Hydrophobic polymer dispersion, method for producing cross-linked fibers, method for producing structures, and method for producing rubber articles

Abstract

The present invention provides a hydrophobic polymer dispersion, a method for producing cross-linked fibers, and a method for producing rubber articles, which enable the simple repair of microscopic defects and / or cracks on the surface of rubber to be treated, as well as the reinforcement of areas with low strength, without requiring heating and / or pressurization. [Solution] A hydrophobic polymer dispersion comprising a hydrophobic polymer having double bonds in its polymer chains, a crosslinking agent having thiol groups, a curing agent, and water; and a method for producing a fiber having a crosslinked structure, comprising a spinning step of spinning the hydrophobic polymer dispersion comprising a hydrophobic polymer having double bonds in its polymer chains, a crosslinking agent having thiol groups, a curing agent, and water by electrospinning, and a crosslinking step of reacting the crosslinking agent contained in the fiber spun by the spinning step; a method for producing a fiber having a crosslinked structure; a method for producing a structure; and a method for producing a rubber article using the polymer dispersion and the method for producing the fiber.

Description

Technical Field

[0001] The present invention relates to a hydrophobic polymer dispersion, a method for producing a fiber having a crosslinked structure, a method for producing a structure, and a method for producing a rubber article. Background Art

[0002] In recent years, in connection with global movements toward carbon dioxide emission regulation accompanying energy-saving social demands and growing interest in environmental issues, questioning of mass consumption of consumables has been raised in various industrial fields. In order to suppress such mass consumption of consumables, convenient methods for repairing and restoring consumables are required.

[0003] In particular, rubber articles such as tires and hoses, including vulcanized rubber, require a heating step and / or a pressurizing step for processing, and also require equipment for such steps. Therefore, there is a demand for methods that can easily repair minute defects and / or cracks, or reinforce locations with locally low strength.

[0004] On the other hand, in the field of materials, new fiber materials derived from polymers, which have fine structures and are easy to produce, have been developed and are attracting attention.

[0005] Regarding a method for repairing an article, Patent Document 1 discloses a tire processing method, in which a sheet-like functional resin having a melting point or glass transition temperature of 120°C or lower is placed on the surface of a vulcanized tire, and hot-pressed to form a functional resin layer on the tire surface.

[0006] Also, Patent Document 2 discloses a method for repairing a dent on the surface of an article, wherein a first metal powder having a first melting temperature and a second metal powder having a second melting temperature lower than the first melting temperature are respectively filled into the dent while adjusting the temperature while applying appropriate pressure, and then cooled.

[0007] On the other hand, regarding a method for manufacturing new fiber materials, Patent Document 3 discloses a method for manufacturing a fiber molded article of a polymer resin containing an alicyclic structure, which includes a step of electrospinning a polymer solution as a spinning material, wherein the polymer solution contains a low dielectric constant solvent which is an alicyclic hydrocarbon with a relative dielectric constant of less than 25 and a high dielectric constant solvent which has a relative dielectric constant of 25 or more, and the high dielectric constant solvent is dispersed in the solution in the form of particles, and the number average particle diameter is 40 μm or less. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2017-193087 [Patent Document 2] Japanese Patent Publication No. 2001-115857 [Patent Document 3] Japanese Patent Publication No. 2017-160583 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the methods described in Patent Documents 1 and 2 require processes such as heat and pressure treatment. Heat and pressure treatment may alter the physical properties of rubber, which poses a safety problem, especially for rubber products such as tires. Therefore, there was room for improvement to create a simpler method.

[0010] Therefore, the object of the present invention is to provide a hydrophobic polymer dispersion, a method for producing cross-linked fibers, a method for producing a structure, and a method for producing a rubber article that can easily repair microscopic defects and / or cracks on the surface of a rubber to be treated, and reinforce areas with partially low strength, without requiring heating and / or pressurization. [Means for solving the problem]

[0011] In other words, the gist of the present invention that solves the above problems is as follows.

[0012] [1] A hydrophobic polymer having double bonds in its polymer chain, A crosslinking agent having a thiol group, Hardener and Water and A hydrophobic polymer dispersion characterized by containing the following:

[0013] [2] The hydrophobic polymer dispersion according to [1], further comprising an organic solvent.

