JP7136082B2 - Nitrile copolymer rubber composition, crosslinkable nitrile copolymer rubber composition, and crosslinked nitrile copolymer rubber - Google Patents

Description

The present invention relates to a nitrile copolymer rubber composition, a crosslinkable nitrile copolymer rubber composition, and a crosslinked nitrile copolymer rubber.

Conventionally, nitrile rubber having a relatively low iodine value, such as hydrogenated nitrile rubber, has been known as a rubber having excellent oil resistance, abrasion resistance, and heat resistance. Furthermore, in order to further improve the mechanical properties while maintaining such properties of nitrile rubber, a rubber composition is known in which microparticles such as resin are blended into nitrile rubber.

For example, Patent Literature 1 discloses a rubber composition in which fine particles of nylon are dispersed in a hydrogenated NBR elastomer matrix and which contains a functional group-containing ethylene copolymer. Patent Document 1 describes that the above configuration can provide a rubber composition excellent in mechanical properties (normal state properties) while maintaining the original heat resistance and wear resistance of hydrogenated NBR.

JP-A-10-251452

However, it cannot be said that the rubber composition described in Patent Document 1 is sufficient in terms of cold resistance and heat build-up.

In view of the above points, an object of one aspect of the present invention is to provide a nitrile copolymer rubber composition that has excellent cold resistance and low heat build-up.

One aspect of the present invention for solving the above problems is α,β-ethylenically unsaturated nitrile monomer units (a1) of 5% by weight or more and 20% by weight or less, and an α,β-ethylenically unsaturated dicarboxylic acid Monoester monomer unit (a2) 1% by weight or more and 60% by weight or less and α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) 35% by weight or more and 65% by weight or less , a carboxyl group-containing nitrile copolymer rubber (A) having an iodine value of 120 or less;
α,β-ethylenically unsaturated nitrile monomer unit (b1) 5% by weight or more and 20% by weight or less and α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) 36% by weight or more and 65% by weight % by weight or less and 20% by weight or more and 54% by weight or less of the conjugated diene monomer unit (b4), and the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) is containing a nitrile copolymer rubber (B) having an iodine value of 0.9% by weight or less and an iodine value of 120 or less and a polyamide resin; A nitrile copolymer rubber composition in which the weight ratio of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (b3) is 0.88 or more and 1.2 or less.

According to one aspect of the present invention, it is possible to provide a nitrile copolymer rubber composition having excellent cold resistance and low heat build-up.

Hereinafter, embodiments of the present invention will be described in detail.

<Nitrile copolymer rubber composition>
The nitrile copolymer rubber composition of the present embodiment comprises α,β-ethylenically unsaturated nitrile monomer units (a1) of 5% by weight or more and 20% by weight or less and an α,β-ethylenically unsaturated dicarboxylic acid monoester. Monomeric unit (a2) containing 1% by weight or more and 60% by weight or less and α,β-ethylenically unsaturated monocarboxylic acid ester monomeric unit (a3) containing 10% by weight or less and 65% by weight or less, and an iodine value is 120 or less, 5% by weight or more and 20% by weight or less of α,β-ethylenically unsaturated nitrile monomer units (b1), and α,β-ethylenically unsaturated It contains 10% by weight or more and 65% by weight or less of the saturated monocarboxylic acid ester monomer unit (b3), and the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) is 0.5% by weight. It contains a nitrile copolymer rubber (B) having an iodine value of 9% by weight or less and an iodine value of 120 or less, and a polyamide resin.

<Carboxyl Group-Containing Nitrile Copolymer Rubber (A)>
The carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment contains 5% by weight or more and 20% by weight or less of α,β-ethylenically unsaturated nitrile monomer units (a1) and α,β-ethylenic 1% by weight or more and 60% by weight or less of the unsaturated dicarboxylic acid monoester monomer unit (a2), and 10% by weight or more and 65% by weight or less of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) and has an iodine value of 120 or less. The carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment comprises an α,β-ethylenically unsaturated nitrile monomer, an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer, an α,β - Obtained by copolymerizing an ethylenically unsaturated monocarboxylic acid ester monomer and other copolymerizable monomers that are optionally added.

The α,β-ethylenically unsaturated nitrile monomer forming the α,β-ethylenically unsaturated nitrile monomer unit (a1) may be an α,β-ethylenically unsaturated compound having a nitrile group. Examples include acrylonitrile; α-halogenoacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; Among these, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred. The α,β-ethylenically unsaturated nitrile monomers may be used singly or in combination.

The content of the α,β-ethylenically unsaturated nitrile monomer units (a1) is 5% by weight or more with respect to the total monomer units constituting the carboxyl group-containing nitrile copolymer rubber (A), It is preferably 7 wt % or more, more preferably 10 wt % or more, and 20 wt % or less, preferably 18 wt % or less, more preferably less than 15 wt %. By making the α,β-ethylenically unsaturated nitrile monomer unit (a1) 5% by weight or more, the oil resistance of the obtained rubber crosslinked product can be improved, and by making it 20% by weight or less, , cold resistance and heat resistance can be improved.

Examples of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomers forming the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) include monomethyl maleate, monoethyl maleate, and maleic acid. monoalkyl maleate such as monopropyl and mono-n-butyl maleate; monocycloalkyl maleate such as monocyclopentyl maleate, monocyclohexyl maleate and monocycloheptyl maleate; monomethylcyclopentyl maleate and monoethyl maleate Maleic acid monoalkyl cycloalkyl esters such as cyclohexyl; fumaric acid monoalkyl esters such as monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono n-butyl fumarate; monocyclopentyl fumarate, monocyclohexyl fumarate, fumaric acid monocycloalkyl fumarate such as monocycloheptyl; monoalkylcycloalkyl fumarate such as monomethylcyclopentyl fumarate, monoethylcyclohexyl fumarate; monomethyl citraconate, monoethyl citraconate, monopropyl citraconate, mono-n-citraconate citraconic acid monoalkyl esters such as butyl; citraconic acid monocycloalkyl esters such as citraconic acid monocyclopentyl, citraconic acid monocyclohexyl, citraconic acid monocycloheptyl citraconic acid monoalkylcyclopentyl citraconic acid monoalkylcyclopentyl citraconic acid monomethylcyclopentyl, citraconic acid monoethylcyclohexyl citraconic acid monoalkylcyclohexyl Alkyl ester; monoalkyl itaconate such as monomethyl itaconate, monoethyl itaconate, monopropyl itaconate, monon-butyl itaconate; mono itaconate such as monocyclopentyl itaconate, monocyclohexyl itaconate, monocycloheptyl itaconate cycloalkyl esters; monoalkylcycloalkyl itaconates such as monomethylcyclopentyl itaconate and monoethylcyclohexyl itaconate; and the like. Among these, maleic acid monoalkyl esters are preferred, maleic acid monoalkyl esters in which the alkyl has 2 to 6 carbon atoms are more preferred, and maleic acid mono-n-butyl is particularly preferred. The α,β-ethylenically unsaturated dicarboxylic acid monoester monomers (a2) may be used singly or in combination.

The content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) is 1% by weight or more based on the total monomer units constituting the carboxyl group-containing nitrile copolymer rubber (A). , preferably 2% by weight or more and 60% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less. By setting the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) to 1% by weight or more, the tensile strength of the crosslinked rubber obtained can be improved, and the content is 60% by weight. % or less, it is possible to improve the compression set resistance and heat resistance of the obtained rubber crosslinked product.

α,β-ethylenic forming α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) forming α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) Examples of unsaturated monocarboxylic acid ester monomers include C1-C18 monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-dodecyl acrylate, methyl methacrylate and ethyl methacrylate. (Meth) acrylic acid alkyl ester having an alkyl group (abbreviation of “methacrylic acid alkyl ester and acrylic acid alkyl ester”. Same below.); (meth) methoxymethyl acrylate, (meth) methoxyethyl acrylate, (meth) ) ethoxymethyl acrylate, ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, i-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, (meth)acrylic acid i -Butoxyethyl, t-butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, alkoxyalkyl (meth)acrylate having an alkoxyalkyl group having 2 to 12 carbon atoms, such as methoxybutyl (meth)acrylate ; (meth)acrylate cyanoalkyl ester having a cyanoalkyl group having 2 to 12 carbon atoms such as α-cyanoethyl acrylate, α-cyanoethyl methacrylate, cyanobutyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxy acrylate (Meth)acrylic acid hydroxyalkyl esters having a hydroxyalkyl group having 1 to 12 carbon atoms such as propyl and 2-hydroxyethyl methacrylate; fluoro having 1 to 12 carbon atoms such as trifluoroethyl acrylate and tetrafluoropropyl methacrylate; (meth)acrylic acid fluoroalkyl ester having an alkyl group; A (meth)acrylic acid alkoxyalkyl ester having 2 to 12 alkoxyalkyl groups is preferred, and a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 10 carbon atoms and an alkoxyalkyl group having 2 to 8 carbon atoms. (Meth)acrylic acid alkoxyalkyl esters are preferred but more preferred, and n-butyl (meth)acrylate and methoxyethyl (meth)acrylate are particularly preferable. These may be used alone or in combination of multiple types.

