Styrene copolymer composition

A block copolymer having a block configuration comprising (A) at least two polymer blocks each comprised mainly of vinyl aromatic hydrocarbon monomer units and (B) at least one vinyl aromatic hydrocarbon/isoprene/1,3-butadiene copolymer block having an isoprene monomer unit/1,3-butadiene monomer unit weight ratio in the range of from 5/11 to 3/5,

• said block copolymer comprising 65 to 90% by weight of vinyl aromatic hydrocarbon monomer units and 35 to 10% by weight of conjugated diene monomer units comprising isoprene monomer units and 1,3-butadiene monomer units, said block copolymer having an isoprene monomer unit/1,3-butadiene monomer unit weight ratio in the range of from 7/25 to 13/11,
• wherein the vinyl aromatic hydrocarbon monomer unit moiety of said block copolymer has a short segment ratio of from 1 to 25% by weight, wherein said short segment ratio is defined as the weight percentage, based on the total weight of vinyl aromatic hydrocarbon monomer units contained in said block copolymer, of the vinyl aromatic hydrocarbon monomer units contained in at least one short segment consisting of 1 to 3 vinyl aromatic hydrocarbon monomer units,
• wherein said at least two polymer blocks (A) contain a maximum peak molecular weight polymer block exhibiting a maximum peak molecular weight in a gel permeation chromatogram of said at least two polymer blocks (A) and having at least one peak molecular weight in the range of from 30,000 to 150,000, and the content of said maximum peak molecular weight polymer block in said at least two polymer blocks (A) is from 20 to 50% by weight, and
• wherein said at least two polymer blocks (A) have a maximum weight polymer block and a minimum weight polymer block, wherein the weight ratio of said maximum weight polymer block to said minimum weight polymer block is from 1.2 to 4.5.

A styrene copolymer composition comprising:

• (I) a styrene/n-butyl acrylate copolymer comprising 80 to 89% by weight of styrene monomer units and 20 to 11% by weight of n-butyl acrylate monomer units;
• and
• (II) a block copolymer having a block configuration comprising (A) at least two polymer blocks each comprised mainly of vinyl aromatic hydrocarbon monomer units and (B) at least one vinyl aromatic hydrocarbon/conjugated diene copolymer block,
• said block copolymer (II) comprising 75 to 85% by weight of vinyl aromatic hydrocarbon monomer units and 25 to 15% by weight of conjugated diene monomer units,
• wherein the vinyl aromatic hydrocarbon monomer unit moiety of said block copolymer (II) has a short segment ratio of from 10 to 20% by weight, wherein said short segment ratio is defined as the weight percentage, based on the total weight of vinyl aromatic hydrocarbon monomer units contained in said block copolymer (II), of the vinyl aromatic hydrocarbon monomer units contained in at least one short segment consisting of 1 to 3 vinyl aromatic hydrocarbon monomer units,
• wherein said at least two polymer blocks (A) contain a peak molecular weight-having polymer block exhibiting, in a gel permeation chromatogram of said at least two polymer blocks (A), at least one peak molecular weight in the range of from 20,000 to 70,000, and the content of said peak molecular weight-having polymer block in said at least two polymer blocks (A) is from 25 to 35% by weight,
• wherein said at least two polymer blocks (A) have a maximum weight polymer block and a minimum weight polymer block, wherein the weight ratio of said maximum weight polymer block to said minimum weight polymer block is from 1.0 to less than 1.2, and
• wherein the weight ratio of said styrene/n-butyl acrylate copolymer (I) to said block copolymer (II) is from 20/80 to 60/40.

A block copolymer having a block configuration comprising (A) at least two polymer blocks each comprised mainly of vinyl aromatic hydrocarbon monomer units and (B) at least one vinyl aromatic hydrocarbon/isoprene/1,3-butadiene copolymer block,

• said block copolymer comprising 75 to 85% by weight of vinyl aromatic hydrocarbon monomer units and 25 to 15% by weight of conjugated diene monomer units comprising isoprene monomer units and 1,3-butadiene monomer units, said block copolymer having an isoprene monomer unit/1,3-butadiene monomer unit weight ratio in the range of from 7/18 to 6/11,
• wherein the vinyl aromatic hydrocarbon monomer unit moiety of said block copolymer has a short segment ratio of from 10 to 20% by weight, wherein said short segment ratio is defined as the weight percentage, based on the total weight of vinyl aromatic hydrocarbon monomer units contained in said block copolymer, of the vinyl aromatic hydrocarbon monomer units contained in at least one short segment consisting of 1 to 3 vinyl aromatic hydrocarbon monomer units,
• wherein said at least two polymer blocks (A) contain a peak molecular weight-having polymer block exhibiting, in a gel permeation chromatogram of said at least two polymer blocks (A), at least one peak molecular weight in the range of from 20,000 to 70,000, and the content of said peak molecular weight-having polymer block in said at least two polymer blocks (A) is from 25 to 35% by weight, and
• wherein said at least two polymer blocks (A) have a maximum weight polymer block and a minimum weight polymer block, wherein the weight ratio of said maximum weight polymer block to said minimum weight polymer block is from 1.0 to less than 1.2.