Contamination-tolerant pressure-sensitive adhesive tape

Claim 1

Pressure-sensitive tape comprising a sheet backing coated with a layer of normally tacky and pressure-sensitive adhesive which is not only capable of maintaining useful bonding properties even after its surface has been contaminated with talc but which also has good shear adhesion, a force of at least 15 grams per centimeter width being required to remove said pressure-sensitive tape from a talc-contaminated polyethylene film, said adhesive consisting essentially of a blend of 100 parts by weight of (a) 5-25 parts by weight of a rubbery synthetic block copolymer selected from the class consisting of: (1) A-B, A-B-A or blends of A-B and A-B-A wherein A is a polymer of styrene and B is selected from the class consisting of homopolymers of isoprene and copolymers of ethylene and butylene and (2) radial or teleblock copolymer consisting of several polystyrene-terminated elastomeric branches, each of said branches being a homopolymer of isoprene extending from a central hub; (b) 15-50 parts by weight of polyterpene-type tackifier resin which is solid at room temperature; and (c) 40-75 parts by weight of a polyterpene-type tackifier resin which is liquid at room temperature.