Crosslinkable acrylic rubber composition and crosslinked rubber

Abstract

To provide a crosslinkable acryl rubber composition that can give a crosslinked rubber having excellent extrusion scorch stability and heat resistance.SOLUTION: A crosslinkable acryl rubber composition comprises an acryl rubber, an aromatic polyvalent primary amine compound and an aliphatic monovalent secondary amine compound, the aliphatic monovalent secondary amine compound being a dicycloalkyl amine compound or a dicycloalkyl amine compound salt of ethylene glycol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cross-linkable acrylic rubber composition that can give a cross-linked rubber product that has excellent extrusion scorch stability and heat resistance, and to a cross-linked rubber product obtained using such a cross-linkable acrylic rubber composition. [Background technology]

[0002] With the development of petrochemistry, polymers made up of organic compounds have contributed to the development of humanity in various forms such as plastics, rubber, fibers, and films. Because these are used in a variety of environments depending on their purpose, they have been improved to ensure long-term use by endowing them with durability in the expected environments. For example, products have been developed that are UV-resistant for plastics used outdoors, and cold-resistant for rubber that functions in extremely cold regions.

[0003] Meanwhile, the use of internal combustion engines, such as engines, has increased with industrial development. Because they require lubricating oil and generate a great deal of heat, the polymers used in them must be resistant to oil and high temperatures. Polymers used in automobile engines, in particular, must maintain flexibility for long periods of time even when exposed to oil and high temperatures, and must not develop cracks or other defects. To meet these requirements, various oil- and heat-resistant rubbers have been developed. Among these, acrylic rubber, a polymer with excellent elasticity, oil resistance, heat resistance, and flexibility, is widely used in automobile engine seals, gaskets, packings, hoses, and other components. Its oil and heat resistance are further enhanced by modifying crosslinking structures, antioxidants, and compounding agents to meet specific requirements.

[0004] For example, Patent Document 1 discloses a vulcanizable acrylic rubber composition containing 0.05 to 5 parts by weight of a polyvalent primary amine vulcanizing agent (B) and 0.5 to 5.5 parts by weight of an aliphatic monovalent secondary amine compound (C-1) and / or an aliphatic monovalent tertiary amine compound (C-2) per 100 parts by weight of acrylic rubber (A) in which the total amount of acrylic acid ester monomer (a) units and carboxyl group-containing ethylenically unsaturated monomer (b) units is 80% by weight or more of the monomer units, and the acrylic acid ester monomer (a) units account for 90 to 99.9% by weight of the total amount. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-063584 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology of Patent Document 1 provides a vulcanizable acrylic rubber composition that is excellent in kneading properties, is less likely to scorch during vulcanization, and the resulting vulcanizate has excellent metal corrosion resistance and oil resistance, but there is room for improvement in heat resistance under severe temperature environments (for example, environments of 190°C or higher). Also, there has been a need for a technology that can achieve both excellent scorch stability and excellent heat resistance in the resulting cross-linked rubber product.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a cross-linkable acrylic rubber composition that can give a cross-linked rubber product that is excellent in extrusion scorch stability and heat resistance (for example, heat resistance in an environment of 190°C or higher). Another object of the present invention is to provide a cross-linked rubber product obtained by using such a cross-linkable acrylic rubber composition. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to achieve the above object, they have found that by using an aromatic polyvalent primary amine compound and a specific aliphatic monovalent secondary amine compound in combination, a cross-linkable acrylic rubber composition can give a cross-linked rubber product that is excellent in extrusion scorch stability and heat resistance, and have thus completed the present invention.

[0009] That is, according to the present invention, there is provided a crosslinkable acrylic rubber composition containing an acrylic rubber, an aromatic polyvalent primary amine compound, and an aliphatic monovalent secondary amine compound, wherein the aliphatic monovalent secondary amine compound is a dicycloalkylamine compound or a dicycloalkylamine compound salt of ethylene glycol.

[0010] The crosslinkable acrylic rubber composition of the present invention preferably further contains a diphenylamine compound, and the diphenylamine compound is preferably styrenated diphenylamine, and the diphenylamine compound is preferably styrenated diphenylamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. The crosslinkable acrylic rubber composition of the present invention is preferably used for forming hydraulic hoses, air hoses, turbo hoses, or tubes.

[0011] Furthermore, according to the present invention, there is provided a cross-linked rubber product obtained by cross-linking the above cross-linkable acrylic rubber composition. [Effects of the Invention]

[0012] It is possible to provide a cross-linkable acrylic rubber composition that can give a cross-linked rubber product that has excellent extrusion scorch stability and heat resistance (for example, heat resistance in an environment of 190°C or higher), and a cross-linked rubber product obtained using such a cross-linkable acrylic rubber composition. DETAILED DESCRIPTION OF THE INVENTION

[0013] The crosslinkable acrylic rubber composition of the present invention contains an acrylic rubber, an aromatic polyvalent primary amine compound, and an aliphatic monovalent secondary amine compound.

[0014] <Crosslinkable acrylic rubber composition> The acrylic rubber used in the present invention is not particularly limited as long as it contains (meth)acrylic acid ester monomer units (meaning acrylic acid ester monomers and / or methacrylic acid ester monomers; hereinafter, the same applies to methyl (meth)acrylate, etc.) as the main component in the molecule (for example, 50% by weight or more of all monomer units in the acrylic rubber).

[0015] The (meth)acrylic acid ester monomer forming the (meth)acrylic acid ester monomer unit as the main component of the acrylic rubber used in the present invention is not particularly limited, but examples thereof include (meth)acrylic acid alkyl ester monomers and (meth)acrylic acid alkoxyalkyl ester monomers.

[0016] The (meth)acrylic acid alkyl ester monomer is not particularly limited, but is preferably an ester of an alkanol having 1 to 8 carbon atoms with (meth)acrylic acid. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. Among these, ethyl (meth)acrylate and n-butyl (meth)acrylate are preferred, with ethyl acrylate and n-butyl (meth)acrylate being particularly preferred. These can be used alone or in combination of two or more.

