# US 11,027,856 B2 · Surfacing materials 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 11,027,856 B2 - Document ID: US11027856B2 - Status: Granted - Kind: B2 - Application number: 15/778,035 - Filed: 2016-11-29 - Published: 2018-12-06 - Granted: 2021-06-08 - Earliest claimed: 2015-11-30 - Assignees: Cytec Industries Inc. - Applicants: Cytec Industries Inc. - Inventors: Junjie Jeffrey Sang; Dalip Kumar Kohli; Kevin R. Mullery - Web page: https://patentgrep.com/patent/US11027856B2 ## CPC - B64D 45/02: Lightning protectors; Static dischargers - B32B 3/12: characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure - B32B 3/266: {characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12} - B32B 5/022: {Non-woven fabric} - B32B 5/024: {Woven fabric} - B32B 5/18: characterised by features of a layer {of} foamed material - B32B 5/245: {another layer next to it being a foam layer} - 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 7/12: using interposed adhesives or interposed materials with bonding properties - B32B 9/007: {comprising carbon, e.g. graphite, composite carbon} - B32B 9/045: {of synthetic resin} - B32B 9/047: {made of fibres or filaments} - B32B 15/08: of synthetic resin - B32B 15/088: comprising polyamides - B32B 15/09: comprising polyesters - 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 21/08: of synthetic resin - B32B 21/10: Next to a fibrous or filamentary layer - B32B 27/065: {of foam} - B32B 27/10: of paper or cardboard - B32B 27/12: next to a fibrous or filamentary layer - B32B 27/18: characterised by the use of special additives - B32B 27/20: using fillers, pigments, thixotroping agents - B32B 27/26: using curing agents - B32B 27/281: {comprising polyimides} - B32B 27/285: {comprising polyethers} - B32B 27/286: {comprising polysulphones; polysulfides} - B32B 27/288: {comprising polyketones} - B32B 27/34: comprising polyamides - B32B 27/36: comprising polyesters - B32B 29/02: next to a fibrous or filamentary layer - B64C 1/12: Construction or attachment of skin panels - B64C 3/20: Integral or sandwich constructions - B32B 2250/04: 4 layers - B32B 2255/02: on fibrous or filamentary layer - B32B 2255/205: Metallic coating - B32B 2255/26: Polymeric coating - B32B 2260/021: Fibrous or filamentary layer - B32B 2260/046: Synthetic resin - B32B 2262/0261: Polyamide fibres - B32B 2262/0276: Polyester fibres - B32B 2262/101: Glass fibres - B32B 2262/106: Carbon fibres, e.g. graphite fibres - B32B 2264/10: Inorganic particles - B32B 2264/102: Oxide or hydroxide - B32B 2264/107: Ceramic - B32B 2264/108: Carbon, e.g. graphite particles - B32B 2307/202: Conductive - B32B 2307/4026: within the layer by addition of a colorant, e.g. pigments, dyes - B32B 2307/54: Yield strength; Tensile strength - B32B 2307/718: Weight, e.g. weight per square meter - B32B 2307/7265: Non-permeable - B32B 2307/732: Dimensional properties - B32B 2571/00: Protective equipment - B32B 2605/18: Aircraft - Y02T 50/40: Weight reduction - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - B64C: AEROPLANES; HELICOPTERS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Multifunctional surfacing materials for use in composite structures are disclosed. According to one embodiment, the surfacing material includes (a) a stiffening layer, (b) a curable resin layer, (c) a conductive layer, and (d) a nonwoven layer, wherein the stiffening layer (a) and the nonwoven layer (d) are outermost layers, and the exposed surfaces of the outermost layers are substantially tack-free at room temperature (20° C. to 25° C.). The conductive layer may be interposed between the curable resin layer and the stiffening layer or embedded in the curable resin layer. According to another embodiment, the surfacing material includes a fluid barrier film between two curable resin layers. The surfacing materials may be in the form of a continuous or elongated tape that is suitable for automated placement. ## Claims ### Claim 1 An integrated electrically conductive surfacing material comprising: (a) a stiffening layer; (b) a curable resin layer comprising one or more multifunctional epoxy resins and a curing agent; (c) a conductive layer between the stiffening layer and the curable resin layer; and (d) a nonwoven layer laminated to the curable resin layer, wherein the stiffening layer (a) and the nonwoven layer (d) are outermost layers and the exposed surfaces of the outermost layers are substantially tack-free at room temperature (20° C. to 25° C.), and wherein the stiffening layer is a nonporous thermoplastic layer comprising one or more polyaryletherketone (PAEK) polymers. ### Claim 2 (depends on 1) The electrically conductive surfacing material of claim 1, wherein the PAEK polymers are selected from the group consisting of: poly (ether ketone) (“PEK”), poly (ether ether ketone) (“PEEK”), poly (ether ketone ketone) (“PEKK”), poly (ether ketone ether ketone ketone) (“PEKEKK”), poly (ether ether ketone ether ether ketone) (“PEEKEEK”), poly (ether diphenyl ketone) (“PEDK”), poly (ether diphenyl ether ketone) (“PEDEK”), poly (ether diphenyl ether ketone ketone) (“PEDEKK”), and poly (ether ketone ether naphthalene) (“PEKEN”). ### Claim 3 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the conductive layer is a porous or nonporous metallic layer of copper, aluminum, bronze, titanium, or alloys thereof. ### Claim 4 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the conductive layer is a nonporous layer having a thickness of less than about 76 μm. ### Claim 5 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the conductive layer is a porous layer with an