TWO-PART (2K) WATER-BASED COATING COMPOSITION

Abstract

A two-part (2K) water-based coating composition containing: a) a binder part comprising: (a1) at least one hydroxyl-functional (meth)acrylate copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups; and b) a crosslinking part comprising at least one polyisocyanate compound with pendant -NCO groups, wherein the non-aromatic polyester of component (a2) has a number average molecular weight (Mn) of 500 to 5000 Daltons, an acid number of about 0 to about 30 mg KOH / g, a calculated hydroxyl number of about 100 to about 600 mg KOH / g, and a calculated hydroxyl functionality of about 2 to about 8; and wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is 5:1 to 1:5.

Description

TECHNICAL FIELDThe present disclosure relates to a two-part (2K) water-based coating composition containing a binder part and a cross-linking part. The binder portion comprises a water-dilutable hydroxyl-functional (meth)acrylate copolymer and a non-aromatic polyester having active hydrogen groups. The cross-linking portion of the composition comprises at least one polyisocyanate compound having pendant -NCO groups. The coating composition can be used as a clearcoat composition used in vehicle finish or refinishing.GENERAL STATE OF THE ARTAuto refinish refers to compositions and methods used in the repair of damaged auto finishes, typically, but not necessarily, to a finish provided by the First Out Tester (OEM). For example, the damaged motor vehicle component may include a defective region(s) in which previously deposited coating layers (in) have been at least partially removed, and such removal may have exposed the bare substrates of the component under certain circumstances. The repair operations may therefore include repair or replacement of the entire damaged body part, repair of one or more coating layers disposed on the components, or a combination of both methods. The size of the defective area and the presence or absence of coating layers surrounding the defective area, which if present can serve as anchors for the repair coating compositions, are often critical to the type of work performed.With respect to repair of coating layers, the refinish process generally comprises the following sequential steps: grinding the surface to be repaired; applying at least one layer of a primer composition; optionally grinding the applied primer composition; applying at least one layer of a basecoat composition to achieve the desired visual appearance, such as desired color, gloss, or sharpness of image (DOI); and applying a clearcoat composition which may be sufficiently transparent or translucent to allow the underlying coating layer(s) to be seen therethrough.In the past, the coating compositions used in refinish operations - including the clearcoat compositions - were solvent based and therefore contained significant amounts of volatile organic compounds (VOCs). However, the use of such compounds is regulated. In the United States, for example, the emission standards for volatile organic compounds are regulated by Clean Air Act (Law) section 183(e), and with respect to the transmission levels for auto repair resists, reference may be made to 42 United States Code (U.S.C.) §7511b(e) and 40 Code of Federal Regulations (CFR) Part 59 Subpart B.Recently, the lacquer industry has made considerable advances in meeting government and federal regulations on VOC emissions through the development of high solids solvent-based coating compositions and water-based coating compositions.Unlike existing solvent-based alternatives, water-based coating compositions can not only have the desired wetting and flow properties for refinish applications, but can also be easily used by users without having to re-adjust the existing applicators. However, water-based compositions must dry out to allow them to crosslink and cure properly. In view of boiling point, water removal by rapid drying may be difficult to achieve because water removal conventionally requires quite severe baking conditions where air agitation and humidity in the oven or drying booth must be carefully controlled.Because drying aqueous compositions can be an energetic burden and retard the refinish process, volatile organic co-solvents or diluents have been incorporated into such compositions to improve their drying properties. However, the presence of such co-solvents and diluents may be undesirable in the future as the above regulations on the allowable VOC levels in auto repair paint compositions become more stringent.It is therefore desirable to develop water-based coating compositions that have comparable properties to their solvent-based precursors. In particular, such water-based compositions should have good flow on the application surface and-after application-should be dehydratable under moderate or low stoving conditions. Further, such compositions may have suitable optical properties to facilitate their use in paint and refinish applications, for example, as clearcoat compositions.Other advantageous features and characteristics of the various compositions will become apparent from the following detailed description and examples.SUMMARYThis disclosure provides a two-part (2K) water-based coating composition