RU2727808C2 - Curable film-forming compositions containing lithium silicates as corrosion inhibitors, and multilayered metal substrates with coating - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to a curable film-forming composition containing: (1) a curable organic film-forming binding component and (2) a corrosion inhibiting component containing lithium silicate present in the curable film-forming composition in amount of 0.1–4.5 wt. % of lithium. Invention also relates to coated metal substrates comprising multilayer metal substrates with a coating containing said composition, as well as to a multilayered metal substrate with a coating comprising: (a) a metal substrate; (b) a first curable film-forming composition supported on said metal substrate; and (c) a second curable film-forming composition applied on at least a portion of the first curable film-forming composition. First and second cured film-forming compositions independently comprise: (1) a curable, organic film-forming binder; and (2) a corrosion inhibiting component containing lithium silicate, magnesium oxide and/or azole.EFFECT: disclosed are curing film-forming compositions containing lithium silicates as corrosion inhibitors, and multilayered metal substrates with coating.22 cl, 21 tbl

Description

The technical field to which the invention relates

The present invention relates to curable film-forming compositions that contain lithium silicate. In addition, the present invention relates to substrates at least partially coated with a coating deposited from such a composition and to multilayer composite coatings in which at least two layers of coating are deposited from a coating composition containing a corrosion inhibiting component.

State of the art

Coatings are applied to devices, automobiles, aircraft, and the like for a variety of reasons, mainly for aesthetic reasons, corrosion protection, and / or to improve performance such as durability and protection from physical damage. In order to increase the corrosion resistance of a metal substrate, corrosion inhibitors are commonly used in coatings applied to the substrate. However, government regulations related to health and the environment have led to the phasing out of certain corrosion inhibitors and other additives in coating compositions, which has spurred the production of effective coating compositions.

It would be desirable to develop curable film-forming compositions that exhibit improved corrosion resistance using alternative corrosion inhibitors.

Summary of the invention

The present invention relates to a curable film-forming or coating composition comprising:

(1) a curable, organic film-forming binder component; and

(2) a corrosion inhibiting component containing lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5 wt% lithium, based on the total weight of solid resins in the curable film-forming composition.

In addition, there is provided a metal substrate at least partially coated with the curable film-forming composition described above.

Also provided is a coated multilayer metal substrate that comprises:

(a) a metal substrate;

(b) the above-described curable film-forming composition applied to said metal substrate; and

(c) an additional layer of coating applied over at least a portion of the curable film-forming composition.

In addition, a multilayer coated metal substrate has been developed containing:

(a) a metal substrate;

(b) a first curable film-forming composition applied to said metal substrate, the first curable film-forming composition comprising:

(1) a curable, organic film-forming binder component; and

(2) a component that inhibits corrosion; and

(c) a second curable film-forming composition applied over at least a portion of the first curable film-forming composition. The second curable film-forming composition contains:

(1) a curable, organic film-forming binder component that is the same as or different from the curable, organic film-forming binder component in the first curable film-forming composition; and

(2) a corrosion inhibiting component that is the same as or different from the curable, organic film-forming binder component in the first curable film-forming composition; and where the corrosion inhibiting component (2) in each of the first and second curable film-forming composition independently comprises: (i) a lithium compound containing lithium silicate and / or a lithium salt; (ii) magnesium oxide; and / or (iii) an azole.

Detailed description of the invention

Except for the working examples, or unless otherwise specified, all numerical values, quantities, quantities and percentages, such as denoting the amount of materials, reaction time and temperature, quantitative ratios, values for molecular weight (or number average molecular weight ("M _n " ), or weighted average molecular weight (“M _w ”)), and others in the rest of the description can be considered as if they were preceded by the word “approximately”, even if the expression “about” may definitely be absent in meaning, quantity or range. Therefore, unless otherwise indicated, the numerical parameters set forth in the following description and the appended claims are approximate and may vary depending on the desired characteristics that can be obtained in the present invention. At the very least, and not as an attempt to limit the invention to the doctrine of equivalents for the claims, each numerical parameter should be considered at least in light of the number of significant digits shown and using standard rounding techniques.

While the numerical values and parameters that define the broad scope of the invention are approximate, the numerical values given in the specific examples are indicated as precisely as possible. However, any numerical value will inevitably contain some errors, necessarily due to the standard variation encountered in the respective test measurements. In addition, when various ranges of numerical values are given in the invention, it is intended that any combination of the recited values may be used, including the recited values.

Plural references that are used in the invention also include the singular and vice versa. For example, while the invention is described with the term lithium silicate, the plural term may be used to include a mixture of such silicates.

Any numerical references to amounts, unless otherwise indicated, are by weight. The term "equivalent weight" is a calculated value based on the relative amounts of the various components used in the preparation of a particular material, based on the solid of a particular material. Relative amounts are those amounts that result from the theoretical weight in grams of a material similar to a polymer made from the components and give the theoretical number of specific functional groups that are present in the resulting polymer. In order to obtain the equivalent weight, the theoretical polymer weight is divided by the theoretical number of functional group equivalents. For example, the equivalent weight of urethane is based on the equivalents of the urethane groups in the polyurethane material.

Used in the invention, the term "polymer" is intended to refer to prepolymers, oligomers, and both homopolymers and copolymers; the prefix "poly" means two or more.

In addition, molecular weights, either number average (M _n ) or weighted average (M _w ), are determined by gel permeation chromatography using polystyrene as a standard, as is well known to those skilled in the art and is, for example, discussed in the patent US No. 4,739,019, at column 4, lines 2-45.

As used herein, the terms “based on the total weight of solid resins” or “based on the total weight of organic solid binders” (used interchangeably) of the composition mean that the amount of component added during the formation of the composition is based on the total weight of solid resins (non-volatile ) film-forming materials, including cross-linking agents and polymers present during the formation of the composition, but not including water and other solvents, or any solid additives such as blocked amine stabilizers, photoinitiators, pigments including filling pigments and fillers, flow additives, catalysts and UV absorbers.

As used herein, the terms “thermosetting” and “curable” can be used interchangeably and refer to resins that irreversibly “harden” upon curing or crosslinking when the polymer chains of the polymer components are covalently linked together. This characteristic is usually associated with the process of crosslinking the components of the composition, which is often initiated, for example, thermally or by radiation. See Hawley, Gessner G., The Condensed Chemical Dictionary, 9th edition, p. 856; Surface Coatings, Volume 2, Oil and Color Chemists' Association, Australia, TAFE Educational Books (1974). Curing or crosslinking processes can also be carried out under ambient conditions. The expression "environmental conditions" means that the coating is involved in a thermosetting reaction without exposure to heat or other energy, for example, without firing in an oven, using compressed air, or the like. Typically the ambient temperature ranges from 60 to 90 ° F (15.6 to 32.2 ° C), for example, a typical room temperature is 72 ° F (22.2 ° C). When cured or cross-linked, thermosetting resin cannot melt under heat and does not dissolve in solvents.

The curable film-forming compositions of the present invention can be prepared in a solvent or in water. Curable compositions contain:

(1) a curable organic film-forming binder. In turn, the organic film-forming binder component (1) may typically contain (a) a resin component that includes reactive functional groups; and (b) a curing agent component comprising functional groups that interact with functional groups in resin component (a), although the film-forming binder component itself may also crosslink with itself rather than with an additional curing agent (ie, self-crosslinking).

The resin component (a) used in the organic film-forming binder component (1) of the curable film-forming compositions of the present invention may be selected from one or more acrylic polymers, polyesters, polyurethanes, polyamides, polyethers, polythioethers, polythioethers, polythioethers, polythiols, polyenes, polyols, polysilanes, polysiloxanes, fluoropolymers, polycarbonates and epoxy resins. Typically, these compounds, which are not necessarily polymers, can be prepared by any method known to those skilled in the art. The functional groups in the film-forming binder can be selected from at least one of: carboxylic acid groups, amine groups, epoxy groups, hydroxyl groups, thiol groups, carbamate groups, amide groups, urea groups, (meth) acrylate groups, styrene groups, vinyl groups, allyl groups, aldehyde groups, acetoacetate groups, hydrazide groups, cyclic carbonate, acrylate, maleic and mercaptan groups. The functional groups in the film-forming binder are chosen so that they can interact with functional groups of the curing agent (b) or can self-crosslink.

Suitable acrylic compounds include copolymers of one or more alkyl esters of acrylic acid or methacrylic acid, optionally together with one or more other polymerizable ethylenically unsaturated monomers. Useful alkyl esters of acrylic acid or methacrylic acid include aliphatic alkyl esters containing from 1 to 30, and often from 4 to 18, carbon atoms in the alkyl group. Non-limiting examples include methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Suitable other copolymerizable ethylenically unsaturated monomers include vinyl aromatics such as styrene and vinyl toluene; nitriles such as acrylonitrile and methacrylonitrile; vinyl and vinylidene halides such as vinyl chloride and vinylidene fluoride; and vinyl esters such as vinyl acetate.

Acrylic copolymers can include hydroxyl functional groups, which are often found in the polymer, by including one or more hydroxyl functional monomers in the reactants used to make the copolymer. Useful hydroxyl functional monomers include hydroxyalkyl acrylates and methacrylates, typically having 2 to 4 carbon atoms in the hydroxyalkyl group, such as hydroxyethyl acrylate, hydroxypropyl acrylate,

4-hydroxybutyl acrylate, hydroxy-functional adducts of caprolactone and hydroxyalkyl acrylates, and the corresponding methacrylates, as well as the beta-hydroxyether functional monomers described below. In addition, acrylic polymers can be prepared from n- (alkoxymethyl) acrylamides and n- (alkoxymethyl) methacrylamides.

Beta-hydroxyether functional monomers can be prepared from ethylenically unsaturated, epoxy functional monomers and carboxylic acids having from about 13 to about 20 carbon atoms, or from ethylenically unsaturated acidic functional monomers and epoxy compounds containing at least 5 carbon atoms that are not can polymerize with ethylenically unsaturated acid functional monomers.

Useful ethylenically unsaturated, epoxy functional monomers that are used to prepare beta hydroxy ester functional monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, metal glycidyl ether, 1: 1 (molar) adducts of ethylenically unsaturated monohydroxy epoxy monomers, glycidyl aminocyanate mono esters of polymerizable polycarboxylic acids such as maleic acid. (Note: These epoxy-functional monomers can also be used to prepare epoxy-functional acrylic polymers.) Examples of carboxylic acids include saturated monocarboxylic acids such as isostearic acid and aromatic unsaturated carboxylic acids.

Useful ethylenically unsaturated acid functional monomers used to prepare beta-hydroxy ester functional monomers include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid; dicarboxylic acids such as itaconic acid, maleic acid and fumaric acid; and monoesters of dicarboxylic acids such as monobutyl maleate and monobutyl itaconate. Typically, ethylenically unsaturated acid functional monomers and epoxy compounds are reacted in an equivalent ratio of 1: 1. Epoxy compounds do not contain an ethylenically unsaturated group that would participate in free radical initiated polymerization with an acidic unsaturated monomer functionality. Useful epoxy compounds include 1,2-pentene oxide, styrene oxide, and glycidyl esters or ethers, often containing 8 to 30 carbon atoms, such as butyl glycidyl ether, octyl glycidyl ether, phenyl glycidyl ether, and para- (tertiary butyl) phenyl glycidyl ether. Specific glycidyl esters include esters with the structure:

where R is a hydrocarbon radical containing from about 4 to about 26 carbon atoms. Typically, R is a branched hydrocarbon group having from about 8 to 10 carbon atoms, such as neopentanoate, neoheptanoate, or neodecanoate. Suitable carboxylic acid glycidyl esters include VERSATIC ACID 911 and CARDURA E, which are commercially available from Shell Chemical Co.

Carbamate functional groups can be incorporated into an acrylic polymer by copolymerizing acrylic monomers with a carbamate functional vinyl monomer such as a carbamate functional alkyl ester of methacrylic acid, or by reacting a hydroxyl functional acrylic polymer with a low molecular weight carbamate functional material such as can be derived from an alcohol or simple glycol ether, by the reaction of transcarbamoylation. In this reaction, a low molecular weight carbamate functional material derived from an alcohol or a glycol ether reacts with the hydroxyl groups of an acrylic polyol to form a carbamate functional acrylic polymer and a starting alcohol or glycol ether. A low molecular weight carbamate functional material derived from an alcohol or a glycol ether can be prepared by reacting an alcohol or a glycol ether with urea in the presence of a catalyst. Suitable alcohols include low molecular weight aliphatic, cycloaliphatic and aromatic alcohols such as methanol, ethanol, propanol, butanol, cyclohexanol, 2-ethylhexanol, and 3-methylbutanol. Suitable glycol ethers include ethylene glycol methyl ether and propylene glycol methyl ether. The most commonly used are propylene glycol methyl ether and methanol. In addition, other carbamate functional monomers that are known to those skilled in the art can be used.

The amide functional group can be incorporated into the acrylic polymer using suitable functional monomers in the preparation of the polymer, or by converting other functional groups to amide groups using techniques known to those skilled in the art. Likewise, other functional groups can be included if desired, using suitable functional monomers, if available, or conversion reactions, if necessary.

Acrylic polymers can be prepared by an aqueous emulsion polymerization technique and used directly in the preparation of aqueous coating compositions, or can be prepared by an organic solution polymerization technique for compositions formed in a solvent. When prepared by polymerization in organic solution, with groups capable of forming salts, such as acid or amine groups, by neutralizing these groups with a base or acid, these polymers can be dispersed in an aqueous medium. In general, any method for preparing said polymers known to those skilled in the art using conventional amounts of monomers can be used.

In addition to acrylic polymers, the resin component (a) in the film-forming binder component (1) of the curable film-forming composition may be an alkyd resin or a polyester. Such polymers can be obtained by a known method by condensation of polyhydric alcohols and polycarboxylic acids. Suitable polyhydric alcohols include, but are not limited to, ethylene glycol, propylene glycol, butylene glycol, 1,6-hexylene glycol, neopentylene glycol, diethylene glycol, glycerol, trimethylolpropane, and pentaerythritol. Suitable polycarboxylic acids include, but are not limited to, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and trimellic acid. In addition to the aforementioned polycarboxylic acids, acid functional equivalents such as anhydrides, if any, or lower alkyl esters of acids such as methyl esters can be used. When air-drying alkyd resins are desired, suitable drying oils of fatty acids can be used, which include, for example, oils derived from linseed oil, soybean oil, tall oil, anhydrous castor oil, or tung oil.

