Rubber composition, rubber-metal laminate, gasket, and method for manufacturing rubber-metal laminate

Abstract

The present invention can realize: a rubber composition which can prevent metal corrosion caused by a sulfur component and can give a gasket having excellent heat resistance; a rubber / metal layered product; a gasket; and a method for producing a rubber / metal layered product. This rubber composition contains 100 parts by mass of an ethylene-acrylate rubber; 1-200 parts by mass of carbon black; 0.1-20 parts by mass of an amine-based crosslinking agent; and 1-50 parts by mass of a foaming agent.

Description

[Technical Field]

[0001] The present invention relates to a rubber composition, a rubber metal laminate, a gasket, and a method for manufacturing a rubber metal laminate, and more particularly to a rubber composition containing ethylene acrylate rubber, a rubber metal laminate, a gasket, and a method for manufacturing a rubber metal laminate. [Background technology]

[0002] In recent years, rubber compositions containing nitrile rubbers such as NBR, H-NBR, and modified NBR have been used as gasket materials for automobiles and other vehicles. These rubber compositions often contain sulfur components, such as sulfur and sulfur compounds, as sulfur-based crosslinking agents, crosslinking accelerators, and antioxidants. However, rubber compositions containing nitrile rubber and sulfur components can release sulfur, which can corrode metals such as electrical components. Therefore, gasket materials (see, for example, Patent Document 1) and gasket materials (see, for example, Patent Document 2) that crosslink nitrile rubber without using sulfur components have been proposed.

[0003] In the gasket material described in Patent Document 1, nitrile rubber is crosslinked using a quinoid crosslinking agent, thereby preventing metal corrosion of electrical components and the like due to sulfur components in the gasket material when the gasket material is used in the electrical components. In addition, in the gasket material described in Patent Document 2, carboxyl group-modified nitrile rubber is vulcanized using an epoxy compound as a crosslinking agent, thereby preventing metal corrosion of electronic components and the like due to sulfur components in the gasket material when the gasket material is used in the electronic components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-99558 [Patent Document 2] International Publication No. 2013 / 011918 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in nitrile rubber materials, peroxide-based crosslinking agents containing peroxides are also used to crosslink the nitrile rubber. However, rubber compositions containing peroxide-based crosslinking agents cannot be used to manufacture gaskets with foam rubber layers, which generally require oven vulcanization, because the peroxide reacts with oxygen in the air. Furthermore, while the gasket material described in Patent Document 1 and the gasket material described in Patent Document 2 can prevent corrosion of electronic components and the like due to sulfur components, the use of nitrile rubber as the rubber material does not necessarily provide sufficient heat resistance, and they may not be able to be used in environments above 100°C.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a rubber composition, a rubber-metal laminate, a gasket, and a method for manufacturing a rubber-metal laminate that can prevent metal corrosion due to sulfur components and that can produce a gasket with excellent heat resistance. [Means for solving the problem]

[0007] The rubber composition according to the present invention is characterized by comprising 100 parts by mass of ethylene acrylate rubber, 1 part by mass or more and 200 parts by mass or less of carbon black, 0.1 part by mass or more and 20 parts by mass or less of an amine-based crosslinking agent, and 1 part by mass or more and 50 parts by mass or less of a foaming agent.

[0008] According to the rubber composition of the present invention, the ethylene acrylate rubber is crosslinked using an amine-based crosslinking agent, eliminating the need for a sulfur component in the crosslinking of the ethylene acrylate rubber. As a result, the content of sulfur components in the crosslinked rubber composition is significantly reduced compared to when a sulfur-based crosslinking agent is used. This prevents corrosion of metal components due to the liberation of sulfur components in the crosslinked rubber composition. Furthermore, since the rubber composition contains ethylene acrylate rubber, which has better heat resistance than nitrile rubber, as a rubber component, it can achieve excellent heat resistance, allowing it to be used in environments above 100°C. Furthermore, the rubber composition can prevent reaction between the amine-based crosslinking agent and air, thereby ensuring sufficient crosslinking of the ethylene acrylate rubber and preventing adhesion of the crosslinked rubber composition to metal components, even when oven crosslinking is performed. As a result, the rubber composition can prevent metal corrosion due to sulfur components and can produce a gasket with excellent heat resistance.

[0009] In the rubber composition, the amine-based crosslinking agent preferably contains a diamine. This configuration allows the ethylene acrylate rubber to be efficiently crosslinked via the amine-based crosslinking agent, thereby further improving the heat resistance of the rubber composition after crosslinking.

[0010] In the rubber composition, the foaming agent is preferably at least one selected from the group consisting of a thermal expansion foaming agent and a thermal decomposition foaming agent. With this configuration, the rubber composition is efficiently foamed during crosslinking by oven crosslinking, making it possible to obtain a foamed rubber layer with excellent heat resistance.

[0011] The rubber metal laminate according to the present invention is characterized by comprising a metal member and a foamed rubber layer provided on the metal member and formed by crosslinking the above-mentioned rubber composition.

[0012] In the rubber metal laminate according to the present invention, the ethylene acrylate rubber is crosslinked using an amine-based crosslinking agent, eliminating the need for a sulfur component to crosslink the ethylene acrylate rubber in the rubber composition. This significantly reduces the sulfur content in the foamed rubber layer after crosslinking compared to when a sulfur-based crosslinking agent is used, preventing corrosion of metal components due to the liberation of sulfur components in the foamed rubber layer after crosslinking. Furthermore, since the rubber metal laminate contains ethylene acrylate rubber, which has better heat resistance than nitrile rubber, as the rubber component, it achieves excellent heat resistance, allowing it to be used in environments above 100°C. Furthermore, the rubber metal laminate can prevent reaction between the amine-based crosslinking agent and air, ensuring sufficient crosslinking of the ethylene acrylate rubber even when the rubber composition is oven-crosslinked, preventing adhesion of the crosslinked rubber composition to metal components. These features allow the rubber metal laminate to prevent metal corrosion due to sulfur components and to produce a gasket with excellent heat resistance.

[0013] In the rubber metal laminate, it is preferable that no corrosion occurs on the brass plate, steel plate, or stainless steel plate in a corrosion and stickiness test in accordance with JIS B2403, Section 9.2. This configuration makes it possible for the rubber metal laminate to prevent corrosion of metal members and the like due to components liberated from the foamed rubber layer.

[0014] In the rubber metal laminate, it is preferable that the change in pencil hardness of the foamed rubber layer before and after heat aging for 24 hours at 150°C in a scratch hardness test (pencil method) in accordance with JIS K5600-5-4 is 3 points or less. With this configuration, the rubber metal laminate can have a foamed rubber layer with excellent heat resistance.

[0015] A gasket according to the present invention is characterized by including the above-described rubber metal laminate.

[0016] According to the gasket of the present invention, the ethylene acrylate rubber is crosslinked using an amine-based crosslinking agent, eliminating the need for a sulfur component to crosslink the ethylene acrylate rubber in the rubber composition. This significantly reduces the sulfur component content in the crosslinked foamed rubber layer compared to when a sulfur-based crosslinking agent is used, thereby preventing corrosion of metal components due to the liberation of sulfur components in the crosslinked foamed rubber layer. Furthermore, since the gasket contains ethylene acrylate rubber, which has better heat resistance than nitrile rubber, as the rubber component, it can achieve excellent heat resistance, allowing it to be used in environments above 100°C. Furthermore, the gasket can prevent reaction between the amine-based crosslinking agent and air, thereby ensuring sufficient crosslinking of the ethylene acrylate rubber even when the rubber composition is oven-crosslinked, preventing adhesion of the crosslinked rubber composition to metal components. These features enable the gasket to prevent metal corrosion due to sulfur components and to have excellent heat resistance.

