Fluoropolymer compositions
AssigneeRaychem Corporation
InventorsEdward F. Chu, Vijay Reddy, Robert P. Saltman
Life of this patent
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Abstract
A composition which contains 35 to 85% by weight of a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP), 10 to 60% by weight of a copolymer of tetrafluoroethylene and perfluoropropylvinyl ether (PFA), and 5 to 60% by weight of melt-processable polytetrafluoroethylene (PTFE). The composition is particularly suitable for use as an insulating material on a substrate such as a resistive element in a conductive polymer heating cable. The composition has good physical properties, low creep, and low secondary crystallization, and exhibits little stress-cracking when exposed to elevated temperatures.
Claims13
A polymer composition comprising a polymer component which contains three different polymers which comprises
- (A) an amount x which is 35 to 85% by weight of the total polymer component of a first polymer which is a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP) as primary monomers optionally with one or more other monomers,
- (B) an amount y which is 10 to 60% by weight of the total polymer component of a second polymer which is a copolymer of tetrafluoroethylene and perfluoropropylvinyl ether (PFA) as primary monomers optionally with one or more other monomers, and
- (C) an amount z which is 5 to 60% by weight of the total polymer component of a third polymer which is (i) a fluoropolymer which is polytetrafluoroethylene (PTFE) and (ii) melt-processable,
- wherein the quantity (y+z)/x is 0.3 to 2 and the composition
- (1) has creep at 150.degree. C. and 300 psi for 10 hours of less than 15%,
- (2) has a modulus at 275.degree. C. of at least 5.times.10.sup.7 dynes/cm.sup.2,
- (3) has secondary crystallization of less than 20%, and
- (4) has a tensile strength at ambient temperature of at least 3000 psi.
Dependencies are inferred from the claim text.