[0017] The (meth)acrylic acid alkoxyalkyl ester monomer is not particularly limited, but is preferably an ester of an alkoxyalkyl alcohol having 2 to 12 carbon atoms with (meth)acrylic acid, and more preferably an ester of an alkoxyalkyl alcohol having 2 to 8 carbon atoms with (meth)acrylic acid. Specific examples include methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. Among these, 2-ethoxyethyl (meth)acrylate and 2-methoxyethyl (meth)acrylate are preferred, with 2-ethoxyethyl acrylate and 2-methoxyethyl acrylate being particularly preferred. These may be used alone or in combination of two or more.

[0018] The content of (meth)acrylic acid ester monomer units in the acrylic rubber used in the present invention is 50 to 100% by weight, preferably 50 to 99.9% by weight, more preferably 60 to 99.5% by weight, even more preferably 70 to 99.5% by weight, and particularly preferably 70 to 99% by weight. By keeping the content of (meth)acrylic acid ester monomer units within the above range, the weather resistance, heat resistance, and oil resistance of the obtained cross-linked rubber can be improved.

[0019] In the present invention, the (meth)acrylic acid ester monomer units preferably consist of 30 to 100% by weight of (meth)acrylic acid alkyl ester monomer units and 70 to 0% by weight of (meth)acrylic acid alkoxyalkyl ester monomer units.

[0020] The acrylic rubber used in the present invention may contain crosslinkable monomer units in addition to (meth)acrylic acid ester monomer units.

[0021] The crosslinkable monomer that forms the crosslinkable monomer unit is not particularly limited, but examples thereof include carboxyl group-containing monomers, monomers having epoxy groups, monomers having halogen atoms, diene monomers, etc. These crosslinkable monomers can be used alone or in combination of two or more.

[0022] The carboxyl group-containing monomer is not particularly limited, but examples thereof include α,β-ethylenically unsaturated monocarboxylic acids having 3 to 12 carbon atoms, α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms, and monoesters of α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms and alkanols having 1 to 8 carbon atoms.

[0023] Specific examples of the α,β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms include acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, and cinnamic acid. Specific examples of the α,β-ethylenically unsaturated dicarboxylic acid having 4 to 12 carbon atoms include butenedioic acids such as fumaric acid and maleic acid; itaconic acid; citraconic acid; chloromaleic acid; and the like. Specific examples of monoesters of α,β-ethylenically unsaturated dicarboxylic acids having 4 to 12 carbon atoms and alkanols having 1 to 8 carbon atoms include butenedioic acid mono-chain alkyl esters such as monomethyl fumarate, monoethyl fumarate, mono-n-butyl fumarate, monomethyl maleate, monoethyl maleate, and mono-n-butyl maleate; butenedioic acid monoesters having an alicyclic structure such as monocyclopentyl fumarate, monocyclohexyl fumarate, monocyclohexenyl fumarate, monocyclopentyl maleate, monocyclohexyl maleate, and monocyclohexenyl maleate; and itaconic acid monoesters such as monomethyl itaconate, monoethyl itaconate, mono-n-butyl itaconate, and monocyclohexyl itaconate. Among these, butenedioic acid mono-chain alkyl esters or butenedioic acid monoesters having an alicyclic structure are preferred, mono-n-butyl fumarate, mono-n-butyl maleate, monocyclohexyl fumarate, and monocyclohexyl maleate are more preferred, and mono-n-butyl fumarate and monocyclohexyl maleate are even more preferred. These carboxyl group-containing monomers can be used alone or in combination of two or more. Note that among the above monomers, dicarboxylic acids also include those that exist as anhydrides.

[0024] In the present invention, when a carboxyl group-containing monomer is used as the cross-linkable monomer, the acrylic rubber can be a carboxyl group-containing acrylic rubber. When the acrylic rubber is a carboxyl group-containing acrylic rubber, the heat resistance of the resulting acrylic rubber cross-linked product can be further improved.

[0025] When the acrylic rubber used in the present invention is a carboxyl group-containing acrylic rubber, the content of the carboxyl group-containing monomer units is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, and even more preferably 1 to 5% by weight. By having the content of the carboxyl group-containing monomer units in the above range, it is possible to obtain a better balance between the strength and elongation of the obtained cross-linked rubber product. In particular, by making the content of the carboxyl group-containing monomer units equal to or greater than the above lower limit, cross-linking can be carried out sufficiently, making it easier to maintain the shape of the obtained cross-linked rubber product. On the other hand, by making the content of the carboxyl group-containing monomer units equal to or less than the above upper limit, it is possible to increase the elongation of the obtained cross-linked rubber product and decrease the compression set rate.

[0026] In addition, when the acrylic rubber used in the present invention is a carboxyl group-containing acrylic rubber, the content of the carboxyl groups, i.e., the number of moles (ephr) of the carboxyl groups per 100 g of the acrylic rubber, is preferably 4×10 -4 ~4×10 -1 (ephr), more preferably 1 × 10 -3 ~2×10-1 (ephr), more preferably 5 × 10 -3 ~1×10 -1 (ephr). By making the carboxyl group content equal to or greater than the above lower limit, crosslinking can be carried out sufficiently, the mechanical properties of the obtained cross-linked rubber product can be improved, and the surface texture of the molded article can be made smooth. On the other hand, by making the carboxyl group content equal to or less than the above upper limit, the elongation of the obtained cross-linked rubber product can be increased and the compression set can be reduced.

[0027] The monomer having an epoxy group is not particularly limited, but examples thereof include epoxy group-containing (meth)acrylic acid esters and epoxy group-containing ethers.