[0017] The method for manufacturing a rubber metal laminate according to this embodiment is characterized by including a rubber composition preparation step of mixing 100 parts by mass of ethylene acrylate rubber, 1 part by mass or more and 200 parts by mass or less of carbon black, 0.1 part by mass or more and 20 parts by mass or less of an amine-based crosslinking agent, and 1 part by mass or more and 50 parts by mass or less of a foaming agent to obtain a rubber composition, and a crosslinking step of applying the rubber composition onto a metal member and crosslinking it by oven crosslinking to obtain a rubber metal laminate.

[0018] According to the manufacturing method of a rubber metal laminate of the present invention, the ethylene acrylate rubber is crosslinked using an amine-based crosslinking agent, eliminating the need for a sulfur component to crosslink the ethylene acrylate rubber in the rubber composition. As a result, the resulting rubber metal laminate has a significantly lower sulfur content in the foamed rubber layer after crosslinking than when a sulfur-based crosslinking agent is used. This prevents corrosion of metal components due to the liberation of sulfur components in the foamed rubber layer after crosslinking. Furthermore, since the resulting rubber metal laminate contains ethylene acrylate rubber, which has better heat resistance than nitrile rubber, it has excellent heat resistance, allowing it to be used in environments above 100°C. Furthermore, the resulting rubber metal laminate can prevent reaction between the amine-based crosslinking agent and air, ensuring sufficient crosslinking of the ethylene acrylate rubber even when the rubber composition is oven-crosslinked, preventing adhesion of the crosslinked rubber composition to metal components. As a result, the manufacturing method of a rubber metal laminate can prevent metal corrosion due to sulfur components and produce a rubber metal laminate that can provide a gasket with excellent heat resistance. [Effects of the Invention]

[0019] According to the present invention, it is possible to realize a rubber composition, a rubber-metal laminate, a gasket, and a method for manufacturing a rubber-metal laminate that can prevent metal corrosion due to sulfur components and provide a gasket with excellent heat resistance. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is an explanatory diagram of a corrosion and stickiness test according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. However, the present invention is not limited to the following embodiments and can be modified as needed.

[0022] (Rubber composition) The rubber composition contains 100 parts by mass of ethylene acrylate rubber, 1 part by mass to 200 parts by mass of carbon black, 0.1 part by mass to 20 parts by mass of an amine-based crosslinking agent, and 1 part by mass to 50 parts by mass of a foaming agent. Each component of the rubber composition will be described in detail below.

[0023] Ethylene acrylate rubber (AEM) is a material with good heat and cold resistance, and is a copolymer of ethylene and acrylic esters. Ethylene acrylate rubber includes a binary copolymer of ethylene and acrylic esters crosslinked with a peroxide-based crosslinking agent, and a ternary copolymer of ethylene, acrylic esters, and a carboxyl-containing unsaturated compound. In this embodiment, a ternary copolymer of ethylene, acrylic esters, and a carboxyl-containing unsaturated compound crosslinked with an amine-based crosslinking agent is used as the ethylene acrylate rubber. This ethylene acrylate rubber is a special crosslinked acrylic rubber material in which the carboxyl-containing unsaturated compound serves as the crosslinking point.

[0024] Examples of acrylic esters that can be used include alkyl acrylates having an alkyl group with 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, and n-octyl methacrylate, and alkoxyalkyl acrylates having an alkoxyalkyl group with 1 to 8 carbon atoms, such as methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, n-butoxyethyl acrylate, and ethoxypropyl acrylate. Generally, acrylic esters with a longer alkyl group chain length are advantageous in terms of cold resistance, while shorter alkyl group chain lengths are advantageous in terms of oil resistance. As the alkyl acrylate, for example, ethyl acrylate and n-butyl acrylate are preferred from the viewpoint of the balance between oil resistance and cold resistance.

[0025] Examples of the carboxyl group-containing unsaturated compound include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, and itaconic acid, as well as monoalkyl esters such as methyl, ethyl, propyl, isopropyl, n-butyl, and isobutyl of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid. Among these, preferred carboxyl group-containing unsaturated compounds are maleic acid mono-n-butyl ester, fumaric acid monoethyl ester, and fumaric acid mono-n-butyl ester.

[0026] The ethylene acrylate rubber may be further copolymerized with other copolymerizable ethylenically unsaturated monomers, such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, acrylonitrile, methacrylonitrile, acrylic acid amide, vinyl acetate, cyclohexyl acrylate, benzyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, ethylene, propylene, piperylene, butadiene, isoprene, and pentadiene.

[0027] The ethylene acrylate rubber can be obtained by copolymerizing the above-mentioned ethylene, acrylic acid esters, and carboxyl group-containing unsaturated compounds, as well as other copolymerizable ethylenically unsaturated monomer components, by a known polymerization method such as emulsion polymerization, suspension polymerization, solution polymerization, or bulk polymerization.

[0028] As the ethylene acrylate rubber, for example, commercially available products such as "Vamac (registered trademark) GLS" and "Vamac G" (manufactured by DuPont Dow Elastomers) may be used.

[0029] The amount of ethylene acrylate rubber in the rubber composition is preferably 40% by mass or more and 90% by mass or less, more preferably 45% by mass or more and 85% by mass or less, and even more preferably 50% by mass or more and 80% by mass or less, from the viewpoint of improving the sealing properties and heat resistance of a gasket obtained from the rubber composition.

[0030] Carbon black is compounded in rubber compositions as a filler and a reinforcing material. Examples of carbon black include hard carbons such as super abrasion furnace (SAF) carbon black, intermediate super abrasion furnace (ISAF) carbon black, high abrasion furnace (HAF) carbon black, and easy processing channel (EPC) carbon black, as well as soft carbons such as extra conductive furnace (XCF) carbon black, fast extruding furnace (FEF) carbon black, general purpose furnace (GPF) carbon black, high modulus furnace (HMF) carbon black, semi-reinforcing furnace (SRF) carbon black, fine thermal (FT) carbon black, and medium thermal (MT) carbon black. These carbon blacks may be used alone or in combination of two or more. Among these, soft carbon is preferred as the carbon black, and among the soft carbons, medium-reinforcing carbon black and medium-particle pyrolytic carbon black are more preferred. As the carbon black, commercially available medium-particle pyrolytic carbon black such as the product name "THERMAX (registered trademark) N990 LSR" (manufactured by Cancarb Co., Ltd.) may be used, or commercially available medium-particle reinforcing carbon black such as the product name "HTC#SS" (manufactured by Nippon Steel Carbon Co., Ltd.) and the product name "ASAHI#50HG" (manufactured by Asahi Carbon Co., Ltd.) may be used.