The content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (a3) is preferably 10 wt. % or more, more preferably more than 30 wt%, still more preferably 35 wt% or more, particularly preferably 37 wt% or more, and preferably 65 wt% or less, more preferably 55 wt% or less, further preferably 50 wt% or more. % by weight or less. By setting the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) within the above range, it has sufficient normal physical properties, oil resistance, and compression set resistance, while maintaining cold resistance. The effect of the present invention of improving heat build-up and reducing heat build-up (improved heat build-up resistance) becomes even more pronounced.

Further, the carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment preferably contains conjugated diene monomer units (a4) so that the obtained crosslinked rubber has sufficient rubber elasticity.

Conjugated diene monomers forming the conjugated diene monomer unit (a4) include carbon such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene. A conjugated diene monomer having numbers 4 to 6 is preferred, 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is particularly preferred. Conjugated diene monomers may be used singly or in combination.

The content of the conjugated diene monomer units (a4) (including the portion saturated by hydrogenation etc.) is preferably 20% by weight or more, more preferably 25% by weight or more, still more preferably 35% by weight or more, particularly preferably 41% by weight or more, and preferably 84% by weight or less, more preferably 61% by weight or less, More preferably, it is 47% by weight or less. By setting the content of the conjugated diene monomer unit (a4) to 20% by weight or more, the rubber elasticity of the crosslinked rubber obtained can be improved, and by setting the content to 84% by weight or less, good heat resistance can be obtained. properties and chemical stability can be maintained.

Value of ratio of content of α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) to conjugated diene monomer unit (a4) (weight of (a3)/weight of (a4)) is preferably 0.68 or more, more preferably 0.8 or more, still more preferably 0.9 or more, and preferably 1.2 or less, more preferably 1.1 or less. Further, in the carboxyl group-containing nitrile copolymer rubber (A), if the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) is greater than the conjugated diene monomer unit (a4) ,preferable. By setting the ratio of the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) to the conjugated diene monomer unit (a4) within the above range, normal physical properties and oil resistance are improved. , the effect of improving cold resistance and reducing heat build-up while having sufficient compression set resistance becomes even more remarkable.

In addition, the value of the ratio of the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) to the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) ( (a3) weight/(a2) weight) is preferably 6.7 or more, more preferably 7.0 or more, still more preferably 7.8 or more, particularly preferably 8.5 or more, and preferably is 15 or less, more preferably 13 or less, and more preferably 11 or less.

The carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment is a carboxyl group-containing monomer other than the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer within a range that does not impair the effects of the present invention. may be copolymerized.

Examples of such carboxyl group-containing monomers include α,β-ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid, ethylacrylic acid, crotonic acid and cinnamic acid; fumaric acid and maleic acid; butenedioic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, allylmalonic acid, terraconic acid and the like. Examples of anhydrides of α,β-unsaturated polycarboxylic acids include α,β-ethylenically unsaturated polycarboxylic acid monomers such as maleic anhydride, itaconic anhydride, and citraconic anhydride; be done.

Containing carboxyl group-containing monomer units other than α,β-ethylenically unsaturated dicarboxylic acid monoester monomer units (a2) and α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (a3) The amount is preferably 20% by weight or less, more preferably 10% by weight or less, and still more preferably 5% by weight or less, based on the total monomer units constituting the carboxyl group-containing nitrile copolymer rubber (A).

Further, the carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment includes an α,β-ethylenically unsaturated nitrile monomer (a1) and an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer. Copolymerization of (a2), α,β-ethylenically unsaturated monocarboxylic acid ester monomer (a3), and conjugated diene monomer (a4) together with other monomers copolymerizable therewith may be Such other monomers include ethylene, α-olefin monomers, aromatic vinyl monomers, α,β-ethylenically unsaturated dicarboxylic acid dialkyl ester monomers, fluorine-containing vinyl monomers, A copolymerizable anti-aging agent and the like are exemplified.

The α-olefin monomer preferably has 3 to 12 carbon atoms, such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene.

Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinylpyridine and the like.

Examples of α,β-ethylenically unsaturated dicarboxylic acid dialkyl esters include dimethyl maleate, dimethyl fumarate, dimethyl itaconate, and diethyl itaconate.

Examples of fluorine-containing vinyl monomers include fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-trifluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene and tetrafluoroethylene.

Examples of copolymerizable antioxidants include N-(4-anilinophenyl) acrylamide, N-(4-anilinophenyl) methacrylamide, N-(4-anilinophenyl) cinnamamide, N-(4- anilinophenyl)crotonamide, N-phenyl-4-(3-vinylbenzyloxy)aniline, N-phenyl-4-(4-vinylbenzyloxy)aniline and the like.

These other copolymerizable monomers may be used in combination of multiple types. The content of other monomer units is preferably 50% by weight or less, more preferably 30% by weight or less, and more preferably 30% by weight or less, based on the total monomer units constituting the carboxyl group-containing nitrile copolymer rubber (A). Preferably, it is 10% by weight or less.

The iodine value of the carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment is preferably 120 or less, more preferably 60 or less, even more preferably 30 or less, and particularly preferably 15 or less. The use of a nitrile copolymer rubber having an iodine value of 120 or less (sometimes referred to as a highly saturated nitrile copolymer rubber) as the carboxyl group-containing nitrile copolymer rubber (A) improves the heat resistance of the resulting crosslinked rubber. can be done.

The polymer Mooney viscosity (ML1+4, 100°C) of the carboxyl group-containing nitrile copolymer rubber (A) is preferably 10 or more, more preferably 20 or more, still more preferably 30 or more, and preferably 200 or less, more preferably is 150 or less, more preferably 110 or less. When the polymer Mooney viscosity of the carboxyl group-containing nitrile copolymer rubber (A) is 10 or more, the mechanical properties of the resulting rubber crosslinked product can be improved. can improve sexuality.

The content of carboxyl groups in the carboxyl group-containing nitrile copolymer rubber (A), that is, the number of moles of carboxyl groups per 100 g of the carboxyl group-containing nitrile copolymer rubber (A) is preferably 0.006 ephr or more, more preferably 0. 0.012 ephr or more, more preferably 0.023 ephr, and preferably 0.116 ephr or less, more preferably 0.087 ephr, more preferably 0.058 ephr. When the carboxyl group content of the carboxyl group-containing nitrile copolymer rubber (A) is too low, the roll processability tends to deteriorate. On the other hand, if it is too large, the compression set resistance and heat resistance may decrease.

The method for producing the carboxyl group-containing nitrile copolymer rubber (A) used in the present embodiment is not particularly limited, but a copolymer rubber latex is prepared by copolymerizing the above-mentioned monomers by emulsion polymerization using an emulsifier. It is preferable to produce by hydrogenating this. In the emulsion polymerization, commonly used auxiliary materials for polymerization such as emulsifiers, polymerization initiators and molecular weight modifiers can be used.

Examples of emulsifiers include, but are not limited to, nonionic emulsifiers such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan alkyl esters; myristic acid, palmitic acid, and oleic acid. and salts of fatty acids such as linolenic acid, alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate, higher alcohol sulfate salts, anionic emulsifiers such as alkylsulfosuccinates; α,β-unsaturated carboxylic acid sulfoesters, α , β-unsaturated carboxylic acid sulfate esters, sulfoalkylaryl ethers and other copolymerizable emulsifiers; The amount of the emulsifier to be used is preferably 0.1 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of all the monomers.

The polymerization initiator is not particularly limited as long as it is a radical initiator. Potassium persulfate, sodium persulfate, ammonium persulfate, potassium perphosphate, inorganic peroxides such as hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5 -Organic peroxides such as trimethylhexanoyl peroxide and t-butyl peroxyisobutyrate; azo compounds; and the like. These polymerization initiators can be used alone or in combination of two or more. Inorganic or organic peroxides are preferred as polymerization initiators. When a peroxide is used as the polymerization initiator, it can be used as a redox polymerization initiator in combination with a reducing agent such as sodium bisulfite or ferrous sulfate. The amount of the polymerization initiator used is preferably 0.01 parts by weight or more and 2 parts by weight or less with respect to 100 parts by weight of all the monomers.

