Abstract: An saturated nitrile-conjugated diene copolymer obtained by copolymerizing acrylonitrile with butadiene in the presence of a free radical initiator and an alkylthiol compound as a molecular weight modifier. A part of the molecular weight modifier is incorporated in a monomer charge before polymerization, and the remainder thereof is incorporated in a polymerization mixture during polymerization. The alkylthiol compound has 12 to 16 carbon atoms, which include at least three tertiary carbon atoms, and further has a sulfur atom directly bound to at least one of the tertiary carbon atoms. The copolymer has a Mooney viscosity of 15 to 150 and contains 3 to 20 weight % of a fraction having a number average molecular weight of not larger than 35,000. The copolymer is used in combination with a sulfur-containing vulcanizer.

Abstract: An saturated nitrile-conjugated diene copolymer obtained by copolymerizing acrylonitrile with butadiene in the presence of a free radical initiator and an alkylthiol compound as a molecular weight modifier. A part of the monomers is incorporated in a monomer charge before polymerization, and the remainder thereof is added in a polymerization mixture during polymerization. The alkylthiol compound has 12 to 16 carbon atoms, which include at least three tertiary carbon atoms, and further has a sulfur atom directly bound to at least one of the tertiary carbon atoms. The copolymer has a Mooney viscosity of 15 to 450 and a bound nitrile content of 10 to 60% by weight. The breadth (.DELTA.AN) of compositional distribution of the unsaturated nitrile in the copolymer is 3 to 20. The copolymer is used in combination with a sulfur-containing vulcanizer.

Abstract: An unsaturated nitrile-conjugated diene copolymer having at least 0.03 mole, per 100 moles of the monomeric units constituting the molecule, of an alkylthio group having 12 to 16 carbon atoms, which include at least three tertiary carbon atoms, and having a sulfur atom which is directly bound to at least one of the tertiary carbon atoms; said copolymer having a Mooney viscosity of 15 to 65. This copolymer is produced by copolymerizing an unsaturated nitrile and a conjugated diene in the presence of a free-radical initiator by using as a molecular weight modifier an alkylthiol compound having the above-mentioned alkylthio group. The copolymer is used as a rubber composition having incorporated therein a sulfur-containing vulcanizer.

Abstract: Disclosed herein is an adhesive composition comprising (A) 100 parts by weight of at least one rubber component selected from the group consisting of unsaturated nitrile-conjugated diene copolymer rubbers prepared by an aqueous suspension polymerization, containing 10-45 wt. % of unsaturated nitrile units in their polymer chains and having a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 30-100, and hydrogenated unsaturated nitrile-conjugated diene copolymer rubbers obtained by hydrogenating at least part of carbon-carbon double bonds in each of the unsaturated nitrile-conjugated diene copolymer rubbers, and (B) 50-500 parts by weight of at least one thermosetting resin selected from the group consisting of phenolic resins and epoxy resins.

Abstract: In an adhesive for printed circuit boards, whose main components are an epoxy resin and a polymer rubber, the improvement wherein the polymer rubber is a hydrogenated conjugated diene polymer rubber having not more than 100 ppm of metal content, not more than 100 ppm of ion content as determined by ion chromatography, and an iodine value of not more than 120, the ratio by weight of the hydrogenated conjugated diene polymer rubber to the epoxy resin in the adhesive being 35-75 weight % to 65-25 weight %.

Abstract: In an adhesive for printed circuit boards, whose main components are an epoxy resin and a polymer rubber, the improvement wherein the polymer rubber is a hydrogenated conjugated diene polymer rubber having not more than 100 ppm of metal content, not more than 100 ppm of ion content as determined by ion chromatography, and an iodine value of not more than 120.

Abstract: An unsaturated nitrile/conjugated diene copolymer rubber is prepared by an aqueous suspension polymerization of a monomer mixture of a conjugated diene monomer, a nitrile group-containing unsaturated monomer and an optional copolymerizable monomer. The suspension polymerization is carried out in an aqueous medium in a reactor provided with an agitating element under the following conditions:(1) the water/monomer mixture weight ratio is from 0.1 to 4,(2) 0.01 to 5 weight parts, per 100 weight parts of the monomer mixture, of a dispersing agent is used, and(3) the agitating element is rotated under conditions such that the speed (U m/sec) of the tip thereof, expressed by the formula: U=.pi..times.D.times.n, is from 1 to 20, wherein D is diameter (m) of the rotation circle of the agitating element and n is number of revolutions (per second) of the agitating element.

Abstract: In a process for producing a conjugated diene copolymer, the improvement in which when copolymerizing a conjugated diene monomer with an ethylenically unsaturated nitrile monomer, at least one compound selected from a bifunctional peroxide represented by formulaR.sub.1 --OO--R.sub.2 --OO--R.sub.3 (I)wherein R.sub.1, R.sub.2 and R.sub.3 each denote a hydrocarbon group, anda bifunctional peroxycarbonate represented by formula ##STR1## wherein R.sub.4, R.sub.5 and R.sub.6 each denote a hydrocarbon group, said bifunctional peroxide and peroxycarbonate being soluble in said monomers, is used as a polymerization initiator.