HK1180705B - One-component, ambient curable waterborne coating compositions, related methods and coated substrates - Google Patents

Description

One-part, ambient curable waterborne coating compositions, related methods and coated substrates

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application 61/309,652 filed on 3/2/2010, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to coating compositions. More particularly, the present invention relates to one-part, ambient curable, waterborne coating compositions. The invention also relates to methods of preparing these coating compositions, substrates coated with coatings deposited from these compositions, and methods of depositing coatings on substrates.

Background

From the standpoint of convenience for the end user, for example, in many cases it is desirable to have a coating composition in which all of the components are stored together in a single container. The properties that these coating compositions should exhibit include storage stability. In other words, the viscosity of the composition should not increase significantly over time from the standpoint that the combination is no longer suitable for convenient use in depositing a coating.

In many cases, it is desirable to use liquid coating compositions that are aqueous, rather than organic solvent-based. This desire stems primarily from environmental concerns regarding the release of Volatile Organic Compounds (VOCs) during the coating process.

It is also often desirable to provide coating compositions that are curable under ambient conditions of atmospheric temperature and pressure. These compositions are in many cases preferred to be, for example, thermally or radiation curable coating compositions because (i) little or no energy is required to cure the composition, (ii) the materials comprising some substrates cannot withstand elevated temperature curing conditions, and/or (iii) the coated large or complex articles may not be conveniently handled by thermal or radiation curing equipment.

Carbodiimide compounds are known to react with carboxyl groups under ambient conditions. As a result, this chemistry has been used to crosslink carboxyl functional resins in coating compositions. However, these compositions are not sufficiently storage stable for widespread use as one-component compositions because of the reactivity of the carbodiimide groups and the carboxyl groups.

As a result, it would be desirable to provide one-component, aqueous, environmentally curable coating compositions based on carbodiimide-carboxyl chemistry, wherein these compositions exhibit significantly improved storage stability compared to the prior art.

Disclosure of Invention

In certain aspects, the present invention relates to one-part waterborne coating compositions. The coating composition includes (a) a polycarbodiimide that is (i) hydrophilically modified; and (ii) derived from tetramethylxylylene diisocyanate; (b) a carboxylic acid functional polymer; and (c) a base in an amount greater than the theoretical amount required to neutralize 100% of the acid groups of the carboxylic acid functional polymer and sufficient to provide the composition with a pH of at least 9.0.

The invention also particularly relates to methods of making and using these coating compositions and substrates at least partially coated with coatings deposited from these compositions.

Detailed Description

For the purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including 1 and 10) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. Further, in this application, the use of "or" means "and/or" unless specifically stated otherwise, but in some cases "and/or" is also expressly used.

As noted above, certain embodiments of the present invention are directed to coating compositions, such as one-part, aqueous, ambient curable coating compositions. The term "one-component" as used herein refers to a coating composition in which all composition components are stored together in a single container and which is storage stable, meaning that the viscosity of the composition does not increase significantly over time to such an extent that the composition is no longer suitable for convenient deposition of a coating. Indeed, in certain embodiments, the one-part coating compositions of the present invention exhibit a shelf life (pot life) of 3 months or more when stored at temperatures of 120 ° F or 160 ° F, as evidenced by the lack of gelation of the composition when stored in sealed containers at those temperatures. This is believed to correspond to a storage period of 3 years or more when stored in a sealed container at ambient conditions of temperature and pressure.

As used herein, "aqueous" refers to coating compositions wherein the solvent or carrier fluid used in the coating composition primarily or primarily comprises water. For example, in certain embodiments, the carrier fluid is at least 80wt% water, based on the total weight of the carrier fluid. In addition, certain of the coating compositions of the present invention are "low VOC coating compositions". As used herein, the term "low VOC composition" means that the composition contains no more than 3 pounds of volatile organic compounds per gallon of the coating composition. As used herein, the term "volatile organic compound" refers to a compound having at least one carbon atom that is released from the composition during drying and/or curing thereof. Examples of "volatile organic compounds" include, but are not limited to, alcohols, benzene, toluene, chloroform, and cyclohexane.

The term "ambient curable" as used herein means that the coating composition, after application to a substrate, is capable of curing in the presence of ambient air having a relative humidity of from 10 to 100%, e.g., from 25 to 80%, and a temperature of from-10 to 120 ℃, e.g., from 5 to 80 ℃, in some cases from 10 to 60 ℃, and in still other cases, from 15 to 40 ℃. The term "cured" as used herein refers to a coating wherein any crosslinkable component of the composition is at least partially crosslinked. In certain embodiments, the crosslink density, i.e., the degree of crosslinking, of the crosslinkable component is from 5% to 100%, such as from 35% to 85%, or, in some cases, from 50% to 85% of complete crosslinking. One skilled in the art will appreciate that the presence and extent of crosslinking, i.e., crosslink density, can be determined by various methods, such as Dynamic Mechanical Thermal Analysis (DMTA) under nitrogen using a Polymer Laboratories MKIII DMTA analyzer.

As mentioned above, the coating composition of the present invention comprises a polycarbodiimide. The term "polycarbodiimide" as used herein refers to a polymer containing two or more units having the structure-N ═ C ═ N-. As will be appreciated, polycarbodiimides may generally be formed by subjecting polyisocyanates to condensation reactions in the presence of a verified catalyst to form polycarbodiimides having terminal NCO-functionality, as will be more fully described below.

However, in the present invention, the polyisocyanate which gives the foregoing polycarbodiimide is tetramethylxylylene diisocyanate ("TMXDI"). TMXDI suitable for use in the present invention includes, for example, m-TMXDI, p-TMXDI, and mixtures thereof. These have the following structural formulae and can be prepared by the methods described in the following documents: such as us patents 3,290,350, 4,130,577 and 4,439,616.

