Patent ID: 8309206
Filing Date: 2012-11-13
Classification: B29C,Y10T

Abstract:
1. A method of manufacturing an oriented film (A) comprising extruding a thermoplastic polymer material through an extrusion die to produce a tubular form, orienting the tubular form, while the material is in a molten or semi-molten state, in a main direction of orientation during the haul-off from the die, where the main direction of orientation is at an angle between 0° and 45° to an axis of the tubular form, cutting the tubular form at an angle to its main direction of orientation to form a web having a longitudinal direction having an orientation at the angle, where the angle is no less than 20° to the longitudinal direction, at any stage after the haul off from the die, but at the latest in direct succession to the cutting, segmentally stretching either the tubular form or the web to form linear bosses distributed over the tubular form or web surface with a division between adjacent bosses of no larger than 3 mm, integrally connected by thinner webs, where the bosses and the webs extending in a direction which is parallel with the orientation, which forms an acute angle v to the longitudinal direction of the resulting web, and after the segmentally stretching and the cutting, shearing the bosses along one another under reorientation in the connecting webs to increase the angle v.