Patent ID: 7025917
Filing Date: 2006-04-11
Classification: B29C,B29K,C08J,Y10T

Abstract:
1. A method for production of an oriented polyolefin sheet comprising the steps of: (a) extruding polyolefin having a weight average molecular weight of 100,000–500,000 into a primary sheet; (b) roll-drawing said primary sheet having a thickness of t mm at a roll-drawing ratio of at least x (having a value of at least 5) to provide a roll-dawn sheet, with a proviso that the primary sheet prior to being roll-drawn is subjected to a pulling stress in a range of x/5t MPa to 20 MPa and the roll-drawn sheet is taken off while subjected to a pulling stress of at least xt/50 MPa; and (c) stretching said roll-drawn sheet using at least one roll such that a total drawing ratio, a product of said roll-drawing ratio and the stretch ratio, is at least 15.