Removable pressure-sensitive adhesive tape

Claim 1

Pressure-sensitive adhesive tape comprising a self-substaining backing sheet carrying a layer of pressure-sensitive adhesive comprising a copolymer of monomers comprising (a) from 95 to 99.8 parts by weight of at least one terminally unsaturated vinyl monomer, 60 to 100 weight percent of said monomer being selected from the class of nontertiary alkyl acrylates wherein each alkyl group has at least half of its carbon atoms in a single chain and the average length of the alkyl chain is at least 4 and not more than 12, and (b) from 0.2 to 5 parts by weight of at least one vinyl-unsaturated homopolymerizable emulsifier monomer which is a surfactant having both a hydrophobic and a hydrophilic moiety, contains at least 5 but no more than 40 carbon atoms, and is water-dispersible, the total parts by weight (a) plus (b) being 100, wherein the improvement comprises: the emulsifer monomer is a monovalent salt of a styrene sulfonate and wherein the adhesive layer contains up to 1.5% external emulsifier by weight, whereby the tape not only has an adhesive value of at least about 40 N/dm and a cohesive value of at least 100 minutes but also can be cleanly removed from a melamine test surface after one hour at 150? C.