Method of making erosion resistant coatings

Abstract

A method of applying multilayer polyurethane or polyurea coating compositions over a primer layer for protecting a leading edge substrate on an airfoil against liquid or solid particle erosion, the composition preferably made from an isocyanate-terminated prepolymer and curing agents, such as polyaspartic esters, aldimines and ketimines with a topcoat having flatting agent for matte coatings.

1 . A method of protecting an airfoil shaped substrate having a leading edge surface exposed in use to high speed impingement of liquid or solid particles comprising:
 depositing a layer of primer disposed on the leading edge surface;   forming a protective coating comprising a plurality of polyurethane or polyurea coating layers onto a leading edge of the airfoil shaped substrate overlying said layer of primer, at least one of said plurality of layers of polyurethane or polyurea coatings comprising a filler containing basecoat layer of a polyurethane or polyurea coating composition having incorporated therein at least one filler added at a concentration greater than the minimum amount useful as a flatting agent or colorant, said basecoat layer of a polyurethane or polyurea coating selected from the group consisting of an isocyanate-terminated prepolymer cured with a curing agent selected from a group consisting of an aldimine, a ketimine, a polyaspartic ester, a polyamine, a polyol and mixtures thereof, wherein the filler is selected from the group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof, wherein the basecoat layer has a tensile strength greater than 1000 psi (70 kg/cm 2 ), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F. when tested without said filler.   
     
     
         2 . The method of  claim 1  further comprising applying a polyurethane or polyurea matte topcoat layer over the filler containing basecoat layer. 
     
     
         3 . The method of  claim 2  wherein said matte topcoat layer has a minimum tensile strength of 1000 psi, an elongation at break higher than 350%, a tensile set less than 150%, a Shore A hardness of 44 A to 95 A and an 85 degree gloss less than 15. 
     
     
         4 . The method of  claim 1  wherein the filler is selected from a group consisting of electrically conductive fillers, heat conductive fillers, electromagnetic metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof. 
     
     
         5 . The method of  claim 1  wherein the airfoil shaped substrate with a leading edge is selected from the group consisting of an aircraft wing, a rotor blade, a turbine blade, a propeller, a radome, an antenna, a fan blade and a nose cone. 
     
     
         6 . The method of  claim 1  wherein at least one of said polyurethane or polyurea coatings comprises a water based polyurethane dispersion composition containing a filler, wherein the composition without the filler is configured to have a tensile strength greater than 1000 psi (70 kg/cm2), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F. 
     
     
         7 . The method of  claim 1  wherein at least one of said polyurethane or polyurea coatings comprises a water based dispersion selected from the group consisting of a water dispersion of a prereacted polyurethane having incorporated therein said at least one filler. 
     
     
         8 . The method of  claim 2  wherein said topcoat layer covering the filled basecoat layer has a minimum tensile strength of 1000 psi, an elongation at break higher than 350%, a tensile set less than 150% and a Shore A hardness of 44 to 95 A, and a 85 degree gloss less of 15. 
     
     
         9 . The method of  claim 2 , wherein the topcoat layer is a polyurethane or polyurea coating and the basecoat layer is formed from a polyisocyanate or an isocyanate-terminated prepolymer cured with a curing agent selected from a group consisting of an aldimine, a ketimine, a polyaspartic ester, a polyamine, a polyol and mixtures thereof having incorporated therein at least one filler added at a concentration greater than the minimum amount useful as a flatting agent or colorant. 
     
     
         10 . The method of  claim 9  wherein the filler is selected from a group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, graphite, boron nitride, aluminum nitride, silica coated aluminum nitride, carbon nanotubes, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and combinations thereof. 
     
     
         11 . The method of  claim 9  wherein the isocyanate-terminated prepolymer is derived from a diisocyanate selected from a group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4′-methylene dicyclohexyl diisocyanate, 4,4′-diisocyanatodiphenylmethane, p-phenylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 1,3-cyclohexyl diisocyanate; 1,4-cyclohexyl diisocyanate, 1,6-hexamethylene diisocyanate, diphenyl-4,4′-diisocyanate, dibenzyl-4,4′-diisocyanate, stilbene-4,4′-diisocyanate, benzophenone-4,4′-diisocyanate, 1,3- and 1,4-xylene diisocyanates, isophorone diisocyanate, 2,2,4- and/or 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,4′- and/or 4,4′-diisocyanato-dicyclohexyl methane, 2,4- and/or 4,4′-diisocyanato-diphenyl methane 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, diphenylmethane diisocyanate, and mixtures thereof. 
     
