer) also satisfies this dimension.

[0028] In the case of a repair sheet intended to be attached to the tread of a tire, the length of the retaining layer in the tire width direction (vertical) is preferably equal to or less than the tire width, and the length of the retaining layer in the tire circumferential direction (horizontal) is preferably equal to or less than the tire outer periphery.

[0029] (Additive retention) The ratio (mass%) of the mass of the additive to the total mass of the retention layer and the mass of the additive retained by the retention layer is preferably more than 0.1 mass%, more preferably more than 15 mass%, and even more preferably more than 25 mass%. On the other hand, there is no particular upper limit for the ratio (mass%), but it is usually less than 99.9 mass%, or less than 92 mass%, or less than 90 mass%.

[0030] In the case of a repair sheet intended to be attached to a tire tread, the thickness of the retaining layer retaining the additive is preferably 110 mm or less, more preferably 88 mm or less, even more preferably 66 mm or less, and even more preferably 55 mm or less. On the other hand, the lower limit of the thickness is not particularly limited, but is usually preferably 0.55 mm or more, more preferably 0.88 mm or more, and even more preferably 1.1 mm or more. In addition, the vertical length of the retaining layer is preferably equal to or less than the tire width plus 10 mm. In addition, the horizontal length of the retaining layer is preferably equal to or less than the tire circumference plus 10 mm.

[0031] <Material for retention layer> As described above, the material of the retaining layer is not particularly limited as long as it can retain the additive and has a predetermined breaking strength and elongation at break. Examples of such materials include thermoplastic elastomers, resins, and crosslinked rubbers. It is preferable to use one or more materials constituting the retaining layer. Note that, since a resin may be used as the material of the retaining layer or as the additive, hereinafter, the resin as the material of the retaining layer is referred to as the first resin, and the resin as the material of the additive is referred to as the second resin.

[0032] (Thermoplastic elastomer) The thermoplastic elastomer that is the material of the retaining layer is not limited as long as it can retain additives, and can form a retaining layer that can be deformed and attached to the shape of the tire while satisfying certain requirements such as breaking strength. Examples of the thermoplastic elastomer include styrene-based elastomers, polyurethane-based elastomers, and polyester-based elastomers. Among these, styrene-based elastomers are preferred. One or more types of thermoplastic elastomers can be used.

[0033] As the styrene-based elastomer, a thermoplastic elastomer containing a styrene block can be suitably used. The styrene block-containing thermoplastic elastomer has a polystyrene block as a hard segment and a soft segment. A typical soft segment is a diene block. Examples of the constituents of the diene block include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene, among which butadiene and isoprene are preferred. As the constituents of the diene block, one or more constituents can be used.

[0034] The styrene block-containing thermoplastic elastomer includes styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene-styrene block copolymer (SIBS), hydrogenated SBS, hydrogenated SIS, and hydrogenated SIBS. Hydrogenated SBS includes styrene-ethylene-butylene-styrene block copolymer (SEBS) and styrene-butadiene-butylene-styrene block copolymer (SBBS). Hydrogenated SIS includes styrene-ethylene-propylene-styrene block copolymer (SEPS). Among these, SEBS is preferred.

[0035] From the viewpoint of obtaining the retaining layer of the present disclosure, the content of the styrene component in the styrene block-containing thermoplastic elastomer is preferably more than 10 mass%, more preferably more than 12 mass%, and even more preferably more than 15 mass%. From the same viewpoint, this content is preferably less than 50 mass%, more preferably less than 47 mass%, and even more preferably less than 45 mass%.

[0036] The polyurethane elastomer may be a thermoplastic elastomer having a plurality of urethane bonds in the main chain of the molecule. The polyurethane is preferably obtained by reacting a polyisocyanate component with a polyol component. The polyisocyanate component may be diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), or the like.

[0037] As the polyester-based thermoplastic elastomer, one using an olefin-based elastomer as a soft segment and polyethylene terephthalate, polybutylene terephthalate, etc. as a hard segment is preferably used. As the olefin-based elastomer, there can be mentioned one obtained by homopolymerizing one type selected from the group consisting of linear alkenes, branched alkenes, and polyvinyl acetates having 1 to 8 carbon atoms, or copolymerizing two or more types, and specific examples thereof include ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, linear low-density polyethylenes, etc.

