Rubber composition for rubber layer of laminate hose, laminate hose, and laminate hose for automobile

Abstract

To provide a laminate hose having excellent interlayer adhesion and excellent sealability.SOLUTION: A rubber composition for an inside rubber layer 1 and / or an outside rubber layer 3, contains the following components (A) to (D): (A) an ethylene-propylene-diene terpolymer; (B) a tackifier containing structural units derived from an aromatic monomer; (C) a bismaleimide compound; (D) a vulcanizing agent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a multilayer hose including a laminate structure with a rubber layer, and specifically to an engine cooling system hose such as a radiator hose used to connect the engine and radiator in an automobile or the like, a heater hose used to connect the engine and heater core, a hose for transporting refrigerant for a cooler, a hose for fuel cell vehicles such as a methanol fuel hose, a hydrogen fuel hose, and an automotive laminated hose such as a gasoline fuel hose, which relates to a multilayer hose including a laminate structure formed by laminating a rubber layer and a resin layer such as a reinforcing layer. [Background technology]

[0002] Conventionally, laminated hoses used in vehicles such as automobiles, for example, engine cooling system hoses such as radiator hoses used to connect an engine and a radiator, and heater hoses used to connect an engine and a heater core, have been hoses with a three-layer structure (inner rubber layer / reinforcing thread layer / outer rubber layer) in which a reinforcing thread layer or the like is formed on the outer peripheral surface of an inner rubber layer, and an outer rubber layer is further formed on the outer peripheral surface of that reinforcing thread layer. A hose having such a structure is manufactured, for example, by extruding a material for the inner rubber layer to form an inner rubber layer, applying an adhesive to the outer peripheral surface of the inner rubber layer, braiding reinforcing threads such as nylon threads (polyamide threads) or aramid threads on the outer peripheral surface to form a reinforcing thread layer, extruding a material for the outer rubber layer on the outer peripheral surface of the reinforcing thread layer to form an outer rubber layer, and crosslinking them (see, for example, Patent Document 1, etc.), or by extruding a material for the inner rubber layer to form an inner rubber layer, braiding reinforcing threads such as nylon threads (polyamide threads) or aramid threads on the outer peripheral surface of the inner rubber layer to form a reinforcing thread layer, applying an adhesive to the outer peripheral surface of the reinforcing thread layer, extruding a material for the outer rubber layer to form the outer rubber layer, and crosslinking them. In some cases, dipped threads dipped in an adhesive are used as the reinforcing threads.

[0003] However, according to the investigations of the present inventors, when the adhesive coating process or dipping process as described above is carried out, it is difficult to ensure good uniform interlayer adhesion in a multi-layer hose due to uneven coating or uneven impregnation, and there is a problem in that the high level of sealing required for automobile hoses, etc. cannot be ensured. In addition, adhesives are usually made by dissolving the adhesive components in solvents that are classified as Class 4 hazardous materials, such as toluene, xylene, and methyl ethyl ketone, which generates volatile organic compounds (VOCs) during the manufacturing process, posing a problem of contributing to the deterioration of the global environment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2012 / 133385 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-layer hose which has excellent interlayer adhesion and sealing properties even without the use of adhesive. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems. In the course of their research, they have found that if the rubber composition constituting the rubber layer of a multi-layer hose contains (A) an ethylene-propylene-diene terpolymer, (B) a tackifier containing a structural unit derived from an aromatic monomer, (C) a bismaleimide compound, and (D) a vulcanizing agent, the interlayer adhesion between the rubber layer and the adherend layer is good, and as a result, a multi-layer hose with excellent sealing properties can be provided.

[0007] That is, in the course of research into a multi-layer hose with excellent interlayer adhesion, the present inventors considered compounding various tackifiers, but found that it was difficult to sufficiently improve the interlayer adhesion by simply compounding various tackifiers in the rubber composition for the rubber layer. As a result of further research focusing on the affinity between the rubber component and other compounding components and the interactions between the respective compounding components, as well as the study of tackifiers, the present inventors found that the interlayer adhesion in a multi-layer hose can be improved by using an ethylene-propylene-diene terpolymer among various rubbers and using a specific tackifier and a bismaleimide compound in combination among various compounding agents, and arrived at the present invention.

[0008] That is, the gist of the present invention is the following [1] to

[12] . [1] A rubber composition for a rubber layer of a multilayer hose, comprising the following components (A) to (D): (A) Ethylene-propylene-diene terpolymer. (B) A tackifier containing a structural unit derived from an aromatic monomer. (C) Bismaleimide compounds. (D) Vulcanizing agent. [2] The rubber composition for a rubber layer according to [1], wherein the component (B) is a tackifier containing 20 mass % or more of a structural unit derived from an aromatic monomer. [3] The rubber composition for a rubber layer according to [1] or [2], wherein the total content (B+C) of the components (B) and (C) is 2.5 to 20 parts by mass per 100 parts by mass of the component (A). [4] The rubber composition for a rubber layer according to any one of [1] to [3], wherein a mass ratio (B / C) of the component (B) to the component (C) is 0.25 to 1.5. [5] The rubber composition for a rubber layer according to any one of [1] to [4], wherein the component (C) is an aromatic bismaleimide compound. [6] The rubber composition for a rubber layer according to any one of [1] to [5], wherein the component (B) is a tackifier further comprising a structural unit derived from an aliphatic monomer. [7] The rubber composition for the rubber layer according to any one of [1] to [6], wherein the multi-layer hose is a multi-layer hose having a multi-layer structure formed by laminating a rubber layer and a resin layer. [8] The rubber composition for a rubber layer according to [7], wherein the resin layer is a reinforcing thread layer made of reinforcing threads including at least one selected from the group consisting of polyamide threads, polyethylene terephthalate threads, and polyvinyl alcohol threads. [9] A multilayer hose comprising a laminate structure formed by laminating a rubber layer made of a vulcanizate of the rubber composition for rubber layer according to any one of [1] to [6] and a resin layer.