areal weight within the range of about 60 gsm to about 350 gsm. ### Claim 6 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the conductive layer is a metal screen or an expanded metal foil. ### Claim 7 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the conductive layer is a nonporous metal foil. ### Claim 8 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the nonwoven layer (d) comprises randomly oriented fibers selected from the group consisting of: polymeric fibers, inorganic fibers, metal-coated fibers, and combinations thereof. ### Claim 9 (depends on 8) The electrically conductive surfacing material of claim 8, wherein the fibers of the nonwoven layer (d) are selected from the group consisting of: carbon fibers, metal-coated carbon fibers, metal-coated glass fibers, metal-coated polyester fibers, metal-coated polyamide fibers, and combinations thereof. ### Claim 10 (depends on 9) The electrically conductive surfacing material of claim 9, wherein the fibers of the nonwoven layer (d) are selected from the group consisting of: polyamide fibers, polyester fibers, glass fibers, and combinations thereof. ### Claim 11 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the nonwoven layer (d) has an areal weight within the range of about 10 gsm to about 50 gsm. ### Claim 12 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the nonwoven layer (d) further comprises a metal coating, which is not in contact with the curable resin layer (b). ### Claim 13 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the surfacing material is in the form of a continuous or elongated tape having a width in the range of about 0.125 in to about 12 in and a length that is at least ten (10) times its width. ### Claim 14 (depends on 13) The electrically conductive surfacing material according to claim 13, wherein the total thickness of the tape is within the range of about 76 μm to about 229 μm. ### Claim 15 (depends on 13) A method for forming a composite structure comprising: forming a composite substrate, which comprises reinforcement fibers impregnated with a curable matrix resin; dispensing a plurality of the electrically conductive surfacing material of claim 13, side by side, directly onto a composite substrate by an automated placement process to form a protective surfacing layer on the composite substrate, wherein the stiffening layer in the surfacing material is facing the composite substrate during automated placement; and co-curing the protective surfacing layer and the composite substrate. ### Claim 16 (depends on 15) The method of claim 15, wherein the composite substrate is formed by laying up prepreg tapes in an automated placement process, which includes dispensing and compacting prepreg tapes directly on a molding surface. ### Claim 17 (depends on 1) The electrically conductive surfacing material according to claim 1, wherein the curable resin layer further comprises: a polymeric toughening agent selected from: thermoplastic polymers; elastomers; core-shell rubber particles; a pre-react adduct which is a reaction product of an epoxy resin, a bisphenol, and an elastomeric polymer; ceramic microspheres, and particulate inorganic fillers that are not ceramic microspheres. ### Claim 18 An integrated electrically conductive surfacing material comprising: (a) a stiffening layer; (b) a curable resin layer comprising one or more thermoset resins and a curing agent; (c) a conductive layer between the stiffening layer and the curable resin layer; and (d) a nonwoven layer laminated to the curable resin layer, wherein the stiffening layer (a) and the nonwoven layer (d) are outermost layers and the exposed surfaces of the outermost layers are substantially tack-free at room temperature of 20° C. to 25° C., and wherein the stiffening layer is a nonporous thermoplastic layer having the following properties: a tensile modulus of from about 640 MPa (or 93 ksi) to about 2.1 GPa (or 305 ksi), as measured by ASTM D-882; a tensile strength at yield of from about 27 MPa (or 4 ksi) to about 76 MPa (or 11 ksi), as measured by ASTM D-882, a tensile strength at break of from about 41 MPa (or 5.9 ksi) to about 110 MPa (or 16 ksi), as measured by ASTM D-882; and an elongation at yield or break of from about 4% to about 10%, as measured by ASTM D-882, all properties being determined at about 23° C. ### Claim 19 A composite structure comprising: a composite substrate comprising reinforcement fibers impregnated with a curable matrix resin; and an integrated electrically conductive surfacing material comprising: (a) a nonporous thermoplastic layer that functions as a stiffening layer; (b) a curable resin layer comprising one or more thermoset resins and a curing agent; (c) a conductive layer between the nonporous thermoplastic layer and the curable resin layer; and (d) a nonwoven layer laminated to the curable resin layer, wherein the nonporous thermoplastic layer (a) and the nonwoven layer (d) are outermost layers, and the exposed surfaces of the outermost layers are substantially tack-free at a temperature in the range of 20° C. to 25° C., and wherein the electrically conductive surfacing material is laminated to a surface of the composite substrate such that the nonporous thermoplastic layer (a) is in contact with the composite substrate. ### Claim 20 (depends on 19) The composite structure of claim 19, wherein said composite substrate is a prepreg layup, which comprises a plurality of prepreg plies arranged in a stacking arrangement, each prepreg ply comprising unidirectional reinforcing fibers impregnated with or embedded in a curable matrix resin.