Rubber composition for hose, hose, and method for producing the same

Abstract

To provide a rubber composition for hose, a hose, and a production method therefor, the composition and hose exhibiting superior wire adhesion and tensile strength.SOLUTION: A rubber composition for hose comprises a rubber component including an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic acid ester monomer units, and carboxyl group monomer units; carbon black; a diamine crosslinking agent; and an ethylene-glycidyl (meth)acrylate copolymer. The invention also provides a hose having an inner layer, a reinforcing layer, and an outer layer in this order, wherein the reinforcing layer includes a wire-reinforcing layer subjected to brass plating, the wire-reinforcing layer is adjacent to the outer layer, and the outer layer is a cured product of the rubber composition for hose.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for a hose, a hose, and a method for producing the same. [Background technology]

[0002] BACKGROUND ART It has been known in the past to apply a crosslinkable rubber composition containing a carboxyl group-containing nitrile rubber, a carboxyl group-containing acrylic rubber, and a polyamine-based crosslinking agent to hoses and the like (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 180207 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have studied the rubber composition disclosed in Patent Document 1 and have found that the cured product obtained from the rubber composition may have low adhesion to wire (wire adhesion) and / or low tensile strength.

[0005] Therefore, an object of the present invention is to provide a rubber composition for a hose that has excellent wire adhesion and tensile strength. Another object of the present invention is to provide a hose and a method for manufacturing the same. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0007] [1] A rubber component containing an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic acid ester monomer units, and carboxyl group monomer units; Carbon black and a diamine crosslinker; and an ethylene-glycidyl (meth)acrylate copolymer. [2] The rubber composition for a hose according to [1], wherein the content of the ethylene-glycidyl (meth)acrylate copolymer is 18 to 22 parts by mass per 100 parts by mass of the rubber component. [3] The rubber composition for a hose according to [1] or [2], further comprising a triazine-based compound, the content of the triazine-based compound being 0.2 to 1 part by mass per 100 parts by mass of the rubber component. [4] The rubber composition for a hose according to any one of [1] to [3], further comprising an ether-based plasticizer. [5] The rubber composition for a hose according to [4], wherein the ether-based plasticizer contains dibutyl carbitol adipate. [6] A hose having an inner layer, a reinforcing layer, and an outer layer in this order, wherein the reinforcing layer includes a brass-plated wire reinforcing layer, the wire reinforcing layer is adjacent to the outer layer, and the outer layer is a cured product of the rubber composition for a hose described in any one of [1] to [5]. [7] A method for producing a hose according to [6], by crosslinking an uncrosslinked hose only by primary crosslinking, the hose having an inner layer composition, a reinforcing layer, and an outer layer composition in this order, the reinforcing layer including a brass-plated wire reinforcing layer, the wire reinforcing layer being adjacent to the outer layer composition, and the outer layer composition being the rubber composition for a hose according to any one of [1] to [5]. [Effects of the Invention]

[0008] According to the present invention, a rubber composition for a hose having excellent wire adhesion and tensile strength can be provided. The present invention also provides a hose and a method for manufacturing the same. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a partially cutaway perspective view of one embodiment of a hose of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, each component can be used alone or in combination of two or more types, unless otherwise specified. In this specification, when two or more types of a certain component are used in combination, the "content" of the component means the total content of those two or more types, unless otherwise specified. In the present specification, the method for producing each component is not particularly limited unless otherwise specified, and may be, for example, a conventionally known method. In this specification, the term "(meth)acrylate" refers to a concept that includes acrylate and methacrylate. In this specification, being superior in at least one of wire adhesiveness and tensile strength is also referred to as "being superior in the effects of the present invention."

[0011] [Rubber composition for hoses] The rubber composition for a hose of the present invention will be described below. The rubber composition for a hose of the present invention (the rubber composition of the present invention) is a rubber component containing an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic acid ester monomer units, and carboxy group monomer units; Carbon black and a diamine crosslinker; and an ethylene-glycidyl (meth)acrylate copolymer.

[0012] The reason why the rubber composition of the present invention having the above-described configuration can solve the problems of the present invention is not necessarily clear, but the present inventors speculate as follows. Note that the following speculation does not limit the mechanism by which the effects are obtained. In other words, even if the effects are obtained by a mechanism other than the one described below, it is still included in the scope of the present invention. That is, it is believed that the epoxy groups in the ethylene-glycidyl (meth)acrylate copolymer in the rubber composition of the present invention improve the adhesiveness of the cured product obtained from the rubber composition of the present invention to wire. Also, the inclusion of the ethylene-glycidyl (meth)acrylate copolymer increases the efficiency of the crosslinking reaction between the acrylic rubber and the diamine crosslinking agent, which is believed to improve the tensile strength of the cured product obtained from the rubber composition of the present invention.

[0013] [Rubber component] In the rubber composition of the present invention, the rubber component contains an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic ester monomer units, and carboxy group monomer units.

[0014] [Acrylic rubber] The rubber composition of the present invention contains an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic ester monomer units, and carboxy group monomer units. In this specification, the acrylic rubber is also referred to as a "specific acrylic rubber." The specific acrylic rubber has a carboxy group (—COOH) derived from a carboxy group monomer unit, and the carboxy group can function as a crosslinking site (crosslinking point). The specific acrylic rubber does not include the ethylene-glycidyl (meth)acrylate copolymer described below.