[10] The laminated hose according to [9], wherein the resin layer is a reinforcing fiber layer.

[11] A laminated hose for automobiles, comprising a laminated structure obtained by laminating in this order: a first rubber layer made of a vulcanizate of the rubber composition for rubber layer according to any one of [1] to [6]; a reinforcing fiber layer; and a second rubber layer made of a vulcanizate of the rubber composition for rubber layer containing the component (A) and the component (D). That is, the laminated hose for automobiles includes a laminated structure in which a first rubber layer made of a vulcanizate of a rubber composition for a rubber layer containing the following components (A) to (D) and a second rubber layer made of a vulcanizate of a rubber composition for a rubber layer containing the following components (A) and (D) are laminated in this order. (A) Ethylene-propylene-diene terpolymer. (B) A tackifier containing a structural unit derived from an aromatic monomer. (C) Bismaleimide compounds. (D) Vulcanizing agent.

[12] The laminated hose for automobiles according to

[11] , wherein the second rubber layer is a rubber layer made of a vulcanizate of a rubber composition for rubber layer further containing a (B) component and / or a (C) component. Effect of the Invention

[0009] According to the present invention, it is possible to provide a multi-layer hose that has excellent interlayer adhesion and sealing properties without using any particular adhesive.

[0010] In addition, according to one embodiment of the present invention, it is possible to reduce volatile organic compounds (VOCs), thereby contributing to the preservation of the global environment. Furthermore, according to one embodiment of the present invention, it is possible to eliminate an adhesive application process and the like in the manufacturing process of a multi-layer hose, which is extremely advantageous in terms of manufacturing costs. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an example of a hose of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the test method shown in this specification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, an embodiment of the present invention will be described in detail. In this specification, the term "main component" means a component that has a significant effect on the properties of the material, and the content of the component is 50% by mass or more of the entire material, unless otherwise specified, and is preferably 60 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, etc. In addition, in this specification, "X and / or Y (X and Y are optional configurations)" means at least one of X and Y, and means the following three cases: X only, Y only, and X and Y.

[0013] <<Rubber composition for rubber layer>> The rubber composition for a rubber layer of the present invention (hereinafter, may be referred to as "the rubber composition") is characterized by containing components (A) to (D). (A) Ethylene-propylene-diene terpolymer. (B) A tackifier containing a structural unit derived from an aromatic monomer. (C) Bismaleimide compounds. (D) Vulcanizing agent.

[0014] The reason why high interlayer adhesion is obtained in a laminated hose using the rubber composition containing all of the components (A) to (D), is not entirely clear, but it is presumed that the combined use of the tackifier (B) containing a structural unit derived from an aromatic monomer and the bismaleimide compound (C) reduces the affinity for the ethylene-propylene-diene terpolymer (A) and promotes migration to the rubber layer surface, thereby contributing to the formation of a diffusion layer, strengthening the integration between the layers, and increasing the interlayer adhesion.

[0015] Specifically, for example, in a laminated hose including a laminate structure formed by laminating a rubber layer using the present rubber composition and a reinforcing fiber layer, the (C) and (B) components are attracted to and mixed through their interaction, and migration to the interface is promoted. This, combined with migration of the (D) component to the interface, promotes impregnation of the reinforcing fiber layer, and as a result, they form a strong crosslinked structure, strengthening the integration between the layers and increasing the interlayer adhesive strength.

[0016] By using this rubber composition, it is possible to provide a multi-layer hose with high interlayer adhesion and excellent sealing properties without using any adhesive, which can contribute to the preservation of the global environment by reducing, for example, volatile organic compounds (VOCs). Furthermore, it is possible to eliminate the adhesive application step and dipping treatment step in the manufacturing process of the multi-layer hose, thereby reducing manufacturing costs.

[0017] In the course of research, the present inventors have also found that the use of this rubber composition makes it possible to achieve a high level of both interlayer adhesion and compression set in a multilayer hose. That is, in the course of research into improving the interlayer adhesion in a multilayer hose, they have considered achieving a high level of both interlayer adhesion and compression set, which is one of the important properties of a multilayer hose, but it has been difficult to sufficiently improve both interlayer adhesion and compression set. As a result of further research focusing on the affinity between the rubber component and other compounding components and the interactions between each compounding component, as well as the study of tackifiers, the present inventors have also found that the use of this rubber composition makes it possible to achieve a high level of both interlayer adhesion and compression set in a multilayer hose. This rubber composition is very useful in that it can achieve both interlayer adhesion and compression set. Hereinafter, the embodiments of the present invention will be described in more detail.

[0018] [(A) Ethylene-propylene-diene terpolymer (EPDM)] The component (A) used in this rubber composition is an ethylene propylene rubber (EPM), a copolymer of ethylene and propylene, copolymerized with a diene monomer as a third component (hereinafter sometimes abbreviated as "EPDM"). The component (A) may be used alone or in combination of two or more kinds.

