vulcanized rubber surface treatment agents, manufacturing methods of adhesive structures, adhesive structures, and tires

Abstract

Provided is a vulcanized rubber surface treatment agent that enables vulcanized rubber sheets to bond firmly to each other without heating, with minimal impact on rubber degradation. The vulcanized rubber surface treatment agent is characterized by its use in bonding vulcanized rubber sheets to each other, and it is an aqueous solution of hypochlorous acid with a pH of 2-7 and an effective chlorine concentration of 100-13000 ppm.

Description

Technical Field

[0001] This invention relates to vulcanized rubber surface treatment agents, methods for manufacturing adhesive structures, adhesive structures, and tires. Background Technology

[0002] In recent years, from the perspective of conserving resources and reducing initial costs, various tires have been reused by repairing deteriorated parts caused by tire use or by replacing a portion of the tire. Specific examples include retreading, replacing worn treads, re-siding, replacing a portion of the sidewall damaged by curbs on sidewalks, and repairing cracks on the tire surface.

[0003] The aforementioned tire repair and reuse techniques typically require bonding between vulcanized rubber components, particularly between vulcanized rubber components, which naturally necessitates good adhesion between the components. Furthermore, it is important that the repaired portion of the tire exhibits good fatigue resistance (the ability to withstand tire deformation) when reused. In addition, ease of use is also crucial during operations such as repair.

[0004] For example, PTL 1 (JP H01-131291 A) describes a method of bonding rubber firmly and stably to another component by applying (1) a primer mainly composed of halogenated polyolefins, (2) a rubber-based adhesive mainly composed of halogenated rubbers and (3) a polyurethane-based adhesive to the surface of a rubber in the order described, and then clamping these materials between the rubber and other components.

[0005] Reference List

[0006] Patent documents

[0007] PTL 1: JP H01-131291 A Summary of the Invention

[0008] The problem the invention aims to solve

[0009] PTL 1's technology achieves adhesion through hot-press bonding. Therefore, it presents difficulties when installing tires, especially large ones. Given that tires are frequently repaired on-site, it is desirable for vulcanized rubber components to bond firmly to each other without heating.

[0010] Furthermore, the prior art described in PTL 1 involves coating the rubber surface with an organic solvent, which may degrade the rubber.

[0011] Based on the above, it is desirable to develop a treatment agent that provides the desired specific activity when applied to the surface of vulcanized rubber.

[0012] Therefore, it is helpful to provide a vulcanized rubber surface treatment agent that can achieve strong adhesion between vulcanized rubbers without heating and has little impact on rubber deterioration.

[0013] Furthermore, it is helpful to provide a method for manufacturing an adhesive structure in which vulcanized rubber is firmly bonded to each other without heating.

[0014] Furthermore, it is helpful to provide an adhesive structure with excellent fatigue resistance, wherein vulcanized rubber is firmly bonded to each other, and to provide a tire having the adhesive structure.

[0015] Solution for solving the problem

[0016] Therefore, we provide the following

[0017] The vulcanized rubber surface treatment agent of the present invention is a vulcanized rubber surface treatment agent for bonding vulcanized rubbers together, which is...

[0018] A hypochlorous acid aqueous solution with a pH value between 2 and 7 and an effective chlorine concentration between 100 ppm and 13000 ppm.

[0019] The method for manufacturing an adhesive structure according to the present invention is a method for manufacturing an adhesive structure, which is used to obtain an adhesive structure in which a first vulcanized rubber and a second vulcanized rubber are bonded together, the method comprising:

[0020] The first coating process involves applying an aqueous solution of hypochlorous acid with a pH value of 2 or higher and 7 or lower, and an effective chlorine concentration of 100 ppm or higher and 13000 ppm or lower, to the surface of the first vulcanized rubber.