[0038] (First resin) The first resin, which is the material of the retaining layer, is not limited as long as it can retain the additive, and can form a retaining layer that can be deformed and attached along the shape of the tire while satisfying predetermined requirements such as breaking strength. As such a first resin, plastics or those generally used in the tire industry can be used. The first resin is solid at 25°C. The softening temperature of the first resin is preferably above 60°C, more preferably above 70°C, and even more preferably above 80°C. The softening temperature of the first resin is a value (so-called Vicat softening temperature) measured by the A50 method of JIS K7206 (test load: 10N, temperature rise rate: 50°C / h). Examples of the first resin include alkylphenol resins, coumarone-indene resins, terpene resins, styrene resins, rosin resins, acrylic resins, and dicyclopentadiene resins (DCPD resins). Among these, styrene resins are preferred. Examples of the styrene-based resin include a resin which is a homopolymer of α-methylstyrene or styrene, and a resin which is a copolymer of at least one of α-methylstyrene and styrene with butadiene, and among these, a styrene-butadiene copolymer resin is preferable. The first resin may be used alone or in combination of two or more kinds.

[0039] Examples of the alkylphenol resins that can be used include those manufactured by BASF and Taoka Chemical Co., Ltd. Examples of the coumarone-indene resins that can be used include those manufactured by Nippon Steel Chemical & Material Co., Ltd. and ENEOS Co., Ltd. Examples of the terpene resins that can be used include those manufactured by Clayton Polymers and Yasuhara Chemical Co., Ltd. Examples of the styrene resins that can be used include those manufactured by Asahi Kasei Co., Ltd. and Clayton Polymers. Examples of the rosin resins that can be used include those manufactured by Harima Chemical Co., Ltd. and Arakawa Chemical Co., Ltd.

[0040] From the viewpoint of the effects of the present disclosure, the tensile strength (MPa) of the first resin is preferably 5 or more, more preferably 10 or more, and even more preferably 15 or more. There is no particular upper limit to the tensile strength, but it is usually about 50 or less, or about 40 or less. The tensile strength (MPa) of the first resin is measured by the method for measuring the tensile strength of resins.

[0041] (Crosslinked rubber) The crosslinked rubber that is the material of the retaining layer is not limited as long as it can retain additives, and can form a retaining layer that can be deformed and attached to the shape of the tire while satisfying predetermined requirements such as breaking strength. Here, the crosslinked rubber refers to rubber in which chain-like rubber molecules are crosslinked to each other to form a three-dimensional network structure that does not cause plastic deformation.

[0042] As the rubber component constituting the crosslinked rubber, a crosslinkable rubber component generally used in the tire industry can be used, and examples of such rubber components include natural rubber (NR), isoprene-based rubbers such as isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene-butadiene copolymer rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, hydrin rubber, etc. The rubber components may be used alone or in combination of two or more.

[0043] More specifically, for example, the NR is not particularly limited and may be one commonly used in the tire industry, and SIR20, RSS#3, TSR20, etc. may be used. The SBR is not particularly limited and may be one commonly used in the tire industry, and either emulsion-polymerized styrene-butadiene rubber (E-SBR) or solution-polymerized styrene-butadiene rubber (S-SBR) may be used, and may be manufactured and sold by JSR Corporation, Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., Asahi Kasei Corporation, ZS Elastomers Co., Ltd., etc. The BR is not particularly limited and may be one commonly used in the tire industry, and may be one commonly used in the tire industry, and may be manufactured and sold by JSR Corporation, Zeon Corporation, Ube Industries, Ltd., etc.

[0044] <Additives> The additive is an additive that is added to the rubber composition constituting the tire and has a property of permeating into the rubber composition and softening the rubber composition by itself, or, if the additive does not have a property of permeating into the rubber composition by itself, is an additive that is used by mixing with an additive that has a property of permeating into the rubber composition and softening the rubber composition. The additive preferably includes at least one selected from the group consisting of a plasticizer, an antioxidant, and a vulcanization accelerator. In the present disclosure, the additive is supplied to the inside of the rubber composition constituting the tire part, and permeates into the inside of the tire part preferably by 0.1 mm or more, more preferably by 1 mm or more, and even more preferably by 2 mm or more.

[0045] (Plasticizer) Examples of the plasticizer include oil, resin (second resin), liquid rubber, and ester-based plasticizers. Of these, oil, second resin, and ester-based plasticizers are preferred. As an additive, it is preferred to use, or combine with, these plasticizers that are liquid at room temperature (25°C). The plasticizers may be used alone or in combination of two or more.

[0046] <Oil> Examples of oils include mineral oils, vegetable oils (or fats and oils), and mixtures thereof. Examples of mineral oils include paraffin oil, aromatic oils, naphthenic oils, and the like. Examples of vegetable oils (or fats and oils) include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, 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 the like. These may be used alone or in combination of two or more.

