Coating compositions comprising magnesium oxide and a lithium compound

Abstract

Disclosed herein are coating compositions comprising: (a) a film-forming binder; (b) magnesium oxide; and (c) a lithium compound in an amount of 0.01% by weight to less than 1% by weight based on total solids weight, wherein the lithium compound has a solubility constant (Ksp) in water at 25°C of greater than 0.05. Also disclosed are methods for coating a substrate. Also disclosed are coated substrates.

Description

COATING COMPOSITIONS COMPRISING MAGNESIUM OXIDE AND A LITHIUMCOMPOUNDCROSS-REFERENCE

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 619,978 filed on January 11, 2024, entitled “Compositions Containing Magnesium Oxide Particles and Lithium Salts,” incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure is directed to coating compositions comprising magnesium oxide.BACKGROUND

[0003] Coating compositions comprising film-forming binders have been widely applied to, for example, appliances, automobiles, aircrafts, and the like. Such coatings may also comprise corrosion inhibitors that provide corrosion resistance.SUMMARY

[0004] Disclosed herein are coating compositions comprising: (a) a film-forming binder;(b) magnesium oxide; and (c) a lithium compound in an amount of 0.01% by weight to less than 1 % by weight based on total solids weight, wherein the lithium compound has a solubility constant (Ksp) in water at 25°C of greater than 0.05.

[0005] Also disclosed are methods for coating a substrate comprising applying any of the coating compositions disclosed herein to a surface of the substrate to form a first coating.

[0006] Also disclosed are substrates comprising a coating on a surface thereof, formed from any of the coating compositions disclosed herein.DETAILED DESCRIPTION

[0007] The present disclosure is directed to a coating composition comprising, or consisting essentially of, or consisting of, (a) a film-forming binder, (b) a magnesium oxide, and(c) a lithium compound in an amount of 0.01% by weight to less than 1% by weight based on total solids weight, wherein the lithium compound has a solubility constant (Ksp) in water at 25°C of greater than 0.05.Film-Forming Binder

[0008] A “film-forming binder” is one that, upon hardening and / or curing, can form a continuous film on a surface. The film-forming binder may comprise a film-forming resin such as an organic resin. The film-forming binder may further comprise a curing agent reactive with the film-forming resin.

[0009] The film-forming resin is not limited and may comprise one or more organic polymers, such as acrylic polymers, polyesters, polyurethanes, polyamides, polyethers, poly thioethers, polythioesters, polythiols, polyenes, polyols, polysilanes, polysiloxanes, fluoropolymers, polycarbonates, and / or epoxy resins. Generally, these compounds, which need not be polymeric, can be made by any method known to those skilled in the art. The filmforming resin may comprise a functional group, such as a carboxylic acid group, an amine group, an epoxide group, a hydroxyl group, a thiol group, a carbamate group, an amide group, a urea group, a (meth) acrylate group, a styrenic group, a vinyl group, an allyl group, an aldehyde group, an acetoacetate group, a hydrazide group, a cyclic carbonate group, a maleic acid group, and / or an anhydride group. The functional group on the film- forming resin may be selected so as to be reactive with a functional group on the curing agent or to be self-crosslinking.

[0010] The film-forming resin may further comprise an inorganic film-forming resin, such as a silicone resin.

[0011] When present, the curing agent may be selected so as to have reactivity with the film-forming resin. The curing agent may comprise a molecule or functional group that may react with a reactive group, such as an active hydrogen group, on the film-forming resin to effectuate cure of the coating composition to form a coating.

[0012] Examples of a suitable curing agent include an aminoplast, a phenoplast, a polyisocyanate, including a blocked isocyanate, a polyepoxide, a beta-hydroxyalkylamide, a polyacid, an organometallic acid-functional material, a polyamine, a polyamide, a polysulfide, a polythiol, a polyene such as a polyacrylate, a polyol, and / or a polysilane. Suitable commercially available aminoplast curing agents include those from ALLNEX, such as CYMEL 303, CYMEL 1130, CYMEL 1156, and the like.

[0013] In examples, the coating composition may comprise a film-forming binder comprising an epoxy-containing film-forming resin and a curing agent comprising an amine curing agent. Suitable examples of the epoxy-containing film-forming resin include an aromaticor an aliphatic epoxy resin, such as a resin based on Bisphenol A, diglycidyl ethers of Bisphenol A, Bisphenol F, glycerol, novolac, and the like, or epoxy modified polymers, such as epoxy modified acrylic. Suitable commercially available epoxy film-forming resins include EPON 828, EPON 862, EPON 1001, and / or EPON 8111, all available from Westlake Epoxy, and D.E.N. 431, available from Olin.

[0014] Suitable commercially available amine curing agents include those available under the trade name ANCAMINE, such as ANCAMINE 2432, ANCAMIDE 2569, ANCAMINE 2672, ANCAMINE 2686, and ANCAMINE K-54, all available from Evonik, and polyether functional amines such as those available under the trade name JEFFAMINE, such as JEFFAMINE D2000, available from Huntsman Corporation.

[0015] In other examples, the film- forming resin may comprise a hydroxyl functional group, such as a hydroxy functional polyester, a hydroxy functional polyurethane, a hydroxy functional acrylic, and the like.

[0016] The coating composition may comprise the film-forming binder in an amount of at least 20% by weight based on total solids weight of the coating composition, such as at least 30% by weight. The coating composition may comprise the film-forming binder in an amount of no more than 90% by weight based on total solids weight of the coating composition, such as no more than 80% by weight. The coating composition may comprise the film-forming binder in an amount of 20% by weight to 90% by weight based on total solids weight of the coating composition, such as 30% by weight to 80% by weight.Magnesium Oxide

[0017] The coating compositions of the present disclosure further comprises magnesium oxide (MgO).

[0018] The MgO may comprise nano- sized MgO and / or micron- sized MgO. The particle size may be reported as average particle size by the manufacturer, or optionally, the number average particle size may be determined, for example, by visually examining a micrograph of a transmission electron microscopy (“TEM”) image, as described below.

[0019] The MgO may comprise a micron sized powder, or a dispersion thereof, having a number average particle size of at least 0.5 micron, such as at least 1 micron. The MgO may comprise a micron sized powder, or dispersion thereof, having a number average particle size of no more than 50 microns, such as no more than 30 microns. The MgO may comprise a micronsized powder, or dispersion thereof, having a number average particle size of 0.5 microns to 50 microns, such as 1 micron to 30 microns.

[0020] Alternatively, or in addition, the MgO may comprise a nano sized powder, or dispersions thereof. The MgO may comprise a nano sized powder having a number average particle size of at least 10 nm. The MgO may comprise a nano sized powder having a number average particle size of no more than 499 nm, such as no more than 100 nm. The MgO may comprise a nano sized powder having a number average particle size of 10 nm to 499 nm, such as 10 nm to 100 nm.

[0021] Number average particle size reported herein may be determined by visually examining a micrograph of a transmission electron microscopy (“TEM”) image, measuring the diameter of the particles in the image, and calculating the average primary particle size of the measured particles based on magnification of the TEM image. One of ordinary skill in the art will understand how to prepare such a TEM image and determine the primary particle size based on the magnification. The primary particle size of a particle refers to the smallest diameter sphere that will completely enclose the particle. As used herein, the term “primary particle size” refers to the size of an individual particle as opposed to an agglomeration of two or more individual particles.