[0021] The second coating step involves applying an adhesive to the surface of the hypochlorous acid aqueous solution coated in the first coating step, and

[0022] An adhesive bonding process in which the first vulcanized rubber and the second vulcanized rubber are bonded together by means of the hypochlorous acid aqueous solution applied in the first coating process and the adhesive applied in the second coating process.

[0023] The adhesive structure of the present invention is an adhesive structure in which a first vulcanized rubber and a second vulcanized rubber are bonded together via an adhesive layer, wherein...

[0024] The adhesive layer comprises a polyurethane compound and / or an epoxy compound, and

[0025] At least a portion of the surfaces of the first and second vulcanized rubbers that are in contact with the adhesive layer are chlorinated.

[0026] The tire of the present invention has an adhesive structure.

[0027] The effects of the invention

[0028] According to the present invention, a vulcanized rubber surface treatment agent can be provided, which can achieve strong adhesion between vulcanized rubbers without heating and has little impact on rubber deterioration.

[0029] Furthermore, according to the present invention, a method for manufacturing an adhesive structure can be provided, wherein the adhesive structure in which vulcanized rubber is firmly bonded to each other can be manufactured without heating.

[0030] Furthermore, according to the present invention, an adhesive structure with excellent fatigue resistance can be provided, wherein vulcanized rubber is firmly bonded to each other, and a tire having the adhesive structure can be provided. Detailed Implementation

[0031] The present invention will now be described in detail based on the implementation scheme.

[0032] (Vulcanized rubber surface treatment agent)

[0033] A surface treatment agent for vulcanized rubber (hereinafter, it may be referred to as "the surface treatment agent of this embodiment") according to one embodiment of the present invention is used to bond vulcanized rubber together. The surface treatment agent of this embodiment is an aqueous solution of hypochlorous acid with a pH value of 2 or higher and 7 or lower and an effective chlorine concentration of 100 ppm or higher and 13000 ppm or lower.

[0034] In aqueous hypochlorous acid solutions with a pH value between 2 and 7, hypochlorous acid usually exists in the form of molecules (HClO).

[0035] We have conducted an in-depth study on methods to improve the adhesion between vulcanized rubbers. As a result, we found that good adhesion can be achieved without heating by surface-treating at least one of the vulcanized rubbers with an aqueous hypochlorous acid solution before bonding them together using an adhesive. Aqueous hypochlorous acid solutions are known to be commonly used for disinfection and deodorization. Therefore, it can be said that using an aqueous hypochlorous acid solution as a surface treatment agent to improve the adhesion between vulcanized rubbers is a novel and surprising discovery.

[0036] Because the surface treatment agent of this embodiment is an aqueous solution (which does not contain organic solvents), it has minimal adverse environmental impact and causes almost no degradation to the vulcanized rubber in direct contact. Therefore, the adhesive structure obtained by applying the surface treatment agent of this embodiment to the surface of the vulcanized rubber and sandwiching the adhesive between the vulcanized rubbers not only has high adhesion but also significant resistance to deformation and strain (and good fatigue resistance).

[0037] Furthermore, hypochlorous acid aqueous solution has the advantage of being easily prepared using commercially available raw materials.

[0038] When an aqueous solution of hypochlorous acid is applied to the surface of vulcanized rubber, it is believed that an oxidation (chlorination) reaction of the olefin moiety occurs in at least a portion of the vulcanized rubber surface. It is thought that during the oxidation (chlorination) reaction, chlorine and hydroxyl groups are introduced into the carbon atoms forming C=C double bonds in the rubber molecules present on the vulcanized rubber surface via a mechanism. Furthermore, it is believed that the introduction of these groups increases the polarity and wettability of the vulcanized rubber surface, which contributes to strong adhesion. Therefore, it is necessary for a certain amount of hypochlorous acid to exist in the aqueous solution in molecular form (HClO), because if hypochlorous acid exists only in ionic form, the polarity of the vulcanized rubber surface cannot be sufficiently increased. Whether hypochlorous acid exists in molecular or ionic form in the aqueous solution can be determined from the pH value of the aqueous solution. It is believed that when the pH value is below 7, sufficient hypochlorous acid molecules are present to increase the polarity of the vulcanized rubber surface.