[0015] [Ethylene monomer unit] In the rubber composition of the present invention, the ethylene monomer unit contained in the specific acrylic rubber refers to a repeating unit formed by ethylene (CH2=CH2). The ethylene monomer unit does not include a vinyl acetate monomer unit, an acrylic acid ester monomer unit, or a carboxyl group monomer unit, which will be described later.

[0016] [Vinyl acetate monomer unit] In the rubber composition of the present invention, the vinyl acetate monomer unit contained in the specific acrylic rubber refers to a repeating unit formed by vinyl acetate (CH3COO-CH2=CH2).

[0017] [Acrylate ester monomer unit] In the rubber composition of the present invention, the acrylic acid ester monomer unit contained in the specific acrylic rubber refers to a repeating unit formed by an acrylic acid ester. Examples of acrylic acid esters include alkyl acrylates, and specific examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isobutyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate.

[0018] [Carboxylic acid monomer unit] In the rubber composition of the present invention, the carboxy group monomer unit contained in the specific acrylic rubber refers to a repeating unit formed by a monomer having a carboxy group (—COOH). The carboxy group monomer may further have an α,β-ethylenically unsaturated bond. Examples of the carboxyl group monomer include monocarboxylic acid compounds having an α,β-ethylenically unsaturated bond, such as acrylic acid, methacrylic acid, crotonic acid, and 2-pentenoic acid; Dicarboxylic acid compounds having an α,β-ethylenically unsaturated bond, such as maleic acid, fumaric acid, itaconic acid, and citraconic acid, or acid anhydrides thereof; Examples of the monoester compound include monoester compounds of the above dicarboxylic acid compounds and alcohols. Maleic acid monoesters such as monomethyl maleate, monoethyl maleate, mono-n-propyl maleate, monoisopyr maleate, mono-n-butyl maleate, and monoisobutyl maleate; Fumaric acid monoesters such as monomethyl fumarate, monoethyl fumarate, mono-n-propyl fumarate, monoisopropyl fumarate, mono-n-butyl fumarate; Itaconanoic acid monoesters such as monomethyl itaconate, monoethyl itaconate, and mono-n-propyl itaconate; Examples include citraconic acid monoesters such as mono-n-propyl citraconate, mono-n-butyl citraconate, and monoisobutyl citraconate. The specific acrylic rubber may have carboxy group monomer units in a proportion of, for example, 0.1 to 30% by mass in the specific acrylic rubber.

[0019] (Method of manufacturing specific acrylic rubber) Examples of the method for producing the specific acrylic rubber include a method for producing the specific acrylic rubber by copolymerizing the above-mentioned ethylene, vinyl acetate, acrylic acid ester monomer, and carboxy group monomer unit by a known method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization.

[0020] (Other rubber) The rubber component contained in the rubber composition of the present invention may further contain rubbers other than the specific acrylic rubber (other rubbers). There are no particular limitations on the other rubbers.

[0021] (Specific acrylic rubber content) From the viewpoint of achieving better effects of the present invention, the content of the specific acrylic rubber is preferably 80 to 100 mass % of the total amount of the rubber component including the specific acrylic rubber, and more preferably 100 mass %.

[0022] (Rubber content) The content of the rubber component (all rubber components including the specific acrylic rubber) is preferably 40 to 80% by mass of the total amount of the rubber composition of the present invention, from the viewpoint of achieving better effects of the present invention.

[0023] [Carbon black] The rubber composition of the present invention contains carbon black.

[0024] (Nitrogen adsorption specific surface area) The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 10 to 130 m from the viewpoint of obtaining a more excellent effect of the present invention. 2 / g, and 20 to 50m 2 / g is more preferred. The nitrogen adsorption specific surface area of ​​carbon black can be measured in accordance with JIS K6217-2:2008.

[0025] (Dibutyl phthalate oil absorption) From the viewpoint of achieving superior effects of the present invention, the dibutyl phthalate (DBP) oil absorption of the carbon black is preferably from 10 to 140 ml / 100 g, more preferably from 20 to 130 ml / 100 g, and even more preferably from 40 to 130 ml / 100 g. The DBP oil absorption of carbon black can be measured in accordance with JIS K6217-4:2008.

[0026] (Iodine adsorption amount) From the viewpoint of achieving a superior effect of the present invention, the iodine adsorption amount of carbon black is preferably 10 to 50 mg / g, and more preferably 15 to 50 mg / g. The iodine adsorption amount of carbon black can be measured in accordance with JIS K6217-1:2008.

[0027] (Type of carbon black) From the viewpoint of achieving better effects of the present invention, the carbon black preferably contains at least one selected from the group consisting of SAF, ISAF, HAF, FEF, GPF, and SRF carbon black, more preferably contains at least one selected from the group consisting of FEF, GPF, and SRF carbon black, and even more preferably contains FEF and / or SRF carbon black.

[0028] (Carbon black content) The amount of carbon black is preferably 60 parts by mass or more, and more preferably 70 to 100 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention.