[0022] Particle size as reported herein refers to the MgO particle size prior to incorporation into the coating composition. Various coating preparation methods may result in the MgO particles agglomerating, which could increase average particle size, or shearing or other action that can reduce average particle size. MgO particles are commercially available from a number of sources, such as NANO-MgO from U.S. Research Nanomaterials, Inc. (TX, USA), such as MAGLITE Y from The Hallstar Company (IL, USA), and the like.

[0023] The MgO may comprise ultrafine MgO particles. As used herein, the term “ultrafine” particles refers to particles that have a B.E.T. specific surface area of at least 10 square meters per gram (m2 / g), such as 30 m2 / g to 500 m2 / g, such as 30 m2 / g to 100 m2 / g, such as 40 m / g to 80 m / g, such as 40 m / g to 60 m_ / g, such as 80 nr / g to 250 m_ / g. As used herein, “B.E.T. specific surface area” refers to a specific surface area determined by nitrogen adsorption according to the ASTM D3663-78 standard based on the Brunauer-Emmett-Teller method described in the periodical “The Journal of the American Chemical Society,” 60, 309 (1938).

[0024] The MgO may comprise MgO particles having a calculated equivalent spherical diameter of no more than 200 nm, such as no more than 100 nm, such as 5 nm to 50 nm. As will be understood by those skilled in the ait, a calculated equivalent spherical diameter may be determined from the B.E.T. specific surface area according to the equation:Diameter (nm) = 6000(B.E.T. (m2 / g))(density (g / cm3))

[0025] The shape (or morphology) of the MgO particles may vary. For example, the MgO particles may comprise particles having generally spherical morphologies and / or the MgO particles may be cubic, platy, polyhedric, or acicular (elongated or fibrous). The particles may be covered completely in a polymeric gel, not covered at all in a polymeric gel, or covered partially with a polymeric gel. Covered partially with a polymeric gel means that at least some portion of the particle has a polymeric gel deposited thereon, which, for example, may be covalently bonded to the particle or merely associated with the particle.

[0026] The MgO may comprise one or more different types of MgO particles. For example, the MgO may comprise MgO nanosized particles and MgO micron sized particles.

[0027] The MgO acts as a corrosion inhibitor that may provide at least some corrosion inhibition to the underlying substrate upon which the coating composition is applied. As used herein, a “corrosion inhibitor” refers to a compound that inhibits the corrosion of metals. The effectiveness of the corrosion inhibitor in a cured coating in preventing corrosion of the substrate upon which the coating composition is applied and cured may be demonstrated, for example, by salt spray corrosion testing according to ASTM B117-19. Whether the corrosion inhibitor improves corrosion resistance may be determined by testing the ability of the cured coating comprising the corrosion inhibitor to improve the corrosion performance as measured by one or more methods, such as through reduced substrate pitting, scribe corrosion, scribe shine, and / or reduction in the number and / or size of blisters present in the coating adjacent to the scribe, when compared to a similar composition that does not include the corrosion inhibitor.

[0028] The coating composition may comprise the magnesium oxide in an amount of at least 6% by weight based on total solids weight of the coating composition, such as at least 20% by weight. The coating composition may comprise the magnesium oxide in an amount of no more than 60% by weight based on total solids weight of the coating composition, such as no more than 50% by weight. The coating composition may comprise the magnesium oxide in anamount of 6% by weight to 60% by weight based on total solids weight of the coating composition, such as 20% by weight to 50% by weight.Lithium Compound

[0029] The disclosed coating compositions comprise a lithium compound. The lithium compound may comprise a lithium salt, such as lithium hydroxide, lithium sulfate, lithium citrate, lithium acetate, lithium tartrate, and / or lithium nitrate. The lithium compound may comprise lithium oxide, lithium dihydrogen phosphate, and / or lithium oxalate.

[0030] The lithium compound may have a solubility constant (Ksp) in water at 25°C of greater than 0.05, such as at least 1, such as at least 5, such as at least 10, such as at least 20. The lithium compound may have a Ksp in water at 25°C of no more than 1,000, such as no more than 500. The lithium compound may have a Ksp in water at 25°C of greater than 0.05 to 1,000, such as 1 to 1,000, such as 5 to 1,000, such as 10 to 1,000, such as 20 to 500. As known to those skilled in the art, the solubility constant may be calculated using the equilibrium concentrations of the ions of the lithium salt in a saturated aqueous solution using the equation:A table of Ksp values may also be found in the CRC Handbook of Chemistry and Physics, 105thEdition, Chapter 4, “Solubility Product Constants of Inorganic Salts.”

[0031] The lithium compound may have a water solubility at 20°C of greater than 3g / 100 ml, such as greater than 5 g / 100 ml, such as greater than 8 g / 100 ml, such as greater than 10 g / 100 ml, such as 12 g / 100 ml or greater.

[0032] The lithium compound may have a water solubility at 30°C of greater than 3 g / 100 ml, such as greater than 5 g / 100 ml, such as greater than 8 g / 100 ml, such as greater than 10 g / 100 ml, such as 12 g / 100 ml or greater.

[0033] Exemplary Ksp and water solubility values for lithium compounds are provided in Table I.Table I

[0034] The lithium compound may be present in the composition in an amount of at least 0.01% by weight based on total solids weight of the composition, such as at least 0.05% by weight. The lithium compound may be present in the composition in an amount of less than 1% by weight based on total solids weight of the composition, such as no more than 0.5% by weight. The lithium compound may be present in the composition in an amount of 0.01% by weight to less than 1% by weight based on total solids weight of the composition, such as 0.05% by weight to 0.5% by weight.

[0035] The lithium compound may be present in the coating composition in an amount of at least 0.01% by volume based on total solids volume of the coating composition, such as at least 0.05% by volume. The lithium compound may be present in the coating composition in an amount of less than 1% by volume based on total solids volume of the coating composition, such as no more than 0.5% by volume. The lithium compound may be present in the coating composition in an amount of 0.01% by volume to less than 1% by volume based on total solids volume of the coating composition, such as 0.05% by volume to 0.5% by volume.Optional Components

[0036] The coating composition may further comprise a corrosion inhibitor in addition to the MgO and the lithium compound.