[0031] From the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition, the amount of carbon black to be compounded is 1 part by mass or more and 200 parts by mass or less, preferably 5 parts by mass or more and 150 parts by mass or less, more preferably 10 parts by mass or more and 100 parts by mass or less, and even more preferably 15 parts by mass or more and 80 parts by mass or less, per 100 parts by mass of ethylene acrylate.

[0032] From the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition, the amount of carbon black to be compounded is preferably 5% by mass or more and 60% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, relative to the total mass of the rubber composition.

[0033] Furthermore, when the carbon black is medium-grain pyrolytic carbon, the amount of carbon black to be compounded is preferably 5 parts by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 30 parts by mass or less, and even more preferably 15 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of ethylene acrylate, from the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition.

[0034] When the carbon black is medium-grain pyrolytic carbon, the amount of carbon black blended is preferably 2.5% by mass or more and 40% by mass or less, more preferably 7.5% by mass or more and 20% by mass or less, and even more preferably 10% by mass or more and 17.5% by mass or less, based on the total mass of the rubber composition, from the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition.

[0035] Furthermore, when the carbon black is medium reinforcing carbon, the amount of carbon black compounded is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 25 parts by mass or more and 100 parts by mass or less, and even more preferably 45 parts by mass or more and 65 parts by mass or less, per 100 parts by mass of ethylene acrylate, from the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition.

[0036] When the carbon black is medium reinforcing carbon, the amount of carbon black mixed is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, relative to the total mass of the rubber composition, from the viewpoint of improving the sealing properties and heat resistance of the rubber metal laminate obtained from the rubber composition.

[0037] <Crosslinking agent> The crosslinking agent (vulcanizing agent) forms crosslinked bonds between the ethylene acrylate rubber. In this embodiment, an amine-based crosslinking agent is used as the crosslinking agent. As the amine-based crosslinking agent, diamines are preferred from the viewpoint of being able to easily form a crosslinked structure with the carboxyl groups, which are crosslinking points derived from the carboxyl group-containing unsaturated compound contained in the ethylene acrylate rubber.

[0038] The diamines may be aliphatic or aromatic. Examples of the diamines include hexamethylenediamine, hexamethylenediamine carbamate, N,N'-dicinnamylidene-1,6-hexanediamine, 4,4'-methylenebis(cyclohexylamine)carbamate, 4,4'-methylenedianiline, 4,4'-oxyphenyldiphenylamine, m-phenylenediamine, p-phenylenediamine, 4,4'-methylenebis(o-chloroaniline), 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl. ether, 4,4'-(m-phenylenediisopropylidene)dianiline, 4,4'-(p-phenylenediisopropylidene)dianiline, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminobenzanilide, 4,4'-bis(4-aminophenoxy)biphenyl, m-xylylenediamine, p-xylylenediamine, hexamethylenediamine-cinnamaldehyde adduct, and hexamethylenediamine-dibenzoate salt. Among these, the amine-based crosslinking agent is preferably at least one alkylenediamine selected from the group consisting of hexamethylenediamine carbamate, N,N'-dicinnamylidene-1,6-hexanediamine, 4,4'-methylenebis(cyclohexylamine) carbamate, and 4,4'-diaminodiphenyl ether, and more preferably an alkylenediamine containing hexamethylenediamine carbamate. Furthermore, examples of commercially available amine-based crosslinking agents that can be used include Cheminox AC6-66 (hexamethylenediamine carbamate) (manufactured by Unimatec Corporation), Diak No. 1 (hexamethylenediamine carbamate) (manufactured by DuPont Dow Elastomers), Diak No. 3: N,N'-dicinnamylidene-1,6-hexanediamine (manufactured by DuPont Dow Elastomers), Diak No. 4 (4,4'-methylenebis(cyclohexylamine)carbamate) (manufactured by DuPont Dow Elastomers), and DADPE: (4,4'-diaminodiphenyl ether) (manufactured by Sun Chemical).

[0039] From the viewpoint of improving the crosslinking density and thereby improving the heat resistance of the rubber composition, the amount of the amine-based crosslinking agent to be compounded is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 7.5 parts by mass or less, relative to 100 parts by mass of the ethylene acrylate rubber.

[0040] Furthermore, from the viewpoint of improving the crosslinking density and improving the heat resistance of the rubber composition, the amount of the amine-based crosslinking agent added is preferably 0.5% by mass or more and 10% by mass or less, more preferably 0.75% by mass or more and 5% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less, per 100 parts by mass of ethylene acrylate rubber, relative to the total mass of the rubber composition.

[0041] The amine-based crosslinking accelerator accelerates the formation of a crosslinking reaction of ethylene acrylate rubber by the amine-based crosslinking agent. Examples of the amine-based crosslinking accelerator include tertiary amine complexes adsorbed onto an amorphous silica carrier. As the amine-based crosslinking accelerator, for example, commercially available products such as "Vulcofac (registered trademark) ACT-55 (aminated derivative: tertiary amine complex adsorbed onto an amorphous silica carrier)" (manufactured by DuPont) may be used.

[0042] For example, from the viewpoint of improving the crosslink density and thereby improving the heat resistance of the rubber composition, the amount of the amine-based crosslinking accelerator to be compounded is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the ethylene acrylate rubber.

[0043] The amount of the amine-based crosslinking accelerator to be added is, for example, preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and even more preferably 0.75% by mass or more and 3% by mass or less, relative to the total mass of the rubber composition, from the viewpoint of improving the crosslink density and thereby improving the heat resistance of the rubber composition.

[0044] As the foaming agent, various foaming agents can be used as long as the effects of the present invention are achieved. Examples of the foaming agent include various thermally expandable foaming agents and various thermally decomposable foaming agents. Examples of the thermally expandable foaming agent include thermally expandable microcapsules encapsulating a low-boiling-point hydrocarbon expanding agent. Examples of the thermally decomposable foaming agent include chemical foaming agents containing thermally decomposable organic or inorganic compounds. Examples of the chemical foaming agent include chemical foaming agents containing organic compounds such as azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, and N,N'-dinitrosopentamethylenetetramine, as well as chemical foaming agents containing inorganic compounds such as sodium bicarbonate. Among these, thermally expandable microcapsules and chemical foaming agents containing azodicarbonamide are preferred as foaming agents from the viewpoint of improving the sealing properties and heat resistance of gaskets obtained from the rubber composition.

[0045] As the foaming agent, for example, commercially available products such as "Advancell EM304 (thermally expandable microcapsules)" (manufactured by Sekisui Chemical Co., Ltd.) and "Vinylhole AC#3 (azodicarbonamide)" (manufactured by Eiwa Chemical Co., Ltd.) may be used.

[0046] The amount of foaming agent to be added is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 45 parts by mass or less, and even more preferably 7.5 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of ethylene acrylate rubber, from the viewpoint of efficiently foaming the rubber composition during crosslinking and obtaining a foamed rubber layer that is excellent in sealing properties and heat resistance of a gasket using the rubber composition.

[0047] The amount of foaming agent added is preferably 1% by mass or more and 50% by mass or less, more preferably 2.5% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 25% by mass or less, relative to the total mass of the rubber composition, from the viewpoint of efficiently foaming the rubber composition during crosslinking and obtaining a foamed rubber layer that has excellent sealing properties and heat resistance for a gasket using the rubber composition.

[0048] Furthermore, the rubber composition may contain fillers such as calcium carbonate and silica, as required. As the calcium carbonate, various calcium carbonates such as heavy calcium carbonate and synthetic calcium carbonate can be used.

