Process and apparatus for impregnating microporous films and the product produced thereby

Abstract From the Canadian patent

There is disclosed a novel process for coating or impregnating a film of a blend of a thermoplastic orientable polymer with an incompatible polymer and inorganic material/ or a polymer matrix having an inorganic filler followed by the selective stretching in a station provided with a set of grooved rollers to form an opaque, low density, porous film. The group pattern of the rolls are generally of a sinosoidal wave wherein the coated or impregnated film is stretched in a manner to affect uniform stretching between contact points of the material to produce a material of larger dimension in the direction of stretch. In accordance with a preferred embodiment, there is produced an interleaf for …