[0019] The diene monomer (third component) contained in the component (A) is not particularly limited, but is preferably a diene monomer having 5 to 20 carbon atoms. Specific examples include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene, 1,4-octadiene, 1,4-cyclohexadiene, cyclooctadiene, dicyclopentadiene (DCP), 5-ethylidene-2-norbornene (ENB), 5-butylidene-2-norbornene, and the like. These are used alone or in combination of two or more. Among these, dicyclopentadiene (DCP) and 5-ethylidene-2-norbornene (ENB) are preferred.

[0020] The ethylene content of the component (A) is not particularly limited, but from the viewpoint of achieving a remarkable effect of the present invention, it is preferably from 48 to 70 mass %, and more preferably from 50 to 60 mass %. Furthermore, the propylene content of the component (A) is not particularly limited, but from the viewpoint of achieving a remarkable effect of the present invention, it is preferably from 22 to 46 mass %, and more preferably from 30 to 44 mass %. Furthermore, the diene monomer content of the component (A) is not particularly limited, but is preferably from 3 to 11 mass %, and more preferably from 3.5 to 6 mass %. The iodine value of the component (A) is not particularly limited, but is preferably from 6 to 30, and more preferably from 10 to 24, from the standpoint of achieving the effects of the present invention prominently.

[0021] The content of component (A) is not particularly limited, but is usually 20% by mass or more, preferably 25% by mass or more, and more preferably 28 to 60% by mass, based on the rubber composition (100% by mass).

[0022] [(B) Tackifier] In the present rubber composition, it is particularly important to use a tackifier containing a structural unit derived from an aromatic monomer among various tackifiers. That is, the (B) component may be, for example, an addition polymer of an aromatic monomer having an ethylenic carbon-carbon double bond, such as indene, vinyltoluene, styrene, α-methylstyrene, isopropenyl, etc. The (B) component may be a homopolymer of the above monomer, a copolymer of two or more monomers in which the above monomers are appropriately combined, or a copolymer of a component other than the aromatic monomer, such as an aliphatic monomer, such as isoprene, 1,3-pentadiene, or 2-methyl-2-butene. Furthermore, the component (B) may be modified with a phenol compound, maleic anhydride, acrylic acid, methacrylic acid, etc. The component (B) may be used alone or in combination of two or more kinds.

[0023] Among the (B) components, from the viewpoint of significantly achieving the effects of the present invention, a hydrocarbon-based tackifier resin containing a structural unit derived from an aromatic monomer is preferred. Examples of the hydrocarbon-based tackifier resin include aromatic (C9) petroleum resins, aliphatic / aromatic copolymer (C5 / C9) petroleum resins, hydrogenated products thereof, various modified products thereof (e.g., maleic anhydride modified products), and coumarone resins.

[0024] The aromatic (C9) petroleum resin is not particularly limited, but is preferably an aromatic (C9) petroleum resin composed of one or more structural units selected from the group consisting of indene, styrene, and vinyltoluene, and more preferably an aromatic (C9) petroleum resin composed of two or three structural units selected from the group consisting of indene, styrene, and vinyltoluene. The aliphatic / aromatic copolymer (C5 / C9) petroleum resin is not particularly limited, but is preferably an aliphatic / aromatic copolymer (C5 / C9) petroleum resin composed of one or more structural units selected from the group consisting of indene, styrene, and vinyltoluene, and isoprene and / or piperylene. The coumarone resin is not particularly limited, but is preferably a coumarone resin containing a structural unit derived from coumarone and further composed of one or more structural units selected from the group consisting of indene, styrene, and vinyltoluene.

[0025] Examples of the component (B) include alkylphenol resins, terpene phenol resins, rosin phenol resins, and styrene resins.

[0026] The alkylphenol resin is not particularly limited as long as it is used as a tackifier, and is a resin obtained from an alkylphenol and formaldehyde. Examples of the alkylphenol resin include condensation polymers of various alkylphenols such as o-cresol, m-cresol, p-cresol, ethylphenol, iso-propylphenol, xylenol, 3,5-xylenol, butylphenol, pt-butylphenol, and nonylphenol with formaldehyde. The terpene phenolic resin is not particularly limited as long as it is used as a tackifier, and examples thereof include both copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins) and phenol-modified homopolymers or copolymers of terpenes (phenol-modified terpene resins). Examples of the terpenes that constitute the terpene phenolic resins include monoterpenes such as α-pinene, β-pinene, and limonene (including d-, l-, and d / l-forms (dipentene)). The rosin phenolic resin is not particularly limited as long as it is usable as a tackifier, and examples thereof include those obtained by addition reaction of natural rosin, rosin derivatives, etc. with phenols, and so-called rosin-modified phenolic resins obtained by reacting a resol-type phenolic resin with a rosin-based resin, etc. The rosin phenolic resin may be used as a metal salt of the rosin phenolic resin, or may be an ester obtained by reacting a rosin-based resin with a polyhydric alcohol. The styrene resin is not particularly limited as long as it is usable as a tackifier, and examples thereof include those mainly composed of a homopolymer of styrene, those mainly composed of a homopolymer of α-methylstyrene, those mainly composed of a homopolymer of vinyltoluene, and those mainly composed of a copolymer containing two or more of styrene, α-methylstyrene, and vinyltoluene in the monomer composition.

[0027] From the viewpoint of further improving interlayer adhesion, the (B) component is preferably a tackifier in which the content of structural units derived from aromatic monomers is 20% by mass or more relative to the total structural units of the (B) component. From the same viewpoint, the content of structural units derived from aromatic monomers is more preferably 35% by mass or more, even more preferably 40% by mass or more, particularly preferably 50% by mass or more, and especially preferably 60 to 100% by mass.