The molecular weight modifier is not particularly limited, but mercaptans such as t-dodecylmercaptan, n-dodecylmercaptan and octylmercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride and methylene bromide; α-methylstyrene dimer. sulfur-containing compounds such as tetraethylthiuram disulfide, dipentamethylene thiuram disulfide, and diisopropylxanthogen disulfide; These can be used alone or in combination of two or more. Among them, mercaptans are preferred, and t-dodecylmercaptan is more preferred. The amount of the molecular weight modifier used is preferably 0.1 parts by weight or more and 0.8 parts by weight or less with respect to 100 parts by weight of all the monomers.

Water is usually used as a medium for emulsion polymerization. The amount of water is preferably 80 parts by weight or more and 500 parts by weight or less with respect to 100 parts by weight of all the monomers.

In the emulsion polymerization, additional polymerization materials such as a stabilizer, a dispersant, a pH adjuster, an oxygen absorber, and a particle size adjuster can be used as necessary. When these are used, the type and amount used are not particularly limited.

In addition, when the iodine value of the copolymer obtained by copolymerization is higher than 120, the copolymer may be hydrogenated (hydrogenation reaction) in order to make the iodine value 120 or less. In this case, the hydrogenation method is not particularly limited, and a known method may be adopted.

<Nitrile copolymer rubber (B)>
The nitrile copolymer rubber (B) used in the present embodiment contains 5% by weight or more and 20% by weight or less of α,β-ethylenically unsaturated nitrile monomer units (b1) and α,β-ethylenically unsaturated monocarboxylic Containing 10% by weight or more and 65% by weight or less of the acid ester monomer unit (b3), and the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) is 0.9% by weight and the iodine value is 120 or less. The nitrile copolymer rubber (B) used in the present embodiment contains an α,β-ethylenically unsaturated nitrile monomer, an α,β-ethylenically unsaturated monocarboxylic acid ester monomer, and, if necessary, It is obtained by copolymerizing other copolymerizable monomers.

The α,β-ethylenically unsaturated nitrile monomer forming the α,β-ethylenically unsaturated nitrile monomer unit (b1) is similar to the carboxyl group-containing nitrile copolymer rubber (A) described above. can be used. The content of the α,β-ethylenically unsaturated nitrile monomer units (b1) in the nitrile copolymer rubber (B) is 5% by weight or more, preferably 7% by weight or more, more preferably 10% by weight or more, and preferably 20% by weight or less, more preferably less than 19% by weight, even more preferably 17% by weight or less, particularly preferably 15% by weight or less, particularly preferably less than 15% by weight. By making the α,β-ethylenically unsaturated nitrile monomer unit (b1) 5% by weight or more, the oil resistance of the resulting crosslinked rubber can be improved, and by making it 20% by weight or less, , can improve cold resistance.

Examples of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer forming the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) include the above-mentioned carboxyl group-containing nitrile copolymer rubber ( The same ones as in A) can be used, but carbon atoms of 1 or more such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-dodecyl acrylate, methyl methacrylate, ethyl methacrylate, etc. A (meth)acrylic acid alkyl ester having an alkyl group of 18 or less; is preferable, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 10 carbon atoms is more preferable, and n-butyl (meth)acrylate is particularly preferable. These may be used alone or in combination of multiple types.

The content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (b3) is preferably 10% by weight or more based on the total monomer units constituting the nitrile copolymer rubber (B), More preferably 15% by weight or more, still more preferably 36% by weight or more, still more preferably 41% by weight or more, particularly preferably 43% by weight or more, and preferably 65% by weight or less, more preferably 60% by weight or less , more preferably 55% by weight or less, particularly preferably 50% by weight or less. By setting the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) within the above range, it has sufficient normal physical properties, oil resistance, and compression set resistance, while maintaining cold resistance. The effect of improving heat buildup and reducing heat build-up becomes even more pronounced.

The nitrile copolymer rubber (B) used in the present embodiment is used as a monomer to be copolymerized with an α,β-ethylenically unsaturated nitrile monomer so that the resulting crosslinked rubber has rubber elasticity. , preferably a conjugated diene monomer. As the conjugated diene monomer, the same carboxyl group-containing nitrile copolymer rubber (A) as described above can be used. The content of the conjugated diene monomer units (including the portion saturated by hydrogenation or the like) (b4) in the nitrile copolymer rubber (B) is the total amount of units constituting the nitrile copolymer rubber (B) Preferably 20% by weight or more, more preferably 25% by weight or more, still more preferably 40% by weight or more, particularly preferably 41% by weight or more, and preferably 85% by weight or less, more preferably 85% by weight or more, based on the monomer unit It is preferably 77% by weight or less, more preferably 54% by weight or less. By setting the content of the conjugated diene monomer unit (b4) to 20% by weight or more, the rubber elasticity of the resulting crosslinked rubber can be improved, and by setting it to 85% by weight or less, good heat resistance can be obtained. properties and chemical stability can be maintained.

The nitrile copolymer rubber (B) used in the present embodiment includes an α,β-ethylenically unsaturated nitrile monomer, a conjugated diene monomer, and an α,β-ethylenically unsaturated monocarboxylic acid ester monomer. , may be obtained by copolymerizing other monomers copolymerizable therewith. Such other monomers include ethylene, α-olefin monomers, aromatic vinyl monomers, α,β-ethylenically Examples include saturated dicarboxylic acid dialkyl ester monomers, fluorine-containing vinyl monomers, copolymerizable anti-aging agents, and the like.

The nitrile copolymer rubber (B) used in the present embodiment may use an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer as another copolymerizable monomer. - The content of the ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) is preferably 0.9% by weight or less with respect to the total monomer units constituting the nitrile copolymer rubber (B). is 0.5% by weight or less, and the content of α,β-ethylenically unsaturated dicarboxylic acid monoester monomer units (b2) is particularly preferably 0% by weight. By setting the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) within the above range, compression set resistance and heat resistance can be improved. Examples of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer include those similar to the carboxyl group-containing nitrile copolymer rubber (A) described above.

Value of ratio of content of α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) to content of conjugated diene monomer unit (b4) (weight of (b3)/(b4) weight) is preferably 0.79 or more, more preferably 0.88 or more, still more preferably 0.93 or more, and preferably 1.2 or less, more preferably 1.1 or less. Also, in the nitrile copolymer rubber (B), it is preferable that the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (b3) is greater than the conjugated diene monomer units (b4). By setting the ratio of the content of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) to the conjugated diene monomer unit (b4) within the above range, cold resistance and heat resistance are improved. It is possible to maintain normal physical properties, oil resistance and compression set resistance while improving the properties.

The nitrile copolymer rubber (B) used in the present embodiment contains a carboxyl group-containing monomer other than the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer within a range that does not impair the effects of the present invention. It may be polymerized. However, the content of the carboxyl group-containing monomer units other than the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer is The content is preferably 5% by weight or less, more preferably 3% by weight or less, and particularly preferably 0% by weight of the carboxyl group-containing monomer units. If the content of the carboxyl group-containing monomer units is too high, the compression set resistance and heat resistance may deteriorate. Examples of the carboxyl group-containing monomer include those similar to the carboxyl group-containing nitrile copolymer rubber (A) described above.

The iodine value of the nitrile copolymer rubber (B) used in the present embodiment is preferably 120 or less, more preferably 60 or less, still more preferably 40 or less, and particularly preferably 30 or less. By setting the iodine value to 120 or less, the heat resistance of the resulting crosslinked rubber can be improved.

The polymer Mooney viscosity (ML1+4, 100°C) of the nitrile copolymer rubber (B) is preferably 10 or more, more preferably 20 or more, still more preferably 30 or more, preferably 2000 or less, more preferably 150 or less. and more preferably 110 or less. By setting the polymer Mooney viscosity of the nitrile copolymer rubber (B) to 10 or more, the mechanical properties of the resulting rubber crosslinked product can be improved, and by setting it to 200 or less, the processability of the rubber composition is improved. can be made

The content of carboxyl groups in the nitrile copolymer rubber (B), that is, the number of moles of carboxyl groups per 100 g of the nitrile copolymer rubber (B) is preferably 0.005 ephr or less, more preferably 0.003 ephr or less, 0 ephr is particularly preferred. By setting the carboxyl group content of the nitrile copolymer rubber (B) within the above range, the compression set resistance and heat resistance of the resulting crosslinked rubber can be improved.