Likewise, polyamides can be made using polyacids and polyamines. Suitable polyacids include the above acids, and the polyamines can be selected from at least one of ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2-methyl -1,5-pentanediamine, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and / or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1, 12-diaminododecane, 1,3- and / or 1,4-cyclohexanediamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexanea, 2,4- and / or 2,6-hexahydrotoluylenediamine, 2,4 ' - and / or 4,4'-diaminodicyclohexylmethane and 3,3'-dialkyl-4,4'-diaminodicyclohexylmethanes (such as 3,3'-dimethyl-4,4'-diamino-dicyclohexylmethane and 3,3'-diethyl- 4,4'-diaminodicyclohexylmethane), 2,4- and / or 2,6-diaminotoluene and 2,4'- and / or 4,4'-diaminodiphenylmethane.

Carbamate functional groups can be incorporated into the polyester or polyamide by initially forming a hydroxyalkyl carbamate that can react with the polyacids and polyols / polyamines used to form the polyester or polyamide. The hydroxyalkyl carbamate condenses with an acidic functional group in the polymer to form a terminal carbamate functional group. In addition, carbamate functional groups can be incorporated into the polyester by reacting terminal hydroxyl groups in the polyester with a low molecular weight carbamate functional material in a transcarbamoylation process similar to the reaction described above in connection with the introduction of carbamate groups into acrylic polymers, or by reacting isocyanic acid with a hydroxyl functional polyester.

Other functional groups such as amine, amide, thiol, urea, or others listed above can be incorporated into the polyamide, polyester or alkyd resin, if desired, using suitable functional reagents, if available, or conversion reactions that are necessary to obtain the desired functional groups. Suitable techniques are known to those skilled in the art.

Polyurethanes can also be used as the resin component (a) in the film-forming binder component (1) of the curable film-forming composition. Among the polyurethanes that can be used are polymeric polyols, which are usually obtained by reacting polyesters of polyols or acrylic polyols such as those indicated above with a polyisocyanate such that the equivalent OH / NCO ratio is greater than 1: 1, so that hydroxyl groups were present in the product. The organic polyisocyanate used to prepare the polyurethane polyol can be an aliphatic or aromatic polyisocyanate, or a mixture thereof. Typically, diisocyanates are used, although higher polyisocyanates can be used instead of or in combination with diisocyanates. Examples of suitable aromatic diisocyanates are 4,4'-diphenylmethane diisocyanate and toluene diisocyanate. Examples of suitable aliphatic diisocyanates are unbranched aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate. In addition, cycloaliphatic diisocyanates can be used. Examples include isophorone diisocyanate and 4,4'-methylene bis (cyclohexyl isocyanate). Examples of suitable higher polyisocyanates are 1,2,4-benzene triisocyanate, polymethylene polyphenyl isocyanate, and isocyanate trimers based on 1,6-hexamethylene diisocyanate or isophorone diisocyanate. Like polyesters, polyurethanes can be prepared with unreacted carboxylic acid groups which, when neutralized with bases such as amines, provide dispersion in aqueous media.

Terminal and / or hanging carbamate functional groups can be incorporated into the polyurethane by reacting the polyisocyanate with a polymeric polyol containing terminal / hanging carbamate groups. Alternatively, carbamate functional groups can be incorporated into the polyurethane by reacting the polyisocyanate with the polyol and hydroxyalkyl carbamate or isocyanic acid as separate reactants. In addition, carbamate functional groups can be incorporated into the polyurethane by reacting a hydroxyl functional polyurethane with a low molecular weight carbamate functional material in a transcarbamoylation process similar to the reaction described above in connection with the introduction of carbamate groups into the acrylic polymer. In addition, the isocyanate functional polyurethane can react with the hydroxyalkyl carbamate to form the functional carbamate polyurethane.

Other functional groups, such as amide, thiol, urea, or others listed above, can be incorporated into the polyurethane, if desired, using suitable functional reagents, if available, or conversion reactions that are necessary to obtain the desired functional groups. These techniques are known to those skilled in the art.

Examples of polyether polyols are polyalkylene ethers of polyols, which include ethers having the following structural formulas:

(i)

or (ii)

where R ₁ is hydrogen or lower alkyl containing 1 to 5 carbon atoms and including mixed substituents, and n usually ranges from 2 to 6 and m is from 8 to 100 or higher. Also included are poly (oxytetramethylene) glycols, poly (oxytetraethylene) glycols, poly (oxy-1,2-propylene) glycols, and poly (oxy-1,2-butylene) glycols.

Also useful are polyether polyols formed by oxyalkylation of various polyols, for example, diols such as ethylene glycol, 1,6-hexanediol, Bisphenol A, and the like, or other higher polyols such as trimethylolpropane, pentaerythritol, and the like. Polyols with increased functional groups, which can be used as described above, can be obtained, for example, by oxyalkylation of compounds such as sucrose or sorbitol. One widely used oxyalkylation method is the reaction of a polyol with an alkylene oxide, for example, propylene or ethylene oxides, in the presence of an acidic or basic catalyst. Specific polyethers include those commercially available under the names TERATHANE and TERACOL, available from Invista, and POLYMEG, available from Lyondell Chemical Co.

Hanging carbamate functional groups can be incorporated into polyethers by a transcarbamoylation reaction. Other functional groups, such as acid, amine, epoxy, amide, thiol and urea, can be incorporated into polyethers, if desired, using suitable functional reagents, if available, or conversion reactions as necessary to obtain the desired functional groups. Examples of suitable amine functional polyethers include those marketed under the name JEFFAMINE, such as JEFFAMINE D2000, a polyether functional diamine available from Huntsman Corporation.

Epoxy functional polymers suitable for use as resin component (a) may include a polyepoxide chain extended by reaction with a mixture of polyepoxide and a material containing polyhydroxyl groups, selected from materials containing alcoholic hydroxyl groups and materials containing phenolic hydroxyl groups, for chain propagation or molecular weight build-up of the polyepoxide.

The extended chain polyepoxide is typically prepared by reacting a mixture of a polyepoxide and a material containing polyhydroxyl groups without solvent or in the presence of an inert organic solvent such as a ketone containing methyl isobutyl ketone and methylamine ketone, aromatic hydrocarbons such as toluene and xylene, and glycol ethers such as as diethylene glycol dimethyl ether. Typically, the reaction is carried out at a temperature of from about 80 ° C to 160 ° C for about 30 to 180 minutes, until a resinous reaction product containing epoxy groups is formed.

A typical equivalent ratio of reactants, that is, epoxy: (material containing polyhydroxyl groups), is approximately 1.00: 0.75 to 1.00: 2.00.

By definition, a polyepoxide has at least two 1,2-epoxy groups. Typically, the epoxy equivalent weight of the polyepoxide ranges from 100 to about 2000, typically from about 180 to 500. The epoxy compounds can be saturated or unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic, or heterocyclic. They may contain substituents such as halogen, hydroxyl and ethers.

Examples of polyepoxides are those which have a 1,2-epoxy equivalent of greater than one and usually about two; that is, polyepoxides, which, on average, have two epoxy groups per molecule. The most widely used polyepoxides are polyglycidyl ethers of cyclic polyols, for example, polyglycidyl ethers of polyhydric phenols such as Bisphenol A, resorcinol, hydroquinone, benzenedimethanol, phloroglucinol, and pyrocatechol; or polyglycidyl ethers of polyhydric alcohols such as alicyclic polyols, especially cycloaliphatic polyols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 2,2-bis (4-hydroxycyclohexyl) propane, 1,1-bis (4-hydroxycyclohexyl ) ethane, 2-methyl-1,1-bis (4-hydroxycyclohexyl) propane, 2,2-bis (4-hydroxy-3-tert-butylcyclohexyl) propane, 1,3-bis (hydroxymethyl) cyclohexane and 1,2 -bis (hydroxymethyl) cyclohexane. Examples of aliphatic polyols include, in particular, trimethylpentanediol and neopentyl glycol.

The materials containing polyhydroxyl groups used for chain propagation or molecular weight build-up of the polyepoxide may also be polymeric polyols such as any of the above. The present invention can include epoxy resins such as bisphenol A, bisphenol F, glycerol, novolacs, and the like diglycidyl ethers. Examples of suitable polyepoxides are described in US Pat. No. 4,681,811, at column 5, lines 33 to 58, the cited text being incorporated herein by reference.

The epoxy functional film-forming polymers can alternatively be acrylic polymers derived from epoxy functional monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and methalyl glycidyl ether. Complex polyesters, polyurethanes or polyamides derived from glycidyl alcohols or glycidylamines, or reacted with epihalohydrin, are also suitable epoxy functional resins. Epoxy functional groups can be incorporated into the resin by reacting the hydroxyl groups of the resin with epihalohydrin or dihalohydrin such as epichlorohydrin or dichlorohydrin in the presence of alkali.

Non-limiting examples of suitable fluoropolymers include alternating copolymers of fluoroethylene and alkyl vinyl ethers (such as described in US Pat. No. 4,345,057) available from Asahi Glass Company under the name LUMIFLON; fluoroaliphatic polymeric esters which are commercially available from 3M St. Paul, Minnesota under the name FLUORAD; and perfluorinated hydroxyl functional (meth) acrylate resins.

Suitable curing agents (b) for use in the film-forming binder component (1) of the curable film-forming compositions of the present invention include aminoplasts, polyisocyanates including blocked isocyanates, polyepoxides, beta-hydroxyalkylamides, polyacids, organometallic acid functional materials, polyamines, polyamines polythiols, polyenes such as polyacrylates, polyols, polysilanes, and any mixtures of the foregoing, and include those known in the art for any of these materials. The terms "curing agent", "crosslinking agent" and "crosslinker" are used interchangeably in the invention.

Useful aminoplasts can be obtained by the condensation reaction of formaldehyde with an amine or amide. Non-limiting examples of amines or amides include melamine, urea, and benzoguanamine.

Although condensates obtained from the reaction of alcohols and formaldehyde with melamine, urea, or benzoguanamine are most common, condensates with other amines or amides can be used. Formaldehyde is the most commonly used aldehyde, but other aldehydes such as acetaldehyde, crotonaldehyde, and benzaldehyde can also be used.

The aminoplast may contain imino and methylol groups. In some cases, at least a portion of the methylol groups can be esterified with alcohol to modify the cure response. For this purpose, any monofunctional alcohol can be used like methanol, ethanol, n-butyl alcohol, isobutanol, and hexanol. Non-limiting examples of suitable aminoplast resins are available from Allnex under the CYMEL® trademark and from IHEOS under the RESIMENE® trademark.

Other cross-linking agents suitable for use include polyisocyanate cross-linkers. Used in the invention, the term "polyisocyanate" is intended to include blocked (or embedded) polyisocyanates as well as unblocked polyisocyanates. The polyisocyanate can be aliphatic, aromatic, or a mixture thereof. Although higher polyisocyanates such as isocyanurates and diisocyanates are often used, diisocyanates can also be used. In addition, can be used isocyanate prepolymers, for example, polyisocyanates with polyols. Polyisocyanate crosslinking agents can be used.

Polyisocyanates can be obtained from a variety of isocyanate containing materials. Examples of suitable polyisocyanates include trimers derived from the following diisocyanates: toluene diisocyanate, 4,4'-methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, a measured mixture of 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanates, 1,6-hexamethylene diisocyanate, tetramethylxilylene diisocyanate and 4,4'-diphenylmethylene diisocyanate. In addition, blocked polyisocyanate prepolymers of various polyols such as polyesters of polyols can also be used.

If desired, isocyanate groups can be embedded or not. If the polyisocyanate is to be blocked or sealed, any suitable aliphatic, cycloaliphatic or alkylaromatic monoalcohols or phenolic compounds known to those skilled in the art can be used as the embedding agent for the polyisocyanate. Examples of suitable blocking agents include those materials that would release at elevated temperatures, such as lower aliphatic alcohols including methanol, ethanol, and n-butanol; cycloaliphatic alcohols such as cyclohexanol; alkylaromatic alcohols such as phenylcarbinol and methylphenylcarbinol; and phenolic compounds such as phenol itself and substituted phenols, the substituents not affecting coating operations such as cresol and nitrophenol. Glycol ethers can also be used as sealing agents. Suitable glycol ethers include ethylene glycol butyl ether, diethylene glycol butyl ether, ethylene glycol methyl ether, and propylene glycol methyl ether. Other suitable capping agents include oximes such as methylethylketoxime, acetone and cyclohexanone oxime, lactams such as epsilon-caprolactam, pyrazoles such as dimethylpyrazole, and amines such as dibutylamine.

Polyepoxides are suitable curing agents for polymers having carboxylic acid groups and / or amine groups. Examples of suitable polyepoxides include low molecular weight polyepoxides such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate and bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate. High molecular weight polyepoxides including the polyglycidyl ethers of the polyhydric phenols and alcohols described above are also suitable as crosslinking agents.

Beta-hydroxyalkylamides are suitable curing agents for polymers having carboxylic acid groups. Beta-hydroxyalkylamides can be described by the following structures:

where R ₁ means H or alkyl from C ₁ to C ₅ ; R ₂ is H, C ₁ to C ₅ alkyl, or:

where R ₁ is as described above; A means a bond or multivalent organic radical derived from saturated, unsaturated, or aromatic hydrocarbons, including substituted hydrocarbon radicals containing from 2 to 20 carbon atoms; m is 1 or 2; n is 0 or 2, and the sum (m + n) is at least 2, usually within the range of 2 up to and including 4. Most often, A is a C ₂ -C ₁₂ divalent alkylene radical.

Polyacids, especially polycarboxylic acids, are suitable curing agents for polymers having epoxy functional groups. Examples of suitable polycarboxylic acids include adipic, succinic, sebacic, azelaic, and dodecanedicarboxylic acids. Other suitable polyacid crosslinking agents include acrylic polymers containing acid groups derived from an ethylenically unsaturated monomer containing at least one carboxylic acid group and at least one ethylenically unsaturated monomer, i.e., free of carboxylic acid groups. These acid functional acrylic polymers can have an acid number in the range of 30 to 150. In addition, polyesters containing acid functional groups can be used. Low molecular weight polyesters and acid half-esters can be used, which are obtained by condensation of aliphatic polyols with aliphatic and / or aromatic polycarboxylic acids or anhydrides. Examples of suitable aliphatic polyols include ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, di-trimethylolpropane, neopentyl glycol, 1,4-cyclohexanedimethanol, pentaerythritol, and the like. Polycarboxylic acids and anhydrides may include, but are not limited to, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and the like. Mixtures of acids and / or anhydrides can also be used. The polyacid crosslinking agents described above are discussed in more detail in US Pat. No. 4,681,811, at column 6, line 45, to column 9, line 54, which is incorporated herein by reference.

