Acrylate copolymer pressure-sensitive adhesive composition and sheet materials coated therewith

Claim 1

A normally tacky and pressure-sensitive adhesive composition comprising copolymer having an inherent viscosity greater than 0.2 and consisting essentially of copolymerized repeating A and C monomers and optionally B monomers, wherein A is a monomeric acrylic or methacrylic acid ester of a non-tertiary alcohol, said alcohol having from 1 to 14 carbon atoms with the average number of carbon atoms being about 4-12; when used, B is at least one polar monomer copolymerizable with said monomeric acrylic acid ester, the amount by weight of B monomer being up to 12% of the total weight of all monomers; and C is a monomer having the general formula X--(Y) n --Z wherein X is a vinyl group copolymerizable with said A and B monomers; Y is a divalent linking group; where n can be zero or 1; Z is a monovalent polymeric moiety having a T g greater than 20° C. and a molecular weight in the range of about 2,000 to 30,000 and being essentially unreactive under copolymerization conditions; wherein said vinyl group and said A and B monomers are copolymerized to form a soft polymeric backbone having pendant therefrom said polymeric moieties and wherein the weight of said C monomer is within the range of about 1 to 30% of the total weight of all monomers in said copolymer and the total weight of said B and C monomers in said copolymer is within the range of about 4 to 30% of the total weight of all monomers in said copolymer, the amount of said C monomer in said polymer is such as to provide said adhesive composition with a shear holding value of at least 50 minutes.