Process for making thin oriented plastic strips and tape

Claim 1

IN THE PROCESS OF PRODUCING A THIN, FLAT TAPE OF ORIENTED POLYMERIC MATERIAL BY APPLYING A STRETCHING FORCE TO AN EXTRUDED LENGTH OF ORIENTABLE POLYMERIC MATERIAL HAVING AN ELONGATED CROSS SECTION TO DRAW THE EXTRUDED LENGTH TO A PERMANENTLY ELONGATED LENGTH OF ORIENTED MATERIAL OF REDUCED CROSS SECTION, THE IMPROVEMENT OF HEATING THE EXTRUDED LENGTH TO AN ORIENTATION TEMPERATURE IMMEDIATELY BELOW THE CRYSTALLIZING TEMPERATURE OF SAID MATERIAL AND PULLING SAIDD REHEATED, EXTRUDED LENGTH THROUGH A CONFINED PASSAGE BY MEANS OF THE STRETCHING FORCE IN FORMING THE ELONGATED, ORIENTED LENGTH AND MAINTAINING THE WALLS OF SAID CONFINED PASSAGE AT APROXIMATELY THAT OF SAID ORIENTATION TEMPERATURE, SAID PASSAGE HAVING TWO PARALLEL WALLS SPACED APART LESS THAN THE THICKNESS ASSUMED BY THE EXTRUDED LENGTH WHEN FREELY DRAWN AT ITS NATURAL DRAW RATIO BY A STRETCHING FORCE.