A rubber toothed belt includes a belt main body including a plurality of tooth portions provided at predetermined intervals along a longitudinal direction of the belt and including a first rubber composition, in which the first rubber composition includes a composite polymer including a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt in a mass ratio of the former/the later=100/80 to 100/180, and includes, with respect to 100 parts by mass of the composite polymer, 3 parts by mass to 50 parts by mass of a zinc oxide, 3 parts by mass to 50 parts by mass of a non-reinforcing filler, 10 parts by mass or less of a reinforcing filler, 5 parts by mass or less of short fibers, and 1 part by mass to 5 parts by mass of an organic peroxide.

A rubber toothed belt includes a belt main body including a plurality of tooth portions provided at predetermined intervals along a longitudinal direction of the belt and including a first rubber composition, in which the first rubber composition includes a composite polymer including a hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt in a mass ratio of the former/the later=100/80 to 100/180, and includes, with respect to 100 parts by mass of the composite polymer, 3 parts by mass to 50 parts by mass of a zinc oxide, 3 parts by mass to 50 parts by mass of a non-reinforcing filler, 10 parts by mass or less of a reinforcing filler, 5 parts by mass or less of short fibers, and 1 part by mass to 5 parts by mass of an organic peroxide.

A coating agent for a rubber-coated cylinder head gasket contains a lubricant and a urethane resin. The lubricant is unsintered polytetrafluoroethylene resin particles having an average primary particle size of 1 μm or less. The amount of the unsintered polytetrafluoroethylene resin particles in a solid content is 30 to 80% by volume. The present invention provides a coating agent for a rubber-coated cylinder head gasket that can form a coat that is highly wear-resistant under high contact pressure and high temperature conditions and with which a rubber layer is less likely to stick to the seal face of the cylinder block or the cylinder head after the use under high contact pressure and high temperature conditions, and a cylinder head gasket obtained using the coating agent.

A method for producing a carboxy group-containing hydrogenated nitrile rubber includes a step of preparing a latex of a carboxy group-containing nitrile rubber by polymerizing a monomer mixture in a dispersive medium, the monomer mixture containing at least an α,β-ethylenically unsaturated nitrile monomer and a carboxy group-containing monomer; a step of heating the latex of the carboxy group-containing nitrile rubber at 50 to 85° C. in the state where the pH is adjusted in the range of 8.5 to 12; and a step of subjecting the latex of the carboxy group-containing nitrile rubber after the heating to a hydrogenation reaction in the presence of a hydrogenation catalyst in the state where the pH is adjusted in the range of 5 to 8.

Disclosed are thermoplastic vulcanizates comprising a plastic phase and a rubber phase and process for preparing such thermoplastic vulcanizates, wherein the plastic phase comprises a thermoplastic polymer and the rubber phase comprises a hydrogenated carboxylated nitrile rubber.

Disclosed are thermoplastic vulcanizates comprising a plastic phase and a rubber phase and process for preparing such thermoplastic vulcanizates, wherein the plastic phase comprises a thermoplastic polymer and the rubber phase comprises a hydrogenated carboxylated nitrile rubber.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit a nd 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic a cid monoester monomer unit, and having an iodine value of 120 or 1 ess, wherein a processability index Ipro (Ipro=CC×SA) is 0.003 0 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.

A nitrile group-containing copolymer rubber including 10 to 60 wt % of an α,β-ethylenically unsaturated nitrile monomer unit a nd 1 to 60 wt % of an α,β-ethylenically unsaturated dicarboxylic a cid monoester monomer unit, and having an iodine value of 120 or 1 ess, wherein a processability index Ipro (Ipro=CC×SA) is 0.003 0 or less, where the processability index Ipro is the product of the carboxyl group content CC, which is the number of moles of carboxyl groups per 100 g of nitrile group-containing copolymer rubber, and the absorbance area SA of a carboxylic anhydride group determined by infrared spectroscopy.

A hydrogenated NBR composition comprising 30 to 200 parts by weight of titanium oxide and 1 to 8 parts by weight of magnesium oxide, based on 100 parts by weight of hydrogenated NBR. By forming a crosslinked rubber layer of the rubber composition on a metal plate, a gasket material with excellent blister resistance, whose roll kneadability is improved without reducing the rubber strength of hydrogenated NBR, is provided. Moreover, the rubber composition is effective as a rubber raw material for use in soft metal or a high hardness hydrogenated NBR material for which kneading processing is difficult.

A hydrogenated NBR composition comprising 30 to 200 parts by weight of titanium oxide and 1 to 8 parts by weight of magnesium oxide, based on 100 parts by weight of hydrogenated NBR. By forming a crosslinked rubber layer of the rubber composition on a metal plate, a gasket material with excellent blister resistance, whose roll kneadability is improved without reducing the rubber strength of hydrogenated NBR, is provided. Moreover, the rubber composition is effective as a rubber raw material for use in soft metal or a high hardness hydrogenated NBR material for which kneading processing is difficult.