Elastomeric compositions containing fluoropolymer blends

Abstract

Processable rubber compositions contain a vulcanized fluorocarbon elastomer dispersed in a thermoplastic matrix comprising a fully fluorinated polymer and a partially fluorinated polymer. The processing temperature is below the melting point of the fully fluorinated polymer. The compositions are made by combining a curative, uncured fluorocarbon elastomer, a fully fluorinated thermoplastic, and a partially fluorinated 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 / 813,527 filed on Mar. 30, 2004, the disclosure of which is incorporated herein by reference.INTRODUCTION [0002] The present invention relates to fluorine containing elastomer compositions. [0003] Cured elastomers or rubbers have a variety of physical properties useful for applications in molded articles. Among the properties are a high degree of flexibility, elasticity, and resistance to compression set. As such they find use in a variety of applications, such as seals and gaskets. Uncured elastomers or rubbers are in the form of a resin or gum. To obtain a molded article with suitable elastomeric properties, the uncured resins are crosslinked or cured with a variety of crosslinking agents. [0004] For conventional elastomers, cure is generally carried out in a mold under conditions of temperature and pressure suitable for forming a cured or partially cured article. B...

AI Technical Summary

Benefits of technology

[0010] Methods for making the processable rubber composition involve mixing an elastomeric component and a thermoplastic component in the presence of a curative agent and heating during mixing to effect cure of the elastomeric component. In preferred embodiments, the elastomeric component is a fluorocarbon elastomer and the thermoplastic component is a fluoroplastic blend as described above. Shaped articles may be made by melt processing the rubber compositions with conventional thermoplastic techniques. Such techniques involve melting and processing the rubber compositions at temperatures below the melting point of the fully fluorinated polymer, and preferably below 280° C.

Problems solved by technology

Because the curing reaction produces a thermoset material, conventional rubber compositions cannot be processed after the elastomer is cured.

A drawback of using fluorinated thermoplastics in such processable compositions is that their melting point is generally higher than the stability range of the cured elastomer.

Images