Self-adhered single-sided slip-resistant material

A method of making single-sided, anti-slip film layers, each anti-slip film payer having a rough, slip-resistant, open-celled outer surface on one film side thereof, said method comprising the following acts:

• using a film blowing machine to vertically 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 outer layer comprising a plurality of gas bubbles resulting from addition of a blowing agent to its film making material provided to said circular die, and said blowing agent causing said gas bubbles to form in said outer layer as said outer layer is coextruded from said circular die;
• drawing the resulting coextruded multilayer film tube vertically and upwardly 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 said 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 first and second sides of the inner layer of said film tube abut one another without fusing or sticking together as a result of said collapsing, wherein surfaces of said rollers contacting said first and second sides of said film are parallel to one another, said collapsed, co-extruded, multi-layer film having first and second edges;
• and
• cutting the multi-layer film proximate said first and second edges to form two generally identical, single-sided film layers each with an inner surface and a non-slip outer surface.