Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1978-09-15
1980-07-01
Lawrence, Evan K.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
162152, 162156, 162164R, 162168R, 162183, 427244, 427387, 428273, 428290, B32B 2704
Patent
active
042106974
ABSTRACT:
A process is provided for preparing hydrophobic porous fibrous sheet material suitable for use as a filter due to its inertness, strength, resistance to deterioration at elevated temperatures, and porosity, comprising impregnating a porous fibrous substrate with an aqueous dispersion consisting essentially of polytetrafluoroethylene or polytrifluorochloroethylene in an amount within the range from about 2 to about 40% by weight of the emulsion, and a silicone resin prepolymer such as a reactive polydimethylsiloxane in an amount within the range from about 0.1 to about 8% by weight of the emulsion; and drying the substrate at a temperature above about 525.degree. F. to cure the silicone resin prepolymer, forming a hydrophobic polymer, and sinter-bond the polytetrafluoroethylene or polytrifluorochloroethylene thereto and to the substrate, thereby forming a hydrophobic porous fibrous sheet material that is inert, has a high strength, and a high resistance to deterioration at elevated temperature; each of the silcone polymer and polytetrafluoroethylene or polytrifluorochloroethylene unexpectedly synergizing the hydrophobicity and strength imparted to the substrate by the other. A hydrophobic porous fibrous sheet material also is provided, comprising a substrate of porous fibrous sheet material impregnated with a composition consisting essentially of polytetrafluoroethylene or polytrifluorochloroethylene and a silicone resin, said polytetrafluoroethylene or polytrifluorochloroethylene being sinter-bonded to the silicone resin and to the substrate, each of the silicone polymer and polytetrafluoroethylene or polytrifluorochloroethylene synergizing the hydrophobicity and strength imparted to the substrate by the other.
REFERENCES:
patent: 3053762 (1962-09-01), Adiletta
patent: 3385812 (1968-05-01), Brachman
patent: 3723264 (1973-03-01), Le Duc et al.
patent: 4125673 (1978-11-01), Roth et al.
Lawrence Evan K.
Pall Corporation
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