Abstract: Disclosed is a block copolymer composition for flexographic printing plates, which is capable of providing a flexographic printing plate that has much more excellent wear resistance than conventional flexographic printing plates, while maintaining sufficient rubber elasticity. The block copolymer composition for flexographic printing plates comprises a block copolymer A and a block copolymer B, each of which is an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having a specific structure, wherein a content of the aromatic vinyl monomer unit in the block copolymer A is 41% or more.

Abstract: Disclosed is a block copolymer composition for flexographic printing plates, which is capable of providing a flexographic printing plate that has much more excellent wear resistance than conventional flexographic printing plates, while maintaining sufficient rubber elasticity. The block copolymer composition for flexographic printing plates comprises a block copolymer A and a block copolymer B, each of which is an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having a specific structure, wherein a content of the aromatic vinyl monomer unit in the block copolymer A is 41% or more.

Abstract: The present invention provides a composition which comprises a radial poly(aromatic vinyl)/polyisoprene block copolymer as a major component and which can be used as a more excellent pressure-sensitive ingredient. This composition is obtained by reacting a diblock polymer with a coupling agent having a functionality of 4 or higher in the presence of a coupling accelerator, and it contains (a) 1 to 34% by weight of a diblock polymer, (b) 34 to 99% by weight of a four-branch polymer, and (c) 0 to 50% by weight of a two-branch polymer and/or a three-branch polymer. The poly(aromatic vinyl)/polyisoprene block copolymer contained in the composition has a weight-average molecular weight (Mw) of 260,000 to 500,000, and the poly(aromatic vinyl)/polyisoprene block copolymer has a poly(aromatic vinyl) block content of 5 to 24% by weight.

Abstract: An aromatic vinyl compound-isoprene block copolymer composition comprising (i) 5-50 wt. % a branched copolymer of the formula: (A-B)nX wherein A is a polymer block of an aromatic vinyl monomer, B is a polymer block of isoprene, and X is a residue of a polyfunctional coupling agent, and (ii) 50-95 wt. % of a diblock copolymer of the formula: A-B wherein A and B are as defined above. This copolymer composition is produced by allowing an aromatic vinyl monomer to contact with an organic lithium initiator to prepare a polymer block A; incorporating isoprene thereto to prepare a diblock copolymer A-B; and then, adding a polyfunctional coupling agent to convert a part of the diblock copolymer A-B to the branched copolymer (A-B)nX. This block copolymer composition is useful for an adhesive or pressure sensitive adhesive composition.