comprising:Water; a) a binder portion comprising:(a1) at least one water-dilutable hydroxyl-functional (meth)acrylate copolymer; and(a2) at least one non-aromatic polyester having active hydrogen groups; andb) a crosslinking portion comprising at least one polyisocyanate compound having pendant -NCO groups,wherein the non-aromatic polyester of component (a2) has a number average molecular weight (Mn) of about 500 to about 5000 daltons, an acid number of about 0 to about 30 mg KOH / g, a calculated hydroxyl number of about 100 to about 600 mg KOH / g, and a calculated hydroxyl functionality of about 2 to about 8; andwherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is about 5:1 to about 1:5.The disclosure further provides a cured product obtained from the two-part (2K) water-based coating composition.The present disclosure also provides an article comprising: a metal substrate; and a multilayer coating disposed on the metal substrate, wherein at least one layer of the multilayer coating comprises the cured product. In one embodiment of the article, the multi-layer coating comprises: a basecoat disposed on and in direct contact with the substrate; at least one basecoat comprising a color and / or visual effect imparting compound, wherein a basecoat is disposed on and in direct contact with the basecoat; and a clearcoat comprising the cured product, wherein the clearcoat is disposed on and in direct contact with a basecoat.Where aspects of the disclosure are described herein with certain embodiments, one or more of these embodiments may be implemented in or combined with any other embodiment, unless otherwise stated, even if this combination is not expressly described. In other words, the described embodiments are not mutually exclusive unless stated, and their combinations are included within the scope of this disclosure.BRIEF DESCRIPTION OF THE DRAWINGSVarious other objects, advantages and features of the disclosure will become apparent to those skilled in the art from the following discussion taken in conjunction with the accompanying drawings, wherein: FIG. 1 is a side cross-sectional view of an article according to a first embodiment of the present disclosure; and FIG. 2 is a side cross-sectional view of an article according to a second embodiment of the present disclosure.DETAILED DESCRIPTIONThe following detailed description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. Moreover, it is not intended to be bound by the theory set forth in the prior art or in the following detailed description.Embodiments of the present disclosure generally relate to water-dilutable, hydroxyl-functional (meth)acrylate copolymers, non-aromatic polyesters having active hydrogen groups, compositions containing them, and methods for their preparation. For the sake of brevity, conventional techniques for preparing such polymers and compositions will not be described in detail herein. Moreover, the various tasks and method steps described herein may be incorporated into a more comprehensive method or process having additional steps or functions not described in detail herein. In particular, various steps in the preparation of such polymers and associated compositions are known, so for brevity, some conventional steps will be described briefly or omitted altogether without providing the known process details.The polymers and compositions disclosed herein may suitably comprise, consist of, or consist essentially of the components, elements, and process limitations described herein. The embodiments exemplarily disclosed herein may be suitably performed in the absence of an element not specifically disclosed herein.DEFINITIONSThe term "consisting essentially of" may describe various non-limiting embodiments free of one or more optional compounds described herein or one or more additives, solvents, polymers, resins, etc., not described herein but used in the art.The term "about" may describe values of ±0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% in various embodiments. Moreover, in various non-limiting embodiments, it should be noted that all numerical values given herein, except for the specific examples, are approximate values, wherein the endpoints or particular values are to be understood as "about" or "about" the given values.The molecular weights referred to in this specification are typically measured by gel permeation chromatography (GPC) using polystyrene calibration standards as set forth in ASTM 3536.As used herein, the "acid number" is the mass of potassium hydroxide (KOH) in milligrams required to neutralize one gram of the composition indicated. The acid number can be determined by potentiometric analysis.As used herein, the term "hydroxyl number" is defined as the mass in milligrams of potassium hydroxide required to neutralize the acetic acid taken up in acetylation of one gram of a chemical containing free hydroxyl groups. The hydroxyl number can be determined according to DIN 53240.The term "active hydrogen atoms" refers to hydrogen atoms having activity according to the Zerewitinoff test as described by Kohlerin J. Am. Chem. Soc., 49, 3181 (1927), which is expressly incorporated herein by reference in its entirety in various non-limiting embodiments. Active hydrogen atoms may be derived