[0028] A specific example of the epoxy group-containing (meth)acrylic acid ester is glycidyl (meth)acrylate. Specific examples of epoxy group-containing ethers include allyl glycidyl ether and vinyl glycidyl ether. Among these, glycidyl methacrylate and allyl glycidyl ether are preferred. These epoxy group-containing monomers can be used alone or in combination of two or more.

[0029] In the present invention, when a monomer having an epoxy group is used as the crosslinkable monomer, the acrylic rubber can be an epoxy group-containing acrylic rubber.

[0030] When the acrylic rubber used in the present invention is an epoxy group-containing acrylic rubber, the content of the epoxy group-containing monomer unit is preferably 0.1 to 10 wt%, more preferably 0.5 to 7 wt%, and even more preferably 0.5 to 5 wt%. By having the content of the epoxy group-containing monomer unit in the above range, the balance between strength and elongation of the obtained cross-linked rubber product can be made better. In particular, by setting the content of the epoxy group-containing monomer unit to be equal to or greater than the above lower limit, cross-linking can be carried out sufficiently, making it easier to maintain the shape of the obtained cross-linked rubber product. On the other hand, by setting the content of the epoxy group-containing monomer unit to be equal to or less than the above upper limit, the elongation of the obtained cross-linked rubber product can be increased and the compression set can be reduced.

[0031] The monomer having a halogen atom is not particularly limited, but examples thereof include unsaturated alcohol esters of halogen-containing saturated carboxylic acids, (meth)acrylic acid haloalkyl esters, (meth)acrylic acid haloacyloxyalkyl esters, (meth)acrylic acid (haloacetylcarbamoyloxy)alkyl esters, halogen-containing unsaturated ethers, halogen-containing unsaturated ketones, halomethyl group-containing aromatic vinyl compounds, halogen-containing unsaturated amides, and haloacetyl group-containing unsaturated monomers.

[0032] Specific examples of unsaturated alcohol esters of halogen-containing saturated carboxylic acids include vinyl chloroacetate, vinyl 2-chloropropionate, and allyl chloroacetate. Specific examples of (meth)acrylic acid haloalkyl esters include chloromethyl (meth)acrylate, 1-chloroethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 1,2-dichloroethyl (meth)acrylate, 2-chloropropyl (meth)acrylate, 3-chloropropyl (meth)acrylate, and 2,3-dichloropropyl (meth)acrylate. Specific examples of (meth)acrylic acid haloacyloxyalkyl esters include 2-(chloroacetoxy)ethyl (meth)acrylate, 2-(chloroacetoxy)propyl (meth)acrylate, 3-(chloroacetoxy)propyl (meth)acrylate, and 3-(hydroxychloroacetoxy)propyl (meth)acrylate. Specific examples of (meth)acrylic acid (haloacetylcarbamoyloxy)alkyl esters include 2-(chloroacetylcarbamoyloxy)ethyl (meth)acrylate and 3-(chloroacetylcarbamoyloxy)propyl (meth)acrylate. Specific examples of halogen-containing unsaturated ethers include chloromethyl vinyl ether, 2-chloroethyl vinyl ether, 3-chloropropyl vinyl ether, 2-chloroethyl allyl ether, and 3-chloropropyl allyl ether. Specific examples of halogen-containing unsaturated ketones include 2-chloroethyl vinyl ketone, 3-chloropropyl vinyl ketone, and 2-chloroethyl allyl ketone. Specific examples of halomethyl group-containing aromatic vinyl compounds include p-chloromethylstyrene, m-chloromethylstyrene, o-chloromethylstyrene, and p-chloromethyl-α-methylstyrene. Specific examples of halogen-containing unsaturated amides include N-chloromethyl(meth)acrylamide. Specific examples of haloacetyl group-containing unsaturated monomers include 3-(hydroxychloroacetoxy)propyl allyl ether and p-vinylbenzyl chloroacetic acid ester.

[0033] Among these, unsaturated alcohol esters of halogen-containing saturated carboxylic acids and halogen-containing unsaturated ethers are preferred, vinyl chloroacetate and 2-chloroethyl vinyl ether are more preferred, and vinyl chloroacetate is even more preferred. These halogen-containing monomers can be used alone or in combination of two or more.

[0034] In the present invention, when a monomer having a halogen atom is used as the crosslinkable monomer, the acrylic rubber can be a halogen atom-containing acrylic rubber.

[0035] When the acrylic rubber used in the present invention is a halogen-containing acrylic rubber, the content of the monomer units having halogen atoms is preferably 0.1 to 10% by weight, more preferably 0.5 to 7% by weight, and even more preferably 0.5 to 5% by weight. By having the content of the monomer units having halogen atoms in the above range, the balance between strength and elongation of the obtained cross-linked rubber product can be made even better. In particular, by setting the content of the monomer units having halogen atoms to be equal to or greater than the above lower limit, cross-linking can be carried out sufficiently, making it easier to maintain the shape of the obtained cross-linked rubber product. On the other hand, by setting the content of the monomer units having halogen atoms to be equal to or less than the above upper limit, the elongation of the obtained cross-linked rubber product can be increased and the compression set can be reduced.

[0036] The diene monomer includes a conjugated diene monomer and a non-conjugated diene monomer. Specific examples of the conjugated diene monomer include 1,3-butadiene, isoprene, and piperylene. Specific examples of the non-conjugated diene monomer include ethylidene norbornene, dicyclopentadiene, dicyclopentadienyl (meth)acrylate, and 2-dicyclopentadienylethyl (meth)acrylate.

[0037] The above-mentioned carboxyl group-containing monomers, epoxy group-containing monomers, halogen atom-containing monomers, and diene monomers can be used either individually or in combination of two or more.