[0037] The addition corrosion inhibitor may comprise morpholines, monosulfides, disulfides, piperazines, azoles, oxazoles, thiazoles, thiazolines, imidazoles, diazoles, indolizines, triazines, tetrazoles, and / or tolutriazole. Non-limiting examples of such additional corrosion inhibitors include but are not limited to 4-phenyl-thiomorpholine-3, 5-dione, 2-morpholino-4- phenylthiazole, 4-(4-phenyl-2-thiazolyl)-morpholine, 4-(2-thienylmethyl)morpholine, 4-(4- morpholinylacetyl)morpholine, 4-(4-morpholinyldisulfany l)morpholine, 2,6-dimethyl-4- [(3- methyl-2-thienyl)carbonyl]morpholine, 2,6-dimethyl-4-(2-pyrazinylcarbonyl)morpholine, 4-[(3- methyl-2-thienyl)methyl]morpholine, 4-{ [(4-morpholinylmethyl)sulfanyl]methyl]morpholine, 4- [2-(5-ethyl-2-pyridinyl)ethyl]morpholine, 4- [4-(4-morpholinyl)butyl] morpholine, 4-(5-methoxy- 2-methyl-4-pyrimidinyl)morpholine, 4-(5-methyl-2-pyrimidinyl)morpholine, 4-[(l,3-dimethyl- 1 H-pyrazol-5 -yl)carbonyl] morpholine, 4- [( 1 -methyl- 1 H-pyrazol-5-yl)carbonyl]morpholine, 4- [(3,5-dimethyl-lH-pyrazol-l-yl)carbonyl]morpholine, 4-{ [(3-{ [2-(4-morpholinyl)-2- oxoethyl] sulfanyl } - 1 , 2, 4-thiadiazol-5 -yl)sulfanyl] acetyl } morpholine, 4-morpholinopyridine,morpholin-4-yl morpholine-4-carbodithioate (commercially available as Cure Rite 18 from AkroChcm, Inc.), tctramcthylthiuram monosulfidc (commercially available as VANAX TMTM from Vanderbilt Chemicals, LLC), l-Boc-(4-benzyl)piperazine, tert-butyl 4-(l-benzylpiperidin- 4-yl)piperazine- 1 -carboxylate, piperazine- 1 ,4-dicarbothioic acid bis-phenylamide, 1 ,4-bis(2-(2- pyridinyl)ethyl)piperazine, 1 ,4-bis-(2-benzyloxy-ethyl)-piperazine, 1 ,4-di(2-furoyl)piperazine, 1 - ethyl-4-(2-thienylsulfonyl)piperazine, l-isopropyl-4-(2-thienylcarbonyl)piperazine, l-methyl-4- [(3-methyl-2-thienyl)methyl]piperazine, l-methyl-4-(3-thienylmethyl)piperazine, l-isopropyl-4- [( 1 -methyl- lh-pyrrol-2-yl)methy l]piperazine, 1 ,4-di-tert-butyl piperazine- 1 ,4-dicarboxy late, 1 - methyl-benzotriazole, 1 -methyl- 1 ,2,3-triazole, 1 -phenyl- 1 ,2,3-triazole, 4-methyl-2-phenyl- 1,2,3- triazole, l-benzyl-l,2,3-triazole, l-benzamido-4-methyl-l,2,3-triazole, 1 -methyl- 1, 2, 4-triazole, 1 ,3-diphenyl- 1 ,2, 4-triazole, 1 -phenyl- 1 ,2,4-triazole-5-one, 1 -methyl-benzotriazole, methyl- 1 - benzotriazolecarboxylate, benzothiazole, 1 -phenyl-4-methylimidazole, and / or l-(p-tolyl)-4- methylimidazole.

[0038] The optional additional corrosion inhibitor may comprise at least one heterocyclic ring comprising a ring structure of at least 5 atoms connected via covalent bonds, wherein the ring comprises carrion and at least one heteroatom of sulfur or nitrogen. The heterocyclic ring may optionally further comprise at least one heteroatom of oxygen or phosphorous. The additional corrosion inhibitor may optionally further comprise at least one additional heteroatom of oxygen, nitrogen, sulfur, phosphorous, or an aromatic ring bound directly or indirectly to the heterocyclic ring.

[0039] The coating composition may comprise still other optional additional corrosion inhibitors, such as metallate anion ion-paired through Coulomb attraction to a pyridine, a pyrrole, and / or an imidazole. As used herein, the term “metallate anion” refers to metalates of molybdenum, tungsten, vanadium, zirconium, and / or chromium.

[0040] The additional corrosion inhibitors may comprise other compounds comprising lithium, such as lithium silicates, that have a Ksp lower than 0.05, rare earth corrosion inhibitors such as compounds comprising yttrium, cerium, and / or conventional corrosion inhibiting particles, such as but not limited to iron phosphate, zinc phosphate, such as zinc hydroxyl phosphate (commercially available from Elementis as NALZIN), calcium ion-exchanged silica (commercially available from Gare & Co. as SHIELDEX AC3 and / or SHIELDEX C30),colloidal silica, synthetic amorphous silica, and molybdates, such as calcium molybdate, zinc molybdate, barium molybdate, and / or strontium molybdate.

[0041] The coating composition may comprise the additional corrosion inhibitor in an amount of at least 0.05% by weight based on total solids weight of the coating composition, such as at least 0.1% by weight. The coating composition may comprise the additional corrosion inhibitor in an amount of no more than 5% by weight based on total solids weight of the coating composition, such as no more than 4% by weight. The coating composition may comprise the additional corrosion inhibitor in an amount of 0.05% by weight to 5% by weight based on total solids weight of the coating composition, such as 0.1% by weight to 4% by weight.

[0042] Alternatively, the coating composition may be substantially free, essentially free, or completely free of a corrosion inhibitor in addition to the MgO and the lithium compound.

[0043] The coating composition may comprise other ingredients commonly used in such compositions, examples of which include additional polymers, water, solvents, such as organic solvents, colorants, fillers including clays, inorganic minerals, abrasion-resistant particles, antioxidants, hindered amine light stabilizers, UV light absorbers and stabilizers, surfactants, flow and surface control agents, thixotropic agents, reactive diluents, driers, catalysts, reaction inhibitors, adhesion promoting materials, such as acids and acid derivatives, phosphatized epoxy, silanes, such as epoxy silanes or amine silanes, and other customary additives known to those skilled in the ait. As used herein, “colorants” refers to any substance that imparts color and / or other opacity and / or other visual effect to the composition.

[0044] The coating composition may be substantially free, essentially free, or completely free of molybdenum. The coating composition may be substantially free, essentially free, or completely free of a molybdenum containing lithium salt, such as lithium molybdate.

[0045] The coating composition may be substantially free, essentially free, or completely free of hexavalent chromium.

[0046] The coating composition may be substantially free, essentially free, or completely free of a zinc salt of 2,5-dimercapto-l,3,4-thiadiazole (DMTD).Compositions and Coatings

[0047] The coating compositions of the present disclosure may be liquid coating compositions at ambient conditions, such as solvent-based coating compositions (wherein greaterthan 50% of the total solvent is organic solvent), or water-hased coating compositions (wherein 50% or greater of the total solvent is water) or may be powder coating compositions.

[0048] The coating compositions disclosed herein may be thermoset or thermoplastic. A “thermoset” composition irreversibly hardens upon curing. A “thermoplastic” composition reversibly hardens upon curing. That is, following cure, a thermoplastic composition may be heated to soften the cured composition, then cooled to reharden.

[0049] The present compositions may be either one component (“IK”) or multicomponent compositions, such as two component (“2K”) or more. As used herein, a “one component” composition refers to a composition wherein all the components are maintained in the same container after manufacture, during storage, etc. A IK composition can be applied to a substrate and cured by any conventional means, such as by heating, forced air, and the like. As used herein, a “multi-component” composition refers to a composition wherein all the components are maintained separately until just prior to application. For example, the present compositions might be packaged as a 2K system, with the resin component in a first component (A) and a curing agent component in a second component (B). All other components used in the coating composition may be present in component (A), component (B), and or a third or higher component (C).

[0050] Coating compositions of the present disclosure may be prepared using any suitable method, such as manual stirring or air or electric mixing, such as with blade stirrers, or static mixing, magnetic stir bars, and the like. The present coating compositions may be formulated as a primer, a basecoat, a topcoat, a sealant, a gap filler, and / or an adhesive.