[0014] [3] The hydrophobic polymer dispersion according to [1] or [2], wherein the crosslinking agent has two or more thiol groups.

[0015] [4] A hydrophobic polymer dispersion according to any one of [1] to [3], wherein the hydrophobic polymer comprises at least one selected from natural rubber latex, SBR latex, BR latex, NBR latex, CR latex, and EPDM latex.

[0016] [5] The hydrophobic polymer dispersion according to any one of [1] to [4], wherein the curing agent is a curing agent whose curing is induced by light irradiation or heating.

[0017] [6] A method for manufacturing rubber articles, A step of applying a hydrophobic polymer dispersion described in any of [1] to [5] to at least a portion of the surface of the rubber to be treated, A crosslinking step is to crosslink the hydrophobic polymer dispersion to which the applied solution has been transferred. A method for manufacturing rubber articles, characterized by including

[0018] [7] The rubber article is a tire or a rubber hose, the method for manufacturing a rubber article as described in [6].

[0019] [8] A method for producing a fiber having a crosslinked structure, A spinning step comprising spinning using an electrostatic spinning method with a hydrophobic polymer dispersion described in any of [1] to [5], and extruding the fiber body, a crosslinking step of reacting a crosslinking agent contained in the fibrous body; and A method for producing a fiber having a crosslinked structure, comprising:

[0020] [9] The method for producing a fiber having a crosslinked structure according to [8], wherein a diameter of the fibrous body is 100 µm or less.

[0021]

[10] A method for producing a structure, comprising: A method for producing a structure, comprising a processing step of forming a fiber having a crosslinked structure obtained by the production method according to [8] or [9] into a nonwoven fabric shape.

[0022]

[11] A method for producing a rubber article, comprising: a spinning step of spinning by an electrostatic spinning method using the hydrophobic polymer dispersion according to any one of [1] to [5], and obtaining a fibrous body by discharging; a laminating step of laminating the fibrous body on at least a part of a surface of a rubber to be treated; and after the laminating step, a crosslinking step of reacting a crosslinking agent contained in the fibrous body; and A method for producing a rubber article, comprising:

[0023]

[12] The method for producing a rubber article according to

[11] , wherein in the laminating step, the fibrous body discharged in the spinning step is directly laminated on a surface of the rubber to be treated.

[0024]

[13] The method for producing a rubber article according to

[11] or

[12] , wherein a diameter of the fibrous body is 100 µm or less.

[0025]

[14] The method for producing a rubber article according to any one of

[11] to

[13] , wherein the rubber article is a tire or a rubber hose. Effects of the Invention

[0026] According to the present invention, it is possible to provide a hydrophobic polymer dispersion, a method for producing cross-linked fibers, a method for producing a structure, and a method for producing a rubber article, which can easily repair microscopic defects and / or cracks on the surface of a rubber to be treated, and reinforce areas with partially low strength, without requiring heating and / or pressurization. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below. However, this description is for illustrative purposes only and does not limit the present invention in any way.

[0028] The compounds described herein may be derived in part or in whole from fossil resources, from biological resources such as plant resources, or from recycled resources such as used tires. They may also be derived from a mixture of two or more of fossil resources, biological resources, or recycled resources.

[0029] <Hydrophobic polymer dispersion> A hydrophobic polymer dispersion according to one embodiment of the present invention (hereinafter sometimes referred to as "the hydrophobic polymer dispersion of this embodiment") comprises a hydrophobic polymer having double bonds in its polymer chain, a crosslinking agent having thiol groups, a curing agent, and water.

[0030] As described later, the hydrophobic polymer dispersion of this embodiment can be applied to at least a portion of the surface of the rubber to be treated in the application step, or laminated as a fiber extruded by electrospinning in the spinning step, and then reacted with a crosslinking agent in the crosslinking step, thereby coating at least a portion of the surface of the rubber to be treated with a polymer or fiber having a crosslinked structure.

[0031] Therefore, the hydrophobic polymer dispersion of this embodiment makes it possible to easily repair microscopic defects and / or cracks on the surface of the rubber to be treated, as well as reinforce areas with low strength, without requiring heating and / or pressurization.

[0032] In this context, "dispersion" refers to a liquid that, when mixed with water and other substances or compositions, disperses in the water without dissolving, thus taking the form of an emulsion.

