A block copolymer consists mainly of structural units each derived from an ethylenically unsaturated monomer and has at least one mercapto group. The block copolymer has an Mn of 5,000-500,000 and has a block structure, which is an A-B-A triblock structure or a star-shaped block structure of [A-B]qX. The q is an integer of 2-6. The polymer block (A) has a glass transition temperature of 20° C. or higher. The polymer block (B) of the triblock structure has a glass transition temperature lower than 20° C., and the [polymer block (B)]qX of the star-shaped block structure has a glass transition temperature lower than 20° C. The X is an initiator residue or/and a coupling-agent residue or is a derivative thereof.

A block copolymer consists mainly of structural units each derived from an ethylenically unsaturated monomer and has at least one mercapto group. The block copolymer has an Mn of 5,000-500,000 and has a block structure, which is an A-B-A triblock structure or a star-shaped block structure of [A-B]qX. The q is an integer of 2-6. The polymer block (A) has a glass transition temperature of 20° C. or higher. The polymer block (B) of the triblock structure has a glass transition temperature lower than 20° C., and the [polymer block (B)]qX of the star-shaped block structure has a glass transition temperature lower than 20° C. The X is an initiator residue or/and a coupling-agent residue or is a derivative thereof.

A block copolymer consists mainly of structural units each derived from an ethylenically unsaturated monomer and has at least one mercapto group. The block copolymer has an Mn of 5,000-500,000 and has a block structure, which is an A-B-A triblock structure or a star-shaped block structure of [A-B]qX. The q is an integer of 2-6. The polymer block (A) has a glass transition temperature of 20° C. or higher. The polymer block (B) of the triblock structure has a glass transition temperature lower than 20° C., and the [polymer block (B)]qX of the star-shaped block structure has a glass transition temperature lower than 20° C. The X is an initiator residue or/and a coupling-agent residue or is a derivative thereof.

A chloroprene-based block copolymer latex, including a chloroprene-based block copolymer, wherein: the chloroprene-based block copolymer contains 5 to 30% by mass of a polymer block (A) and 70 to 95% by mass of a chloroprene-based polymer block (B); the polymer block (A) is derived from a monomer; when the monomer is polymerized alone, a polymer with a glass transition temperature of 80° C. or higher can be obtained; the chloroprene-based polymer block (B) includes a chloroprene monomer unit; and when the chloroprene-based block copolymer latex is molded by immersion molding to obtain a film and then the film is heat-treated at 130° C. for 30 minutes, a tensile strength at break measured in accordance with JIS K6251 of the film is 17 MPa or more is provided.

A chloroprene-based block copolymer latex, including a chloroprene-based block copolymer, wherein: the chloroprene-based block copolymer contains 5 to 30% by mass of a polymer block (A) and 70 to 95% by mass of a chloroprene-based polymer block (B); the polymer block (A) is derived from a monomer; when the monomer is polymerized alone, a polymer with a glass transition temperature of 80° C. or higher can be obtained; the chloroprene-based polymer block (B) includes a chloroprene monomer unit; and when the chloroprene-based block copolymer latex is molded by immersion molding to obtain a film and then the film is heat-treated at 130° C. for 30 minutes, a tensile strength at break measured in accordance with JIS K6251 of the film is 17 MPa or more is provided.

The invention relates to a block copolymer comprising at least one rigid polyamide block and at least one flexible block, characterized in that the flexible block has an NH.sub.2/OH ratio of concentrations of amine chain ends to alcohol chain ends which is within the range from 30 to 150, said concentrations being measured by .sup.1H NMR (TF.sub.anh./CD.sub.2Cl.sub.2.sup.3). The invention also relates to the use of a flexible block for manufacturing a copolymer containing polyamide blocks and flexible blocks that is both hydrolysis-resistant and CO.sub.2-permeable, with a permeability to CO.sub.2 of at least 10 000 cm.sup.3/m.sup.2/24 h/atm for a 25 μm film of said copolymer, characterized in that said flexible block has a ratio of amine chain ends to acid chain ends which is within the range from 30 to 150.

The invention relates to a block copolymer comprising at least one rigid polyamide block and at least one flexible block, characterized in that the flexible block has an NH.sub.2/OH ratio of concentrations of amine chain ends to alcohol chain ends which is within the range from 30 to 150, said concentrations being measured by .sup.1H NMR (TF.sub.anh./CD.sub.2Cl.sub.2.sup.3). The invention also relates to the use of a flexible block for manufacturing a copolymer containing polyamide blocks and flexible blocks that is both hydrolysis-resistant and CO.sub.2-permeable, with a permeability to CO.sub.2 of at least 10 000 cm.sup.3/m.sup.2/24 h/atm for a 25 μm film of said copolymer, characterized in that said flexible block has a ratio of amine chain ends to acid chain ends which is within the range from 30 to 150.

Provided is a block copolymer with an acid group that, when used as a dispersant, can provide a dispersion composition having excellent dispersion stability, a dispersant containing the block copolymer, and a pigment dispersion composition using the dispersant. The block copolymer is an ABA block copolymer including an A block and a B block and has the feature that its acid value is 30 to 250 mgKOH/g and the B block contains a structural unit derived from a vinyl monomer with an acid group.

A catalyst composition, a method for hydrogenating styrenic block copolymer employing the same, and a hydrogenated polymer from the method are provided. The method for hydrogenating styrenic block copolymer includes subjecting a hydrogenation process to a styrenic block copolymer in the presence of a catalyst composition. In particular, the catalyst composition includes an oxide carrier, and a catalyst disposed on the oxide carrier, wherein the catalyst includes a platinum-and-rhenium containing phosphorus compound.

A catalyst composition, a method for hydrogenating styrenic block copolymer employing the same, and a hydrogenated polymer from the method are provided. The method for hydrogenating styrenic block copolymer includes subjecting a hydrogenation process to a styrenic block copolymer in the presence of a catalyst composition. In particular, the catalyst composition includes an oxide carrier, and a catalyst disposed on the oxide carrier, wherein the catalyst includes a platinum-and-rhenium containing phosphorus compound.