Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
  • B05D7/54—No clear coat specified
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • 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
  • C09D181/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur, with or without nitrogen, oxygen, or carbon only; Coating compositions based on polysulfones; Coating compositions based on derivatives of such polymers
  • C09D181/02—Polythioethers; Polythioether-ethers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/042—Coating with two or more layers, where at least one layer of a composition contains a polymer binder
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • 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
  • C09D181/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur, with or without nitrogen, oxygen, or carbon only; Coating compositions based on polysulfones; Coating compositions based on derivatives of such polymers
  • C09D181/04—Polysulfides
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • 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
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2400/00—Characterised by the use of unspecified polymers
  • C08J2400/26—Elastomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2481/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen, or carbon only; Polysulfones; Derivatives of such polymers
  • C08J2481/02—Polythioethers; Polythioether-ethers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2481/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen, or carbon only; Polysulfones; Derivatives of such polymers
  • C08J2481/04—Polysulfides

Definitions

• the present invention relates generally to elastomeric multilayer composite coatings in which the elastomeric basecoat can fracture before the topcoat when stress is applied to the composite coating, the composite coatings being useful for coating the interior of fuel storage containers to inhibit fuel leakage therefrom.
• sealing integral fuel tank systems involves faying, surface sealing, filleting and brush application of a sealant.
• sealant application Prior to sealant application, the substrate surface must be thoroughly cleaned and the sealant meticulously applied by well-trained personnel. In spite of controlled application procedures, the resulting coating is often found to leak upon inspection.
• Locating defects in the coating is a difficult and time-consuming procedure. Furthermore, repair and resealing is difficult, requiring old sealant material to be mechanically removed from the substrate.
• a coating and/or sealant suitable for easy application to a substrate by conventional techniques such as spraying, brushing, rollering, or fill and drain techniques.
• the novel coating or sealant should adhere to a variety of metallic, composite, silaceous and polymeric substrates, provide coverage of pinholes and imperfections in the substrate and maintain its integrity when subjected to impact and vibration.
• a composite coating which comprises (a) an elastomeric basecoat formed from a curable basecoat composition deposited upon a surface of a substrate; and (b) a topcoat applied over the basecoat, the topcoat being different from the basecoat and being formed from a curable topcoat composition comprising a polythioether material.
• Another aspect of the present invention is a composite coating comprising: (a) an elastomeric basecoat formed from a curable basecoat composition deposited upon a surface of a substrate, the curable basecoat composition comprising a polymeric material selected from the group consisting of polyurethanes, polysulfides, polythioethers, copolymers and mixtures thereof; and (b) a topcoat applied over the basecoat, the topcoat being different from the basecoat and having a higher tensile strength and percent elongation than the elastomeric basecoat.
• a substrate coated with the multi- component composite coating also is provided.
• Yet another aspect of the present invention is a process of inhibiting fuel leakage from an interior portion of a fuel storage container, comprising the step of: (a) coating an interior portion of a fuel storage tank with a composite coating comprising: (i) an elastomeric basecoat formed from a curable basecoat composition deposited upon the surface of the substrate; and (ii) a topcoat applied over the basecoat, the topcoat being different from the basecoat and being formed from a curable topcoat composition comprising a polythioether material.
• a composite (multilayer) coating of the present invention which comprises an elastomeric basecoat deposited upon a surface of a substrate and a topcoat applied over at least a portion of the basecoat.
• the elastomeric basecoat is formed from a curable basecoat composition which comprises one or more curable polymeric materials which are preferably elastomeric when cured.
• curable polymeric materials include crosslinkable or self-crosslinking polysulfides, polythioethers, polyurethanes, copolymers and mixtures thereof.
• the curable basecoat composition comprises a sulfur-containing material such as one or more polythioethers or polysulfides.
• Useful polysulfides comprise recurring polysulfide linkages between organic radicals, each organic radical having at least one primary carbon atom for the connection to the disulfide linkage.
