Abstract: A nitrile group-containing rubber latex comprising an aqueous dispersion of a nitrile group-containing highly saturated rubber having an iodine value of not more than 120. The said rubber latex can be produced by converting a solution of a nitrile group-containing highly saturated polymer rubber having an iodine value of not more than 120 in an inert solvent into an oil-in-water emulsion using water and an emulsifier, and removing the solvent from the resulting emulsion.

Abstract: In a method for bonding a nitrile group-containing highly saturated polymer rubber having an iodine value of 120 or less to fibers on vulcanization, the improvement wherein fibers treated with an aqueous dispersion comprising a halogen-containing polymer latex and a resorcinol-formaldehyde resin are used.

Abstract: A rubber composition comprising 20 to 70% by weight of a first rubber component which is butyl rubber, a halogenated butyl rubber or a mixture of both as a first rubber component and 80 to 30% by weight of a second rubber component which is at least one rubber selected from chlorinated polyethylene rubber, chlorosulfonated polyethylene rubber and epichlorohydrin rubber, the first rubber component being dispersed as crosslinked rubber particles in the second rubber component.

Abstract: A process for the addition reaction of an unsaturated organic compound, except a rubber, having at least one carbon-carbon double bond in a molecule, which comprises reacting the unsaturated organic compound with an organic compound having a carboxyl group and an aldehyde group in the presence of a Lewis acid.

Abstract: A cis-1,4-polyisoprene rubber composition capable of giving a vulcanizate having improved strength, said composition comprising (1) a synthetic cis-1,4-polyisoprene rubber having epoxy groups, (2) a compound having at least two primary amino groups, and (3) a sulfur vulcanization system.

Abstract: A method for modifying a rubber having an unsaturated carbon bond which comprises reacting the rubber with an organic compound represented by the general formula ##STR1## wherein --R represents a hydrocarbon group, and --X is --H, --CN or ##STR2## in which --Y represents an organic atomic grouping, in the presence of a Lewis acid to introduce an ester group. Optionally, the ester group introduced is converted into a carboxyl group by chemically treating the reaction product.

Abstract: A method for modifying cis-1,4-polyisoprene rubber, which comprises reacting a diisocyanate with a primary diamine in the presence of the cis-1,4-polyisoprene rubber.

Abstract: A process for modifying a rubber, which comprises reacting a rubber having an unsaturated carbon linkage with an organic compound having a carboxyl group and an aldehyde group in the presence of an acid catalyst.

Abstract: A modified rubber composition comprising a blend of (a) a modified rubber obtained by reaction a rubber having an unsaturated carbon linkage with an organic compound having a carboxyl group and an aldehyde group in the presence of an acid catalyst, and (b) carbon black.

Abstract: A rubber composition for tire treads includes (Ia) an oil-extended rubber having a Mooney viscosity (ML.sub.1+4, 100.degree. C) of 20 to 70 which is prepared by adding 20 to 80 parts of a hydrocarbon oil to 100 parts by weight of a rubber terpolymer which is composed of 2 to 13% by weight of combined styrene, 15 to 70% by weight of combined 1,3-butadiene and 17 to 83% by weight of combined 1,3-pentadiene with the dienes having a total 1,4-bond content of at least 65 mole%, (II) vulcanization additives, and (III) 30 to 110 parts by weight, per 100 parts by weight of the oil-extended rubber (Ia), of a carbon black for rubber having an average particle diameter of not more than 60 m.mu. the rubbery copolymer has a glass transistion temperature of -70.degree. to -20.degree. C., and is produced by emulsion-polymerization at 0.degree. to 30.degree. C.