GB1514277A - Oriented containers - Google Patents

Abstract

1514277 Injection blow moulding STANDARD OIL CO 29 Oct 1975 [31 Oct 1974] 44734/75 Heading B5A An oriented polyethylene terephthalate container is made by injecting a parison on a core in a first mould chamber, cooling the parison to form a dimensionally stable skin on it, transferring the parison on the core to a second mould chamber slightly bigger than the parison, blowing the parison into conformity with the second mould chamber at pressures above 10 psig and at a core temperature of no more than 265‹ F. (preferably 100-200‹ F.), transferring the partially blown parison still on the core to a third mould chamber and blowing it to its final shape at molecular orientation temperatures. It is preferred for the gap between the parison and the chamber wall of the second mould chamber to be 2À5% to 150% of the distance across the parison from outer surface to outer surface and it is preferred for the gap between the partially blown parison and the wall of the third mould chamber to be at least 50% of the distance across the partially blown parison from outer surface to outer surface. The temperature of the first mould adjacent the closed tip of the parison is advantageously lower than that of the rest of the mould, and the temperature of the second mould is higher than the tip defining portion of the first mould. During blowing in the third mould chamber the core may be extended axially to produce longitudinal orientation.