| abstract |
Release coatings are provided by including in a liquid monomer or prepolymer polymerizable by electromagnetic or ionizing radiation a waxy material of limited compatibility therein. Upon application of a film of such material by casting, coating or printing, a thin layer of the waxy material migrates to the surface to provide, after cure, the desired release properties. The thin surface layer of waxy material also tends to exclude oxygen from the film to permit radiant curing in air. Preferably the polymerizable liquid comprises acrylate monomers with or without unsaturated prepolymers co-polymerizable therewith dissolved therein. Novel prepolymers especially useful for providing release films and other radiation curable coatings are described, including the reaction product of polyamine containing polyamides with unsaturated polybasic carboxylic acids and particular reaction products of polyether triols with toluene diisocyanate, modified with unsaturated monomers. Also described is the inclusion in the polymerizable liquid of a dispersed substantially linear polymer as shrink control and re-inforcing agent. |