[0029] [Diamine crosslinker] The rubber composition of the present invention contains a diamine crosslinking agent. A diamine crosslinking agent is a compound that has two amino groups (-NH2) in one molecule. The diamine crosslinking agent can react with the carboxyl group of the specific acrylic rubber to crosslink the specific acrylic rubber.

[0030] Examples of diamine crosslinking agents include compounds in which two aminophenyl groups or two aminophenoxy groups are linked via a divalent linking group. The linking group is not particularly limited. Specific examples of diamine crosslinking agents include 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminodiphenyl sulfide, 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)pentane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenylsulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether. Among these, from the viewpoint of achieving better effects of the present invention, the diamine crosslinking agent preferably contains a diamine compound in which two (aminophenoxy)phenyl groups are bonded via an alkylene group, and more preferably contains 2,2-bis[4-(4-aminophenoxy)phenyl]propane. In a diamine compound in which two (aminophenoxy)phenyl groups are bonded via an alkylene group, the alkylene group is not particularly limited and may be either linear or branched. The number of carbon atoms in the alkylene group may be, for example, 1 to 6. The two (aminophenoxy)phenyl groups possessed by the diamine compound each independently may be bonded to any carbon atom of the phenyl group (excluding the carbon atom bonded to the alkylene group), and the amino group (-NH2) may be bonded to any carbon atom of the phenoxy group (excluding the carbon atom bonded to the phenyl group).

[0031] (Diamine crosslinker content) The content of the diamine crosslinking agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5.0 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention.

[0032] [Ethylene-glycidyl (meth)acrylate copolymer] The rubber composition of the present invention contains an ethylene-glycidyl (meth)acrylate copolymer. The ethylene-glycidyl (meth)acrylate copolymer is a copolymer having ethylene monomer units and glycidyl (meth)acrylate monomer units. The ethylene-glycidyl (meth)acrylate copolymer has a glycidyl group (a group in which a CH2 group is bonded to an epoxy group) derived from the glycidyl (meth)acrylate monomer. In this specification, the ethylene-glycidyl (meth)acrylate copolymer is also referred to as a "specific glycidyl group-containing copolymer." The specific glycidyl group-containing copolymer can function as an adhesive component for the wire. The specific glycidyl group-containing copolymer does not include the above-mentioned specific acrylic rubber.

[0033] [ethylene] In the rubber composition of the present invention, the specific glycidyl group-containing copolymer has a repeating unit (ethylene monomer unit) formed by ethylene (monomer CH═CH). The ethylene monomer unit does not include a glycidyl (meth)acrylate monomer unit or a (meth)acrylic acid ester monomer unit, which will be described later. (Ethylene monomer unit content) The content of the ethylene monomer unit can be set to 50 to 70% by mass of the total amount of the specific glycidyl group-containing copolymer. In this specification, the content of each monomer unit contained in the specific glycidyl group-containing copolymer is 1 It can be measured by H-NMR.

[0034] [Glycidyl (meth)acrylate] In the rubber composition of the present invention, the specific acrylic rubber has repeating units (glycidyl (meth)acrylate monomer units) formed by glycidyl acrylate and / or glycidyl methacrylate as monomers. The glycidyl (meth)acrylate preferably contains glycidyl methacrylate (structure shown below) from the viewpoint of achieving better effects of the present invention. [ka] (Glycidyl (meth)acrylate monomer unit content) The content of the glycidyl (meth)acrylate monomer unit is preferably 1 to 10% by mass based on the total amount of the specific glycidyl group-containing copolymer, from the viewpoint of achieving better effects of the present invention.

[0035] ((Meth)acrylic acid ester monomer unit) In a preferred embodiment, the specific glycidyl group-containing copolymer further contains repeating units of (meth)acrylic acid ester ((meth)acrylic acid ester monomer units). The (meth)acrylic acid ester monomer units exclude glycidyl (meth)acrylate monomer units. Examples of (meth)acrylic acid esters include alkyl acrylates, and specific examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, isobutyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, and 2-ethylhexyl acrylate. When the specific glycidyl group-containing copolymer further has a repeating unit of a (meth)acrylic acid ester, the (meth)acrylic acid ester preferably contains methyl acrylate, from the viewpoint of achieving better effects of the present invention. ((Meth)acrylic acid ester monomer unit content) The content of the (meth)acrylic acid ester monomer unit can be set to 0 to 49% by mass in the total amount of the specific glycidyl group-containing copolymer.

[0036] When the specific glycidyl group-containing copolymer further contains repeating units of (meth)acrylic acid ester, the content of ethylene monomer units can be 50% by mass or more and 70% by mass or less of the total amount of the specific glycidyl group-containing copolymer. In this case, the content of glycidyl (meth)acrylate monomer units is preferably 1 to 10% by mass of the total amount of the specific glycidyl group-containing copolymer. In this case, the content of (meth)acrylic acid ester monomer units can be more than 0% by mass and 49% by mass or less of the total amount of the specific glycidyl group-containing copolymer.

[0037] From the viewpoint of achieving better effects of the present invention, the specific glycidyl group-containing copolymer preferably contains an ethylene-glycidyl methacrylate copolymer, and more preferably contains an ethylene-glycidyl methacrylate-methyl acrylate copolymer.