• Useful polymers comprise one or more units having the structural formula:
• R is an divalent or polyvalent organic radical including but not limited to alkyl, alkylene, or oxyhydrocarbon such as diethylformal; m is a number of 2 or more, preferably 2 to 4 inclusive, and is known as the sulfur rank of the polymer; and n is an integer greater than 1, preferably 5 to 50. R optionally includes similar pendant groups.
• Useful solid polysulfides preferably have a number average molecular weight of greater than about 100,000, as determined by gel permeation chromatography using a polystyrene standard.
• Preferred polysulfides have a number average molecular weight ranging from about 300 to 15,000 and are generally liquids at ambient temperature (about 25°C) and atmospheric pressure (about 760 mm Hg). More preferably, the number average of the polysulfide polymer ranges from about 500 to about 10,000.
• the polysulfide optionally has one or more terminal or pendant hydroxy or mercaptan functional groups. Preferably, the polysulfide has mercaptan terminal functional groups.
• Preferred polysulfides include LP polysulfide polymers which are commercially available from Morton International, such as LP-2, LP-3 and LP- 32, and polysulfides such as are disclosed in U.S. Patent Nos. 1,962,460 and
• Useful polythioether materials include those having one or more units of the general structural formula:
• R 1 , R 2 , R 3 and R 4 are each independently selected from aliphatic groups having from one to six carbon atoms and x, y and n are each independently selected from integers equal to or greater than 1.
• At least one of the aliphatic groups can further comprise at least one pendent group selected from the group consisting of substituted or unsubstituted aliphatic groups having from 1 to 12 carbon atoms, cycloaliphatic groups and aryl groups.
• the substituted aliphatic group can comprise from 1 to 12 carbon atoms and one or more heteroatoms selected from the group consisting of oxygen, nitrogen and sulfur.
• the radicals R 1 , R 2 , R 3 and R 4 are each independently C,-C 3 aliphatic groups. More preferably, R 2 , R 3 and R 4 are ethyl and R 1 is isopropyl. Still more preferably, y is greater than x and n is such that the number average molecular weight of the polythioether is between about 300 and 15,000 such that the polythioether is a liquid at ambient temperature and atmospheric pressure.
• the polythioether material can include one or more pendant or terminal functional groups, such as hydroxyl, mercaptan, or alkyl.
• Useful polythioether materials include those disclosed in U.S. Patents Nos. 4,366,307; 5,912,319 and 5,959,071, each of which is incorporated by reference herein, and PERMAPOL P-3 and 855 polymers which are commercially available from PRC-DeSoto International.
• a preferred polythioether-containing composition is PR-2911, which is commercially available from PRC-DeSoto.
• Useful polyurethanes include those prepared by reacting one or more polyols with one or more polyisocyanates.
• Useful polyols include polyester polyols, polyether polyols, as well as diols or triols such as ethylene glycol, propylene glycol, butylene glycol, glycerol and trimethylolpropane.
• Useful polyisocyanates can include aliphatic polyisocyanates, cycloaliphatic polyisocyanates, or aromatic polyisocyanates.
• the polymeric material comprises about 30 to about 55 weight percent of the curable basecoat composition on a basis of total weight of the curable basecoat composition, and more preferably about 40 to about 50 weight percent.
• the curable basecoat composition further comprises one or more curing agents.
• suitable curing agents include polyamines, polyols, polyisocyanates, metal oxides, polyepoxides and mixtures thereof.
• Useful polyamines include primary or secondary diamines or polyamines in which the radicals attached to the nitrogen atoms can be saturated or unsaturated, aliphatic, alicyclic, aromatic, aromatic-substituted- aliphatic and aliphatic-substituted-aromatic.
• exemplary suitable aliphatic and alicyclic diamines include 1,2-ethylene diamine, isophorone diamine.
• Suitable aromatic diamines include diethyltoluene diamine and methylene diphenyl diamine (MDA).
• Useful triamines include diethylene triamine.
• Useful polyols include polyoxyalkylene polyols, polyester polyols, polyoxytetra methylene polyols, polyurethane polyols, and diols or triols such as ethylene glycol, propylene glycol, butylene glycol, glycerol and trimethylolpropane.