The content ratio of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B) in the nitrile copolymer rubber composition is defined as "carboxyl group-containing nitrile copolymer rubber (A): nitrile copolymer rubber ( B)” weight ratio is preferably in the range of 2:98 to 98:2, more preferably in the range of 3:97 to 50:50, and particularly preferably in the range of 5:95 to 40:60. By setting the content ratio of the carboxyl group-containing nitrile copolymer rubber (A) to the nitrile copolymer rubber (B) within the above range, good normal physical properties and compression set resistance can be obtained.

The method for producing the nitrile copolymer rubber (B) used in the present invention is not particularly limited, but may be the same as that for the carboxyl group-containing nitrile copolymer rubber (A) described above.

<Polyamide resin>
The nitrile copolymer rubber composition of the present embodiment contains a polyamide resin in addition to the carboxyl group-containing nitrile copolymer rubber (A) and nitrile copolymer rubber (B) described above. In the present embodiment, the nitrile copolymer rubber includes an α,β-ethylenically unsaturated nitrile monomer unit (a1), an α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2), and A carboxyl group-containing nitrile copolymer rubber (A) having a content of α,β-ethylenically unsaturated monocarboxylic acid ester monomer units (a3) within a predetermined range, and an α,β-ethylenically unsaturated nitrile monomer The content of the body unit (b1) and the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) is within a predetermined range, and the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer A nitrile copolymer rubber cross-linked product obtained by using two kinds of rubber together, the nitrile copolymer rubber (B) having a unit (b2) content of not more than a predetermined amount, and blending this with a polyamide resin. Cold resistance and heat resistance can be improved while maintaining normal physical properties, oil resistance, and compression set resistance.

In order to improve the oil resistance of nitrile copolymer rubber, it is effective to mix polyamide resin with nitrile copolymer rubber. There is a possibility that the tensile strength and the like of the crosslinked product will decrease and the hardness will become too high. On the other hand, the above-described carboxyl group-containing nitrile copolymer rubber (A) and nitrile copolymer rubber (B) are used in combination, and a polyamide resin is blended therewith to obtain a carboxyl group-containing nitrile copolymer rubber (A). acts as a compatibilizer. Therefore, it is possible to improve the roll workability, improve the oil resistance and normal physical properties in the cross-linked rubber product, prevent the hardness from becoming too high, and furthermore, the compression permanent resistance. It can be excellent in distortion resistance, cold resistance, and heat resistance.

The polyamide resin used in the present embodiment is not limited as long as it is a polymer having an acid amide bond (-CONH-). For example, a polymer obtained by polycondensation of a diamine and a dibasic acid, a diamine derivative such as diformyl and a dibasic acid, a polymer obtained by polycondensation of a dibasic acid derivative such as dimethyl ester and a diamine, a polymer obtained by the reaction of a dinitrile or a diamide with formaldehyde, diisocyanate polymers obtained by polyaddition of nates and dibasic acids, polymers obtained by self-condensation of amino acids or derivatives thereof, polymers obtained by ring-opening polymerization of lactams, and the like. These polyamide resins may also contain polyether blocks.

Specific examples of polyamide resins include aliphatic polyamide resins such as nylon 46, nylon 6, nylon 66, nylon 610, nylon 612, nylon 11 and nylon 12; polyhexamethylenediamine terephthalamide, polyhexamethyleneisophthalamide, Aromatic polyamide resins such as xylene-containing polyamides are included. Among these, aliphatic polyamide resins are preferable, nylon 6, nylon 66, nylon 11 and nylon 12 are more preferable, and nylon 6, nylon 66 and nylon 12 are more preferable, since the effect of the present invention becomes more remarkable. Preferred, with nylon 66 and nylon 12 being particularly preferred.

The polyamide resin used in the present embodiment preferably has a melting point of 100 to 300°C, more preferably 120 to 280°C, still more preferably 150 to 280°C. By using one having a melting point of 100°C or higher, the heat resistance of the cross-linked rubber obtained can be improved. can improve sexuality. The melting point of the polyamide resin is the melting peak temperature measured by differential scanning calorimetry (DSC) defined in JIS K7121.

The content of the polyamide resin in the nitrile copolymer rubber composition of the present embodiment is the total of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B) (hereinafter referred to as "the content of the nitrile copolymer rubber The weight ratio of "total amount of nitrile copolymer rubber: content of polyamide resin" is preferably in the range of 95:5 to 50:50, more preferably 90:10 to It is in the range of 60:40. By setting the weight ratio to 95:5 or more, oil resistance and fuel oil resistance can be improved, and by setting the weight ratio to 50:50 or less, the hardness of the nitrile copolymer rubber composition is suitable for processing. can be

<Crosslinkable nitrile copolymer rubber composition>
The crosslinkable nitrile copolymer rubber composition of the present embodiment contains the nitrile copolymer rubber composition described above and a crosslinking agent.

Examples of cross-linking agents include organic peroxide cross-linking agents, sulfur cross-linking agents and polyamine cross-linking agents (hexamethylenediamine carbamate, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, etc.), Among these, the organic peroxide cross-linking agent is preferable because the effect of the present invention becomes more remarkable.

Conventionally known organic peroxide crosslinking agents can be used, and dicumyl peroxide, cumene hydroperoxide, t-butyl cumyl peroxide, paramenthane hydroperoxide, di-t-butyl peroxide, 1,3- Bis(t-butylperoxyisopropyl)benzene, 1,4-bis(t-butylperoxyisopropyl)benzene, 1,1-di-t-butylperoxy-3,3-trimethylcyclohexane, 4,4-bis-(t -butyl-peroxy)-n-butylvalerate, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3 , 1,1-di-t-butylperoxy-3,5,5-trimethylcyclohexane, p-chlorobenzoyl peroxide, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate and the like. Among these, 1,3-bis(t-butylperoxyisopropyl)benzene is preferred. These can be used individually by 1 type or in combination of multiple types.

The amount of the cross-linking agent in the cross-linkable nitrile copolymer rubber composition is preferably 0.00 parts per 100 parts by weight in total of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B). It is 5 parts by weight or more, more preferably 1 part by weight or more, still more preferably 2 parts by weight or more, and preferably 20 parts by weight or less, more preferably 15 parts by weight or less, still more preferably 10 parts by weight or less. If the amount of the cross-linking agent is too small, the compression set resistance of the obtained cross-linked rubber may be lowered. On the other hand, if it is too large, the fatigue resistance of the obtained crosslinked rubber may deteriorate.

The crosslinkable nitrile copolymer rubber composition of the present embodiment is preferably blended with a plasticizer, silica and/or a silane coupling agent, since the effects of the present invention become more pronounced.

Although the plasticizer is not particularly limited, for example, dibutoxyethyl adipate, di(butoxyethoxyethyl) adipate, di(methoxytetraethylene glycol) adipate, di(methoxypentaethylene glycol) adipate, adipic acid (methoxy Ester compounds of adipic acid and ether bond-containing alcohols such as tetraethylene glycol (methoxypentaethylene glycol); Esters of azelaic acid and ether bond-containing alcohols such as dibutoxyethyl azelate and di(butoxyethoxyethyl) azelate Compounds; Ester compounds of sebacic acid and ether bond-containing alcohols such as dibutoxyethyl sebacate and di(butoxyethoxyethyl) sebacate; Phthalic acid and ethers such as dibutoxyethyl phthalate and di(butoxyethoxyethyl) phthalate Ester compounds with bond-containing alcohols; Ester compounds of isophthalic acid and ether bond-containing alcohols, such as dibutoxyethyl isophthalate and di(butoxyethoxyethyl) isophthalate; di(2-ethylhexyl) adipate, diisodecyl adipate, adipine Dialkyl adipate compounds such as diisononyl acid and dibutyl adipate; di(2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate and other dialkyl azelate compounds; di-n-butyl sebacate, sebacic acid Dialkyl sebacate compounds such as di(2-ethylhexyl); dibutyl phthalate, di(2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diisodecyl phthalate, diundecyl phthalate, Dialkyl phthalate compounds such as diisononyl phthalate; dicycloalkyl phthalate compounds such as dicyclohexyl phthalate; aryl phthalate compounds such as diphenyl phthalate and butyl benzyl phthalate; di(2-ethylhexyl) isophthalate, isophthalate Dialkyl isophthalate compounds such as diisooctyl acid; Dialkyl tetrahydrophthalate compounds such as di(2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydrophthalate, and diisodecyl tetrahydrophthalate; Tri(2-ethylhexyl) trimellitate , tri-n-octyl trimellitate, triisodecyl trimellitate, trimellitic acid trimellitic acid derivatives such as triisooctyl, tri-n-hexyl trimellitate, triisononyl trimellitate and triisodecyl trimellitate; epoxy plasticizers such as epoxidized soybean oil and epoxidized linseed oil; Phosphate ester plasticizer; and the like. These can be used individually by 1 type or in combination of multiple types.

