Self-cleaning and erosion resistant coatings and coated articles

Abstract

An aqueous coating composition includes: a (meth)acrylate polymer, a polycarbonate-containing polyurethane, a coalescent, and optionally an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative.

Description

SELF-CLEANING AND EROSION RESISTANT COATINGS AND COATED ARTICLESCROSS REFERENCE TO RELATED APPLICATIONThis application claims priority to and the benefit of U.S. Provisional Application No. 63 / 562,487, filed on March 7, 2024, the content of which is incorporated herein by reference in its entirely.BACKGROUND

[0001] This disclosure relates to coatings and coated articles. Articles such as wind turbines are often used under various weather conditions. Dust, debris and fungus can grow and accumulate on the surface of rotor blades for wind turbines and negatively affect power generation. In addition, the rotor blades may be subjected to environmental conditions that include abrasive materials, such as sand particles and / or rain droplets. The interaction of these abrasive materials with the rotor blades may cause portions of the rotor blades to erode. Accordingly, a coating having a self-cleaning effect is desired to minimize the accumulation of dirt, debris and fungus. It would be a further advantage if such a coating is erosion resistant. There remains a need for improved coatings that are self-cleaning and erosion resistant.SUMMARY

[0002] An aqueous coating composition comprises: a (meth)acrylate polymer, a polycarbonate-containing polyurethane, a coalescent, and optionally an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative.

[0003] A coated article comprises: a substrate; and a coating disposed on a surface of the substrate, wherein the coating is formed from the above-described aqueous coating composition, and wherein the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.DETAILED DESCRIPTION

[0004] The present disclosure relates to a coating and a coated article that are used in industries such as oil and gas, chemicals, energy, and transportation. In particular, the coating can have self-cleaning characteristics, thus minimizing the accumulation of dust, debris,fungus or other undesirable materials on the surface of the articles. The coating can also protect the article from damages caused by impact, erosion or wear, thus extending the operational life of the article, even when the article is used under harsh climate conditions.

[0005] The coating can be made from an aqueous coating composition comprising (i) a (meth)acrylate polymer; (ii) a polycarbonate-containing polyurethane; (iii) a coalescent; and (iv) optionally an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative.

[0006] Unless otherwise indicated, a reference to a “(meth)acrylate” polymer or compound (where “meth” is in parentheses or bracketed) is meant to include both acry late and methacrylate polymers or compounds. The term “polymer” includes both homopolymers and copolymers (i.e., polymers of two or more different monomers).

[0007] The (meth)acrylate polymer in the aqueous coating composition is a polymer of (meth)acrylate monomers, optionally together with other ethyenically unsaturated monomers. (Meth)acrylate monomers can include aliphatic or aromatic (meth)acrylate monomers. Optionally the (methy)acrylate monomers can include functional groups such as hydroxyl groups, epoxy groups, ether groups, carbonyl groups, carboxyl groups, carboxylate groups, allyl groups, ureido functional groups, or a combination thereof. Examples of the (meth)acrylate monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, glycidyl methacrylate, 4- hydroxybutyl acrylate glycidyl ether, 2-(acetoacetoxy)ethyl methacrylate (AAEM), allyl methacrylate, allyl acrylate, ureido methacrylate, ureidoacrylate, polyfunctional (meth)acrylates, for example, di-, tri- and tetra- functional acrylates such as dipropylene glycol diacrylate (DPGDA), propoxylated glyceryl triacrylate (GPTA), pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, combinations thereof, and the like.

[0008] The other ethyenically unsaturated monomers that are not (meth)acrylate monomers can include acrylic acid or salts thereof, methacrylic acid or salts thereof, vinyl acetate, vinyl propionate, acrylonitrile, styrene, a-methyl styrene, vinyl toluene, vinyl chloride, diacetone acrylamide (DAAM), acrylamide, methacrylamide, methylol (meth)acrylamide, vinyl acetate, monoolefins, conjugated dienes such as butadiene, unsaturated polyesters, or combinations thereof.

[0009] The (meth)acrylate polymer can be a self-crosslinkable (meth)acrylate copolymer. The (meth)acrylate polymer can also be a film-forming polymer.

[0010] Where the (meth)acrylate polymer is a crosslinking type, the monomers include functional or crosslinking monomers such as acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, N-(alkoxymethyl) acrylamides or N-(alkoxymethyl) methacrylamides, where the alkoxy group may be, for example, a butoxy group, glycidyl acrylate, glycidyl methacrylate, 2-(acetoacetoxy)ethyl methacrylate (AAEM), diacetone acrylamide (DAAM), or combinations thereof. When used, the (meth)acrylate polymer can include at least 0.1 weight percent (wt%), at least 0.5 wt%, at least 1 wt%, or at least 2 wt% of one or more functional or crosslinking monomers, based on the total weight of monomers used to make the (meth)acrylate polymer. The (meth)acrylate can include less than 10 wt%, less than 6 wt%, less than 5 wt%, or less than 4 wt% of one or more functional or functional monomers, based on the total weight of the monomers used to make the (meth)aciylate polymer.

[0011] In an aspect, the (meth)acrylate polymer is a copolymer formed from monomers including two or more, three or more, four or more of, or all of: methyl methacrylate, butyl acrylate, methacrylic acid (or acrylic acid), a ureido-functional monomer; and a crosslinking monomer preferably selected from diacetone acrylamide or 2- (acetoacetoxy)ethyl methacrylate. For example, the (meth)acrylate polymer can be formed from both methyl methacrylate and butyl acrylate, where the combined weight of methyl methacrylate and butyl acrylate is at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 85 wt%, or at least 90 wt%, but less than 99.9 wt% based on the total weight of the monomers used to make the (meth)acrylate.

[0012] As another example, the (meth)acrylate polymer can be formed from a monomer composition comprising an alkyl (meth)acrylate monomer, or a mixture of alkyl (meth)acrylate monomers, and optionally (meth)acrylic acid, styrene, a- methyl styrene, vinyl toluene, vinyl acetate, vinyl propionate, allyl methacrylate, or combinations thereof, lite alkyl (meth)acrylate monomer is preferably a Cus alkyl or CM alkyl (meth)acrylate monomer. The alkyl (meth)acrylate monomer, or a mixture of alkyl (meth)acrylate monomers can be present in the monomer mixture in an amount of at least 90% by weight of the monomer mixture.