If desired, the polyisocyanate may be an NCO-containing adduct, for example, which may be present in the presence of an active hydrogen-containing compound chain extender prior to or during the process of polycarbodiimide formation, as described below.

The active hydrogen-containing chain extender becomes a spacer (spacer) for linking polyisocyanates together or isocyanate functional polycarbodiimides together depending on when the active hydrogen compound is added. For example, the chain extender may be added before, during, or after the formation of the polycarbodiimide having capped NCO functionality.

If a chain extender is used, any suitable compound containing active hydrogen may be used as the chain extender. The term "active hydrogen atom" refers to hydrogens which, because of their position in the molecule, exhibit activity according to the Zerewitinoff test. Thus, active hydrogens include hydrogen atoms attached to oxygen, nitrogen, or sulfur, and thus useful compounds would include those having at least two hydroxyl, thiol, primary amine, and/or secondary amine groups (in any combination). In certain embodiments, the active hydrogen-containing chain extender contains from 2 to 4 active hydrogens per molecule.

Examples of such compounds include amines including polyamines, aminoalcohols, mercapto-terminated derivatives, and alcohols (polyols) including polyhydroxy materials. Suitable polyhydroxy materials, i.e., polyols, include low or high molecular weight materials and, in some instances, have average hydroxyl numbers below 2000 as determined in accordance with ASTM method E-222-67, method B, e.g., in the range of less than 2000 to 10. The term "polyol" is meant to include materials having 2 or more hydroxyl groups per molecule.

Suitable polyols include low molecular weight diols, triols and higher alcohols, low molecular weight amide-containing polyols, and higher polymer polyols, such as polyester polyols, polyether polyols, polycarbonate polyols and hydroxyl-containing (meth) acrylic polymers. These polymers often have hydroxyl numbers of 10 to 180.

The low molecular weight diols, triols and higher alcohols useful in the present invention often have hydroxyl numbers of 200 or higher, for example in the range of 200 to 2000. These materials include aliphatic polyols, including alkylene polyols containing 2 to 18 carbon atoms. Examples include ethylene glycol, 1, 4-butanediol, 1, 6-hexanediol; alicyclic polyols such as 1, 2-cyclohexanediol and cyclohexanedimethanol. Examples of the triols and higher alcohols include trimethylolpropane, glycerol and pentaerythritol. Also useful are polyols containing ether linkages, such as diethylene glycol and triethylene glycol, and oxyalkylated glycerols, and longer chain diols such as dimer diol or hydroxy ethyl dimer.

In certain embodiments of the present invention, the chain extender comprises an organosilicone diol, which refers to a diol comprising a polysiloxane structure comprising alternating silicon and oxygen atoms. Specific examples of these chain extenders include, but are not limited to, KF 6001 (manufactured by Shin-Etsu chemical Co., Ltd.), DMS-C15 (manufactured by Gelest Inc.), and Z-6018 from Dow Corning.

As noted above, to make the polycarbodiimide used in the composition of the present invention, the isocyanate-terminated polycarbodiimide is first formed by subjecting TMXDI, which may or may not have been previously chain extended by reaction of TMXDI with an active hydrogen-containing chain extender of the type described previously, to a condensation reaction. TMXDI is condensed by elimination of carbon dioxide to form an isocyanate-terminated polycarbodiimide.

The condensation reaction is generally carried out by the following steps: a solution of the polyisocyanate is taken and heated in the presence of a suitable catalyst. This reaction is described, for example, in Angew. chem. int. Ed. Engl. of K.Wagner et al, vol.20, p.819-830 (1981). Representative examples of suitable catalysts are described, for example, in U.S. patents 2,941,988, 3,862,989, and 3,896,251. Specific examples include 1-ethyl-3-diethylphosphonothiocholine (phospholine), 1-ethyl-3-methyl-3-diethylphosphonothiocholine-1-oxide, 1-ethyl-3-methyl-3-diethylphosphonothiocholine-1-sulfide, 1-ethyl-3-methyl-phospholidine (phospholidine), 1-methylcyclophospholene-1-oxide, 1-ethyl-3-methyl-phospholidine-1-oxide, 3-methyl-1-phenyl-3-diethylphosphonothiocholine-1-oxide and dicyclic terpene alkyl or alkyl aryl phosphine oxide or camphene phenyl phosphine oxide.

The specific amount of catalyst used will depend to a large extent on the activity of the catalyst itself and the polyisocyanate used. A concentration range of 0.05 to 5 parts of catalyst per 100 parts of adduct is generally suitable.

The polycarbodiimide obtained has terminal isocyanate groups. In the present invention, the isocyanate terminated polycarbodiimide is then further reacted to impart hydrophilicity to the polycarbodiimide by reacting the blocked isocyanate group with an active hydrogen-containing hydrophilic compound so that it can be dispersed in water. Thus, the polycarbodiimide is "hydrophilically modified".

Suitable active hydrogen-containing hydrophilic compounds include monofunctional active hydrogen-containing hydrophilic compounds, such as any monohydroxy-functional, monothiol-functional, and/or monoamine (primary or secondary amine) -functional compound. However, in certain embodiments, the monofunctional active hydrogen-containing hydrophilic compound comprises a polyetheramine, such as an amine, typically a primary amine, having a polyether backboneTypically based on ethylene oxide or mixed ethylene oxide and propylene and having a molecular weight of greater than 500, for example at least 1000, on a number average basis. Suitable amines include those described in U.S. patent application publication 2009-0246393A1 [0037 ]]Those described in the paragraphs, the cited parts of which are incorporated by reference into the present application, have the following structures:

wherein R is C₁To C₄An alkyl group; a is 5 to 50, and b is 0 to 35, and when b is present, the molar ratio of a to b is at least 1: 1; r¹Is hydrogen or a hydrocarbyl group, and D is a divalent linking group or bond.