The amount of the plasticizer in the crosslinkable nitrile copolymer rubber composition is preferably 1 weight part with respect to a total of 100 parts by weight of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B). parts or more, preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 10 parts by weight or less.

Silica is not particularly limited as long as it is a compound containing (SiO ₂ ) in the composition formula. Specific examples include natural silica such as quartz powder and silica powder; synthetic silica such as silicic anhydride (silica gel, aerosil, etc.) and hydrated silicic acid; silicate metal salts; The above natural silica and synthetic silica have a composition formula of (SiO ₂ ) or (SiO ₂ ·nH ₂ O) (where n is a positive integer). Synthetic silica that is generally used as a so-called white reinforcing material (white carbon) as a reinforcing material for synthetic rubber can be used. These can be used individually by 1 type or in combination of multiple types. Silica can also be used in combination with fillers such as carbon black, calcium carbonate, clay, and talc, which will be described later.

The amount of silica compounded in the crosslinkable nitrile copolymer rubber composition of the present embodiment is preferably based on a total of 100 parts by weight of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B). is 0 parts by weight or more, more preferably 1 part by weight or more, still more preferably 5 parts by weight or more, and preferably 200 parts by weight or less, more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less.

Examples of the silane coupling agent include, but are not limited to, epoxy such as γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. silane coupling agents; vinyl silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane and vinyltris(2-methoxyethoxy)silane; methacryloxy silane coupling agents such as γ-(methacryloyloxypropyl)trimethoxysilane agents; amino-silane coupling agents such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane; mercapto-silane coupling agents such as γ-mercaptopropyltrimethoxysilane ; and the like. These can be used individually by 1 type or in combination of multiple types.

The amount of the silane coupling agent compounded in the crosslinkable nitrile copolymer rubber composition is preferably It is 0 parts by weight or more, more preferably 1 part by weight or more, and preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 10 parts by weight or less.

In addition to the above, the crosslinkable nitrile copolymer rubber composition may contain compounding agents normally used in the rubber field, such as reinforcing agents such as carbon black and short fibers, fillers such as calcium carbonate, clay and talc, and crosslinking accelerators. agents, cross-linking aids, cross-linking retarders, anti-aging agents, antioxidants, light stabilizers, scorch inhibitors such as primary amines, processing aids, lubricants, adhesives, lubricants, flame retardants, anti-mold agents, Acid agents, antistatic agents, pigments, foaming agents, etc. can be blended. The blending amount of these compounding agents is not particularly limited as long as it does not impair the purpose and effect of the present embodiment, and the amount can be blended according to the blending purpose.

The crosslinkable nitrile copolymer rubber composition may contain other polymers other than the above-described carboxyl group-containing nitrile copolymer rubber (A), nitrile copolymer rubber (B), and polyamide resin as long as the effects of the present invention are not impaired. may be blended. Other polymers include acrylic rubber, ethylene-acrylic acid copolymer rubber, fluororubber, styrene-butadiene copolymer rubber, polybutadiene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymer. Coalesced rubber, epichlorohydrin rubber, urethane rubber, chloroprene rubber, silicone rubber, fluorosilicone rubber, chlorosulfonated polyethylene rubber, natural rubber, polyisoprene rubber, and the like can be mentioned. When blending other polymers, the blending amount in the crosslinkable nitrile copolymer rubber composition is based on a total of 100 parts by weight of the carboxyl group-containing nitrile copolymer rubber (A) and the nitrile copolymer rubber (B). , preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 10 parts by weight or less.

<Production of nitrile copolymer rubber composition>
In the method for producing the nitrile copolymer rubber composition of the present embodiment, the carboxyl group-containing nitrile copolymer rubber (A), the nitrile copolymer rubber (B), and the polyamide resin are preferably kneaded at a temperature of 200° C. or higher. do.

The method of kneading these is not particularly limited, but extruders such as single-screw extruders and twin-screw extruders; closed kneaders such as kneaders, Banbury mixers, Brabender mixers, internal mixers and kneaders; roll kneaders and a method of mixing with a kneader such as; Among these, the method of kneading with a twin-screw extruder is particularly preferable because of its high production efficiency and dispersion efficiency.

The kneading temperature for kneading the carboxyl group-containing nitrile copolymer rubber (A), the nitrile copolymer rubber (B) and the polyamide resin is preferably 200°C or higher, more preferably 250°C or higher, and even more preferably 250°C or higher. 270° C. or higher. Also, the upper limit of the kneading temperature is preferably 400° C. or lower, particularly preferably 350° C. or lower. By setting the kneading temperature within the above range, the molten polyamide resin, the carboxyl group-containing nitrile copolymer rubber (A), and the nitrile copolymer rubber (B) can be sufficiently finely dispersed. And thereby, the effect of this invention becomes much more remarkable.

When kneading the carboxyl group-containing nitrile copolymer rubber (A), the nitrile copolymer rubber (B) and the polyamide resin, various compounding agents such as anti-aging agents and other rubbers may be mixed at the same time.

<Adjustment of crosslinkable nitrile copolymer rubber composition>
The method for preparing the crosslinkable nitrile copolymer rubber composition of the present embodiment is not particularly limited, but a crosslinking agent and a heat-labile component are added to the nitrile copolymer rubber composition of the present invention obtained as described above. Each component excepted is preferably kneaded at 10° C. or higher and 200° C. or lower, more preferably 20° C. or higher and 170° C. or lower in a mixer such as a Banbury mixer, a Brabender mixer, an intermixer, or a kneader, and transferred to a roll or the like. It can be prepared by adding a cross-linking agent, a heat-unstable cross-linking aid, etc., and then performing secondary kneading, preferably at a temperature of 10°C or higher and 80°C or lower.

<Rubber cross-linked product>
The rubber cross-linked product of the present embodiment is obtained by cross-linking the above-described cross-linkable nitrile copolymer rubber composition. The crosslinked rubber product is formed by using the crosslinkable nitrile copolymer rubber composition of the present embodiment, for example, by molding with a molding machine corresponding to a desired shape, such as an extruder, an injection molding machine, a compressor, a roll, etc., followed by heating. By doing so, a cross-linking reaction is carried out, and the cross-linked rubber product can be produced by fixing the shape. In this case, the cross-linking may be performed after pre-molding, or the cross-linking may be performed at the same time as the molding. The molding temperature is usually 10°C or higher and 200°C or lower, preferably 25°C or higher and 120°C or lower. The crosslinking temperature is generally 100° C. or higher and 200° C. or lower, preferably 130° C. or higher and 190° C. or lower, and the crosslinking time is generally 1 minute or longer and 24 hours or shorter, preferably 2 minutes or longer and 6 hours or shorter.

Further, depending on the shape, size, etc. of the cross-linked rubber product, even if the surface is cross-linked, the inside may not be sufficiently cross-linked, so secondary cross-linking may be performed by further heating.

As a heating method, a general method used for cross-linking rubber such as press heating, steam heating, oven heating, and hot air heating may be appropriately selected.

The rubber cross-linked product of the present invention thus obtained is obtained by cross-linking the cross-linkable nitrile copolymer rubber composition of the present embodiment described above, so that it is excellent in cold resistance and heat resistance, and Physical properties, oil resistance and compression set resistance are also sufficient.

Therefore, the cross-linked rubber product of the present embodiment can be used in O-rings, packings, oil seals, shaft seals, bearing seals, well head seals, seals for pneumatic equipment, cooling devices for air conditioners, and compressors for refrigerators in air conditioners. Fluorocarbon or carbon dioxide sealing seals used for cleaning, supercritical carbon dioxide or subcritical carbon dioxide sealing seals used as cleaning media for precision cleaning, rolling devices (rolling bearings, automotive hubs, etc.) units, water pumps for automobiles, linear guide devices, ball screws, etc.), intake manifold gaskets attached to the connection between the intake manifold and the cylinder head, cylinders attached to the connection between the cylinder block and the cylinder head. A unit comprising a head gasket, a rocker cover gasket that is attached to the joint between the rocker cover and the cylinder head, an oil pan gasket that is attached to the joint between the oil pan and the cylinder block or the transmission case, a positive electrode, an electrolyte plate and a negative electrode. It can be suitably used as various sealing materials such as gaskets for fuel cell separators mounted between a pair of housings sandwiching a cell, gaskets for top covers of hard disk drives, etc.; It can be particularly preferably used as a cold-resistant sealing material that can be used even in cold regions. Moreover, since it is excellent in heat resistance, it can be suitably used as an oil seal, a shaft seal, a bearing seal, and a seal for a rolling device.