[0049] Furthermore, the rubber composition may contain, as needed, auxiliary agents commonly used in the rubber industry, such as zinc oxide, plasticizers, stearic acid, antioxidants, and paraffin wax.

[0050] The plasticizer functions as a processing aid that appropriately reduces the viscosity of the rubber composition to improve processability. Examples of the plasticizer include commercially available products such as "Mezamol (registered trademark)" (manufactured by Lanxess). The blending amount of the plasticizer is, for example, 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the rubber component.

[0051] As the stearic acid, for example, a commercially available product such as "DTST" (manufactured by Miyoshi Oil & Fats Co., Ltd.) may be used. The compounding amount of stearic acid is, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0052] As the antiaging agent, for example, a commercially available product such as "Nocrac (registered trademark) CD" (4,4'-bis(α,α-dimethylbenzyl)diphenylamine) may be used. The amount of the antiaging agent mixed is, for example, 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0053] (Rubber-metal laminate) Next, a rubber metal laminate according to this embodiment will be described. The rubber metal laminate according to this embodiment comprises a metal member and a foamed rubber layer formed on the metal member by crosslinking the rubber composition. This rubber metal laminate can be suitably used as a sealing member for various gaskets and the like.

[0054] In the rubber metal laminate according to this embodiment, the foamed rubber layer preferably exhibits a pencil hardness change of 3 points or less in a scratch hardness test (pencil method) in accordance with JIS K5600-5-4 before and after heat aging at 150°C for 24 hours. This enables the rubber metal laminate to have a foamed rubber layer with excellent heat resistance. Here, the hardness change refers to the amount of change in pencil hardness. For example, if the pencil hardness before heat aging at 150°C for 24 hours is 6B and the pencil hardness after heat aging at 150°C for 24 hours is 5B, the hardness change is considered to be 1 point. Also, if the pencil hardness before heat aging at 150°C for 24 hours is F and the pencil hardness after heat aging at 150°C for 24 hours is H, the hardness change is considered to be 1 point. The hardness change in the pencil hardness is more preferably 2 points or less, and even more preferably 1 point or less.

[0055] From the viewpoint of improving the sealing properties of sealing members such as gaskets using the rubber metal laminate, the foaming ratio of the foamed rubber layer is preferably 2 times or more, more preferably 2.5 times or more, and even more preferably 3 times or more, and is preferably 20 times or less, more preferably 10 times or less, and even more preferably 7.5 times or less. The foaming ratio here is calculated based on the following formula (1): Foaming ratio = (thickness of rubber metal laminate after cross-linking - thickness of steel plate) / (thickness of rubber metal laminate before cross-linking - thickness of steel plate) Formula (1)

[0056] In the rubber laminate according to this embodiment, it is preferable that no corrosion occurs on the brass plate, steel plate, or stainless steel plate in a corrosion and stickiness test in accordance with JIS B2403, Section 9.2. This makes it possible for the rubber metal laminate to prevent corrosion of metal members and the like due to components liberated from the foamed rubber layer.

[0057] Furthermore, in the rubber laminate according to this embodiment, it is preferable that no transfer (stickiness) occurs to the brass plate, steel plate, or stainless steel plate in a corrosion and stickiness test in accordance with JIS B2403, Section 9.2. This makes it possible for the rubber metal laminate to prevent the transfer of rubber components from the foamed rubber layer to metal members, etc. The various components of the rubber metal laminate according to this embodiment will be described in detail below.

[0058] Examples of metal members that can be used include metal plates of iron, stainless steel, aluminum, magnesium, galvanized steel, and copper. Examples of iron that can be used include cold-rolled steel plates (SPCC: Steel Plate Cold Commercial), high-tensile steel plates, and mild steel plates. Examples of stainless steel that can be used include ferritic, martensitic, and austenitic stainless steel plates. Specific examples of stainless steel include SUS304, SUS301, SUS301H, and SUS430. Examples of aluminum that can be used include aluminum plates and aluminum die-cast plates.

[0059] The metal member is preferably used after its surface has been degreased by alkaline degreasing treatment, etc. Furthermore, the metal member is used after its surface has been roughened, if necessary, by shot blasting, Scotch Bride (registered trademark), hairline finishing, dull finishing, etc.

[0060] The metal member is preferably subjected to a surface treatment (surface treatment) on the surface to be bonded to the adhesive. The surface treatment is not particularly limited, and known surface treatments can be used. When using iron materials such as cold-rolled steel sheets and high-tensile steel sheets or stainless steel materials as the metal member, preferred surface treatments include chemical conversion treatments using various chemical conversion treatment agents, and various plating methods such as electroplating and hot-dip plating with metals such as zinc. Examples of chemical conversion treatment agents for metal members include phosphate-based treatment agents such as zinc phosphate treatment agents and iron phosphate treatment agents, and paint-type chromate treatment agents. From the viewpoint of environmental protection, chromium-free chemical conversion treatment agents that are substantially free of chromium are preferred.

[0061] The surface treatment of metal members with a chemical conversion treatment agent is carried out by contacting the chemical conversion treatment agent with the metal member by a known liquid contact method such as atomization, spraying, immersion, brush application, roll coating, etc. In the case of reactive chemical conversion treatment agents, it is necessary to ensure the time and temperature required for the reaction.

[0062] In addition to or instead of the surface treatment, it is preferable that a primer layer be formed on the metal member of the rubber metal laminate. By performing the surface treatment or providing the primer layer, the adhesion between the rubber layer and the metal member in the rubber metal laminate is improved, and the heat resistance and water resistance of the rubber metal laminate can be significantly improved. Furthermore, by performing the surface treatment or forming the primer layer, the rubber metal laminate can be suitably used as a gasket, which is a laminated composite metal formed by laminating the rubber metal laminate with another metal plate or the like.

[0063] The primer layer can be formed using inorganic compounds such as silicon compounds, compounds of metals such as titanium, zirconium, vanadium, aluminum, molybdenum, tungsten, manganese, zinc, and cerium, and oxides thereof, and organic compounds such as silicone resins, phenolic resins, epoxy resins, and polyurethanes. The primer layer can be formed using a commonly available primer solution, or using a primer solution prepared by various known techniques.

[0064] The primer layer is provided using a primer solution prepared by dissolving or dispersing raw materials containing the above-mentioned inorganic or organic compounds in an organic or aqueous solvent. Usable organic solvents include, for example, alcohols such as methanol, ethanol, and isopropyl alcohol, and ketones such as acetone and methyl ethyl ketone. The primer solution may be prepared as an aqueous solution using an aqueous solvent, as long as the solution stability is maintained.

[0065] The obtained primer solution is applied to a metal plate by spraying, dipping, brushing, roll coating, etc. Then, a primer layer is provided by drying the primer solution applied to the metal plate at room temperature or with hot air, or by baking.

[0066] The adhesive bonds the rubber layer and the metal member. Examples of adhesives that can be used include commercially available adhesives such as phenolic resins, epoxy resins, polyurethane resins, and silanes. These adhesives can be selected appropriately depending on the intended use of the rubber-metal laminate.

