Patent ID: 7854870

Claim:
A process for the production of high tenacity, highly oriented polyolefin sheet having a high heat of fusion comprising: a) feeding a metered amount of polyolefin powder into the nip between two counter rotating heated calender rolls set at an initial gap smaller than the size of the smallest polyolefin powder particle and at an initial temperature above the melting point of the polyolefin powder; b) rolling the powder through the gap under these conditions until a coherent sheet of polyolefin is produced: c) once a coherent sheet of polyolefin exits the gap lowering the temperature in the gap to an operating temperature below the melting point of the polyolefin powder and increasing the gap to a desired operating level above the thickness of the largest powder particle; and d) drawing the coherent sheet under controlled tension at a temperature of between about 140 and 158° C. to produce a high tenacity, highly oriented polyolefin sheet having a high heat of fusion.