[0033] First, the components used or potentially used in the hydrophobic polymer dispersion of this embodiment will be described.

[0034] (Hydrophobic polymer) The hydrophobic polymer dispersion of this embodiment contains a hydrophobic polymer having double bonds in its polymer chain. Examples of such hydrophobic polymers include acrylic latex, polyurethane latex, vinyl acetate latex, and rubber latex. In particular, from the viewpoint of affinity with vulcanized rubber, it is preferable to include at least one selected from natural rubber (NR) latex, isoprene rubber (IR) latex, styrene-butadiene rubber (SBR) latex, butadiene rubber (BR) latex, acrylonitrile-butadiene rubber (NBR) latex, chloroprene rubber (CR) latex, and ethylene-propylene rubber (EPDM) latex. The hydrophobic polymer may be used alone or in combination of two or more types.

[0035] In this context, "hydrophobicity" in the context of polymers refers to the property of polymers to disperse in water without dissolving when mixed with water, similar to the definition of dispersions described above, thus taking the form of an emulsion.

[0036] The amount of hydrophobic polymer contained in the hydrophobic polymer dispersion is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. Furthermore, the amount of hydrophobic polymer contained in the hydrophobic polymer dispersion is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By having the hydrophobic polymer content within the above numerical range, it is possible to obtain fibers having a cross-linked structure with sufficient strength. In addition, such fibers can be used to easily repair microscopic defects and / or cracks on the surface of the rubber to be treated, and to reinforce areas with low strength.

[0037] (Crosslinking agent) The hydrophobic polymer dispersion of this embodiment contains a crosslinking agent. A crosslinking agent is a substance that causes crosslinking (chemical bonding) between polymer chains through a reaction. The functional group (hereinafter also referred to as the crosslinkable functional group) of such a crosslinking agent is a thiol group. The number of thiol groups in the crosslinking agent may be one or two or more, but from the viewpoint of crosslinking different polymer chains, it is preferable to have two or more.

[0038] Examples of crosslinking agents having such thiol groups include trimethylolpropane tris(3-mercaptopropionate) [TMMP], dipentaerythritol 3-mercaptopropionate (DPMP), pentaerythritol tetrakis(3-mercaptopropionate) [PEMP], tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), tetraethylene glycol bis(3-mercaptopropionate) [EGMP-4], trimethylolpropane dipropanthol, pentaerythritol tripropanthol, pentaerythritol tetrapropanthol, ethylene glycol bisthiopropionate (EGTP), butanediol bisthiopropionate (BDTP), trimethylolpropane tristhiopropionate (TMTP), and pentaerythritol tetrakisthiopropionate (P Examples include ETP, butanediol bisthioglycolate (BDTG), hexanediol bisthioglycolate (HDTG), trimethylolpropane trithioglycolate (TMTG), pentaerythritol tetrakisthioglycolate (PETG), methylenedithiol, ethylenedithiol, propylenedithiol, butanedithiol, hexanedithiol, benzenedithiol, xylenedithiol, trithioglycerin, mercaptoethyl trithioglycerin, bis(mercaptoethyl) trithioglycerin, trimercaptoethyl trithioglycerin, mercaptopropyl trithioglycerin, bis(mercaptopropyl) trithioglycerin, trimercaptopropyl trithioglycerin, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-dimercaptoethyl-1,4-dithiane, and 2,5-dimercaptopropyl-1,4-dithiane. These crosslinking agents having thiol groups may be used individually or in combination of two or more.

[0039] The amount of crosslinking agent contained in the hydrophobic polymer dispersion is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the amount of crosslinking agent contained in the hydrophobic polymer dispersion is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. By having the crosslinking agent content within the above numerical range, it is possible to obtain fibers having a crosslinked structure with sufficient strength. In addition, such fibers can be used to easily repair microscopic defects and / or cracks on the surface of the rubber being treated, and to reinforce areas with low strength.