[0013] The amount of the (meth)acrylate polymer in the aqueous coating composition can be 25 to 70 wt%, such as 30 to 65 wt%, 35 to 60 wt%, or 40 to 55 wt% based on a dry weight of the aqueous coating composition. Alternatively, or in addition, the (nieth)acrylate polymer can be present in the aqueous coating composition in an amount of 20 to 50 wt%, 25 to 45 wt%, or 30 to 40 wt%, based on a total weight of the aqueous coating composition.

[0014] When expressed by volume, the amount of the (meth)acrylate polymer in the aqueous coating composition can be 25 to 70 volume percent (vol%), such as 30 to 65 vol%, 35 to 60 vol%, or 40 to 55 vol% based on a dry volume of the aqueous coating composition. Alternatively, or in addition, the (metb)acrylate polymer can be present in the aqueous coating composition in an amount of 20 to 50 voi%, 25 to 45 vol%, or 30 to 40 vol%, based on a total volume of the coating composition.

[0015] The polycarbonate-containing polyurethane in the aqueous coating composition refers to a polyurethan having carbonate linkages. The carbonate linkages can have a repeating structure of formula (1)formula (1).In formula (1), each occurrence of R is independently an aliphatic group, for example a C1-30, C3-20, C4-15, or C4-12aliphatic group. Thus the polycarbonate-containing polyurethane is an aliphatic polycarbonate-containing polyurethane. In an aspect, each occurrence of R is independently a C1-30, C3-20, C4-15, C4-12, or C4-10saturated hydrocarbon. The polycarbonate- containing polyurethane can be free of isocyanate groups.

[0016] The polycarbonate-containing polyurethan can be prepared from polycarbonate polyols such as polycarbonate diols and isocyanates. The polycarbonate-containing polyurethan can also be prepared from a polycarbonate-containing polyurethane prepolymer, which is a derivative of the corresponding polycarbonate polyol in which all the hydroxyl end groups have been reacted with an isocyanate leaving isocyanate groups (NCO) at the termini instead of hydroxyls. The prepolymer can be cured by the addition of one or more polyols, in proportion to the free NCO content, to complete the polymerization reaction. Chain extenders, crosslinkers, or a combination thereof can also be used. Methods of making polycarbonate-containing polyurethanes are known and described for example in WO2011 / 129940.

[0017] Suitable isocyanates for use in preparing the polycarbonate-containing polyurethane can include a wide variety of organic mono- and polyisocyanates. Examples of monoisocyanates include benzyl isocyanate, toluene isocyanate, phenyl isocyanate and alkyl isocyanates in which the alkyl group contains from 1 to 12 carbon atoms. The polyisocyanates can include aromatic, cycloaliphatic and aliphatic isocyanates. Examples of polyisocyanates include m-phenylene diisocyanate, tolylene-2- 4-diisocyanate, tolylene-2-6- diisocyanate, isophorone diisocyanate, 1,3- and / or 1,4- bis(isocyanatomethyl)cyclohexane (including cis- or trans-isomers of either), hexamethylene- 1,6- diisocyanate, tetramethylene-1.4-diisocyanate, cyclohexane- 1,4-diisocyanate, hexahydrotolylene diisocyanate, methylene bis(cyclohexaneisocyanate) (H12MDI), naphthylene- 1,5 -diisocyanate, methoxyphenyl-2,4- diisocyanate, diphenylmethane-4,4'-diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'- dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4-4'-biphenyl diisocyanate, 3,3'- dimethyldiphenyl methane-4,4'-diisocyanate, 4,4',4"-triphenyl methane triisocyanate, a polymethylene polyphenylisocyanate (PMDI), tolylene-2,4,6-triisocyanate and 4,4'- dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate. In an aspect, the polyisocyanate is diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, PMDI, tolylene-2,4- diisocyanate, tolylene-2,6-diisocyanate or mixtures thereof. Diphenylmethane-4,4 '- diisocyanate, diphenylmethane-2,4' -diisocyanate and mixtures thereof are generically referred to as MDI, and all may be used. Tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate and mixtures thereof are generically referred to as TDI, and all may be used.

[0018] A chain extender means a material having two isocyanate-reactive groups per molecule and an equivalent weight per isocyanate -reactive group of less than 400, preferably less than 200 and especially from 31 to 125. The isocyanate reactive groups can include hydroxyl, primary aliphatic or aromatic amine or secondary aliphatic or aromatic amine groups. Examples of chain extenders include amines, ethylene glycol, 1,4-butanediol, diethylene glycol, 1 ,2-propylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane dimethanol, ethylene diamine, phenylene diamine, bis(3-chloro-4- aminophenyl)methane and2.4-diamino-3,5-diethyl toluene.

[0019] "Crosslinkers" are materials having three or more isocyanate- reactive groups per molecule and an equivalent weight per isocyanate -reactive group of less than 400. Crosslinkers may contain from 3 to 8, especially from 3 to 4 hydroxyl, primary amine or secondary amine groups per molecule and have an equivalent weight of from 30 to 200, especially from 50 to 125. Examples of suitable crosslinkers include diethanol amine, monoethanol amine, triethanol amine, mono- di- or tri(isopropanol) amine, glycerine, trimethylol propane, pentaerythritol, and the like.

[0020] The amount of the polycarbonate-containing polyurethane in the aqueous coating composition can be 25 to 70 wt% or 25 to 60 wt%, such as 35 to 60 wt%, 40 to 55 wt%, 25 to 55 wt%, 25 to 50 wt%, or 25 to 45 wt%, based on a dry weight of the aqueous coating composition. Alternatively, or in addition, the polycarbonate-containing polyurethane can be present in an amount of 20 to 50 wt%, 25 to 45 wt%, or 30 to 40 wt%, based on a total weight of the aqueous coating composition.