[0067] In the rubber metal laminate, the metal plate and the rubber layer are preferably bonded via at least one resin selected from the group consisting of phenolic resin and epoxy resin, which improves the adhesiveness between the metal plate and the rubber layer, thereby further improving the sealing performance of the object to be sealed when used in various gaskets, etc.

[0068] As the phenolic resin, for example, a novolac type phenolic resin or a resol type phenolic resin is used. The novolac type phenolic resin and the resol type phenolic resin may be used alone or in combination of two or more. Furthermore, as the adhesive, an adhesive containing two types of phenolic resins, a novolac type phenolic resin and a resol type phenolic resin, and an uncrosslinked nitrile rubber may be used.

[0069] The novolac phenolic resin is obtained by condensation reaction of a phenol with formaldehyde in the presence of an acid catalyst. Examples of phenols that can be used include those having two or three substitutable hydrogen atoms at at least one of the ortho- and p-positions relative to the phenolic hydroxyl group, such as phenol, p-cresol, m-cresol, p-tert-butylphenol, p-phenylphenol, and bisphenol A. These phenolic resins may be used alone or in combination. Examples of acid catalysts that can be used include oxalic acid, hydrochloric acid, and maleic acid. Among these, the novolac phenolic resin is preferably one having a melting point of 80°C or higher and 150°C or lower, from the viewpoint of improving adhesion between the metal plate and the rubber layer, and more preferably one having a melting point of 120°C or higher obtained using m-cresol and formaldehyde.

[0070] Resole-type phenolic resins are those obtained by condensation reaction of phenols and formaldehyde in the presence of a base catalyst. Examples of phenols that can be used include phenol, p-cresol, m-cresol, p-tert-butylphenol, p-phenylphenol, and bisphenol A, which have two or three substitutable hydrogen atoms at at least one of the ortho- and p-positions relative to the phenolic hydroxyl group. These phenolic resins may be used alone or in combination of two or more. Examples of base catalysts that can be used include ammonia, alkali metal hydroxides such as sodium hydroxide, magnesium hydroxide, and sodium carbonate.

[0071] Examples of epoxy resins include bisphenol A, cresol novolac, biphenyl, and brominated epoxy resins. These epoxy resins may be used alone or in combination of two or more. Among these epoxy resins, bisphenol A epoxy resins and cresol novolac epoxy resins are preferred from the viewpoints of easy commercial availability and excellent heat resistance. As bisphenol A epoxy resins, for example, commercially available products manufactured by DIC Corporation under the trade names "EPICLON 860," "EPICLON 1055," "EPICON 2050," and "EPICLON 3050," and trade names "EPICLON 4050," "EPICLON 7050," and "EPICLON HM-091" may be used. Furthermore, examples of commercially available cresol novolac epoxy resins that may be used include products manufactured by DIC Corporation under the trade names "EPICLON N-660," "EPICLON N-670," "EPICLON N-680," and "EPICLON N-690."

[0072] The various adhesives described above are used as a solution dissolved in an organic solvent. Examples of the organic solvent include ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatic hydrocarbons such as toluene and xylene. These organic solvents may be used alone or in combination of two or more.

[0073] The adhesive is preferably blended in a ratio of 10 to 1,000 parts by mass, more preferably 60 to 400 parts by mass, of resol phenolic resin relative to 100 parts by mass of novolac phenolic resin. By using 1,000 parts by mass or less of resol phenolic resin relative to 100 parts by mass of novolac phenolic resin, it is possible to prevent a decrease in the adhesiveness of the rubber layer, and by using 10 parts by mass or more, it is possible to prevent a decrease in the adhesiveness to the surface of the metal member.

[0074] From the viewpoint of improving the adhesion between the metal member and the rubber layer, the adhesive is preferably provided on a metal plate on which a primer layer has been formed. The adhesive layer may be provided as a single layer or as multiple layers. The adhesive layer may have a multi-stage structure in which a phenolic adhesive layer containing an organic metal compound is formed on the primer layer provided on the metal member, and then a phenolic adhesive layer is provided on the adhesive layer. By providing such a multi-stage adhesive layer, it is possible to further strengthen the adhesion between the primer layer and the rubber layer.

[0075] The adhesive is prepared as an adhesive solution with a solids concentration of 1% by mass to 10% by mass using a ketone-based organic solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, or a mixture thereof. The adhesive solution is applied to a metal member, and then dried and baked for 1 minute to 30 minutes at a temperature of 100°C to 250°C to form an adhesive layer. The coating amount of the adhesive is 50 mg / m after drying and baking after application. 2 More than 2000mg / m 2 The thickness is preferably in the following range: The adhesive is preferably applied so that the thickness of the adhesive layer after drying is 0.5 μm or more and 5 μm or less.

[0076] The foamed rubber layer may contain other rubber components as long as the effects of the present invention are achieved. Examples of other rubber components include various rubber materials such as nitrile butadiene rubber (NBR), which is an acrylonitrile-butadiene copolymer, hydrogenated nitrile rubber (H-NBR), which is obtained by hydrogenating the unsaturated bond portion of nitrile rubber, modified nitrile rubber, and fluororubber.

[0077] From the viewpoint of obtaining sufficient sealing properties and heat resistance when used as a gasket, the foamed rubber layer preferably has a thickness after crosslinking of 10 μm or more and 700 μm or less, more preferably 20 μm or more and 600 μm or less, and even more preferably 30 μm or more and 500 μm or less.

[0078] The rubber metal laminate according to the above embodiment is manufactured using a solution of a rubber composition prepared by blending a metal member such as a stainless steel plate with a rubber component, carbon black, an amine-based crosslinking agent, and a foaming agent, and optionally blending a crosslinking accelerator, calcium carbonate, silica, plasticizer, and various auxiliary agents, and kneading the resulting mixture in a sealed mixer such as an Intermix, kneader, or Banbury mixer, or an open roll mixer, and then dissolving the resulting mixture in an organic solvent. The rubber metal laminate is manufactured by applying the rubber composition to a metal member, surface-treated as needed, via an adhesive layer, and then crosslinking the rubber composition in an oven at a temperature of 160°C to 250°C for 0.5 to 30 minutes to form a foamed rubber layer. To prevent adhesion of the rubber, the rubber metal laminate may be coated with a resin-based or graphite-based coating agent on the rubber layer.

[0079] The method for applying the rubber composition to the metal member is not particularly limited as long as it can apply the rubber composition to the metal member, and examples of the method include spraying, dipping, roll coating, and dispenser methods.

[0080] When producing the rubber composition and when applying it to a metal member, an organic solvent may be added to the rubber composition to adjust the viscosity, if necessary. The organic solvent is not particularly limited as long as it can adjust the viscosity of the rubber composition to the desired viscosity. Examples of the organic solvent include ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone, aromatic hydrocarbon-based solvents such as toluene, and ester-based solvents such as ethyl acetate. These organic solvents may be used alone or in combination of two or more.

