Plastic preform for production of non-round, particularly oval, containers has variable wall thickness around the circumference to compensate for different degrees of stretch

摘要

Wall thickness of the preform(11,12,15) around its circumference changes so that areas which are stretched further during inflation to form a container have a greater wall thickness than areas which undergo less stretching. The outer contor(9) and internal contor(10) of the preform(11) when viewed in cross-section may be non-circular. In different forms of the cross-section: a) both outer and inner contors may be oval; b) the outer contor(16) is circular and the inner contor(17) is oval; c) the inner contor(14) is circular and outer contor(13) oval. Wall thickness changes smoothly. Preforms are either injection molded or extrusion blow molded. An Independent claim is included for a process for manufacturing non-round, in particular oval-shaped, containers in a reheat process in which the claimed preforms taken from storage are rotated while passing through a heating zone and are heated uniformly around the circumference.