Plastic skin envelopes for glass bottles and the like

Claim 1

A method of producing a seamless lightweight, strong, uniform, multi-ply, oriented foamed layer tubular laminate preform with good opacity adapted to be heat-shrunk onto a tubular substrate rapidly and uniformly, which comprises co-extruding through coaxial annular dies a first and second plastic material, said first plastic material comprising a low density polyethylene and said second plastic comprising an intimate mixture of an ethylene polymer and 0.1%-2% of a blowing agent having a decomposition range above the softening point of the ethylene polymer and below the decomposition temperature of the ethylene polymer, drawing down the resultant tubular foamed laminate at a speed of about 10-25 feet/minute; inflating said tubular foamed laminate wherein the blow-up ratio is about 1:1 to 3:1 such that shrinkage in the machine direction upon application of heat to the resulting laminate will be about 70%-90% and shrinkage in the transverse direction will be about 5%-15%; cooling said foamed tubular laminate and cutting said laminate to length to form said tubular preform and wherein the non-foamed ply of said final laminated preform is about 10%-20% of the thickness thereof.

Claim 2

A method of producing a seamless lightweight, strong, uniform, multi-ply, oriented foamed layer tubular laminate preform with good opacity adapted to be heat-shrunk onto a tubular substrate rapidly and uniformly, which comprises co-extruding through coaxial annular dies a first and second plastic material, said first plastic material comprising a low density polyethylene and said second plastic comprising an intimate mixture of an ethylene polymer and 0.1%-2% of a blowing agent having a decomposition range above the softening point of the ethylene polymer and below the decomposition temperature of the ethylene polymer, drawing down the resultant tubular foamed laminate at a speed of about 10-25 feet/minute; inflating said tubular foamed laminate wherein the blow-up ratio is about 1:1 to 3:1 such that shrinkage in the machine direction upon application of heat to the resulting laminate will be about 70%-90% and shrinkage in the transverse direction will be about 5%-15%; cooling said foamed tubular laminate and cutting said laminate to length to form said tubular preform and wherein the non-foamed ply of said final laminated preform is about 10%-20% of the thickness thereof.