[0081] As described above, according to the above embodiment, the ethylene acrylate rubber is crosslinked using an amine-based crosslinking agent, eliminating the need for a sulfur component in the crosslinking of the ethylene acrylate rubber. This significantly reduces the sulfur content in the crosslinked rubber composition compared to when a sulfur-based crosslinking agent is used, thereby preventing corrosion of metal components due to the liberation of sulfur components in the crosslinked rubber composition. Furthermore, since the rubber composition contains ethylene acrylate rubber, which has better heat resistance than nitrile rubber, as a rubber component, it achieves excellent heat resistance, allowing it to be used in environments above 100°C, making it applicable to heat-resistant applications. Furthermore, the rubber metal laminate can prevent the amine-based crosslinking agent from reacting with air, thereby sufficiently crosslinking the ethylene acrylate rubber even when the rubber composition is oven-crosslinked, preventing adhesion of the crosslinked rubber composition to metal components. Furthermore, the rubber metal laminate has a foamed rubber layer formed from a rubber composition containing a foaming agent. The numerous bubbles present in the foamed rubber layer increase the compressibility when used in a gasket, providing excellent sealing performance for flanges with rough surface roughness and under low surface pressure. As a result, the rubber composition can prevent metal corrosion due to the sulfur component, and a gasket with excellent heat resistance can be obtained. [Example]

[0082] The present invention will be described in more detail below based on examples conducted to clarify the effects of the present invention, but the present invention is not limited to the following examples and comparative examples.

[0083] The inventors of the present invention have fabricated rubber metal laminates according to the above-described embodiments, and have evaluated the fabricated rubber metal laminates by carrying out compression tests. The results of the investigations carried out by the inventors of the present invention will be described below.

[0084] Example 1 <Preparation of sample for foaming property evaluation> A 600 μm-thick cold-rolled steel plate (SPCC: Steel Plate Cold Commercial) was subjected to a chemical conversion treatment using zinc phosphate treatment. Next, a primer solution prepared by diluting a primer (Chemlock® AP133, manufactured by LOAD) with methanol to a solids content of 2% by mass was dip-applied to the chemically treated cold-rolled steel plate, followed by heat treatment at 200°C for 10 minutes to form a primer layer with a thickness of 1 μm or less on the cold-rolled steel plate. Next, a solution of 97% by mass of a phenolic resin-based adhesive (Sixon 715A, manufactured by Rohm and Haas Co.) and 3% by mass of a hexamethylenetetramine-containing curing agent B (Sixon 715B, manufactured by Rohm and Haas Co.) diluted to a solids concentration of 6% by mass with a mixed solvent of 440 parts by mass of methyl ethyl ketone and 110 parts by mass of methanol was dip-applied to the primer layer, followed by heat treatment at 170°C for 5 minutes to form an adhesive layer.

[0085] Next, 100 parts by mass of ethylene acrylate rubber (trade name "VAMAC (registered trademark) GLS", manufactured by DuPont), 20 parts by mass of carbon black A (medium-grain pyrolytic carbon black: trade name "THERMAX (registered trademark) N990 LSR", manufactured by Cancarb), 2 parts by mass of stearic acid (trade name "DTST", manufactured by Miyoshi Oil & Fats Co., Ltd.), 2 parts by mass of an antioxidant (4,4'-bis(α,α-dimethylbenzyl)diphenylamine: trade name "Nocrac (registered trademark) CD", manufactured by Lanxess AG), 2 parts by mass of an amine-based crosslinking agent (hexamethylenediamine carbamate: trade name "ChemiNox AC6-66", manufactured by Unimatec Co., Ltd.), 1.6 parts by mass of an amine-based crosslinking accelerator (tertiary amine complex adsorbed on an amorphous silica carrier: trade name "Valcofac ACT-55", manufactured by DuPont), and a thermal decomposition type blowing agent (azodicarbonamide: trade name "Vinihall" A rubber composition was obtained by kneading 30 parts by mass of "AC#3" (manufactured by Eiwa Kasei Co., Ltd.) using a kneader and open roll. The obtained rubber composition was dissolved in a mixed solvent of methyl ethyl ketone and toluene in a mass ratio of 2:8 to prepare a rubber composition solution with a solids concentration of the rubber composition of 25% by mass or more and 35% by mass or less. Next, the rubber composition solution was uniformly applied to the adhesive layer on one main surface of a cold-rolled steel plate, and then dried at 60°C for 5 minutes to prepare a sample for evaluating the foaming properties of the rubber metal laminate.

[0086] <Evaluation of foaming characteristics> The thickness of the entire rubber metal laminate and the thickness of the cold-rolled steel plate of the foaming property evaluation sample were measured before crosslinking, and then the sample was crosslinked at 200°C for 3 minutes, and the thickness of the entire rubber metal laminate after crosslinking was measured. The foaming ratio was calculated using the following formula (1). Foaming ratio = (thickness of rubber metal laminate after cross-linking - thickness of steel plate) / (thickness of rubber metal laminate before cross-linking - thickness of steel plate) Formula (1)

[0087] <Heat resistance evaluation> After crosslinking the foaming property evaluation sample, the pencil hardness was measured by hand in accordance with JIS K5600-5-4 "Mechanical properties of coating film - Scratch hardness (pencil method)" to evaluate heat resistance. Pencils with hardness ratings of 6B to 6H (manufactured by Mitsubishi Pencil Co., Ltd.) certified by the Japan Paint Certification Association were used. Pencil hardness was determined by the hardness classification, starting with the hardest pencil and gradually decreasing the pencil hardness until no scraping of the foam rubber layer occurred. In this example, since the rubber layer of the rubber metal laminate was foam rubber, the evaluation was based on the following criteria. When scratched with a pencil, a dent that simply leaves a white linear mark at the scratched area was determined not to be abrasion. When scratched with a pencil, if the scratched area was left with uneven scratches due to stick-slip, it was determined that the rubber had been scraped off. When scratched with a pencil, if the rubber at the scratched area peeled off, it was determined that the rubber had been scraped off. Scratch hardness was measured before and after a 24-hour thermal exposure at 150°C, and samples with a small change in pencil hardness due to thermal aging were judged to have good heat resistance. For example, if the hardness before aging was 6B and the hardness after aging was 3B, the hardness change was evaluated as +3 points. Heat resistance was evaluated based on the following evaluation criteria. ○: Hardness change is within +2 points ×: Hardness change is +3 points or more

[0088] <Corrosion and stickiness evaluation> A primer solution prepared by dip-coating a 200 μm-thick stainless steel plate (model number "SUS301H") with a primer (Chemlock (registered trademark) AP133, manufactured by LOAD) diluted with methanol to a solids content of 2% by mass, followed by heat treatment at 200 ° C for 10 minutes to form a primer layer on the cold-rolled steel plate. Next, a solution of 97% by mass of a phenolic resin adhesive (Sixon 715A, manufactured by Rohm and Haas) and 3% by mass of a hexamethylenetetramine-containing curing agent B (Sixon 715B, manufactured by Rohm and Haas) diluted to a solids concentration of 6% by mass with a mixed solvent of 440 parts by mass of methyl ethyl ketone and 110 parts by mass of methanol was dip-coated on the primer layer, followed by heat treatment at 170 ° C for 5 minutes to form an adhesive layer.

[0089] Next, the rubber composition solution used in preparing the sample for evaluating foaming properties was uniformly applied to the adhesive layer on one main surface of a stainless steel plate so that the thickness of the foamed rubber layer before crosslinking was 80 μm to 100 μm, and the resulting mixture was dried at 60° C. for 5 minutes. Next, the rubber composition solution was uniformly applied to the adhesive layer on the other main surface of the stainless steel plate so that the thickness of the foamed rubber layer before crosslinking was 80 μm to 100 μm, and the resulting mixture was dried at 60° C. for 5 minutes. Next, the stainless steel plate with the foamed rubber layer provided was crosslinked in an oven at 200° C. for 3 minutes to prepare a sample for evaluating the corrosion resistance and stickiness of the rubber metal laminate.

