Thermoplastic resin composition

Claim 1

A resin composition consisting essentially of a. a styrene-butadiene block copolymer resin represented by the formula, A.sub.1 -- B.sub.1 -- C -- B.sub.2 -- A.sub.2 wherein A 1 and A 2 are non-elastomeric blocks comprising a styrene polymer chain; B 1 and B 2 are elastomeric blocks comprising a random copolymer chain in which styrene and butadiene have uniformly been distributed; C is an elastomeric block comprising a butadiene homopolymer chain or a styrene-butadiene copolymer chain; the proportion of the sum of A 1 and A 2 in the block copolymer is 40 to 80 weight %; the proportion of the sum of B 1 and B 2 in the block copolymer is 10 to 60 weight %; the proportion of C in the block copolymer is 0 to 25 weight % and is always smaller than the proportion of the sum of B 1 and B 2 ; the weight ratio of A 1 to A 2 is in the range from 2:8 to 8:2; the weight ratio of B 1 to B 2 is in the range from 0:10 to 10:0; the weight ratio of styrene to butadiene in B 1 and B 2 is in the range from 10:90 to 75:25; and the weight ratio of styrene to butadiene in C is in the range from 0:100 to 10:90, b. a resin selected from the group consisting of a liquid polybutadiene, a liquid butadiene-styrene copolymer, a maleic anhydride-modified liquid polybutadiene and an epoxidation-modified liquid polybutadiene, and c. a tackifier, wherein the contents of (a) the styrene-butadiene block copolymer, (b) the resin, and (c) the tackifier are 70 to 94 weight %, 3 to 15 weight % and 3 to 15 weight %, respectively.