[0039] [Chemistry 1]

[0040]

[0041] The hypochlorous acid aqueous solution used as a surface treatment agent in this embodiment can, for example, be used in the manufacturing method of the adhesive structure described below.

[0042] As described above, the hypochlorous acid aqueous solution used as the surface treatment agent in this embodiment has a pH value of 2 or higher and 7 or lower. When the pH value is less than 2, a large amount of chlorine gas is released, making it difficult to maintain the effective chlorine concentration within a predetermined range. When the pH value is greater than 7, the effect of improving the adhesion between vulcanized rubbers cannot be sufficiently obtained. Furthermore, from the viewpoint of stability, the pH value of the hypochlorous acid aqueous solution is more preferably 4 or higher.

[0043] As described above, the effective chlorine concentration of the hypochlorous acid aqueous solution used as the surface treatment agent in this embodiment is 100 ppm or more and 13,000 ppm or less. When the effective chlorine concentration is less than 100 ppm, the effect of improving the adhesion between vulcanized rubbers cannot be sufficiently obtained. When the effective chlorine concentration exceeds 13,000 ppm, the adhesion between vulcanized rubbers deteriorates, and there is a risk to human health. From the same viewpoint, the effective chlorine concentration of the hypochlorous acid aqueous solution is preferably 200 ppm or more, and more preferably 300 ppm or more. It is preferably 8,000 ppm or less, more preferably 4,000 ppm or less, even more preferably 1,000 ppm or less, and even more preferably 500 ppm or less.

[0044] The effective chlorine concentration of the hypochlorous acid aqueous solution can be adjusted, for example, by the dilution ratio during the preparation of the aqueous solution, which is obtained by dissolving hypochlorite such as sodium hypochlorite in water.

[0045] The pH of a hypochlorous acid aqueous solution can be lowered, for example, by adding hydrochloric acid, and the pH can be adjusted by the proportion of hydrochloric acid added. An aqueous solution obtained by dissolving sodium hypochlorite in water has a pH of approximately 9–10. If a large amount of chlorine is added to the hypochlorous acid aqueous solution or added rapidly, chlorine gas will be formed, and the effective chlorine concentration will decrease accordingly; this should be taken into account when adjusting the solution.

[0046] (Manufacturing method of adhesive structure)

[0047] A method for manufacturing an adhesive structure according to one embodiment of the present invention (hereinafter, it may be referred to as "the manufacturing method of this embodiment") is a method for manufacturing an adhesive structure, which is used to obtain an adhesive structure in which a first vulcanized rubber and a second vulcanized rubber are bonded together. Specifically, the manufacturing method of this embodiment includes...

[0048] The first coating process involves applying an aqueous solution of hypochlorous acid with a pH value of 2 or higher and 7 or lower, and an effective chlorine concentration of 100 ppm or higher and 13000 ppm or lower, to the surface of the first vulcanized rubber.

[0049] The second coating step involves applying the adhesive to the surface of the hypochlorous acid aqueous solution coated in the first coating step, and

[0050] An adhesive bonding process in which the first vulcanized rubber and the second vulcanized rubber are bonded together by the hypochlorous acid aqueous solution applied in the first coating process and the adhesive applied in the second coating process.

[0051] According to the manufacturing method of this embodiment, an adhesive structure can be manufactured in which vulcanized rubber is firmly bonded to each other without heating. Furthermore, the adhesive structure obtained by the manufacturing method of this embodiment exhibits significant resistance to deformation and strain (and thus good fatigue resistance).

