Energy-curable acrylic pressure-sensitive adhesives

A cured pressure-sensitive adhesive comprising a copolymer formed of:

• at least one interpolymerized first monomer having a glass-transition temperature less than about 25.degree. C. and an entanglement molecular-weight, said first monomer being selected from the group consisting of 2-ethylhexyl acrylate, butyl acrylate and 2-methylbutyl acrylate greater than about 20,000 and present in an amount of from about 55% to about 90% by weight based on the total weight of the monomers;
• at least one interpolymerized second monomer having a glass-transition temperature greater than about -25.degree. C. and an entanglement molecular-weight less than about 20,000 said second monomer being an unsaturated carboxylic acid and present in an amount up to about 25% by weight based on the total weight of the monomers;
• and
• at least one interpolymerized tackifier monomer having a glass-transition temperature greater than -25.degree. C. and an entanglement molecular-weight of at least about 20,000, said tackifying monomer being a lower alkyl diester of an unsaturated dicarboxylic acid containing 4 carbon atoms and in which each alkyl group contains from 1 to 3 carbon atoms and present in an interpolymerized amount sufficient to form an interpolymer having a glass-transition temperature less than about -25.degree. C. and an entanglement molecular-weight greater than about 20,000;
• and wherein the pressure-sensitive adhesive is a hot-melt applied and radiation cross-linked after application in the presence of a multifunctional monomer selected from the group consisting of pentaerythritol triacrylate, tetraethylene glycol dimethacrylate and trimethylol propane trimethacrylate.