[0038] When the acrylic rubber used in the present invention is the above-mentioned carboxyl group-containing acrylic rubber, epoxy group-containing acrylic rubber, halogen atom-containing acrylic rubber, or carboxyl group- and halogen atom-containing acrylic rubber, it may contain other crosslinkable monomer units as necessary. The crosslinkable monomers forming the other crosslinkable monomer units can be used alone or in combination of two or more. The content of the other crosslinkable monomer units in the acrylic rubber used in the present invention is preferably 0 to 9.9 wt%, more preferably 0 to 6.5 wt%, even more preferably 0 to 4.5 wt%, and particularly preferably 0 to 4 wt% (however, the total amount of all crosslinkable monomer units in the acrylic rubber is preferably 0.1 to 10 wt%, more preferably 0.5 to 7 wt%, even more preferably 0.5 to 5 wt%, and particularly preferably 1 to 5 wt%). By keeping the content of these other crosslinkable monomer units below the above-mentioned upper limit, the elongation of the resulting crosslinked rubber can be increased and the compression set can be reduced.

[0039] Furthermore, the acrylic rubber used in the present invention may have, in addition to the (meth)acrylic acid ester monomer units and the crosslinkable monomer units, units of other monomers copolymerizable with the (meth)acrylic acid ester monomer or the crosslinkable monomer, as necessary.

[0040] The other copolymerizable monomers are not particularly limited, but examples thereof include aromatic vinyl monomers, α,β-ethylenically unsaturated nitrile monomers, monomers having two or more acryloyloxy groups (hereinafter sometimes referred to as "polyfunctional acrylic monomers"), olefin-based monomers, and vinyl ether compounds.

[0041] Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, and divinylbenzene. Specific examples of the α,β-ethylenically unsaturated nitrile monomer include acrylonitrile and methacrylonitrile. Specific examples of polyfunctional acrylic monomers include ethylene glycol di(meth)acrylate and propylene glycol di(meth)acrylate. Specific examples of the olefin monomer include ethylene, propylene, 1-butene, and 1-octene. Specific examples of vinyl ether compounds include vinyl acetate, ethyl vinyl ether, and n-butyl vinyl ether.

[0042] Among these, styrene, acrylonitrile, methacrylonitrile, ethylene and vinyl acetate are preferred, and acrylonitrile, methacrylonitrile, ethylene and vinyl acetate are more preferred.

[0043] The other copolymerizable monomers can be used alone or in combination of two or more. The content of units of other monomers in the acrylic rubber is preferably 0 to 50% by weight, more preferably 0 to 49.9% by weight, even more preferably 0 to 39.5% by weight, and particularly preferably 0 to 29.5% by weight.

[0044] The acrylic rubber used in the present invention can be obtained by polymerizing the above-mentioned monomers. The polymerization reaction can be carried out by any of emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization, but emulsion polymerization is preferred from the standpoint of ease of control of the polymerization reaction.

[0045] The emulsion polymerization may be any of a batch system, a semi-batch system, and a continuous system. The polymerization is usually carried out in the temperature range of 0 to 70°C, preferably 5 to 50°C.

[0046] The weight-average molecular weight (Mw) of the acrylic rubber used in the present invention is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 100,000 to 4,000,000, and even more preferably 150,000 to 3,500,000. The weight-average molecular weight of the acrylic rubber can be measured, for example, by gel permeation chromatography as a polystyrene-equivalent value.

[0047] The Mooney viscosity (ML1+4, 100°C) (polymer Mooney) of the acrylic rubber used in the present invention produced in this manner is preferably 10-150, more preferably 10-80, even more preferably 20-70, and particularly preferably 25-60.

[0048] In the present invention, the acrylic rubbers thus produced can be used alone or in combination of two or more.

[0049] <Aromatic polyvalent primary amine compounds> The crosslinkable acrylic rubber composition of the present invention contains an aromatic polyvalent primary amine compound in addition to the above-mentioned acrylic rubber.

[0050] The aromatic polyvalent primary amine compound used in the present invention is an aromatic compound having a plurality of primary amino groups or a salt thereof, and functions as a crosslinking agent in the crosslinkable acrylic rubber composition of the present invention.

[0051] The aromatic polyvalent primary amine compound is not particularly limited as long as it is an aromatic compound having a plurality of primary amino groups or a salt thereof, but is preferably an aromatic divalent primary amine compound, an aromatic trivalent primary amine compound, or a salt thereof, and more preferably an aromatic divalent primary amine compound or a salt thereof.

[0052] Specific examples of aromatic polyvalent primary amine compounds include aromatic divalent primary amine compounds such as 4,4'-methylenedianiline, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 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, and 4,4'-bis(4-aminophenoxy)biphenyl; and N,N',N"- and aromatic trivalent primary amine compounds such as triphenyl-1,3,5-benzenetriamine. Among these, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-(p-phenylenediisopropylidene)dianiline, and 4,4'-(m-phenylenediisopropylidene)dianiline are preferred, with 2,2'-bis[4-(4-aminophenoxy)phenyl]propane being more preferred. In the present invention, the aromatic polyvalent primary amine compounds can be used alone or in combination of two or more.

[0053] The content of the aromatic polyvalent primary amine compound in the crosslinkable acrylic rubber composition of the present invention is not particularly limited, but is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 4 parts by weight, and even more preferably 0.2 to 3 parts by weight, relative to 100 parts by weight of the acrylic rubber. When the content of the aromatic polyvalent primary amine compound is within the above range, it is possible to further improve the extrusion scorch stability and further improve the heat resistance of the obtained cross-linked rubber product.

[0054] <Aliphatic monovalent secondary amine compounds> The crosslinkable acrylic rubber composition of the present invention contains, in addition to the above-mentioned acrylic rubber and aromatic polyvalent primary amine compound, a dicycloalkylamine compound or a dicycloalkylamine compound salt of ethylene glycol as an aliphatic monovalent secondary amine compound.

[0055] The dicycloalkylamine compound or the salt of ethylene glycol of a dicycloalkylamine compound as the aliphatic monovalent secondary amine compound functions as a crosslinking accelerator in the crosslinkable acrylic rubber composition of the present invention.