[0040] (Hardening agent) The hydrophobic polymer dispersion of this embodiment contains a curing agent. This curing agent can react the hydrophobic polymer with the crosslinking agent in the hydrophobic polymer dispersion of this embodiment. The curing agent is not particularly limited as long as it is a curing agent that induces a curing reaction, but in particular, from the viewpoint of crosslinking polymers, it is preferable that the curing agent is induced by light irradiation or heating. Examples of such curing agents include ultraviolet (UV) curing agents such as photoradical generators, and radical catalysts such as organic peroxides. In this case, the curing agent does not include the crosslinking agent having the thiol group mentioned above.

[0041] Examples of ultraviolet (UV) curing agents (photoradical generators) include intramolecular cleavage type photoradical generators, such as benzoin alkyl ether-based photoradical generators like benzoin ethyl ether, benzoin isobutyl ether, and benzoin isopropyl ether; acetophenone-based photoradical generators like 2,2-diethoxyacetophenone and 4'-phenoxy-2,2-dichloroacetophenone; propiophenone-based photoradical generators like 2-hydroxy-2-methylpropiophenone, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, and 4'-dodecyl-2-hydroxy-2-methylpropiophenone; anthraquinone-based photoradical generators like benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, and 2-ethylanthraquinone and 2-chloroanthraquinone; and acylphosphine oxide-based photoradical generators. Other examples of hydrogen abstraction-type ultraviolet (UV) curing agents (photoradical generators) include benzophenone / amine-based photoradical generators, Michler ketone / benzophenone-based photoradical generators, and thioxanthone / amine-based photoradical generators. In addition, non-extractable photoradical generators can be used to avoid migration of unreacted photoradical generators. Examples of such non-extractable photoradical generators include polymerized acetophenone-based radical generators and benzophenone with an acrylic double bond added. These ultraviolet (UV) curing agents (photoradical generators) can be used individually or in combination of two or more types.

[0042] Examples of thermal radical generators consisting of organic peroxides include t-butyl-2-ethylperoxyhexanoate, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1-di(t-hexylperoxy)cyclohexanone, di-t-butyl peroxide, t-butylcumyl peroxide, 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane, and t-amylperoxy-2-ethylhexanoate. Examples include butylhexanoate, di(2-t-butylperoxyisopropyl)benzene, di(t-butyl)peroxide, benzoyl peroxide 1,1'-di(2-t-butylperoxyisopropyl)benzene, benzoyl peroxide, 1,1'-di(t-butylperoxy)cyclohexane, di(3,5,5-trimethylhexanoyl)peroxide, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, and dicumyl peroxide. Among these, at least one of t-butyl-2-ethylperoxyhexanoate, dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1-di(t-hexylperoxy)cyclohexanone, di-t-butylperoxide, and t-butylcumyl peroxide is preferred. These radical catalysts, consisting of organic peroxides, can be used individually or in combination of two or more. Furthermore, it is possible to use a combination of two or more radical catalysts and ultraviolet (UV) curing agents.

[0043] Furthermore, the hydrophobic polymer dispersion used in the present invention may contain, in addition to the curing agent, other radical generating agents, such as radical generating agents for promoting crosslinking between polymers. When using a radical generating agent as a curing agent in combination with other radical generating agents, the same or different types of radical generating agents required for activation may be used together.

[0044] The amount of curing agent contained in the hydrophobic polymer dispersion is preferably 0.05% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the amount of curing agent contained in the hydrophobic polymer dispersion is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less. By having the curing agent content within the above numerical range, it is possible to obtain fibers having a cross-linked structure with sufficient strength. In addition, such fibers can be used to easily repair microscopic defects and / or cracks on the surface of the rubber being treated, and to reinforce areas with partially low strength.

[0045] The crosslinking agent and / or curing agent may be added directly to the hydrophobic polymer dispersion, or a solution of the crosslinking agent and / or curing agent in a solvent that dissolves it may be added to the hydrophobic polymer dispersion beforehand. Furthermore, a surfactant may be added to facilitate the impregnation of the crosslinking agent and / or curing agent into the hydrophobic polymer dispersion. In other words, the hydrophobic polymer dispersion of this embodiment may contain a surfactant. Examples of surfactants include sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate, sodium dodecylnaphthalenesulfonate, sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene polyoxypropylene alkyl ether sulfate, polyoxyethylene lauryl ether, polyoxyethylene alkylene alkyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tripenzylphenyl ether, sorbitan monolaurate, sorbitan monostearate, and sorbitan tristearate.