Non-limiting examples of suitable polyamine crosslinking agents include primary or secondary diamines or polyamines in which the radicals attached to the nitrogen atoms can be saturated or unsaturated, aliphatic, alicyclic, aromatic, aliphatic with an aromatic substituent, aromatic with an aliphatic substituent and heterocyclic. Non-limiting examples of suitable aliphatic and alicyclic diamines include 1,2-ethylenediamine, 1,2-propylenediamine, 1,8-octanediamine, isophorone diamine, propane-2,2-cyclohexylamine, and the like. Non-limiting examples of suitable aromatic diamines include phenylenediamines and toluene diamines, for example, ortho-phenylenediamine and p-tolylene diamine. In addition, polynuclear aromatic diamines such as 4,4'-biphenyldiamine, methylenedianiline and monochloromethylene-dianiline are suitable.

Examples of suitable aliphatic diamines include, without limitation, ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, 1,6-diaminohexane, 2-methyl-1,5-pentanediamine, 2,5-diamino -2,5-dimethylhexane, 2,2,4- and / or 2,4,4-trimethyl-1,6-diaminohexanes, 1,11-diaminoundecane, 1,12-diaminododecane, 1,3- and / or 1 , 4-cyclohexanediamines, 1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane, 2,4- and / or 2,6-hexahydrotoluylenediamines, 2,4'- and / or 4,4'-diaminodicyclohexylmethanes and 3,3'-dialkyl-4,4'-diamino-dicyclohexylmethanes (such as 3,3'-dimethyl-4,4'-diamino-dicyclohexylmethane and 3,3'-diethyl-4,4'-diamino-dicyclohexylmethane ), 2,4- and / or 2,6-diaminotoluenes and 2,4'- and / or 4,4'-diaminodiphenylmethanes, or mixtures thereof. Cycloaliphatic diamines are commercially available from Huntsman Corporation (Houston, TX) under the designation JEFFLINK ™ such as JEFFLINK ™ 754. In addition, additional aliphatic cyclic polyamines such as DESMOPHEN NH 1520 available from Bayer Material Science and / or CLEARLINK 1000, which is a secondary aliphatic diamine available from Dorf Ketal, can be used. Also suitable is POLYCLEAR 136 (available from BASF / Hansen Group LLC), a reaction product of isophorone diamine and acrylonitrile. Other examples of suitable polyamines are described in US Pat. No. 4,046,729 at column 6, line 61 to column 7, line 26, and in US Pat. No. 3,799,854 at column 3, lines 13-50, the cited portions of which are incorporated herein by reference. In addition, additional polyamines can be used, such as ANCAVINE polyamines available from Air Products and Chemicals, Inc.

Suitable polyamides include any of those known in the art. For example, ANCAMIDE polyamides available from Air Products and Chemicals, Inc.

Suitable polyenes may include those represented by the formula:

A - (X) _m

in which A is an organic moiety, X is an olefinically unsaturated moiety and m is at least 2, typically 2 to 6. Examples of X are groups of the following structure:

(meth) acrylic (meth) allyl

where each R is a radical selected from H and methyl.

Polyenes can be compounds or polymers having olefinic double bonds in the molecule that are polymerized by radiation. Examples of such materials are (meth) acrylic copolymers with (meth) acrylic functionality, (meth) acrylates of epoxy resins, polyesters of (meth) acrylates, polyethers of (meth) acrylates, polyurethane (meth) acrylates, amino (meth) acrylates, silicone (meth) acrylates; and melamine (meth) acrylates. The number average molar mass (Mn) of these compounds is often about 200 to 10,000. The molecule often contains an average of 2 to 20 olefinic double bonds that are polymerized by radiation. In each case, aliphatic and / or cycloaliphatic (meth) acrylates are often used. (Cyclo) aliphatic polyurethane (meth) acrylates and (cyclo) aliphatic polyester (meth) acrylates are particularly suitable. Binders can be used alone or in mixture.

Specific examples of polyurethane (meth) acrylates are the reaction products of polyisocyanates such as 1,6-hexamethylene diisocyanate and / or isophorone diisocyanate, including their isocyanurate and biuret derivatives, with hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylates and / or hydroxyethyl (meth) acrylates and / or (meth) acrylates. The polyisocyanate can be reacted with hydroxyalkyl (meth) acrylate in an equivalent ratio of 1: 1 or can be reacted in an equivalent ratio of NCO / OH greater than one to produce a reaction product containing NCO groups, which can then chain with a polyol such as a diol or a triol, for example 1,4-butanediol, 1,6-hexanediol and / or trimethylolpropane. Examples of polyester (meth) acrylates are the reaction products of (meth) acrylic acid or anhydride with polyols such as diols, triols and tetrols, including alkylated polyols such as propoxylated diols and triols. Examples of polyols include 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, pentaerythritol, and propoxylated 1,6-hexanediol. Specific examples of the polyester (meth) acrylate are glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and pentaerythritol tetra (meth) acrylate.

Besides (meth) acrylates, (meth) allyl compounds or polymers can be used either alone or in combination with (meth) acrylates. Examples of (meth) allyl materials are polyallyl ethers such as 1,4-butanediol diallyl ether and trimethylolpropane triallyl ether. Examples of other (meth) allyl materials are polyurethanes containing (meth) allyl groups. For example, reaction products of polyisocyanates such as 1,6-hexamethylene diisocyanate and / or isophorone diisocyanate, including isocyanurate and their biuret derivatives, with allyl ethers having hydroxyl functional groups, such as 1,4-butanediol monoallyl ether and trimethylolpropane diallyl ether. The polyisocyanate can be reacted with an allyl ether having hydroxyl functional groups in an equivalent ratio of 1: 1, or can be reacted in an equivalent ratio of NCO / OH greater than one to produce a reaction product containing NCO groups, which can then chain with the polyol such as a diol or triol, for example 1,4-butanediol, 1,6-hexanediol and / or trimethylolpropane.

Used in the invention, the term "polythiol functional material" refers to polyfunctional materials containing two or more thiol functional groups (SH). Suitable polythiol functional materials for use in the formation of curable film-forming compositions are numerous and can vary widely. These polythiol functional materials may include those known in the art. Non-limiting examples of suitable polythiol functional materials can include polythiols having at least two thiol groups, including compounds and polymers. These polythiols can have ether linkages (-O-), sulfide linkages (-S-), including polysulfide linkages (-S _x -), in which x is at least 2, such as 2 to 4, and combinations specified bundles.

Polythiols used in the present invention include materials of the formula:

R ¹ - (SH) _n

where R ¹ is a multivalent organic moiety and n is an integer of at least 2, typically 2 to 6.

Non-limiting examples of suitable polythiols include thiol-containing acid esters of the formula HS — R ² —COOH in which R ² is an organic moiety with polyhydroxy compounds of the structure R ³ - (OH) _n in which R ³ is an organic moiety and n is at least 2, typically 2 to 6. These components can be reacted under suitable conditions to form polythiols having the general structure:

R ³ - (OC-R ² -SH) _n

||

O

in which R ² , R ³ and n have the above meanings.

Examples of thiol-containing acids are thioglycolic acid (HS-CH ₂ COOH), α-mercaptopropionic acid (HS-CH (CH ₃ ) -COOH) and β-mercaptopropionic acid (HS-CH ₂ CH ₂ COOH), with polyhydroxy compounds, such as glycols, triols, tetrols, pentaols, hexaols, and mixtures thereof. Other non-limiting examples of suitable polythiols include ethylene glycol bis (thioglycollate), ethylene glycol bis (β-mercaptopropionate), trimethylolpropane tris (thioglycollate), trimethylolpropane tris (β-mercaptopropionate), tetrakis (thioglycollate) pentaerythiopropane tetrakis (thioglycollate) pentaerythiopropionate and their mixtures.

Suitable polyacids and polyols useful as curing agents include any of those known in the art, such as those described in the invention for the preparation of polyesters.

Suitable mixtures of crosslinking agents can also be used in the invention. The amount of crosslinking agent in the curable film-forming composition typically ranges from 5 to 75 percent by weight based on the total weight of solid resins in the curable film-forming composition. For example, the minimum amount of crosslinking agent can be at least 5 percent by weight, often at least 10 percent by weight, and more often at least 15 percent by weight. The maximum amount of crosslinking agent can be 75 percent by weight, more often 60 percent by weight, or 50 percent by weight. Ranges of crosslinking agent content may include, for example, 5 to 50 percent by weight, 5 to 60 percent by weight, 10 to 50 percent by weight, 10 to 60 percent by weight, 10 to 75 percent by weight, from 15 to 50 percent by weight, 15 to 60 percent by weight, and 15 to 75 percent by weight.

The resin component (a) may include epoxy functional groups, and the curing agent component (b) may include amine functional groups.

In addition, the composition of the present invention contains a corrosion inhibiting component (2) which contains lithium silicate including lithium orthosilicate (Li ₄ SiO ₄ ) and / or lithium metasilicate (Li ₂ SiO ₃ ). The corrosion inhibiting component (2) may further comprise at least one of magnesium oxide (MgO) and an azole.

Any MgO with any number average particle size can be used according to the invention. The number average particle size can be determined by visual inspection of a photomicrograph of a transmission electron microscopy ("TEM") image as described below. For example, the MgO particles can have micron sizes, such as 0.5 to 50 microns, or 1 to 15 microns, with the size based on the average particle size. Alternatively, the MgO particles can be nano-sized, such as 10 to 499 nanometers, or 10 to 100 nanometers, the size being based on the number average particle size. It can be recognized that the specified particle sizes refer to the size of the MgO particles at the time of their introduction into the curable film-forming composition. Various coating methods can lead to agglomeration of the MgO particles, which can increase the average particle size, or shear, or other action that can reduce the average particle size. MgO particles are commercially available from a variety of sources.

Very fine MgO particles can be used in corrosion inhibiting component (2). As used herein, the term "very fine" refers to particles that have a BET specific surface area of at least 10 square meters per gram, such as 30 to 500 square meters per gram, or in some cases 80 to 250 square meters meters per gram. The term "BET specific surface area" as used herein refers to the specific surface area as determined by nitrogen adsorption according to ASTM D 3663-78, based on the Brunauer-Emmett-Teller method described in The Journal of the American Chemical Society , 60, 309 (1938).

The curable film-forming compositions of the present invention may include MgO particles having an estimated equivalent sphere diameter of no more than 200 nanometers, such as no more than 100 nanometers, or, for example, 5 to 50 nanometers. As those skilled in the art can understand, the estimated equivalent sphere diameter can be determined from the BET specific surface area using the following equation:

Diameter (nanometers) = 6000 / [BET surface area (m ² / g) * density (g / cm ³ )].

Often, MgO particles have a number average primary particle size of no more than 100 nanometers, such as no more than 50 nanometers, or no more than 25 nanometers, as determined by visual inspection of a transmission electron micrograph ("TEM") image. measuring the diameter of the particles in the image, and calculating the average primary particle size of the measured particles taking into account the magnification of the TEM image. One of ordinary skill in the art can understand how to prepare such a TEM image and determine the primary particle size based on magnification. Primary particle size refers to the smallest diameter of a sphere that will contain the entire particle. As used herein, the term "primary particle size" refers to the size of individual particles as opposed to an agglomerate of two or more individual particles.

The shape (or morphology) of the MgO particles can vary. For example, spherical morphology can usually be used, as well as particles that are cubic, planar, polyhedral, or acicular (elongated or fibrous) in shape. The particles can be completely coated with a polymer gel, contain no polymer gel at all, or partially covered with a polymer gel. Partial coating with a polymer gel means that at least some part of the particle contains a polymer gel deposited thereon, which, for example, can be covalently associated with the particle, or simply associated with the particle.

The amount of MgO used in the curable film-forming composition can vary depending on the needs of the user. For example, the curable film-forming composition may contain from 1 to 50 percent by weight of MgO particles, with a minimum, for example, 1 percent by weight, or 5 percent by weight, or 10 percent by weight, and a maximum of 50 percent by weight, or 40 percent by mass. Typical ranges include 5 to 50 percent by weight, 5 to 40 percent by weight, 10 to 50 percent by weight, and 10 to 40 percent by weight, with the percentage by weight calculated on the total weight of all solids in the curing film-forming agent. compositions including pigments.

When MgO is present in the curable film-forming composition, the corrosion inhibiting component (2) may further comprise an amino acid. Those of skill in the art can understand that amino acids are compounds that have both acidic and amine functionality, with side chains being specific for each amino acid. Amino acids can be monomeric or oligomeric, including dimers. When an oligomeric amino acid is used, the molecular weight of the oligomer, determined by gel permeation chromatography (GPC), is often less than 1000.

Particularly suitable amino acids are histidine, arginine, lysine, cysteine, cystine, tryptophan, methionine, phenylalanine and tyrosine. Mixtures can also be used. Amino acids can be L or D enantiomers, which are mirror images of each other, or mixtures thereof. Typically, L-configurations are found in proteins and nature and, as such, are widely available for purchase. Therefore, the term "amino acids" as used in the invention refers to the D- as well as L- configurations; it is assumed that only L or only D configurations can be used. Amino acids can be purchased, for example, from Sigma Aldrich, Thermo Fisher Scientific, Hawkins Pharmaceutical, or Ajinomato. Amino acids such as glycine, arginine, proline, cysteine, and / or methionine are often specifically excluded.

The amino acid can be present in any amount that enhances the corrosion resistance of the coating. For example, the amino acid can be present in an amount of 0.1 to 20 percent by weight, for example, at least 0.1 percent by weight, or at least 2 percent by weight, and at most 20 percent by weight, or at most more than 4 percent by weight; typical ranges include 0.1 to 4 percent by weight, 2 to 4 percent by weight, or 2 to 20 percent by weight, based on the total weight of solid resins in the curable film-forming composition.

In addition, an azole may be present in the corrosion inhibiting component (2), additionally or alternatively to MgO. Azoles are 5-membered heterocyclic nitrogen compounds that contain two double bonds in the heterocyclic ring, from one to three carbon atoms, and optionally a sulfur or oxygen atom. The commonly used azole is benzotriazole. Examples of other azoles are 5-methylbenzotriazole, tolyltriazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 1-phenyl-5-mercaptotetrazole, 2-amino-5-mercapto-1, 3,4-thiadiazole, 2-mercapto-1-methylimidazole, 2-amino-5-ethyl-1,3,4-thiadiazole, 2-amino-5-ethylthio-1,3,4-thiadiazole, 5-phenyltetrazole, 7H-imidazo (4,5-d) pyrimidine, and

2-aminothiazole. Also suitable are salts of any of the above compounds, such as sodium and / or zinc salts. Additional azoles include 2-hydroxybenzothiazole, benzothiazole, 1-phenyl-4-methylimidazole, and 1- (p-tolyl) -4-methylimidazole. A suitable azole-containing product is commercially available from WPC Technologies, available under the name HYBRICOR 204. In addition, mixtures of azoles can be used. Typically, the azole is present in the curable film-forming composition in an amount as low as 0.1 percent, eg, 0.1 to 25 percent by weight, based on the total weight of the solid resins in the curable film-forming composition.