[0038] (Ethylene-glycidyl (meth)acrylate copolymer content) The content of the ethylene-glycidyl (meth)acrylate copolymer is preferably 5 to 30 parts by mass, more preferably 18 to 22 parts by mass, per 100 parts by mass of the rubber component, from the viewpoints of achieving better effects of the present invention, excellent elongation at break of the resulting cured product, and enabling the hardness of the resulting cured product to be in an appropriate range.

[0039] (additives) The rubber composition of the present invention may further contain additives as needed, provided that the object of the present invention is not impaired. Examples of the additives include antioxidants such as 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, processing aids such as stearic acid, primary monoamines, plasticizers, triazine compounds, crosslinking accelerators, etc. The type and content of each additive can be selected appropriately.

[0040] (Triazine compounds) From the viewpoint of achieving superior effects of the present invention, the rubber composition of the present invention preferably further contains a triazine-based compound. A triazine-based compound refers to a compound having a triazine skeleton. The triazine-based compound may further have a sulfur-containing functional group. Examples of the sulfur-containing functional group that the triazine-based compound may further have include a mercapto group.

[0041] Examples of the triazine-based compound include triazine-based compounds having a mercapto group, and specific examples thereof include 2,4,6-trimercapto-s-triazine (a compound represented by the following structure), 2-hexylamino-4,6-dimercaptotriazine, 2-diethylamino-4,6-dimercaptotriazine, 2-cyclohexylamino-4,6-dimercaptotriazine, 2-dibutylamino-4,6-dimercaptotriazine, 2-anilino-4,6-dimercaptotriazine, and 2-phenylamino-4,6-dimercaptotriazine.

[0042] [ka]

[0043] From the viewpoints of achieving better effects of the present invention, excellent elongation at break of the resulting cured product, and enabling the hardness of the resulting cured product to be within an appropriate range, the triazine-based compound preferably contains a triazine-based compound having a mercapto group, and more preferably contains 2,4,6-trimercapto-s-triazine.

[0044] (Triazine compound content) When the rubber composition of the present invention further contains a triazine-based compound, the content of the triazine-based compound is preferably 0.1 to 2 parts by mass per 100 parts by mass of the rubber component, from the viewpoints of achieving better effects of the present invention, providing excellent elongation at break of the resulting cured product, allowing the hardness of the resulting cured product to be in an appropriate range, and not inhibiting the crosslinking reaction between the acrylic rubber and the diamine crosslinking agent.

[0045] (plasticizer) In one preferred embodiment, the rubber composition of the present invention further contains a plasticizer. When the rubber composition of the present invention further contains a plasticizer, the plasticizer preferably contains an ether-based plasticizer. The ether-based plasticizer may be any compound that has an ether bond and can soften or plasticize the acrylic rubber. Examples of ether-based plasticizers include compounds in which two carboxy groups of a dicarboxylic acid are each esterified with a monohydroxy compound having one or more ether bonds. In the dicarboxylic acid, the linking group between the two carboxy groups (-COOH) is not particularly limited, and examples thereof include alkylene groups having 1 to 10 carbon atoms. The alkylene group may be either linear or branched. Examples of the dicarboxylic acid include adipic acid.

[0046] When the rubber composition of the present invention further contains an ether-based plasticizer, the ether-based plasticizer preferably contains adipic acid bis(alkoxyalkyl ester), and more preferably contains dibutyl carbitol adipate (e.g., adipic acid bis[2-(2-butoxyethoxy)ethyl] ester). Examples of the "alkoxyalkyl" group in the above-mentioned adipic acid bis(alkoxyalkyl ester) include aliphatic hydrocarbon groups having one or more ether bonds and a total of 6 to 20 carbon atoms, and specific examples thereof include a (butoxyethoxy)ethyl group (C4H9-O-C2H4-O-C2H4-).

[0047] (Plasticizer content) When the rubber composition of the present invention further contains a plasticizer, the content of the plasticizer is preferably 1 to 10 parts by mass, more preferably 3 to 8 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of achieving better effects of the present invention.

[0048] (primary monoamine) In one preferred embodiment, the rubber composition of the present invention further contains a primary monoamine. A primary monoamine refers to a compound having one nitrogen atom in one molecule, with one hydrocarbon group and two hydrogen atoms bonded to the nitrogen atom. Primary monoamines can function as crosslinking retarders for special acrylic rubbers. When the rubber composition of the present invention further contains a primary monoamine, the scorch time of the rubber composition of the present invention can be extended compared to when the rubber composition does not contain a primary monoamine. The hydrocarbon group contained in the primary monoamine is not particularly limited, and examples thereof include alkyl groups. When the rubber composition of the present invention further contains a primary monoamine, examples of the primary monoamine include alkyl monoamines having one alkyl group having 10 to 25 carbon atoms, such as N-dodecylamine, N-hexadecylamine, N-octadecylamine, and N-behenylamine. From the viewpoint of having the effect of a crosslinking retarder (being able to extend the scorch time), the primary monoamine preferably contains an alkyl monoamine having one alkyl group having 10 to 25 carbon atoms, and more preferably contains N-octadecylamine.