[0046] (water) The hydrophobic polymer dispersion contains water to disperse the hydrophobic polymer and form an emulsion. The water content is not particularly limited as long as it is sufficient to adequately disperse the hydrophobic polymer, but may be, for example, 50 to 95% by mass.

[0047] (organic solvent) Furthermore, the hydrophobic polymer dispersion of this embodiment preferably contains an organic solvent as a solvent for dissolving the crosslinking agent and curing agent dispersed in water and impregnating them into the hydrophobic polymer. Examples of organic solvents include benzene, toluene, xylene, chloroform, ethyl acetate, butyl acetate, and methyl ethyl ketone (MEK), which are water-insoluble solvents that do not mix with water.

[0048] (Other ingredients) In addition to those described above, the hydrophobic polymer dispersion of this embodiment may contain, as appropriate, crosslinking accelerators (vulcanization accelerators), antioxidants, process oils, scorch inhibitors, viscosity modifiers, zinc oxide, stearic acid, and other compounding agents commonly used in the rubber industry, selected within the scope that does not depart from the objectives of the present invention. Commercially available products can be suitably used as these compounding agents.

[0049] <Method for manufacturing fibers having a cross-linked structure> Furthermore, another embodiment of the present invention relates to a method for producing fibers having a cross-linked structure (hereinafter sometimes referred to as "the method for producing fibers of this embodiment").

[0050] The method for producing fibers according to this embodiment is characterized by comprising a spinning step, in which the above-mentioned hydrophobic polymer dispersion is spun by electrospinning and a fibrous body is extruded, and a crosslinking step, in which a crosslinking agent contained in the fibrous body obtained in the spinning step is reacted.

[0051] (Spinning process) In the fiber manufacturing method of this embodiment, the above-mentioned hydrophobic polymer dispersion is spun by electrospinning as a spinning step, and the fiber body is extruded. The spinning method and apparatus used in the electrospinning step can be any method and apparatus commonly used in electrospinning without any particular limitations.

[0052] As a specific example of the spinning process, a hydrophobic polymer dispersion is first extruded at a constant speed from a syringe and supplied to a spinning nozzle. A high voltage is applied to this spinning nozzle from a high-voltage power supply, which charges the supplied hydrophobic polymer dispersion. Next, the hydrophobic polymer dispersion is discharged from the spinning nozzle and becomes a spiral flow due to air resistance. Then, the solvent contained in the discharged hydrophobic polymer dispersion gradually evaporates as it is spun into fine fibers, forming (laminating) the fibrous material on the surface of a rotating disc (collector) located at the tip of the spinning nozzle.

[0053] The conditions for spinning using a hydrophobic polymer dispersion in electrospinning are not particularly limited, but for example, the optimal conditions can be selected from a spray flow rate of 10 to 300 mL / hour, an applied voltage of 15 to 50 kV, and a distance of 5 to 40 cm from the spinning nozzle to the collector. The above method and apparatus are described in detail, for example, in Japanese Patent Publication No. 2023-019599. The diameter of the fiber obtained through the spinning process is preferably 100 μm or less, more preferably 0.01 to 100 μm, and even more preferably 0.1 to 10 μm. By having the fiber diameter within the above numerical range, it is possible to obtain fibers with sufficient strength after the crosslinking process. Furthermore, fibers having such a crosslinked structure can be used to easily repair microscopic defects and / or cracks on the surface of the rubber being treated, and to reinforce areas with low strength.

[0054] (Crosslinking process) Furthermore, in the fiber manufacturing method of this embodiment, the crosslinking step involves reacting the crosslinking agent contained in the fiber obtained in the spinning step. In this way, a fiber having a crosslinked structure is obtained. The trigger and reaction conditions for the crosslinking reaction used in the crosslinking step can be appropriately set in accordance with the chemical structure of the crosslinking agent and curing agent and the reaction conditions, etc.

[0055] <Method for manufacturing the structure> Furthermore, other embodiments of the present invention relate to a method for manufacturing a structure (hereinafter sometimes referred to as "the method for manufacturing a structure of this embodiment").

[0056] The manufacturing method of the structure of this embodiment is characterized by including a processing step of processing the fibers having a cross-linked structure obtained by the above manufacturing method into a nonwoven fabric.