Lithium silicate is present in the curable film-forming composition in an amount of 0.1 to 4.5 wt. percent lithium, for example, 0.1 to 4, 0.1 to 3.5, 0.25 to 4.5, 0.25 to 4, 0.25 to 3.5, 0.5 up to 4.5, from 0.5 to 4, or from 0.5 to 3.5, based on the total weight of solid resins in the curable film-forming composition.

In specific examples, the following combinations are contemplated: lithium silicate (orthosilicate and / or metasilicate) can be used in combination with thiazole. Lithium silicate (orthosilicate and / or metasilicate) can be used in combination with diazole. Lithium silicate (orthosilicate and / or metasilicate) can be used in combination with imidazole. Lithium silicate (orthosilicate and / or metasilicate) can be used in combination with oxazole. Lithium silicate (orthosilicate and / or metasilicate) can be used in combination with tetrazole. Lithium silicate (orthosilicate and / or metasilicate) can be used in combination with triazole. In each of the above examples, magnesium oxide can additionally be used. Alternatively, lithium silicate (orthosilicate and / or metasilicate) can be used in combination with magnesium oxide.

Often, the curing film-forming composition is substantially free of particles of lithium-aluminum alloy, clay, lithium salts, and lithium oxide (Li ₂ O). By definition, the anion, as well as the cation of the lithium salt, must dissolve in water. Therefore, lithium polysilicates such as lithium metasilicate and lithium orthosilicate used in the present invention and lithium exchange (silicate) particles are not considered lithium salts.

It is noted that Li ₂ O oxide has a high sensitivity to water, reacts violently with the formation of lithium hydroxide, which makes it dangerous to use in the curable film-forming compositions of the present invention. The expression "practically free" means that these materials are not essential to the composition, and therefore the curable film-forming composition does not contain these materials in any significant or significant amount. If present, then only as incidental impurities in an amount, usually less than 0.1 percent by weight, based on the total weight of solids in the curable film-forming composition.

Curable film-forming compositions of the present invention comprising: (1) a curable, organic film-forming binder component (i.e., (a) a resin component and (b) a curing agent component) and (2) a corrosion inhibiting component can be prepared and stored prior to use. in the form of a one-pack composition. The expression "one-pack composition" shall mean such a composition in which all of the coating components are stored in one container after production, during storage, and the like. A typical one-package coating can be applied to a substrate and cured using any conventional technique such as heat, compressed air, radiation curing, and the like. For some coatings, such as environmentally curing coatings, it is impractical to store them in the same package, rather they should be stored as coatings in a group package to prevent components from curing before use. The expression “multi-pack coatings” means coatings in which the various components are stored separately, immediately prior to application. In addition, the coatings of the invention can be multiple pack coatings such as dual pack coatings.

Thus, components (a) and (b) can be provided in a single package (1K) or in multiple packages, for example in a two-package system (2K). Components of organic film-forming binders (1) are often provided in separate packages and mixed immediately prior to interaction. When the reaction mixture is in a group packing system, the corrosion inhibiting component (2) can be present either in one or both of the individual components (a) and (b) and / or as an additional separate component of the package.

The curable film-forming composition of the present invention may further include optional components that are commonly used in such compositions. For example, the composition may further comprise a blocked amine light stabilizer to resist the effects of UV radiation. Said blocked amine light stabilizers include those described in US Pat. No. 5,260,135. When light stabilizers are used, they are present in the composition in an amount of from 0.1 to 2 percent by weight, based on the total weight of solid resins in the film-forming composition. Other optional additives can be added such as colorants, plasticizers, abrasion resistant particles, film hardeners, flow control agents, thixotropic agents, rheological modifiers, aggregates, catalysts, antioxidants, biocides, antifoams, surfactants, wetting agents, dispersion aids, adhesion promoters, UV absorbers and stabilizers, stabilizing agents, organic co-solvents, reactive diluents, grinding media, and other conventional adjuvants, or combinations thereof. Used in the invention, the term "colorant" is defined in US patent No. 2012/0149820, paragraphs 29 to 38, the cited fragments of which are included in the invention by reference.

"Abrasion resistant particles" are those particles that, when used in a coating, will provide the coating with some level of abrasion resistance when compared to the same coating without particles. Suitable abrasion resistant particles include organic and / or inorganic particles. Examples of suitable organic particles include, but are not limited to, diamond particles such as diamond dust particles and particles formed from carbide materials; examples of carbide particles include, but are not limited to, titanium carbide, silicon carbide, and boron carbide. Examples of suitable inorganic particles include, but are not limited to, silica; aluminium oxide; aluminum silicate; aluminosilicate; alkaline aluminosilicate; borosilicate glass; nitrides including boron nitride and silicon nitride; oxides including titanium dioxide and zinc oxide; quartz; nepheline syenite; zirconium dioxide, such as zirconium oxide; baddeleyite; and eudialyte. Particles of any size can be used, as mixtures of different particles and / or particles of different sizes.

As used herein, the terms “adhesion promoters” and “adhesion promoting component” refer to any material that, when included in the composition, improves the adhesion of the coating composition to a metal substrate. Such an adhesion promoting component often contains free acid. As used herein, the term "free acid" means organic and / or inorganic acids that are formulated as separate components of the composition as opposed to any acids that can be used to form the polymer that may be present in the composition. The free acid may include tannic acid, gallic acid, phosphoric acid, phosphorous acid, citric acid, malonic acid, derivatives thereof, or mixtures thereof. Suitable derivatives include esters, amides, and / or metal complexes of these acids. Frequently, the free acid includes phosphoric acid, for example, 100 percent phosphoric acid, superphosphoric acid, or aqueous solutions thereof such as 70 to 90 percent phosphoric acid.

In addition to or instead of these free acids, other suitable adhesion promoting components are metal phosphates, organic phosphates, and organic phosphonates. Suitable organic phosphates and organic phosphonates include those described in US Pat. No. 6,440,580 at column 3, line 24 to column 6, line 22, in US Pat. No. 5,294,265 at column 1, line 53 to column 2, line 55, and in US No. 5,306,526 in column 2 line 15 to column 3, line 8, the cited fragments of which are included in the invention by reference. Suitable metal phosphates include, for example, zinc phosphate, iron phosphate, manganese phosphate, calcium phosphate, magnesium phosphate, cobalt phosphate, zinc iron phosphate, zinc manganese phosphate, zinc calcium phosphate, including those described in US Patent Nos. 4,941,930 , 5,238,506, and 5,653,790. As stated above, in certain situations, phosphates are excluded.

The adhesion promoting component may include phosphated epoxy resins. Such resins can include the product of the interaction of one or more epoxy-functionalized materials and one or more materials containing phosphorus. Non-limiting examples of such materials that are suitable for use in the present invention are described in US Pat. No. 6,159,549 at column 3, lines 19 to 62, the cited fragments of which are incorporated herein by reference.

In addition, the curable film-forming composition of the present invention may contain alkoxysilane adhesion promoting agents, for example, acryloxyalkoxysilanes such as γ-acryloxypropyltrimethoxysilane and methacrylatoalkoxysilanes such as γ-methacryloxypropyltrimethoxysilane such as γ-siloxymethoxysilane, as well as epoxypropyltrimethoxysilane. Examples of suitable alkoxysilanes are described in US Pat. No. 6,774,168 at column 2, lines 23 to 65, the cited portions of which are incorporated herein by reference.

Typically, the adhesion promoting component is present in the coating composition in an amount ranging from 0.05 to 20 percent by weight, such as at least 0.05 percent by weight or at least 0.25 percent by weight, and at most 20 percent by weight, or at most 15 percent by weight, with ranges such as 0.05 to 15 percent by weight, 0.25 to 15 percent by weight, or 0.25 to 20 percent by weight weight, weight percentages are based on the total weight of solid resins in the composition.

In addition, the coating compositions of the present invention may contain, in addition to any previously described corrosion resistant particles, conventional non-chromium corrosion resistant particles. Suitable conventional corrosion-resistant chromium-free particles include, but are not limited to, iron phosphate, zinc phosphate, calcium ion exchange silicon dioxide, colloidal silicon dioxide, synthetic amorphous silicon dioxide, and molybdates such as calcium molybdate, zinc molybdate, molybdate barium, strontium molybdate, and mixtures thereof. A suitable calcium ion exchange silica is commercially available from W. R. Grace & Co. under the names SHIELDEX AC3 and / or SHIELDEX. C303. A suitable amorphous silica is available from W. R. Grace & Co. as SYLOID. A suitable hydroxyl zinc phosphate is commercially available from Elementis Specialties, Inc. as NALZIN 2. These conventional non-chromium corrosion resistant pigments typically contain particles having an approximate size of 1 micron or larger. These particles may be present in the coating compositions of the present invention in an amount ranging from 5 to 40 percent by weight, for example at least 5 percent by weight, or at least 10 percent by weight, and at most 40 percent by weight, or at most 25 percent by weight, ranging from 10 to 25 percent by weight, with percentages by weight being based on the total weight of solids in the composition.

In addition, the coatings of the invention may contain one or more organic inhibitors. Examples of such inhibitors include, but are not limited to, heterocyclic compounds containing sulfur and / or nitrogen, examples of which include thiophene, hydrazine and its derivatives, pyrrole and its derivatives. When used, organic inhibitors can be present in the coating compositions in an amount ranging from 0.1 to 20 percent by weight, such as from 0.5 to 10 percent by weight, with percentages by weight based on the total solids in the composition.

In addition, the present invention provides a metal substrate at least partially coated with the curable film-forming composition described above.

The metal substrates used in the present invention include ferrous metals, non-ferrous metals, and combinations thereof. Suitable ferrous metals include iron, steel, and their alloys. Non-limiting examples of useful steel materials include cold rolled steel, pickled steel, steel surface treated with any zinc metal, zinc compounds and zinc alloys (including electrogalvanized steel, hot dipped galvanized steel, annealed galvanized steel, and zinc alloy plated steel) and / or zinc-iron alloys. In addition, aluminum, aluminum alloys, zinc-aluminum alloys such as galfan, galvalum, aluminum coated steel and aluminum alloy coated steel substrates can be used. Steel substrates (such as cold rolled steel or any of the steel substrates listed above) coated with weldable organic coatings enriched in zinc or iron phosphide are also suitable for use in the present invention. Such weldable coating compositions are described in US Pat. Nos. 4,157,924 and 4,186,036. Cold rolled steel is also suitable after pretreatment with an appropriate solution known in the art, such as a metal phosphate solution, an aqueous solution containing at least one metal from groups IIIB or IVB, an organic phosphate solution, an organic phosphonate solution, and combinations thereof which are discussed below. Examples of aluminum alloys include those used in the automotive or aerospace industries such as the 2000, 6000, or 7000 series aluminum alloys; specific examples are alloys 2024, 7075, 6061. The alloys may be uncoated or they may contain a coating layer on one or more surfaces, the coating layer being composed of a different aluminum alloy than the monolithic substrate alloy below the coating layer.

Alternatively, the substrate may comprise more than one metal or metal alloy, in which the substrate may be a combination of two or more metal substrates assembled together, such as hot-dip galvanized steel bonded to an aluminum substrate. The substrate can form part of the vehicle. The term "vehicle" is used in the invention in its broadest sense and includes all types of vehicles, manual and non-manual, such as (but not limited to) aircraft, helicopters, radio-controlled aircraft, cars, carts, buses, vans, golf carts, motorcycles, bicycles, railroad carts, tanks and the like. It should be understood that the coated portion of the vehicle according to the invention may vary depending on the application of the coating. Often the substrate is part of the aircraft.

The curable film-forming composition can be applied directly to the metal substrate when there is no intermediate coating between the substrate and the curable film-forming composition. This means that the substrate may be stripped as described below, or may have been pre-treated with one or more compositions as described below, however, typically the substrate is not coated with any coating composition, such as an electrolytic coating composition or a primer composition, prior to application. curable film-forming composition of the present invention.

As indicated above, the substrates used can be uncoated metal substrates. The term “uncoated” means a parent metal substrate that has not been pretreated with any processing compositions such as conventional phosphating solutions, heavy metal washing liquid, etc. In addition, uncoated metal substrates that are used in the present invention may constitute cut edge

a substrate that is treated and / or coated differently from the rest of the surface. Alternatively, the substrates can be treated in one or more steps known in the art prior to application of the curable film-forming composition.

The substrate can optionally be cleaned using conventional techniques and materials. These can include mild or strong alkaline cleaning agents that are commercially available and are traditionally used in metal pretreatment processes. Examples of alkaline cleaning agents include Chemkleen 163 and Chemkleen 177, which are available from PPG Industries, Pretreatment and Specialty Products. These cleaning agents usually follow and / or precede the aqueous wash liquid. In addition, the surface can be washed with an aqueous acidic solution after or instead of cleaning with an alkaline cleaning agent. Examples of washing solutions include mild or strong acidic cleaning agents such as dilute nitric acid solutions, which are commercially available and traditionally used in metal pretreatment processes.

According to the present invention, at least a portion of the cleaned surface of the aluminum substrate can be deoxygenated mechanically or chemically. As used herein, the term “deoxygenation” means removing the oxide layer formed on the surface of the substrate in order to promote uniform deposition of the pretreatment composition (described below), as well as to promote adhesion of the pretreatment coating composition to the substrate surface. Suitable deoxidizers are familiar to those skilled in the art. Typical mechanical deoxidizers can provide an even roughening of the substrate surface, for example using an abrasive or cleaning pad. Typical chemical deoxidizers include, for example, acid-based deoxidizers such as phosphoric acid, nitric acid, fluoroboric acid, sulfuric acid, chromic acid, hydrofluoric acid, and ammonium bifluoride, or Amchem 7/17 reducing agents (available from Henkel Technologies, Madison Heights, MI), OAKITE DEOXIDIZER LNC (commercially available from Chemetall), TURCO DEOXIDIZER 6 (commercially available from Henkel), or combinations thereof. Often, the chemical deoxidizer contains a carrier, usually an aqueous medium, so that the deoxidant can be in the form of a solution or dispersion in the carrier; in this case, the solution or dispersion can be brought into contact with the substrate using any of the numerous known techniques such as dipping or dipping, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roller coating.

The metal support may optionally be pretreated with any suitable solution known in the art, such as a metal phosphate solution, an aqueous solution containing at least one metal from groups IIIB or IVB, an organic phosphate solution, an organic phosphonate solution, and a combination thereof ... Pretreatment solutions can be virtually free of environmentally harmful heavy metals such as chromium and nickel. Suitable phosphate conversion coating compositions can be any compositions that are known in the art and do not contain heavy metals. Examples include zinc phosphate, which is most commonly used, iron phosphate, manganese phosphate, calcium phosphate, magnesium phosphate, cobalt phosphate, zinc-iron phosphate, zinc-manganese phosphate, zinc-calcium phosphate, and other types of layers that may contain one or several polyvalent cations. Phosphating compositions are known to those skilled in the art and are described in US Pat. Nos. 4,941,930, 5,238,506 and 5,653,790.

