Process for production of embossed films based on plasticized polyvinyl acetal

Abstract

Polyvinyl acetal films with less blocking tendency and which allow for escape of gas during laminating to form laminated composities are prepared by a process for embossing a film comprising plasticized polyvinyl acetal with a roughness Rz on at least one surfaces of 20 to 100 μm by the steps of a. extruding of plasticised polyvinyl acetal to a film with a stochastic roughness of the surfaces of Rz =1 to 70 μm, b. embossing at least one surface of the film obtained in step a) with channels having a depth of 5-50 μm, a width of 10-200 μm and a pitch of 50-2500 μm, wherein c. the surface roughness of the elevations between the channels is at most 20% lower as obtained in step a).

Dependencies are inferred from the claim text.