• Useful polyisocyanates include blocked or unblocked polyisocyanates including aromatic diisocyanates; aliphatic diisocyanates such as 1,6- hexamethylene diisocyanate; and cycloaliphatic diisocyanates such as isophorone diisocyanate and 4,4'-methylene-bis(cyclohexyl isocyanate).
• Suitable blocking agents for the polyisocyanates include lower aliphatic alcohols such as methanol, oximes such as methyl ethyl ketoxime and lactams such as caprolactam.
• Useful metal oxides include manganese dioxide (such as AT-407 which is commercially available from Eastman Chemical Co.), lead oxide, calcium peroxide, barium peroxide and zinc oxide.
• Useful polyepoxides include at least two epoxy groups per molecule.
• Useful polyglycidyl ethers of polyhydric alcohols can be formed by reacting epihalohydrins with polyhydric alcohols, such as dihydric alcohols, in the presence of an alkali condensation and dehydrohalogenation catalyst such as sodium hydroxide or potassium hydroxide.
• Suitable polyhydric alcohols can be aromatic, aliphatic or cycloaliphatic.
• suitable aromatic polyhydric alcohols include phenols which are preferably at least dihydric phenols.
• Non-limiting examples of aromatic polyhydric alcohols useful in the present invention include dihydroxybenzenes, for example resorcinol and hydroquinone; bis(4-hydroxyphenyl)-l,l-isobutane; 4,4- dihydroxybenzophenone; bis(4-hydroxyphenyl)- 1,1 -ethane; bis(2- hydroxyphenyl)methane; 1,5-hydroxynaphthalene; 4-isopropylidene bis(2,6- dibromophenol); l,l,2,2-tetra(p-hydroxy phenyl)-ethane; l,l,3-tris(p-hydroxy phenyl)-propane; novolac resins; bisphenol F; long-chain bisphenols; and 2,2- bis(4-hydroxyphenyl)propane, i.e., bisphenol A, which is preferred.
• dihydroxybenzenes for example resorcinol and hydroquinone
• Non-limiting examples of aliphatic polyhydric alcohols include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1 ,2-propylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, pentamethylene glycol, polyoxyalkylene glycol; polyols such as sorbitol, glycerol, 1,2,6-hexanetriol, erythritol and trimethylolpropane; and mixtures thereof.
• glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1 ,2-propylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, pentamethylene glycol, polyoxyalkylene glycol
• polyols such as sorbitol, glycerol, 1,2,6-hexanetriol, erythritol and trimethylolpropane; and mixtures thereof.
• Suitable epoxy-functional materials have an epoxy equivalent weight ranging from about 150 to about 200, as measured by titration with perchloric acid using methyl violet as an indicator.
• An example of a suitable commercially available epoxy-functional material is EPON® 828 epoxy resin, which is an epoxy functional diglycidyl ether of bisphenol A prepared from bisphenol-A and epichlorohydrin and is commercially available from Shell Chemical Company.
• the curing agent is added to the curable basecoat composition immediately prior to application.
• Selection of a curing agent is dependent upon the terminal functionalities of the polymeric material in the basecoating composition.
• isocyanates induce cure of polyamines or polyols; and epoxies, metal oxides and metal peroxides each induce cure of thiol groups.
• Cure of the basecoating composition is achieved by thoroughly mixing the polymeric material with the curing agent and subjecting the composition to atmospheric and temperature conditions conducive for cure.
• the polymeric material cures in the presence of the curing agent in ambient air.
• cure occurs at a temperature between about 10 and about 150°C.
• the concentration and identity of the curing agent are chosen to exact a cure within a few hours at ambient temperature and atmospheric pressure. The time required for cure depends in part upon the specific formulation and the nature and concentration of cure catalysts.
• the curing agent can comprise about 9 to about 100 weight percent of the curable basecoat composition on a basis of total weight of the curable basecoat composition, and preferably about 9.3 to about 100 weight percent.