[0051] Further disclosed herein are coatings deposited from any of the coating compositions disclosed herein. Upon cure, the coating may have any desired dry film thickness (“DFT”). The coatings formed from any of the coating compositions disclosed herein may impart corrosion inhibition to a metallic substrate. For example, the coatings, when cured to a DFT of 0.5 mils to 10 mils, impart excellent corrosion resistance and adhesion. Coatings deposited from one of the coating compositions disclosed herein impart improved corrosion resistance over coating compositions comprising either MgO or a lithium compound comprising a Kspof greater than 0.05 in an amount of 0.01% by weight to less than 1% by weight based on total solids weight of the coating composition, while maintaining pencil hairiness and adhesion performance. This was a surprising and unexpected result. It was also surprisingly discoveredthat lower amounts of lithium compound were required to achieve the desired adhesion and corrosion performance as the solubility of the lithium compound increased

[0052] Coatings formed from the coating compositions disclosed herein exhibit:(a) no pitting from dis-bonded corrosion pitting testing;(b) a pencil hardness rating of 4H;(c) a pencil hardness rating after SKYDROL immersion of 4H;(d) a dry adhesion rating of 5B;(e) a wet adhesion rating of 5B;(f) a scribe corrosion rating of less than 20; a scribe shine rating of at least 30; less than 4 scribe blisters; 0 face blisters; and / or a maximum scribe blister size of less than 3.0 mm, tested according to ASTM B117-19 on bare 2024-T3 aluminum panels after 1000 hours of salt spray;(g) a scribe corrosion rating less than 15; a scribe shine rating of 70 or greater; 10 or less scribe blisters; 8 or less face blisters; and / or a maximum scribe blister size of 3.5 or less, tested according to ASTM B117-19 on clad 2024-T3 aluminum panels after 1000 hours of salt spray;(h) a scribe corrosion rating of 20 or less; a scribe shine rating of 0; 1 or less scribe blisters; 0 face blisters; and / or a maximum scribe blister size of 3.8 or less, tested according to ASTM B117-19 on bare 2024-T3 aluminum panels after 3000 hours of salt spray; and / or(i) a scribe corrosion rating of 40 or less; a scribe shine rating of 0; 5 or less scribe blisters; 0 face blisters; and / or a maximum scribe blister size of less than 6, tested according to ASTM B117-19 on clad 2024-T3 aluminum panels after 3000 hours of salt spray.Methods

[0053] The present disclosure is also directed to a method for coating a substrate comprising applying to at least a portion of the substrate a first coating composition comprising the coating composition of the present disclosure to form a first coating, and optionally applying one or more additional coatings to at least a portion of the first coating, wherein the one or more additional coatings is applied from a coating composition that is the same or different than the coating composition of the present disclosure and / or the one or more additional coatings is applied from a coating composition comprising a silicone modified polyester coating composition, a fluoropolymer coating composition, and / or a polyurethane coating composition.

[0054] The one or more additional coatings may be applied over an uncured coating composition of the present disclosure, an at least partially cured coating composition of the present disclosure, or a fully cured coating composition of the present disclosure.

[0055] After application to the substrate(s), the composition may be cured. For example, the composition may be allowed to cure at room temperature, and for any desired time period sufficient to at least partially cure the composition on the substrate(s), such as for 1 to 2 hours, prior to application of an additional same or different coating layer. In another example, the composition may be allowed to fully cure at room temperature, and for any desired time period, such as for two weeks. The composition may be cured to form a coating on the substrate surface under ambient conditions or slightly thermal conditions. The coating may be, for example, a primer, a basecoat, a topcoat, a sealant, a gap filler, or an adhesive.

[0056] The present disclosure is further directed to a method for using the coating composition of the present disclosure to form a coating on at least a portion of a substrate, comprising depositing the coating composition onto the substrate. The coating compositions can be deposited onto or “applied to” substrates by any suitable method known to those skilled in the art. Examples include coil coating, spraying, such as electrostatic spraying, flow coating, spin coating, curtain coating, brushing, rolling, dipping, or by the use of a fluidized bed.

[0057] Once the coating composition is deposited onto the substrate, it can be dried or cured by any suitable means. Examples of such suitable curing techniques include curing at ambient conditions, elevated temperature, and / or exposure to actinic radiation. As used herein, “ambient” conditions refer to room temperature (20°C ± 5 °C) and humidity conditions (20% relative humidity to 80% relative humidity). As used herein, “elevated” temperatures refer to temperatures of 30°C or higher. Elevated temperatures may be achieved by baking in a thermal oven, induction heating, and / or infrared heating. The composition may be allowed to fully cure at room temperature and for any desired time period, such as for two weeks. Upon cure, a coating layer is formed on the substrate.Additive Manufacturing

[0058] The coating compositions of the present disclosure may be used in any suitable additive manufacturing technology, such as three-dimensional (3D) printing, extrusion, jetting, and binder jetting. Any suitable mixing, delivery, and 3D printing equipment known to those skilled in the art may be used.

[0059] Methods provided by the present disclosure include printing the composition on a fabricated part. Methods provided by the present disclosure include directly printing and / or manufacturing of pails or articles by additive manufacturing processes such as 3D printing. The entire part can be formed from one of the compositions disclosed herein and / or one or more surfaces of a part can be formed from a composition provided by the present disclosure. In addition, internal regions of a part can be formed from a composition provided by the present disclosure.Substrates

[0060] The present disclosure is further directed to substrates coated at least in part with a coating deposited from any of the coating compositions disclosed herein. Suitable substrates include metal substrates, such as flexible and rigid metal substrates, metal alloy substrates, and / or substrates that have been metallized, such as nickel-plated plastic. Additionally, substrates may comprise non-metal substrates, for example, polymeric materials, such as plastics including filled and unfilled thermoplastic or thermoset materials and / or composite materials such as, for example, plastic, fiberglass, and / or materials comprising carbon fibers and / or conductive carbon. Substrates may include two or more materials in any combination. For example, the substrate may comprise two different metals, or a metal and a metal alloy, or a metal and a metal alloy and one or more composite materials.

[0061] The coated substrate may comprise a three-dimensional component formed by an additive manufacturing process, such as a three-dimensional formed composite.

[0062] The metal or metal alloy may comprise, for example, cold rolled steel, hot rolled steel, steel coated with zinc metal, zinc compounds, or zinc alloys, such as electrogalvanized steel, hot-dipped galvanized steel, galvannealed steel, GALVANNEAL steel, nickel-plated steel, steel plated with zinc alloy, and stainless steel, such as martensitic, duplex, ferritic, austenitic, and / or precipitation hardened stainless steel. Steel substrates (such as cold rolled steel or any of the steel substrates listed above) coated with a weldable, zinc-rich or iron phosphide-rich organic coating are also suitable for use in the present disclosure. Such weldable coating compositions are disclosed in U.S. Patent Nos. 4,157,924 and 4,186,036, incorporated herein by reference.The substrate may comprise aluminum, aluminum alloys, zinc-aluminum alloys such as GALFAN, GALVALUME, aluminum plated steel, and aluminum alloy plated steel substrates. Non-limiting examples of aluminum alloys include the 1000, 2000, 3000, 4000, 5000, 6000, or7000 series, such as 2024, 2024-T3, 7075, 7075-T6, as well as clad aluminum alloys, such as 2024-T3 clad, and cast aluminum alloys, such as, for example, the A356 series. The substrate may comprise a magnesium alloy. Non-limiting examples of suitable magnesium alloys include those of the AZ31B, AZ91C, AM60B, or EV31A series. The substrate used in the present disclosure may also comprise other suitable non-ferrous metals such as titanium or copper, as well as alloys of these materials.

[0063] The substrate may comprise a multi-metal article. As used herein, the term “multi-metal article” refers to (1) an article that has at least one surface comprised of a first metal and at least one surface comprised of a second metal that is different from the first metal, (2) a first article that has at least one surface comprised of a first metal and a second article that has at least one surface comprised of a second metal that is different from the first metal, or (3) both (1) and (2). The substrate may comprise surfaces or parts of different substrate materials that are adjacent or joined together, such as, for example, a galvanic assembly.

[0064] Substrates comprising a coating layer deposited from the coating compositions of the present disclosure may be uncoated prior to a coating layer being deposited thereon.