[0047] <Second Resin> The second resin is not particularly limited, and examples thereof include petroleum resins, terpene resins, rosin resins, and phenol resins commonly used in the tire industry. Of these, petroleum resins are preferred. The second resin may be used alone or in combination of two or more. When the first resin is used as the material of the retaining layer, the second resin as a plasticizer is selected from a different type from the first resin.

[0048] Examples of the petroleum resin include C5 petroleum resin, aromatic petroleum resin, C5C9 petroleum resin, etc. Among these, aromatic petroleum resin is preferred.

[0049] "C5 petroleum resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. As a C5 petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0050] The term "aromatic petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified resin. Examples of the C9 fraction include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins include coumarone-indene resins and aromatic vinyl resins. Among these, coumarone-indene resins are preferred. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, because they are economical, easy to process, and have excellent heat generation properties. As aromatic vinyl resins, for example, those commercially available from Kraton, Eastman Chemical, etc. can be used.

[0051] "C5C9 petroleum resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of the C5 fraction and the C9 fraction include the petroleum fractions mentioned above. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

[0052] Examples of the terpene resin include polyterpene resins consisting of at least one selected from terpene compounds such as α-pinene, β-pinene, limonene, and dipentene; aromatic modified terpene resins made from the terpene compounds and aromatic compounds; terpene phenolic resins made from terpene compounds and phenolic compounds; and terpene resins obtained by subjecting these terpene resins to hydrogenation treatment (hydrogenated terpene resins). Examples of aromatic compounds that are raw materials for aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds that are raw materials for terpene phenolic resins include phenol, bisphenol A, cresol, and xylenol.

[0053] Examples of rosin-based resins include natural resin rosins such as tall rosin, gum rosin, and wood rosin, and rosin-modified resins obtained by modifying natural resin rosins by hydrogenation, disproportionation, dimerization, esterification, and the like.

[0054] Examples of the phenol-based resin include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, and oil-modified phenol formaldehyde resin.

[0055] The softening point of the second resin is not particularly limited, but it is preferable that the second resin has a low softening point and is liquid, since it is easy to add. Therefore, when considering such a viewpoint, the softening point of the second resin is usually preferably higher than 0°C, more preferably higher than 5°C, and even more preferably higher than 10°C. The softening point of the second resin is preferably lower than 150°C, more preferably lower than 140°C, even more preferably lower than 130°C, even more preferably lower than 80°C, even more preferably lower than 50°C, even more preferably lower than 25°C, and even more preferably lower than 20°C. In this specification, the softening point can be defined as the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point measuring device. The molecular weight (Mw) of the second resin is preferably 300 or more, and preferably less than 10,000.

[0056] <Liquid rubber> The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25° C.), but examples thereof include diene polymers having a weight average molecular weight of 50,000 or less, more preferably 10,000 or less, and more specifically, liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid rubber may be used alone or in combination of two or more kinds.

[0057] <Ester-based plasticizers> Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), etc. The ester-based plasticizers may be used alone or in combination of two or more.

[0058] (Anti-aging agent) Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of the antioxidant include p-phenylenediamine antioxidants such as quinolinone, quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline, monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Commercially available products include those manufactured by Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. The antioxidants may be used alone or in combination of two or more.

[0059] (Vulcanization accelerator) Examples of the vulcanization accelerator include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators.

[0060] Examples of sulfenamide vulcanization accelerators include CBS (N-cyclohexyl-2-benzothiazolyl sulfenamide), TBBS (Nt-butyl-2-benzothiazolyl sulfenamide), N-oxyethylene-2-benzothiazolyl sulfenamide, N,N'-diisopropyl-2-benzothiazolyl sulfenamide, and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide. Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole and dibenzothiazolyl disulfide. Examples of thiuram vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine vulcanization accelerators include diphenylguanidine (DPG), di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more.

[0061] The other additives may be materials that are generally used in tires, such as wax, surfactants, and vulcanization-related chemicals other than the vulcanization accelerators.

[0062] <Repair sheet> The repair sheet to which the present disclosure is directed includes both those having a retaining layer in a state in which the additive is not held, and those having a retaining layer in a state in which the additive is held. When processing a tire using the repair sheet, the additive is held in the retaining layer. The additive may be held in the retaining layer by impregnating or injecting the additive into a retaining layer in a state in which the additive is not held, so that the retaining layer holds the additive, or the additive may be held when the retaining layer is prepared.

