Adhesive composition
The invention relates to an adhesive composition comprising (i) one or more styrenic block copolymers, (ii) a tackifier resin, and (iii) one or more plasticizers, wherein the or one of the styrenic block copolymers is of the general formulae A-C-A (1), or (A-C) n —X (2), wherein each A independently is a polymer block of an aromatic vinyl compound, and C is a mixed polymer block (B/I) of butadiene (B) and isoprene (I) in a weight ratio B:I in the range of 30:70 to 70:30, and said polymer block C has a glass transition temperature (Tg) of at most −50° C. (determined according to ASTM E-1356-98), n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein the tackifier resin has an aromaticity (in relative percentage of aromatic protons as determined by H-NMR) in the range of from 3 to 18%.
1 . A printing plate comprising one or more styrenic block copolymers of the general formulae
A-C-A or (A-C) n —X,
wherein each A independently is a polymer block of an aromatic vinyl compound, and C is a mixed polymer block (B/I) of butadiene (B) and isoprene (I) in a weight ratio B:I in the range of 30:70 to 70:30, and said polymer block C has a glass transition temperature (Tg) of at most −50° C. (determined according to ASTM E-1356-98), n is an integer equal to or greater than 2, and X is the residue of a coupling agent.
2 . The printing plate of claim 1 wherein said aromatic vinyl compound is styrene.
3 . The printing plate of claim 2 wherein the proportion of bound aromatic vinyl compound is in the range from 10 to 50 weight percent.
4 . The printing plate of claim 3 wherein the proportion of bound butadiene is in the range from 15 to 65 weight percent.
5 . The printing plate of claim 4 wherein the proportion of bound isoprene is in the range from 15 to 65 weight percent.
6 . The printing plate of claim 5 wherein each A polymer block has a true molecular weight in the range of 9,500 to 25,000.
7 . The printing plate of claim 5 wherein the C polymer block has a vinyl content of less than 15 weight percent.
8 . The printing plate of claim 7 wherein the block copolymer has a weight average molecular weight (expressed in terms of polystyrene) in the range of 100,000 to 500,000 (as determined by GPC).
9 . The printing plate of claim 8 wherein component (i) comprises a block copolymer according to the general formulae A-D-A or (A-C)n-X and a diblock copolymer A-B in a weight ratio of block copolymer:diblock in the range of 100/0 to 30/70.