The reaction of polyetheramines with the NCO-containing carbodiimides is frequently carried out under the following conditions: stoichiometric equivalents of amine to NCO equivalents, or a slight excess of amine, and temperatures typically in the range of 80 to 110 ℃, until infrared spectroscopy of the reaction mixture indicates essentially no residual NCO functionality. The examples of the present application are illustrative. Suitable conditions for the synthesis of carbodiimides for use in the coating compositions of the present invention are also described in paragraphs [0043] - [0046] of U.S. patent application publication 2009-0246393A1, the cited parts of which are incorporated herein by reference.

The compositions of the present invention also comprise carboxylic acid functional polymers, for example, carboxyl group containing polyester resins, acrylic resins and/or polyurethane resins.

Suitable carboxyl-containing polyester resins can be prepared by condensation in a conventional manner, for example from an alcohol component and an acid component. The polyester resins described in this application also include so-called alkyd resins.

As the above alcohol component, those having two or more hydroxyl groups in each molecule, such as triols (including trimethylolpropane and hexanetriol), and diols (including propylene glycol, neopentyl glycol, butanediol, hexanediol, octanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 12-dodecanediol, 1, 2-cyclohexanediol, 1, 3-cyclohexanediol, 1, 4-cyclohexanediol, hydrogenated bisphenol A, caprolactone diol and dihydroxyethyl taurine, may be specifically mentioned.

The above acid components include those having two or more carboxyl groups in each molecule, such as aromatic dicarboxylic acids, e.g., phthalic acid and isophthalic acid, aliphatic dicarboxylic acids, e.g., adipic acid, azelaic acid and tetrahydrophthalic acid, and tricarboxylic acids, e.g., trimellitic acid. Further, long chain fatty acids such as stearic acid, lauric acid and the like, unsaturated acids such as oleic acid, myristic acid and the like, natural fats or oils such as castor oil, palm oil and soybean oil and modifications thereof may be mentioned. The above acid component may comprise two or more species.

Diacids and diols of fatty acids such as EMPOL 1010 aliphatic diacid (from Cognis Emery Group) may be used, or its corresponding diol may be used.

Further, as the diacid having hydroxyl group and carboxyl group in each molecule, there can be mentioned hydroxycarboxylic acids such as dimethylolpropionic acid and the like.

In the case where the resulting polyester resin has a hydroxyl group, the whole or a part thereof may be modified with an acid anhydride such as phthalic anhydride, succinic anhydride, hexahydrophthalic anhydride or trimellitic anhydride so that the resin may have a carboxyl group.

Suitable carboxyl group-containing acrylates can be obtained in a conventional manner, in particular by solution polymerization or emulsion polymerization of a carboxyl group-containing ethylenically unsaturated monomer and another ethylenically unsaturated monomer.

Exemplary carboxyl group-containing ethylenically unsaturated monomers include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, half esters thereof such as ethyl maleate, ethyl fumarate, and ethyl itaconate, mono (meth) acryloyloxyethyl succinate, mono (meth) acryloyloxyethyl phthalate, and the like, including mixtures thereof.

Exemplary other ethylenically unsaturated monomers include hydroxyl-containing ethylenically unsaturated monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate and products obtained by their reaction with lactones; amide-containing ethylenically unsaturated monomers such as acrylamide, methacrylamide, N-isopropylacrylamide, N-butylacrylamide, N-dibutylacrylamide, hydroxymethylacrylamide, methoxymethylacrylamide, and butoxymethylacrylamide, and similar (meth) acrylamides; and non-functional ethylenically unsaturated monomers such as styrene, alpha-methylstyrene, acrylates (e.g., methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate) and methacrylates (e.g., methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate), and the like, including mixtures thereof.

In order to obtain a desired resin by emulsion polymerization, specifically, an ethylenically unsaturated monomer having a carboxyl group, another ethylenically unsaturated monomer, and an emulsifier are often subjected to polymerization in water. As specific examples of the carboxyl group-containing ethylenically unsaturated monomer and other ethylenically unsaturated monomers, there may be mentioned those already mentioned above. The emulsifier is not particularly limited and may be any of those known to those skilled in the art.

Suitable carboxyl group-containing polyurethane resins can be obtained, for example, by reacting a compound having isocyanate groups at both ends and a compound having two hydroxyl groups and at least one carboxyl group.

The compound having an isocyanate group at both ends can be prepared, for example, by reacting a hydroxyl-terminated polyol and a diisocyanate compound, as will be understood by those skilled in the art. The compound having two hydroxyl groups and at least one carboxyl group is, for example, dimethylolacetic acid, dimethylolpropionic acid or dimethylolbutyric acid.

The coating composition of the present invention may comprise two or more of said carboxyl group containing resins.

The acid value of the carboxyl group-containing resin is not particularly limited, and is often 2 to 200, for example 2 to 30, or 20 to 200.

In the coating composition of the present invention, the carboxyl group-containing polymer is in the form of an aqueous dispersion or solution of a polymer neutralized with a base. The base is not particularly limited, and specifically includes organic amines such as monomethylamine, dimethylamine, trimethylamine, triethylamine, diisopropylamine, monoethanolamine, diethanolamine and dimethylethanolamine, and inorganic bases such as sodium hydroxide, potassium hydroxide and lithium hydroxide.

In the compositions of the present invention, the degree of neutralization is not critical. In the composition of the invention, the base is present in an amount greater than the theoretical amount required to neutralize 100% of the carboxylic acid groups in the polymer and sufficient to provide the composition with a pH of at least 9.0. In certain embodiments, the base is present in an amount sufficient to provide the composition with a pH greater than 9.0, e.g., at least 9.5 or at least 10.0.