[0021] When expressed by volume, the amount of the polycarbonate-containing polyurethane in the aqueous coating composition can be 25 to 60 vol%, such as 25 to 55 vol%, 30 to 60 vol%, 35 to 60 vol%, 40 to 55 vol%, 25 to 50 vol%, or 25 to 45 vol%, based on a dry volume of the aqueous coating composition. Alternatively, or in addition, the polycarbonate-containing polyurethane can be present in the aqueous coating composition in an amount of 20 to 50 vol%, 25 to 45 vol%, or 30 to 40 vol%, based on a total volume of the coating composition.

[0022] In an aspect, the (meth)acrylate polymer and the polycarbonate-containing polyurethane in the aqueous coating composition have a weight ratio of 4:1 to 1 :4, 3:1 to 1:3, 2:1 to 1 :2, 2:1 to 1 :1 , or 1.5:1 to 1 :1.

[0023] In another aspect, the (meth)acrylate polymer and the polycarbonate- containing polyurethane in the aqueous coating composition have a volume ratio of 4: 1 to 1 :4, 3 : 1 to 1 :3, 2: 1 to 1 :2, 2: 1 to 1 : 1 , or 1.5 : 1 to about 1 :1.

[0024] The (meth)acrylate polymer and the polycarbonate-containing polyurethane can be present in the aqueous coating composition in a total combined weight of 65 to 97 wt%, 70 to 95 wt%, 80 to 97 wt%, 85 to 97 wt%, 70 to 90 wt%, or 80 to 90 wt%, based on a dry weight of the aqueous coating composition. The (meth)acrylate polymer and the polycarbonate-containing polyurethane can be present in the aqueous coating composition in a total combined weight of 50 to 90 wt%, 55 to 80 wt%, 60 to 80 wt%, or 65 to 75 wt%, based on a total weight of the aqueous coating composition.

[0025] The coalescent in the aqueous coating composition can assist in coalescing the (meth)acrylate polymer, the polycarbonate-containing polyurethane, or a combination thereof. In other words, the coalescent can provide good film forming properties for (meth)acrylate polymer, the polycarbonate-containing polyurethane, or a combination thereof.

[0026] The coalescent can have a structure represented by formula (2):R1— [C(O)— X— O]n— R2formula (2), wherein R1is a C1-30or C1-20 organic group, X is a single bond or a divalent C1-10organic group, R2is hydrogen or a C1-30or C1-20organic group, and n is 1 to 10.

[0027] The coalescent can be an ester alcohol where R2has a hydroxyl substituent.

[0028] In an aspect, R1is a C1-15organic group, for example a C1-10, C2-8, or C2-5alkyl, X is a single bond, R2is a C1-15, C3-10, or C5-10organic group, and n is 1. For example R2is a C1-15, C3-10, or C5-10alkyl with a hydroxyl substituent.

[0029] Examples of the coalescent can include, for example, those disclosed in U.S. Pat. No. 8,440,752. Specific examples include, for example: ester alcohols such as 2,2,4-trimethyl- 1,3 -pentanediol monoisobutyrate, alkyl phthalate esters (e.g., dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, di-2- ethylhexyl phthalate, heptyl nonyl undecyl phthalate, butyl cyclohexyl phthalate, and dicyclohexyl phthalate); aryl phthalate esters (e.g., diphenyl phthalate); alkyl aryl phthalate esters (e.g., butyl benzyl phthalate); alkyl citrate esters (e.g., tributyl citrate and triethyl citrate); isosorbide di-alkyl ethers (e.g., dimethyl and diethyl isosorbide ether); alkyl maleates (e.g., dioctyl maleate and bis(2- ethylhexyl) maleate); alkyl adipate esters (e.g., bis(2-ethylhexyl) adipate and dioctyl adipate); alkyl aryl adipate esters (e.g., benzyl octyl adipate); benzoate esters (e.g., diethylene glycol dibenzoate, isodecyl benzoate, oxtyl benzoate); azelates (e.g., bis(2- ethylhexyl)azelate); ricinoleic acid esters; polyethylene glycol ethers; tri(ethylene glycol)bis(2- ethylhexanoate); tetra( ethylene glycol)bis(2-ethylhexanoate); glyceryl monooleate; octadecenoic acid methyl ester, and oleic acid monoester of propylene glycol; and fatty acid / oil derivatives such as those available from ADM under the trade designation ARCHER RC.

[0030] Specific examples of the coalescent include bis(2-ethylhexyl) maleate, bis(2- ethylhexyl) adipate, bis(2-ethylhexyl) azelate, isodecyl benzoate, tri(ethylene glycol)bis(2- ethylhexanoate), tetra( ethylene glycol)bis(2-ethylhexanoate), tributyl citrate, octyl benzoate, di(ethylene glycol)dibenzoate, octadecenoic acid methyl ester, oleic acid monoester of propylene glycol, 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, benzoates such as alkyl benzoates, monobenozates and dibenozates, dioctyl maleate, oleic acid propylene glycol esters, and hexanoates. The coalescent can include one or a combination of two or more of the exemplified coalescent compounds.

[0031] The aqueous coating composition can include 0.5 to 15 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, 1 to 5 wt%, 1 to 15 wt%, 2 to 10 wt%, or 5 to 10 wt% of the coalescent, based on a dry weight of the aqueous coating composition. Alternatively, or in combination, the aqueous coating composition can include 0.5 to 10 wt%, 0.5 to 8 wt%, 0.5 to 5 wt%, or 1 to 5 wt% of the coalescent, based on a total weight of the aqueous coating composition.

[0032] Optionally the aqueous coating composition further comprise at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant (also referred to as a slip or anti-blocking agent), or a preservative. In an aspect, the aqueous coating composition comprises 0.5 to 15 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, 1 to 10 wt%, or 3 to 10 wt% of an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative, based on a dry weight of the aqueous coating composition. Alternatively, or in addition, the aqueous coating composition comprises 0.1 to 10 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, or 1 to 5 wt% of an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative, based on a total weight of the aqueous coating composition.

[0033] As described in US 7,923,513, a surface-active agent can modify the interaction of a coating composition with the substrate, in particular, the agent can modify the ability of the composition to wet a substrate. Surface-active agents may also include leveling, or flow agents, and the like.