[0056] Examples of dicycloalkylamine compounds include dicyclopentylamine, dicyclohexylamine, and dicycloheptylamine, with dicyclohexylamine being preferred. The same dicycloalkylamine compounds that form dicycloalkylamine compound salts of ethylene glycol include similar compounds, with dicyclohexylamine being preferred. In the present invention, the aliphatic monovalent secondary amine compounds can be used alone or in combination of two or more. The dicycloalkylamine compound or the dicycloalkylamine compound salt of ethylene glycol may be mixed with an alcohol such as an alkyl alcohol, and may further contain an inorganic acid and / or an organic acid. The dicycloalkylamine compound salt of ethylene glycol may be a mixture of ethylene glycol and a dicycloalkylamine compound, or may be a salt formed between ethylene glycol and a dicycloalkylamine compound and an inorganic acid and / or an organic acid.

[0057] The content of the aliphatic monovalent secondary amine compound in the crosslinkable acrylic rubber composition of the present invention is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 7.5 parts by weight, and even more preferably 1 to 5 parts by weight, relative to 100 parts by weight of the acrylic rubber. When the content of the aliphatic monovalent secondary amine compound is within the above range, it is possible to further improve the extrusion scorch stability and further improve the heat resistance of the obtained cross-linked rubber product.

[0058] <Other ingredients> The crosslinkable acrylic rubber composition of the present invention may contain other components in addition to the above-mentioned components.

[0059] The cross-linkable acrylic rubber composition of the present invention preferably contains a diphenylamine compound. By containing a diphenylamine compound, the heat resistance of the obtained cross-linked rubber product can be further improved.

[0060] Diphenylamine compounds include diphenylamine, compounds in which hydrogen atoms in diphenylamine are substituted with any substituent, and salts thereof. Examples of diphenylamine compounds include styrenated diphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, p-(p-toluenesulfonylamido)-diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N-diphenyl-p-phenylenediamine, and N-isopropyl-N'-phenyl-p-phenylenediamine. Among these, styrenated diphenylamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine are preferred, with styrenated diphenylamine being more preferred. Another preferred embodiment of the diphenylamine compound is the combined use of styrenated diphenylamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. In the present invention, the diphenylamine compounds can be used alone or in combination.

[0061] The content of the diphenylamine compound in the crosslinkable acrylic rubber composition of the present invention (when two or more diphenylamine compounds are used, the total amount) is not particularly limited, but is preferably 0.01 to 15 parts by weight, more preferably 0.05 to 10 parts by weight, and even more preferably 0.1 to 5 parts by weight, relative to 100 parts by weight of the acrylic rubber. When the content of the diphenylamine compound is within the above range, the heat resistance of the obtained cross-linked rubber can be further improved.

[0062] The crosslinkable acrylic rubber composition of the present invention may contain a filler. The filler is not particularly limited, but examples thereof include reinforcing fillers and non-reinforcing fillers, and among these, reinforcing fillers are preferred.

[0063] Examples of reinforcing fillers include carbon blacks such as furnace black, acetylene black, thermal black, channel black, and graphite; silicas such as wet silica, dry silica, and colloidal silica; and examples of non-reinforcing fillers include quartz powder, clays such as diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, aluminum sulfate, calcium sulfate, and barium sulfate.

[0064] These fillers can be used alone or in combination of two or more. The content of the filler in the crosslinkable acrylic rubber composition of the present invention is not particularly limited, but is preferably 1 to 200 parts by weight, more preferably 10 to 150 parts by weight, and even more preferably 20 to 100 parts by weight, per 100 parts by weight of the acrylic rubber.

[0065] In addition to the above-mentioned components, the crosslinkable acrylic rubber composition of the present invention can also contain compounding agents commonly used in the field of rubber processing. Examples of such compounding agents include antioxidants, light stabilizers, plasticizers, processing aids, slip agents, adhesives, lubricants, flame retardants, mildew inhibitors, antistatic agents, colorants, silane coupling agents, and crosslinking retarders. The amounts of these compounding agents to be added are not particularly limited as long as they do not impair the purpose and effects of the present invention, and can be appropriately added in amounts depending on the purpose of addition.

[0066] <Method for preparing crosslinkable acrylic rubber composition> The method for preparing the crosslinkable acrylic rubber composition of the present invention is not particularly limited, but a method in which an acrylic rubber, an aromatic polyvalent primary amine compound, and an aliphatic monovalent secondary amine compound are mixed together with various compounding ingredients that are added as necessary is preferred.

[0067] The mixing method is not particularly limited, and examples thereof include a method of kneading using a kneading machine such as a roll, an intermix, a kneader, a Banbury mixer, a screw mixer, etc. The mixing may also be carried out in a solvent.

[0068] Alternatively, the components excluding the aromatic polyvalent primary amine compound, the aliphatic monovalent secondary amine compound, and thermally unstable components may be kneaded in a mixer such as a Banbury mixer, a Brabender mixer, an intermixer, or a kneader, and then transferred to a roll or the like, where the aromatic polyvalent primary amine compound, the aliphatic monovalent secondary amine compound, and the like are added and subjected to secondary kneading to prepare the composition.

[0069] The cross-linkable acrylic rubber composition of the present invention can be obtained in the manner described above. The cross-linkable acrylic rubber composition of the present invention is formulated by combining an aromatic polyvalent primary amine compound with a dicycloalkylamine compound or a dicycloalkylamine compound salt of ethylene glycol as an aliphatic monovalent secondary amine compound, and therefore can provide a cross-linked rubber product that has excellent extrusion scorch stability and heat resistance (for example, heat resistance in an environment of 190°C or higher).

[0070] <Rubber cross-linked products> A cross-linked rubber product can be obtained by cross-linking the cross-linkable acrylic rubber composition of the present invention.