• the curable basecoat composition further comprises at least one additive selected from the group consisting of pigments, plasticizers, fillers, adhesion promoters, solvents and mixtures thereof.
• Useful pigments include carbon black or metal oxides such as iron oxide and titanium dioxide. Generally, the pigment comprises about 3 to about
• the basecoating composition 6 weight percent of the total weight of the basecoating composition.
• the elastomeric coating composition is a two-part system, different colored pigments are added to each part in order to facilitate homogeneous mixing.
• Useful plasticizers include hydrogenated terphenyl and di- or tri- isodecylphthalate.
• the plasticizer is present in the basecoating composition in an amount ranging from about 0 to 5 weight percent of the total basecoating composition weight.
• Useful fillers include carbon black, calcium carbonate, titanium dioxide and fumed silica.
• the filler is present in the basecoating composition in an amount ranging from about 20 to 30 weight percent of the total basecoating composition weight.
• An adhesion promoter can be included in the basecoating composition to facilitate bonding to the substrate.
• Useful adhesion promoters include silanes, phenolics, titanates and epoxies.
• the adhesion promoter is present in the basecoating composition in an amount ranging from about 2 to 5 weight percent of the total basecoating composition weight.
• a solvent can be added to the basecoating composition to lower the viscosity of the composition and facilitate spray application.
• Useful solvents include methyl ethyl ketone, toluene and propylene glycol methyl ether acetate.
• the amount of solvent in the basecoating composition can range from about 20 to 30 weight percent based upon the total weight of the basecoating composition.
• the elastomeric basecoat has a tensile strength ranging from about 50 to about 600 pounds per square inch and percent elongation ranging from about 50% to about 800% at a coating thickness of 50 mils (1.27 mm) measured according to ASTM-D-412-617, which is incorporated herein by reference.
• tensile strength means the maximum resistance to deformation of a material based upon the undeformed area of the material as measured by ASTM-D-412-617.
• elongation means the maximum permanent strain prior to fracture of a material as measured by ASTM-D-412-617.
• the elastomeric basecoat has a fuel resistance such that it swells less than 50% by volume when exposed to Jet Reference Fluid (JRF) for two weeks at 140°F (60°C).
• JRF Jet Reference Fluid
• JRF is a mixture by volume of about 30% toluene
• the elastomeric basecoat be hydrolytically stable, i.e., it retains at least 40% of its original tensile strength and elongation after one month in water at 158°F (70°C).
• the basecoating composition is preferably applied to the surface of the substrate by conventional application techniques such as spraying, brushing, roller or conventional fill and drain techniques which are well known to those skilled in the art.
• the basecoating composition is applied to the substrate to provide a layer having a dried thickness ranging from about 3 to about 30 mils
• the basecoat thickness can be formed through a single application or multiple applications of the basecoating composition. In the instance where a base elastomeric coating thickness is built up through multiple applications, curing is optionally induced prior to application of a further layer. Preferably, a base elastomeric coating is applied through a single application.
• the basecoating composition can be cured in air at a temperature (preferably between about 10-100°C) prior to application of the topcoating composition.
• the substrate to be coated by the present invention can be formed from one or more polymeric, composite or metallic materials or combinations thereof.
• Useful metallic materials include aluminum, steel, titanium, and alloys thereof.
• Useful polymeric materials include polyurethane, nitrile or buna "N" rubbers and fiber composites. It is appreciated that the composite coating of the present invention can be applied to planar as well as complex geometric substrates. While the description of the present invention is directed toward rigid or flexible fuel storage containers, it is appreciated that the present invention has utility in coating a variety of substrates including joints in construction, pavement, aerospace applications as well as coating a variety of substrates including electrical wire, hoses, storage tanks, marine vessels and fuel transmission pipelines.
• the substrate surface can be cleaned to remove extraneous grease and debris before application of the basecoating composition.
• the present invention can be utilized without fazing the existing surface sealant.
• the basecoating composition is applied directly to the substrate, it is appreciated that an intermediate layer or primer coating between the bottom surface of the basecoating composition layer and the substrate is optionally employed.