[0057] (Processing process) The processing step for transforming fibers having a cross-linked structure into a nonwoven fabric can be any manufacturing method commonly used for the production of nonwoven fabrics, without any particular limitations.

[0058] Specifically, methods for forming a web (fleece) from cross-linked fibers include the dry-laid method, the wet-laid method, the spunbond method, and the meltblown method. Methods for bonding the web (fleece) include the thermal bond method, the chemical bond method, the needle punch method, and the water entanglement method.

[0059] By manufacturing such a structure, fibers having a cross-linked structure can be processed into a desired shape, thereby enabling the easy repair of microscopic defects and / or cracks on the surface of the rubber being treated, as well as the reinforcement of areas with low strength. Furthermore, the structure may be subjected to further processing after the manufacturing process. Such processing methods are not particularly limited; in addition to cutting the nonwoven fabric structure to the desired size, for example, multiple nonwoven fabric structures may be stacked to form a roughly rectangular parallelepiped, or the nonwoven fabric structure may be rolled up to form a roughly cylindrical shape.

[0060] <Manufacturing method for rubber articles A> Furthermore, another embodiment of the present invention relates to a method for manufacturing rubber articles (hereinafter sometimes referred to as "Method A for manufacturing rubber articles of this embodiment").

[0061] The rubber article manufacturing method A of this embodiment is characterized by including an application step of applying the above-described hydrophobic polymer dispersion to at least a portion of the surface of the rubber to be treated, and a crosslinking step of crosslinking the applied hydrophobic polymer dispersion. In other words, the rubber article manufacturing method A of this embodiment uses the rubber to be treated and processes the rubber in a predetermined manner to manufacture a rubber article.

[0062] (Granting process) In the rubber article manufacturing method A of this embodiment, the hydrophobic polymer dispersion described above is applied to at least a portion of the surface of the rubber to be treated as an application step. That is, in the application step of the rubber article manufacturing method A of this embodiment, the hydrophobic polymer dispersion is applied directly to at least a portion of the surface of the rubber to be treated without going through the spinning step. In this context, "application" includes coating or laminating a hydrophobic polymer dispersion onto at least a portion of the surface of the rubber to be treated.

[0063] Furthermore, in this case, "at least a portion of the surface of the rubber to be treated" typically refers to the surface of the rubber to be treated where particularly fine defects and / or cracks have occurred, but it may also refer to the surface of areas where the strength is partially low in the rubber to be treated after manufacturing.

[0064] (Crosslinking process) Furthermore, in the rubber article manufacturing method A of this embodiment, the hydrophobic polymer dispersion applied in the application step is crosslinked as a crosslinking step. In this way, a rubber article is obtained. Specifically, by crosslinking the hydrophobic polymer dispersion (reacting with a crosslinking agent) in the crosslinking step after the application step, it becomes possible to coat at least a part of the surface of the rubber to be treated with a polymer having a crosslinked structure. As a result, without requiring heating and / or pressurization, a rubber article can be obtained in which microscopic defects and / or cracks on the surface of the rubber to be treated are repaired, and areas with partially low strength are reinforced. The trigger and reaction conditions for the crosslinking reaction used in the crosslinking step can be appropriately set in accordance with the chemical structure of the crosslinking agent and curing agent and the reaction conditions, etc.

[0065] <Manufacturing method for rubber articles B> Furthermore, a method for manufacturing rubber articles according to a different embodiment (hereinafter sometimes referred to as "Method B for Manufacturing Rubber Articles of this Embodiment") is characterized by comprising: a spinning step in which the above-described hydrophobic polymer dispersion is used to spin fibers by electrospinning and extruded; a lamination step in which the fibers are laminated onto at least a portion of the surface of the rubber to be treated; and a crosslinking step in which a crosslinking agent contained in the fibers is reacted after the lamination step. In other words, Method B for Manufacturing Rubber Articles of this Embodiment also uses the rubber to be treated and processes the rubber to be treated in a predetermined manner to manufacture a rubber article.

[0066] (Spinning process) In manufacturing method B of this embodiment, the spinning step involves spinning using the hydrophobic polymer dispersion described above by electrospinning, and then extruding the fibers. This spinning step is the same as the spinning step of the fiber manufacturing method of this embodiment, and that description will be applied accordingly.