[0065] Substrates comprising a coating layer deposited from the coating compositions of the present disclosure may comprise one or more additional layers over and / or under the layers; these multiple layers are referred to herein as a “multi-layer coating system” or “coating stack.” Additional layers may comprise an aluminum cladding layer, an anodized oxide layer, a conversion coating, a non-chromate treatment, and / or a pretreatment layer. The pretreatment layer may comprise, for example, a pretreatment layer such as those described in U.S. Patent Nos. 4,793,867 and 5,588,989, incorporated herein by reference, a zirconium containing pretreatment solution such as, for example, those described in U.S. Patent Nos. 7,749,368 and 8,673,091, incorporated herein by reference, a phosphate containing pretreatment solution (e.g., a zinc phosphate containing pretreatment solution), and / or a solgel, such as those comprising alkoxy-silanes, alkoxy-zirconates, and / or alkoxy-titanates. The coating composition of the present disclosure may be applied over at least a portion of the pretreated layer; one or more additional coating layers may be applied over at least a portion of the present coating layer. Additional coating layers may comprise primers, basecoats, color coats, monocoats, clear coats, and / or topcoats. Suitable additional coating layers include any of those known in the art, and each independently may be water-based, solvent-based, in solid particulate form (i.e., a powdercoating composition), or in the form of a powder slurry. The additional coating layers may each be cured independently, or optionally applied “wet-on-wet” and cured simultaneously. As used herein, “wet-on-wet” refers to a process wherein a coating, for example, a clear coat, is applied over a substantially uncured different coating, for example, a color coat, and both coatings are cured simultaneously. Different layers in the coatings stack may contain components that impart a desired property, visual effect, and / or color effect to the coating, such as corrosion inhibitors; conductive agents such as graphene, conductive carbon black, conductive polymers, or conductive additives; pigments such as those described in U.S. Patent No. 10,844,256 at 8: 18-43, the cited portions thereof incorporated herein by reference, or other chromatic pigments, and the like.

[0066] The substrate may be new (i.e. , newly constructed or fabricated) or it may be refurbished, such as in the case of refinishing or repairing a component of an automobile or aircraft.

[0067] The substrate may be in any form, such as a sheet, a foil, a laminate foil, a pad, a fabricated part, a component, and / or an article. The substrate may be in the shape of a cylinder, such as a pipe, including, for example, a cast iron pipe. The substrate may also comprise conductive or non-conductive substrates at least partially coated with a conductive coating. The conductive coating may comprise a conductive agent such as, for example, graphene, conductive carbon black, conductive polymers, and / or conductive additives.

[0068] The substrate may optionally be subjected to other treatments prior to coating. For example, the substrate may be cleaned, cleaned and deoxidized, anodized, acid pickled, plasma treated, laser treated, or ion vapor deposition (IVD) treated. The substrate may be abraded, such as wet or dry abraded with a pad, such as a 3M SCOTCH-BRITE pad.

[0069] Applications of the compositions disclosed herein are not limited. The coating compositions disclosed herein may be suitable for use in various industrial or transportation applications including appliance, coil, automotive applications, commercial transport applications, rail locomotive, marine applications, and / or aerospace applications. Suitable substrates for use in the present disclosure include those that are used in the form of sheets or coils, or in the assembly of appliances or of vehicular’ bodies (such as door, body panel, trunk deck lid, roof panel, hood, roof and / or stringers, rivets, landing gear components, and / or skins used on an aircraft), vehicular frames, vehicular parts, motorcycles, wheels, and industrialstructures and components. As used herein, “vehicle” or variations thereof includes all types of aircraft, spacecraft, watercraft, and ground vehicles. A vehicle may be an aerospace vehicle including aircraft such as airplanes, including private aircraft, and small, medium, or large commercial passenger, freight, civilian, and military aircraft; helicopters, including private, commercial, and military helicopters; or rockets and other spacecraft. A vehicle can include a ground vehicle, such as tanks, armored cars, trailers, cars, trucks, buses, vans, construction vehicles, golf carls, motorcycles, bicycles, trains, and railroad cars. A vehicle can also include watercraft such as, for example, ships, boats, and hovercraft. The coating composition may be utilized to coat surfaces and parts thereof. A pail may include multiple surfaces. A part may include a portion of a larger part, assembly, or apparatus. A portion of a part may be coated with the coating composition of the present disclosure, or the entire part may be coated. An “aircraft part” refers to any part used on any aircraft, internally or externally, and made of any substrate.Definitions

[0070] For purposes of this detailed description, it is to be understood that the disclosure may assume alternative variations and step sequences, except where expressly specified to the contrary.

[0071] The numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0072] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0073] As used herein, “including,” “containing,” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, ingredients, or method steps. As used herein, “consisting of’ is understood in the context of this application to exclude the presence of any unspecified element, ingredient, or method step. As used herein, “consisting essentially of’ is understood in the context of this application to includethe specified elements, materials, ingredients, or method steps “and those that do not materially affect the basic and novel charactcristic(s)” of what is being described.

[0074] In addition, in this application, the use of “or” means “and / or” unless specifically stated otherwise, even though “and / or” may be explicitly used in certain instances.

[0075] As used herein, the terms “on,” “onto,” “applied on,” “applied onto,” “formed on,” “deposited on,” “deposited onto,” and the like mean formed, overlaid, deposited, or provided on, but not necessarily in contact with, a substrate surface. For example, a composition “applied onto” a substrate surface does not preclude the presence of one or more other intervening coating of the same or different composition located between the composition and the substrate surface.

[0076] As used herein, a “coating composition” refers to a composition, e.g., a solution, mixture, or a dispersion, that is capable of producing a coating on a portion of a substrate surface.

[0077] As used herein, “coating” includes films, layers, and the like.

[0078] As used herein, “polymer” refers to prepolymers, oligomers, homopolymers, and copolymers.

[0079] As used herein, the terms “cure,” “cured,” “harden,” and the like, refer to the ability of at least a portion of the polymerizable and / or crosslinkable components to undergo a reaction. Curing of the coating composition occurs upon subjecting said composition to curing conditions (e.g., ambient temperature, elevated temperature, actinic radiation, etc.) leading to the reaction of at least a portion of the reactive functional groups on the components of the coating composition and resulting in the crosslinking of at least a portion of the components of the coating composition and formation of an at least partially cured coating layer.

[0080] As used herein, “substantially free” means that a particular material is not purposefully added to a mixture or composition, respectively, and is present only as an impurity in a trace amount of less than 0.001% by weight based on total solids weight of the mixture or composition, respectively. As used herein, unless indicated otherwise, the term “essentially free” means that a particular material is present only in an amount of less than 0.0001% by weight based on total solids weight of the mixture or composition, respectively. As used herein, unless indicated otherwise, the term “completely free” means that a mixture or composition,respectively, does not comprise a particular material, i.e., the mixture or composition comprises 0% by solids weight of such material.Aspects

[0081] In view of the foregoing description, the present disclosure relates to the following Aspects 1 to 67 without being limited thereto.

[0082] Aspect 1. A coating composition comprising:(a) a film-forming binder;(b) magnesium oxide; and(c) a lithium compound in an amount of 0.01% by weight to less than 1% by weight based on total solids weight; wherein the lithium compound has a solubility constant (Ksp) in water at 25°C of greater than 0.05.