[0063] The repair sheet of the present disclosure is preferably applied directly to the portion of the tire exposed to the outside, such as the tread portion, sidewall portion, clinch portion, and wing portion of the outer surface, and the inner liner portion of the inner surface. In this case, since the repair sheet of the present disclosure has a predetermined breaking strength and breaking elongation, the work of applying the sheet to the tire can be efficiently performed. In addition, the amount of additives supplied to the tire can be adjusted by the time that the repair sheet holding the additives is brought into contact with the tire, i.e., the repair time, and can also be adjusted by the amount of additives held by the repair sheet. Therefore, the tire can be processed with less effort.

[0064] The repair sheet of the present disclosure preferably has a shape and size necessary and sufficient to cover a tire part. For example, when the repair sheet of the present disclosure is used to repair a tread, the repair sheet preferably has a vertical length of not more than the tire width plus 10 mm, a horizontal length of not more than the tire circumference plus 10 mm, and a thickness of not more than 110 mm. Those skilled in the art can determine the necessary and sufficient shape and size of the repair sheet of the present disclosure according to the shape and size of the tire part.

[0065] (Support layer) The repair sheet of the present disclosure may have a support layer that supports the retaining layer. By providing the repair sheet with a support layer, it is possible to obtain an advantage that the repair sheet can be easily handled until the retaining layer holding the additive is attached to the tire. The support layer is preferably one that does not hinder the deformation of the retaining layer when attached to the tire, and examples thereof include those made of a material (such as rubber or a thermoplastic elastomer) that is more stretchable than the retaining layer.

[0066] <Manufacturing method> The manufacturing method of the repair sheet of the present disclosure will be described below.

[0067] (retention layer) The retaining layer of the repair sheet can be manufactured by molding a predetermined material so that it can retain the additive and has a predetermined breaking strength and breaking elongation. A person skilled in the art can select such a predetermined material and appropriately set the molding conditions of the selected material.

[0068] <Retention layer made of thermoplastic elastomer> The retaining layer using a thermoplastic elastomer as a material (substrate) can be manufactured by, for example, press molding a material containing a pellet-shaped thermoplastic elastomer. The pressure, time, and temperature of the press molding can be appropriately set in an appropriate combination depending on the type of thermoplastic elastomer. Usually, the pressure of the press molding (unit: MPa) is preferably more than 0.1, more preferably more than 0.2, and even more preferably more than 0.4. On the other hand, the pressure is preferably less than 30, more preferably less than 25, and even more preferably less than 20. The time of the press molding is preferably more than 1 minute, more preferably more than 2 minutes, and even more preferably more than 3 minutes. On the other hand, the time is preferably less than 20 minutes, more preferably less than 15 minutes, and even more preferably less than 10 minutes. The temperature of the press molding can be appropriately set depending on the type of thermoplastic elastomer used.

[0069] In the above, the breaking strength of the retaining layer can be adjusted by selecting the type of thermoplastic elastomer used, and can also be adjusted by kneading in a material other than the additive of the present disclosure, such as a reinforcing material that does not penetrate into the tire, such as carbon black or silica. For example, the breaking strength can be increased by kneading in a large amount of reinforcing material, and conversely, the breaking strength can be decreased by kneading in a smaller amount. The reinforcing material can be kneaded into the material constituting the retaining layer using a Banbury mixer or the like. Note that, when a material other than the additive (e.g., a reinforcing material) is used as the material of the retaining layer, as described above, the material (reinforcing material) can be considered to be included in the retaining layer (the same applies below).

[0070] The breaking elongation of the retaining layer can be adjusted by selecting the type of thermoplastic elastomer used, and can also be adjusted by kneading in a material other than the additive of the present disclosure, such as carbon black, silica, or other reinforcing material that does not penetrate into the tire.

[0071] <Retention layer made of the first resin> The support layer using the first resin as a material (substrate) can be manufactured by, for example, press molding a material containing the first resin in pellet form. The pressure, time, and temperature of the press molding can be appropriately set to an appropriate combination depending on the type of the first resin. Usually, the pressure (unit: MPa) of the press molding is preferably more than 0.1, more preferably more than 0.2, and even more preferably more than 0.4. On the other hand, the pressure is preferably less than 30, more preferably less than 25, and even more preferably less than 20. The time of the press molding is preferably more than 1 minute, more preferably more than 2 minutes, and even more preferably more than 3 minutes. On the other hand, the time is preferably less than 20 minutes, more preferably less than 15 minutes, and even more preferably less than 10 minutes. The temperature of the press molding can be appropriately set depending on the type of the first resin used.

[0072] In the above, the breaking strength of the support layer can be adjusted by selecting the type of the first resin used. For example, the breaking strength can be increased by using a first resin having a large strength such as tensile strength, and conversely, the breaking strength can be decreased by using a first resin having a small strength.