[0028] When component (B) contains structural units other than structural units derived from aromatic monomers (for example, structural units derived from aliphatic monomers), the content thereof is preferably 80 mass% or less, more preferably 65 mass% or less, even more preferably 55 mass% or less, particularly preferably 45 mass% or less, and especially preferably 40 mass% or less, based on the total structural units of component (B).

[0029] The softening point of the component (B) is not particularly limited, but is, for example, preferably from 50 to 200° C., more preferably from 60 to 150° C., and even more preferably from 70 to 120° C. The softening point is measured by the ring and ball method in accordance with JIS K2207.

[0030] The content of the (B) component is not particularly limited, but from the viewpoint of prominently exhibiting the effects of the present invention, it is preferably 1.25 to 10 parts by mass, more preferably 2.5 to 8 parts by mass, and even more preferably 3 to 7 parts by mass, per 100 parts by mass of the (A) component.

[0031] [(C) Bismaleimide compound] The component (C) used in the rubber composition is a compound having two maleimide groups in the molecule, and examples of such compounds include aromatic bismaleimide compounds, aliphatic bismaleimide compounds, etc. These compounds may be used alone or in combination of two or more.

[0032] The aromatic bismaleimide compound is a compound containing a bismaleimide structure and a structure having an aromatic ring. Examples of the structure having an aromatic ring include an aryl group or an arylene group having 6 to 30 carbon atoms. The aryl group or the arylene group may have a substituent. Examples of the structure having an aromatic ring include a phenylene group, a methylphenylene group, an ethylphenylene group, a propylphenylene group, a butylphenylene group, a dimethylphenylene group, a diethylphenylene group, a dipropylphenylene group, a trimethylphenylene group, a tetramethylphenylene group, a dibutylphenylene group, a naphthylene group, a biphenylene group, a fluorenylene group, a phenanthrenylene group, and an anthraquinolylene group. Among these, the phenylene group is preferred.

[0033] Specific examples of aromatic bismaleimide compounds include N,N'-(1,3-phenylene)bismaleimide, N,N'-(4-methyl-1,3-phenylene)bismaleimide, N,N'-(1,4-phenylene)bismaleimide, N,N'-(1,2-phenylene)bismaleimide, N,N'-(1,5-naphthylene)bismaleimide, N,N'-(4-chloro-1,3-phenylene)bismaleimide, N,N'-(methylenedi-p-phenylene)bismaleimide, N,N'-(4,4'-biphenylene)bismaleimide, N,N'-(sulfonyldi-p-phenylene)bismaleimide, N,N'-(oxydi-p-phenylene)bismaleimide, N,N'-(3,3'-dimethyl-4,4'-biphenylene)bismaleimide, N,N'-(benzylidene di-p-phenylene)bismaleimide, N,N'-[methylenebis(3-chloro-4-phenylene)]bismaleimide, N,N'-[methylene bismaleimide, N,N'-[methylenebis(3-methyl-4-phenylene)]bismaleimide, N,N'-(thiodi-p-phenylene)bismaleimide, N,N'-3,3'-benzophenone bismaleimide, N,N'-[methylenebis(3-methyl-5-ethyl-4-phenylene)]bismaleimide, N,N'-[tetramethylenebis(oxy-p-phenylene)]bismaleimide, 2,2-bis[ Examples of such maleimide include 4-(4-maleimidophenoxy)phenyl]propane, bis[4-(4-maleimidophenoxy)phenyl]sulfone, 1,4-phenylenebis(4-maleimidophenoxy), bis[3-(4-maleimidophenoxy)phenyl]sulfone, bis[4-(3-maleimidophenoxy)phenyl]ketone, 1,3-phenylenebis(4-maleimidophenoxy), bis[4-(4-maleimidophenylthio)phenyl]ether, etc. Among these, N,N'-(1,3-phenylene)bismaleimide is preferred.

[0034] Examples of the aliphatic bismaleimide compound include N,N'-(2,2,4-trimethylhexamethylene)bismaleimide, N,N'-decamethylene bismaleimide, N,N'-octamethylene bismaleimide, N,N'-heptamethylene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-pentamethylene bismaleimide, N,N'-tetramethylene bismaleimide, N,N'-trimethylene bismaleimide, N,N'-ethylene bismaleimide, N,N'-(oxydimethylene)bismaleimide, 1,13-bismaleimide-4,7,10-trioxatridecane, and 1,11-bismaleimide-3,6,9-trioxaundecane.

[0035] Among these (C) components, aromatic bismaleimide compounds are preferred from the viewpoint of achieving the effects of the present invention more significantly. It is presumed that the use of an aromatic bismaleimide compound as the (C) component reduces the affinity for the (A) component and further promotes migration to the interface, resulting in higher interlayer adhesion.

[0036] The content of the (C) component is not particularly limited, but from the viewpoint of prominently exhibiting the effects of the present invention, it is preferably 1.25 to 10 parts by mass, more preferably 2.5 to 8 parts by mass, and even more preferably 4 to 7 parts by mass, per 100 parts by mass of the (A) component.

[0037] The mass ratio (B / C) of the (B) component to the (C) component is not particularly limited, but from the viewpoint of achieving both interlayer adhesion and compression set resistance, it is preferably 0.25 to 1.5. If it is outside the above range, it tends to be difficult to achieve both interlayer adhesion and compression set resistance. The mass ratio (B / C) can be appropriately set within the above range and is not particularly limited, but may be, for example, 0.4 to 1.3, 0.5 to 1.2, or 0.7 to 1.1, from the viewpoint of achieving both interlayer adhesion and compression set properties.

