| 摘要 |
A method of rendering a flexible hydrophobic backing film of cellulose acetate-propionate or cellulose acetate-butyrate, to which pressure-sensitive film adhesives ordinarily adhere poorly, capable of forming firmly adherent bonds with a subsequently applied pressure-sensitive adhesive, includes the steps of preparing an aqueous emulsion of a polymeric alkyl acrylate, which is capable of forming a substantially tackfree film, and a rubbery material which is compatible with the pressure-sensitive adhesive which it is desired to employ, uniformly applying the emulsion on a major surface of the backing film, and heating the thus coated film, e.g. to a temperature of 170 DEG F. (77 DEG C.), for a time sufficient to evaporate the water and anchor the primer coating to the film. A pressure-sensitive adhesive is applied over the primed film. The alkyl acrylate polymer (which term includes alkyl methacrylate polymers) may be non-tacky and derived from an alcohol containing not more than four carbon atoms. The aqueous emulsion may comprise polymers of alkyl acrylates or alkyl methacrylates, or copolymers thereof with vinyl acetate or chloride, acrylic or methacrylic acid, itaconic acid or maleic anhydride, and a soft, readily deformable rubber of the same type as that contained in the pressure-sensitive adhesive, the weight ratio of alkyl acrylate polymer to rubber in the primer layer being in the range of from 0,5 : 1 to 2 : 1. The primer layer may comprise from at least 0,02, e.g. 0,2-10, parts by weight of an alkyl acrylate polymer derived from an alcohol containing not more than four carbon atoms and one part by weight of a soft readily deformable rubber, e.g. a normally tacky acrylate polymer which is compatible with the pressure-sensitive adhesive. The pressure-sensitive adhesive sheet material is capable of being wound in roll form and unwound therefrom in normal use. The rubbery material may be natural rubber, butadiene-styrene copolymer, polyisobutylene or butyl rubber. The adhesive specified contains natural rubber and terpene resin. |