[0034] Surface-active agent is known and can include polysiloxane defoamers such as a methylalkylpolysiloxane commercially available under the trade name BYK-077 or BYK- 500 from Byk Chemie, polymeric defoamers such as that commercially available under the trade name BYK 051, or other surface-active agent such as BYK-053, BYK-055, BYK-057, BYK-020, BYK-065, BYK-066N, BYK-067A, BYK-070, BYK-080A, BYK-088, BYK-141, BYK-019, BYK-021, BYK-022, BYK-023, BYK-024, BYK-025, BYK-028, BYK-011, BYK-031, BYK-032, BYK-033, BYK-034, BYK-035, BYK-036, BYK-037, BYK-038, BYK-045, BYK-A530, BYK-A555, BYK-071, BYK-060, BYK-018, BYK-044, BYK-094, BYK 333, BYK3760, or BYKUMEN, commercially available from Byk Chemie. In an aspect, the coating composition comprises two or more, for example two to six or two to five different surface-active agents.

[0035] In an aspect, the surface-active agent includes a poly oxyalkylene silicone oil as described for example in WO2023036923. As used herein, a polyoxyalkylene silicone oil refers to a silicone oil carrying polyoxyalkylene chains. The polyoxyalkylene chains can be included in the silicone oil at pendant and / or terminal positions of the silicone polymer chain.

[0036] The polyoxyalkylene chains can impart hydrophilic character to the silicone oil and include polyethylene glycol) chains, polypropylene glycol) chains and poly(ethylene glycol-co-propylene glycol) chains), preferably poly(ethylene glycol) chains. Examples of the latter are polyethylene glycol)- block-poly(propylene glycol), poly(ethylene glycol)-block- poly(propylene glycol)-block- poly(ethylene glycol), polypropylene glycol)-block- poly(ethylene glycol), polypropylene glycol)-block-poly(ethylene glycol)-block- polypropylene glycol), and polypthylene glycol- ranctom-propylene glycol). In an aspect, the polyoxyalkylene chains are poly(ethylene glycol) chains or poly(ethylene glycol-co-propylene glycol) chains wherein the weight ratio between ethylene glycol (PEG) and propylene glycol (PPG) is more than 25:75, such as in the range of 95:5 to 25:75, e.g. 90:10 to 30:70, preferably 75:25 to 35:65, more preferably 60:40 to 40:60.

[0037] The polyoxyalkylene ehams can include at least 3 repeating units, such as at least 5 repeating units. For example, the polyoxyalkylene chains can include 3*200 repeatingunits, such as 3-150, or 5-100, or 5-80 repeating units. In another aspect the polyoxyalkylene chains include 3-30 repeating units, such as 3-20 repeating units, such as 3 to 15 or even 4 to 12 repeating units. In yet another aspect the poly oxy alkylene chains include 6 to 20 repeating units, such as 8 to 15 repeating units.

[0038] The polyoxyalkyiene chains can have a number average molecular weight (Mn) in the range of 100-20,000 g / mol, such as in the range of 100-15,000 g / niol, hr particular in the range of 200-10,000 g / mol, or in the range of 200-8,000 g / mol.

[0039] The silicone oil has repeating units of -Si(Rl)(R2)- wherein R1 and R2 are each independently a Ct-? alkyl or an aryl (e.g. phenyl (-C5H5)), in particular methyl.

[0040] The relative weight of the polyoxyalkyiene chains in the polyoxyalkyiene silicone oils can be 1% or more of the total weight (e.g. 1-90%), such as 5% or more (e.g. 5- 80%), in particular 10% or more (e.g. 10-70%) of the total weight of the polyoxyalkyiene silicone oil. In an aspect, the relative weight of the polyoxyalkyiene chains is in the range of 25-60 % such as 30-50 % of the total weight of the polyoxyalkyiene silicone oil.

[0041] The surface-active agent which comprises polyoxyalkyiene silicone oils can be included in the aqueous coating composition in an amount of 0.1 to 5 wt%, 0.2 to 3 wt%, or 0.5 to 2.5 wt%, based on a dry weight of the aqueous coating composition, or based on a total weight of the aqueous coating composition.

[0042] The rheology modifier can be an organic rheology control agent. In an aspect, the rheology modifier can include a hydrophobically modified ethylene oxide urethane rheology modifier (HEUR). HEURs are known and described for example in US 2023 / 0365833. HEURs are nonionic branched or unbranched block copolymers of polyethylene oxide chains, polypropylene oxide chains or (polyethylene oxide-propylene oxide) chains, which are linked to one another via urethane bonds and which carry terminal long-chain alkyl or alkenyl groups having 8 to 30, preferably 10 to 24 and more preferably 12 to 20 carbon atoms or aryl groups or alkylated aryl groups having 6 to 30, preferably 6 to 20 carbon atoms. The alkyl groups are for example dodecyl or stearyl groups; an example of a typical alkenyl group is an oleyl group; an example of the aryl group is the phenyl group; and an example of an alkylated aryl group is a nonylphenyl group. The rheological modifier can be present in an amount of 0.05 to 5 wt%, 0.1 to 5 wt%, or 0.5 to 4 wt%, based on a dry weight of the aqueous coating composition. Alternatively, or in addition, the rheological modifier can be present in an amount of 0.01 to 5 wt%, 0.05 to 3 wt%, or 0.05 to 2 wt%, based on a total weight of the aqueous coating composition.

