# US 2014/0154496 A1 · Conductive surfacing material for composite structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154496 A1 - Document ID: US20140154496A1 - Status: Published application - Kind: A1 - Application number: 14/089,962 - Filed: 2013-11-26 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: Cytec Industries Inc. - Applicants: Cytec Industries Inc. - Inventors: Junjie Jeffrey SANG; Dalip Kumar KOHLI - Web page: https://patentgrep.com/patent/US20140154496A1 ## CPC - H02G 13/80: {Discharge by conduction or dissipation, e.g. rods, arresters, spark gaps} - B32B 5/022: {Non-woven fabric} - B32B 5/12: characterised by the relative arrangement of fibres or filaments of {different layers, e.g. the fibres or filaments being parallel or perpendicular to each other} - B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)} - B32B 15/14: next to a fibrous or filamentary layer - B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)} - B32B 37/14: characterised by the properties of the layers - C08G 59/38: together with di-epoxy compounds - C08J 5/243: {using carbon fibres} - C08J 5/249: {characterised by the additives used in the prepolymer mixture} - C08K 7/18: inorganic - C08L 63/00: Compositions of epoxy resins; Compositions of derivatives of epoxy resins - H05K 9/0084: {comprising a single continuous metallic layer on an electrically insulating supporting structure, e.g. metal foil, film, plating coating, electro-deposition, vapour-deposition} - B32B 2260/021: Fibrous or filamentary layer - B32B 2260/023: Two or more layers - B32B 2260/046: Synthetic resin - B32B 2264/105: Metal - B32B 2264/107: Ceramic - B32B 2264/108: Carbon, e.g. graphite particles - B32B 2305/076: Prepregs - B32B 2307/202: Conductive - B32B 2307/536: Hardness - B32B 2605/08: Cars - B32B 2605/12: Ships - B32B 2605/18: Aircraft - C08L 2205/02: containing two or more polymers of the same C08L -group - C09D 163/00: Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins - Y02T 50/40: Weight reduction - Y10T 156/1002: with permanent bending or reshaping or surface deformation of self sustaining lamina - Y10T 428/249974: Metal- or silicon-containing element - Y10T 428/252: Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.] - H02G: INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - 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) - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An electrically conductive surfacing material capable of providing sufficient conductivity for lightning strike protection (LSP) and/or electromagnetic interference (EMI) shielding is disclosed. The conductive surfacing material is a multi-layered structure having a very thin conductive layer (e.g. solid metal foil) and a resin film formed on at least one surface of the conductive layer. The resin film is formed from a curable resin composition containing an epoxy novolac resin, a tri-functional or tetra-functional epoxy resin, ceramic microspheres, a latent amine-based curing agent, particulate inorganic fillers; and a toughening component. Optionally, the resin film further includes conductive additives to increase electrical conductivity of the surfacing material. The resin film exhibits high Tg as well as high resistance to paint stripper solutions. Furthermore, the conductive surfacing material is suitable for co-curing with fiber-reinforced resin composite substrates. ## Claims ### Claim 1 An electrically conductive surfacing material capable of providing lightning strike protection or electromagnetic interference shielding, the surfacing material being a multilayered structure comprising: (a) an electrically conductive layer having two opposite surfaces and a thickness of less than 3 mils and resistivity less than 10 mΩ; (b) a resin film formed on at least one surface of the conductive layer, wherein the resin film is formed from a curable composition comprising: an epoxy novolac resin having epoxy functionality of more than one; a tri-functional or tetra-functional epoxy resin; ceramic microspheres; a latent amine-based curing agent; particulate inorganic fillers; and at least one toughening agent selected from a group consisting of: (i) a pre-react adduct formed by the reaction of an epoxy resin, a bisphenol, and an elastomer; (ii) a copolymer of polyether sulfone (PES) and polyetherether sulfone (PEES); (iii) core-shell rubber (CSR) particles; and combinations thereof, and upon curing, the resin film has a glass transition temperature (Tg) of ≧180° C., and a surface pencil hardness of greater than 7H as measured in accordance with ASTM D-3363. ### Claim 2 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the resin film has a film weight in the range of 0.01-0.03 psf. ### Claim 3 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the conductive layer has a thickness within the range of 3 μm-38 μm. ### Claim 4 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the conductive layer is a metal foil having a thickness within the range of 3 μm-5 μm. ### Claim 5 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the metal foil comprises metal selected from copper, aluminum, bronze, or alloys thereof. ### Claim 6 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the resin film exhibits less than 0.5% fluid absorption and a reduction in hardness of not more than 2H pencil grades, after being in contact with a benzyl alcohol-based paint stripping solution for 7 days at ambient temperature within the range of 20° C.