A disclosed crosslinkable rubber composition includes a carboxyl group-containing nitrile rubber (A) containing a halogen or a halogen compound, and having an iodine value of 120 or less; a polyamine-based crosslinking agent (B); and a metal-based acid acceptor (C).

Disclosed is a block copolymer including one or more blocks of an acrylate polymer and one or more blocks of a chloroprene polymer, wherein the number average molecular weight of the block copolymer is 110,000 or more, the number average molecular weight of the block of a chloroprene polymer is 80,000 or more in total, and the block copolymer has a functional group with a structure represented by the following chemical formula (1) or (2):

##STR00001##

wherein in the chemical formula (1), R.sup.1 represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group or a substituted, or unsubstituted heterocyclyl group.

To provide a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit which has a satisfactory oil resistance. A method for producing a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit includes a step for conducting continuous addition or 10 cycles or more of intermittent portionwise addition of the chloroprene monomer after initiation of a polymerization reaction is provided. A rubber composition using a statistical copolymer according to the invention or a vulcanized molded article containing the rubber composition is excellent in terms of oil resistance, mechanical strength, compression set at a low temperature and flex fatigue resistance.

To provide a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit which has a satisfactory oil resistance. A method for producing a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit includes a step for conducting continuous addition or 10 cycles or more of intermittent portionwise addition of the chloroprene monomer after initiation of a polymerization reaction is provided. A rubber composition using a statistical copolymer according to the invention or a vulcanized molded article containing the rubber composition is excellent in terms of oil resistance, mechanical strength, compression set at a low temperature and flex fatigue resistance.

Provided is a chloroprene rubber latex adhesive composition superior in initial adhesive strength and normal adhesive strength and also in thermal creep resistance with adherend. A chloroprene rubber latex adhesive composition includes a carboxy-modified chloroprene-based copolymer latex (A) containing a copolymer of chloroprene monomer and an ethylenic unsaturated carboxylic acid and a polyvinylalcohol, a chloroprene-based polymer latex (B) containing a chloroprene homopolymer or a copolymer of chloroprene monomer and other monomer and a rosin acid metal salt and a chlorinated polyolefin resin emulsion (C), wherein the content ratio of the carboxy-modified chloroprene-based copolymer latex (A) to the chloroprene-based polymer latex (B) is 80:20 to 20:80 as solid matter.

To provide a block copolymer that includes an aromatic vinyl compound polymer and a chloroprene polymer, has a number average molecular weight of 100,000 or more, is preferred for a rubber composition and an adhesive composition, and is suitable for industrial production. A block copolymer includes at least one aromatic vinyl compound polymer block and at least one chloroprene polymer block, has a functional group with a structure represented by Chemical Formula (1) or (2), and has a number average molecular weight of 100,000 or more. The chloroprene polymer block has a number average molecular weight of 80,000 or more in total.

##STR00001##

(In Chemical Formula (1), R.sup.1 is hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclyl group)

To provide a block copolymer that includes an aromatic vinyl compound polymer and a chloroprene polymer, has a number average molecular weight of 100,000 or more, is preferred for a rubber composition and an adhesive composition, and is suitable for industrial production. A block copolymer includes at least one aromatic vinyl compound polymer block and at least one chloroprene polymer block, has a functional group with a structure represented by Chemical Formula (1) or (2), and has a number average molecular weight of 100,000 or more. The chloroprene polymer block has a number average molecular weight of 80,000 or more in total.

##STR00001##

(In Chemical Formula (1), R.sup.1 is hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclyl group)

A method for producing a chloroprene-based polymer latex which can efficiently remove a residual volatile organic substance from the chloroprene-based polymer latex while suppressing the deposition of agglomerates is provided. In the method for producing a chloroprene-based polymer latex of the present invention, when the residual volatile organic substance comprised in the latex is volatilized and removed, a mixed fluid of one or more gases selected from the group consisting of inert gases and air, and water is contacted with the latex at a gas pressure higher than the saturated water vapor pressure, and a temperature of the mixed fluid is a temperature lower than a boiling point of water at the gas pressure.

A method for producing a chloroprene-based polymer latex which can efficiently remove a residual volatile organic substance from the chloroprene-based polymer latex while suppressing the deposition of agglomerates is provided. In the method for producing a chloroprene-based polymer latex of the present invention, when the residual volatile organic substance comprised in the latex is volatilized and removed, a mixed fluid of one or more gases selected from the group consisting of inert gases and air, and water is contacted with the latex at a gas pressure higher than the saturated water vapor pressure, and a temperature of the mixed fluid is a temperature lower than a boiling point of water at the gas pressure.

A chloroprene-unsaturated nitrile copolymer composition containing 100 parts by mass of a chloroprene-unsaturated nitrile copolymer having 3 to 20% by mass of a structural unit derived from an unsaturated nitrile monomer, and 0.05 to 2.0 parts by mass of a xanthogen compound.