Importance

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Abstract

A process for preparing composite films comprising at least one layer of a first plastic polymer and a substrate of a second polymer/first plastic polymer composition by intimately mixing about 15 to about 90 wt. % of first plastic polymer and about 10 to 85 wt. % of the second polymer, extruding the mixture through a film die while cooling at least one surface of the die outlet at least about 10.degree. C. below the melting point of the plastic polymer and cooling the film. In a preferred embodiment the first plastic polymer has a semi-crystalline or crystalline melting point which is at least 10.degree. C. above the softening or melting point of the second polymer. A sandwich type laminate comprising two outer skins of first plastic polymer enclosing a core comprising a blend of first plastic polymer and second polymer can be prepared by cooling both die outlet surfaces. Where a blown film die is utilized the inner and outer die layers must be cooled to accomplish this end. In a sheet die both the upper and lower die layers are cooled.

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First Claim