Dynamic vulcanization of fluorocarbon elastomers

Abstract

Processable rubber compositions contain a vulcanized fluorocarbon elastomer dispersed in a matrix of a non-fluorine containing thermoplastic polymeric material. In one embodiment the matrix forms a continuous phase and the vulcanized elastomeric material is in the form of particles forming a non-continuous phase. The compositions are made by combining a curative, an uncured fluorocarbon elastomer, and a thermoplastic material, and heating the mixture at a temperature and for a time sufficient to effect vulcanization of the elastomeric material, while mechanical energy is applied to mix the mixture during the heating step. Shaped articles such as seals, gaskets, O-rings, and hoses may be readily formed from the rubber compositions according to conventional thermoplastic processes such as blow molding, injection molding, and extrusion.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. patent application Ser. No. 10 / 620,213 filed on Jul. 15, 2003, the disclosure of which is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to thermoprocessable compositions containing cured fluorocarbon elastomers. It also relates to seal and gasket type material made from the compositions and methods for their production by dynamic vulcanization techniques. BACKGROUND OF THE INVENTION [0003] Cured elastomeric materials have a desirable set of physical properties typical of the elastomeric state. They show a high tendency to return to their original sized and shape following removal of a deforming force, and they retain physical properties after repeated cycles of stretching, including strain levels up to 1000%. Based on these properties, the materials are generally useful for making shaped articles such as seals and gaskets. [0004] Because they are ther...

AI Technical Summary

Problems solved by technology

Because they are thermoset materials, cured elastomeric materials can not generally be processed by conventional thermoplastic techniques such as injection molding, extrusion, or blow molding.

Although these and other rubber compounding operations are conventional and known, they nevertheless tend to be more expensive and require higher capital investment than the relatively simpler thermoplastic processing techniques.

Another drawback is that scrap generated in the manufacturing process is difficult to recycle and reuse, which further adds to the cost of manufacturing such articles.

Articles made from elastomeric materials, such as seals and gaskets, are in contact with such fluids during use, and are subject to a wide variety of challenging environmental conditions, including exposure to high temperature, contact with corrosive chemicals, and high wear conditions during normal use.

As a thermoset material, the cured fluorocarbon rubber is subject to the processing disadvantages noted above.

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