Abstract: A pressure sensitive adhesive sheet comprising a substrate and an adhesive composition which is coated on the surface of the substrate. The main components of the adhesive composition are (a) a copolymer comprising monomeric units of an acrylic ester, (b) monomeric units of a polar acrylic compound, (c) monomeric units of a high glass transition temperature (Tg) macromonomer having a Tg of 20.degree. C. or above, (d) monomeric units of a low Tg macromonomer having a Tg of below 20.degree. C. and (e) monomeric units of an oligomer having telechelic thiol functional groups. The pressure sensitive adhesive sheet has excellent adhesive strength, resistance against formation of blisters and removability upon heating.

Abstract: The pressure-sensitive adhesive sheet of the invention is free from the troubles of forming blisters due to the gas emission from the substrate surface to which the adhesive sheet is applied and bonded by using a unique pressure-sensitive adhesive to form the adhesive layer on a base sheet. The principal ingredient of the pressure-sensitive adhesive used in the present invention is a copolymer having a specified molecular weight and a specified glass transition temperature and composed of (a) from 50 to 85% by weight of a first monomeric moiety of an acrylic ester, e.g., 2-ethylhexyl acrylate, (b) from 1 to 30% by weight of a second monomeric moiety of an acrylic compound having a polar group, e.g., acrylic acid, and (c) from 5 to 40% by weight of a third monomeric moiety of a macromonomer having a polymeric molecular chain of styrene units and/or methyl methacrylate units and having a polymerizable functional group, e.g., methacryloyl group, at the molecular chain end.