[0073] The breaking elongation of the retaining layer can be adjusted by selecting the type of first resin used, and can also be adjusted by kneading in a material other than the additive of the present disclosure, such as carbon black, silica, or other reinforcing material that does not penetrate into the tire.

[0074] <Retention layer made of cross-linked rubber> The support layer made of crosslinked rubber as the material (substrate) can be produced, for example, by crosslinking chain rubber molecules with a co-crosslinking agent, an organic peroxide, sulfur, or the like.

[0075] In the above, the breaking strength of the retaining layer can be increased by increasing the density of the crosslinks, and can also be increased by kneading in a material other than the additive of the present disclosure, such as a reinforcing material that does not penetrate into the tire, such as carbon black, silica, etc. Conversely, the breaking strength can be decreased by decreasing the density of the crosslinks, and can also be decreased by reducing the amount of the reinforcing material.

[0076] Even when the material (substrate) of the retaining layer is a combination of two or more selected from a thermoplastic elastomer, a first resin, and a crosslinked rubber, the desired retaining layer can be manufactured by appropriately referring to the manufacturing methods when using the various materials described above.

[0077] (Repair sheet containing additives) The additive can be retained in the retaining layer by immersing the retaining layer in the additive or by injecting the additive into the retaining layer. The additive may be at room temperature or at a heated temperature within a range that does not affect the structure or function of the retaining layer. Alternatively, the material (substrate) of the retaining layer and the additive may be mixed and then press molded as in the above manufacturing method. However, it is preferable to immerse the retaining layer in the additive or to inject the additive into the retaining layer, since the amount of additive can be adjusted.

[0078] (Repair sheet with support layer) The repair sheet with a support layer can be manufactured by adhering the support layer before the support layer is provided to the support layer. The adhesion is not particularly limited as long as the adhesion between the support layer before the support layer is provided and the support layer can be adhered with an adhesive strength equal to or greater than the minimum adhesive strength required. For example, if the two are to be adhered as they are, the adhesion can be carried out by doing so, or, if necessary, by using an appropriate adhesive. However, if the support layer is to be separated during use, the adhesion is preferably within a range of adhesive strength that allows easy separation. The "minimum adhesive strength" refers to the minimum adhesive strength required for the support layer and the support layer to adhere to each other after the support layer is adhered to the support layer and until the support layer is peeled off from the repair sheet.

[0079] [How to repair tires] The tire repair method of the present disclosure is a tire repair method including the steps of attaching the repair sheet to a tire portion, and supplying the additive to the inside of the tire portion.

[0080] The tire repair method of the present disclosure can be carried out by directly attaching the repair sheet to the portion of the tire exposed to the outside, such as the tread portion, sidewall portion, clinch portion, and wing portion of the outer surface, and the inner liner portion of the inner surface. In this case, since the repair sheet has a predetermined breaking strength and breaking elongation, the work of attaching the repair sheet to the tire can be carried out efficiently. In addition, the amount of additives supplied to the tire can be adjusted by the time that the repair sheet holding the additives is contacted with the tire, i.e., the repair time, and can also be adjusted by the amount of additives held in the repair sheet. Therefore, the tire can be processed with less effort.

[0081] The explanation of the repair sheet can also be applied to the explanation of this repair method unless there is a particular contradiction.

[0082] [Application] The repair sheet of the present disclosure can be used to repair tires used on a wide variety of vehicles, such as passenger cars, large vehicles such as trucks and buses, motorcycles, racing vehicles, industrial vehicles, special vehicles, and load-bearing vehicles such as trailers and dollies. Such tires are not limited to pneumatic tires, and may be non-pneumatic tires. In particular, studless tires contain a larger amount of additives than normal tires in order to obtain a ground contact effect and edge effect on snowy and icy roads, and therefore the hardening of rubber tends to progress over time, so the repair sheet of the present disclosure can be suitably used. The part of the tire to which the repair sheet of the present disclosure is applied is not particularly limited, but is generally the tread part, sidewall part, clinch part, wing part, inner liner part, etc. that constitute the surface including the outer surface or inner surface of the tire, and can be particularly suitably applied to the tread part. EXAMPLES

[0083] Hereinafter, the present disclosure will be described based on examples, but the present disclosure is not limited to these examples.