[0049] (Primary monoamine content) When the rubber composition of the present invention further contains a primary monoamine, the content of the primary monoamine is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint of having the effect of a crosslinking retarder (being able to extend the scorch time).

[0050] (Method of manufacturing rubber composition) The rubber composition of the present invention can be produced by a conventionally known production method, for example, a method of mixing the above-mentioned components using an internal mixer such as a Banbury mixer or a kneader, a kneading roll machine such as a roll, an extruder, or a twin-screw extruder.

[0051] (cured product) By crosslinking the rubber composition of the present invention, a cured product of the rubber composition of the present invention can be obtained.

[0052] (Crosslinking of rubber composition) The method and conditions for crosslinking the rubber composition of the present invention are not particularly limited. The crosslinking temperature is preferably 150 to 180° C. The crosslinking time can be, for example, 60 minutes or more and 240 minutes or less. Examples of methods for crosslinking the rubber composition of the present invention include steam crosslinking (a method in which the rubber composition is sealed in a high-pressure container and crosslinked in a steam canister), oven crosslinking (a method in which the rubber composition is covered with nylon cloth or the like and crosslinked in a hot air drying oven), press crosslinking, steam crosslinking, and hot water crosslinking. From the viewpoint of productivity, the method for crosslinking the rubber composition of the present invention is preferably steam crosslinking.

[0053] (Primary crosslinking) The rubber composition of the present invention can give a cured product having excellent wire adhesion and tensile strength by only primary crosslinking. Conditions for crosslinking the rubber composition of the present invention by only primary crosslinking include a crosslinking temperature of, for example, 150 to 180° C. and a crosslinking time of, for example, 60 minutes or more and 240 minutes or less. When the rubber composition of the present invention is crosslinked by primary crosslinking under the above conditions, there is no need to carry out secondary crosslinking, which is usually required when crosslinking a rubber composition containing an acrylic rubber.

[0054] The rubber composition of the present invention is a rubber composition for hoses, and specifically, can be used for low-pressure or hydraulic hoses, for example. The rubber composition of the present invention can be applied to, for example, at least one component of a hose. In one preferred embodiment, the rubber composition of the present invention is applied to, for example, an outer layer and / or a layer adjacent to the wire-reinforced layer of a hose.

[0055] [hose] The hose of the present invention is The hose has an inner layer, a reinforcing layer, and an outer layer in this order, wherein the reinforcing layer includes a brass-plated wire reinforcing layer, the wire reinforcing layer is adjacent to the outer layer, and the outer layer is a cured product of the rubber composition for a hose of the present invention. The hose of the present invention has an outer layer made of a cured product of the rubber composition of the present invention, and therefore has excellent wire adhesion and tensile strength.

[0056] The configuration of the hose of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the accompanying drawings. FIG. 1 is a partially cutaway perspective view of one embodiment of the hose of the present invention. In Figure 1, hose 1 is formed in a cylindrical shape and has inner layer 11, reinforcing layer 12 provided on the outside of inner layer 11, and outer layer 13 provided on the outside of reinforcing layer 12. In other words, hose 1 has inner layer 11, reinforcing layer 12, and outer layer 13, in this order. Hose 1 has one inner layer 11, one reinforcing layer 12, and one outer layer 13. Here, "reinforcing layer 12 is one layer" means that reinforcing layer 12 as a whole is one layer. The reinforcing layer 12 includes a brass-plated wire reinforcing layer, and the wire reinforcing layer is adjacent to the outer layer 13. When the reinforcing layer 12 is composed of a single layer, the reinforcing layer 12 serves as the wire reinforcing layer. When the reinforcing layer 12 includes two or more reinforcing layers within the reinforcing layer 12, it is sufficient that the outermost layer of the reinforcing layer 12 is a wire reinforcing layer. Furthermore, when the reinforcing layer 12 includes two or more reinforcing layers within the reinforcing layer 12, a reinforcing layer other than the outermost layer within the reinforcing layer 12 may be a wire reinforcing layer. The outer layer 13 is a cured product of the rubber composition of the present invention. The reinforcing layer 12 and the outer layer 13 can be bonded together, for example, by curing (crosslinking) the rubber composition of the present invention while the reinforcing layer 12 and the rubber composition of the present invention are adjacent to each other. The inner layer 11 may be a cured product of the rubber composition of the present invention or a cured product of a composition other than the rubber composition of the present invention. The reinforcing layer 12 and the inner layer 11 can be bonded together, for example, by curing (crosslinking or vulcanizing) the composition for the reinforcing layer 12 and the composition for the inner layer 11 while they are adjacent to each other.

[0057] Inner Layer The hose of the present invention has an inner layer. The thickness of the inner layer is not particularly limited, but can be, for example, 0.2 to 3 mm. The material applied to the inner layer (composition for inner layer) is not particularly limited, and examples thereof include rubber compositions or resin compositions that can be applied to the inner layer of hydraulic hoses and the like. The inner layer may be, for example, a cured product of a material (composition for inner layer) to be applied to the inner layer. The inner layer of the hose of the present invention is cylindrical.

[0058] [Reinforcement layer] The hose of the present invention has a reinforcing layer. The thickness of the reinforcing layer (the entire reinforcing layer) is not particularly limited, but can be, for example, 0.3 to 1 mm. The reinforcing layer in the hose of the present invention is cylindrical.