[0071] A cross-linked rubber product is produced by molding and cross-linking a cross-linkable acrylic rubber composition. The molding and cross-linking methods for the cross-linkable acrylic rubber composition are not particularly limited, but examples include a method in which the cross-linkable acrylic rubber composition is extruded using a single-screw or multi-screw extruder to form a molded product, and then heated to cross-link; a method in which the composition is molded using a mold with an injection molding machine, extrusion blow molding machine, transfer molding machine, press molding machine, or the like, and cross-linked by heating during molding at the same time; and the like. Among these methods, a method using an extruder or an injection molding machine is preferred, and a method using an extruder is particularly preferred. Whether molding and cross-linking are performed simultaneously, or whether cross-linking is performed after molding, is not particularly limited, and may be selected depending on the molding method, vulcanization method, size of the molded product, etc.

[0072] The molding temperature when molding and crosslinking the crosslinkable acrylic rubber composition is preferably 15 to 220°C, more preferably 20 to 200°C. The crosslinking temperature is preferably 100°C or higher, more preferably 120 to 250°C. The crosslinking time may be selected arbitrarily within the range of 1 minute to 5 hours. The heating method may be appropriately selected from methods commonly used for crosslinking rubber, such as electric heating, steam heating, oven heating, UHF (ultra-high frequency) heating, and hot air heating.

[0073] Depending on the shape, size, etc. of the cross-linked rubber product, even if the surface is cross-linked, the interior may not be sufficiently cross-linked, so secondary cross-linking may be carried out by further heating. The heating temperature during secondary cross-linking is preferably 100 to 220°C, more preferably 130 to 210°C, and the heating time is preferably 30 minutes to 10 hours, more preferably 1 to 5 hours.

[0074] The cross-linked rubber products thus obtained are suitably used as sealing materials such as O-rings, packings, diaphragms, oil seals, shaft seals, bearing sheaths, mechanical seals, wellhead seals, seals for electrical and electronic equipment, and seals for air compressors; various gaskets such as cylinder head gaskets attached to the joint between a cylinder block and a cylinder head, rocker cover gaskets attached to the joint between a rocker cover and a cylinder head, oil pan gaskets attached to the joint between an oil pan and a cylinder head or a transmission case, gaskets for fuel cell separators attached between a pair of housings sandwiching a unit cell having a positive electrode, an electrolyte plate, and a negative electrode, and gaskets for the top covers of hard disk drives; cushioning materials, vibration-proofing materials; wire coating materials; industrial belts; tubes and hoses; sheets; and the like.

[0075] Furthermore, the cross-linked rubber product of the present invention can be used as an extrusion molded product and a cross-linked product for automobile applications, for example, The present invention is suitable for use in various hoses, including fuel oil hoses for fuel tanks such as fuel hoses, filler neck hoses, vent hoses, vapor hoses, and oil hoses; air hoses such as turbo air hoses and mission control hoses; radiator hoses, heater hoses, brake hoses, and air conditioner hoses.

[0076] The cross-linked rubber product thus obtained is obtained using the cross-linkable acrylic rubber composition of the present invention described above, and therefore has excellent heat resistance even under severe temperature environments (for example, environments of 190°C or higher). Therefore, the cross-linked rubber product thus obtained can be suitably used particularly as hydraulic hoses, air hoses, turbo hoses, and tubes. [Example]

[0077] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In addition, the "parts" below are based on weight unless otherwise specified. Various physical properties were measured as follows.

[0078] <Mooney viscosity> The acrylic rubber composition was subjected to measurement of Mooney viscosity (compound Mooney, ML1+4, 100°C) in accordance with JIS K6300-1:2013.

[0079] <Normal physical properties (hardness, tensile strength, elongation)> The crosslinkable rubber composition was placed in a mold measuring 15 cm in length, 15 cm in width, and 0.2 cm in depth, and press-molded at 170°C for 20 minutes under a pressure of 10 MPa to obtain a sheet-like crosslinked rubber product. The resulting crosslinked rubber product was then transferred to a gear oven and subjected to secondary crosslinking at 170°C for 4 hours. Test specimens were then punched out of the resulting crosslinked rubber product using a JIS No. 3 dumbbell. The tensile strength and elongation at break of the crosslinked rubber product were measured using the resulting test specimens in accordance with JIS K6251:2017. The hardness of the crosslinked rubber product was also measured using a durometer hardness tester (Type A) in accordance with JIS K6253-3. <Extrusion property (Garvey die extrusion test)> The rubber composition was extruded using a single-screw extruder and a Garvey die, and the edge (the part corresponding to the sharpest edge of the Garvey die) was observed in accordance with ASTM D2230 to evaluate the extrudability. The extrudability was evaluated according to the following criteria. ⊚: During extrusion molding, the rubber composition was continuously extruded from the edge portion of the Garvey die, and when the edge of the extruded product was observed from a direction perpendicular to the extrusion direction, the edge portion of the extruded product was not wavy (the ridge line of the edge of the extruded product was straight). ○: During extrusion molding, the rubber composition was continuously extruded from the edge of the Garvey die, and when the edge of the extruded product was observed from a direction perpendicular to the extrusion direction, the edge of the extruded product was slightly wavy (the ridge line of the edge of the extruded product was a fine wavy line). △: During extrusion molding, the rubber composition was continuously extruded from the edge portion of the Garvey die, and when the edge of the extruded product was observed from a direction perpendicular to the extrusion direction, the edge portion of the extruded product was significantly wavy (the ridge line of the edge of the extruded product was a rough wavy line). ×: During extrusion molding, the rubber composition was discontinuously extruded from the edge portion of the Garvey die, and there were parts in the extrusion molded product where no edge was formed. When the edge of the extrusion molded product was observed from a direction perpendicular to the extrusion direction, the edge portion of the extrusion molded product was excessively wavy (the ridge line of the edge of the extrusion molded product could not be grasped).

[0080] <Extrusion scorch stability (Mooney scorch time t5)> The acrylic rubber composition was subjected to Mooney scorch measurement at 125°C in accordance with JIS K6300, and the Mooney scorch time t5 (minutes) was measured. In this measurement, the time it took for the Mooney viscosity to increase by 5M from the minimum Mooney viscosity value Vmin was defined as the Mooney scorch time t5. It can be determined that the longer the Mooney scorch time t5, the more excellent the extrusion scorch stability.

