Hot-melt pressure-sensitive adhesive composition containing an acid grafted block copolymer

Claim 1

A hot-melt pressure-sensitive adhesive composition comprising: (a) 100 parts by weight of a grafted block copolymer material formed by the graft reaction of at least one block copolymer with at least one unsaturated carboxylic acid monomer and/or derivative monomer thereof in an amount of 0.01 to 30% by weight based on the total of said at least one block copolymer and said at least one monomer, said at least one block copolymer being represented by the following formula: A--B--A, (A--B).sub.n, B--A--B).sub.n, (A--B).sub.n A or (A--B).sub.m X wherein B stands for a block consisting essentially of butadiene or isoprene monomer units, A stands for a block consisting essentially of styrene monomer units, n is an integer of from 2 to 10, X is the residue of a polyfunctional coupling agent to which m of (A--B) are bonded and m is an integer of from 2 to 7, having a melt flow index of 0.1 to 40 g/10 minutes as measured in accordance with ASTM D 1238 (Condition G), and containing 5 to 50% by weight of styrene monomer units; and (b) 50 to 250 parts by weight of a tackifier mixture consisting of a tackifier S and a tackifier L and having an S/L mixing weight ratio of 9/1 to 3/7, said tackifier S being at least one terpene resin having a softening point of 60° C. or more or a mixture of 50% by weight or more of at least one terpene resin having a softening point of 60° C. or more and less than 50% by weight of at least one other resin having a softening point of 60° C. or more and selected from rosin and derivatives thereof, petroleum resins and styrene resins, and said tackifier L being at least one terpene resin having a softening point of 30° C. or less or a mixture of 50% by weight or more of at least one terpene resin having a softening point of 30° C. or less and at least one other resin having a softening point of 30° C. or less and selected from rosin derivatives, petroleum resins and styrene resins.