[0043] The aqueous coating composition can comprise surfactants or dispersants suchas anionic, amphoteric and nonionic materials, In an aspect, the surfactant is an acetylene glycol surfactant. Examples of the acetylene glycol surfactant include SURFYNOL 104, SURFYNOL 104E, SURFYNOL 10411, SURFYNOL 104 A, SURFYNOL 104BC, SURFYNOL 104DPM, SURFYNOL 104PA, SURFYNOL 104PG-50, SURFYNOL 1041.,, SURFYNOL 420, SURFYNOL 440, SURFYNOL 465, SURFYNOL 485, SURFYNOL 2520 , SURFYNOL SE, SURFYNOL SE-F, SURFYNOL 504, SURFYNOL 61, SURFYNOL DF37, SURFYNOL DF110D, SURFYNOL CT111, SURFYNOL CT121, SURFYNOL CT1 31, SURFYNOL CT 136, SURFYNOL TG and SURFYNOL GA (hereinbefore, all are trade names, manufactured by Air Products and Chemicals, Inc.), OLFINE B, OLFINE Y, OLFINE P, OLFINE A, OLFINE STG, OLFINE SFC, OLFINE El 004, OLFINE El 006, OLFINE El 008, OLFINE E1010, OLFINE PD-001 , OLFINE PD-002W, OLFINE PD-003, OLFINE PD-004, OLFINE EXP, 4001 , OLFINE EXP. 4036, OLFINE EXP, 4051, OLFINE AF-103, OLFINE AF-104, OLFINE AK-02, OLFINE SK-14 and OLFINE AE-3 (hereinbefore, all are trade names, manufactured by Nissin Chemical Co., Ltd.), ACETYLENOL E00, ACETYLENOL E00P, ACETYLENOL E40, ACETYLENOL El 00 (hereinbefore, all are trade names, manufactured by Kawaken Fine Chemicals Co., Ltd,), and the like.

[0044] In the case where the coating composition contains the surfactant, a content thereof can be 0.01 to 5 wt%, 0.05% to 2 wt%, or 0,1 to 2 wt%, based on a dry weight of the coating composition, or based on a total weight of the aqueous coating composition.

[0045] The coating composition can also comprise a lubricant such as a fluorinebased or silicone-based lubricant. The use of a silicone-based lubricant is particularly preferable. Specific examples of silicone-based lubricants include polydimethylsiloxane, polyether-modified polydimethylsiloxane and polymethylalkylsiloxane. A lubricant containing a fluorine compound or silicone compound having an aryl group or aralkyl group may also be used. In addition, a lubricant containing a fluorine compound or silicone compound having a crosslinking reactive group (reactive lubricant) may also be used. In the case where the coating composition contains the lubricant, a content thereof can be 0.1 to 5 wt%, 0.5% to 3 wt%, based on a dry weight of the aqueous coating composition, or based on a total weigh of the aqueous coating composition.

[0046] Ultraviolet-light (UV) absorbers, heat stabilizers, colorants, fungicides, or a combination thereof can also be included in the aqueous coating composition.

[0047] The light stabilizer can include a hindered amine light stabilizer (HALS). HALS is commercially available, for example, under the trade name BLS 292 from Mayzo, TINUVIN 123 or UVINUL 4092 from BASF Corp., OMNISTAB LS292 from ICG SpecialtyChemicals, OMNISTAB LS944 from ICG Specialty Chemicals, SABOSTAB 119 or SABOSTAB 94 from Sabo S.p.A., or LOWILITE from Addivant. If present, the light stabilizer can be used in an amount of 0.01 to 5 weight percent based on a dry weight of the aqueous coating composition. The aqueous coating composition can comprise more than one light stabilizer if needed.

[0048] The UV absorber that can be useful with the aqueous coating composition include avobenzone, 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene (Benetex OB+), disodium 4,4'-bis(2-sulfonatostyryl)biphenyl (Benetex OB-M1), benzenepropanoic acid (BLS 99-2), 2,3,6,7-tetrahydro-9-methyl-lH,5H-quinolizino(9,l-gh)coumarin (Coumarin 102), Martins Yellow, morin hydrate, nitrofurazone, 2-nitrophenyl phenyl sulfide (NPS), 5,12- naphthacenequinone (NTAQ), octocrylene, phenazine, l,4-bis-(2-(5-phenyloxazolyl))- benzene (POPOP), Quinoline Yellow, 3,3',4',5,6-pentahydroxyflavone (Quercetin), salicylaldehyde, Sudan I, triamterene, UV386A, or 9,10-diethoxyanthracene (UVS-1101). Other known UV absorbers can also be used. UV absorbers can be used in an amount of 0.05 to 10 weight percent based on a dry weight of the aqueous coating composition. The coating composition can comprise more than one UV absorber.

[0049] The preservative can include a preservative (e.g., biocides, fungicides, algaecides, and the like) selected from among formaldehyde and formaldehyde-releasing compounds, isothiazolinones such as N-octylisothiazolone, 4,5-dichloroisothiazolone, n- butylbenzisothiazolone, benzimidazole derivatives such as carbendazim, thiabendazole, methyl 2-benzimidazole carbamate, and their salts, triazole and imidazole derivatives such as tebuconazole and propiconazole, iodine compounds such as iodopropinyl butylcarbamate, diidomethyltolyl sulphone, pyridine derivatives such as zinc pyrithione and 2, 3,5,6- tetrachloro-4-methylsulphonylpyridine, triazine derivatives such as terbutryn, prometryn and Irgarol 1051, urea derivatives such as diuron, isoproturon, dithiocarbamates such as ziram, thiram, hydroxylamine derivatives such as the potassium and aluminium salts of N- cyclohexyl-N-nitrosohydroxylamine, and 2-(thiocyanatomethylthio)benzothiazole (TCMTB), benzothiophene-2-cyclohexylcarboxamide S,S-dioxide and tetrachloroisophthalonitrile. Combinations of the abovementioned preservatives are also contemplated. In an aspect, the preservative can include 3-iodoprop-2~yn-l-yl butylcarbamate; methylbenzimidazole-2-yl carbamate; 3-(3,4-dichloiphenyl)~l ,l~dim ethylurea; 2-tert-butylamino-4~ethylamino-6- methylthio-l,3,5-triazin; 3 -(4-isopropylphenyl)- 1,1 -dimethylurea; zinc pyrithione; 2-octyh 2H-isothiazol-3-one; 4,5-dichloro-2-octyl-4-isothiazolin-3-one; 2-(tert-butylamino)~4- (cyclopropyiamino)-6-(methylthio)-s-triazine; N-tert-butyl-6-chloro-N'-ethyl-l,3,5-triazine-2,4-diamine; or combinations thereof.

[0050] If present, the preservative can be used in an amount of 0.1 to 10 wt%, 0.2 to 5 wt%, or 0.5 to 5 wt% based on a dry weight of the aqueous coating composition. The amount of the preservative can be 0.01 to 5 wt%, 0.05 to 5 wt%, or 0.1 to 5 wt%, based on a total weight of the aqueous coating composition.