EXAMPLES Hereinafter, embodiments of the present invention will be described more specifically with reference to examples and comparative examples. "Parts" and "%" are by weight unless otherwise specified. Physical properties and properties were tested and evaluated as follows.

<Rubber composition>
The content ratio of each monomer unit constituting each nitrile copolymer rubber was measured by the following method. That is, the content of mono-n-butyl maleate units was determined by adding 100 ml of 2-butanone to 0.2 g of a 2 mm square nitrile copolymer rubber and stirring for 16 hours, then adding 20 ml of ethanol and 10 ml of water and stirring. Using a 0.02N aqueous ethanol solution of potassium hydroxide, titration was performed at room temperature using thymolphthalein as an indicator to determine the number of moles of carboxyl groups per 100 g of nitrile copolymer rubber. It was calculated by converting to the amount of butyl units.

The content of 1,3-butadiene units and saturated butadiene units was calculated by measuring the iodine value (according to JIS K 6235) before and after hydrogenation using nitrile copolymer rubber. The acrylonitrile unit content was calculated by measuring the nitrogen content in the nitrile copolymer rubber by the Kjeldahl method according to JIS K6384. The content ratio of the n-butyl acrylate unit was calculated as the remaining component with respect to each of the above monomer units.

<Iodine value>
The iodine value of the nitrile copolymer rubber was measured according to JIS K6235.

<Mooney Viscosity (Polymer Mooney)>
The Mooney viscosity (Polymer Mooney) of the nitrile copolymer rubber was measured according to JIS K6300-1 (unit: [ML1+4, 100°C]).

<Normal physical properties (tensile strength, elongation, 100% tensile stress)>
A crosslinkable nitrile copolymer rubber composition is placed in a mold having a size of 15 cm long, 15 cm wide and 0.2 cm deep, and press-molded at 170° C. for 20 minutes at a press pressure of 10 MPa to obtain a crosslinked rubber sheet. Obtained. The resulting sheet-like crosslinked rubber product was punched out with a No. 3 dumbbell to prepare a test piece. Using the obtained test piece, the tensile strength, elongation, and 100% tensile stress of the crosslinked rubber were measured according to JIS K6251.

<Oil resistance test (immersion test)>
After obtaining a sheet-like cross-linked rubber product in the same manner as in the evaluation of the physical properties in the normal state, the cross-linked rubber product was subjected to test lubricating oil No. 1 at a temperature of 150° C. for 168 hours according to JIS K6258. 3 oil (trade name “IRM903”, manufactured by Nippon Sun Oil Co., Ltd.) to conduct an oil resistance test. Then, the volume of the rubber crosslinked product before and after immersion in the test oil is measured, and the volume change rate ΔV (unit: %) after immersion is expressed as "volume change rate ΔV = ([volume after immersion - volume before immersion] /Volume before immersion) x 100" to evaluate oil resistance. It can be judged that the smaller the value of the volume change rate ΔV, the smaller the degree of swelling due to lubricating oil and the better the oil resistance.

<Compression set resistance>
A crosslinkable nitrile copolymer rubber composition is placed in a mold having a diameter of 29 mm and a depth of 12.5 mm, and press-molded at 170° C. for 25 minutes at a press pressure of 10 MPa to obtain a cylindrical cross-linked rubber product. rice field. Using the obtained cross-linked rubber product, the rubber cross-linked product was placed in an environment of 150° C. for 168 hours in a state of being compressed by 25% according to JIS K6262, and then the compression set was measured. The smaller this value, the better the compression set resistance.

<Cold resistance test (Gehman torsion test)>
A sheet-like cross-linked rubber product was obtained in the same manner as in the evaluation of the normal physical properties described above, and a test piece having a length of 40 mm, a width of 3 mm, and a thickness of 2 mm was produced by punching out from the obtained sheet-like cross-linked rubber product. . Then, using the obtained test piece, the temperature (Gemann T10) at which the specific modulus becomes 10 was determined according to JIS K6261. The lower the Gehmann T10 value, the better the cold resistance.

<Fever test>
The crosslinkable nitrile copolymer rubber composition was placed in a mold having a diameter of 17.8 mm and a depth of 25 mm, and was heat-pressed at 170° C. for 25 minutes to obtain a cylindrical cross-linked rubber product. Then, using the obtained cross-linked rubber product, according to JIS K6265, a compression type flexometer was used to perform a temperature rise (°C ) was measured. The smaller the temperature rise, the better the heat resistance (low heat build-up).

<Synthesis Example 1: Production of carboxyl group-containing nitrile copolymer rubber (A-1)>
In a metal bottle, 180 parts of ion-exchanged water, 25 parts of a 10% by weight sodium dodecylbenzenesulfonate aqueous solution, 11 parts of acrylonitrile, 6 parts of mono-n-butyl maleate, 44 parts of n-butyl acrylate, t-dodecyl mercaptan (Molecular weight modifier) 0.75 part was charged in order, and after replacing the internal gas with nitrogen three times, 39 parts of 1,3-butadiene was charged. The metal bottle was kept at 5° C., 0.1 part of cumene hydroperoxide (polymerization initiator) was charged, and the polymerization reaction was carried out for 16 hours while rotating the metal bottle. Thereafter, 0.1 part of an aqueous hydroquinone solution (polymerization terminator) having a concentration of 10% by weight is added to terminate the polymerization reaction, and subsequently, residual monomers are removed using a rotary evaporator at a water temperature of 60° C., acrylonitrile-butadiene. A latex of n-butyl acrylate-mono n-butyl maleate copolymer rubber (solid content concentration: about 30% by weight) was obtained.

Next, a palladium catalyst (a solution obtained by mixing a 1% by weight palladium acetate acetone solution and an equal weight of ion-exchanged water) was added to the autoclave so that the palladium content was 2000 ppm with respect to the rubber weight contained in the latex. Then, a hydrogenation reaction was carried out at a hydrogen pressure of 3 MPa and a temperature of 50° C. for 6 hours to obtain a latex of carboxyl group-containing nitrile copolymer rubber (A-1).

Then, twice the volume of methanol is added to the latex of the obtained carboxyl group-containing nitrile copolymer rubber (A-1) to coagulate it, followed by vacuum drying at 60° C. for 12 hours to obtain a carboxyl group-containing nitrile copolymer rubber. (A-1) was obtained. The composition of the obtained carboxyl group-containing nitrile copolymer rubber (A-1) was 11.0% by weight of acrylonitrile units, 4.5% by weight of mono-n-butyl maleate units, and butadiene units (including hydrogenated ) 41.2% by weight, 43.3% by weight of n-butyl acrylate units, an iodine value of 9, and a polymer Mooney viscosity (ML1+4, 100° C.) of 42. Table 1 shows the composition and properties of the carboxyl group-containing nitrile copolymer rubber (A-1).

<Synthesis Example 2: Production of carboxyl group-containing nitrile copolymer rubber (A-2)>
Carboxyl group-containing in the same manner as in Production Example 1 except that the amount of acrylonitrile was changed to 16 parts, the amount of n-butyl acrylate was changed to 36 parts, and the amount of 1,3-butadiene was changed to 42 parts. A nitrile copolymer rubber (A-2) was obtained. The resulting carboxyl group-containing nitrile copolymer rubber (A-2) had a composition of 15.6% by weight of acrylonitrile units, 4.5% by weight of mono-n-butyl maleate units, and butadiene units (including hydrogenated ) 43.3% by weight, 36.6% by weight of n-butyl acrylate units, an iodine value of 9, and a polymer Mooney viscosity (ML1+4, 100° C.) of 42. Table 1 shows the composition and properties of the carboxyl group-containing nitrile copolymer rubber (A-2).

<Synthesis Example 3: Production of carboxyl group-containing nitrile copolymer rubber (A-3)>
Carboxyl group-containing in the same manner as in Production Example 1, except that the amount of acrylonitrile was changed to 19 parts, the amount of n-butyl acrylate was changed to 33 parts, and the amount of 1,3-butadiene was changed to 42 parts. A nitrile copolymer rubber (A-3) was obtained. The resulting carboxyl group-containing nitrile copolymer rubber (A-3) had a composition of 18.2% by weight of acrylonitrile units, 4.5% by weight of mono-n-butyl maleate units, and butadiene units (including hydrogenated ) 43.1% by weight, 34.2% by weight of n-butyl acrylate units, an iodine value of 9, and a polymer Mooney viscosity (ML1+4, 100° C.) of 42. Table 1 shows the composition and properties of the carboxyl group-containing nitrile copolymer rubber (A-3).