[0084] The materials used in the examples and comparative examples are summarized below. Thermoplastic elastomer: Asahi Kasei Corporation, Tuftec (registered trademark) P1500 (hydrogenated styrene-based thermoplastic elastomer, styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene / ethylene-butylene-butadiene ratio: 30 / 70) First resin: Asahi Kasei Corporation, Asaflex (registered trademark) 815 (styrene-based resin, styrene-butadiene copolymer resin (SBC), tensile strength (50 mm / min): 27 MPa, Vicat softening temperature: 82°C) Crosslinked rubber: Crosslinked rubber obtained in Production Example 1 described below Oil: Idemitsu Kosan Co., Ltd., PS-32 (mineral oil) Second resin: NOVARES C10 (liquid coumarone-indene resin) manufactured by Rutgers Chemicals Ester plasticizer: bis(2-ethylhexyl) sebacate (dioctyl sebacate), manufactured by Daihachi Chemical Industry Co., Ltd. Anti-aging agent: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0085] [Experimental Example 1] <Repair sheet> (retention layer 1) The pelletized thermoplastic elastomer was pressed using a rubber press molding machine at 170°C for 5 minutes under 1 MPa to produce a repair sheet, the retaining layer 1. The retaining layer 1 thus obtained was cut into a size of 20 mm length (tire width direction) × 30 mm width (tire circumferential direction) × 2 mm thickness.

[0086] (retention layer 2) The pellet-shaped first resin was pressed using a vacuum press molding machine under conditions of 140°C, 5 minutes, and 10 MPa to produce a repair sheet, the retaining layer 2. The retaining layer 2 thus obtained was cut into a size of 20 mm length (tire width direction) × 30 mm width (tire circumferential direction) × 2 mm thickness.

[0087] (retention layer 3) The crosslinked rubber was pressed using a rubber vulcanizing press molding machine at 170°C for 20 minutes under 10 MPa to produce a repair sheet, the retaining layer 3. The retaining layer 3 thus obtained was cut into a size of 20 mm length (tire width direction) × 30 mm width (tire circumferential direction) × 2 mm thickness.

[0088] The breaking strength and breaking elongation of the thus obtained support layer 1, support layer 2, and support layer 3 were measured as follows. The results are shown in Table 1.

[0089] (Breaking strength, breaking elongation) Test pieces in the shape of a No. 7 dumbbell and having a thickness of 1 mm were prepared by cutting out the retaining layers 1, 2, and 3 so that the tensile direction was the horizontal (circumferential direction of the tire) direction, and a tensile test was carried out in accordance with JIS K 6251 "Vulcanized rubber and thermoplastic rubber - Determination of tensile test characteristics" at an atmosphere of 23°C and a tensile speed of 3.3 mm / sec to measure the breaking strength (TB) (MPa) and breaking elongation (EB) (%).

[0090] [Table 1]

[0091] <Repair sheet with additives> Using the repair sheets obtained above, namely retaining layer 1, retaining layer 2 or retaining layer 3, immersion was performed under the additives and immersion conditions shown in Table 2 below to produce repair sheets 1 to 10 in which the additives were retained in the proportions shown in Table 2.

[0092] [Table 2]

[0093] <Tire repair> Used tire 0 and used tires 1 to 3 (all Winter Max 02 manufactured in 2018 (manufactured by Sumitomo Rubber Industries, Ltd.); 2-year-old product; same stencil) were prepared. All of these tires were mounted on the same vehicle. Of these, used tire 0 was used as a comparative example, and used tires 1 to 3 were used as examples. As shown in Table 3, used tire 0 of the comparative example was not repaired at all and was used as it was for tire evaluation. On the other hand, used tires 1 to 3 of the examples were repaired at room temperature (25°C) under the conditions shown in Table 3 and then used for tire evaluation.

[0094] <Tire evaluation> Each tire was evaluated as follows. The results are shown in Table 3.

[0095] (Additive content) The additive content was determined according to JIS K 6229 by immersing samples cut from the tread surface of each tire in acetone for 24 hours to extract the soluble components, measuring the mass of each sample before and after extraction, and calculating the amount of extractables according to the following formula. The amount of extractables (%) in Comparative Example 1 was set to 100 and expressed as an index. The larger the value, the greater the amount of extractables, i.e., the additive content. Extractables (%) = {(mass of sample before extraction - mass of sample after extraction)} / (mass of sample before extraction)}×100

[0096] (hardness) A sample for hardness measurement was cut from the tread portion forming the ground contact surface of each tire so that the tire radial direction was the thickness direction, and the rubber hardness was measured against the sample at 23°C by pressing a type A durometer against the ground contact surface side in accordance with JIS K 6253. The reciprocal of the hardness was expressed as an index, with the case of Comparative Example 1 being set at 100. The larger the value, the lower the hardness and the softer the tire.