[0081] <Heat resistance> Test specimens were prepared in the same manner as in the evaluation of normal physical properties. The obtained test specimens were heated at 190°C for 94 hours to obtain test specimens after heating at 190°C. Furthermore, in the same manner as in the evaluation of normal physical properties, the test specimens were heated at 175°C for 504 hours to obtain test specimens after heating at 175°C. Then, using a durometer hardness tester (Type A), the hardness of the test specimens after heating at 190°C and the test specimens after heating at 175°C was measured in accordance with JIS K6253-3, and the hardness change was calculated according to the following formula. In the formula below, the hardness of the cross-linked rubber product is the hardness of the cross-linked rubber product measured in the normal physical properties test. The smaller the change in hardness after heating at 190°C, the better the heat resistance. Furthermore, the smaller the change in hardness after heating at 175°C, the better the heat resistance. Change in hardness due to heating at 190°C (points) = Hardness of test piece after heating at 190°C - Hardness of cross-linked rubber Change in hardness due to heating at 175°C (points) = Hardness of test piece after heating at 175°C - Hardness of cross-linked rubber

[0082] Example 1 Using a kneader, 100 parts of acrylic rubber (1) (trade name "Nipol H210X", manufactured by Zeon Corporation) were mixed with 55 parts of carbon black (1) (trade name "Seat SO", manufactured by Tokai Carbon Co., Ltd.), 1.5 parts of a polyether ester plasticizer (trade name "Adekacizer RS-735", manufactured by ADEKA Corporation), 2 parts of stearic acid, 1 part of an ester wax (trade name "Greg G-8205", manufactured by DIC Corporation), 2 parts of a mixture of styrenated diphenylamine and silica (66.7% by weight of styrenated diphenylamine and 33.3% by weight of silica, trade name "Nonflex LAS-P", manufactured by Seiko Chemical Co., Ltd.), and 0.1 parts of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (trade name "Nocrac CD", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and the mixture was mixed at 50°C for 7 minutes. The resulting mixture was transferred to a 50°C roll and mixed with 1 part 2,2-bis[4-(4-aminophenoxy)phenyl]propane (trade name "BAPP", manufactured by Seika Corporation, an aromatic polyvalent primary amine compound) and 2 parts of a mixture of dicyclohexylamine salt of ethylene glycol and long-chain alcohols (80% by weight of dicyclohexylamine salt of ethylene glycol and 20% by weight of long-chain alcohols [1-tetradecanol, 1-hexadecanol, 1-octadecanol], trade name "Knockmaster EGS", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.). The resulting mixture was kneaded with a roll to obtain an acrylic rubber composition. The resulting acrylic rubber composition was then subjected to measurements of Mooney viscosity and normal physical properties (hardness, tensile strength, elongation), as well as evaluations of extrusion scorch stability (Mooney scorch time t5), extrusion scorch stability, and heat resistance. The results are shown in Table 1.

[0083] <Example 2> An acrylic rubber composition was obtained in the same manner as in Example 1, except that acrylic rubber (2) (trade name "Hytenp H310X", manufactured by Zeon Corporation) was used instead of acrylic rubber (1), and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0084] Example 3 Except for changing the amount of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine used from 0.1 parts to 0.3 parts, an acrylic rubber composition was obtained in the same manner as in Example 1, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0085] Example 4 Except for changing the amount of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine used from 0.1 parts to 0.3 parts, an acrylic rubber composition was obtained in the same manner as in Example 2, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0086] <Example 5> Except for changing the amount of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine used from 0.1 parts to 0.5 parts, an acrylic rubber composition was obtained in the same manner as in Example 1, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0087] Example 6 Except for changing the amount of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine used from 0.1 parts to 0.5 parts, an acrylic rubber composition was obtained in the same manner as in Example 2, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0088] Example 7 An acrylic rubber composition was obtained in the same manner as in Example 1, except that 30 parts of carbon black (1) and 25 parts of carbon black (2) (trade name "Seast 116", manufactured by Tokai Carbon Co., Ltd.) were used instead of 55 parts of carbon black (1), and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine was not used, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0089] Example 8 Except for changing the amount of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine used from 0.1 parts to 2 parts and not using a mixture of styrenated diphenylamine and silica, an acrylic rubber composition was obtained in the same manner as in Example 2, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0090] <Comparative Example 1> An acrylic rubber composition was obtained in the same manner as in Example 1, except that 1,8-diazabicyclo[5,4,0]-undecene-7-ene (DBU) (trade name "RHENOGRAN XLA-60 (GE2014)", manufactured by RheinChemie, 60% DBU (including the portion that has become zinc dialkyl diphosphate salt)) was used instead of the mixture of dicyclohexylamine salt of ethylene glycol and long-chain alcohol, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine was not used, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0091] <Comparative Example 2> An acrylic rubber composition was obtained in the same manner as in Example 1, except that dimethylmyristylamine (trade name "Farmin DM4098", manufactured by Kao Corporation) was used instead of the mixture of dicyclohexylamine salt of ethylene glycol and long-chain alcohol, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine was not used, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0092] <Comparative Example 3> An acrylic rubber composition was obtained in the same manner as in Example 1, except that 1 part of a tertiary amine complex (trade name "VULCOFAC ACT-55", manufactured by BASF) was used instead of 2 parts of the mixture of dicyclohexylamine salt of ethylene glycol and long-chain alcohol, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine was not used, and measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0093] <Comparative Example 4> Using a kneader, 100 parts of acrylic rubber (1) were mixed with 65 parts of carbon black (1), 5 parts of polyetherester plasticizer, 2 parts of stearic acid, 1.5 parts of ester wax, and 2 parts of 4,4'-bis(α,α-dimethylbenzyl)diphenylamine for 7 minutes at 50°C. The resulting mixture was transferred to a roll at 50°C, and 0.5 parts of hexamethylenediamine carbamate (trade name "Diak#1", manufactured by DuPont Dow Elastomers) and 2 parts of 1,8-diazabicyclo[5,4,0]-undecene-7 (DBU) were added and kneaded with the roll to obtain an acrylic rubber composition. The resulting acrylic rubber composition was then measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0094] [Table 1]