[0038] The total content (B+C) of the (C) component and the (B) component is not particularly limited, but from the viewpoint of achieving both interlayer adhesion and compression set, it is preferably 2.5 to 20 parts by mass, more preferably 4.5 to 14 parts by mass, and even more preferably 5 to 14 parts by mass, per 100 parts by mass of the (A) component. Outside the above range, it tends to be difficult to achieve both interlayer adhesion and compression set. The total content (B+C) can be appropriately set within the above range and is not particularly limited, but may be, for example, 6 to 12 parts by mass, from the viewpoint of achieving both interlayer adhesion and compression set properties.

[0039] [(D) Vulcanizing agent] Examples of component (D) include sulfur-based vulcanizing agents and peroxide-based vulcanizing agents, which may be used alone or in combination of two or more.

[0040] Examples of the sulfur-based vulcanizing agent include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur.

[0041] Examples of peroxide-based vulcanizing agents include 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, n-butyl-4,4'-di-t-butylperoxyvalerate, dicumyl peroxide, t-butylperoxybenzoate, di-t-butylperoxy-diisopropylbenzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3, and 1,3-bis-(t-butylperoxy-isopropyl)benzene.

[0042] When a sulfur-based vulcanizing agent is used as the component (D), the content of the sulfur-based vulcanizing agent is preferably 0.5 to 15 parts by mass, and particularly preferably 1 to 5 parts by mass, per 100 parts by mass of the component (A), in order to prominently exhibit the effects of the present invention.

[0043] When a peroxide-based vulcanizing agent is used as the component (D), the content of the peroxide-based vulcanizing agent is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 1.5 to 10 parts by mass, per 100 parts by mass of the component (A), from the viewpoint of significantly exhibiting the effects of the present invention.

[0044] [Other ingredients] In addition to the above components (A) to (D), the rubber composition may contain, without particular limitation, components used in rubber compositions, such as vulcanization accelerators, fillers, plasticizers, vulcanization aids, antioxidants, processing aids, and the like, as needed.

[0045] The vulcanization accelerator is not particularly limited, but examples thereof include thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), tetrakis(2-ethylhexyl)thiuram disulfide (TOT), and tetrabenzylthiuram disulfide (TBzTD); N-oxydiethylene-2-benzothiazolylsulfenamide (NOBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), Nt-butylthiuram disulfide (TBZTD), and the like. Examples of the vulcanization accelerators include sulfenamide-based vulcanization accelerators such as N,N'-dicyclohexyl-2-benzothiazoylsulfenamide (BBS) and N,N'-dicyclohexyl-2-benzothiazoylsulfenamide; thiazole-based vulcanization accelerators such as dibenzothiazyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazole sodium salt (NaMBT), and 2-mercaptobenzothiazole zinc salt (ZnMBT); dithioacid salt-based vulcanization accelerators such as zinc dibutyldithiocarbamate (ZnBDC); sulfur chloride, sulfur disulfide, etc. These may be used alone or in combination of two or more.

[0046] The content of the vulcanization accelerator is not particularly limited, but is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, per 100 parts by mass of the component (A).

[0047] The filler is not particularly limited, but examples thereof include carbon black, talc, mica, clay, calcium carbonate, etc. These may be used alone or in combination of two or more kinds. The carbon black is not particularly limited, but examples thereof include various grades of carbon black such as SAF grade, ISAF grade, HAF grade, MAF grade, FEF grade, GPF grade, SRF grade, FT grade, and MT grade. The content of the filler is not particularly limited, but is preferably 20 to 180 parts by mass, and more preferably 50 to 160 parts by mass, per 100 parts by mass of the component (A).

[0048] The plasticizer is not particularly limited, but examples thereof include aromatic oils, ether ester plasticizers, process oils, etc. These may be used alone or in combination of two or more kinds. Examples of aromatic oils include Diana Process AC-12, Diana Process AC-460, and Diana Process AH-16 (all manufactured by Idemitsu Showa Shell Co., Ltd.), JSO Aroma 790 (manufactured by Japan Sun Oil Co., Ltd.), Aromax 1, and Aromax 3 (all manufactured by Fuji Kosan Co., Ltd.). Examples of ether ester plasticizers include plasticizers having both ether bonds and ester bonds in one molecule, specifically, adipate ether ester plasticizers such as bis[2-(2-butoxyethoxy)ethyl] adipate. Examples of process oils include naphthenic oils and paraffinic oils. The content of the plasticizer is not particularly limited, but is preferably 5 to 100 parts by mass, and more preferably 20 to 80 parts by mass, per 100 parts by mass of the component (A).

[0049] The vulcanization aid is not particularly limited, but examples thereof include zinc oxide, zinc oxide (ZnO), stearic acid, magnesium oxide, etc. These may be used alone or in combination of two or more kinds. Examples of zinc oxide include zinc oxide type 1, zinc oxide type 2, zinc oxide type 3, and fine zinc oxide. The content of the vulcanization aid is not particularly limited, but is preferably 1 to 25 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of the component (A).

[0050] <<Laminated hose>> The present rubber composition is used as a material for a rubber layer constituting a multi-layer hose. The multi-layer hose has a laminate structure in which, for example, a rubber layer made of a vulcanizate of the present rubber composition and a resin layer to be adhered to the rubber layer are laminated. Examples of the resin constituting the main component of the resin layer include one or more selected from the group consisting of polyesters such as polyethylene terephthalate, polyvinyl alcohol, aramid (aromatic polyamide), polyamides such as polyamide 6 and polyamide 66, and the like.