Specified in the invention transition metals from groups IIIB or IVB and rare earth metals are those elements that are included in these groups in the periodic table of the elements of CAS, depicted, for example, in Handbook of Chemistry and Physics, 63rd edition (1983).

Typical compounds of transition metals from groups IIIB and IVB and compounds of rare earth metals are compounds of zirconium, titanium, hafnium, yttrium and cerium, and mixtures thereof. Typical zirconium compounds can be selected from hexafluorozirconic acid, its alkali metal salts and ammonium salts, ammonium zirconium carbonate, zirconyl nitrate, zirconium carboxylates and zirconium hydroxide carboxylates such as hydrofluorozirconic acid, zirconium acetate, zirconium oxalate, zirconium glyactate ammonium-zirconium, ammonium-zirconium citrate, and mixtures thereof. Hexafluorozirconic acid is the most commonly used. An example of a titanium compound is titanium fluoride and its salts. An example of a hafnium compound is hafnium nitrate. An example of a compound of yttrium is yttrium nitrate. An example of a cerium compound is cerium nitrate.

Typical compositions that can be used in the pretreatment step include non-conductive organic phosphate and organic phosphonate pretreatment compositions such as those described in US Pat. Nos. 5,294,265 and 5,306,526. These organic phosphates or organic phosphonates for pretreatment are commercially available from PPG Industries, Inc. under the name NUPAL®.

In the aerospace industry, anodizing surface treatments as well as chromium-based conversion coatings and pretreatments are often applied to aluminum alloy substrates. Examples of anodizing surface treatment include chromic acid anodizing, phosphoric acid anodizing, boric acid-sulfuric acid anodizing, tartaric acid anodizing, sulfuric acid anodizing. Chromium-based conversion coatings may include hexavalent chromium-type coatings such as Bonderite® M-CR1200 from Henkel and trivalent chromium such as Bonderite® M-CR T5900 from Henkel.

The curable film-forming composition of the present invention can be applied to a substrate using conventional techniques. The use of a spray applied or electrodeposited primer or filler primer under the curable film-forming composition of the present invention is generally not required due to the excellent corrosion resistance provided by the composition of the present invention.

The coating compositions of the present invention can be used individually as a protective coating, or can serve as a single or multi-layer coating. Alternatively, the compositions of the present invention can be in combination, such as a primer, backcoat and / or topcoat. Thus, the present invention provides a coated multilayer metal substrate. The specified multi-layer coated substrate contains:

(a) a metal substrate;

(b) a curable film-forming composition applied to said metal substrate, the curable film-forming composition comprising:

(1) a curable, organic film-forming binder component; and

(2) a corrosion inhibiting component that contains lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5 wt.% Lithium, based on the total weight of solid resins in the curable film-forming composition; and

(c) a layer of additional coating applied over at least a portion of the curable film-forming composition. In specific examples, the curable film-forming composition described above is a primer applied to a substrate, and an additional coat applied over the curable film-forming composition is a topcoat composition. In another example, the curable film-forming composition is a primer and the additional coat is a primer-filler coat. In certain examples, the additional coating layer comprises a fluoropolymer and / or a polyurethane polymer as described above.

The curable film-forming composition of the present invention is often used as a corrosion-resistant primer. As indicated, the present invention may relate to primer compositions for coating a metal substrate, such as "etch primers". As used herein, the term "primer coating composition" refers to coating compositions from which a tie layer can be deposited onto a substrate. In some industries or for certain substrates, a primer is applied to a surface prepared for a protective or decorative coating system. In other industries or substrates, no other coat is applied over the primer. For example, a surface of a substrate that has limited or no external impact may have a primer with no other layer on top. As used herein, the term "etch primer" refers to a primer coating composition that includes an adhesion promoting component such as a free acid, as described in more detail above.

Suitable topcoats (backsheet, clearcoats, pigmented monolayer coats, and color-plus-clear composite compositions) include any coatings known in the art, and each of them may be water-based, solvent-based, or powdered. The topcoat typically includes a film-forming resin, a crosslinking material, and a pigment (in a colored backing or multi-layer coating). Non-limiting examples of suitable backsheet compositions include compositions prepared in water such as those described in US Patent Nos. 4,403,003; 4,147,679; and 5,071,904. Suitable clear layered compositions include those described in US Pat. Nos. 4,650,718; 5,814,410; 5,891,981; and document WO 98/14379.

The additional coating layer applied over the curable film-forming composition may include a corrosion inhibiting component comprising lithium silicate, magnesium oxide, and / or an azole; that is, the additional coating layer applied over the curable film-forming composition may include a corrosion inhibiting component containing at least one of lithium silicate, magnesium oxide, and an azole. In these embodiments, the additional coating layer may be the same or different from the curable film-forming composition. The layer may be different from the curable film-forming composition, although it still falls within the protection scope of the curable film-forming composition of the present invention; for example, the curable film-forming binder component of the additional coating layer may be different from the first layer, but it may still be a composition according to the present invention.

In addition, the present invention discloses a coated multilayer metal substrate that comprises:

(a) a metal substrate;

(b) a first curable film-forming composition applied to said metal substrate, wherein the first curable film-forming composition comprises:

(1) a curable, organic film-forming binder component; and

(2) a component that inhibits corrosion; and

(c) a second curable film-forming composition applied over at least a portion of the first curable film-forming composition; in which the second curable film-forming composition contains:

(1) a curable, organic film-forming binder that is the same as or different from the curable, organic film-forming binder in the first curable film-forming composition; and

(2) a corrosion inhibiting component that is the same or different from the corrosion inhibiting component in the first curable film-forming composition; and where the corrosion inhibiting component (2) in each of the first and second curable film-forming compositions independently comprises:

(i) a lithium compound containing lithium silicate and / or a lithium salt; (ii) magnesium oxide; and / or (iii) an azole. Suitable lithium salts include lithium carbonate, lithium oxalate, lithium phosphate, lithium sulfate, lithium tetraborate, lithium acetate, lithium zirconate, and lithium molybdate. Combinations of lithium compounds are also suitable.

In specific examples, the following combinations are contemplated: the lithium compound can be in one layer (in the first or second layer), and the thiazole in another layer. The lithium compound can be in one layer (first or second layer) and diazole in another layer. The lithium compound can be in one layer (first or second layer) and imidazole in another layer. The lithium compound can be in one layer (first or second layer) and oxazole in another layer. The lithium compound can be in one layer (first or second layer) and tetrazole in another layer. The lithium compound can be in one layer (first or second layer) and triazole in another layer. In each of the above examples, magnesium oxide can be used in combination with a lithium compound and / or an azole.

In additional specific examples, magnesium oxide can be in one layer (first or second layer) and thiazole in another layer. Magnesium oxide can be in one layer (first or second layer) and diazole in another layer. Magnesium oxide can be in one layer (first or second layer) and imidazole in another layer. Magnesium oxide can be in one layer (first or second layer) and oxazole in another layer. Magnesium oxide can be in one layer (first or second layer) and tetrazole in another layer. Magnesium oxide can be in one layer (first or second layer) and triazole in another layer.

In certain additional examples, it may be desirable that each of the lithium compounds, magnesium oxide, and azole are all present in the coated multilayer metal substrate; that is, all three corrosion inhibitors are present in the coating package. The inhibitors can be present in each film-forming composition in any combination, provided that at least one inhibitor is present in each coating layer. For example, a lithium compound and magnesium oxide can be in one layer (first or second layer) and thiazole in another layer. The lithium compound and magnesium oxide can be in one layer (first or second layer) and diazole in another layer. The lithium compound and magnesium oxide can be in one layer (first or second layer) and imidazole in another layer. The lithium compound and magnesium oxide can be in one layer (first or second layer) and oxazole in another layer. The lithium compound and magnesium oxide can be in one layer (first or second layer) and tetrazole in another layer. The lithium compound and magnesium oxide can be in one layer (first or second layer) and triazole in another layer. The lithium compound can be in one layer (first or second layer) and thiazole and magnesium oxide in another layer. The lithium compound can be in one layer (first or second layer) and diazole and magnesium oxide in another layer. The lithium compound can be in one layer (first or second layer) and imidazole and magnesium oxide in another layer. The lithium compound can be in one layer (first or second layer) and oxazole and magnesium oxide in another layer. The lithium compound can be in one layer (first or second layer) and tetrazole and magnesium oxide in another layer. The lithium compound can be in one layer (first or second layer), and triazole and magnesium oxide in another layer.

In said coated multilayer metal substrate of the present invention, the metal substrate may be any of those described above. Likewise, each of the first and second curable film-forming compositions may independently contain any of the curable, organic film-forming binders described above. Further, for example, in this coated multilayer metal substrate, the curable film-forming composition may be a primer coating applied to the substrate, and a second coating layer applied over the first curable film-forming composition may constitute a topcoat composition. In another example, the first curable film-forming composition can be a primer coat and the second coat can be a second primer, such as a putty primer.

The coating compositions of the present invention can be applied to a substrate using known techniques such as dipping or dipping, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roller coating. Conventional air spraying and electrostatic spraying techniques and equipment, either manually or automatically, can be used.

After the composition is applied to a substrate, a film is formed on the surface of the substrate by the movement of a solvent, that is, an organic solvent and / or water, from the film by heating or air drying. Suitable drying conditions will depend on the type of particular composition and / or application, however, in some cases, a drying time of about 1 to 5 minutes, at a temperature of about 70 to 250 ° F (27 to 121 ° C) will be sufficient. If desired, more than one coating layer of the composition according to the invention can be applied. Usually between coats, the previously applied layer is cured; that is, it is exposed to environmental conditions for a given period of time. Typically, the coating thickness is 0.1 to 3 mils (2.5 to 75 microns), such as 0.2 to 2.0 mils (5.0 to 50 microns). The coating composition can then be heated. In the curing step, the solvents are removed and the crosslinking components of the composition are crosslinked. Occasionally, heating and curing operations are performed at temperatures ranging from 70 to 250 ° F (27 to 121 ° C), but lower or higher temperatures can be used if necessary. As noted previously, the coatings of the present invention can also be cured without additional heating or drying steps. In addition, the first coating composition can be applied and then the second “wet-on” is applied to it. Alternatively, the first coating composition can be cured before one or more additional coating layers are applied.

The coated metal substrates of the present invention can exhibit excellent corrosion resistance as determined by a salt spray corrosion test.

It can be said that each characteristic and the examples described above, and their combinations, are included in the scope of the present invention. Thus, the present invention is limited to the following non-limiting aspects: in a first aspect, the present invention provides a curable film-forming composition that contains: (1) a curable, organic film-forming binder component; and (2) a corrosion inhibiting component containing lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5 wt.% lithium, based on the total weight of solid resins in the curable film-forming composition.

In a second aspect, in the composition according to the first aspect described above, the organic film-forming binder component (1) comprises (a) a resin component containing epoxy functional groups; and (b) an amine functional curing agent component.

In a third aspect, in any of the compositions according to any of the first or second aspect described above, the lithium silicate comprises lithium orthosilicate and / or lithium metasilicate.

In a fourth aspect, in any of the compositions according to any aspect described above, the corrosion inhibiting component (2) further comprises magnesium oxide and / or an azole.

In a fifth aspect, there is provided a metal substrate at least partially coated with any curable film-forming composition according to any one of the above first to fourth aspects.

In a sixth aspect, there is provided a coated metal substrate according to the fifth aspect described above, wherein the curable film-forming composition is applied directly to the metal substrate, with no intermediate coating between the substrate and the curable film-forming composition.

In a seventh aspect, there is provided a coated metal substrate according to any one of the above fifth or sixth aspect, wherein the metal substrate comprises aluminum.

In an eighth aspect, there is provided a coated metal substrate according to any one of the above fifth to seventh aspects, wherein the metal substrate is part of an aircraft.

In a ninth aspect, there is provided a coated metal substrate according to any of the fifth to eighth aspects above, further comprising an additional coating layer applied over at least a portion of the curable film-forming composition. In certain aspects, the additional coating layer can include a fluoropolymer and / or a polyurethane polymer.

In a tenth aspect, there is provided a coated metal substrate according to the aforementioned ninth aspect, wherein the curable film-forming composition is a primer and the additional coating layer is a topcoat composition.

In an eleventh aspect, there is provided a coated metal substrate according to the above ninth aspect, wherein the curable film-forming composition is a colored substrate layer and the additional coating layer is a transparent colorless layer composition.

In a twelfth aspect, there is provided a coated metal substrate according to any of the ninth to eleventh aspects above, wherein the additional coating layer comprises a corrosion inhibiting component comprising lithium silicate, magnesium oxide and / or azole.

In a thirteenth aspect of the present invention, there is provided a coated multilayer metal substrate comprising: (a) a metal substrate; (b) a first curable film-forming composition applied to said metal substrate, wherein the first curable film-forming composition comprises: (1) a curable, organic film-forming binder component; and (2) a component that inhibits corrosion; and (c) a second curable film-forming composition applied over at least a portion of the first curable film-forming composition; where the second curable film-forming binder composition contains: (1) a curable, organic film-forming and binder component that is the same as or different from the curable, organic film-forming binder component in the first curable film-forming composition; and (2) a corrosion inhibiting component that is the same or different from the corrosion inhibiting component in the first curable film-forming composition; and where component (2), corrosion inhibiting, in each of the first and second curable film-forming composition, independently contains (i) a lithium compound containing lithium silicate and / or a lithium salt; (ii) magnesium oxide; and / or (iii) an azole.

In a fourteenth aspect, there is provided a coated multilayer metal substrate according to the above thirteenth aspect, wherein each of lithium silicate, magnesium oxide, and an azole is present.

In a fifteenth aspect, there is provided a coated multilayer metal substrate according to the above thirteenth aspect, wherein the corrosion inhibiting component (2) in the first curable film-forming composition (b) comprises magnesium oxide, wherein the corrosion-inhibiting component (2) in the second curable film-forming composition composition (c) contains a lithium compound (i) and / or azole (iii).

In a sixteenth aspect, there is provided a coated multilayer metal substrate according to any of the above thirteenth to fifteenth aspects, further comprising (d) an additional film-forming composition applied over at least a portion of the second curable film-forming composition.

The invention will be further described with reference to the following examples. Unless otherwise noted, all parts are by weight.

Examples of

Table 1 provides a description of the materials used in the implementation of the examples.

