Block copolymer compositions and process for the preparation thereof
 A block copolymer composition is provided comprising: PA0 (1) 10-60% by weight of a block copolymer [(A--B).sub.11 ].sub.m --Y.sub.1 PA0 (2) 20-90% by weight of a block copolymer [(A--B).sub.12 ].sub.n --Y.sub.2, and PA0 (3) 0-50% by weight of a block copolymer (A--B.sub.13, in which A represents a vinyl aromatic polymer block having a molecular weight of 10,000-30,000 wherein the vinyl aromatic compound is selected from the group consisting of styrene, alkyl substituted styrene and a vinyl naphtalene, B.sub.1 a conjugated diene polymer block having a molecular weight of 25,000-100,000, B.sub.2 a conjugated diene polymer block having a molecular weight at least 1.2 times as high as that of B.sub.1 wherein the conjugated diene compound of B.sub.1 and B.sub.2 is a conjugated diene having four to eight carbon atoms per molecule, Y.sub.1 and Y.sub.2 respectively represent a halogenated, tetravalent silicon compound and a halogenated, tetravalent stannic compound and 11=1-3, m=2-4, 12=1-6, n=2-4 and 13=1-6. The block copolymer is prepared by the successive steps of (i) polymerizing the vinyl aromatic compound building block A and the conjugated diene compound building block B.sub.1, (ii) adding a halogenated tetravalent silicon compound, (iii) adding and polymerizing the conjugated diene compound building block B.sub.2 and (iv) adding a halogenated tetravalent stannic compound. The block copolymer is particularly useful in adhesive compositions. 
Shell Internationale Research Maatschappij B.V.
C C C C C
C08F C08G C09J C08L C08L
inventional inventional inventional inventional additional
Toshinori Yasuo Takumi, Hisaharu
Sakagami Toyama Miyachi Ito