[0090] Corrosion and stickiness evaluations were performed in accordance with JIS B2403, Section 9.2, "Corrosion and Stickiness Test," which is used for V-packing. The prepared evaluation sample was cut into 25 mm wide and 50 mm long pieces to obtain four test pieces. The surfaces of three types of metal plates, 3 mm thick, 25 mm wide, and 50 mm long - brass plate (model number "C2801"), steel plate (model number "SS400"), and stainless steel plate (model number "SUS304") - were thoroughly polished with sandpaper (grit: #400) and then degreased using ultrasonic cleaning in hexane. The test pieces and metal plates were then alternately stacked and sandwiched in a tightly packed position.

[0091] Fig. 1 is an explanatory diagram of a corrosion and stickiness test according to an embodiment of the present invention. As shown in Fig. 1, a first test piece 100-1 to a fourth test piece 100-4 of a rubber metal laminate were used in the corrosion and stickiness test. The first test piece 100-1 to the fourth test piece 100-4 each comprise stainless steel plates 101-1 to 101-4, first rubber layers 101a-1 to 104a-1 provided on one main surface of the stainless steel plates 101-1 to 101-4, and second rubber layers 101b-1 to 104b-1 provided on the other main surface of the stainless steel plates 101-1 to 101-4, respectively. For the corrosion and stickiness tests, a test specimen 10 was used in which a brass plate 201 was laminated on the first rubber layer 102a-1 of the first test piece 100-1, a second rubber layer 102b-2 of the second test piece 100-2 was laminated on the brass plate 201, a steel plate 202 was laminated on the first rubber layer 102a-2 of the second test piece 100-2, a second rubber layer 102b-3 of the third test piece 100-3 was laminated on the steel plate 202, a stainless steel plate 203 was laminated on the first rubber layer 102a-3 of the third test piece 100-3, and a second rubber layer 102b-4 of the fourth test piece 100-4 was laminated on the stainless steel plate 203. After the specimen 10 was placed in a thermostatic chamber maintained at 70°C for 24 hours, the corrosion and adhesion states of the brass plate 201, the steel plate 202, and the stainless steel plate 203 were visually inspected and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1 below. <Corrosion evaluation criteria> ○: No corrosion on the metal plate ×: There is corrosion on the metal plate <Evaluation criteria for stickiness> ○: No transfer (stickiness) to metal plate ×: Transfer to metal plate (stickiness)

[0092] Example 2 A rubber metal laminate was produced in the same manner as in Example 1, except that 9 parts by mass of a thermal expansion type foaming agent (microcapsules: trade name "Advancell (registered trademark) EM304", manufactured by Sekisui Chemical Co., Ltd.) was used instead of the thermal decomposition type foaming agent, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0093] Example 3 A rubber metal laminate was produced in the same manner as in Example 2, except that the blending amount of the thermal expansion type foaming agent was 16 parts by mass, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0094] Example 4 Furthermore, a rubber metal laminate was produced in the same manner as in Example 3, except that 54 parts by mass of carbon black B (Semi-Reinforcing Furnace (SRF) carbon black: trade name "HTC#SS", manufactured by Nippon Steel Carbon Corporation) was used, and the amount of thermal expansion foaming agent was 20 parts by mass, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0095] Example 5 A rubber metal laminate was produced in the same manner as in Example 4, except that the blending amount of the thermal expansion type foaming agent was 30 parts by mass, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0096] Example 6 A rubber metal laminate was produced in the same manner as in Example 5, except that the amount of amine-based crosslinking agent was 5 parts by mass, the amount of amine-based crosslinking accelerator was 2 parts by mass, and the amount of thermally expandable foaming agent was 35 parts by mass, and foaming characteristics, heat resistance, and corrosion resistance were evaluated. The evaluation results are shown in Table 1 below.

[0097] Example 7 A rubber metal laminate was produced in the same manner as in Example 6, except that the blending amount of the thermal expansion type foaming agent was set to 20 parts by mass, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0098] (Comparative Example 1) Instead of ethylene acrylate rubber, we have developed nitrile rubber (high nitrile: bound acrylonitrile content 41.5%: product name "JSR The following were used: 100 parts by mass of "N220S" manufactured by JSR Corporation; 5 parts by mass of zinc oxide (manufactured by Seido Chemical Co., Ltd.); 8 parts by mass of a plasticizer (non-phthalate plasticizer: trade name "Mezamol" manufactured by Lanxess AG); 1.2 parts by mass of a sulfur-based crosslinking agent (trade name "Colloidal Sulfur A" manufactured by Tsurumi Chemical Co., Ltd.) was used instead of the amine-based crosslinking agent; 0.6 parts by mass of sulfur-based crosslinking accelerator A (dibenzothiazyl disulfide: trade name "Noccela DM-10" manufactured by Ouchi Shinko Chemical Co., Ltd.) and 2.2 parts by mass of sulfur-based crosslinking accelerator B (tetramethylthiuram disulfide: trade name "Accel TS-10" manufactured by Ouchi Shinko Chemical Co., Ltd.) were used instead of the amine-based accelerator; and a thermal expansion type blowing agent (microcapsules: trade name "Advancell (registered trademark)" was used instead of the thermal decomposition type blowing agent. A rubber metal laminate was produced in the same manner as in Example 1, except that 12 parts by mass of "EM304" (manufactured by Sekisui Chemical Co., Ltd.) was used, and foaming characteristics, heat resistance, and corrosion resistance were evaluated. The evaluation results are shown in Table 1 below.

[0099] (Comparative Example 2) A rubber metal laminate was produced in the same manner as in Comparative Example 1, except that 8 parts by mass of a quinoid crosslinking agent (p-quinone dioxime, trade name "Valnoc GM-P", manufactured by Ouchi Shinko Chemical Co., Ltd.) was used instead of the sulfur crosslinking agent, and 3 parts by mass of a crosslinking aid (m-phenylenedimaleimide, trade name "Valnoc PM", manufactured by Ouchi Shinko Chemical Co., Ltd.) was used instead of crosslinking accelerators A and B, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0100] (Comparative Example 3) A rubber metal laminate was produced in the same manner as in Comparative Example 2, except that 2 parts by mass of a peroxide-based crosslinking agent (dicumyl peroxide: trade name "Percumyl D", manufactured by NOF Corporation) was used instead of the sulfur-based crosslinking agent, and no crosslinking aid was used, and foaming property evaluation, heat resistance evaluation, and corrosion resistance evaluation were carried out. The evaluation results are shown in Table 1 below.