[0067] (Lamination process) In the rubber article manufacturing method B of this embodiment, as a lamination step, the fibrous material obtained by the spinning step is laminated onto at least a portion of the surface of the rubber to be processed. In this rubber article manufacturing method B, the fibrous material spun by electrospinning is laminated onto at least a portion of the surface of the rubber to be processed.

[0068] Furthermore, in the lamination process, it is preferable to directly laminate the fibers extruded in the spinning process onto the surface of the rubber to be processed (i.e., to directly laminate the fibers extruded in the spinning process of the electrospinning method described above onto the surface of the rubber to be processed, rather than onto the surface of the rotating disc). By laminating in this way, minute defects and / or cracks on the surface of the rubber to be processed, as well as depressions such as areas where the rubber is thin (low strength), are filled in by the fibers (due to the nature of the electrospinning method, the extruded fibers tend to accumulate in such gaps), and the surface of the final manufactured rubber article becomes smooth.

[0069] (Crosslinking process) Furthermore, in the rubber article manufacturing method B of this embodiment, after the lamination step, a crosslinking step is performed in which the crosslinking agent contained in the fiber is reacted. In this way, a rubber article is obtained. Specifically, by manufacturing the rubber article in this order, it becomes possible to coat at least a part of the surface of the rubber to be treated with fibers having a crosslinked structure, and as a result, a rubber article can be obtained in which microscopic defects and / or cracks on the surface of the rubber to be treated are repaired, and areas with partially low strength are reinforced, without requiring heating and / or pressurization. The trigger and reaction conditions for the crosslinking reaction used in the crosslinking step can be appropriately set in accordance with the chemical structure of the crosslinking agent and curing agent and the reaction conditions, etc.

[0070] Examples of rubber articles (and rubber to be processed) manufactured using the above manufacturing method include tires, hoses, belts (conveyor belts), rubber tracks, insulators or sealing materials, vibration-damping rubber or seismic isolation rubber, balls for ball games, rubber gloves, etc. In particular, among the above rubber articles (and rubber to be processed), tires or hoses are preferred as they require high strength. [Examples]

[0071] The present invention will be described in more detail below with reference to examples, but these examples are for illustrative purposes only and do not limit the present invention in any way.

[0072] (Preparation of crosslinking agent solution) First, crosslinking agent preparation solutions for Samples No. 1 to No. 4 were prepared by dissolving trimethylolpropanetris (3-mercaptopropionate) [TMMP] (manufactured by Sakai Chemical Industry Co., Ltd.) as a crosslinking agent, polyoxyethylene distyrenated phenyl ether (Emulgen A-500, manufactured by Kao Corporation) as a surfactant, and 1-hydroxycyclohexyl phenyl ketone (manufactured by Tokyo Chemical Industry Co., Ltd.) as a UV curing agent, all in toluene (manufactured by Kanto Chemical Co., Ltd.), which is an organic solvent. The proportions of each sample in the crosslinking agent preparation solution are shown in Table 1 below. [Table 1]

[0073] (Preparation of hydrophobic polymer dispersions) Next, a hydrophobic polymer dispersion was prepared by dispersing natural rubber latex (solids content: 40% by mass) (manufactured by GOLDEN HOPE LATEX) as a hydrophobic polymer, a 6% by mass aqueous polyethylene oxide (PEO) solution (molecular weight: 2 million, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a viscosity modifier, and crosslinking agent preparation solutions No. 1 to No. 4 in water. The proportions of the hydrophobic polymer dispersion used in each example are shown in Table 2 below.

[0074] (Electrospun yarn) For each example, the hydrophobic polymer dispersion was filled into a syringe, then wrapped in aluminum foil on a 10 cm diameter rotating disc (manufactured by MEC Corporation), and spun into fibers by spraying under the following conditions: rotation speed 500 rpm, oscillation width 10 cm / 10 sec, applied voltage 20 kV, coating speed 1.5 ml / min, distance 20 cm, and for 60 minutes.

[0075] (Crosslinking reaction) For each example, the fibrous material was irradiated with UV light using a UV irradiation device (manufactured by iGraphics Co., Ltd.) to induce a cross-linking reaction. The irradiation conditions were 1500-2000 mW / cm using UV light with a wavelength of 365 nm. 2 Ultraviolet irradiation was performed under the following conditions.