[0052] Vulcanized rubber (first and second vulcanized rubber) can be prepared by vulcanizing a rubber composition containing rubber components. Examples of rubber components include natural rubber, as well as diene-based rubber components such as butadiene rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene-diene copolymer, and acrylonitrile-butadiene rubber. Rubber components can be used alone or in combination of two or more. Furthermore, the vulcanized rubber and the rubber composition used to prepare the vulcanized rubber may, depending on the purpose, include appropriate amounts of additives such as fillers like carbon black, vulcanizing agents like sulfur, vulcanization accelerators, vulcanization accelerator aids, zinc oxide, antioxidants, foaming agents, plasticizers, lubricants, tackifiers, and UV absorbers. There are no particular limitations on the vulcanization conditions.

[0053] In addition, depending on the purpose, vulcanized rubber can be provided with components other than rubber, such as fiber components and metal components.

[0054] Examples of antioxidants include aromatic secondary amine antioxidants, phenolic antioxidants, sulfur-based antioxidants, and phosphite-based antioxidants.

[0055] Examples of aromatic secondary amine antioxidants include p-phenylenediamine antioxidants such as N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), N-(3-methacryloyloxy-2-hydroxypropyl)-N'-phenyl-p-phenylenediamine, and N-cyclohexyl-N'-phenyl-p-phenylenediamine; diphenylamine antioxidants such as p-(p-toluenesulfonamide)diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (CD), octylated diphenylamine (ODPA), and stylated diphenylamine; and naphthylamine antioxidants such as N-phenyl-1-naphthylamine (PAN) and N-phenyl-2-naphthylamine (PBN).

[0056] Aromatic secondary amine antioxidants are preferably p-phenylenediamine-based antioxidants. P-phenylenediamine-based antioxidants preferably have a structure without double bonds except for the phenylenediamine moiety, and more preferably are p-phenylenediamine compounds represented by the following general formula (1).

[0057] [Chemistry 2]

[0058]

[0059] Where R 1 and R 2 Each is an independent monovalent saturated hydrocarbon group. R 1 and R 2 They can be the same or different, but from the point of view of synthesis, they are preferably the same.

[0060] The monovalent saturated hydrocarbon group preferably has 1 to 20 carbon atoms, more preferably 3 to 10 carbon atoms, and particularly preferably 6 or 7 carbon atoms. When the saturated hydrocarbon group has 20 or fewer carbon atoms, the molar number per unit mass increases. As a result, the anti-aging effect increases, and the ozone resistance of the vulcanized rubber and / or rubber composition is improved.

[0061] From the viewpoint of further improving the ozone resistance of vulcanized rubber and / or rubber compositions, R in general formula (1) 1 and R 2 Preferably, each is an independent chain or cyclic monovalent saturated hydrocarbon group having 1 to 20 carbon atoms.

[0062] Examples of monovalent saturated hydrocarbon groups include alkyl and cycloalkyl groups. Alkyl groups can be straight-chain or branched, and cycloalkyl groups can be further bonded to alkyl groups as substituents.

[0063] Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,4-dimethylpentyl, n-hexyl, 1-methylhexyl, 2-methylhexyl, various octyl groups, various decyl groups, and various dodecyl groups. Among the above, 1,4-dimethylpentyl is preferred.

[0064] Examples of cycloalkyl groups include cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, and cyclooctyl. Among these, cyclohexyl is preferred.

[0065] p-Phenylenediamine compounds represented by general formula (1) can be supported on any support. For example, p-Phenylenediamine compounds represented by general formula (1) can be supported on inorganic fillers such as silica or calcium carbonate.

[0066] p-phenylenediamine compounds represented by general formula (1) can be used together with rubber components used in vulcanized rubber to form a masterbatch.

[0067] The p-phenylenediamine compounds represented by general formula (1) can be salts of organic acids. There are no particular limitations on the organic acids used to form the salts, and examples include stearic acid.