[0051] The resin layer is not particularly limited as long as it has a specific function such as a reinforcing function or a permeation resistance function, but from the viewpoint of significantly achieving the effects of the present invention, it is preferable that it is a reinforcing layer, and it is more preferable that it is a reinforcing thread layer composed of resin reinforcing threads. Examples of the reinforcing yarns constituting the reinforcing yarn layer include polyester yarns such as polyethylene terephthalate yarns, polyvinyl alcohol yarns, aramid (aromatic polyamide) yarns, and polyamide yarns such as polyamide 6 and polyamide 66. These may be used alone or in combination of two or more. Among these, from the viewpoint of durability of the multilayer hose, at least one reinforcing yarn selected from the group consisting of polyamide yarns, polyethylene terephthalate yarns, and polyvinyl alcohol yarns is preferred. The reinforcing thread layer may be a reinforcing thread layer that has been dipped with an adhesive. The dipped reinforcing thread layer may be a layer formed by braiding reinforcing threads that have been dipped, or may be a reinforcing thread layer formed by braiding reinforcing threads that has been dipped. The method for braiding the reinforcing yarn is not particularly limited, and examples thereof include spiral braiding and braid braiding.

[0052] [Manufacturing method of multi-layer hose] An example of a method for producing a multi-layer hose using the present rubber composition will be described with reference to FIG. First, the rubber composition is prepared by blending the above components (A) to (D) and other components as required, and kneading them using a kneading machine such as a roll, a kneader, or a Banbury mixer. The rubber composition is then extruded into a hose shape, and then a reinforcing thread layer 2 is formed by, for example, winding a reinforcing thread in a spiral shape around the outer circumferential surface of the extrusion. Next, the rubber composition is extruded onto the outer circumferential surface of the reinforcing thread layer 2, and the resulting hose-shaped laminate is heated under predetermined conditions, whereby the reinforcing thread layer 2 is integrally formed with the outer circumferential surface of the inner rubber layer 1, and the outer rubber layer 3 is integrally formed with the outer circumferential surface of this reinforcing thread layer 2, thereby obtaining a laminated hose (see FIG. 1) having a three-layer structure (inner rubber layer 1 / reinforcing thread layer 2 / outer rubber layer 3).

[0053] In addition, since the interlayer adhesion between the rubber layers (inner rubber layer 1, outer rubber layer 3) made of this rubber composition and the reinforcing thread layer 2 is high, the above-mentioned lamination formation can be carried out without applying an adhesive (adhesive-free), but an adhesive may be used if necessary.

[0054] The dimensions of the multilayer hose thus obtained are not particularly limited, but the outer diameter of the multilayer hose is usually about 8 to 50 mm, and the total thickness (hose wall thickness) of the multilayer hose is usually about 1.8 to 6 mm. The thickness of each layer constituting the multilayer hose is also not particularly limited as long as it is within a range in which the intended function of each layer can be fully achieved, but for example, the thickness of the inner rubber layer 1 is usually about 1 to 4 mm, and the thickness of the outer rubber layer 3 is usually about 0.8 to 2 mm.

[0055] In the present invention, it is not necessary for both the inner rubber layer 1 and the outer rubber layer 3 to be constructed of rubber layers formed using a rubber composition containing the above-mentioned components (A) to (D). It is also possible for either the inner rubber layer 1 or the outer rubber layer 3 to be a general-purpose rubber layer formed using a general-purpose rubber material.

[0056] When a general-purpose rubber layer is formed from a composition other than the present rubber composition, the material is not particularly limited, and examples thereof include component (A), chloroprene rubber (CR), styrene butadiene rubber (SBR), acrylic rubber (ACM), ethylene acrylate rubber (AEM), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), etc. Also, acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile butadiene rubber (HNBR), acrylic rubber (ACM), ethylene acrylate rubber (AEM), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), fluororubber (FKM), etc. may be used. These may be used alone or in combination of two or more. Also, the rubber layer may be appropriately blended with additives such as fillers and plasticizers as necessary.

[0057] A preferred embodiment of the present invention is one in which one of the inner rubber layer 1 or the outer rubber layer 3 is a rubber layer formed using the rubber composition containing the above-mentioned components (A) to (D), and the other of the inner rubber layer 1 or the outer rubber layer 3 is a rubber layer formed using the rubber composition containing the above-mentioned components (A) and (D). A more preferred embodiment is one in which both the inner rubber layer 1 and the outer rubber layer 3 are rubber layers formed using the rubber composition containing the above-mentioned components (A) to (D).

[0058] Furthermore, the laminated hose according to the embodiment of the present invention is not limited to a three-layer structure (inner rubber layer 1 / reinforcing thread layer 2 / outer rubber layer 3) as shown in FIG. 1, but is not particularly limited as long as it has a two-layer or more structure having a laminated structure of a rubber layer made of the rubber composition and another layer (e.g., a reinforcing thread layer, etc.). Examples of such a hose include a laminated hose having a laminated structure of "resin layer (innermost layer) / rubber layer," in which the rubber layer is made of the present rubber composition, and a laminated hose having a four-layer structure of "resin layer (innermost layer) / inner rubber layer / reinforcing layer (e.g., a reinforcing layer made of metal wire) / outer rubber layer," in which the inner rubber layer and / or the outer rubber layer is made of the present rubber composition.