[0097] (Wet grip performance and ice performance) Regarding wet grip performance, the road friction coefficient was measured using an inside drum tester at a drum speed of 20 km / h under wet road conditions (25°C, water depth of 5 mm) with the slip ratio changed from 0 to 30%. The road friction coefficient thus obtained was expressed as an index (wet grip performance index), with the value in Comparative Example 1 set at 100. The higher the value, the better the wet grip performance.

[0098] For the ice performance, the ice performance index was calculated in the same manner as for the wet grip performance index, except that the wet road conditions were replaced by frozen road conditions (-1°C, on ice). The higher the value, the better the ice performance.

[0099] [Table 3]

[0100] As is clear from Table 3, as a result of the repair, the additive content in the tread portion of the Example was increased compared to the Comparative Example, the hardness of the tread portion was reduced and it became softer, and further, the wet grip performance and the performance on ice were improved.

[0101] [Experimental Example 2] The results for Examples 4 and 5 were obtained by treating in the same manner as in Experimental Example 1, except that used tires 4 and used tires 5 (both were Winter Max 02 manufactured in 2018 (manufactured by Sumitomo Rubber Industries, Ltd.); tires with 2 years of mileage; same stencil) were prepared as tires to be repaired, a second resin and an ester-based plasticizer were used as additives to be retained in the retaining layer 1, and Table 4 was followed.

[0102] [Table 4]

[0103] As is clear from Table 4, as a result of the repair, the additive content in the tread portion of the Example was increased compared to the Comparative Example, the hardness of the tread portion was reduced and the tread portion became softer, and further, the wet grip performance and performance on ice were improved.

[0104] [Experimental Example 3] The results for Examples 6 to 8 were obtained by treating in the same manner as in Experimental Example 1, except that used tires 6 to 8 (all Winter Max 02 manufactured in 2018 (manufactured by Sumitomo Rubber Industries, Ltd.); tires with 2 years of mileage; same stencil) were prepared as tires to be repaired, an antioxidant was used as an additive to be retained in the retaining layer 1, ozone resistance was evaluated, and Table 5 was followed.

[0105] (Ozone resistance) The ozone resistance was evaluated by preparing a test piece of a predetermined size from the surface of the tread portion and performing a dynamic ozone deterioration test on the test piece in accordance with JIS K 6259 "Vulcanized rubber and thermoplastic rubber - Determination of ozone resistance". In detail, the test piece was subjected to a test of applying a reciprocating motion of a frequency of 0.5 ± 0.025 Hz for 48 hours under the conditions of an ozone concentration of 50 ± 5 pphm, a test temperature of 40 ° C, and a tensile strain of 10 ± 2%, and the state of cracks (presence or absence of cracks, number of cracks, length of cracks, etc.) generated on the test piece after the test was observed. The evaluation method used was the method described in JIS K 6259 (Method A: Crack state observation method). Specifically, the number of cracks of 0.05 mm or more confirmed after the test was multiplied by the average length of cracks of 0.05 mm or more to calculate a value indicating the degree of crack generation, and the reciprocal of the value was used as the evaluation value of the ozone resistance index. Therefore, the larger the numerical value is from the evaluation standard, 100, of the ozone resistance index of Comparative Example 2, the fewer cracks are generated and the smaller the size of the cracks, which indicates excellent ozone resistance.

[0106] [Table 5]

[0107] As is clear from Table 5, as a result of the repair, the additive content in the tread portion of the Example was increased compared to the Comparative Example, and the ozone resistance of the tread portion was improved.

[0108] [Experimental Example 4] The results for Examples 9 to 11 were obtained by treating in the same manner as in Experimental Example 1, except that used tires 9 to 11 (all Winter Max 02 manufactured in 2018 (manufactured by Sumitomo Rubber Industries, Ltd.); tires with 2 years of mileage; same stencil) were prepared as tires to be repaired, that retaining layer 2 was used as the retaining layer, and that the results were obtained in accordance with Table 6.

[0109] [Table 6]

[0110] As is clear from Table 6, as a result of the repair, the additive content in the tread portion of the Example increased compared to the Comparative Example, the hardness of the tread portion decreased and became softer, and further, the wet grip performance and performance on ice were improved.

[0111] [Experimental Example 5] Used tires 12 to 15 (all Winter Max 02 manufactured in 2018 (manufactured by Sumitomo Rubber Industries, Ltd.); 2-year-old tires; same stencil) were prepared as tires to be repaired. All of these tires were mounted on the same vehicle. Among them, used tire 12 was used as a comparative example, used tires 13 to 15 were used as examples, retaining layer 3 was used as the retaining layer, and the results for Examples 12 to 14 were obtained by treating them in the same manner as in Experimental Example 1, except that the results were obtained in accordance with Table 7.