[0068] The concentration of the aromatic secondary amine antioxidant in the first and second vulcanized rubbers is preferably 1% by mass or less. Since the aromatic secondary amine antioxidant may have unintended effects on the adhesion between the vulcanized rubbers, suppressing the concentration to below 1% by mass can maintain sufficiently good adhesion between the vulcanized rubbers. The concentration of each component in the vulcanized rubber can generally be calculated from the chemical composition (blending ratio) of the rubber composition used to prepare the vulcanized rubber.

[0069] However, since the bonding is carried out on the surface of the vulcanized rubber, the above-mentioned concentration should be met at least in the surface layer of the vulcanized rubber. Specifically, the concentration of the aromatic secondary amine antioxidant in the first and second vulcanized rubbers (in the subsequent bonding process) is preferably 1% by mass or less in a region 10 μm deep from the surface in contact with the adhesive.

[0070] The concentration in a region 10 μm deep from the surface of the vulcanized rubber can be measured, for example, by gas chromatography of a surface-swept sample.

[0071] The concentration of aromatic secondary amine antioxidants in the surface layer of vulcanized rubber can be reduced, for example, by treating the surface of the vulcanized rubber with an organic solvent such as acetone (e.g., wiping the surface with a waste cloth soaked in solvent).

[0072] From the same point of view, the concentration of the aromatic secondary amine antioxidant in the first vulcanized rubber and the second vulcanized rubber (or their surface layers) is more preferably 0.6% by mass or less, and even more preferably 0.3% by mass or less, and may be 0% by mass.

[0073] The first and second vulcanized rubbers can be independent vulcanized rubber components, or they can be components located at any two positions within a single vulcanized rubber component. Furthermore, the first and second vulcanized rubbers can be the same or different in terms of rubber type, component shape, and the content of various additives.

[0074] In the first coating step, an aqueous solution of hypochlorous acid with a pH value of 2 or higher and 7 or lower, and an effective chlorine concentration of 100 ppm or higher and 13000 ppm or lower, is applied to the surface of the first vulcanized rubber. In this step, the bonding surface of the vulcanized rubber is treated with an aqueous solution (free of organic solvents), which effectively inhibits rubber deterioration. There are no particular limitations on the coating amount, and it can be any amount sufficient to cover the surfaces to be bonded. There are no particular limitations on the coating method.

[0075] From a stability point of view, the pH value of the hypochlorous acid aqueous solution used in the first coating step is preferably 4 or higher and 7 or lower.

[0076] In the manufacturing method of this embodiment, it is preferable to coat the surface of the second vulcanized rubber with an aqueous solution of hypochlorous acid, just like the first vulcanized rubber.

[0077] Next, in the second coating step, the adhesive is applied to the surface of the hypochlorous acid aqueous solution applied in the first coating step. There are no particular limitations on the coating amount, and it can be the amount of hypochlorous acid aqueous solution covering the surface of the first vulcanized rubber. There are no particular limitations on the coating method.

[0078] There are no particular limitations on the adhesive, and it can be appropriately selected according to the purpose. The adhesive can be used alone or in combination of two or more. In particular, it is preferred to use an adhesive that can achieve adhesion at room temperature. Furthermore, from the viewpoint of achieving sufficiently good adhesion, it is preferred to use polyurethane-based adhesives and / or epoxy-based adhesives. In this case, the vulcanized rubbers can bond more firmly to each other.

[0079] Next, in the bonding process, the first vulcanized rubber and the second vulcanized rubber are bonded together via the hypochlorous acid aqueous solution applied in the first coating process and the adhesive applied in the second coating process. As a result, an adhesive structure in which the two vulcanized rubbers are firmly bonded together is obtained. More specifically, in the bonding process, the first vulcanized rubber and the second vulcanized rubber can be bonded together by adhering them together via the coated materials and applying appropriate pressure. When both the first vulcanized rubber and the second vulcanized rubber are coated, the coated surfaces of the two vulcanized rubbers can be adhered together facing each other.