Component Description Provider Ancamide® 2569 Polyamide curing agent Air Products Ancamide® 2445 Polyamide curing agent Air Products Ancamine® 2432 Polyamine curing agent Air Products Ancamine® 1895 Polyamine curing agent Air Products Gaskamine® 328 Polyamine curing agent Mitsubishi Gas Chemical Ancamine® K54 Catalyst Air Products Ti-Pure® R-706-11 Titanium dioxide DuPont Bayferrox® 3920 Iron oxide; C.I. pigment yellow 42 Lanxess Corp. Gasil® IJ35 Fine particles Ineos Silicas America Blanc Fix (Micro) Barium sulphate Sachtleben Chemie GmbH ACEMATT® OK412 silicon dioxide treated with paraffin Evonik Degussa Oxsol® 100 4-chlorotrifluoromethylbenzene Rhodia Epon® 828 bisphenol A / epichlorohydrin resin Momentive Erisys® GA-240 Polyfunctional epoxy resin CVS Specialty Chemicals DEN® 431 novolac epoxy resin Dow chemical Eponex® 1510 Hydrogenated Bisphenol A / Epichlorohydrin Resin Momentive-Hexion Epon® TM811 modified epoxy resin Momentive Silquest® A187 Epoxysilane Momentive Silquest® A189 3-mercaptopropyltrimethoxysilane (3-MPTMS) Momentive Solution DBTDL 10% solution of DABCO T12 in xylene Air Products (as DABCO T12) Nano magnesium oxide MgO: average particle size 20 nm, surface area 50 m ² / g Nano Structured and Amorphous Materials Maglite® Y MgO: average particle size 10 μm, surface area 55 m ² / g Hallstar Magchem® 10-325 MgO: average particle size 10 μm, surface area 3 m ² / g Martin Marietta Magnesia Specialties Lithium Orthosilicate Lithium Orthosilicate Rockwood Lithium Lithium metasilicate Lithium metasilicate Rockwood Lithium Lithium carbonate Lithium carbonate Rockwood Lithium Hybricor® 204 Organic (azole) /
inorganic hybrid
corrosion inhibitor WPC Technologies, Inc. Mercaptobenzothiazole 2-mercaptobenzothiazole (MBT) Americas International, Inc. Dimercaptothiadiazole 2,5-Dimercapto-1,3,4-thiadiazole (DMTD) Alfa aesar Benzotriazole Cobratec 99 / BZ (BZT) PMC Specialties Group Sodium Mercaptobenzothiazole 2-mercaptobenzothiazole sodium salt (NaMBT) TCI America BYK 358N Acrylate copolymer BYK Chemie CA1800CX Solvent mixture / Thinner PPG Aerospace PRC Desoto EAC-8 Metal conditioner PPG Aerospace / Eldorado Grinding medium Lot # 74582, minimum 85% Al ₂ O ₃ (16-20 mesh) Coors tek Turco 4215 NC-LT Alkaline cleaning agent Henkel Nitric acid (68-70%) Acid pickling agent Fisher Scientific Sulfuric acid (93-98%) Acid pickling agent Fisher Scientific Iron (III) sulfate pentahydrate Acid pickling agent Fisher Scientific Sodium hydroxide tablets Alkaline etchant Fisher Scientific Triethylamine Alkaline etchant Air Products Bostex 378 Alkaline etchant Akron dispersions Desmodur N 3300 Modified polyisocyanate Bayer CA8800 / B70846 Polyurethane (PU) Topcoat Component (PU Topcoat) PPG Industries CA8800Z Activating component of polyurethane topcoat PPG Industries CA8800CT Thinner for polyurethane topcoats PPG Industries CA9311 / F36173 Enhanced Performance Polyurethane Topcoat Component (PU AP Topcoat) PPG Industries CA9300 Enhanced Polyurethane Topcoat Activator PPG Industries

For all examples, the amount of each material is given in units of "gram by weight" unless otherwise indicated. Example 1 is a comparative example. (Note: all comparative examples are labeled “Comp.”). Examples 2-4 demonstrate the preparation of curable film-forming compositions according to the present invention.

Table 2. Comparison of compositions without inhibitor and with lithium orthosilicate (different contents)

Material Comp. example 1 Example 2 Example 3 Example 4 Component A r r r r Ancamide 2569 20.8 20.8 20.8 20.8 Ancamine 2432 13.8 13.8 13.8 13.8 Ancamine K-54 1.3 1.3 1.3 1.3 n-butyl alcohol 51.7 51.7 51.7 51.7 Xylene 6,3 6,3 6,3 6,3 Total 93.9 93.9 9.39 93.9 Component B r r r r Epon 828 65.8 65.8 65.8 65.8 Xylene 3.4 3.4 3.4 3.4 Oxsol 100 66.8 66.8 66.8 66.8 Silquest A-187 1.6 1.6 1.6 1.6 Ti-Pure R-706-11 100.0 95.0 90.0 85.0 Lithium Orthosilicate 0 5.0 10.0 15.0 Thinner CA1800CX 23.8 23.8 23.8 23.8 Total 261.4 261.4 261.4 261.4 Total mass of mixture 355.3 355.3 355.3 355.3

The coatings in examples 1-4 were prepared as follows:

For component A in each example, all materials are weighed into suitable containers and mixed thoroughly using an air motor and stirring paddle. In each component B example, all materials are weighed except for Silquest A-187 and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix each final component B mixture thoroughly. Prior to coating, the respective ratios of each total component A to total component B shown in Table 2 are compounded together, mixed thoroughly and an induction period is set between 30 and 60 minutes prior to application.

The coatings in Examples 1-4 were applied by spraying the panels to an uncoated 2024T3 aluminum alloy substrate to a dry film thickness of between 0.6 and 1.2 mils using an air blast gun. Prior to coating, the aluminum alloy substrate panels were processed as follows. The aluminum alloy panels were cleaned, wiped with methyl ethyl ketone, then processed as indicated in the table below.

Alkaline pickling and nitric / sulfuric acid pickling process Stage Process description Solution Time Temperature 1 Alkaline cleaning Turco cleaning solution 5 minutes 60-70 ° C 2 Flushing Deionized water (DI) 1 minute room 3 Air drying N / A * 0 to 12 hours 4 Alkaline etching Alkaline solution
etching 3 minutes room five Flushing Deionized water 1 minute room 6 DI flush with water gun Deionized water N / A * room 7 Removal of pickling sludge 30% nitric acid
in deionized water 0.25 to
1 minute room 8 Flushing Deionized water 1 room nine Acid pickling Decapitating solution
nitric / sulfuric acid 8 50-60 ° C ten Flushing Deionized water 1 room eleven Flushing Deionized water 1 room 12 DI flush with water gun Deionized water N / A * room 13 Air drying N / A * from 1 to 3 hours. room

* does not apply

The solutions used for the alkaline pickle / nitric / sulfuric acid pickling process are listed below. The techniques are outlined below.

Loading Turco cleaning solution g / ml 1 Turco 4215 NC LT 2 Deionized water Up to a total volume of 1000 ml

The Turco 4215 NC-LT solution is weighed into a 1000 ml beaker and deionized water is added to make 1000 ml of solution. The mixture is stirred until complete dissolution.

Loading Alkaline pickling solution g / ml 1 NaOH granules 2 Deionized water 3 Bostex 378 60 ml 4 Triethylamine 40 ml five Deionized water 3100 ml

Load No. 2 is weighed into a glass vessel in which 4000 ml can be placed; load No. 1 is weighed in a separate container; charge # 1 is slowly added to charge # 2 with stirring; an exothermic reaction occurs. The solution is allowed to cool for 15 minutes; the remaining downloads are added sequentially with thorough mixing between additions.

Loading Decapitating solution of nitric / sulfuric acid g / ml 1 Deionized water 500 ml 2 Sulfuric acid (93-98%) 3 Nitric acid (68-70%) 4 Iron (III) sulfate • 5H ₂ O five Deionized water up to a total volume of 1000 ml

Load No. 1 is placed in a 1000 ml beaker; charge # 2 and charge # 3 are weighed in two separate containers; loading # 2, followed by loading # 3, is slowly added to a 1000 ml beaker with stirring; an exothermic reaction occurs. Load # 4 is weighed into a separate container and slowly added to a 1000 ml beaker with stirring. After dissolution, add deionized water to a solution volume of 1000 ml.

Test panels coated with the compositions of Examples 1-4 are aged at ambient conditions for at least 7 days, after which a 10 cm by 10 cm “X” mark is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The scores in Table 3 were obtained after 840 hours of exposure for Examples 1-4. These panels are rated on the following scale:

Lettering Corrosion Test: Lower scores are best

Scores are given from 0 to 100, with the number representing the percentage of the inscribed area with visible corrosion.

Glossy character of the lettering: The best are the lower numbers

Scores are given from 0 to 100, with the number representing the percentage of the lettering that is dark / faded.

Bulges: Lower scores are best.

The total number of bulges near the decal and bulges away from the decal (i.e., the outer surface) is up to 30.

Maximum lettering bulge size: Lower numerical ratings are the best.

The size of the largest bulge next to the inscription is recorded as follows:

0 no swelling of the inscription

<1.25 mm The diameter of the largest bulge of the lettering is less than 1.25 mm

> 1.25 mm Diameter of largest lettering bulge - between 1.25 mm and 2.5 mm

> 2.5 mm The diameter of the largest bulge of the lettering is greater than 2.5 mm.

Table 3. Results of corrosion tests for examples 1-4

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size Comp. 1 No inhibitor 25 95 > 30 0 > 1.25 mm 2 1.2% Li as lithium orthosilicate 15 80 0 0 0 3 2.3% Li as lithium orthosilicate ten 75 0 0 0 4 3.5% Li as lithium orthosilicate ten 85 0 0 0

The corrosion data shown in Table 3 clearly show that the coatings of Examples 2, 3 and 4, which contain the corrosion inhibitor lithium orthosilicate at 1.2%, 2.3% and 3.5% lithium, respectively, provide a noticeable improved corrosion protection for the metal substrate compared to the comparative coating of Example 1, which does not contain a corrosion inhibitor. Evidence of improved corrosion protection is seen in the reduction in the number of areas of corrosion in the lettering, the more glossy nature of the lettering, and a decrease in coating blistering around the edges of the lettering.

Table 4. Comparison of compositions without inhibitor and with lithium orthosilicate (high content)

Material Comp. example 5 Comp. example 6 Component A r r Gaskamine 328 27.5 27.5 Ancamine K-54 1.3 1.3 n-butyl alcohol 51.7 51.7 Xylene 6,3 6,3 Ti-Pure R-706-11 18.9 18.9 Nano magnesium oxide 35.0 0 Lithium Orthosilicate 0 35.0 Total 140.7 140.7 Component B r D Erisys GA-240 49.2 49.2 DEN 431 21.6 21.6 Xylene 3.4 3.4 Silquest A-187 1.6 1.6 Oxsol 100 35.3 35.3 Thinner CA1800CX 23.8 23.8 Total 134.9 134.9 Total mass of mixture 275.6 275.6

Comparative coatings of examples 5 and 6 were prepared as follows:

For component A in each example, all materials are weighed and placed in glass vessels. Then, a dispersion medium is added to each vessel in an amount approximately equal to half the total weight of the mixture components. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. All final dispersions have a Hegman fineness greater than 6. In each example, for component B, all materials are weighed except for Silquest A-187 and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix each final component B mixture thoroughly. Prior to coating, the respective ratios of each total component A to total component B shown in Table 2 are compounded together, mixed thoroughly and an induction period is set between 30 and 60 minutes prior to application.

The coatings of Examples 5 and 6 were sprayed onto panels of an uncoated 2024T3 aluminum alloy substrate to a dry film thickness of between 0.6 and 1.5 mils using an air blast gun. Prior to coating, the aluminum alloy substrate panels were processed as follows. 2024T3 aluminum alloy panels were cleaned by wiping with methyl ethyl ketone followed by wet scrubbing using a very fine Scotchbrite® 7448 polishing pad and using EAC-8 conditioner to obtain a surface free of hydrophobic residues. After abrasion, quickly spray EAC-8 onto the surface of the panel and hold for 1 minute. Panels are washed thoroughly with water, wiped off with gauze to ensure the removal of oxides and allowed to dry for 1 to 3 hours before coating.

Test panels coated with the coatings of Examples 5 and 6 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” mark is drawn on the surface of the panel, which is deep enough to penetrate any cover the surface and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride, per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily monitoring).

The scores in Table 5 were obtained after 1920 hours of exposure for Examples 5 and 6. The panels were scored on the following scale:

Lettering Corrosion Test: Lower scores are best

Scores are given from 0 to 100, with the number representing the percentage of the inscribed area with visible corrosion.

Glossy character of the lettering: The best are the lower numbers

Scores are given from 0 to 100, with the number representing the percentage of the lettering that is dark / faded.

Bulges: Lower scores are best.

The total number of bulges near the decal and bulges away from the decal (i.e., the outer surface) is up to 30.

Maximum lettering bulge size: Lower numerical ratings are the best.

The size of the largest bulge next to the inscription is recorded as follows:

0 no swelling of the inscription

<1.6 mm The diameter of the largest bulge of the lettering is less than 1.6 mm

> 1.6 mm Diameter of largest lettering bulge - between 1.6 mm and 3.18 mm

> 3.18 mm The diameter of the largest bulge of the inscription is greater than 3.18 mm.

Table 5. Results of corrosion tests for examples 5 and 6

No.
example Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum size
blister lettering Comp. five 35% Comparative Corrosion Inhibitor ten 85 4 3 <1/16 ” Comp. 6 8.1% Li as
lithium orthosilicate 0 ten - * - * - *

*: the outer surface of the coated panel swells and the coating peels off the backing

The corrosion data in Table 5 clearly shows that when compared with a known inorganic chromium-free corrosion inhibitor at an increased concentration (8.1% lithium), lithium polysilicate provides an excellent improvement in corrosion protection, however, the coating film becomes sensitive to water, resulting in severe blistering and peeling of the coating from the metal substrate. Therefore, the content of lithium polysilicate should be kept below a level that can cause undesirable sensitivity to water for the coating film.

Table 6. Comparison of compositions with only MgO (comparative) versus MgO / Li-orthosilicate and MgO / Li-metasilicate (combinations according to the invention)

Material Comp. example 7 Example 8 Example 9 Component A r r r Ancamide 2569 20.8 20.8 20.8 Ancamine 2432 13.8 13.8 13.8 Ancamine K-54 1.3 1.3 1.3 n-butyl alcohol 29.3 29.3 29.3 Xylene 6,3 6,3 6,3 Total 71.5 71.5 71.5 Component B r r r Epon 828 65.8 65.8 65.8 Xylene 3.4 3.4 3.4 Oxsol 100 38.3 38.3 38.3 Silquest A-187 1.6 1.6 1.6 Ti-Pure R-706-11 65.0 60.0 65.0 nano magnesium oxide 10.0 10.0 10.0 Lithium Orthosilicate 0 5.0 0 Lithium metasilicate 0 0 5.0 n-butyl acetate 6.0 0 10.5 Thinner CA1800CX 23.8 23.8 23.8 Total 213.9 207.9 223.4 Total mass of mixture 285.4 279.4 294.9

The coatings in examples 7 to 9 were prepared as follows:

For component A in each example, all materials are weighed into suitable containers and mixed thoroughly using an air motor and stirring paddle. In each component B example, all materials are weighed except for Silquest A-187 and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 1.5 hours. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the Component B blends after the pigment dispersion process is complete. Then thoroughly mix each final component B blend. Prior to coating, the respective ratios of each total Component A to total Component B shown in Table 6 are compounded together, mixed thoroughly and an induction period is set between 30 and 60 minutes prior to application.

