Patent ID: 11958214

Abstract:
An injection molded thermoplastic preform for blow moulding to form a container, the preform base of a central part having a first, downwardly and radially inwardly tapering portion therebetween which increases in thickness from a radially outer end of the first tapering portion adjacent to the hollow transition portion to a radially inner end of the first tapering portion adjacent to the gate part and the middle part opposite the gate part can allow the injected resin to be urged back through the gate at the end of the injection moulding cycle at a lower fluid pressure in the vicinity of the gate which is associated with high resin temperatures. The technical effect achieved by the first tapering portion is that crystallinity in the gate area is minimized or eliminated, which avoids or minimizes partial blocking of the gate which would otherwise restrict the injected resin from being urged back through the gate at the end of the injection moulding cycle.