[0080] After the first and second vulcanized rubbers are bonded together, drying is preferably performed to remove moisture from the hypochlorous acid aqueous solution. In this case, the drying temperature can be room temperature. The drying time can be, for example, about 2 to 7 days.

[0081] The above process can be used to obtain an adhesive structure in which the first vulcanized rubber and the second vulcanized rubber are bonded together.

[0082] In the manufacturing method of this embodiment, a grinding process can be performed beforehand, in which the bonding surfaces of the first vulcanized rubber and the second vulcanized rubber are ground with a grinding stone or the like. In this case, the adhesion can be further improved by the anchoring effect.

[0083] In the manufacturing method of this embodiment, a step can be performed beforehand in which the surfaces of the first and second vulcanized rubbers to be bonded are treated with an organic solvent such as acetone to reduce the concentration of a predetermined component (such as an aromatic secondary amine antioxidant) in the surface layer. This step is particularly useful when the concentration of the aromatic secondary amine antioxidant in the rubber composition used to prepare the vulcanized rubber is relatively high.

[0084] (Adhesive structure)

[0085] An adhesive structure according to one embodiment of the present invention (hereinafter, it may be referred to as "the adhesive structure of this embodiment") is an adhesive structure in which a first vulcanized rubber and a second vulcanized rubber are bonded to each other via an adhesive layer, wherein

[0086] The adhesive layer contains polyurethane compounds and / or epoxy compounds, and

[0087] At least a portion of the surfaces of the first and second vulcanized rubbers that are in contact with the adhesive layer are chlorinated.

[0088] The adhesive structure of this embodiment has excellent fatigue resistance, wherein the vulcanized rubber is firmly bonded to each other.

[0089] The adhesive structure of this embodiment can be suitably manufactured using the manufacturing method described above. Furthermore, the adhesive structure of this embodiment can be suitably manufactured using the surface treatment agent described above.

[0090] The specific examples of the first and second vulcanized rubbers are the same as those described above.

[0091] From the same viewpoint as described in the manufacturing method section of this embodiment, the concentration of the aromatic secondary amine antioxidant in the first and second vulcanized rubbers is preferably less than 1% by mass in a region 10 μm deep from the surface in contact with the adhesive layer.

[0092] The polyurethane compounds and / or epoxy compounds contained in the adhesive layer may be derived from polyurethane-based adhesives and / or epoxy-based adhesives used as adhesives.

[0093] The phrase "the surface of vulcanized rubber is chlorinated" means that the rubber molecules present on the surface of vulcanized rubber have chlorine groups.

[0094] In the adhesive structure of this embodiment, the chlorine group is preferably bonded to the carbon atoms of the rubber molecules that form on the surface of the vulcanized rubber.

[0095] In both the first and second vulcanized rubbers, the rubber molecules present on the surface in contact with the adhesive layer preferably have hydroxyl groups. More preferably, the hydroxyl groups are bonded to carbon atoms of the rubber molecules forming on the surface of the vulcanized rubber.

[0096] All of the above embodiments can be achieved, for example, by coating a hypochlorous acid aqueous solution onto a predetermined surface of the vulcanized rubber.

[0097] (tire)

[0098] One embodiment of the present invention provides a tire having the adhesive structure described above. Because the tire of this embodiment uses this adhesive structure, it exhibits excellent fatigue resistance. There are no particular limitations on the portion of the tire in which the adhesive structure is used, and it can be appropriately selected according to the purpose.

[0099] Example

[0100] The present invention is described in more detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0101] (Preparation of vulcanized rubber)

[0102] The compositions listed in Tables 1 and 2 were thoroughly mixed to prepare unvulcanized rubber compositions. The rubber compositions were vulcanized at 165°C for 10 minutes to form a predetermined sheet shape to prepare a pair of vulcanized rubber sheets (first and second vulcanized rubber sheets). Note that the first and second vulcanized rubber sheets used in the various examples are substantially the same, and for convenience, they are referred to as "first" and "second," respectively.