[0083] Aspect 2. The coating composition of aspect 1 , wherein the film-forming binder comprises a compound comprising carboxylate functional group, an amine functional group, an epoxide functional group, a hydroxyl functional group, a thiol functional group, a carbamate functional group, an amide functional group, a urea functional group, a (meth) acrylate functional group, a styrene functional group, a vinyl functional group, an allyl functional group, an aldehyde functional group, an acetoacetate functional group, a hydrazide functional group, a cyclic carbonate functional group, a maleic functional group, and / or an anhydride functional group.

[0084] Aspect 3. The coating composition of aspect 1 or aspect 2, wherein the filmforming binder further comprises a curing agent.

[0085] Aspect 4. The coating composition of aspect 3, wherein the curing agent comprises an aminoplast, a phenoplast, a polyisocyanate, a blocked isocyanate, a polyepoxide, a beta-hydroxylaklylamide, a polyacid, an organometallic acid functional material, a polyamine, a polyamide, a polysulfide, a polythiol, a polyene such as a poly (meth) acrylate, a polyol, and / or a poly silane.

[0086] Aspect 5. The coating composition of any of the preceding aspects, comprising the film-forming binder in an amount of at least 20% by weight based on total solids weight of the coating composition, such as at least 30% by weight.

[0087] Aspect 6. The coating composition of any of the preceding aspects, comprising the film-forming binder in an amount of no more than 90% % by weight based on total solids weight of the coating composition, such as no more than 80% by weight.

[0088] Aspect 7. The coating composition of any of the preceding aspects, comprising the film-forming binder in an amount of 20% by weight to 90% by weight based on total solids weight of the coating composition, such as 30% by weight to 80% by weight.

[0089] Aspect 8. The coating composition of any of the preceding aspects, wherein the magnesium oxide comprises a nano-sized magnesium oxide and / or a micron-sized magnesium oxide.

[0090] Aspect 9. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a number average particle size of at least 0.5 micron measured using transmission electron microscopy, such as at least 1 micron.

[0091] Aspect 10. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a number average particle size of no more than 50 microns measured using transmission electron microscopy, such as no more than 30 microns.

[0092] Aspect 11. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a number average particle size of 0.5 micron to 50 microns measured using transmission electron microscopy, such as 1 micron to 30 microns.

[0093] Aspect 12. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a number average particle size of at least 10 nm measured using transmission electron microscopy.

[0094] Aspect 13. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a number average particle size of no more than 499 nm measured using transmission electron microscopy, such as no more than 100 nm.

[0095] Aspect 14. The coating composition of any of the preceding aspect, wherein the magnesium oxide has a number average particle size of 10 nm to 499 nm measured using transmission electron microscopy, such as 10 nm to 100 nm.

[0096] Aspect 15. The coating composition of any of the preceding aspects, wherein the magnesium oxide comprises ultrafine particles.

[0097] Aspect 16. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a B.E.T. specific surface area of at least 10 m2 / g as determined by nitrogen adsorption according to ASTM D3663-78.

[0098] Aspect 17. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a B.E.T. specific surface area of 30 m2 / g to 500 m2 / g as determined by nitrogen adsorption according to ASTM D3663-78, such as 80 m2 / g to 250 m2 / g.

[0099] Aspect 18. The coating composition of any of the preceding aspects, wherein the magnesium oxide has a spherical morphology, a cubic morphology, a platy morphology, a polyhedric morphology, and / or an acicular morphology.

[0100] Aspect 19. The coating composition of any of the preceding aspects, comprising the magnesium oxide in an amount of at least 6% by weight based on total solids weight of the coating composition, such as at least 20% by weight.

[0101] Aspect 20. The coating composition of any of the preceding aspects, comprising the magnesium oxide in an amount of no more than 60% by weight based on total solids weight of the coating composition, such as no more than 50% by weight.

[0102] Aspect 21. The coating composition of any of the preceding aspects, comprising the magnesium oxide in an amount of 6% by weight to 60% by weight based on total solids weight of the coating composition, such as 20% by weight to 50% by weight.

[0103] Aspect 22. The coating composition of any of the preceding aspects, wherein the lithium compound comprises a lithium oxide, lithium dihydrogen phosphate, lithium oxalate, and / or a lithium salt such as lithium hydroxide, lithium sulfate, lithium citrate, lithium acetate, lithium tartrate, and / or lithium nitrate.

[0104] Aspect 23. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of at least 1, such as at least 5.

[0105] Aspect 24. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of at least 10, such as at least 20.

[0106] Aspect 25. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of no more than 1,000, such as no more than 500.

[0107] Aspect 26. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of 0.05 to 1,000, such as 1 to 1,000.

[0108] Aspect 27. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of 5 to 1,000, such as 10 to 1,000.

[0109] Aspect 28. The coating composition of any of the preceding aspects, wherein the lithium compound has a Ksp in water at 25°C of 20 to 500.

[0110] Aspect 29. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 20°C of greater than 3g / 100 ml, such as greater than 5 g / 100 ml.

[0111] Aspect 30. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 20°C of greater than 8g / 100 ml, such as greater than 10 g / 100 ml.

[0112] Aspect 31. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 20°C of greater than 12g / 100 ml.

[0113] Aspect 32. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 30°C of greater than 3g / 100 ml, such as greater than 5 g / 100 ml.

[0114] Aspect 33. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 30°C of greater than 8g / 100 ml, such as greater than 10 g / 100 ml.

[0115] Aspect 34. The coating composition of any of the preceding aspects, wherein the lithium compound has a water solubility at 30°C of greater than 12g / 100 ml.

[0116] Aspect 35. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of at least 0.01% by weight based on total solids weight of the composition, such as at least 0.05% by weight.

[0117] Aspect 36. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of less than 1% by weight based on total solids weight of the composition, such as no more than 0.5% by weight.

[0118] Aspect 37. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of 0.01% by weight to less than 1% by weight based on total solids weight of the composition, such as 0.05% by weight to 0.5% by weight.

[0119] Aspect 38. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of at least 0.01% by volume based on total solids volume of the composition, such as at least 0.05% by volume.

[0120] Aspect 39. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of less than 1% by volume based on total solids volume of the composition, such as no more than 0.5% by volume.

[0121] Aspect 40. The coating composition of any of the preceding aspects, comprising the lithium compound in an amount of 0.01% by volume to less than 1% by volume based on total solids volume of the composition, such as 0.05% by volume to 0.5% by volume.

[0122] Aspect 41. The coating composition of any of the preceding aspects, further comprising a corrosion inhibitor in addition to the magnesium oxide and the lithium compound.

[0123] Aspect 42. The coating composition of aspect 41, comprising the additional corrosion inhibitor in an amount of at least 0.05% by weight based on total solids weight of the coating composition, such as at least 0.1% by weight.

[0124] Aspect 43. The coating composition of aspect 41 or aspect 42, comprising the additional corrosion inhibitor in an amount of no more than 5% by weight based on total solids weight of the coating composition, such as no more than 4% by weight.

[0125] Aspect 44. The coating composition of any of aspects 41 to 43, comprising the additional corrosion inhibitor in an amount of 0.05% by weight to 5% by weight based on total solids weight of the coating composition, such as 0.1% by weight to 4% by weight.

[0126] Aspect 45. The coating composition of any of aspects 1 to 40, wherein the coating composition is substantially free, or essentially free, or completely free, of a corrosion inhibitor in addition to the magnesium oxide and the lithium compound.

[0127] Aspect 46. The coating composition of the preceding aspects, wherein the coating composition is substantially free, or essentially free, or completely free, of molybdenum, hexavalent chromium, and / or a zinc salt of 2, 5 -dimercapto- 1, 3, 4-thiadiazole.