In certain embodiments, the molar ratio of the total number of carboxylic acid groups in the coating composition to the total number of carbodiimide groups in the composition is from 0.05 to 5/1, for example from 0.05 to 4/1. Indeed, the present invention has unexpectedly found that when the amount of carbodiimide crosslinker in the composition is high relative to the amount of carboxylic acid groups present in the composition, coating compositions can be obtained which exhibit significantly improved storage stability. It has been found that said coating composition showing a significantly improved storage stability can be obtained in the following cases: when the molar ratio of the total number of carboxylic acid groups in the coating composition to the total number of carbodiimide groups in the composition is not greater than 2/1, for example not greater than 1.5/1, in some cases from 0.5 to 1.5/1, or in still other cases from 0.8 to 1.2/1. This is desirable because coating compositions having a higher proportion of carbodiimide crosslinker relative to carboxylic acid groups would be expected to provide coatings having superior physical properties when cured than similar coatings having a lower proportion of carbodiimide groups relative to carboxylic acid groups.

The thermosetting coating composition of the present invention may further contain a crosslinking agent, which is different from the polycarbodiimide as described above, corresponding to the functional group in the carboxyl group-containing aqueous resin composition. For example, when the carboxyl group-containing resin is hydroxyl group-containing, the auxiliary crosslinking agent may be, for example, an amino resin or a (blocked) polyisocyanate. It may comprise one species or two or more species. As specific examples of amino resins, mention may be made of alkoxylated melamine-formaldehyde or paraformaldehyde condensation products, such as condensation products derived from alkoxylated melamine-formaldehyde, for example methoxymethylolmelamine, butoxymethylolmelamine or n-butoxymethylolmelamine, and the commercial products available under the trademark Cymel 303. As specific examples of the above-mentioned (blocked) polyisocyanate compounds, there can be mentioned polyisocyanates such as trimethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate and isophorone diisocyanate, and derivatives thereof obtained by adding an active hydrogen-containing blocking agent such as an alcohol compound or an oxime compound, which is capable of dissociating the blocking agent under heating to generate an isocyanate group. The content of the auxiliary crosslinking agent is not particularly limited, and those skilled in the art can select it completely according to the functional group value of the carboxyl group-containing aqueous resin composition, the kind of the auxiliary crosslinking agent, and the like.

In certain embodiments, the resin solids are present in the coating compositions of the present invention in an amount of at least 50 weight percent, such as from 50 to 75 weight percent, based on the total weight of the coating composition.

In certain embodiments, the coating compositions of the present invention further comprise a colorant. As used herein, the term "colorant" refers to any substance that imparts color and/or other opacity and/or other visual effect to the composition. The colorant may be added to the coating in any suitable form, such as discrete particles, dispersions, solutions, and/or flakes. A single colorant or a mixture of two or more colorants may be used in the coating composition of the present invention.

Exemplary colorants include pigments, dyes and tints, such as those used in the paint industry and/or those listed in the medium Dry Color Manufacturers Association (DCMA), as well as special effect compositions. The colorant may comprise, for example, a finely divided solid powder that is insoluble but wettable under the conditions of use. The colorant may be organic or inorganic and may be agglomerated or non-agglomerated. The colorant may be incorporated into the coating by use of a grind vehicle (grind vehicle), such as an acrylic grind vehicle, the use of which is familiar to those skilled in the art.

Exemplary pigments and/or pigment compositions include, but are not limited to, carbazole dioxazine crude pigment (carbazole pigment), azo compounds, monoazo compounds, azide compounds, naphthol as (napthol as), salt types (lakes), benzimidazolone (benzimidazonone), condensates (condensation), metal complexes, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, tetrabutoxide, diketopyrrolopyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine (anthryanidine), flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments (quinophthalones), diketopyrrolopyrrole red ("DPPBO red"), titanium dioxide, carbon black, and mixtures thereof. The terms "pigment" and "colored filler" are used interchangeably.

Examples of dyes include, but are not limited to, those based on solvents and/or water, such as phthalocyanine green or blue, iron oxide, bismuth vanadate, anthraquinone, perylene, aluminum, and quinacridone.

Examples of coloring agents include, but are not limited to, pigments dispersed in an aqueous-based or water-miscible vehicle, such as AQUA-CHEM 896, commercially available from Degussa, I nc., charismacolarts and MAXITONER INDUSTRIAL COLORANTS, commercially available from Accurate Dispersions department of eastman chemical, inc.

As noted above, the colorant may be in the form of a dispersion, including but not limited to a nanoparticle dispersion. Nanoparticle dispersions can include one or more highly dispersed nanoparticle colorants and/or colorant particles that produce a desired visible color and/or opacity and/or visual effect. Nanoparticle dispersions may include colorants such as pigments or dyes having a particle size of less than 150 nanometers, such as less than 70 nanometers, or less than 30 nanometers. The nanoparticles may be prepared by comminuting the starting organic or inorganic pigments with an abrasive having a particle size of less than 0.5 mm. Examples of nanoparticle dispersions and methods for making the same are in U.S. Pat. No. 6,875,800B2, the disclosure of which is incorporated herein by reference. Nanoparticle dispersions can also be prepared by crystallization, precipitation, gas phase agglomeration, and chemical abrasion (i.e., partial dissolution). To minimize re-agglomeration of nanoparticles within the coating, resin-coated nanoparticle dispersions can be used. As used herein, "dispersion of resin-coated nanoparticles" refers to a continuous phase in which are dispersed discrete "composite particles" comprising nanoparticles and a coating resin on the nanoparticles. Examples of dispersions of resin-coated nanoparticles and methods for their preparation are in U.S. patent application publication No. 2005-0287348a1, filed 24.6.2004, U.S. provisional patent application publication No. 60/482,167, filed 24.6.24.2003, and U.S. patent application publication No. 11/337,062D, filed 20.1.2006, which are also incorporated herein by reference.

