Process for the production of a molding from a preform composed essentially of polymerized units of tetrafluoroethylene

摘要

A process for the production of a molding from at least one preform, in which process the preform, which has been heated to 330 DEG to 400 DEG C., is pressed by means of a pressure difference which increases slowly during the shaping into or onto a rigid mold heated to about the same temperature, and is then cooled while the pressure difference is maintained and is released from the mold. During the shaping and cooling, the edges of the preform are secured in their original position. The process makes it possible to produce moldings which have a thin wall thickness and a good surface and which exhibit a residual shrinkage which is sufficiently small for most applications.