[0051] The solids content of the aqueous coating composition can be 40 to 90 wt%, 50 wt% to 85 wt%, or 60 to 80 wt%. As used herein, an aqueous coating composition means that the composition includes water as the main carrier for the (meth)acrylate polymer and the polycarbonate-containing polyurethane. Water can be present in an amount of 5 to 40 wt%, 10 to 30 wt%, 15 to 30 wt%, or 20 to 30 wt%, based on a total weight of the aqueous coating composition.

[0052] As a specific example, the aqueous coating composition can comprise, each based on a dry weight of the aqueous coating composition, 25 to 70 wt%, 30 to 65 wt%, 35 to 60 wt%, or 40 to 55 wt% of a (meth)acrylate polymer, which can be a self-crosslinking (meth)arylate copolymer; 20 to 70 wt% or 25 to 60 wt%, such as 35 to 60 wt%, 40 to 55 wt%. 25 to 55 wt%, 25 to 50 wt%, or 25 to 45 wt% of a polycarbonate-containing polyurethane, which can be an aliphatic polycarbonate-containing polyurethane; 0.5 to 15 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, 1 to 5 wt%, 1 to 15 wt%, or 2 to 10 wt%, or 5 to 10 wt% of a coalescent, which can be a compound of formula (2), preferably an ester alcohol where R2has a hydroxyl substituent; and 0.5 to 15 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, 1 to 10 wt%, or 3 to 10 wt% of an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative. For the additive, the aqueous coating composition can comprise, if present, 0.1 to 5 wt%, 0.2 to 3 wt%, or 0.5 to 2,5 wt% of a surface-active additive such as a polyoxyalkylene silicon oil; 0.05 to 5 wt%, 0.1 to 5 wt%, or 0.5 to 4 wt% of a rheology modifier such as a hydrophobically modified ethylene oxide urethane; 0.05 to 5 wt%, 0.1 to 5 wt%, or 0.5 to 4 wt% of a lubricant such as a polydimethylsiloxane; a polyether-modified polydimethylsiloxane, a polymethylalkylsiloxane, or a combination thereof, and 0.01 to 5 wt%, 0.05% to 2 wt%, or 0.1 to 2 wt% of a surfactant; and optionally 0.1 to 10 wt%, 0.2 to 5 wt%, or 0.5 to 5 wt% of a preservative, each based on a dry weight of the aqueous coating composition. Water can be present in an amount of 5 to 40 wt%, 10 to 30 wt%, 15 to 30 wt%, or 20 to 30 wt%, based on a total weight of the aqueous coating composition.

[0053] As another specific example, the aqueous coating composition can comprise, each based on a total weight of the aqueous coating composition, 20 to 50 wt%, 25 to 45wt%, or 30 to 40 wt% of a (meth)acrylate polymer, which can be a self-crosslinking (meth)arylate copolymer; 20 to 50 wt% or 25 to 45 wt%, such as 30 to 40 wt% of a polycarbonate-containing polyurethane, which can be an aliphatic polycarbonate-containing polyurethane; 0.5 to 10 wt%, 0.5 to 8 wt%, 0.5 to 5 wt%, 1 to 5 wt% of a coalescent, which can be a compound of formula (2), preferably an ester alcohol where R2has a hydroxyl substituent; and 0.1 to 10 wt%, 0.5 to 10 wt%, 0.5 to 5 wt%, 1 to 5 wt%, of an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative. For the additive, the aqueous coating composition can comprise, if present, 0.1 to 5 wt%, 0.2 to 3 wt%, or 0.5 to 2.5 wt% of a surface-active additive such as a polyoxyalkylene silicon oil; 0.05 to 5 wt%, 0.1 to 5 wt%, or 0.5 to 4 wt% of a rheology modifier such as a hydrophobically modified ethylene oxide urethane; 0.05 to 5 wt%, 0.1 to 5 wt%, or 0.5 to 4 wt% of a lubricant such as a polydimethylsiloxane; a polyether-modified polydimethylsiloxane, a polymethylalkylsiloxane, or a combination thereof, 9.01 to 5 wt%, 0.05% to 2 wt%, or 0.1 to 2 wt% of a surfactant; and optionally 0.1 to 5 wt%, 0.05 to 5 wt%, or 0.1 to 5 wt% of a preservative, each based on a dry weight of the aqueous coating composition. Water can be present in an amount of 5 to 40 wt%, 10 to 30 wt%, 15 to 30 wt%, or 20 to 30 wt%, based on a total weight of the aqueous coating composition.

[0054] Preferably, the aqueous coating composition as described herein is a one- package coating composition.

[0055] The aqueous coating composition can be applied to various substrates such as metallic substrates, polymeric substrates, composite substrates, and the like by any of the suitable application methods, such as spraying, knife coating, spreading, pouring, dipping, impregnating, trickling or rolling, for example. In the course of such application, the substrate to be coated may itself be at rest, with the application equipment or unit being moved. Alternatively the substrate to be coated may be moved, with the application unit being at rest relative to the substrate or being moved appropriately.

[0056] Optionally, prior to the application of the aqueous coating composition to the substrate, the substrate may first be coated with a primer or a primer system which may comprise several layers. Thus, the primer system may include an anti-erosion primer optionally followed by a layer of an adhesion-promoting primer.

[0057] After drying, a coating is formed or derived from the aqueous coating composition. The coating can comprise the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and the additive. The coating can have a thickness of 5 microns to 5 millimeters, 10 microns to 2 millimeters, or50 microns to 1 millimeter.

[0058] The coating can provide protection to various articles and used in the industries such as energy (i.e., wind turbine blades, solar panels) and transportation (automotive, marine). In an aspect, the coated article is a component for a wind turbine, for example a rotor blade. A rotor blade assembly for a wind turbine can comprise a rotor blade, and a coating disposed on a surface of the rotor blade, wherein the coating is formed from the aqueous coating composition as described herein.

[0059] The rotor blade assembly can be included in a wind turbine. The turbine can include a tower, generator, gearbox, nacelle, and one or more rotor blades coated with a coating formed from the aqueous coating composition as described herein. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator can then convert the mechanical energy to electrical energy that may be deployed to a utility grid. Byusing the aqueous coating composition as described herein, the wind turbine can have prolonged service life.