[0059] Preferable specific examples of the layer structure in the multilayer hose according to the embodiment of the present invention are not limited to the following, but specific examples include a multilayer hose having a three-layer structure of "inner rubber layer / reinforcing thread layer / outer rubber layer" in which the inner rubber layer and / or the outer rubber layer is a rubber layer made of the present rubber composition, and a multilayer hose having a four-layer structure of "inner rubber layer / middle rubber layer / reinforcing thread layer / outer rubber layer" in which the intermediate rubber layer and / or the outer rubber layer is a rubber layer made of the present rubber composition. Further, for example, in a multi-layer hose having a five-layer structure of "inner rubber layer / reinforcing thread layer / middle rubber layer / reinforcing thread layer / outer rubber layer," some (one or two) or all of the inner rubber layer, intermediate rubber layer, and outer rubber layer may be rubber layers made of the rubber composition.

[0060] The uses of the laminated hose according to the present invention are not particularly limited, and it can be suitably used as engine cooling system hoses such as a radiator hose used to connect the engine and radiator in vehicles such as automobiles, a heater hose used to connect the engine and heater core, a hose for transporting refrigerant for coolers, hoses for fuel cell vehicles such as a methanol fuel hose and a hydrogen fuel hose, and automobile hoses such as a gasoline fuel hose. EXAMPLES

[0061] Next, examples of the present invention will be described together with comparative examples, although the present invention is not limited to these examples.

[0062] Prior to the Examples and Comparative Examples, the following materials were prepared as components (A) to (D).

[0063] [EPDM (component A)] (A-1) Esprene (registered trademark) EPDM552 (iodine value: 12, ethylene ratio: 55% by mass), manufactured by Sumitomo Chemical Co., Ltd.

[0064] [Tackifier (Component B)] (B-1) Petrotack (registered trademark) 90HS (aromatic monomer ratio 20% by mass, petroleum resin), manufactured by Tosoh Corporation (B-2) Petrotack (registered trademark) 100V (aromatic monomer ratio 40 mass%, petroleum resin), manufactured by Tosoh Corporation (B-3) Petrotac (registered trademark) 90 (aromatic monomer ratio 70% by mass, petroleum resin), manufactured by Tosoh Corporation (B-4) Petcole (registered trademark) LX (aromatic monomer ratio 100% by mass, petroleum resin), manufactured by Tosoh Corporation (B-5) Nitto Chemical Co., Ltd., Knit Resin (registered trademark) Coumarone G-90 (aromatic monomer ratio 100% by mass, Coumarone resin)

[0065] [Tackifier (Component B')] (B'-1) Arakawa Chemical Industries, Ltd., Alcon (registered trademark) P-90 (aromatic monomer ratio 0 mass% (aliphatic monomer ratio 100 mass%), hydrogenated petroleum resin)

[0066] [Bismaleimide compound (component C)] (C-1) N,N'-(1,3-phenylene)bismaleimide, manufactured by Tokyo Chemical Industry Co., Ltd.

[0067] [Vulcanizing agent (Component D)] (D-1) SULFAX (registered trademark) PS (sulfur-based vulcanizing agent) manufactured by Tsurumi Chemical Industry Co., Ltd. (D-2) Percumyl (registered trademark) D (peroxide-based vulcanizing agent), manufactured by NOF Corporation

[0068] [Examples 1 to 10, Comparative Examples 1 to 8] First, the (A) to (D) components were mixed in the proportions shown in Table 1 below, and the optional components were 4 parts by mass of vulcanization accelerator, 155 parts by mass of filler, 5 parts by mass of zinc oxide, and 70 parts by mass of plasticizer (the above proportions are relative to 100 parts by mass of component (A)), to prepare a rubber composition for the rubber layer. Specifically, the components other than the component (D) and the vulcanization accelerator were added to the component (A) and mixed in a 1.7 L Banbury mixer, and then the component (D) and the vulcanization accelerator were added and mixed in an 8-inch roll to prepare a rubber composition for the rubber layer.

[0069] The vulcanization accelerators used were 1 part by mass each of tetramethylthiuram disulfide, tetraethylthiuram disulfide, N-cyclohexyl-2-benzothiazolylsulfenamide, and zinc dibutyldithiocarbamate (4 parts by mass in total). The fillers used were 120 parts by mass of SRF-grade carbon black, 15 parts by mass of talc, and 20 parts by mass of clay (155 parts by mass in total). The plasticizer used was paraffin-based process oil.

[0070] The rubber compositions for the rubber layer of the examples and comparative examples thus obtained were evaluated for properties according to the following criteria. The results are shown in Table 1 below.

[0071] [Interlayer adhesion test (thread / rubber pull-out test)] Unvulcanized rubber sheets (120mm x 120mm x 2mm) of the rubber composition for the rubber layer were prepared one by one (rubber sheet 11 and rubber sheet 13 in Fig. 2), and five reinforcing threads 12 (manufactured by Toray Industries, S-1400T / 1HH (polyamide thread [nylon 66])) with a total length of 300mm were arranged on one of the rubber sheets (rubber sheet 11) as shown in Fig. 2 (rubber contact part is about 30mm), and another rubber sheet (rubber sheet 13) was stacked on top of it, and vulcanization was performed by hot pressing at 150 °C x 30 minutes to prepare a test specimen. Then, the reinforcing threads 12 were pulled at 50mm / min, and the pull-out strength at that time was measured and evaluated according to the following criteria. (Evaluation Criteria) 〇...Pull-out strength is 40N or more per piece. ×...Pull-out strength is less than 40N / piece.

