Foamable compositions for container closure gaskets.

摘要

This invention relates to a process for providing a foamed gasket in a container closure, especially for metal bottle caps, and to the compositions for use in the process. The composition is in the form of an extrudate and comprises a thermoplastic polymer matrix which is substantially free of chlorinated-olefin based polymer material, with a foaming agent. The gasket forming composition is introduced into the closure in the form of a molten or semi-molten extrudate. The composition is then moulded in the closure at a temperature below the decomposition temperature of the foaming agent and then the gasket is heated to a temperature at which the foaming agent decomposes to produce a foamed gasket. <IMAGE>