# US 11,028,245 B2 · Porous air permeable polytetrafluoroethylene composites with improved mechanical and thermal properties > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,245 B2 - Document ID: US11028245B2 - Status: Granted - Kind: B2 - Application number: 15/827,413 - Filed: 2017-11-30 - Published: 2018-03-22 - Granted: 2021-06-08 - Earliest claimed: 2014-09-12 - Assignees: W. L. Gore & Associates, Inc. - Applicants: W. L. Gore & Associates, Inc. - Inventors: Anit Dutta; Leslie N. Rikleen - Web page: https://patentgrep.com/patent/US11028245B2 ## CPC - C08J 7/046: Forming abrasion-resistant coatings; Forming surface-hardening coatings - B01D 67/0088: {Physical treatment with compounds, e.g. swelling, coating or impregnation} - B01D 69/02: characterised by their properties - B01D 71/36: Polytetrafluoroethylene - B01D 71/641: {Polyamide-imides} - B01D 71/643: {Polyether-imides} - B32B 5/20: foamed in situ - B32B 5/32: {at least two} layers being foamed {and next to each other} - B32B 27/322: {comprising halogenated polyolefins, e.g. PTFE} - C08J 5/2293: {After-treatment of fluorine-containing membranes} - C08J 7/0427: {with only one layer of a composition containing a polymer binder (with more layers C08J7/042)} - C08J 7/056: Forming hydrophilic coatings - C09D 127/16: Homopolymers or copolymers of vinylidene fluoride - C09D 127/18: Homopolymers or copolymers of tetrafluoroethene - C09D 127/20: Homopolymers or copolymers of hexafluoropropene - C09D 175/04: Polyurethanes - C09D 179/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors - B01D 71/54: Polyureas; Polyurethanes - B01D 2325/22: Thermal or heat-resistance properties - B01D 2325/24: Mechanical properties, e.g. strength - B29C 55/005: {characterised by the choice of materials} - B32B 2255/102: synthetic resin or rubber layer being a foamed layer - B32B 2255/26: Polymeric coating - B32B 2266/025: Polyolefin - B32B 2266/06: Open cell foam - B32B 2307/724: Permeability to gases, adsorption - C08J 2475/04: Polyurethanes - C08J 2479/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) ## Abstract Porous air permeable expanded PTFE composite with enhanced mechanical and thermal properties are described. The node and fibril microstructure of expanded PTFE is coated on and within the node and fibril microstructure with a suitably chosen polymer to impart property enhancement while maintaining porosity. The coating polymer content of the composite is maintained between 3 and 25 weight percent of the composite and the areal mass of the composite is less than 75 gm/m2. Exemplary enhancement to properties may include, among others, Average Tensile Strength (ATS) (in MPa)×Z strength (in MPa) of 50 MPa2 or greater, preferably 100 MPa2 or greater, with air flow less than 500 Gurley seconds. Coating polymers with appropriate temperature resistance provides composites which further exhibit shrinkage of less than 10% at temperatures up to 300° C. with air flow of less than 500 Gurley seconds. ## Claims ### Claim 1 An article comprising: a porous, air-permeable composite comprising an expanded polytetrafluorocthylene (ePTFE) substrate having a microstructure comprising nodes, fibrils, and pores, said nodes being interconnected by said fibrils and said pores being a void space between said nodes and fibrils; and at least one continuous polymer coating, said polymer being a terpolymer of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP), wherein said at least one polymer coating coats only said nodes and fibrils throughout a thickness of said ePTFE substrate without occluding said pores of said ePTFE substrate, wherein said composite exhibits a mass per area of 75 gm/m2 or less, and a product of average tensile strength (ATS)×Z Strength of at least 50 MPa2 while maintaining an airflow of less than 500 Gurley seconds, and wherein the polymer content is between 3 and 25 weight percent of the ePTFE composite. ### Claim 2 (depends on 1) The article of claim 1, wherein said article has a strength in the L-direction of at least 0.4 MPa. ### Claim 3 (depends on 1) The article of claim 1, wherein said article maintains a Gurley airflow of 100 seconds or less. ### Claim 4 (depends on 1) The article of claim 1, wherein the ePTFE microstructure consisting substantially of fibrils. ### Claim 5 (depends on 1) The article of claim 1, wherein said article further comprises at least one filler. ### Claim 6 (depends on 1) The article of claim 1, wherein said composite comprises at least two ePTFE layers. ### Claim 7 An article comprising: a porous, air-permeable composite comprising an expanded polytetrafluoroethylene (ePTFE) substrate having a microstructure comprising nodes, fibrils, and pores, said nodes being interconnected by said fibrils and said pores being a void space between said nodes and fibrils; and at least one continuous polymer coating, said polymer being a terpolymer of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluompropylene (HFP), wherein said polymer coating coats only said nodes and fibrils throughout a thickness of said ePTFE substrate without occluding said pores of said ePTFE substrate, wherein said composite exhibits a product of average tensile strength (ATS)×Z Strength of 50 MPa2 or greater while maintaining an airflow of less than 500 Gurley seconds, and wherein the polymer content is between 3 and 25 weight percent of the ePTFE composite. ### Claim 8 An article comprising: a porous, air-permeable composite comprising an expanded polytetrafluoroethylene (ePTFE) substrate having a microstructure comprising nodes, fibrils, and pores, said nodes being interconnected by said fibrils and said pores being a void space between said nodes and fibrils; and at least one continuous polymer coating, said polymer being a terpolymer of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP), wherein said polymer coating coats only said nodes and fibrils throughout a thickness of said ePTFE substrate without occluding said pores of said ePTFE substrate, wherein said composite exhibits a mass per area of 75 gm/m2 or less, and a shrinkage of less than 10% in at least one direction when measured at a temperature of 200° C. while maintaining an airflow of less than 500 Gurley seconds, and wherein the polymer content is between 3 and 25 weight percent of the ePTFE composite. ### Claim 9 (depends on 8) The article of claim 8, wherein the ePTFE microstructure consists substantially of fibrils.