[0059] [Wire reinforcement layer] In the hose of the present invention, the reinforcing layer includes a brass-plated wire reinforcing layer. The wire reinforcing layer is a reinforcing layer formed of brass-plated wire. The brass-plated wire used in the wire reinforcing layer is not particularly limited as long as it is a metal wire that has been brass-plated. The wire reinforcement layer may be in the form of a spiral or braided structure, for example. The reinforcing layer may include at least one wire reinforcing layer, and may include 2 to 10 wire reinforcing layers.

[0060] [Wire reinforcement layer adjacent to outer layer] In the hose of the present invention, the wire-reinforced layer is adjacent to the outer layer. When the reinforcing layer is composed of one layer, the one reinforcing layer is a wire reinforcing layer. When the reinforcing layer includes two or more reinforcing layers within one reinforcing layer, the outermost layer within the reinforcing layer may be the wire reinforcing layer. Furthermore, when the reinforcing layer includes two or more reinforcing layers within one reinforcing layer, a reinforcing layer other than the outermost layer within the reinforcing layer may be the wire reinforcing layer. When the reinforcing layer includes two or more reinforcing layers within one reinforcing layer, and a reinforcing layer other than the outermost layer within the reinforcing layer is a reinforcing layer other than the wire reinforcing layer (another reinforcing layer), there are no particular limitations on the reinforcing layer other than the wire reinforcing layer (another reinforcing layer). Examples of the reinforcing layer other than the wire reinforcing layer (another reinforcing layer) include an unplated wire reinforcing layer and a wire reinforcing layer plated with a material other than brass plating.

[0061] [Outer layer] The hose of the present invention has an outer layer, which is a cured product of the rubber composition for a hose of the present invention. The thickness of the outer layer is not particularly limited, but can be, for example, 0.2 to 3 mm. The material applied to the outer layer (outer layer composition) is not particularly limited as long as it is the rubber composition for a hose of the present invention. The outer layer of the hose of the present invention is cylindrical.

[0062] (Hose manufacturing method) Examples of methods for producing a hose of the present invention include a method for producing a hose of the present invention by crosslinking, by primary crosslinking only, an uncrosslinked hose having an inner layer composition, a reinforcing layer, and an outer layer composition in this order, the reinforcing layer including a brass-plated wire reinforcing layer that is adjacent to the outer layer composition (that is, when the reinforcing layer is composed of a single layer, the wire reinforcing layer is disposed as the single reinforcing layer. When a single reinforcing layer includes two or more reinforcing layers, the wire reinforcing layer is disposed as the outermost layer within the reinforcing layer), and the outer layer composition is the rubber composition for a hose of the present invention. In the above-mentioned manufacturing method, the rubber composition for a hose of the present invention as the inner layer composition, reinforcing layer, and outer layer composition used in the uncrosslinked hose are the same as those described above.

[0063] Specifically, for example, first, an inner layer composition, a reinforcing layer, and an outer layer composition are arranged in this order on a mandrel. When the reinforcing layer is composed of a single layer, a wire reinforcing layer is arranged as the single reinforcing layer. When a single reinforcing layer includes two or more reinforcing layers, a wire reinforcing layer is arranged as the outermost layer within the reinforcing layer. A wire reinforcing layer may be arranged as a layer other than the outermost layer within the reinforcing layer. In this manner, an uncrosslinked hose is prepared. Next, the uncrosslinked hose is crosslinked by primary crosslinking only.

[0064] (Primary crosslinking) In the above-mentioned production method, the rubber composition of the present invention is used as the outer layer composition, so that the hose of the present invention can be produced by only primary crosslinking. The conditions for producing the hose of the present invention by crosslinking the rubber composition of the present invention only by primary crosslinking include a crosslinking temperature of, for example, 150 to 180°C and a crosslinking time of, for example, 60 to 240 minutes. When the rubber composition of the present invention is crosslinked by primary crosslinking under the above conditions, there is no need to carry out secondary crosslinking, which is usually required when crosslinking a rubber composition containing an acrylic rubber. The hose of the present invention can be manufactured by the above manufacturing method.

[0065] The hose of the present invention can be used, for example, as a hose for low pressure or hydraulic pressure. The inner diameter of the hose of the present invention can be, for example, 5 to 60 mm. The length of the hose of the present invention can usually be set to 0.1 to 200 m. [Example]

[0066] The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0067] [Production of rubber composition] Each rubber composition was produced by mixing the components shown in Table 1 in the composition (parts by mass) shown in the table with a mixer. The content of the triazine compound in Table 1 is the amount of a commercially available product (trade name: ZISNET F-OT) used as the triazine compound.

[0068] [evaluation] The rubber compositions produced as described above were subjected to the following evaluations, and the results are shown in Table 1.

[0069] [Wire adhesion] (Hose sample production) First, a single wire-reinforced layer was formed by winding brass-plated wire in a braid shape around a mandrel with an outer diameter of 34 mm. Next, a 1.2 mm-thick unvulcanized sheet prepared from each of the rubber compositions produced as described above was laminated onto the wire-reinforced layer. Furthermore, a nylon 66 curing tape (protective cloth) was wrapped around the outside of the unvulcanized sheet, and crosslinking was performed using a steam crosslinking method (160°C, 90 minutes) (primary crosslinking). In this way, a hose sample comprising a wire-reinforced layer and an outer layer was produced. In producing the hose sample, secondary crosslinking was not performed after the primary crosslinking.