from hydroxyl, thiol, primary amine, secondary amine and carboxyl groups.The term softening point (°C) as used herein with respect to waxes is the ring and ball softening point, which unless otherwise stated is measured according to ASTM E28.Unless otherwise stated, the viscosities of the compositions described herein are measured with the Brookfield viscometer, model CAP2000, under standard conditions of 20°C and 50% relative humidity (RH). The viscometer is calibrated with hydrocarbon oils of known viscosities ranging from 1 to 10,000 centipoise. For calibration, a set of RV spindles is used which are fastened to the viscometer. The measurements of the coating compositions are made with No. 4 spindle at a speed of 400 revolutions per minute for one minute until the viscometer is equilibrated. The viscosity corresponding to the equilibrium value is then calculated from the calibration.Unless otherwise indicated, the term "particle size" refers to the largest axis of the particle. In the case of a generally spherical particle, the major axis is the diameter.The term "median volume particle size" (Dv50) as used herein refers to a particle size where 50% of the volume of the particles sampled is greater and 50% of the volume of the particles sampled is less than the indicated Dv50value. Similarly, the term "Dv90", when used, refers to a particle size where 90% of the volume of the particles being sampled is less than and 10% of the volume of the particles being sampled is greater than the indicated Dv90 value. The particle size is determined here by laser diffraction using the Anton Pair Particle Size Analyzer (PSA) 1190.The room temperature as used herein is 23° C. plus or minus 2° C.The term "ambient conditions" refers to the temperature and pressure of the environment in which the composition is located or in which a coating layer or substrate of the coating layer is located.For the purposes of the present disclosure, "two-part (2K) compositions" are understood to mean compositions in which a first part a) and a second part b) are stored in separate vessels on account of their (high) reactivity. The two parts are mixed only before or during use and then react, typically without additional activation, to form a bond and thus form a polymeric network. Higher temperatures may be employed herein to promote the crosslinking reaction.The term "water-dilutable (co)polymer" as used herein refers to a (co)polymer which is present in the form of particles in water, wherein the particles are dispersed or suspended and are generally stable against flocculation upon further dilution with water. In contrast to a water soluble (co)polymer, a dilute solution (about 1 g / L) of a water dilutable polymer exhibits scattering when analyzed by dynamic light scattering or other technique known in the particle analysis art.The term "clear coat" is used herein to refer to a coating layer within a multilayer coating that is sufficiently transparent or translucent to allow the underlying coating layer(s) to be seen therethrough. The term "clear" does not require absolute transparency or light transmission.The term "metallic" as used herein refers to any type of metal, metal alloy, or mixture thereof. As used herein, the term "alloy" refers to a substance consisting of two or more metals or a metal and a nonmetal which are intimately joined together, usually by fusion and dissolution in the melt.As used herein, the term "catalytic amount" means a ssub stoichiometric amount of the catalyst relative to a reactant, unless expressly stated otherwise.As used herein, the term "free radical initiator" refers to compounds which upon sufficient exposure to energy, e.g., in the form of light or heat, decompose into uncharged moieties, each of which, however, has at least one unpaired electron. In particular, a thermal radical initiator generates free radicals upon activation by thermal energy, e.g., upon heating or irradiation in the infrared or microwave range.All isomers and chiral options for each compound described herein are expressly intended for use herein in various non-limiting embodiments.It is understood that the indices of the polymers are typically described as averages, since the synthesis of polymers typically results in a distribution of different individual molecules.As used herein, the term "monomer" refers to a substance that can be subjected to a polymerization reaction to contribute constitutional units to the chemical structure of a polymer. The term "monofunctional" as used herein refers to the ownership of a polymerizable moiety. The term "polyfunctional" as used herein refers to the ownership of more than one polymerizable moiety.The term "blocked" as used herein refers to a compound having a "blocking group" such that its reactive functionality is not available until the blocking group is removed or degraded. The blocking group may be selectively removed or degraded at an appropriate point in the synthesis sequence: the triggering event may be, inter alia, moisture, heat or radiation. Examples of blocked isocyanates include those that have co-reacted with phenol, methylethyl ketoxime or ε-caprolactam.The term "fatty acid" as used herein is a monocarboxylic acid consisting of an aliphatic chain having 4 to 