[0103] (Preparation of surface treatment agents)

[0104] Sodium hypochlorite (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) was dissolved in water, and hydrochloric acid (manufactured by Tokyo Chemical Industry Co., Ltd. (TCI)) was added appropriately to prepare an aqueous solution of hypochlorous acid (surface treatment agent), wherein the available chlorine concentration and pH are as listed in Tables 1 and 2. In Comparative Example 1, a 4% ethyl acetate solution of trichloroisocyanuric acid (manufactured by LORD) was prepared as a surface treatment agent instead of the aqueous solution of hypochlorous acid.

[0105] The effective chlorine concentration was measured using a residual chlorine meter manufactured by Kyowa Pure Chemical Industries Co., Ltd., and the pH was measured using a "Calmemo" manufactured by DKK-TOA CORPORATION.

[0106] (Preparation of adhesive structures)

[0107] First and second vulcanized rubber sheets were immersed in a surface treatment agent for 1 minute for surface treatment. After immersion, excess liquid adhering to the surface of the first vulcanized rubber sheet was wiped off, and then, using a 100 μm thick masking tape as a spacer, the adhesives listed in Tables 1 and 2 were applied to the surface of the first vulcanized rubber sheet (applied to a thickness of 100 μm). Next, the coated surface of the first vulcanized rubber sheet was turned upwards, and the second vulcanized rubber sheet was placed on the coated surface. Further, a weight was placed on it to apply pressure to the sheet, and the sheet was left at room temperature for 4 days. In this manner, an adhesive structure in which the adhesive is sandwiched between the first and second vulcanized rubber sheets was prepared.

[0108] For the measurement of peel force, which will be described later, the adhesive structure as described above was prepared using first and second vulcanized rubber sheets, each with a length of 60 mm, a width of 30 mm, and a thickness of 5 mm.

[0109] For the evaluation of fatigue resistance, which will be described later, first and second vulcanized rubber sheets, each 50 mm long, 10 mm wide, and 5 mm thick, were used, with the two sheets offset from each other by 10 mm in the length direction to form a handle part, to prepare the adhesive structure as described above.

[0110] (Measurement of peel force)

[0111] Using a general-purpose testing machine manufactured by INSTRON, T-shaped peel tests were performed on the bonded structures prepared in each example at a tensile speed of 500 mm / min to measure the peel force (N / 25 mm). The results are listed in Tables 1 and 2.

[0112] When the peel force is above 150 N / 25 mm, especially above 220 N / 25 mm, the adhesion can be considered good.

[0113] (Evaluation of fatigue resistance)

[0114] The handle portion of the bonded structure prepared in each embodiment was clamped, and a 50% strain was applied along its length at a frequency of 6 Hz and an ambient temperature of 60°C. Furthermore, the number of strain inputs required for a 1 mm crack to appear was measured. The number of inputs in Comparative Example 1 was set to 100, thus exponentializing the number of inputs in each embodiment. The results are listed in Tables 1 and 2. A larger exponent value indicates better fatigue resistance.

[0115] Note that in embodiments where the measured peel force is less than 150 N / 25 mm, fatigue resistance cannot be evaluated because the sheet is easy to peel.

[0116]

[0117]

[0118] *1 Carbon black: LS-HAF, iodine adsorption capacity 87mg / g, DBP 74ml / 100g

[0119] *2. Vulcanization accelerator: "NOCCELER CZ-G" manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0120] *3 Antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (aromatic secondary amine antioxidant)

[0121] *4 Polyurethane adhesive: “UM880” manufactured by CEMEDINE CO.,LTD.

[0122] *5 Epoxy-based adhesives: "Fusor" manufactured by LORD

[0123] *6 Use a 4% ethyl acetate solution of trichloroisocyanuric acid (manufactured by LORD) instead of an aqueous solution of hypochlorous acid.