[0072] [Compression set test] According to JIS K 6262, the rubber composition for the rubber layer was vulcanized by holding it at 150°C for 30 minutes using a specified mold to prepare a circular test piece (large test piece) with a diameter of 29 mm and a thickness of 12.5 mm. According to JIS K 6262, the obtained test piece was left to stand at 125°C for 24 hours while compressed by 25%, and the compression set (%) was measured and evaluated according to the following criteria. (Evaluation Criteria) ◎...Compression set (%) is less than 65%. 〇...Compression set (%) is 65% or more and 70% or less. ×...Compression set (%) is over 70%.

[0073] [Table 1]

[0074] The results in the above table show that in the comparative example, a multi-layer hose using a rubber composition that does not contain any of the components (A) to (D) has insufficient adhesion between the rubber layer and the reinforcing fiber layer. Specifically, when the (B) and (C) components were not contained, as in Comparative Examples 1 and 2; when the (B) component was not contained, as in Comparative Examples 3 and 8; and when the (C) component was not contained, as in Comparative Examples 4 to 7, it was shown that the adhesion between the rubber layer and the reinforcing fiber layer was insufficient.

[0075] On the other hand, it was shown that a multi-layer hose using a rubber composition containing all of the components (A) to (D) as in the examples had excellent adhesion between the rubber layer and the reinforcing fiber layer.

[0076] In addition, the results in the above table show that in the comparative example, a multi-layer hose using a rubber composition that does not contain any of the components (A) to (D) cannot achieve both interlayer adhesion and compression set properties. On the other hand, it was shown that a multi-layer hose using a rubber composition containing all of the components (A) to (D) as in the examples can achieve both good interlayer adhesion and good compression set properties.

[0077] Furthermore, to verify the effect of the ratio of aromatic monomers in component (B) (the ratio of structural units derived from aromatic monomers) on interlayer adhesion, cases in which conditions other than the ratio of aromatic monomers in component (B) were the same were compared. Specifically, Examples 1 to 4 (ratios of 20 mass%, 40 mass%, 70 mass%, and 100 mass%) were compared with Comparative Example 3 (ratio of 0 mass%). As a result, when the result (N / piece) of [Interlayer adhesion test (yarn / rubber pull-out test)] in Comparative Example 3 was used as the standard and indexed to 100, Example 1 was 150, and Examples 2 to 4 were 175 or more. Therefore, it was shown that from the viewpoint of improving interlayer adhesion, the ratio of aromatic monomer in component (B) (the ratio of constituent units derived from aromatic monomer) is preferably 20 mass % or more, and particularly preferably 40 mass % or more. [Industrial Applicability]

[0078] The rubber composition for rubber layer of the present invention is suitable as, for example, a rubber layer of an automobile hose, and can be suitably used as, for example, an automobile hose such as a radiator hose used to connect an engine and a radiator in a vehicle such as an automobile, an engine cooling system hose such as a heater hose used to connect an engine and a heater core, a refrigerant transport hose for a cooler, a hose for fuel cell vehicles such as a methanol fuel hose and a hydrogen fuel hose, a gasoline fuel hose, etc. The automobile hose of the present invention can be used not only for automobiles, but also for other transport machines (airplanes, industrial transport vehicles such as forklifts, excavators and cranes, railway cars, etc.). [Explanation of symbols]

[0079] 1 Inner rubber layer 2 Reinforcing yarn layer 3 Outer rubber layer

Claims

1. A rubber composition for a rubber layer of a multilayer hose, comprising the following components (A) to (D): (A) Ethylene-propylene-diene terpolymer. (B) A tackifier containing a structural unit derived from an aromatic monomer. (C) Bismaleimide compounds. (D) a vulcanizing agent.

2. 2. The rubber composition for the rubber layer according to claim 1, wherein the component (B) is a tackifier containing 20% ​​by mass or more of structural units derived from an aromatic monomer.

3. 3. The rubber composition for the rubber layer according to claim 1, wherein the total content (B+C) of the components (B) and (C) is 2.5 to 20 parts by mass per 100 parts by mass of the component (A).

4. 3. The rubber composition for a rubber layer according to claim 1, wherein a mass ratio (B / C) of the component (B) to the component (C) is 0.25 to 1.

5.

5. 3. The rubber composition for the rubber layer according to claim 1, wherein the component (C) is an aromatic bismaleimide compound.

6. 3. The rubber composition for a rubber layer according to claim 1, wherein the component (B) is a tackifier further comprising a structural unit derived from an aliphatic monomer.

7. 3. The rubber composition for the rubber layer according to claim 1, wherein the multi-layer hose is a multi-layer hose having a multi-layer structure formed by laminating a rubber layer and a resin layer.

8. 8. The rubber composition for a rubber layer according to claim 7, wherein the resin layer is a reinforcing thread layer comprising reinforcing threads including at least one selected from the group consisting of polyamide threads, polyethylene terephthalate threads, and polyvinyl alcohol threads.

9. 3. A multi-layer hose comprising a laminate structure formed by laminating a rubber layer made of a vulcanizate of the rubber composition for the rubber layer according to claim 1 or 2 and a resin layer.

10. 10. The laminated hose according to claim 9, wherein the resin layer is a reinforcing fiber layer.

11. 3. A laminated hose for automobiles, comprising a laminated structure obtained by laminating in this order: a first rubber layer made of a vulcanizate of the rubber composition for the rubber layer according to claim 1 or 2; a reinforcing thread layer; and a second rubber layer made of a vulcanizate of the rubber composition for the rubber layer containing the components (A) and (D).

12. 12. The laminated hose for automobiles according to claim 11, wherein the second rubber layer is a rubber layer made of a vulcanizate of a rubber composition for the rubber layer further containing the component (B) and / or the component (C).

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