Patent ID: 8815134
Filing Date: 2014-08-26
Classification: B29C,B29K,B29L,B30B

Abstract:
1. A process for manufacturing a homogeneous film of ultra-high molecular weight polyolefin comprising: applying a starting ultra-high molecular weight polyolefin with a weight average molecular weight of at least 500,000 gram/mole in powder form on a releasable support belt at a distance upstream from an isobaric double belt press comprising a lower belt, an upper belt on top of the lower belt, and pressure cushions to apply pressure to the polyolefin at a compaction zone between the lower and upper belts; preheating the support belt to increase a temperature of the ultra-high molecular weight polyolefin above a softening point of the ultra-high molecular weight polyolefin before entering the compaction zone; subsequently feeding the support belt with the ultra-high molecular weight polyolefin into the compaction zone between the upper and lower belts of the isobaric press; subjecting the support belt with the ultra-high molecular weight polyolefin to a compacting step using the isobaric press, wherein the compacting step is carried out at a temperature of at least 1° C. below an unconstrained melting point of the polyolefin and wherein the temperature is maintained within a temperature window of 2° C. to form a single layer film of compacted polyolefin; discharging the support belt and the single layer film of compacted polyolefin from the upper and lower belts of the isobaric press; separating the film of compacted polyolefin from the support belt; and subjecting the single layer film of compacted polyolefin to a rolling step and at least one stretching step at a temperature of at least 1° C. below the melting point of the polyolefin under process conditions.