[0070] (Evaluation of wire adhesion) The adhesive strength (kN / m) of each of the hose samples obtained as described above was evaluated. In the present invention, adhesive strength (kN / m) refers to the magnitude of force (kN) per unit width (m) required to peel the outer layer from the wire-reinforced layer (at a peel rate of 50 mm / min). The adhesive strength (kN / m) values ​​shown in Table 1 are the average values ​​of the results of two runs of the above-mentioned peel test (average adhesive strengths measured using two hose samples). The average adhesive strength values ​​obtained as described above are shown in the wire adhesion column of Table 1.

[0071] (Evaluation criteria for wire adhesion) In the present invention, when the adhesive strength (average value; the same applies hereinafter) was 1.8 kN / m or more, the wire adhesiveness was evaluated as excellent. The greater the adhesive strength is than 1.8 kN / m, the better the wire adhesiveness is. On the other hand, when the adhesive strength was less than 1.8 kN / m, the wire adhesiveness was evaluated as poor.

[0072] [Tensile strength, elongation at break] (Preparation of test specimens) Each rubber composition produced as described above was crosslinked for 90 minutes (primary crosslinking) using a press molding machine at 160°C under a surface pressure of 3.0 MPa to produce a crosslinked sheet having a thickness of 2 mm. A JIS No. 3 dumbbell-shaped test piece conforming to JIS K6251 was punched out from each crosslinked sheet to produce a test piece. In producing the test piece, secondary crosslinking was not performed after the primary crosslinking.

[0073] (Tensile test) Using each of the above test pieces, a tensile test was performed in accordance with JIS K6251:2017 at 23°C and a tensile speed of 500 mm / min to measure the tensile strength at break (Tb) [MPa] and elongation at break (Eb) [%]. The results of the tensile strength at break (Tb) are shown in the tensile strength (Tb) column of Table 1. The results of the elongation at break (Eb) are shown in the elongation (Eb) column of Table 1.

[0074] (Evaluation criteria for tensile strength) In the present invention, when the tensile strength at break was 9.5 MPa or more, the resulting cured product was evaluated as having excellent tensile strength. The greater the tensile strength at break was 9.5 MPa, the more excellent the tensile strength of the resulting cured product was evaluated as. On the other hand, if the tensile strength at break was less than 9.5 MPa, the tensile strength of the resulting cured product was evaluated as poor.

[0075] (elongation evaluation criteria) In the present invention, the elongation at break is preferably 170% or more. When the elongation at break is 170% or more, it is believed that the hose has excellent durability due to improved flexibility.

[0076] [hardness] (Preparation of test specimens) Each rubber composition prepared as described above was crosslinked for 90 minutes using a press molding machine at 160°C under a surface pressure of 3.0 MPa (primary crosslinking) to prepare a Lübke sample (a cylindrical shape with a thickness of 12.5 mm and a diameter of 29 mm). In preparing the Lübke sample, secondary crosslinking was not performed after the primary crosslinking. (Hardness measurement) Using each of the Lupke samples prepared as described above, the rubber hardness was measured at a temperature of 23°C using a durometer type A in accordance with JIS K6253-3:2012.

[0077] (Hardness evaluation criteria) In the present invention, the hardness is preferably 65 to 85. When the hardness is within the above range, it is believed that excellent crimping sealing properties can be achieved when the hose is joined to the metal pipe.

[0078] [Table 1]

[0079] Details of each component shown in Table 1 are as follows: (acrylic rubber) Acrylic rubber 1: Acrylic rubber containing ethylene monomer units, vinyl acetate monomer units, acrylic ester monomer units, and carboxyl group monomer units. Product name: Denka ER A804, manufactured by Denka Co., Ltd.

[0080] (carbon black) FEF carbon black: Asahi #60, manufactured by Asahi Carbon Co., Ltd. N2SA40-45m 2 / g, DBP oil absorption 121ml / 100g, iodine adsorption 42mg / g.

[0081] Antioxidant: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (secondary amine). Product name: Naugard #445, manufactured by SI Group Japan. Stearic acid: Stearic acid 50S, manufactured by New Japan Chemical Co., Ltd. Primary monoamine: N-octadecylamine. Product name: Lipomin 18D, manufactured by Lion Corporation. Plasticizer 1: Adipic acid bis[2-(2-butoxyethoxy)ethyl ester]. Trade name: TP-95, manufactured by The HallStar Company. Molecular weight: 434.56 Triazine-based compound: A mixture of 2,4,6-trimercapto-1,3,5-triazine (2,4,6-trimercapto-s-triazine) and oil. Product name: ZISNET F-OT, manufactured by Sankyo Kasei Co., Ltd. The net 2,4,6-trimercapto-1,3,5-triazine content of the above commercially available product is 85% by mass.