Examples of special effect compositions that may be used in the coating compositions of the present invention include pigments and/or compositions that produce appearance effects such as one or more of reflectance, pearlescence, metallic luster, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and/or discoloration. Other special effect components may provide other properties that may be perceived, such as opacity or texture. In certain embodiments, special effect components can produce a color shift such that the color of the coating changes when the coating is viewed at different angles. Examples of color effect components are set forth in U.S. Pat. No. 6,894,086, the disclosure of which is incorporated herein by reference. Other color effect components may include transparent coated mica and/or synthetic mica, coated silica, coated alumina, transparent liquid crystal pigments, liquid crystal coatings, and/or any component in which interference results from a refractive index difference within the material rather than from a refractive index difference between the surface of the material and air.

In certain embodiments, a photoactive component and/or a photochromic component that reversibly changes its color when exposed to one or more light sources may be used in the coating compositions of the present invention. The photochromic and/or photosensitive components may be activated by exposure to radiation of a specified wavelength. When the component is excited, the molecular structure changes and the changed structure exhibits a new color that is different from the original color of the component. When the exposure to radiation is removed, the photochromic and/or photosensitive component may return to the ground state, wherein the original color of the component is restored. In certain embodiments, the photochromic and/or photosensitive component can be colorless in a non-excited state and exhibit color in an excited state. Full color changes can manifest within milliseconds to minutes, such as 20 seconds to 60 seconds. Examples of photochromic and/or photosensitive components include photochromic dyes.

In certain embodiments, the photoactive component and/or photochromic component may be associated and/or at least partially linked, such as by covalent bonding, with a polymer and/or polymeric material capable of polymerizing the component. In contrast to some coatings in which the photosensitive component migrates out of the coating and crystallizes into the substrate, according to certain embodiments of the present invention, migration of the photosensitive component and/or photochromic component associated with and/or at least partially associated with the polymer and/or polymerizable component out of the coating is minimized. Examples of photoactive and/or photochromic components and methods for their preparation are given in U.S. patent application 2006-0014099A1, the disclosure of which is incorporated herein by reference.

Typically, the colorant is present in the coating composition in an amount sufficient to impart the desired visual and/or color effect. The colorant may comprise from 1 to 65 weight percent, such as from 3 to 40 weight percent or from 5 to 35 weight percent of the composition of the present invention, wherein the weight percents are based on the total weight of the composition.

The coating composition of the present invention may further comprise other optional ingredients such as organic solvents, defoamers, pigment dispersants, plasticizers, ultraviolet absorbers, antioxidants, surfactants, and the like. These optional ingredients, when present, are generally present in amounts of up to 30%, typically from 0.1 to 20% by weight, based on the total weight of the coating composition.

Examples of suitable solvents are polar, water-miscible solvents used in the preparation of polycarbodiimides, such as N-methylpyrrolidone. Additional solvents, such as N-methylpyrrolidone, and various ketones and esters, such as methyl isobutyl ketone, and butyl acetate, may be added. When present, the organic solvent is sometimes present in an amount of 5 to 25 weight percent, based on the total weight of the coating composition.

The coating compositions of the present invention can be prepared by any method known to those of ordinary skill in the art using the above components as starting materials. Suitable methods are described in the examples of the present application. In certain embodiments, the composition is prepared by combining an aqueous polycarbodiimide dispersion and an aqueous dispersion of a base neutralized carboxylic acid functional polymer, wherein the aqueous polycarbodiimide dispersion has a pH of greater than 7.0, such as at least 8.0, or in some cases at least 9.0, wherein the base is present in the aqueous dispersion of the base neutralized carboxylic acid functional polymer in an amount sufficient to theoretically neutralize about 100% (100%) of the carboxylic acid groups of the polymer. Additional base is then added to the mixture in an amount sufficient to provide the coating composition of the present invention.

The invention also relates to a method of using the above coating composition. These methods comprise applying the coating composition to the surface of a substrate or article to be coated, coalescing the composition to form a substantially continuous film and then curing the film.

The coating composition of the present invention is suitable for coating any of a variety of substrates, including human and/or animal substrates, such as cutin, fur, skin, teeth, nails, and the like, as well as plants, trees, seeds, agricultural fields such as pastures, arable land, and the like; turf covered areas, such as lawns, golf courses, sports fields, etc., and other land areas such as forests, etc.

Suitable substrates include cellulose-containing materials including paper, paperboard, cardboard, plywood and pressed fiberboard, hardwood, softwood, wood veneer, particleboard, particle board, oriented strand board, and fiberboard. The above-mentioned materials can be made entirely of wood such as pine, oak, maple, mahogany, cherry, and the like. However, in some cases, the material may comprise wood in combination with another material such as a resinous material, i.e., wood/resin composites such as phenolic composites, composites of wood fibers with thermoplastic polymers, and composites of wood reinforced with cement, fiber, or plastic veneers.

Suitable metal substrates include, but are not limited to, foils, sheets, or workpieces constructed from: cold rolled steel, stainless steel, and steel whose surface is treated with any of zinc metal, zinc compounds, and zinc alloys (including electrogalvanized steel, hot-dip galvanized steel, GALVANNEAL steel, and zinc alloy-coated steel), copper, magnesium, and alloys thereof, aluminum alloys, zinc-aluminum alloys such as GALFAN, GALVALUME, aluminum-coated steel, and aluminum alloy-coated steel substrates may also be used. Steel substrates (such as cold rolled steel or any of the above listed steel substrates) coated with a welded, zinc-rich or iron phosphide-rich organic coating are also suitable for use in the process of the present invention. Such weldable coating compositions are disclosed, for example, in U.S. Pat. Nos. 4,157,924 and 4,186,036. In addition, cold rolled steel is also suitable when pretreated with, for example, a solution selected from the group consisting of metal phosphate solutions, aqueous solutions comprising at least one group iiib or IVB metal, organophosphate solutions, organophosphonate solutions, and combinations thereof. In addition, suitable metal substrates include silver, gold, and alloys thereof.