[0095] The rubbers and compounding ingredients shown in Table 1 are as follows: Nipol H210X: Acrylic rubber (product name "Nipol H210X", manufactured by Zeon Corporation) Hytenp H310X: Acrylic rubber (product name "Hytenp H310X", manufactured by Zeon Corporation) SEAT SO: Carbon black (product name "SEAT SO", manufactured by Tokai Carbon Co., Ltd., inorganic filler) SEAT 116: Carbon black (product name "SEAT 116", manufactured by Tokai Carbon Co., Ltd.) Adeka Cizer RS-735: Polyetherester plasticizer (product name "Adeka Cizer RS-735", manufactured by ADEKA Corporation, plasticizer) Greg G-8205: Ester wax (product name "Greg G-8205", manufactured by DIC Corporation) Nonflex LAS-P: A mixture of styrenated diphenylamine and silica (66.7% by weight of styrenated diphenylamine and 33.3% by weight of silica, product name "Nonflex LAS-P", manufactured by Seiko Chemical Co., Ltd.) Nocrac CD: 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (trade name "Nocrac CD", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane (trade name "BAPP", manufactured by Seika Corporation, aromatic polyvalent primary amine compound) Knockmaster EGS: A mixture of dicyclohexylamine salt of ethylene glycol and long-chain alcohols (80% by weight of dicyclohexylamine salt of ethylene glycol and 20% by weight of long-chain alcohols [1-tetradecanol, 1-hexadecanol, 1-octadecanol], product name "Knockmaster EGS", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Diak#1: Hexamethylenediamine carbamate (trade name "Diak#1", manufactured by DuPont Dow Elastomers) RHENOGRAN XLA-60: 1,8-diazabicyclo[5,4,0]-undecene-7-ene (DBU) (trade name "RHENOGRAN XLA-60 (GE2014)", manufactured by RheinChemie, 60% DBU (including the zinc dialkyldiphosphate salt portion)) Farmin DM4098: Dimethylmyristylamine (trade name "Farmin DM4098", manufactured by Kao Corporation) ·VULCOFAC ACT-55: Tertiary amine complex (product name "VULCOFAC ACT-55", manufactured by BASF)

[0096] <Evaluation of Examples 1 to 8 and Comparative Examples 1 to 4> As can be seen from Table 1, the cross-linkable acrylic rubber compositions containing an acrylic rubber, an aromatic polyvalent primary amine compound, and an aliphatic monovalent secondary amine compound, in which the aliphatic monovalent secondary amine compound is a dicyclohexylamine compound or a dicyclohexylamine compound salt of ethylene glycol, were excellent in extrusion scorch stability and could produce cross-linked rubber products with excellent heat resistance (Examples 1 to 8). On the other hand, when the above-mentioned aliphatic monovalent secondary amine compound was not contained (Comparative Examples 1 to 4), or when the aromatic polyvalent primary amine compound was not contained (Comparative Example 4), the extrusion scorch stability was poor, and the heat resistance of the obtained cross-linked rubber product was poor.

[0097] <Examples 9 to 14> The components, excluding the mixture of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, dicyclohexylamine salt of ethylene glycol, and long-chain alcohol, were blended in the amounts shown in Table 2 and mixed at 50°C for 5 minutes. The resulting mixture was then transferred to a 50°C roll, and the mixture of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, dicyclohexylamine salt of ethylene glycol, and long-chain alcohol was blended and kneaded to obtain a cross-linkable rubber composition. The resulting cross-linkable rubber composition was used to obtain a sheet-shaped cross-linked rubber product in the same manner as in the evaluation of the normal physical properties described above.

[0098] The cross-linkable rubber compositions of Examples 9 to 14 also contain acrylic rubber, an aromatic polyvalent primary amine compound, and the above-mentioned specific aliphatic monovalent secondary amine compound, and therefore, like Examples 1 to 8, are considered to have excellent extrusion scorch stability, and the obtained cross-linked rubber products are considered to have excellent heat resistance.

[0099] [Table 2]

[0100] The ingredients shown in Table 2 are as follows (items similar to those in Table 1 are as described above). SEAT S: Carbon black (product name "SEAT S", manufactured by Tokai Carbon Co., Ltd.) Dexyclay: Calcined clay (trade name "Dexyclay", manufactured by Vanderbilt Minerals, LLC) Talc: Talc (product name "TT Talc", manufactured by Takehara Chemical Industry Co., Ltd.) A174: Silane coupling agent (product name "A174", manufactured by MOMENTIVE)

Claims

1. Contains acrylic rubber, aromatic polyvalent primary amine compounds, aliphatic monovalent secondary amine compounds, and alcohols, The crosslinkable acrylic rubber composition, wherein the aliphatic monovalent secondary amine compound is a dicycloalkylamine compound salt of ethylene glycol.

2. The crosslinkable acrylic rubber composition according to claim 1, further comprising a diphenylamine compound.

3. The crosslinkable acrylic rubber composition according to claim 2, wherein the diphenylamine compound is a styrenated diphenylamine.

4. 4. The crosslinkable acrylic rubber composition according to claim 2, wherein the diphenylamine compound is styrenated diphenylamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine.

5. The crosslinkable acrylic rubber composition according to any one of claims 1 to 4, which is used to form a hydraulic hose, an air hose, a turbo hose, or a tube.

6. A cross-linked rubber product obtained by cross-linking the cross-linkable acrylic rubber composition according to any one of claims 1 to 5.

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