[0128] Aspect 47. The coating composition of any of the preceding aspects, wherein the coating composition is formulated as a liquid solvent-based coating composition.

[0129] Aspect 48. The coating composition of any of aspects 1 to 46, wherein the coating composition is formulated as a liquid water-based coating composition.

[0130] Aspect 49. The coating composition of any of aspects 1 to 46, wherein the coating composition is formulated as a powder coating composition, a thermoset composition, a thermoplastic composition, a IK composition, and / or a multi-component composition such as a 2K composition.

[0131] Aspect 50. A method for coating a substrate comprising: applying the coating composition of any of the preceding aspects to a surface of the substrate to form a coating.

[0132] Aspect 51. The method of aspect 50, further comprising applying a second coating composition to the first coating to form a second coating.

[0133] Aspect 52. A substrate comprising a coating a surface thereof, formed from the coating composition of any of aspects 1 to 49.

[0134] Aspect 53. The substrate of aspect 52, wherein the coating has a dry film thickness of 0.5 mil to 10 mil.

[0135] Aspect 54. The substrate of aspect 52 or aspect 53, comprising a second coating formed on the first coating.

[0136] Aspect 55. The substrate of aspect 54, wherein the second coating comprises a silicone modified polyester coating, a fluoropolymer coating, and / or a polyurethane coating.

[0137] Aspect 56. The substrate of any of aspects 52 to 55, comprising a metal such as aluminum and / or steel, and / or a metal alloy, such as an aluminum alloy comprising copper.

[0138] Aspect 57. The substrate of any of aspects 52 to 56, in the form of a metal sheet, coil, aircraft part, and / or a three-dimensional component formed by an additive manufacturing process.

[0139] Aspect 58. The substrate of any of aspects 52 to 57, wherein there is no intermediate layer between the substrate and the coating, or the substrate comprises one or more intermediate layers between the substrate and the coating, such as an aluminum cladding layer, an anodized oxide layer, a conversion coating, such as a chromate conversion coating, a nonchromate treatment, and / or a pretreatment.

[0140] Aspect 59. The substrate of any of aspects 52 to 58, wherein the substrate comprises an aircraft, a vehicle, a personal electronic device, a part, an article, and / or components thereof.

[0141] Aspect 60. A use of the composition of any of aspects 1 to 49 to form a coating that exhibits no pitting from dis-bonded corrosion pitting testing.

[0142] Aspect 61 . The use of aspect 60 to form a coating that exhibits a pencil hardness rating after SKYDROL immersion of 4H.

[0143] Aspect 62. The use of aspect 60 or aspect 61 to form a coating that exhibits a dry adhesion rating of 5B.

[0144] Aspect 63. The use of any of aspects 60 to 62 to form a coating that exhibits a wet adhesion rating of 5B.

[0145] Aspect 64. The use of any of aspects 60 to 63 to form a coating that exhibits a scribe shine rating of at least 30, such as at least 70 tested according to ASTM B117-19 on bare 2024-T3 aluminum panels after 1000 hours of salt spray.

[0146] Aspect 65. The use of any of aspects 60 to 64 to form a coating that exhibits 10 or fewer scribe blisters, such as 5 or fewer scribe blisters tested according to ASTM B117-19 on bare 2024-T3 aluminum panels after 1000 hours of salt spray.

[0147] Aspect 66. The use of any of aspects 60 to 65 to form a coating that exhibits a maximum scribe blister size of 6.0 mm or less, such as 3.0 mm or less tested according to ASTM Bl 17- 19 on bare 2024-T3 aluminum panels after 1000 hours of salt spray.

[0148] Aspect 67. The use of any of aspects 60 to 66 to form a coating that exhibits a scribe shine rating of 0 tested according to ASTM Bl 17-19 on bare 2024-T3 aluminum panels after 1000 hours of salt spray.Examples

[0149] The following examples are intended to illustrate the disclosure and should not be construed as limiting the disclosure in any way.Preparation of Coating Compositions

[0150] Coating compositions, Control and Examples 1-4, were prepared using the magnesium oxide (MgO) and lithium salt raw materials as shown in Table 1.Table 1 : Raw Materials and Suppliers

[0151] Epoxy-amine 2K (two-package) coating compositions, Control and Examples 1-4, were prepared using the components and weights as shown in Table 2.Table 2: Coating compositions for Control and Examples 1-4

[0152] For each Part 1, all components were weighed and placed into glass jars.Dispersing media was then added to each jar in amounts of approximately 35% of the total weight of each Part 1. The jars were sealed with lids and placed on a Lau DAS 200 Dispersing Unit (Lau GmbH) with a dispersion time of 3 hours. All final dispersions had Hegman gauge readings greater than 7. The Part 2 was similarly prepared. Prior to coating application, the corresponding amounts of Pail 1 and Pail 2 as shown for each coating composition in Table 2 were combined, mixed thoroughly, and given an induction time between 10 and 15 minutes.

[0153] Summaries of the weight percent of components of the compositions based on total solids weight of Control and Examples 1-4 arc shown in Table 3. Summaries of the volume percent of components of the compositions based on total solids by volume of Control and Examples 1-4 are shown in Table 4.Table 3: Summary of the percent MgO and lithium salt on total solids by weightTable 4: Summary of the percent MgO and lithium salt on total solids by volumePreparation of Coated Materials and Testing Methods

[0154] Dis-bonded Corrosion Test Sample Preparation and Testing Method: The disbonded corrosion test is intended to simulate corrosion from water, or salt water, trapped in a blister under a coating that has dis-bonded from the metal substrate.

[0155] Control and Example 1-4 coating compositions were spray applied to 0.6-1.2 mils on 6 cm x 10 cm polycarbonate sheet and allowed to cure at room temperature for 14 days. Each coated sheet was then assembled with a 7.6cm x 15.2cm uncoated clad 2024-T3 aluminum panelwith the coated side of the polycarbonate sheet facing the uncoated clad aluminum panel. The assembly was scaled on three sides with a commercial sealant (PR-1776, available form PPG Aerospace, CA, US, and cured according to manufacturer’s specifications). The assembly resulted in an open envelope with a gap at the top. The assembly gap was filled with 0.5 % percent by weight sodium chloride (NaCl) solution. The samples were held at 50°C for 7 days and refilled with deionized water every day. Pitting corrosion on the clad aluminum surface was visually checked after seven days of testing and rated as severe, moderate, light, or no pitting, according to the parameters set forth in Table 5.Table 5

[0156] Coated Metal Panel Preparation: Bare and clad 2024-T3 aluminum panels were cleaned using an acetone wipe followed by wet abrading using a SCOTCH-BRITE 7447 pad to produce a water-break free surface. As used herein, water-break free surface refers to a surface that maintains a continuous water film for a period of at least 30 seconds after having been rinsed with clean water at room temperature. Panels were rinsed thoroughly with water and allowed to dry. A final wipe with methyl ethyl ketone was performed prior to coating application.

[0157] The coating compositions, Control and Examples 1-4, were spray applied onto 2024-T3 aluminum alloy substrate panels to a dry film thickness of between 0.6 to 1.2 mils using an air atomized spray gun. After drying 2 hours at room temperature, a commercially available polyurethane coating CA8000 / B70846 (PPG Aerospace, California) was applied on top of each coated film, Control and Examples 1-4. The coating system comprising, in this case, Control, or Examples 1-4, and a polyurethane coating, was allowed to cure at room temperature for 14 days before any testing.Coated Panel Testing Procedures

[0158] Coated Metal Panel Salt Spray Corrosion Resistance: Corrosion resistance on the coated metal panels was determined according to ASTM B117-19 (Standard Practice for Operating Salt Spray (Fog) Apparatus). Test panels were prepared as described above using at least three abraded bare or clad aluminum panels of approximate 0.032-inch thickness. Twodiagonal marks (scribe lines) were machine scribed extending from corner to corner on each panel. The width of scribe lines was between 0.031 and 0.064 inch and penetrated through the coating and into the base metal. Test panels were exposed to 5 percent salt spray fog for 1000 hours or 3000 hours, with painted side up.