     
         12 . The method of  claim 9  where said airfoil shaped substrate is selected from the group of structures consisting of a rotor blade, propeller blade, aircraft wing, radome, antenna, fan blade and nose cone. 
     
     
         13 . The method of  claim 1  wherein said step of forming one or more polyurethane or polyurea coatings onto the airfoil shaped substrate comprises:
 coating said airfoil shaped substrate with a coating composition comprising a water based polyurethane dispersion containing a filler, wherein the composition without the filler is configured to have a tensile strength greater than 1000 psi (70 kg/cm2), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F. 
 
     
     
         14 . A method of protecting an airfoil shaped substrate against liquid and solid particle erosion comprising:
 applying a plurality of filler containing basecoat layers of a polyurethane or polyurea coating composition having incorporated therein at least one filler added at a concentration greater than the minimum amount useful as a flatting agent or colorant onto a releasable substrate, said filler containing basecoat layer selected from the group consisting of an isocyanate-terminated prepolymer cured with a curing agent selected from a group consisting of an aldimine, a ketimine, a polyaspartic ester, a polyamine, a polyol and mixtures thereof and the filler is selected from a group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof;   forming a predetermined shape;   removing said predetermined shape from the releasable substrate;   applying the predetermined shape to said airfoil shaped substrate; and   adhering said predetermined shape on the leading edge of said airfoil shaped substrate.   
     
     
         15 . The method of  claim 14  further comprising applying a plurality of topcoat layers of an polyurethane or polyurea coating composition over said plurality of filler containing basecoat layers. 
     
     
         16 . The method of  claim 14  further comprising applying a primer to the leading edge of said airfoil shaped substrate prior to applying the predetermined shape to said airfoil shaped substrate. 
     
     
         17 . The method of  claim 15  wherein said plurality of topcoat layers of an polyurethane or polyurea coating composition has incorporated therein filler selected from a group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof and said topcoat layer when measured prior to the addition of the filler has a tensile strength greater than 1000 psi (70 kg/cm2), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F. 
     
     
         18 . A method of protecting an airfoil shaped substrate against liquid and solid particle erosion comprising:
 forming a protective coating of a plurality of layers onto a leading edge of the airfoil shaped substrate comprising:   depositing a layer of primer on said airfoil shaped substrate;   applying an overlying plurality of layers of a polyurethane or polyurea coating selected from the group consisting of a water dispersion of a prereacted polyurethane, a polyisocyanate curable with a curing agent, and an isocyanate-terminated prepolymer, said polyurethane or polyurea coating having incorporated therein at least one filler added at a concentration greater than the minimum amount useful as a flatting agent or colorant wherein the filler is selected from a group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof, wherein the polyurethane or polyurea coating when tested without the filler has a tensile strength greater than 1000 psi (70 kg/cm 2 ), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F.   
     
     
         19 . The method according to  claim 18  further comprising a polyurethane or polyurea matte topcoat layer overlying said polyurethane or polyurea coating having a matte finish as measured according to ASTM D 523-89 (1999) with an 85 degree surface gloss less than 15. 
     
     
         20 . The method according to  claim 19  wherein said polyurethane or polyurea matte topcoat layer contains at least one filler selected from the group consisting of metal powders, metal flakes, metal fibers, milled metal fibers, metal-coated synthetic fibers, metal-coated glass spheres, metal-coated hollow spheres, graphite, carbon nanotubes, vapor grown carbon fibers, carbon fibers, milled carbon fibers, carbon coated synthetic fibers, buckyballs, electroactive polymers, conductive metal oxides, tertiary ammonium salt compounds, carbon blacks, coke, alumina, boron nitride, aluminum nitride, silica coated aluminum nitride, silicon carbide, silicas, fumed silicas, silicates, talc, calcium carbonate, polymer beads, urea formaldehyde, metal oxides, radar absorbing materials, microballoons, polytetrafluoroethylenes, polyolefins, polyamides, polyimides, polysilazanes, polysiloxanes, fluoropolymers, and mixtures thereof. 
     
     
         21 . The method according to  claim 19  wherein said polyurethane or polyurea matte topcoat layer has tensile strength greater than 1000 psi (70 kg/cm 2 ), an elongation at break greater than 350%, a tensile set of less than 150%, and a Shore A hardness of 44 A to 95 A as measured at 68° F. when tested without said filler.