-25° C. ### Claim 7 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the resin film further comprises conductive particles or flakes distributed throughout the resin film. ### Claim 8 (depends on 7) The electrically conductive surfacing material of claim 7, wherein the conductive particles or flakes are formed of conductive materials selected from: silver, gold, aluminum, copper, bronze, carbon, and combinations thereof. ### Claim 9 (depends on 7) The electrically conductive surfacing material according to claim 7, wherein the surface resistivity of the multilayered structure is less than 5 mΩ. ### Claim 10 (depends on 1) The electrically conductive surfacing material of claim 1, wherein two resin films are formed on opposite surfaces of the metal layer such that the metal layer is sandwiched between the two resin films. ### Claim 11 (depends on 10) The electrically conductive surfacing material of claim 10, wherein the two resin films are different in composition. ### Claim 12 (depends on 10) The electrically conductive surfacing material of claim 10, wherein the two resin films are the same in composition. ### Claim 13 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the first resin layer exhibits a micro-crack density of less than 0.3 cracks/in2 after being subjected to a 2000× thermal cycling testing between −55° C. and 71° C. ### Claim 14 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the epoxy novolac resin in the curable composition has the following structure: where R═H and n=0-5, the tetra-functional epoxy resin is tetraglycidyl 4,4″-diaminodiphenylmethane, and the tri-functional epoxy is triglycidyl ether of aminophenol. ### Claim 15 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the at least one toughening agent in the thermosetting composition includes a pre-react adduct formed by the reaction of diglycidylether of tetrabromo Bisphenol A, bisphenol A, and amine terminated butadiene acrylonitrile (ATBN) or carboxyl terminated butadiene acrylonitrile (CTBN) elastomer. ### Claim 16 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the curable composition comprises the pre-react adduct and PES-PEES copolymer as toughening agents. ### Claim 17 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the ceramic microspheres are hollow microspheres made of silica-alumina ceramic material and having particle size within the range of 1-50 microns. ### Claim 18 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the epoxy resins and the ceramic microspheres make up more than 35% by weight of the total weight of the thermosetting composition. ### Claim 19 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the curable composition further comprises a bisurea as a curing accelerator. ### Claim 20 (depends on 1) A conductive prepreg tape suitable for Automated Tape Laying (ATL) or Automated Fiber Placement (AFP) which is derived from the electrically conductive surfacing material of claim 1. ### Claim 21 (depends on 20) The conductive prepreg tape of claim 20 having a width within the range of 0.125 in-1.5 in. ### Claim 22 (depends on 20) The conductive prepreg tape of claim 20 having a width within the range of 6-12 in. ### Claim 23 (depends on 20) A method of fabricating a composite structure comprising: laying up prepreg tapes in an Automated Tape Laying (ATL) or Automated Fiber Placement (AFP) process, using an automated system equipped with means for dispensing and compacting prepreg tapes directly on a molding surface for forming a composite structure; incorporating the conductive prepreg tape of claim 20 into the ATL or AFP process so that the conductive prepreg tape is positioned as an outermost layer in the final composite structure. ### Claim 24 (depends on 1) A composite structure comprising: a composite substrate comprising reinforcement fibers impregnated with a matrix resin; and the electrically conductive surfacing material of claim 1 formed on a surface of the composite substrate such that the metal layer is positioned between the resin film and the composite substrate. ### Claim 25 (depends on 24) The composite structure of claim 24, wherein said composite substrate is a prepreg layup, which is comprised of a plurality of prepreg plies arranged in a stacking arrangement, each prepreg ply comprising reinforcing fibers impregnated with a matrix resin.