[0159] The panels were examined for corrosion and blisters after salt spray exposure according to the following scale:

[0160] Scribe Corrosion: Rating was 0 to 100 and number represents percent of scribe area exhibiting visible corrosion, wherein a lower rating number was better.

[0161] Shiny / Nature of Scribe: Rating was 0-100 and number represents percent of scribe which is shiny scribe, wherein a higher rating number was better.

[0162] Blisters: Total number of blisters were counted adjacent to scribe and away from scribe (that is, on the face of the panel). Blisters were counted up to 30, wherein a lower rating number was better.

[0163] Blister Size: The size of the largest blister adjacent to the scribe was measured in millimeters (mm).

[0164] Crosshatch Adhesion Testing: Crosshatch adhesion was determined according to ASTM D3359-17 (Standard Test Methods for Measuring Adhesion by Tape Test), method B. A crosshatch pattern was scribed through the coating down to the substrate. A strip of 1-inch (25.4 mm) wide masking tape (such as 3M 250 or equivalent) was applied onto the scribed coating.The tape was pressed down using two passes of a 4.5-pound rubber covered roller. The tape was then removed in one abrupt motion perpendicular to the panel. The adhesion was rated by a visual examination of the coating at the crosshatch area using the provided rating system. Dry adhesion was tested after fully curing the coating system for 14 days. Wet adhesion was tested on a fully cured coating system after immersing the test panel in water at 75°F (23°C) for 24 hours. Panels were removed from the water, wiped dry with a paper towel, and tested after 5 minutes.

[0165] Pencil Hardness: Pencil hairiness was determined in accordance with ASTM D3363-22 (Standard Test Method for Film Hardness by Pencil Test). The hairiness of each coating composition was determined relative to a standard set of pencil leads by scratching the leads across the coating at a 45-degree angle for about one-quarter of an inch. The process wasrepeated until a lead was identified that did not scratch the film. The number of the lead was recorded as the hardness.

[0166] SKYDROL Resistance: The fully cured coated panels were immersed in the hydraulic fluid SKYDROL LD-4 (available from Solutia, Inc.) at room temperature for 30 days. After 30 days immersion, the panels were removed from the fluid, wiped dry with a paper towel, and immediately tested for Pencil Hardness.Testing Results

[0167] Dis-bonded Corrosion Resistance Test Results: Dis-bonded corrosion pitting results after 7 days salt exposure are described in Table 6.Table 6: Dis-Bonded Corrosion Pitting Corrosion Results

[0168] As shown in Table 6, corrosion pitting resistance was significantly improved in all Examples with MgO particles and lithium salt as compared with the Control.

[0169] Table 7 shows the pencil hardness, dry and wet adhesion, and pencil hardness after SKYDROL immersion testing of bare 2024-T3 aluminum panels coated with Control or Examples 1, 2, or 3 and polyurethane coating. All coating systems had comparable pencil hardness, adhesion and SKYDROL resistance.Table 7: Pencil Hardness and Adhesion on Abraded Bare 2024-T3 Aluminum

[0170] Table 8 shows the corrosion performance of bare 2024-T3 aluminum panels coated with Control or Examples 1, 2, or 3 and polyurethane coating after 1000 hours of exposure.Table 8: Corrosion results after 1,000 hours of neutral salt spray on abraded bare aluminum

[0171] Table 9 shows the corrosion performance of clad 2024-T3 aluminum panels coated with Control or Examples 1, 2, or 3 and polyurethane coating after 1000 hours of exposure.Table 9: Corrosion results after 1,000 hours of neutral salt spray on abraded clad aluminum

[0172] Table 10 shows the corrosion performance of 2024-T3 bare aluminum panels coated with Control or Examples 1, or 4 and polyurethane coating after 3000 hours of exposure.Table 10: Corrosion results on abraded bare aluminum after 3,000 hours of neutral salt spray

[0173] Table 11 shows the corrosion performance of 2024-T3 bare aluminum panels coated with Control or Examples 1, or 4 and polyurethane coating after 3000 hours of exposure.Table 11 : Corrosion results on abraded clad aluminum after 3,000 hours of neutral salt spray

[0174] The corrosion resistance results shown in Tables 8-11 demonstrate that metal panels coated with the coating compositions of the present disclosure comprising a film-forming binder, magnesium oxide particles, and a lithium salt, such as lithium hydroxide or lithium sulfate, Examples 1-4, provided improved corrosion resistance as compared with the Control.

[0175] Whereas particular features of the present disclosure have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the coating composition, coating, and methods disclosed herein may be made without departing from the scope in the appended claims.

Claims

We claim:

1. A coating composition comprising:(a) a film-forming binder;(b) magnesium oxide; and(c) a lithium compound in an amount of 0.01% by weight to less than 1% by weight based on total solids weight, wherein the lithium compound has a solubility constant (Ksp) in water at 25 °C of greater than 0.05.

2. The coating composition of claim 1, wherein the film-forming binder comprises an organic resin.

3. The coating composition of claim 2, wherein the film-forming binder further comprises a curing agent.

4. The coating composition of claim 3, wherein:(a) the organic resin comprises an epoxide functional group; and / or(b) the curing agent comprises an amine functional group.

5. The coating composition of any of the preceding claims, wherein the coating composition comprises the film-forming binder in an amount of 20% by weight to 90% by weight based on total solids weight of the coating composition.

6. The coating composition of any of the preceding claims, wherein the coating composition comprises the magnesium oxide in an amount of 6% by weight to 60% by weight based on total solids weight of the coating composition.

7. The coating composition of any of the preceding claims, wherein the lithium compound comprises a lithium salt.

8. The coating composition of claim 7, wherein the lithium salt comprises lithium sulfate and / or lithium hydroxide.

9. The coating composition of any of the preceding claims, wherein the coating composition is substantially free of molybdenum.

10. The coating composition of any of the preceding claims, further comprising a third coiTosion inhibitor in addition to the magnesium oxide and the lithium compound.

11. The coating composition of claim 10, wherein the coating composition comprises the third coiTosion inhibitor in an amount of 0.01% by weight to 5% by weight based on total solids weight of the composition.

12. The coating composition of any of the preceding claims, formulated as a liquid coating composition or a powder coating composition.

13. The coating composition of any of the preceding claims, wherein the coating composition is substantially free of hexavalent chromium.

14. A method for coating a substrate comprising: applying the coating composition of any of the preceding claims to a surface of the substrate to form a first coating.

15. A substrate comprising a coating on a surface thereof, formed from the coating composition of any of claims 1 to 13.

16. The substrate of claim 15, comprising a second coating formed on the first coating.

17. The substrate of claim 16, wherein the second coating comprises a silicone modified polyester coating, a fluoropolymer coating, and / or a polyurethane coating.

18. The substrate of any of claims 15 to 17, comprising a metal or metal alloy, such as aluminum or steel.

19. The substrate of claim 18, wherein the metal alloy comprises an aluminum alloy comprising copper.

20. The substrate of any of claims 15 to 19, in the form of a metal sheet, coil, or aircraft part.

Images