Patent ID: 7442332

Claim:
A method of making thermoplastic film, comprising extruding a thermoplastic extrudate in the form of a web in its molten state, locating a chill roller operating at a peripheral velocity (V 1 ) and at a temperature (T 1 ) to receive and cool said web thereby forming a film, locating a second roller operating at a peripheral velocity (V 2 ) greater than said V 1 to receive said film at a temperature (T 2 ), spacing said second roller from said chill roller to provide a roll gap of no more than one inch between said chill roller and said second roller for stretching said film, uniformly stretching said film in said roll gap at a stretch temperature between said T 1 and T 2 at a speed between said V 1 and V 2 to form stretched thermoplastic film having a substantially uniform gauge.