<Synthesis Example 4: Production of carboxyl group-containing nitrile copolymer rubber (A-4)>
Carboxyl group-containing in the same manner as in Production Example 1, except that the amount of acrylonitrile was changed to 21 parts, the amount of n-butyl acrylate was changed to 42 parts, and the amount of 1,3-butadiene was changed to 31 parts. A nitrile copolymer rubber (A-4) was obtained. The composition of the obtained carboxyl group-containing nitrile copolymer rubber (A-4) was 20.9% by weight of acrylonitrile units, 40.4% by weight of butadiene units (including hydrogenated ones), and mono-n-butyl maleate. The unit content was 4.5% by weight, the n-butyl acrylate unit content was 34.2% by weight, the iodine value was 9, and the polymer Mooney viscosity (ML1+4, 100°C) was 42. Table 1 shows the composition and properties of the carboxyl group-containing nitrile copolymer rubber (A-4).

<Synthesis Example 5: Production of nitrile copolymer rubber (B-1)>
Into the reactor, 200 parts of ion-exchanged water and 2.25 parts of fatty acid potassium soap (potassium salt of fatty acid) were added to prepare an aqueous soap solution. Then, 11 parts of acrylonitrile, 46 parts of n-butyl acrylate and 0.5 parts of t-dodecyl mercaptan (molecular weight modifier) were added in this order to this soapy water solution, and after replacing the internal gas with nitrogen three times, , 42 parts of 3-butadiene were charged. Next, the inside of the reactor was kept at 5° C., 0.1 part of cumene hydroperoxide (polymerization initiator) was charged, and the polymerization reaction was carried out for 16 hours while stirring. Then, 0.1 part of an aqueous solution of hydroquinone (polymerization terminator) having a concentration of 10% is added to terminate the polymerization reaction, and residual monomers are removed using a rotary evaporator at a water temperature of 60° C. to copolymerize the nitrile. A latex of rubber (B-1) (solid content concentration: about 25% by weight) was obtained.

Next, the latex obtained above was added to an aqueous solution of aluminum sulfate in an amount of 3% by weight based on the nitrile copolymer rubber content, stirred to coagulate the latex, washed with water and filtered. After that, it was vacuum-dried at 60° C. for 12 hours to obtain a nitrile copolymer rubber. Then, the obtained nitrile copolymer rubber was dissolved in acetone to a concentration of 12% and put into an autoclave. The hydrogenation reaction was carried out at a temperature of 50°C.

After completion of the hydrogenation reaction, the mixture was poured into a large amount of water to solidify, separated by filtration and dried to obtain a nitrile group-containing copolymer rubber (B-1). The composition of the obtained nitrile group-containing copolymer rubber (A2-1) was 10.8% by weight of acrylonitrile units, 43.6% by weight of 1,3-butadiene units (including hydrogenated portions), and acrylic acid. The content of n-butyl units was 45.6% by weight, the iodine value was 9, and the polymer Mooney viscosity [ML1+4, 100° C.] was 65. Table 2 shows the composition and properties of the nitrile copolymer rubber (B-1).

<Synthesis Example 6: Production of nitrile copolymer rubber (B-2)>
Carboxyl group-containing in the same manner as in Production Example 5 except that the amount of acrylonitrile was changed to 15 parts, the amount of n-butyl acrylate was changed to 42 parts, and the amount of 1,3-butadiene was changed to 31 parts. A nitrile copolymer rubber (B-2) was obtained. The composition of the obtained carboxyl group-containing nitrile copolymer rubber (B-2) was 15.4% by weight of acrylonitrile units, 43.0% by weight of butadiene units (including hydrogenated ones), and n-butyl acrylate units. The iodine value was 9 and the polymer Mooney viscosity (ML1+4, 100° C.) was 68. Table 2 shows the composition and properties of the nitrile copolymer rubber (B-2).

<Synthesis Example 7: Production of nitrile copolymer rubber (B-3)>
Carboxyl group-containing in the same manner as in Production Example 5 except that the amount of acrylonitrile was changed to 18 parts, the amount of n-butyl acrylate was changed to 42 parts, and the amount of 1,3-butadiene was changed to 40 parts. A nitrile copolymer rubber (B-3) was obtained. The composition of the obtained carboxyl group-containing nitrile copolymer rubber (B-3) was 17.8% by weight of acrylonitrile units, 42.8% by weight of butadiene units (including hydrogenated ones), and n-butyl acrylate units. It had an iodine value of 9 and a polymer Mooney viscosity (ML1+4, 100° C.) of 70. Table 2 shows the composition and properties of the nitrile copolymer rubber (B-3).

<Synthesis Example 8: Production of nitrile copolymer rubber (B-4)>
Carboxyl group-containing in the same manner as in Production Example 5, except that the amount of acrylonitrile was changed to 24 parts, the amount of n-butyl acrylate was changed to 37 parts, and the amount of 1,3-butadiene was changed to 39 parts. A nitrile copolymer rubber (B-4) was obtained. The composition of the obtained carboxyl group-containing nitrile copolymer rubber (B-4) was 23.6% by weight of acrylonitrile units, 40.8% by weight of butadiene units (including hydrogenated ones), and n-butyl acrylate units. It had an iodine value of 10 and a polymer Mooney viscosity (ML1+4, 100° C.) of 71. Table 2 shows the composition and properties of the nitrile copolymer rubber (B-4).

<Example 1>
20 parts of the carboxyl group-containing nitrile copolymer rubber (A-1) obtained in Synthesis Example 1 and 50 parts of the nitrile copolymer rubber (B-1) obtained in Synthesis Example 5 were pulverized with a pulverizer and mixed with a Henschel mixer. After mixing with , it was fed into a twin-screw extruder at 35 kg/h by a weight feeder. From the same inlet, nylon 66 (trade name “Amilan (registered trademark) CM3006” manufactured by Toray Industries, Inc., melting point 265 ° C. as a polyamide resin (the melting point of the polyamide resin is defined by JIS K7121 by differential scanning calorimetry (DSC) is the melting peak temperature measured by )) was fed into a twin-screw extruder at 15 kg/h using a weight feeder and kneaded to obtain a nitrile copolymer rubber composition. As a twin-screw extruder, the value of the ratio of screw length L to screw diameter D (L/D) is 45, and has an input block portion and first to tenth block portions, and a fifth block and a block having a vent port in the ninth block. The screw configuration has a first mixing section just before the fifth block vent, and a second kneading section and a third mixing section between the fifth and ninth block vents. of the kneading section. Kneading was carried out under the conditions that the temperature of all blocks was 290° C. and the number of screw revolutions was 120 rpm.

Using a Banbury mixer, 100 parts of the nitrile copolymer rubber composition obtained above was added with 20 parts of carbon black FEF (trade name “Seist (registered trademark) SO”, manufactured by Tokai Carbon Co., Ltd., carbon black), trimerit Tri-2-ethylhexyl acid (trade name “Adekasizer (registered trademark) C-8” manufactured by ADEKA, plasticizer) 5 parts, stearic acid (processing aid) 0.5 parts, polyoxyethylene alkyl ether phosphate ester (trade name “Phosphanol (registered trademark) RL210”, manufactured by Toho Chemical Industry Co., Ltd., processing aid) 0.5 parts, mercaptobenzimidazole (trade name “Noclac (registered trademark) MB”, Ouchi Shinko Kagaku Co., Ltd.) Antioxidant) 1 part, 4,4′-di-(α,α-dimethylbenzyl)diphenylamine (trade name “Nocrac (registered trademark) CD”, antiaging agent manufactured by Ouchi Shinko Kagaku Co., Ltd.) 1 part is added and kneaded, and then the mixture is transferred to a roll and 1,3-bis(t-butylperoxyisopropyl)benzene 40% product (trade name “VulCup (registered trademark) 40KE”, manufactured by Arkema, organic filtration A crosslinkable nitrile copolymer rubber composition was obtained by adding 7 parts of an oxide crosslinking agent) and kneading.

Then, by the above-described methods, evaluations and tests were performed for normal physical properties, oil resistance, compression set resistance, cold resistance, and heat build-up. Table 3 shows the results.

<Example 2>
Using 20 parts of carboxyl group-containing nitrile copolymer rubber (A-2) instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1), and replacing 50 parts of nitrile copolymer rubber (B-1) with nitrile copolymer rubber A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as in Example 1 except that 50 parts of the polymer rubber (B-2) was used, and the evaluation was performed in the same manner. Table 3 shows the results.

<Example 3>
Using 20 parts of carboxyl group-containing nitrile copolymer rubber (A-3) instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1), and replacing 50 parts of nitrile copolymer rubber (B-1) with nitrile copolymer rubber A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as in Example 1 except that 50 parts of the polymer rubber (B-3) was used, and the evaluation was performed in the same manner. Table 3 shows the results.

