Abstract: A cross-linked rubber product is obtained by cross-linking an acrylic elastomer composition containing an acrylic elastomer obtained by copolymerization of an acrylate and a cross-linking site monomer. The molar fraction of an oxygen atom (a) in the acrylic elastomer is 11.3 mol % or less, the molar fraction of a nitrogen atom (b) in the acrylic elastomer is 0.5 mol % or less, and a volume change is from ?3 to 6% when the cross-linked rubber product is dipped in distilled water at 80° C. for 200 hours.

Abstract: A nitrile group-containing copolymer rubber contains ?,?-ethylenically unsaturated nitrile monomer units in a ratio of 10 to 60 wt % and has a Z-average radius of gyration of 100 nm or more. Preferably, the nitrile group-containing copolymer rubber has an iodine value of 120 or less. Further, preferably, the nitrile group-containing copolymer rubber has a plasticity number of 14 to 90. It is possible to provide a nitrile group-containing copolymer rubber able to give a cross-linked rubber excellent in tensile stress, compression set resistance, and low heat buildup property.

Abstract: A cross-linked rubber product is obtained by cross-linking an acrylic elastomer composition containing an acrylic elastomer obtained by copolymerization of an acrylate and a cross-linking site monomer. The molar fraction of an oxygen atom (a) in the acrylic elastomer is 11.3 mol % or less, the molar fraction of a nitrogen atom (b) in the acrylic elastomer is 0.5 mol % or less, and a volume change is from ?3 to 6% when the cross-linked rubber product is dipped in distilled water at 80° C. for 200 hours.

Abstract: An acrylic rubber contains (a) methyl methacrylate units, (b) ethyl acrylate units, (c) n-butyl acrylate units, (d) 2-methoxyethyl acrylate units, and (e) cross-linking site monomer units, in which the acrylic rubber contains 10 to 20% by weight of (a) the methyl methacrylate units, 15% by weight or less of (b) the ethyl acrylate units, 60 to 80% by weight of (c) the n-butyl acrylate units, 10 to 30% by weight of (d) the 2-methoxyethyl acrylate units, and 0.5 to 5% by weight of (e) the cross-linking site monomer units.

Abstract: The present invention aims to provide a laminate including a fluororubber layer and an acrylic rubber layer which are firmly bonded to each other and are not separated even at high temperatures. The laminate of the present invention includes a fluororubber layer and an acrylic rubber layer. The fluororubber layer is formed from a fluororubber composition containing a fluororubber that contains a polyol-crosslinkable vinylidene fluoride unit, a polyol crosslinker, and a crosslinking accelerator. The crosslinking accelerator is a quaternary phosphonium salt free from a chlorine atom. The fluororubber has an acid value of 0.20 KOHmg/g or higher.

Abstract: A nitrile group-containing copolymer rubber contains ?,?-ethylenically unsaturated nitrile monomer units in a ratio of 10 to 60 wt % and has a Z-average radius of gyration of 100 nm or more. Preferably, the nitrile group-containing copolymer rubber has an iodine value of 120 or less. Further, preferably, the nitrile group-containing copolymer rubber has a plasticity number of 14 to 90. It is possible to provide a nitrile group-containing copolymer rubber able to give a cross-linked rubber excellent in tensile stress, compression set resistance, and low heat buildup property.

Abstract: An acrylic rubber contains (a) methyl methacrylate units, (b) ethyl acrylate units, (c) n-butyl acrylate units, (d) 2-methoxyethyl acrylate units, and (e) cross-linking site monomer units, in which the acrylic rubber contains 10 to 20% by weight of (a) the methyl methacrylate units, 15% by weight or less of (b) the ethyl acrylate units, 60 to 80% by weight of (c) the n-butyl acrylate units, 10 to 30% by weight of (d) the 2-methoxyethyl acrylate units, and 0.5 to 5% by weight of (e) the cross-linking site monomer units.

Abstract: A cross-linkable nitrile rubber composition obtained by mixing a master batch (B) which contains a nitrile copolymer rubber (b1) having an iodine value of 120 or less and an aromatic polyvalent amine cross-linking agent (b2) into a carboxyl group-containing nitrile copolymer rubber (A) having an iodine value of 120 or less and a cross-linked product obtained by cross-linking the same are provided.

Abstract: A nitrile copolymer rubber composition contains a nitrile copolymer rubber (A) with an iodine value of 20 to 80 and white carbon with a specific surface area of 20 to 48 m2/g (B). A nitrile copolymer rubber composition is excellent in normal physical properties and is superior in compression set resistance under high temperature and low temperature conditions.