[0082] (Ethylene-glycidyl (meth)acrylate copolymer) Ethylene-glycidyl (meth)acrylate copolymer: Ethylene-glycidyl methacrylate-methyl acrylate copolymer. Product name: Bondfast BF-7L, manufactured by Sumitomo Chemical Co., Ltd. Glycidyl methacrylate (GMA) 3% by mass, methyl acrylate (MA) 27% by mass, ethylene 50-70% by mass

[0083] Epoxy resin (for comparison): Compound name: A mixture of 2,2-bis(4-hydroxyphenyl)propane diglycidyl ether modified with epichlorohydrin and butyl glycidyl ether. Product name: Epotohto YD-115, manufactured by Nippon Steel Chemical & Material Co., Ltd. The above epoxy resin (comparison) does not contain an ethylene-glycidyl (meth)acrylate copolymer.

[0084] (Diamine crosslinker) Diamine crosslinker: 2,2-bis[4-(4-aminophenoxy)phenyl]propane. Product name: KA-4, manufactured by Wakayama Seika Co., Ltd.

[0085] Crosslinking accelerator: A synthetic mixture of an active amine and a retarder. Trade name: XLA-60, manufactured by LANXESS. XLA-60 contains 1,8-diazabicyclo[5.4.0]undec-7-ene (structure shown below) as the active amine. [ka]

[0086] From the results in Table 1, Comparative Example 1, which did not contain an ethylene-glycidyl (meth)acrylate copolymer or a triazine compound, had poor wire adhesiveness and tensile strength. In Comparative Examples 2 and 3, in which a triazine-based compound was added to Comparative Example 1, the tensile strength was lower than that of Comparative Example 1. Comparative Example 4, which did not contain an ethylene-glycidyl (meth)acrylate copolymer but contained an epoxy resin (for comparison) instead, had poor wire adhesion and tensile strength.

[0087] On the other hand, it was confirmed that the rubber composition of the present invention exhibited the desired effects. By containing the ethylene-glycidyl (meth)acrylate copolymer, the rubber composition of the present invention had improved wire adhesion and tensile strength compared to Comparative Example 1. From the comparison results of Examples 2 and 3, it was surprisingly found that when the rubber composition of the present invention further contains a triazine-based compound, the excellent tensile strength obtained when the rubber composition of the present invention does not contain a triazine-based compound can be maintained, while the wire adhesion can be further improved compared to when the rubber composition of the present invention does not contain a triazine-based compound. From the comparison results between Comparative Example 4 and Example 1, Example 1 containing an ethylene-glycidyl (meth)acrylate copolymer had better wire adhesion and tensile strength than Comparative Example 4 containing the above-mentioned epoxy resin (comparison). Furthermore, the rubber composition of the present invention provides a cured product with excellent elongation at break, and the hardness of the cured product can be adjusted to an appropriate range.

[0088] (Evaluation of primary crosslinking by wire adhesion and tensile strength) In the present invention, when the wire adhesion of the hose sample and the tensile strength of the test piece obtained by carrying out only the primary crosslinking as described above both satisfy the above evaluation criteria, it was considered that the rubber composition of the present invention was able to be sufficiently crosslinked (cured) by crosslinking only by the primary crosslinking. In Examples 1 to 3, both the wire adhesion and the tensile strength of the test pieces satisfied the above evaluation criteria, so it can be said that the rubber composition of the present invention was able to be sufficiently crosslinked (cured) by primary crosslinking alone. On the other hand, Comparative Examples 1 to 4 were poor in at least tensile strength, and therefore the rubber compositions of Comparative Examples 1 to 4 could not be sufficiently crosslinked (cured) by primary crosslinking alone. [Explanation of symbols]

[0089] 1 hose 11 Inner layer 12 Reinforcement layer 13 Outer layer

Claims

1. a rubber component containing an acrylic rubber having ethylene monomer units, vinyl acetate monomer units, acrylic acid ester monomer units, and carboxy group monomer units; Carbon black and a diamine crosslinker; and an ethylene-glycidyl (meth)acrylate copolymer.

2. 2. The rubber composition for a hose according to claim 1, wherein the content of the ethylene-glycidyl (meth)acrylate copolymer is 18 to 22 parts by mass per 100 parts by mass of the rubber component.

3. 2. The rubber composition for a hose according to claim 1, further comprising a triazine-based compound, the content of the triazine-based compound being 0.2 to 1 part by mass per 100 parts by mass of the rubber component.

4. The rubber composition for a hose according to claim 1, further comprising an ether-based plasticizer.

5. The rubber composition for a hose according to claim 4, wherein the ether-based plasticizer comprises dibutyl carbitol adipate.

6. A hose having an inner layer, a reinforcing layer, and an outer layer in this order, wherein the reinforcing layer includes a brass-plated wire reinforcing layer, the wire reinforcing layer is adjacent to the outer layer, and the outer layer is a cured product of the rubber composition for a hose according to any one of claims 1 to 5.

7. A method for producing a hose according to claim 6, wherein an uncrosslinked hose having an inner layer composition, a reinforcing layer, and an outer layer composition in this order, the reinforcing layer including a brass-plated wire reinforcing layer, the wire reinforcing layer being adjacent to the outer layer composition, and the outer layer composition being the rubber composition for a hose according to any one of claims 1 to 5, is crosslinked only by primary crosslinking to produce the hose according to claim 6.

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