[0124] Based on Tables 1 and 2, it can be understood that, compared with the comparative examples, the examples using an aqueous solution of hypochlorous acid with a pH value of 2 or higher and 7 or lower and an effective chlorine concentration of 100 ppm or higher and 13000 ppm or lower as a surface treatment agent for vulcanized rubber can achieve good fatigue resistance, while achieving strong adhesion between vulcanized rubbers via an adhesive.

[0125] Furthermore, as can be understood from the comparison of Examples 4, 6 and 7, both peel strength and fatigue resistance are improved as the concentration of the predetermined antioxidant in the first and second vulcanized rubber decreases.

[0126] Industrial availability

[0127] According to the present invention, a vulcanized rubber surface treatment agent can be provided, which can achieve strong adhesion between vulcanized rubbers without heating and has little impact on rubber deterioration.

[0128] Furthermore, according to the present invention, a method for manufacturing an adhesive structure can be provided, wherein the adhesive structure in which vulcanized rubber is firmly bonded to each other can be manufactured without heating.

[0129] Furthermore, according to the present invention, an adhesive structure with excellent fatigue resistance can be provided, wherein vulcanized rubber is firmly bonded to each other, and a tire having the adhesive structure can be provided.

Claims

1. A method of adhering vulcanized rubbers to each other, using a vulcanized rubber surface treatment agent, which is an aqueous hypochlorous acid solution having a pH of 2 or more and 7 or less and an effective chlorine concentration of 100 ppm or more and 13,000 ppm or less.

2. The method of adhering vulcanized rubbers to each other according to claim 1, wherein the aqueous hypochlorous acid solution has a pH of 4 or more and 7 or less.

3. A manufacturing method of an adhered structure, which is a method for obtaining an adhered structure in which a first vulcanized rubber and a second vulcanized rubber are adhered to each other, the method comprising: a first coating step of coating an aqueous hypochlorous acid solution having a pH of 2 or more and 7 or less and an effective chlorine concentration of 100 ppm or more and 13,000 ppm or less on a surface of the first vulcanized rubber, a second coating step of coating an adhesive on a surface of the aqueous hypochlorous acid solution coated in the first coating step, and an adhering step of adhering the first vulcanized rubber and the second vulcanized rubber to each other via the aqueous hypochlorous acid solution coated in the first coating step and the adhesive coated in the second coating step.

4. The manufacturing method of an adhered structure according to claim 3, wherein a concentration of an aromatic secondary amine-based age resistor in a region of a depth of 10 μm from a surface in contact with the adhesive in the first vulcanized rubber and the second vulcanized rubber is 1 mass% or less.

5. The manufacturing method of an adhered structure according to claim 3 or 4, wherein the adhesive is either one or both of a polyurethane-based adhesive and an epoxy-based adhesive.

6. An adhered structure manufactured by the manufacturing method according to any one of claims 3 to 5, in which a first vulcanized rubber and a second vulcanized rubber are adhered to each other via an adhesive layer, wherein the adhesive layer contains either one or both of a polyurethane compound and an epoxy compound, and at least a part of a surface of the first vulcanized rubber and the second vulcanized rubber in contact with the adhesive layer is chlorinated.

7. The adhered structure according to claim 6, wherein in the first vulcanized rubber and the second vulcanized rubber, a rubber molecule present on a surface in contact with the adhesive layer has a hydroxyl group, and the hydroxyl group is bonded to a carbon atom forming the rubber molecule.

8. The adhered structure according to claim 6, wherein a concentration of an aromatic secondary amine-based age resistor in a region of a depth of 10 μm from a surface in contact with the adhesive layer in the first vulcanized rubber and the second vulcanized rubber is 1 mass% or less.

9. A tire comprising the adhered structure according to any one of claims 6 to 8. ​ ​ ​ ​ ​

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