• An intermediate layer or primer coating when present functions as an adhesion promoter between the elastomeric basecoat and the substrate.
• Useful intermediate layer coating materials optionally include PR-148, PR-1826, PR-182 and PR-1861 which are titanate-, epoxy-, silane- and epoxy-based primers, respectively, which are commercially available from PRC-DeSoto.
• the topcoating composition is applied over the at least partially cured basecoat.
• the topcoat is different from the basecoat, i.e., it contains at least one component which is chemically different from the components of the basecoat or at least one component which is present in a different amount than the same component which is present in the basecoat.
• the topcoat is preferably an elastomeric coating and has a higher tensile strength and/or percent elongation compared to the basecoat as determined according to ASTM D-412-617, with a flow out prepared of each material separately for testing.
• the topcoat has a tensile strength ranging from about 1000 to about 3000 pounds per square inch (70-120 kg/cm 2 ) and percent elongation ranging from about 500% to about 1000% at a coating thickness of 50 mils (1.27 mm).
• the top coat tensile strength is more than 100% higher than a comparable value of the base elastomeric coating.
• the basecoat preferably will fail thereby allowing the topcoat layer to flex and elongate while maintaining the integrity of the fuel seal.
• the topcoat is formed from a curable topcoat composition comprising one or more polythioether materials such as are described in detail above for the polymeric material of the basecoating composition.
• the polythioether material is liquid at ambient temperature and pressure.
• Useful polythioether materials include PERMAPOL P-3 and 855 polymers which are commercially available from PRC-DeSoto International.
• the polythioether material comprises about 40 to about 60 weight percent of the curable topcoat composition on a basis of total weight of the curable topcoat composition.
• the curable topcoat composition further comprises one or more curing agents. Suitable curing agents include those discussed above as curing agents for the elastomeric basecoat.
• the curing agent comprises about 2 to about 3 weight percent of the curable topcoat composition on a basis of total weight of the curable topcoat composition.
• the polythioether material cures in the presence of the curing agent in ambient air.
• the curable topcoat composition can further comprise one or more additives such as pigments, plasticizers, fillers, adhesion promoters, solvents and mixtures thereof.
• additives such as pigments, plasticizers, fillers, adhesion promoters, solvents and mixtures thereof.
• useful additives include those discussed above as additives for the elastomeric basecoat in similar amounts.
• the topcoat preferably further comprises a first pigment and the basecoat a second, differently colored pigment thereby imparting a different coloration to the topcoat as compared to the elastomeric basecoat to facilitate complete coverage thereof by the top coat.
• the top coat is applied to the laminate by spray, brush, roller or by conventional fill and drain techniques to a dry thickness of about 10 (0.25 mm) to about 30 mils (0.76 mm), and preferably about 10 (0.25 mm) to about 20 mils (0.5 mm).
• the top coat can be moisture or ambient or thermally cured, with the cure temperature preferably ranging from about 10°C and 100°C.
• the multi-component composite coating also can further comprise one or more overcoats applied over at least a portion of the topcoat.
• Suitable overcoats can include paint and primer.
• a multi-component composite coating which comprises an elastomeric basecoat formed from a curable basecoat composition deposited upon a surface of a substrate.
• the curable basecoat composition comprises one or more polymeric materials selected from the group consisting of polyurethanes, polysulfides, polythioethers, copolymers and mixtures thereof.
• a topcoat is applied over the basecoat, the topcoat being different from the basecoat and having a higher tensile strength and percent elongation than the elastomeric basecoat.
• the multi-component composite coatings of the present invention provide coatings and sealants which are useful for inhibiting leaks of liquids from substrates or joints between two substrates. If a basecoat of the present invention experienced loss of adhesion, for example through corrosion, poor application or impact damage, the lower tensile strength and lower elongation cured elastomeric basecoat preferably would fail before the higher tensile strength and higher elongation top coat, thereby maintaining the integrity of the overall coating and preventing exposure to the underlying substrate.
• the present invention can render a fuel container more flexible and vibration resistant because the cured elastomeric basecoat can absorb the majority of stresses associated with expansion and contraction encountered during operation of the aircraft.