<Example 4>
Instead of 20 parts of carbon black FEF (trade name “Seist (registered trademark) SO”, manufactured by Tokai Carbon Co., carbon black), carbon black FEF (trade name “Seist (registered trademark) SO” manufactured by Tokai Carbon Co., carbon Black) and 15 parts of synthetic silica (trade name “Nipsil (registered trademark) ER”, manufactured by Tosoh Silica Co., Ltd., silica) were used in the same manner as in Example 1 to prepare a crosslinkable nitrile copolymer rubber composition. was created and evaluated in the same way. Table 3 shows the results.

<Example 5>
Instead of 20 parts of carbon black FEF (trade name “Seist (registered trademark) SO”, manufactured by Tokai Carbon Co., Ltd., carbon black), surface-treated silica (trade name “Aerosil (registered trademark) R972V” manufactured by Evonik Degussa, Surface-treated silica) 25 parts, and a silane coupling agent (trade name “Dynasilane (registered trademark) MEMO”, manufactured by Evonik, silane coupling agent) were used in the same manner as in Example 1, except that a crosslinkable nitrile co-polymer was used. Polymerized rubber compositions were prepared and evaluated in the same manner. Table 3 shows the results.

<Example 6>
Crosslinkable nitrile copolymerization was carried out in the same manner as in Example 1, except that 10 parts of zinc methacrylate (trade name “Sunester (registered trademark) SK-30”, manufactured by Sanshin Chemical Co., Ltd., a cross-linking aid) was further added. A rubber composition was prepared and evaluated in the same manner. Table 3 shows the results.

<Comparative Example 1>
Using a Banbury mixer, 20 parts of the carboxyl group-containing nitrile copolymer rubber (A-1) obtained in Synthesis Example 1, 80 parts of the nitrile copolymer rubber (B-1), carbon black FEF (trade name "Seist (registered Trademark) SO”, manufactured by Tokai Carbon Co., Ltd., carbon black) 60 parts, tri-2-ethylhexyl trimellitate “trade name “Adekasizer (registered trademark) C-8” manufactured by ADEKA, plasticizer) 5 parts, stearic acid (Processing aid) 0.5 parts, polyoxyethylene alkyl ether phosphate (trade name “Phosphanol (registered trademark) RL210” manufactured by Toho Chemical Industry Co., Ltd., processing aid) 0.5 parts, mercaptobenz Imidazole ("Noclac (registered trademark) MB", manufactured by Ouchi Shinko Kagaku Co., Ltd., anti-aging agent) 1 part, 4,4'-di-(α,α-dimethylbenzyl) diphenylamine (trade name "Noclac (registered trademark) CD", Ouchi Shinko Kagaku Co., Ltd., anti-aging agent) is added and kneaded, and then the mixture is transferred to a roll to obtain 1,3-bis(t-butylperoxyisopropyl)benzene 40% product (product A crosslinkable nitrile copolymer rubber composition was obtained by adding 7 parts of an organic peroxide crosslinking agent (named "VulCup (registered trademark) 40KE", manufactured by Arkema) and kneading.

Then, according to the methods described above, evaluations and tests of normal physical properties, fuel oil resistance test, compression set resistance test, and cold resistance test were carried out. Table 4 shows the results.

<Comparative Example 2>
Using 20 parts of carboxyl group-containing nitrile copolymer rubber (A-2) instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1), replacing 80 parts of nitrile copolymer rubber (B-1) with nitrile copolymer rubber A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as in Comparative Example 1 except that 80 parts of the polymer rubber (B-2) was used, and the evaluation was performed in the same manner. Table 4 shows the results.

<Comparative Example 3>
Using 20 parts of carboxyl group-containing nitrile copolymer rubber (A-3) instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1), and replacing 80 parts of nitrile copolymer rubber (B-1) with nitrile copolymer rubber A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as in Comparative Example 1 except that 80 parts of the polymer rubber (B-3) was used, and the evaluation was performed in the same manner. Table 4 shows the results.

<Comparative Example 4>
Using 20 parts of carboxyl group-containing nitrile copolymer rubber (A-4) instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1), and replacing 50 parts of nitrile copolymer rubber (B-1) with nitrile copolymer rubber A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as in Example 1 except that 50 parts of the polymer rubber (B-4) was used, and the evaluation was performed in the same manner. Table 4 shows the results.

<Comparative Example 5>
Example 1 except that 70 parts of nitrile copolymer rubber (B-1) was used instead of 20 parts of carboxyl group-containing nitrile copolymer rubber (A-1) and 50 parts of nitrile copolymer rubber (B-1). A crosslinkable nitrile copolymer rubber composition was prepared in the same manner as above and evaluated in the same manner. Table 4 shows the results.

As is clear from Tables 3 and 4, carboxyl group-containing nitrile copolymer rubber (A-1), (A-2) or (A-3) and nitrile copolymer rubber (B-1), (B-2) ) or (B-4) and a polyamide resin in predetermined amounts (Examples 1 to 6), the crosslinked rubber obtained has excellent cold resistance and heat resistance. In addition, the normal physical properties, oil resistance, and compression set resistance were also sufficient.

As described above, the embodiments of the present invention have been described with reference to examples, but the present invention is not limited to specific embodiments and examples, and various can be modified and changed.

This application claims priority based on Japanese Patent Application No. 2017-059957 filed with the Japan Patent Office on March 24, 2017, the entire contents of which are incorporated herein by reference.

Claims (10)

α,β-ethylenically unsaturated nitrile monomer units (a1) of 5% by weight or more and 20% by weight or less, and α,β-ethylenically unsaturated dicarboxylic acid monoester monomer units (a2) of 1% by weight or more and 60% by weight or more. A carboxyl group-containing nitrile copolymer having an iodine value of 120 or less, containing 35% by weight or more and 65% by weight or less of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) and 35% by weight or less and 65% by weight or less of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3). rubber (A);
α,β-ethylenically unsaturated nitrile monomer unit (b1) 5% by weight or more and 20% by weight or less and α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) 36% by weight or more and 65% by weight % by weight or less and 20% by weight or more and 54% by weight or less of the conjugated diene monomer unit (b4), and the content of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (b2) is a nitrile copolymer rubber (B) having an iodine value of 0.9% by weight or less and an iodine value of 120 or less;
containing a polyamide resin,
The ratio of the weight of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (b3) to the weight of the conjugated diene monomer unit (b4) is 0.88 or more and 1.2. A nitrile copolymer rubber composition as follows. 2. The nitrile copolymer rubber composition according to claim 1, wherein the weight ratio of the carboxyl group-containing nitrile copolymer rubber (A) to the weight of the nitrile copolymer rubber (B) is 2:98 to 98:2. . The nitrile copolymer rubber composition according to claim 1 or 2, wherein the polyamide resin has a melting point of 100 to 300°C. 4. Any one of claims 1 to 3, wherein the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) of the carboxyl group-containing nitrile copolymer rubber (A) is a maleic acid monoalkyl ester unit. The nitrile copolymer rubber composition according to any one of items. The carboxyl group-containing nitrile copolymer rubber (A) further contains 20% by weight or more and 47% by weight or less of the conjugated diene monomer unit (a4), and the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer. Containing the body unit (a2) at 1% by weight or more and 20% by weight or less,
The ratio of the weight of the α,β-ethylenically unsaturated monocarboxylic acid ester monomer unit (a3) to the weight of the conjugated diene monomer unit (a4) is 0.68 or more and 1.2 or less. The nitrile copolymer rubber composition according to any one of claims 1 to 4. The ratio of the weight of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a3) to the weight of the α,β-ethylenically unsaturated dicarboxylic acid monoester monomer unit (a2) is , 7.0 or more and 15 or less, the nitrile copolymer rubber composition according to any one of claims 1 to 5. The content of the α,β-ethylenically unsaturated nitrile monomer unit (a1) in the carboxyl group-containing nitrile copolymer rubber (A) is 5% by weight or more and less than 15% by weight, and the nitrile copolymer rubber 7. The content of the α,β-ethylenically unsaturated nitrile monomer unit (b1) in (B) is 5% by weight or more and less than 15% by weight, according to any one of claims 1 to 6 A nitrile copolymer rubber composition. A crosslinkable nitrile copolymer rubber composition obtained by blending the nitrile copolymer rubber composition according to any one of claims 1 to 7 with a crosslinking agent. A crosslinked nitrile copolymer rubber obtained by crosslinking the crosslinkable nitrile copolymer rubber composition according to claim 8 . The crosslinked nitrile copolymer rubber according to claim 9, which is used as a sealing material.