[0060] In another aspect, the coated article can be a solar panel. A coated photovoltaic device can comprise a photovoltaic device having a first surface for receiving incoming light and an opposing second surface, and a coating disposed on at least the first surface, the second surface, or both the first and second surfaces of the photovoltaic device, wherein the coating is formed or derived from the coating composition as described herein.EXAMPLES

[0061] The impact resistance of coatings having a thickness of 2 to 4 mils were tested. The coatings were derived from a coating composition including a self-crosslinking (meth)arylate copolymer, an aliphatic polycarbonate-containing polyurethane, a coalescent, which is an ester alcohol of Formula 2 where R2has a hydroxyl substituent, and an additive comprising a polyoxyalkylene silicon oil as a surface active agent, a hydrophobically modified ethylene oxide urethane as a rheology modifier, a surfactant, a lubricant, and a preservative as described herein. The coating composition was applied to plastic substrates and dried to form the coatings. The coated samples had an average thickness of 0.225 inch.

[0062] A test deck was constructed using a sheet of plywood sheathing, flush and securely fastened to a wood frame deck. Small holes were drilled into each plastic sample near their comers. Samples were secured to the test deck using wood deck screws fastenedthrough each hole. Samples were tested in substantial conformance with test standard IEC 61215-2 section MQT 17 (Hail Test). MQT 17 uses frozen solid ice balls propelled perpendicular to test specimens at free-fall velocities of similar size hailstones. Each ice ball is weighed with a precision scale, projectile speeds are measured with a ballistics chronograph, and impact kinetic energies are computed. Each sample was tested with ice balls measuring 35, 45, and 55 millimeter (mm) in diameter in accordance with target parameters summarized in Table 1. According to MQT 17, ice balls must weigh and have projectile speeds within 5-percent of values listed in Table 1.Table 1

[0063] Samples were stored at laboratory ambient conditions for several days prior to testing. Laboratory temperature while testing was 71 degrees F, and relative humidity was 37 percent. Testing was conducted by impacting three target locations with one ice ball of each size listed in Table 1. Impacts were sufficiently separated to ensure each impact had no influence on other impact locations.

[0064] After testing was completed, each sample was examined for cracks, broken, or flaked away coating. Samples were examined visually, under magnification, and with high intensity back-lighting. No damage to any of the coating samples was detected at any of the ice ball impact locations. Ice ball weights, speeds, and computed kinetic energies for each impact made during testing are listed in Table 2.Table 2*foot per second** foot pound force

[0065] In summary, the coated samples were subjected to impacts by simulated hailstones (frozen solid ice balls) propelled perpendicular at velocities consistent with freefall speeds of hailstones measuring 35, 45, and 55 mm in diameter, and in accordance with IEC 61215-2 (MQT 17). The results indicate that individual ice ball impacts did not crack or otherwise break any of the coatings.

[0066] Set forth are various aspects of the disclosure.

[0067] Aspect 1. An aqueous coating composition comprising: a (meth)acrylatepolymer, a polycarbonate-containing polyurethane, a coalescent, and optionally an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative.

[0068] Aspect 2. The aqueous coating composition of aspect 1, wherein the (meth)acrylate polymer and the polycarbonate-containing polyurethane have a weight ratio of 4:1 to 1:4.

[0069] Aspect 3. The aqueous coating composition of aspect 1 or aspect 2, wherein the (meth)acrylate polymer and the polycarbonate-containing polyurethane are present in the aqueous coating composition in a total combined weight of 65 wt% to 97 wt%, based on a dry weight of the aqueous coating composition.

[0070] Aspect 4. The aqueous coating composition of any one of aspects 1 to 3, wherein the (meth)acrylate polymer is a self-crosslinking (meth)acrylate copolymer.

[0071] Aspect 5. The aqueous coating composition of any one of aspects 1 to 4, wherein the polycarbonate-containing polyurethane has carbonate linkages comprising repeating structure of the formulawherein each occurrence of R is independently a C1-30aliphatic group.

[0072] Aspect 6. The aqueous coating composition of any one of aspects 1 to 5, wherein the coalescent has the formulaR1— [C(O)— X— O]n— R2, wherein R1is a C1.30 organic group, X is a single bond or a divalent C1.10 organic group, R2is hydrogen or a C1-30organic group, and n is 1 to 10.

[0073] Aspect 7. The aqueous coating composition of aspect 6, wherein R1is a C1-10organic group, X is a single bond, R2is a C1.10 organic group, and n is 1, and preferably R1is a C1-10, C2-8, or C2-5alkyl, R2is a C1-15, C3-10, or C5-10alkyl with a hydroxyl substituent, X is a single bond, and n is 1.

[0074] Aspect 8. The aqueous coating composition of any one of aspects 1 to 7, wherein the aqueous coating composition comprises the coalescent in an amount of 0.5 to 15 wt%, based on a dry weight of the aqueous coating composition.

[0075] Aspect 9. The aqueous coating composition of any one of aspects 1 to 8, wherein the aqueous coating composition comprises the surface-active agent in an amount of 0.1 to 5 wt%, based on a dry weight of the aqueous coating composition.

[0076] Aspect 10. The aqueous coating composition of aspect 9, wherein the surface-active agent comprises a polyoxyalkylene silicone oil.

[0077] Aspect 11. The aqueous coating composition of any one of aspects 1 to 10, wherein the aqueous coating composition comprises the rheology modifier in an amount of 0.05 wt% to 5 wt%, based on a dry weight of the aqueous coating composition.

[0078] Aspect 12. The aqueous coating composition of aspect 11, wherein the rheology modifier comprises a hydrophobically modified ethylene oxide urethane rheology modifier.

[0079] Aspect 13. The aqueous coating composition of any one of aspects 1 to 12, wherein the aqueous coating composition comprises 0.05 to 5 wt% of the lubricant, based on a dry weight of the aqueous coating composition.

[0080] Aspect 14. The aqueous coating composition of aspect 13, wherein the lubricant comprises at least one of a polydimethylsiloxane, a polyether-modified polydimethylsiloxane, or a polymethylalkylsiloxane.