22 carbon atoms and a terminal carboxyl group (COOH). The fatty acid may be saturated or unsaturated, branched or unbranched and may or may not contain one or more hydroxyl group(s). Exemplary fatty acids include: linoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxy stearic acid, linolenic acid and eiconsanic acid.The term "dimer fatty acid" is interchangeable with "dimerized fatty acid" and generally refers to a compound having two fatty acid subunits in which the respective fatty acid side chains are covalently bonded to each other via a bond or a linking group. Thus, a fatty acid dimer as described herein is a covalent fatty dimer. The dimer fatty acid may be a heterodimer or homodimer and may be cyclic or noncyclic. The term is intended to include derivatives of dimer fatty acids having carboxyl functional groups which, upon reaction with glycols and diols to form polyesters, behave substantially like dicarboxylic acids: esters and ester-forming reactive derivatives such as acid halides and anhydrides are to be mentioned here.As used herein, "meth)aryl" is an abbreviation that refers to "acrylic" and / or "methacrylic.". The term "(meth)acrylamide" thus refers to both acrylamide and methacrylamide.As used herein, "C 1- C n- alkyl" refers to a monovalent group or moiety of from 1 to n carbon atoms which is a radical of an alkane and includes straight and branched organic groups. Thus, "C I- C, 8- alkyl" refers to a monovalent group or moiety of 1 to 18 carbon atoms which is a radical of an alkane and includes straight and branched organic groups. Examples of alkyl groups include: methyl; ethyl; propyl; isopropyl; n-butyl; isobutyl; sec-butyl; tert-butyl; n-pentyl; n-hexyl; n-heptyl; and 2-ethylhexyl. In the present disclosure, these alkyl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a particular moiety (R), the specification describes a tolerance for one or more non-halogen substituents within an alkyl group.The term "C 1- C 18- hydroxyalkyl" as used herein refers to an HO (alkyl) group having from 1 to 18 carbon atoms wherein the point of attachment of the substituent is via the oxygen atom and the alkyl group is as defined above.An "alkoxy group" refers to a monovalent group represented by -OA, wherein A represents an alkyl group: non-limiting examples thereof are a methoxy group, an ethoxy group, and an iso-propyloxy group. The term "C 1- C 18- alkoxyalkyl" as used herein refers to an alkyl group or moiety having an alkoxy substituent as defined above, wherein the moiety (alkyl-O-alkyl) has a total of 1 to 18 carbon atoms: Such groups include methoxymethyl (-CH 2 OCH 3), 2- methoxyethyl (-CH 2 CH 2 OCH 3) and 2-ethoxyethyl. Similarly, the term "C 7- C 18- alkoxyaryl" as used herein refers to an aryl group having an alkoxy substituent as defined above wherein the moiety (aryl-O-alkyl) comprises a total of 7 to 18 carbon atoms.The term "C 2- C 4- alkylene" as used herein is defined as a saturated divalent hydrocarbon radical having from 2 to 4 carbon atoms.The term "C 3- C 18- cycloalkyl" includes a saturated, mono- or polycyclic hydrocarbon group or moiety having from 3 to 18 carbon atoms. In the present disclosure, such cycloalkyl groups or moieties may be unsubstituted or substituted with one or more halogens. Where applicable to a particular moiety (R), the specification specifies a tolerance for one or more non-halogen substituents within a cycloalkyl group. Examples of cycloalkyl groups include: cyclopropyl; cyclobutyl; cyclopentyl; cyclohexyl; cycloheptyl; cyclooctyl; adamantane; and norbornane.As used herein, the term "C 2- C 18- alkenyl" refers to hydrocarbyl groups or moieties having from 2 to 18 carbon atoms and at least one ethylenically unsaturated moiety. The alkenyl group or moiety may be straight chain, branched or cyclic and may be optionally substituted with one or more halogens. Where applicable to a particular moiety (R), the specification specifies a tolerance for one or more non-halogen substituents within an alkenyl group. The term "alkenyl" also includes radicals having "cis" and "trans" configurations, or alternatively "E" and "Z" configurations, as will be appreciated by those of ordinary skill in the art. Examples of C 2- C 20- alkenyl groups include: -CH=CH 2; - CH=CHCH 3; - CH 2 CH=CH 2; - C(=CH 2)( CH 3); - CH=CHCH 2 CH 3; - CH2CH=CHCHCH3; -CH2CH2CH=CH2; -CH=C(CH3)2; CH2C(=CH2)(CH3); -C(=CH2)CH2CH3; -c(ch_ner45_)=chch_ner46_; -c(ch_ner47_)ch=ch_ner48_; -ch=chch_ner49_ch_ner50_ch_ner51_; -ch_ner52_ch=chch_ner53_ch_ner54_; -ch_ner55_ch_ner56_ch=chch_ner57_; -ch_ner58_ch_ner59_ch_ner60_ch=ch_ner61_; -c(=ch_ner62_)ch_ner63_ch_ner64_ch_ner65_; - c(ch_ner66_)=chch_ner67_ch_ner68_; -ch(ch_ner69_)ch=chch; -ch(ch_ner70_)ch_ner71_ch=ch_ner72_; -ch_ner73_ch=c(ch_ner74_)_ner75_ ; 1-cyclopent-1-enyl; 1-cyclopent-2-enyl; 1-cyclopent-3-enyl; 1-cyclohex-1-enyl; 1-cyclohex-2-enyl; and 1-cyclohexyl-3-enyl.As used herein, "C 6- C 18- aryl" alone or as part of a larger moiety - as in "aralkyl group" refers to monocyclic, bicyclic and tricyclic ring systems in which the monocyclic ring system is aromatic or at least one of the rings is aromatic in a bicyclic or tricyclic ring system. The bicyclic and tricyclic ring systems include benzocondensed 2-3-membered carbocyclic