[0101] [Table 1]

[0102] The amounts of each component in Table 1 above are as follows: Ethylene acrylate rubber: Product name "VAMAC GLS" (manufactured by DuPont) Nitrile rubber: High nitrile rubber (bound acrylonitrile content 41.5%): Product name "JSR N220S" (manufactured by JSR Corporation) Carbon black A: Medium thermal (MT) carbon black: Trade name "THERMAX N990 LSR" (manufactured by Cancarb) Carbon black B: Medium reinforcing (SRF: Semi-Reinforcing Furnace) carbon black: Product name "HTC♯SS" (manufactured by Nippon Steel Carbon Co., Ltd.) Amine crosslinker: hexamethylenediamine carbamate: trade name "ChemiNox AC6-66" (manufactured by Unimatec Co., Ltd.) Amine-based crosslinking accelerator: Aminated derivative (tertiary amine complex adsorbed on an amorphous silica support): Trade name "Vulcofac ACT-55" (manufactured by DuPont) Sulfur-based crosslinking agent: Colloidal sulfur A (Tsurumi Chemical Co., Ltd.) Sulfur-based crosslinking accelerator A: Dibenzothiazyl disulfide: Product name "Noccela DM-10" (manufactured by Ouchi Shinko Chemical Co., Ltd.) Sulfur-based crosslinking accelerator B: Tetramethylthiuram disulfide: Trade name "Accel TS-10" (manufactured by Ouchi Shinko Chemical Co., Ltd.) Quinoid crosslinking agent: p-quinonedioxime: trade name "Valnoc GM-P" (manufactured by Ouchi Shinko Chemical Co., Ltd.) Crosslinking aid: m-phenylenedimaleimide: trade name "Balnoc PM" (manufactured by Ouchi Shinko Chemical Co., Ltd.) Peroxide-based crosslinking agent: Dicumyl peroxide: Trade name "Percumyl D" (manufactured by NOF Corporation) Stearic acid: Trade name "DTST" (Miyoshi Oil Co., Ltd.) Antioxidant: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine: trade name "Nocrac CD" (manufactured by Lanxess) Zinc oxide (Seido Chemical Co., Ltd.) Plasticizer: Non-phthalate plasticizer: Trade name "Mezamol" (manufactured by Lanxess) Thermal decomposition type foaming agent: Azodicarbonamide: Product name "Vinihole AC#3" (manufactured by Eiwa Kasei Co., Ltd.) Thermal expansion foaming agent: Microcapsules: Product name "Advancell EM304" (manufactured by Sekisui Chemical Co., Ltd.)

[0103] As can be seen from Table 1, rubber metal laminates in which the rubber layer contains ethylene acrylate rubber and an amine-based crosslinking agent not only achieve a sufficient foaming ratio for the rubber layer, but also have excellent heat resistance, corrosion resistance, and stickiness (see Examples 1 to 7). Furthermore, comparing Example 1 with Examples 2 to 7, it can be seen that stable foaming characteristics are obtained regardless of whether a thermally expandable foaming agent or a thermally decomposable foaming agent is used as the foaming agent, and excellent heat resistance, corrosion resistance, and stickiness are obtained. Furthermore, as can be seen from Examples 1 to 7, excellent heat resistance, corrosion resistance, and stickiness can be obtained even when the blending amounts of foaming agent, carbon black, and amine-based crosslinking agent are changed.

[0104] In contrast, when nitrile rubber was crosslinked with a sulfur-based crosslinking agent, the brass plate corroded in the corrosion and tack tests, resulting in poor corrosion resistance (see Comparative Example 1). This result is believed to be due to the corrosion of the brass plate caused by the sulfur component from the sulfur-based crosslinking agent contained in the rubber layer. Furthermore, when nitrile rubber was crosslinked with a peroxide-based crosslinking agent, no corrosion occurred in the corrosion and tack tests, but the rubber stuck to the steel plate and stainless steel plate, resulting in partial transfer, resulting in poor tack (see Comparative Example 3). This result is believed to be due to the fact that the peroxide-based crosslinking agent reacted with oxygen in the air, preventing sufficient crosslinking in the air. Furthermore, in Comparative Examples 1 and 2, the pencil hardness changed significantly before and after the heat resistance test, resulting in poor heat resistance. This result is believed to be due to the use of nitrile rubber, which did not provide sufficient heat resistance. Furthermore, when nitrile rubber was crosslinked with a quinoid-based crosslinking agent, the corrosion resistance and tack resistance were good, but the pencil hardness changed significantly before and after the heat resistance test, resulting in poor heat resistance, similar to Comparative Examples 1 and 3 (see Comparative Example 2).

[0105] From the above results, it can be seen that, according to the above embodiment, by crosslinking ethylene acrylate rubber with an amine-based crosslinking agent, it is possible to realize a rubber composition that not only achieves a sufficient expansion ratio but also produces a rubber-metal laminate that has good corrosion resistance and stickiness as well as excellent heat resistance, a rubber-metal laminate using the rubber composition, and a gasket equipped with the rubber-metal laminate. [Industrial Applicability]

[0106] As explained above, according to the above-described embodiments, it is possible to prevent metal corrosion due to sulfur components, and further, it is possible to realize a rubber composition, a rubber-metal laminate, and a method for manufacturing a gasket and a rubber-metal laminate that can provide a gasket with excellent heat resistance. In particular, the present invention can be used for gaskets in general, such as gaskets for inverter cases for electric vehicles (EVs) and hybrid electric vehicles (HEVs), and heat-resistant gaskets.

[0107] Although one embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the content of this embodiment. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiment.

Claims

1. 100 parts by mass of ethylene acrylate rubber, which is a terpolymer of ethylene, an acrylic acid ester, and a carboxyl group-containing unsaturated compound; 1 part by mass or more and 25 parts by mass or less of pyrolytic carbon black; 0.1 parts by mass or more and 20 parts by mass or less of an amine-based crosslinking agent; a foaming agent in an amount of 1 part by mass or more and 50 parts by mass or less; Contains A rubber composition (excluding those containing a dialkyl secondary amine), characterized in that the foaming agent is a thermal expansion foaming agent.

2. The rubber composition according to claim 1 , wherein the amine-based crosslinking agent includes a diamine.

3. The rubber composition according to claim 1 or 2, wherein the foaming agent includes thermally expandable microcapsules.

4. A metal member; a foamed rubber layer provided on the metal member and formed by crosslinking the rubber composition according to any one of claims 1 to 3; A rubber metal laminate comprising:

5. 5. The rubber metal laminate according to claim 4, which does not cause corrosion on brass plates, steel plates, or stainless steel plates in a corrosion and stickiness test in accordance with JIS B2403 Section 9.

2.

6. 6. The rubber metal laminate according to claim 4, wherein the change in pencil hardness of the foamed rubber layer in a scratch hardness test in accordance with JIS K5600-5-4 before and after heat aging at 150°C for 24 hours is 3 points or less.

7. A gasket comprising the rubber metal laminate according to any one of claims 4 to 6.

8. a rubber composition preparation step of obtaining a rubber composition (excluding those containing dialkyl secondary amines) by mixing 100 parts by mass of ethylene acrylate rubber, which is a terpolymer of ethylene, an acrylic acid ester, and a carboxyl group-containing unsaturated compound, 1 part by mass or more and 25 parts by mass or less of pyrolytic carbon black, 0.1 part by mass or more and 20 parts by mass or less of an amine-based crosslinking agent, and 1 part by mass or more and 50 parts by mass or less of a foaming agent; a crosslinking step of applying the rubber composition onto a metal member and crosslinking the composition by oven crosslinking to obtain a rubber-metal laminate; Including, A method for manufacturing a rubber metal laminate, wherein the foaming agent is a thermal expansion type foaming agent.

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