Examples of suitable silicate substrates are glass, porcelain (porcelain) and ceramic (ceramic).

Examples of suitable polymeric substrates are polystyrene, polyamides, polyesters, polyethylene, polypropylene, melamine resins, polyacrylates, polyacrylonitrile, polyurethanes, polycarbonates, polyvinyl chloride, polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone and corresponding copolymers and block copolymers, biodegradable polymers and natural polymers such as gelatin.

Examples of suitable textile substrates are fibers, yarns, threads, knits, fabrics, nonwovens and garments consisting of: polyester, modified polyester, polyester blend fabrics, nylon, cotton blend fabrics, jute fibers, flax fibers, hemp and ramie fibers, viscose fibers, wool, silk, polyamide blend fabrics, polyacrylonitrile, triacetate, acetate, polycarbonate, polypropylene, polyvinyl chloride, polyester microfibers, and glass fiber fabrics.

Examples of suitable leather substrates are buffy leather (e.g. soft leather from sheep, goat or cow (nappa), and boxer-leather from calf or cow), suede leather (e.g. suede from sheep, goat or calf, and nubuck), split suede leather (e.g. from cow or calf skin), suede leather (buckskin) and sanded leather (nubuckskin); in addition, woollen skins and furs (for example furs with fur) are also known. The leather may be tanned by any conventional tanning method, especially vegetable, mineral, synthetic or combination tanned (e.g. chrome tanned, zirconyl tanned, aluminium tanned or semi-chrome tanned). The leather may also be retanned if desired; for retanning, any tanning agent commonly used for retanning can be used, such as mineral, vegetable or synthetic tanning agents, for example chromium, zirconyl or aluminium derivatives, quebracho, chestnut or wattle bark extracts, aromatic syntans, polyurethanes, (meth) acrylic compounds or (co) polymers of melamine, dicyandiamide and/or urea-formaldehyde resins.

In certain embodiments, the coating compositions of the present invention are particularly suitable for application to "flexible" substrates. As used herein, the term "flexible substrate" refers to a substrate that can be subjected to mechanical stress such as bending or stretching without significant irreversible change. In certain embodiments, the flexible substrate is a compressible substrate. "compressible substrate" and like terms refer to a substrate that is capable of undergoing compressive deformation and returning to substantially the same shape once compressive deformation ceases. The term "compressive deformation" and similar terms mean a mechanical stress that causes an at least temporary reduction in the volume of the substrate in at least one direction. Examples of flexible substrates include non-rigid substrates such as fiberglass woven and nonwoven fabrics, glass woven and nonwoven fabrics, polyester woven and nonwoven fabrics, Thermoplastic Polyurethane (TPU), synthetic leather, natural leather, processed synthetic leather, foams, air, liquid, and/or plasma filled polymeric bladders, polyurethane elastomers, synthetic fabrics, and natural fabrics. Examples of suitable compressible substrates include foam substrates, liquid-filled polymer balloons, air and/or gas-filled polymer balloons, and/or plasma-filled polymer balloons. As used herein, the term "foam substrate" refers to a polymeric or natural material comprising an open cell foam and/or a closed cell foam. As used herein, the term "open cell foam" means that the foam comprises a plurality of interconnected air chambers. As used herein, the term "closed cell foam" means that the foam comprises a series of discrete closed cells. Examples of foam substrates include, but are not limited to, polystyrene foams, polyvinyl acetate and/or copolymers, polyvinyl chloride and/or copolymers, poly (meth) acrylamide foams, polyvinyl chloride foams, polyurethane foams, and polyolefin foams and polyolefin blends. Polyolefin foams include, but are not limited to, polypropylene foams, polyethylene foams, and ethylene vinyl acetate ("EVA") foams. EVA foam includes flat sheets or plates, or molded EVA foam, such as midsoles (midsoles). Different types of EVA foam may have different types of surface porosity. Molded EVA may comprise a dense surface or "skin" while a flat sheet or plate may exhibit a porous surface. "textiles" may include natural and/or synthetic textiles such as fabrics, vinyl and polyurethane coated fabrics, meshes, nets, ropes, yarns, and the like, and may include, for example, canvas, cotton, polyester, KELVAR, polymer fibers, polyamides such as nylon and the like, polyesters such as polyethylene terephthalate and polybutylene terephthalate and the like, polyolefins such as polyethylene and polypropylene and the like, rayon, polyvinyl polymers such as polyacrylonitrile and the like, other fibrous materials, cellulosic materials, and the like.

The coating compositions of the present invention have a wide range of applications. For example, the flexible substrate may be incorporated into and/or form a component of athletic equipment, such as athletic shoes, balls, bags, clothing, and the like; clothing; an automotive interior component; a motorcycle component; household appliances such as decorative strips and furniture decorations; wall coatings such as wallpaper, wall drapes, etc.; floor coverings such as carpet (rug), rugner (runner), carpet tile, foot mats, vinyl and other flooring, carpet tile (carpet tile), and the like.

The coating composition of the present invention can be applied to the above-mentioned substrate by any of various methods including spraying, brushing, dipping, roll coating, and the like. However, in certain embodiments, the coating compositions of the present invention are applied by spray coating, and thus the compositions generally have a viscosity suitable for spray coating under ambient conditions.

After the coating composition of the present invention is applied to a substrate, the composition is allowed to coalesce to form a substantially continuous film on the substrate. Typically, the film thickness is from 0.01 to 20 mils (about 0.25 to 508 microns), such as from 0.01 to 5 mils (0.25 to 127 microns), or in some cases, from 0.1 to 2 mils (2.54 to 50.8 microns). The coating compositions of the present invention may be pigmented or clear, and may be used alone or in combination as a primer, basecoat, or topcoat.

