Method of forming foamed fluoropolymer composites
First Claim
1. Process for foaming a composite structure comprising a layer of first fluoropolymer and a substrate in contact with said layer, said layer of first fluoropolymer being solid, said first fluoropolymer being foamable at a temperature at which said substrate is either less foamable or is non-foamable, said process comprising(a) heating said composite structure in which said layer of first fluoropolymer is solid to a foamable state for said first fluoropolymer,(b) pressurizing the heated composite structure with supercritical CO2,(c) depressurizing the pressurized heated composite structure while said first fluoropolymer is still in the foamable state, whereby said CO2 foams said layer of said first fluoropolymer, and(d) cooling said foamed composite structure.
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Accused Products
Abstract
Fluoropolymer is advantageously foamed by first forming a composite structure of a layer of the fluoropolymer to be foamed and a layer of different material such as a different fluoropolymer not to be foamed, followed by heating the composite structure to the foamable state for the layer of fluoropolymer to be foamed, pressurizing the heated composite structure with supercritical carbon dioxide, rapidly depressurizing the heated composite structure, whereby the foamable layer foams and the other layer foams less or not at all, and cooling the foamed composite structure.
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Citations
10 Claims
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1. Process for foaming a composite structure comprising a layer of first fluoropolymer and a substrate in contact with said layer, said layer of first fluoropolymer being solid, said first fluoropolymer being foamable at a temperature at which said substrate is either less foamable or is non-foamable, said process comprising
(a) heating said composite structure in which said layer of first fluoropolymer is solid to a foamable state for said first fluoropolymer, (b) pressurizing the heated composite structure with supercritical CO2, (c) depressurizing the pressurized heated composite structure while said first fluoropolymer is still in the foamable state, whereby said CO2 foams said layer of said first fluoropolymer, and (d) cooling said foamed composite structure.
Specification