| 摘要 |
A block terpolymer for use in photocurable compositions, flexographic printing plates or hot melt adhesives having a molecular structure according to the general formula: A-I-B-I-A  (1) or (A-I-B)n-X  (2), wherein each A is independently a polymer block of predominantly an aromatic vinyl compound, each I is predominantly isoprene, each B is predominantly butadiene, n is an integer equal to or greater than 2, and X is the residue of a coupling agent, and wherein: (a) the weight ratio of I to B is in a range of 30:70 to 70:30; (b) the aromatic vinyl compound content of the block copolymer is from about 14 to about 45%; (c) the B block has a 1,2-vinyl bond content in the range of from about 20 to about 90 mol %; (d) the A block has an apparent molecular weight in the range of from about 5,000 to about 20,000, and the I and B blocks together have a molecular weight in the range of from about 50,000 to about 200,000; (e) uncoupled triblock, S-I-B in the range of from about 2% to about 60%.
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