• the present invention is useful for resealing aging aircraft fuel tanks since aged sealants can be recoated with the multi-component composite coating to seal existing leaks without fazing the existing sealant therefrom. Instead, simple abrasion and optimal solvent cleaning renders an existing sealant amenable to receiving a composite coating according to the present invention.
• Example Epoxy/graphite composite panels 6 in. x 6 in. x 0.084 in. (15.24 x 15.24 x 0.21 cm) (Hercules AW193-PW/3501-6S cured at 177°C and having a fiber volume range from 49.2 to 50.2%) were cleaned with methyl ethyl ketone
• a basecoat layer was formed upon the surface of the cleaned and conditioned panels by applying the following two-component polysulfide- containing basecoating composition as received:
• Plasticizer 2 29%
• the ratio of Component A to Component B was 9.3:100 on a total weight basis.
• the basecoating composition was applied by spraying onto the graphite panels and allowed to cure at ambient conditions (25°C ⁇ 5°C) for 6 hours to a dry thickness of 0.015 inch (0.38 mm).
• the cured basecoat had a tensile strength of 350 pounds per square inch (24.7 kg/cm 2 ) and 250% elongation as measured according to ASTM-D-412-617.
• Talc-IT-3X talc which is commercially available from R & T Vanderbilt.
• a topcoat composition was sprayed over the basecoat.
• the components of the topcoating composition are given below:
• the ratio of component A to component B was 90:100 on a total weight basis.
• the topcoat was applied by spraying to a dry thickness of about 0.035 inches (1.14 mm) and cured at ambient conditions (25°C ⁇ 5°C) for about 168 hours.
• the topcoat had a tensile strength of more than 1800 psi (127 kg cm 2 ) and elongation 900%, using the topcoat material cast alone to a thickness of 0.05 in. (0.0127 mm). These values were greater than that of the basecoat (350 PSI tensile strength and 250% elongation) as measured according to ASTM-D- 412-617.
• EMERY 1202 which is commercially available from Henkel Chemicals.
• Test specimens were machined to 15.2 cm 2 and were impacted at 1, 2, 4, 8 and 12 foot-pounds. A minimum of three test panels were impacted at each condition and then each panel was mounted in the jig.
• JRF Type Nil jet reference fuel
• Test panels prepared as above and having an overall coating thickness of 0.045 inches (1.14 mm) were tested for fuel permeability after impact damage.
• the average test results of 3 panels are given in Table 1 below.
• the composite basecoating as described above was applied to aluminum panels 6 in. x 6 in. x 0.04 in. (15.24 x 15.24 x 0.1 cm) (Alloy 7075 treated per MLL-S-5541) at 0.01 in. (0.25 mm) dry thickness, after cleaning with MEK and priming with PR-148. After the basecoat was cured for 6 hours, a topcoat as described above was applied at 0.035 in. (0.89 mm) dry thickness. After the topcoat was cured for 168 hours at 75°F (24°C), these panels were tested for fuel permeability after impact damage. The results thus obtained are shown in Table 2.

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• 2000
  • 2000-05-19 MX MXPA01011927A patent/MXPA01011927A/es unknown
  • 2000-05-19 CA CA002374408A patent/CA2374408A1/en not_active Abandoned
  • 2000-05-19 AU AU50305/00A patent/AU5030500A/en not_active Abandoned
  • 2000-05-19 JP JP2000619992A patent/JP2003500503A/ja active Pending
  • 2000-05-19 CN CN00807902A patent/CN1354765A/zh active Pending
  • 2000-05-19 KR KR1020017014718A patent/KR20020015690A/ko not_active Application Discontinuation
  • 2000-05-19 WO PCT/US2000/013806 patent/WO2000071605A1/en not_active Application Discontinuation
  • 2000-05-19 EP EP00932609A patent/EP1183300A1/de not_active Withdrawn
  • 2000-05-19 BR BR0010729-8A patent/BR0010729A/pt not_active Application Discontinuation

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