The coating composition of the present invention is curable under the following conditions: in the presence of ambient air (which air has a relative humidity of 10 to 100%, e.g., 25 to 80%) and a temperature of-10 to 120 ℃, e.g., 5 to 80 ℃, in some cases 10 to 60 ℃, and in still other cases 15 to 40 ℃; and can be cured in a relatively short time to provide a film with good early properties that allows for handling of the coated object without adversely affecting the appearance of the film, and will ultimately cure to a film exhibiting excellent hardness, solvent resistance, and impact resistance.

The following examples illustrate the invention and are not to be construed as limiting the invention to their details. In the examples and throughout the specification, all parts and percentages are by weight unless otherwise indicated.

Example 1

The aqueous polycarbodiimide dispersions were prepared using the procedure described below and the ingredients and amounts listed in table 1.

TABLE 1

¹Methylene-bis- (4-cyclohexyl diisocyanate) from Bayer materials science, LLC.

²Polyetheramines from huntsman (EO/PO molar ratio =6.3, MW =1000)

³Anionic surfactant from Rhodia

Charge #1 was added to a 2 liter 4-neck flask fitted with a motor-driven stainless steel stirring blade, a water-cooled condenser, a nitrogen inlet, and a heating mantle (where a thermometer was connected through a temperature feedback control device). The contents of the flask were heated to 160 ℃ and held at this temperature until the isocyanate equivalent weight, measured by titration, was greater than 450 eq/g. The temperature was then reduced to 95 ℃ and charge #2 was added. Charge #3 was added over 10 minutes and charge #4 over 30 minutes while maintaining the reaction temperature at 90-100 ℃. The resulting mixture was held until the NCO equivalent stopped at about 1727 eq/g. Charge #5 was added and the mixture was held at 90-100 ℃ until the IR spectrum showed no characteristic bands for NCO. The methyl isobutyl ketone was stripped under vacuum. The batch was cooled to 80-90 ℃, and charge #6 after preheating to 85-90 ℃ was added to the reaction flask over 20 minutes while maintaining the temperature below 90 ℃. Samples of the polycarbodiimide dispersions were placed in a 120 ° F heating chamber for 4 weeks and the resin was allowed to remain dispersed.

Example 2

The following procedure and the ingredients and amounts listed in table 2 were used to prepare aqueous polycarbodiimide dispersions.

TABLE 2

¹M-tetramethylxylene diisocyanate available from Cytec Industries Inc.

²Polyetheramines from Huntsman (EO/PO molar ratio =6.3, MW =1000)

⁴Anionic surfactant from Rhodia

Charge #1 was added to a 2 liter 4-neck flask fitted with a motor-driven stainless steel stirring blade, a water-cooled condenser, a nitrogen inlet, and a heating mantle (where a thermometer was connected through a temperature feedback control device). The contents of the flask were heated to 160 ℃ and held at this temperature until the isocyanate equivalent weight, measured by titration, was greater than 450 eq/g. The temperature was then reduced to 95 ℃ and charge #2 was added. Charge #3 was added over 10 minutes and charge #4 over 30 minutes while maintaining the reaction temperature at 90-100 ℃. The resulting mixture was held until the NCO equivalent stopped at about 1300 eq/g. Charge #5 was added and the mixture was kept at 90-100 ℃ until the I R spectrum showed no characteristic band for NCO. The methyl isobutyl ketone was stripped under vacuum. The batch was cooled to 60-65 ℃, and after preheating to 60-65 ℃, charge #6 was added to the reaction flask over 20 minutes while maintaining the temperature below 65 ℃. Samples of the polycarbodiimide dispersions were placed in a 120 ° F heating chamber for 4 weeks and the resin was allowed to remain dispersed.

Example 3

Aqueous polyurethane dispersions were prepared using the following procedure and the ingredients and amounts listed in table 3.

TABLE 3

¹Polytetramethylene ether glycol from BASF Corp.

²Dimethylolpropionic acid from Perstorp polyols.

³Isophorone diisocyanate, from Bayer.

⁴Adipic acid hydrazide, available from Japan Fine Chem.

Charge #1 was added to a 5-liter 4-neck flask equipped with a motor-driven stainless steel stirring blade, a water-cooled condenser, a nitrogen inlet, and a heating mantle (where a thermometer was connected through a temperature feedback control device). The contents of the flask were heated to 60 ℃ and charge #2 was added through the funnel over a 10 minute period and the funnel was rinsed with charge # 3. Charge #4 was then added to the reaction mixture. The reaction was allowed to exotherm. After the exotherm subsides, the reaction mixture is heated back to 80 ℃ and held at that temperature until the isocyanate equivalent weight, as measured by titration, is greater than 1300-1500 eq/g. The temperature was then lowered to 50 ℃ and a preheated (40 ℃) charge #5 was added over 20 minutes while maintaining the reaction temperature at 50 ℃. Charge #6 was used as rinse; the resulting mixture was held at 50 ℃ for an additional 30 minutes and cooled to room temperature.

The polymer dispersions of examples 1,2 and 3 have the properties listed in table 4.

TABLE 4

Examples 4 to 6

The coating compositions were prepared using the following procedure and the ingredients and weight percentages listed in table 5.

TABLE 5

¹Polycarbodiimide crosslinker, 40% solids, carbodiimide equivalent 385 (relative to resin solids), commercially available from Nisshinbo Industries, Inc.

The polyurethane dispersion from example 3 was mixed with the selected carbodiimide dispersion with stirring. The pH of the resulting mixture was in each case about 8.5, measured using a pH-meter. For some examples, to further increase the pH to 10, 100% DMEA (dimethylethanolamine) was added dropwise while monitoring the pH. Samples at pH 8.5 and 10 were placed in a 120 ° F and 160 ° F heated chamber for accelerated stability testing. It is believed that 1 month at 120 ° F corresponds to 6 months at ambient conditions, and 1 month at 160 ° F corresponds to 1 year at ambient conditions. The mixture was periodically checked and the time to gel onset recorded. The results are shown in Table 6.