Abstract: A nitrile rubber composition containing a carboxyl group-containing nitrile rubber and a reactive silicone oil and cross-linked rubber obtained by using that nitrile rubber composition are provided. Further, a rubber composition for sliding member use containing a carboxyl group-containing rubber which contains carboxyl group-containing monomer units in a ratio of 0.1 to 20 wt %, a content ratio of monomer units which have unsaturated carbon-carbon double bonds of 20 wt % or less, and a content ratio of monomer units which have halogen atoms of 5 wt % or less and a reactive silicone oil is provided.

Abstract: A cross-linkable nitrile rubber composition obtained by mixing a master batch (B) which contains a nitrile copolymer rubber (b1) having an iodine value of 120 or less and an aromatic polyvalent amine cross-linking agent (b2) into a carboxyl group-containing nitrile copolymer rubber (A) having an iodine value of 120 or less and a cross-linked product obtained by cross-linking the same are provided.

Abstract: A rubber composition, including ?,?-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (A) having number average molecular weight of 50,000 to 150,000, ?,?-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (B) having number average molecular weight of 1,000 to 20,000, ethylene-?-olefin copolymer rubber (C), and a graft copolymer (D); wherein said graft copolymer (D) is obtained by performing graft copolymerization on a mixture of an aromatic vinyl compound and an ?,?-ethylenically unsaturated nitrile monomer with an ethylene-propylene-unconjugated copolymer, and a content of structure units of said ethylene-propylene-unconjugated copolymer is 20 to 70 wt %; a ratio of the graft copolymer (D) with respect to 100 parts by weight in total of said rubber (A), rubber (B) and rubber (C) is 1 to 30 parts by weight; and a composition ratio of the rubber (A), rubber (B) and rubber (C) is rubber (A): 20 to 79 wt %, rubber (B): 1 to 30 wt %, and rubber (C): 20 to 50 wt %, is subjected

Abstract: A rubber composition includes ?,?-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (A), ?,?-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (B), ethylene-?-olefin copolymer rubber (C), and a graft copolymer (D). The graft copolymer (D) is obtained by performing graft copolymerization on a mixture of an aromatic vinyl compound and an ?,?-ethylenically unsaturated nitrite monomer with an ethylene-propylene-unconjugated copolymer. A content of structure units of the ethylene-propylene-unconjugated copolymer is 20 to 70 wt %, a ratio of the graft copolymer (D) with respect to 100 parts by weight in total of said rubber (A), rubber (B) and rubber (C) is 1 to 30 parts by weight. A composition ratio of the rubber (A), rubber (B) and rubber (C) is rubber (A): 20 to 79 wt %, rubber (B): 1 to 30 wt %, and rubber (C): 20 to 50 wt %.

Abstract: A cross-linkable rubber composition comprised of a mixture of a carboxyl group-containing nitrile copolymer rubber (A) with a carboxyl group content per 100 g of 2×10?3 to 1×10?1 equivalents and a carboxyl group-containing acryl-based polymer (B) with a carboxyl group content per 100 g of 4×10?4 to 1×10?1 equivalents in a weight ratio A:B=40:60 to 90:10 into which a cross-linking agent (C) able to cross-link the carboxyl groups of both the nitrile copolymer rubber (A) and the acryl-based polymer (B) is blended, the amount blended of the cross-linking agent (C), converted to equivalents of functional groups able to react with carboxyl groups in the cross-linking agent, being 0.3 to 3 times equivalents of the total content of both the carboxyl groups of the nitrile copolymer rubber (A) and the acryl-based polymer (B) is used.

Abstract: A rubber composition, including &agr;,&bgr;-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (A) having number average molecular weight of 50,000 to 150,000, &agr;,&bgr;-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (B) having number average molecular weight of 1,000 to 20,000, ethylene-&agr;-olefin copolymer rubber (C), and a graft copolymer (D); wherein said graft copolymer (D) is obtained by performing graft copolymerization on a mixture of an aromatic vinyl compound and an &agr;,&bgr;-ethylenically unsaturated nitrile monomer with an ethylene-propylene-unconjugated copolymer, and a content of structure units of said ethylene-propylene-unconjugated copolymer is 20 to 70 wt % ; a ratio of the graft copolymer (D) with respect to 100 parts by weight in total of said rubber (A), rubber (B) and rubber (C) is 1 to 30 parts by weight; and a composition ratio of the rubber (A), rubber (B) and rubber (C) is rubber (A): 20 to 79 wt %, rubber (B) 1 to 30 wt %, and rubber (C):