Patent ID: 6998446

Claim:
An unbalanced multi-block SBS copolymer with the following structure, mB1*S1−lB2−S2−sB3, wherein B is a butadiene block, S is a styrene block, l, m, s are relative size among the blocks, wherein l>m>s, and * is the tapered block between mB1 block and S1 block, and they also have to satisfy the following related expressions: 0.01lB2≦mB1≦0.5lB2and 0.01mB1≦sB3≦0.5mB1 a) 0.5S1≦S2≦1.5S1 b) 5%≦*%≦25% c) In the related expressions, the value of B1 and S1 include tapered block, and *% means the random styrene content in all the styrene in SBS.