TABLE 6

By "gelling" is meant that the reaction between the carbodiimide and the polyurethane has been completed. The mixture appeared to be a clear solid gel. Hard settling is when the polyurethane settles to the bottom of the flask with liquid at the top. Both of these are unstable as coatings.

As seen in table 6, the coating composition of example 6 (using a TMXDI-based polycarbodiimide crosslinker) exhibited long term stability at 160 ° F of less than 1 month at a pH of less than 9 (8.6 in this case). It is believed that this means that the composition will exhibit a shelf life of less than 1 year. Coating compositions prepared at a pH of at least 9 (10 in these cases) using a carbodiimide not derived from TMXDI also exhibited long term stability at 160 ° F for less than 1 month. Thus, coating compositions using a TMXDI-based carbodiimide and a pH of at least 9 would be expected to exhibit a long term stability of less than 2 months at 160 ° F, as such results would indicate the sum of the effects of TMXDI and high pH, respectively, when used. However, this was not observed. An unexpected synergistic effect was observed from the use of a TMXDI based carbodiimide in combination with a pH of at least 9. This synergistic effect is shown by the result that the coating composition exhibits a long term stability at 160 ° F for more than 3 months.

We believe that this unexpected synergistic effect is statistically significant and actually meaningful. Statistically, the present invention shows long term stability at 160 ° F, which is more than 50% greater than our originally expected results. We consider this to be statistically significant. In practice, this means that our range will have a storage stability of over 3 years under ambient conditions, which makes our invention commercially viable as a one-component coating. This is because commercial requirements often dictate that one-component coatings exhibit a shelf life of at least 2 years. The comparative examples do not meet this need because, based on the results set forth in table 6, they would be expected to have a shelf life of less than 2 years.

Examples 7 to 9

The coating compositions were prepared using the following procedure and the ingredients and weight percentages listed in table 7.

TABLE 7

¹Prepared as described in us patent 7,709,093, example 1

²Polycarbodiimide crosslinker, 40% solids, carbodiimide equivalent 385 (relative to resin solids), available from Nisshinbo Industries, Inc.

The polyurethane dispersion was mixed with the selected carbodiimide dispersion with stirring. The pH of the resulting mixture was 8.3 to 8.7, as measured using a pH-meter. To further increase the pH, 50% DMEA (dimethylethanolamine) was added dropwise while monitoring the pH. Samples at pH 8.5, 9, 9.5 and 10 were placed in heating chambers at 120 ° F and 160 ° F for accelerated stability testing. It is believed that 1 month at 120 ° F corresponds to 6 months at ambient conditions, and 1 month at 160 ° F corresponds to 1 year at ambient conditions. The mixture was periodically checked and the time to gel onset recorded. The results are shown in Table 8.

TABLE 8

By "gelling" is meant that the reaction between the carbodiimide and the polyurethane has been completed. The mixture appeared to be a clear solid gel. Hard settling is when the polyurethane settles to the bottom of the flask with liquid at the top. Both of these are unstable as coatings.

Viscosity was measured after removing the samples from the heating chamber and allowing them to reach room temperature (25 ℃). Viscosity measurements were performed using a cone (50mm diameter) plate Paar Physica MCR 501 rheometer (from Anton Paar) for 10s^-1The shear rate of (2) is measured.

As seen in table 8, the coating composition of example 9 (using a TMXDI-based polycarbodiimide crosslinker) exhibited long term stability at 160 ° F for less than 40 days at a pH of less than 9.5. It is believed that this means that the composition will exhibit a shelf life of less than 1 year. Coating compositions having a pH of at least 9.5 but prepared using a carbodiimide not derived from TMXDI exhibited stability at 160 ° F for less than 24 hours. Thus, it would be expected that coating compositions using a TMXDI-based carbodiimide and a pH of at least 9.5 would also exhibit a long-term stability at 160 ° F of less than 40 days, as such results would indicate the sum of the effects of TMXDI and high pH, respectively, when used. However, this was not observed. An unexpected synergistic effect was observed from the use of a TMXDI based carbodiimide in combination with a pH of at least 9.5. This synergistic effect is shown by the result that the coating composition exhibits a long term stability at 160 ° F for more than 40 days.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention, as defined by the appended claims.

Claims (5)

1. A one-component waterborne coating composition comprising:

(a) a polycarbodiimide which is the reaction product of an isocyanate terminated polycarbodiimide derived from tetramethylxylylene diisocyanate, with a polyetheramine having a molecular weight greater than 500, the polyetheramine having the structure:

wherein R is C₁To C₄An alkyl group; a is 5 to 50, and b is 0 to 35, and the molar ratio of a to b when b is present is at least 1: 1; r¹Is hydrogen or a hydrocarbyl group, and D is a divalent linking group or bond;

(b) a carboxylic acid functional polymer; and

(c) an organic amine in an amount greater than a theoretical amount required to neutralize 100% of the acid groups of the carboxylic acid functional polymer and sufficient to provide the composition with a pH of at least 10.0.

2. The coating composition of claim 1, wherein the tetramethylxylylene diisocyanate comprises m-tetramethylxylylene diisocyanate.

3. The coating composition of claim 1, wherein the carboxylic acid functional polymer comprises a polyurethane.

4. A method of using the coating composition of claim 1, comprising:

(a) applying the coating composition to the surface of the substrate to be coated,

(b) joining the compositions to form a substantially continuous film; and

(c) the film is cured.

5. A method of preparing a coating composition comprising:

(a) combining the following (i) and (ii):

(i) the aqueous dispersion of polycarbodiimide of claim 1, wherein the aqueous dispersion has a pH of greater than 7.0, and

(ii) an aqueous dispersion of an organic amine neutralized carboxylic acid functional polymer; and

(b) adding an organic amine to the combination of step (a) in an amount sufficient to provide the combination with a pH of at least 10.0.