Patent ID: 8480836

Claim:
A method of making a double-sided cloth-like film having a rough, slip-resistant, open-celled outer surface, said method comprising the following steps: using a film blowing machine to coextrude a multilayer film from a circular die to form a tube having first and second sides, wherein the tube comprises at least three coextruded layers of film including an inner layer, an outer layer, and a middle layer, said inner layer comprising a thermoplastic heat sealable material having a predetermined softening point, wherein said outer layer comprises a plurality of gas bubbles resulting from addition of a blowing agent to its film making material provided to said circular die, said blowing agent causing said gas bubbles to form in said outer layer as said outer layer is coextruded from the circular die, and wherein each of said first and second sides of said tube include said at least three layers; drawing the resulting coextruded multilayer film tube away from the circular die at a predetermined speed; at a predetermined distance from the circular die, collapsing the coextruded multilayer film tube during said drawing by passing the film tube between at least two rollers positioned in close proximity to one another so that a first roller of said at least two rollers contacts said first side of the coextruded multilayer film tube and so that a second roller of said at least two rollers contacts said second side of said coextruded multilayer film tube, wherein said first roller is a metal nip roller heated to a temperature at or above the predetermined softening point of said heat sealable inner layer, said temperature sufficient to cause fusing of the inner layer of the first side with the inner layer of the second side, thereby causing the first and second sides of the coextruded multilayer film tube to fuse into a double-sided film, and wherein said second roller is a rubber roller; passing the resulting fused double-sided film through a pair of heated in-line rollers, wherein at least one of said pair of heated in-line rollers is heated to a temperature above the glass transition temperature of said heat sealable inner layer, said pair of heated in-line rollers rotating at approximately the same speed as said predetermined speed at which the coextruded multilayer film tube is drawn from the circular die; and subsequent to passing the fused double-sided film through said pair of heated in-line rollers, passing the fused double-sided film through a pair of cooled in-line rollers rotating faster than said pair of heated in-line rollers to thereby cause the fused double-sided film to stretch in at least one direction, wherein at least one of said pair of cooled in-line rollers is operated at a temperature cooler than the predetermined softening point of said heat sealable inner layer, and wherein said plurality of gas bubbles are collapsed by said stretching and cooling, thereby forming said double-sided cloth-like film.