Patent GB-1173154-A (GB)
Title: Manufacture of Pyrolyzed Structures
IPC: B32B3/12
Filed: 1966-09-02
Abstract: 1,173,154. Coated porous structures. SCOTT PAPER CO. 2 Sept., 1966 [8 Sept., 1965; 17 Sept., 1965], No. 39451/66. Heading B2E. A porous structure comprises a plurality of cells, all of which are open to the atmosphere, the elements forming the cells being composed of material having an exterior of a cured, infusible resin and an interior which is a pyrolyzed product of an at least partially organic material which has a three-dimensional cellular structure, and is self-supporting at a temperature above the fusion temperature of the uncured exterior resin. The structures are made by subjecting a cellular body, the elements forming the cells of the body being comprised of an at least partially organic material which has a three-dimensional cellular structure and which has a contiguous exterior coating of a resin curable to an infusible state, to a temperature sufficient to volatilize and pyrolize the organic material without destroying the exterior resin. Structures which may be coated are honeycomb structures, reticulated polyurethane foam. The coating material may be temporarily attached to the structure prior to fusion or melting of the coating material over the surface of the structure, e.g. by initially coating the structure with a binding liquid such as water. Adhesives and wetting agents may be incorporated in the binding liquid. Coating materials mentioned are thermosetting resins such as epoxy resins, polyimides, polypyrones; polyoxazoles, phenolaldehyde resins, copolymers of epoxy resins with phenolic resins, with the urea resins, the melamine resins, with polyamide and with butadiene-acrylonitrile rubbers, and furane resins, polybenzimidazoles, arylene polyimides, poly Schiff bases, polyazines. The infusible resin may be at least partially pyrolized. The coated structures may be further coated with high temperature -oxidation-resistant organic resins applied in the same manner as described for the non-fusible resins. Oxidation resistant organic resins mentioned are polytetrafluoroethylene, fluorinated ethylene-propylene copolymers, polyvinylidene fluoride, polyimides, polybenzimidazoles, polyphenyl ethers. The structures can be used as a structural member or filtering matrix at elevated temperatures. In the Examples reticulated polyurethane foam was coated with 1) epoxy resin, 2) epoxy resin containing glass fibres, 3) phenolic resin, 4) polyester resin, utilising a dry tack adhesive comprising an ethylene-vinyl acetate copolymer and the structure subsequently heat-treated to pyrolize the polyurethane from the structure and to at least partially pyrolize the coating; 5), 6) a reticulated polyurethane foam is coated with epoxy resin utilizing ethylene-vinylacetate copolymer adhesive, the structure heated to pyrolize it and subsequently coated with a protective coating of fluorinated ethylene-propylene copolymer, polybenzimidazole using ethylene-vinyl acetate emulsion as adhesive; 7), 8) honeycomb materials made by the pyrolysis of coated honeycomb materials made from glass fibre cloth impregnated with a phenolic resin and having hexagonal cells were further coated with polybenzimidazole, polyvinylidene fluoride using an ethylene-vinyl acetate emulsion as adhesive.