[0076] <Tensile Test> Tensile tests were conducted to confirm the elastic modulus and breaking strength of the cross-linked fibers in each example. The tensile tests were performed under the following conditions. The cross-linked fibers in each example were processed into strips 50 mm long and 10 mm wide and used as samples. The measurement conditions were set to a chuck distance of 10 mm and a tensile speed of 10 mm / min, and the film thickness was measured using calipers. The test results are shown in Table 2.

[0077] [Table 2]

[0078] The results shown in Table 2 indicate that the crosslinked fibers of Examples 1 to 4 exhibit high elastic modulus and high tensile strength. Furthermore, Examples 3 and 4, which contain high amounts of crosslinking agent and UV curing agent, exhibit particularly high tensile strength.

[0079] In other words, by using a hydrophobic polymer dispersion according to the present invention, it is possible to obtain fibers having a cross-linked structure with sufficient strength, and by using these fibers, it is possible to solve the problem of easily repairing microscopic defects and / or cracks on the surface of the rubber to be treated, and reinforcing areas with low strength, without requiring heating and / or pressurization. [Industrial applicability]

[0080] According to the present invention, it is possible to provide a hydrophobic polymer dispersion, a method for producing cross-linked fibers, a method for producing a structure, and a method for producing a rubber article, which can easily repair microscopic defects and / or cracks on the surface of a rubber to be treated, and reinforce areas with partially low strength, without requiring heating and / or pressurization.

Claims

1. A hydrophobic polymer having double bonds in its polymer chain, A crosslinking agent having a thiol group, Hardener and Water and A hydrophobic polymer dispersion characterized by containing the following:

2. Furthermore, the hydrophobic polymer dispersion according to claim 1, comprising an organic solvent.

3. The hydrophobic polymer dispersion according to claim 1, wherein the number of thiol groups in the crosslinking agent is two or more.

4. The hydrophobic polymer dispersion according to claim 1, wherein the hydrophobic polymer comprises at least one selected from natural rubber latex, SBR latex, BR latex, NBR latex, CR latex, and EPDM latex.

5. The hydrophobic polymer dispersion according to claim 1, wherein the curing agent is a curing agent whose curing is induced by light irradiation or heating.

6. A method for manufacturing rubber articles, A step of applying the hydrophobic polymer dispersion described in claim 1 to at least a portion of the surface of the rubber to be treated, A crosslinking step is to crosslink the hydrophobic polymer dispersion to which the applied solution has been transferred. A method for manufacturing rubber articles, characterized by including

7. The method for manufacturing a rubber article according to claim 6, wherein the rubber article is a tire or a rubber hose.

8. A method for producing fibers having a crosslinked structure, A spinning step comprising spinning using the hydrophobic polymer dispersion described in claim 1 by electrospinning and extruding a fiber body, A crosslinking step involves reacting the crosslinking agent contained in the aforementioned fiber, A method for producing a fiber having a crosslinked structure, characterized by including the following:

9. A method for producing a fiber having a crosslinked structure according to claim 8, wherein the diameter of the fiber is 100 μm or less.

10. A method for manufacturing a structure, A method for manufacturing a structure, characterized by including a processing step of processing a fiber having a crosslinked structure obtained by the manufacturing method described in claim 8 into a nonwoven fabric.

11. A method for manufacturing rubber articles, A spinning step comprising spinning using the hydrophobic polymer dispersion described in claim 1 by electrospinning and extruding a fiber body, A lamination step of laminating the aforementioned fibrous material onto at least a portion of the surface of the rubber to be processed, Following the lamination step, a crosslinking step is performed in which the crosslinking agent contained in the fiber is reacted. A method for manufacturing rubber articles, characterized by including

12. The method for manufacturing a rubber article according to claim 11, wherein in the lamination step, the fibrous material extruded in the spinning step is directly laminated onto the surface of the rubber to be processed.

13. The method for manufacturing a rubber article according to claim 11, wherein the diameter of the fiber is 100 μm or less.

14. The method for manufacturing a rubber article according to claim 11, wherein the rubber article is a tire or a rubber hose.

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