[0112] [Table 7]

[0113] As is clear from Table 7, as a result of the repair, the additive content in the tread portion of the Example increased compared to the Comparative Example, the hardness of the tread portion decreased and became softer, and further, the wet grip performance and performance on ice were improved.

[0114] Manufacturing Example 1 A crosslinked rubber was produced according to the formulation in Table 8. That is, of the components listed in the table, all the components except for sulfur and vulcanization accelerator were used. component After mixing, sulfur and a vulcanization accelerator were added to the kneaded product and further kneaded to obtain a kneaded product. For kneading, a general internal kneader and a two-roll mill for rubber kneading were used. The kneaded product was vulcanized at 170°C for 20 minutes to obtain a crosslinked rubber composition.

[0115] [Table 8]

[0116] [Embodiment] Examples of embodiments of the present disclosure are given below.

[0117] [1] A repair sheet for attaching to a tire part, A retaining layer capable of retaining an additive for delivery to an interior of a tire portion, a repair sheet in which the retaining layer has a breaking strength of 0.5 MPa or more, preferably greater than 0.5 MPa, more preferably greater than 1.0 MPa, even more preferably greater than 1.5 MPa, even more preferably greater than 2.0 MPa, even more preferably greater than 3.0 MPa, even more preferably greater than 5.0 MPa, even more preferably greater than 10.0 MPa, even more preferably greater than 15.0 MPa, even more preferably greater than 17.0 MPa, and a breaking elongation of 5% or more, preferably greater than 5%, more preferably greater than 10%, even more preferably greater than 50%, even more preferably greater than 100%, even more preferably greater than 200%, even more preferably greater than 230%, even more preferably greater than 300%, even more preferably greater than 400%, even more preferably greater than 420%, even more preferably greater than 500%, even more preferably greater than 600%; [2] The repair sheet according to the above [1], wherein the retaining layer contains at least one selected from the group consisting of a thermoplastic elastomer, a resin, and a crosslinked rubber. [3] The repair sheet according to the above [1] or [2], wherein the thickness of the retaining layer is 100 mm or less, preferably 80 mm or less, more preferably 60 mm or less, and even more preferably 50 mm or less. [4] The repair sheet according to any one of the above [1] to [3], further comprising a support layer that supports the retaining layer. [5] The repair sheet according to any one of the above [1] to [4], wherein the additive is held in the holding layer. [6] The repair sheet according to the above [5], wherein the additive comprises at least one selected from the group consisting of a plasticizer, an antioxidant, and a vulcanization accelerator. [7] A method for repairing a tire, comprising: A tire repair method comprising the steps of: attaching the repair sheet according to the above item [5] or [6] to a tire portion; and supplying the additive to the inside of the tire portion. [8] The retaining layer has a vertical length of not more than the tire width plus 10 mm, a horizontal length of not more than the tire circumference plus 10 mm, and a thickness of not more than 110 mm; The repair method according to [7] above, wherein the tire portion is a tread portion of the tire.

Claims

1. A repair sheet to be attached to a part of a tire for the purpose of processing the tire by supplying an additive to the inside of the part of the tire in order to improve or maintain the performance of a used tire, or to improve or modify the performance of a new tire, a retaining layer capable of retaining an additive to be supplied to the inside of the tire portion; A repair sheet in which the retaining layer has a breaking strength of 0.5 MPa or more and a breaking elongation of 5% or more.

2. 2. The repair sheet according to claim 1, wherein the retaining layer comprises at least one selected from the group consisting of a thermoplastic elastomer, a resin, and a crosslinked rubber.

3. 3. The repair sheet according to claim 1, wherein the thickness of the retaining layer is 100 mm or less.

4. The repair sheet according to claim 1 or 2, further comprising a support layer that supports the retaining layer.

5. 3. The repair sheet according to claim 1, wherein the additive is retained in the retaining layer.

6. 6. The repair sheet according to claim 5, wherein the additive comprises at least one selected from the group consisting of a plasticizer, an antioxidant, and a vulcanization accelerator.

7. A method for repairing a tire, comprising: A method for repairing a tire, comprising the steps of: attaching the repair sheet according to claim 5 to a tire portion; and supplying the additive to the inside of the tire portion.

8. The retaining layer has a vertical length of not more than the tire width plus 10 mm, a horizontal length of not more than the tire outer circumference plus 10 mm, and a thickness of not more than 110 mm, The repair method according to claim 7 , wherein the tire portion is a tread portion of the tire.

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