| 摘要 |
An injection moulded thermoplastic preform 2 for blow moulding to form a container, comprises a closed base portion 4 comprising a central portion 14 which extends over at least 50% of an internal radius of a lower end 16 of a hollow body portion and is either substantially flat or has a shallow concave or convex internal curvature. A transition portion 8 comprises an upwardly and radially outwardly tapering portion 24 extending away from the central portion to connect to the hollow body portion, the tapering portion being inclined at an angle of from 1-20degrees to a longitudinal axis L of the preform and the tapering portion increasing in thickness from the central portion to the hollow body portion. A method of injection moulding a thermoplastic preform is further provided characterised by moving of a core rearwardly during the injection and moving the core forwardly after at least a proportion of the thermoplastic material has been injected into the mould cavity. |