[0081] Aspect 14A. The aqueous coating composition of any of aspects 1 to 14, wherein the preservative is present in an amount of 0.1 to 10 wt%, based on a dry weight of the aqueous coating composition.

[0082] Aspect 14B, The aqueous coating composition of any of aspects 1 to 14A, wherein the aqueous coating composition comprises 20 to 50 wt% of water, based on a total weight of the aqueous coating composition.

[0083] Aspect 15. The aqueous coating composition of any one of aspects 1 to 14B, wherein the aqueous coating composition is a one-pack composition.

[0084] Aspect 16. A coated article comprising: a substrate; and a coating disposed on a surface of the substrate, wherein the coating is formed from the aqueous coating composition of any one of aspects 1 to 15, and wherein the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.

[0085] Aspect 17. A rotor blade assembly for a wind turbine comprising: a rotor blade, and a coating disposed on a surface of the rotor blade, wherein the coating is formed from the aqueous coating composition of any one of aspects 1 to 15, and the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate- containing polyurethane, the coalescent, and optionally the additive.

[0086] Aspect 18. A wind turbine comprising the rotor blade assembly of aspect 17.

[0087] Aspect 19. A method for forming a coated article, the method comprising: providing an article; applying the aqueous coating composition of any one of aspects 1 to 15on a surface of the article; allowing the aqueous coating composition to dry to form a coating, wherein the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.

[0088] Aspect 20. The method of aspect 19, wherein the article is a rotor blade assembly or a solar panel.

[0089] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate components or steps herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any steps, components, materials, ingredients, adjuvants, or species that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0090] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “Or” means “and / or” unless clearly indicated otherwise by context. The modifier “about” used in connection with a quantity is inclusive of the stated value (e.g., “about 25-50 wt%” is a disclosure of “25-50 wt.%”) and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The terms “about”, “substantially” and “generally” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and / or “substantially” and / or “generally” can include a range of ± 8% or 5%, or 2% of a given value. A dry weight of the coating composition can also be referred to as the dry weight of the final coat.

[0091] “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. A “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0092] Unless otherwise indicated, each of the foregoing groups can be unsubstituted or substituted, provided that the substitution does not significantly adversely affect synthesis, stability, or use of the compound. The term “substituted” as used herein means that at least one hydrogen on the designated atom or group is replaced with another group, provided that the designated atom’s normal valence is not exceeded.

[0093] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. If a term in the present application contradicts or conflicts with a term in an incorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

[0094] While embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.

Claims

CLAIMSWhat is claimed is:

1. An aqueous coating composition comprising: a (meth)acrylate polymer, a polycarbonate-containing polyurethane, a coalescent, and optionally an additive comprising at least one of a surface-active agent, a rheology modifier, a surfactant, a lubricant, or a preservative.

2. The aqueous coating composition of claim 1, wherein the (meth)acrylate polymer and the polycarbonate-containing polyurethane have a weight ratio of 4:1 to 1:4.

3. The aqueous coating composition of claim 1, wherein the (meth)acrylate polymer and the polycarbonate-containing polyurethane are present in the aqueous coating composition in a total combined weight of 65 wt% to 97 wt%, based on a dry weight of the aqueous coating composition.

4. The aqueous coating composition of claim 1, wherein the (meth)acrylate polymer is a self-crosslinking (meth)acrylate copolymer.

5. The aqueous coating composition of claim 1, wherein the polycarbonate- containing polyurethane has carbonate linkages comprising repeating structure of the formulawherein each occurrence of R is independently a C1-30aliphatic group.

6. The aqueous coating composition of claim 1, wherein the coalescent has the formulaR1— [C(O)— X— O]n— R2wherein R1is a C1-30organic group, X is a single bond or a divalent C1-10organic group, R2is hydrogen or a Ci-30 organic group, and n is 1 to 10.

7. The aqueous coating composition of claim 6, wherein R1is a C1-10organicgroup, X is a single bond, R2is a C1-10organic group, and n is 1.

8. The aqueous coating composition of claim 1, wherein the aqueous coating composition comprises the coalescent in an amount of 0.5 to 15 wt%, based on a dry weight of the aqueous coating composition.

9. The aqueous coating composition of claim 1, wherein the aqueous coating composition comprises the surface-active agent in an amount of 0.1 to 5 wt%, based on a dry weight of the aqueous coating composition.

10. The aqueous coating composition of claim 9, wherein the surface-active agent comprises a polyoxyalkylene silicone oil.

11. The aqueous coating composition of claim 1, wherein the aqueous coating composition comprises the rheology modifier in an amount of 0.05 wt% to 5 wt%, based on a dry weight of the aqueous coating composition.

12. The aqueous coating composition of claim 11, wherein the rheology modifier comprises a hydrophobically modified ethylene oxide urethane rheology modifier.

13. The aqueous coating composition of claim 1, wherein the aqueous coating composition comprises 0.05 to 5 wt% of the lubricant, based on a dry weight of the aqueous coating composition.

14. The aqueous coating composition of claim 13, wherein the lubricant comprises at least one of a polydimethylsiloxane, a polyether-modified polydimethylsiloxane, or a polymethylalkylsiloxane.

15. The aqueous coating composition of claim 1, wherein the aqueous coating composition is a one-pack composition.

16. A coated article comprising: a substrate; and a coating disposed on a surface of the substrate, wherein the coating is formed from the aqueous coating composition of claim 1, and wherein the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.

17. A rotor blade assembly for a wind turbine comprising: a rotor blade, and a coating disposed on a surface of the rotor blade, wherein the coating is formed from the aqueous coating composition of claim 1 , and the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.

18. A wind turbine comprising the rotor blade assembly of claim 17.

19. A method for forming a coated article, the method comprising: providing an article; applying the aqueous coating composition of claim 1 on a surface of the article; allowing the aqueous coating composition to dry to form a coating, wherein the coating comprises the (meth)acrylate polymer or a crosslinked product thereof, the polycarbonate-containing polyurethane, the coalescent, and optionally the additive.

20. The method of claim 19, wherein the article is a rotor blade assembly.

Images