The coatings in Examples 7-9 were applied by spraying the panels with an uncoated 2024T3 aluminum alloy substrate to a dry film thickness of between 0.6 and 1.2 mils using an air blast gun. Prior to coating, the aluminum alloy backing panels were processed in the same manner as described for Examples 1-4.

Test panels coated with the compositions of Examples 7 to 9 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The scores in Table 7 were obtained after 1128 hours of exposure for Examples 7-9. The panels were scored according to the same scale used for Examples 1-4.

Table 7. Results of corrosion tests for examples 7 - 9

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum size
blister lettering Comp. 7 10% MgO 25 90 nineteen 0 <1.25 mm 8 10% MgO + 1.2% Li as lithium orthosilicate five 80 0 0 0 nine 10% MgO + 0.8% Li as lithium metasilicate ten 75 4 0 <1.25 mm

The corrosion data shown in Table 7 clearly show that coatings that contain the corrosion inhibitors lithium polysilicate, in addition to MgO, provide improved corrosion protection for the metal substrate compared to MgO alone. Evidence of improved corrosion protection is seen in the reduction in the number of areas of corrosion in the lettering, the more glossy nature of the lettering, and a decrease in coating blistering around the edges of the lettering.

Table 8. Uniscoating (no inhibitor versus lithium silicate + MgO)

Material Comp. example 10 Example 11 Component A r r Ancamide 2445 41.1 41.1 Ancamine 1895 8.8 8.8 Ancamine K-54 1.8 1.8 n-butyl alcohol 24.1 24.1 Xylene 5.9 5.9 Ti-Pure R-706-11 74.5 25.4 Silicon dioxide Gasil U35 4.9 4.9 Barium sulphate (micro) 13.1 13.1 Total 174.2 125.1 Component B r r Eponex 1510 60,7 60,7 n-amyl methyl ketone 30.4 30.4 BYK 385N 2.0 2.0 Silquest A-187 5.1 5.1 nano magnesium oxide 0 44.2 Lithium Orthosilicate 0 5.0 Bayferrox 3920 2.6 2.6 Total 100.8 150.0 Thinner component r r n-amyl methyl ketone 16.0 16.0 1: 1: 1 n-butyl alcohol: acetone: n-butyl acetate 6.0 Total 16.0 22.0 Total mass of mixture 291.0 297.1

The coatings in examples 10-11 were prepared as follows:

For component A in each example, all materials are weighed and placed in glass vessels. Then, a dispersion medium is added to each vessel in an amount approximately equal to half the total weight of the mixture components. For component B in each example, all materials were weighed except Silquest A-187 and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials with each component are capped and then placed in the Lau Dispersing Unit for a 3 hour dispersion time. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix each final component B mixture thoroughly. Prior to coating, the respective ratios of each component A total to component B total shown in Table 8 are compounded together, mixed thoroughly and an induction period is set between 30 and 60 minutes prior to application.

The coatings in examples 10-11 were applied by spraying uncoated 2024T3 aluminum alloy backing panels to a dry film thickness of between 1.5 and 2.0 mils using an air blast gun. Prior to coating, the aluminum alloy backing panels were processed in the same manner as described for Examples 1-4.

Test panels coated with the compositions of Examples 10-11 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” mark is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The estimates given in Table 9 were obtained after 1104 hours of exposure. The panels are scored according to the same scale used for Examples 1-4.

Table 9. Results of corrosion tests for examples 10 - 11

No.
measure Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum
bulge size
lettering Comp. ten Uni-coating without inhibiting
corrosion torus 20 95 > 30 0 > 1.25 mm eleven Uniplating with 45% nano-MgO + 1.2% Li as lithium orthosilicate five 65 15 0 <1.25 mm

The corrosion data shown in Table 9 clearly show that uncoatings that contain the corrosion inhibitor lithium polysilicate, in addition to the magnesium oxide corrosion inhibitor, provide significantly improved corrosion protection for the metal substrate when compared to the same uncoating formulation without the corrosion inhibitor. Evidence of improved corrosion protection is seen in the reduction in the number of areas of corrosion in the lettering, the more glossy nature of the lettering, and a decrease in coating blistering around the edges of the lettering.

Table 10. Multi-layer coating (first coating containing lithium silicate + second coating without inhibitor), comparative examples 12 and 14, and examples 13 and 15-17

Material Comp. example 12 Example 13 Comp. example 14 Example 15 Example 16 Example 17 First coating Component A r r r r r r Ancamide 2569 20.8 20.8 20.8 20.8 20.8 20.8 Ancamine2432 13.8 13.8 13.8 13.8 13.8 13.8 AncamineK-54 1.3 1.3 1.3 1.3 1.3 1.3 n-butyl alcohol 29.3 29.3 29.3 29.3 29.3 29.3 Xylene 6,3 6,3 6,3 6,3 6,3 6,3 Total 71.5 71.5 71.5 71.5 71.5 71.5 Component B r r r r r r Epon 828 65.8 65.8 65.8 65.8 65.8 65.8 Xylene 3.4 3.4 3.4 3.4 3.4 3.4 Oxsol 100 38.3 38.3 38.3 38.3 38.3 38.3 Silquest A-187 1.6 1.6 1.6 1.6 1.6 1.6 Ti-Pure R-706-11 75.0 70.0 75.0 70.0 60.0 60.0 nano magnesium oxide 0 0 0 0 10.0 10.0 Lithium Orthosilicate 0 5.0 0 5.0 5.0 5.0 Thinner CA1800CX 23.8 23.8 23.8 23.8 23.8 23.8 Total 207.9 207.9 207.9 207.9 207.9 207.9 Total mass of mixture 279.4 279.4 279.4 279.4 279.4 279.4 Second cover Component A ml ml ml ml ml ml CA8800 / B70846 one hundred one hundred one hundred CA9311 / F36173 150 150 150 Total one hundred one hundred 150 150 one hundred 150 Component B CA8800Z 50 50 50 CA9300 50 50 50 Total 50 50 50 50 50 50 Component C CA8800CT 50 50 50 Acetone 20 20 20 Total 50 50 20 20 50 20 Total mix volume 200 200 220 220 200 220

The coatings in examples 12-17 were prepared as follows:

First coat: For all examples, all materials for component A are weighed into suitable containers and mixed thoroughly using an air motor and stirring paddle. In each component B example, all materials are weighed except for Silquest A-187 and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials with each component are capped and then placed in the Lau Dispersing Unit for a 3 hour dispersion time. After 3.0 hours of dispersion time of component B in examples 13 and 15, additional medium is added to each vessel, approximately equal to the total weight of the components of the mixture. The vials are capped and then placed in the Lau Dispersing Unit for an additional 1 hour dispersing time. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix each final component B mixture thoroughly. Prior to coating, the respective ratios of each component A total to component B total shown in Table 8 are compounded together, mixed thoroughly and an induction period is set between 30 and 60 minutes prior to application. The first coatings for Examples 12-17 were sprayed onto uncoated 2024T3 aluminum alloy backing panels to a dry film thickness of between 0.7 and 1.3 mils using an air blast gun. Prior to coating, the aluminum alloy substrate panels were processed in the same manner as described for Examples 1-4. After applying the first coat in each example, the coated panels are stored at ambient conditions for 12 to 24 hours prior to applying the second coat of each example.

Second Coating: For Examples 12, 13, 14, 15, 16, and 17, the respective amounts of Component A and Component B shown in Table 10 for each example were added to appropriately sized containers and mixed thoroughly using an air motor and stirring paddle. Then add the appropriate amount of component C shown in table 10 for each example to the corresponding mixture of components A and B for each example. After thoroughly mixing the second coatings for Examples 12-17, they were sprayed onto panels pre-coated with the first coatings for Examples 12-17 such that every second coat of the example was applied to the corresponding first coat of the example (as shown in Table 10). Dry film thicknesses for second coats range from approximately 2.0 mils to 3.0 mils. The application of every second coat is carried out between the 10th and 60th minutes after the initial mixing of every final second coat.

Test panels fully coated with the coating of Examples 12-17 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The estimates in Table 11 were obtained after 1176 hours of exposure. The panels are scored according to the same scale used for Examples 1-4.

Table 11. Results of corrosion tests for examples 12 - 17

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size Comp. 12 First coat without inhibitor
Second PU topcoat without inhibitor 25 95 > 30 0 > 2.5 mm 13 First coverage -
1.2% lithium as lithium orthosilicate
Second PU topcoat without inhibitor 15 85 3 0 <1.25 mm Comp. fourteen First coat - no inhibitor
Second coat - PU AP top coat without inhibitor 40 90 > 30 0 > 2.5 mm 15 First coating is 1.2% lithium as lithium orthosilicate
Second PU AP coating - no inhibitor 25 85 4 0 <1.5 mm sixteen First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU-no inhibitor 20 90 4 0 <1.25 mm 17 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU AP - without inhibitor 25 85 five 0 <1.25 mm

The corrosion data shown in Table 11 clearly shows that multilayer coating systems in which the second coating does not contain a corrosion inhibitor (Examples 12-17), the corrosion resistance for aluminum alloy 2024 is significantly improved when the first coating contains only lithium orthosilicate (Examples 13 and 15) or in combination with magnesium oxide (examples 16 and 17), as compared to the first coating without corrosion inhibitor (examples 12 and 14). Evidence of improved corrosion protection is seen in the reduction in the number of areas of corrosion in the lettering, the more glossy nature of the lettering, and a decrease in coating blistering around the edges of the lettering.

Table 12. Multi-layer coating (first inhibitor coat + second inhibitor coat)

Material Example
18 Example
nineteen Example
20 Example
21 Example
22 Example
23 First coating Component A r r r r r r Ancamide 2569 20.8 20.8 20.8 20.8 18.4 20.8 Ancamine2432 13.8 13.8 13.8 13.8 12.2 13.8 AncamineK-54 1.3 1.3 1.3 1.3 1.3 1.3 n-butyl alcohol 29.3 29.3 29.3 29.3 24.2 29.3 Xylene 6,3 6,3 6,3 6,3 2.9 6,3 Nano magnesium oxide 15.0 15.0 Ti-Pure R-706-11 30.0 Total 71.5 71.5 71.5 71.5 104.0 86.5 Component B r r r r r Epon 828 65.8 65.8 65.8 65.8 60.1 65.8 Epon TM 8111 9.6 n-Butyl acetate 29.8 Xylene 3.4 3.4 3.4 3.4 1.5 3.4 Oxsol 100 38.3 38.3 38.3 38.3 38.3 Silquest A-187 1.6 1.6 1.6 1.6 1.6 1.6 Ti-Pure R-
706-11 70.0 70.0 60.0 60.0 40.0 Nano magnesium oxide 10.0 10.0 20.0 Maglite Y 15.0 MagChem 10-325 30.0 OK-412 silicon dioxide 10.0 Lithium Orthosilicate 5.0 5.0 5.0 5.0 Acetone 23.8 23.8 16.3 CA1800X 23.8 23.8 23.8 Total 207.9 207.9 207.9 207.9 173.9 192.9 Component C r r r r r r 1: 1: 1 n-
butyl alcohol: acetone: n-
butyl acetate 31.3 Total 0 0 0 0 31.3 0 r r r r r r Total mass of mixture 279.4 279.4 279.4 279.4 309.2 279.4

Material Example
18 Example
nineteen Example 20 Example 21 Example 22 Example 23 Second cover Component A ml ml ml ml r ml CA8800 / B70846 one hundred one hundred CA9311 / F36173 150 150 150 Joncryl 500 72.1 n-Butyl acetate 10.0 n-amyl methyl ketone 10.0 Gasil IJ35 4.9 Hybricor 204 20.0 Bayferrox 3920 2.6 Lithium Orthosilicate 5.0 Blanc-Fix (Micro) 13.1 Ti-Pure R-706-11 49.5 Total one hundred 150 one hundred 150 187.2 150 Component B ml ml ml ml r ml CA8800Z 50 50 CA9300 50 50 50 3-MPTMS 4.0 Solution DBTDL 0.8 Xylene 17.4 Desmodur N 3300 42.3 Total 50 50 50 50 64.5 50 Component C ml ml ml ml D ml CA8800CT 50 50 Acetone 20 20 20 Xylene 9.0 n-propyl methyl ketone 9.0 n-Butyl acetate 6.9 Hybricor 204 18 (d) 18 (d) 18 (d) 18 (d) 18 (d) Total ~ 68 ~ 38 ~ 68 ~ 38 24.9 ~ 38 ml ml ml ml r ml Total mass of mixture ~ 218 ~ 238 ~ 218 ~ 238 276.6 ~ 238

The coatings in examples 18-23 were prepared as follows:

First Coating: For Examples 18, 19, 20 and 21, all materials for component A are weighed into suitable containers and mixed thoroughly using an air motor and agitator paddle. For examples 22 and 23, all materials for component A are weighed and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to half the total weight of the mixture components. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 3.0 hours. For Examples 18, 19, 20, 21 and 23, all materials for component B except Silquest A-187 are weighed and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials with each component are capped and then placed in the Lau Dispersing Unit for a 3 hour dispersion time. After 3.0 hours of dispersion time for component B in Examples 18 and 19, additional medium is added to each vessel, approximately equal to the total weight of the mixture components. The vials are capped and then placed in the Lau Dispersing Unit for an additional 1 hour dispersing time. All final dispersions have a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix each final component B mixture thoroughly. For Example 22, all materials for component B, except Silquest A-187, OK-412 silica, and acetone, were weighed and placed in a glass jar. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vessel is closed with a lid and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. After about 3.0 hours. dispersing time, add OK-412 and acetone to the vessel, and place back in the Lau Dispersing Unit for about 5 minutes. The epoxysilane Silquest A-187 is then added to the component B mixtures after the pigment dispersion process is complete. Then mix thoroughly each final component B blend.

Prior to coating, the respective ratios of each total component A, total component B and total component C shown in Table 12 were compounded together, mixed thoroughly, and an induction period was set between 30 and 60 minutes prior to application. The first coatings of Examples 18-23 were applied by spraying onto panels of an uncoated 2024T3 aluminum alloy substrate to a dry film thickness of between 0.7 and 1.3 mils using an air blast gun. Prior to coating, the aluminum alloy panels were treated in the same manner as described for Examples 1-4. After the first coating in each example, the coated panels were stored at ambient conditions for 12 to 24 hours prior to the second coating of each example.

Second Coating: For Examples 18-23, the respective amounts of Component C materials shown in Table 12 for each example were added to appropriately sized containers and mixed thoroughly using an air motor and stirring paddle. For Examples 18, 19, 20, 21, and 23, the respective amounts of Component A and Component B shown in Table 12 for each example are added to appropriately sized containers and mixed thoroughly using an air motor and stirring paddle. The corresponding amount of Component C shown in Table 12 for each example (18, 19, 20, 21 and 23) was then added to the respectively blended A and B components for each example to obtain each final blended second coating of the example. For example 22, all materials for component A are weighed and placed in a glass jar. Then the dispersion medium is added to the vessel in an amount approximately equal to twice the total mass of the mixture components. The vessel is closed with a lid and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. In Example 22 for component B, all materials are weighed into a suitable container and mixed thoroughly using an air motor and a stirring paddle. The total A, B and C components shown in Table 12 for Example 22 are then added to an appropriately sized container and mixed thoroughly using an air motor and stirring paddle to form a final mixed second coat of Example.

After thoroughly mixing the second coatings for Examples 18-23, they are sprayed onto panels precoated with the first coatings for Examples 18-23 such that every second coating of the example is applied to the corresponding first coating of the example (i.e., the second coating of Example 20 applied over the first coat of example 20). Dry film thickness for second coats ranges from approximately 1.5 mils to 2.5 mils. The application of every second coat is carried out between the 10th and 60th minutes after the initial mixing of every final second coat.

Test panels fully covered with the coating of Examples 18-23 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The scores in Table 13 were obtained after 1176 hours of exposure for Examples 18, 19, 20, 21 and 23; and 1104 hours. for example 22. Panels are scored according to the same scale used for examples 1-4.

Table 13. Results of corrosion tests for examples 18 - 23

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size 18 First coating - 1.2% lithium in the form of lithium orthosilicate
Second coating - PU + Azole (Hybricor) 20 85 3 0 <1.25 mm nineteen First coating - 1.2% lithium in the form of lithium orthosilicate
Second coating - PU AP + Azole (Hybricor) five 70 2 0 <1.25 mm 20 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coat PU + azole (Hybricor) 25 90 4 0 <1.25 mm 21 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU AP + azole (Hybricor) five 70 3 0 <1.25 mm 22 First coating - 60% MgO without lithium
Second coating - PU + 1.2% lithium in the form of lithium orthosilicate + Azole (Hybricor) five 70 1 0 <1.25 mm 23 First coating - 35% MgO without lithium silicate
Second coating - PU AP + Azole (Hybricor) ten 70 five 0 <1.25 mm

The corrosion data in Table 13 clearly shows that the multilayer coatings in all six examples provide good corrosion resistance when the first coating as well as the second coating contains at least one corrosion inhibitor selected from a lithium compound, magnesium oxide, and an azole. Proof of good corrosion resistance is minimal blistering around the edges of the lettering and, in some cases, a minimum of corrosion products in the lettering.

Table 14. Multi-layer coating (first inhibitor coating + second inhibitor coating) - various azoles and lithium sources

Material Examples 24-
27 Example
28 Material Example 24 Example 25 Example 26 Example 27 Example 28 First coating Second cover Component A r r Component A r r r r ml Ancamide 2569 20.8 20.8 Ancamine 2432 13.8 13.8 CA9311 /
F36173 70.2 70.2 70.2 70.2 75.0 Ancamine K-54 1.3 1.3 Total 70.2 70.2 70.2 70.2 75.0 n-butyl alcohol 29.3 29.3 Xylene 6,3 6,3 Component B r r r r ml Total 71.5 71.5 CA9300 19.3 19.3 19.3 19.3 25.0 Component B r r Total 19.3 19.3 19.3 19.3 25.0 Epon 828 65.8 65.8 Xylene 3.4 3.4 Component C r r r r ml Oxsol 100 38.3 38.3 Acetone 10.0 10.0 10.0 10.0 10.0 Silquest A-187 1.6 1.6 Hybricor 204 9.0 (g) Ti-Pure R-706-11 60.0 58.0 Mercaptobenzo-thiazole 2.2 nano magnesium oxide 10.0 10.0 Dimercaptotia-diazole 2.2 Lithium Orthosilicate 5.0 Benzotriazole 2.2 Lithium carbonate 7.0 Sodium mercaptobenzo-thiazole 2.2 CA1800X 23.8 23.8 Total 12.2 12.2 12.2 12.2 ~ 19 Total 207.9 207.9 Total mass of mixture 279.4 279.4 total weight
mixes 101.7 101.7 101.7 101.7 ~ 119

The coatings of examples 24 to 28 were prepared as follows:

First Coating: For Examples 24-28, all materials for component A are weighed into suitable containers and mixed thoroughly using an air motor and agitator paddle. All materials for component B, except for Silquest A-187, are weighed and placed in glass jars. Then, a dispersion medium is added to each vessel in an amount approximately equal to twice the total weight of the components of the mixture. The vials are capped and then placed in the Lau Dispersing Unit for a dispersing time of 3 hours. All dispersions had a Hegman fineness greater than 7. Silquest A-187 epoxysilane is added to the component B blends after the pigment dispersion process is complete. Then mix thoroughly each final component B blend.

Prior to coating, the respective ratios of each total component A to total component B and total component C shown in Table 14 were compounded together, mixed thoroughly, and an induction period was set between 30 and 60 minutes prior to application. The first coatings in Examples 24 to 28 were sprayed onto panels of 2024T3 aluminum alloy substrate to a dry film thickness of between 0.5 and 1.3 mils using an air blast gun. Prior to coating, the aluminum alloy backing panels were treated in the same manner as described for Examples 1 to 4. After the first coating in each example, the coated panels were stored at ambient conditions for 12 to 24 hours prior to the second coating of each example. ...

Second Coating: For Examples 24-28, the respective amounts of Component C materials shown in Table 12 for each example were added to appropriately sized containers and mixed thoroughly using an air motor and stirring paddle. Prior to each second coating, the respective total amounts shown in Table 14 for each component A, component B, and component C of each second coating of the example are then placed in appropriately sized containers and then thoroughly mixed using an air motor and stirring paddle to obtain each final mixed second coating of the example.

After thoroughly mixing the second coatings for Examples 24-28, they are sprayed onto panels precoated with the first coatings for Examples 24-28, such that every second coating of the example is applied to the corresponding first coating of the example (i.e., the second coating of Example 24 applied over the first coat of example 24). Dry film thickness for second coats ranges from approximately 1.5 mils to 2.5 mils. Every second coat application is carried out between 10th and 60th minutes after the initial mixing of every final second coat.

Test panels fully coated with the coating of Examples 24-28 are aged at ambient conditions for a minimum of 7 days, after which a 10 cm by 10 cm “X” is drawn on the surface of the panel, which is deep enough to penetrate any surface coating and expose the underlying metal. The inscribed coated test panels are then placed in a spray chamber with a neutral salt solution - 5% sodium chloride per ASTM B117 (exception: weekly monitoring of pH value and salt concentration as opposed to daily).

The estimates in Table 15 were obtained after 1152 hours. impact. The panels are scored according to the same scale used for Examples 1-4.

Table 15. Results of corrosion tests for examples 24 - 28

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size 24 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coat PU AP + Azole (MBT) five 40 0 0 0 25 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU AP + Azole (DMTD) five 50 0 0 0 26 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU AP + Azole (BZT) ten 50 0 0 0 27 First coating - 1.2% lithium as lithium orthosilicate + 10% MgO
Second coating - PU AP + azole (NaMBT) five thirty 0 0 0 28 First coating - 1.3% lithium as lithium carbonate + 10% MgO
Second coating - PU AP + Azole (Hybricor) ten thirty 0 0 0

The corrosion data in Table 15 clearly show that the multi-layer coatings in all five examples provide good corrosion resistance when the first coating as well as the second coating contains at least one corrosion inhibitor selected from a lithium compound, magnesium oxide, and an azole. Proof of good corrosion resistance is the absence of blistering at the edges of the lettering and a minimum of corrosion products in the lettering.

Table 16. Basic Corrosion Resistance Comparison (Overview)

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size Comp. 1 One coating: no inhibitor 25 95 > 30 0 > 1.25 mm 2 One coating: 1.2% lithium (as silicate) 15 80 0 0 0

Добавление силиката лития в единственное покрытие значительно улучшает сопротивление коррозии.

The addition of lithium silicate to a single coating significantly improves corrosion resistance. 15 First coating - 1.2% lithium (as silicate)
Second coating - PU AP - without inhibitor 25 85 4 0 <1.25 mm

When a second coating is applied over the first lithium inhibitor coating, a multilayer coating is obtained, also with improved corrosion resistance relative to a single coating without inhibitor.

However, topcoating without an inhibitor will somewhat reduce the corrosion inhibiting effect of the first (i.e., single) coating. nineteen First coat -1.2% lithium (as silicate)
Second coating - PU AP + Azole (Hybricor) five 70 2 0 <1.25 mm

By introducing an azole inhibitor into the second coating (applied over the first coating with a lithium inhibitor), the decrease in the corrosion inhibiting effect is overcome, which is observed when the second coating without inhibitor is applied on top of the first coating.

Table 17: Basic Corrosion Resistance Comparison (Overview)

Example No. Description Corrosion lettering Gloss lettering Bulge lettering External swelling Maximum lettering bulge size Comp. 1 Sole Coating: Inhibitor Free 25 95 > 30 0 > 1.25 mm 8 1.2% lithium (as silicate) and 10% MgO five 80 0 0 0

Добавление MgO и силиката лития в единственное покрытие значительно повышает сопротивление коррозии.

The addition of MgO and lithium silicate to a single coating significantly improves corrosion resistance. 17 First coat -1.2% lithium (as silicate) and 10% MgO
Second coating - PU AP - without inhibitor 25 85 five 0 <1.25 mm

By applying a second coating without inhibitor over the first coating with MgO and lithium inhibitor, a multilayer coating is obtained, also with improved corrosion resistance relative to a single coating without inhibitor.

However, topcoating without an inhibitor will somewhat reduce the corrosion inhibiting effect of the first (i.e., single) coating. 21 First coating - 1.2% lithium (as silicate) + 10% MgO
Second coating - PU AP + azole (Hybricor) five 70 3 0 <1.25 mm

By introducing an azole inhibitor into the second coating (applied over the first coating with MgO and lithium inhibitor), the decrease in the corrosion inhibiting effect is overcome, which is observed when the second coating is applied without inhibitor on top of the first coating.

According to the invention, the addition of inhibitors to the coating provides improved corrosion resistance compared to the same coatings without an inhibitor, regardless of whether the coating is used as a single layer or a second coating is applied over the first layer. However, applying a topcoat without an inhibitor over the first layer containing the corrosion inhibitors of the invention results in some reduction in corrosion inhibition. The incorporation of a corrosion inhibitor into both layers (first coat and second coat) of the multilayer coating system provides corrosion resistance similar to that of a single layer with an inhibitor.

Claims (31)

1. A curable film-forming composition containing: (1) a curable organic film-forming binder component; and (2) a corrosion inhibiting component containing lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5% by weight of lithium, based on the total weight of solid resins in the curable film-forming composition. 2. The composition according to claim 1, in which the organic film-forming binder component (1) contains (a) a resin component containing epoxy functional groups; and (b) an amine functional curing agent component. 3. A composition according to claim 1, wherein the lithium silicate comprises lithium orthosilicate and / or lithium metasilicate. 4. A composition according to claim 1, wherein the corrosion inhibiting component (2) further comprises magnesium oxide and / or azole. 5. A metal substrate at least partially coated with a curable film-forming composition that contains: (1) a curable organic film-forming binder component; and (2) a corrosion inhibiting component containing lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5% by weight of lithium, based on the total weight of solid resins in the curable film-forming composition. 6. The coated metal substrate of claim 5, wherein the curable film-forming composition is applied directly to the metal substrate and there is no intermediate coating between the substrate and the curable film-forming composition. 7. The coated metal substrate of claim 5, wherein the metal substrate comprises aluminum. 8. The coated metal substrate according to claim 5, wherein the metal substrate is part of an aircraft. 9. The coated metal substrate of claim 5 further comprising an additional coating layer applied over at least a portion of the curable film-forming composition. 10. The coated metal substrate of claim 9, wherein the additional coating layer comprises a fluoropolymer and / or a polyurethane polymer. 11. The coated metal substrate of claim 9, wherein the curable film-forming composition is a base coat and the additional coat layer is a top coat composition. 12. The coated metal substrate of claim 9, wherein the curable film-forming composition is a colored undercoat layer and the overcoat layer is a transparent colorless layer composition. 13. The coated metal substrate of claim 9, wherein the additional coating layer comprises a corrosion inhibiting component comprising lithium silicate, magnesium oxide and / or azole. 14. Multilayer coated metal substrate comprising: (a) a metal substrate; (b) a curable film-forming composition applied to said metal substrate, wherein the curable film-forming composition comprises: (1) a curable organic film-forming binder component; and (2) a corrosion inhibiting component comprising lithium silicate present in the curable film-forming composition in an amount of 0.1 to 4.5 wt% lithium, based on the total weight of solid resins in the curable film-forming composition; and (c) an additional coating layer applied over at least a portion of the curable film-forming composition. 15. The coated multilayer metal substrate according to claim 14, wherein the metal substrate (a) comprises aluminum. 16. The coated multilayer metal substrate according to claim 15, wherein the metal substrate (a) is part of an aircraft. 17. A multilayer coated metal substrate according to claim 14, wherein the curable film-forming composition (b) is applied directly to the metal substrate and there is no intermediate coating between the substrate and the curable film-forming composition. 18. The coated multilayer metal substrate according to claim. 14, in which the organic film-forming component (1) contains (i) a resin component containing epoxy functional groups; and (ii) an amine functional curing agent component. 19. The coated multilayer metal substrate of claim 14, wherein the lithium silicate comprises lithium orthosilicate and / or lithium metasilicate. 20. The coated multilayer metal substrate according to claim 14, wherein the corrosion inhibiting component (2) further comprises magnesium oxide and / or azole. 21. A coated multilayer metal substrate according to claim 14, wherein the additional coating layer (c) comprises a corrosion inhibiting component comprising lithium silicate, magnesium oxide and / or azole. 22. A coated multilayer metal substrate according to claim 14, wherein the additional coating layer (c) comprises a fluoropolymer and / or a polyurethane polymer.