rings. In the present disclosure, these aryl groups may be unsubstituted or substituted with one or more halogens. Where applicable to a particular moiety (R), the specification specifies a tolerance for one or more non-halogen substituents within an aryl group. Exemplary aryl groups include: phenyl; (C 1- C 4) alkylphenyl such as tolyl and ethylphenyl; indenyl; naphthalenyl, tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl.As used herein, "alkylaryl" refers to alkyl substituted aryl groups or moieties and "substituted alkylaryl" refers to alkylaryl groups or moieties additionally bearing one or more substituents as described above. As used herein, "aralkyl" further means an alkyl group or moiety substituted with an aryl radical as defined above.The term "hetero" as used herein refers to groups or moieties containing one or more heteroatoms, such as N, O, Si and S. For example, "heterocyclic" refers to cyclic groups containing, for example, N, O, Si or S as part of the ring structure. "heteroalkyl", "heterocycloalkyl" and "heteroaryl" are alkyl, cycloalkyl and aryl groups as defined above containing N, O, Si or S as part of their structure.The term "non-polymeric" is used herein to mean a compound that is not composed of repeating structural units. A non-polymeric compound can be considered a unique, single structural unit.The term "non-aromatic" as used herein as a term for monomers refers to a compound that does not have an aromatic nucleus. The term is intended to include both aliphatic and cycloaliphatic compounds which may be saturated or unsaturated and in the latter case include nonaromatic carbon-carbon double bonds or carbon-carbon triple bonds. Nonaromatic polymeric compounds can be substantially free of aromatic nuclei in their backbone, so that the polymer can contain aromatic nuclei only on account of technical impurities of aliphatic or cycloaliphatic monomer building blocks.The term "base" as used herein refers to a species capable of abstracting a proton in a polar or nonpolar solvent or capable of releasing a hydroxide anion (OH -).In various embodiments, the term "free of" describes embodiments containing less than about 5, 4, 3, 2, 1, 0.5, or 0.1% by weight of the component, compound, moiety, functional group, element, or ion of interest using a suitable weight basis known to one of ordinary skill in the art. In other embodiments, the term "free of" describes embodiments containing about 0% by weight of the component, compound, moiety, functional group, element or ion of interest.The term "anhydrous" as used herein is synonymous with the term "free of water.".As mentioned above, the water-based composition comprises water and: a) a binder portion; and b) a cross-linking portion. The water may be present in an amount of from 30 to 80 wt% based on the weight of the composition. The water may be present, for example, in an amount of 35 to 70 wt %, 40 to 60 wt %, 45 to 55 wt %, 45 to 52 wt %, or 46 to 51 wt %. At this water content, drying and coalescence of the composition, when applied to a substrate, is likely not associated with a great deal of energy and time. Compositions having this water content may be characterized, for example, by a viscosity of less than 500 centipoise, less than 200 centipoise, less than 100 centipoise, less than 50 centipoise, less than 40 centipoise, or even less than 30 centipoise, as measured at room temperature. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.It is not necessary that the water be added to the two-part (2K) composition independently of one or more components or the composition itself. Alternatively, one or more of the components of the composition may be provided in water.In certain embodiments, the binder part a) of the two-part (2K) composition comprises water such that the binder part a) provides at least a portion of the water of the two-part (2K) composition. However, it is not excluded that additional water is added to the composition during or after a binder part a) comprising water and the cross-linking part b) are brought together. The addition of this additional water may serve to reduce the viscosity of the composition, which may be useful for certain methods described below with which the composition may be applied to substrates, such as spraying.PART A)Referring now to binder portion a) of the two-part (2K) water-based composition, this portion comprises: (a1) at least one water-dilutable hydroxyl-functional (meth)acrylic copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups.The at least one hydroxyl functional (meth)acrylate copolymer of component (a1) is water-dilutable, but is typically compatible with polyisocyanates, including hydrophobic polyisocyanates which have not been hydrophilically modified, including polyether or polyester groups. Thus, the two-part coating composition itself is water-dilutable, which can offer the user great flexibility in the application of the coating compositions, for example in vehicle refinishing operations.The presence of the non-aromatic polyester in the binder portion of the composition improves the appearance of the cured coatings obtained therefrom. The non-aromatic polyester may also help the cured coatings to resist weathering.Copolymer component (a1)The at least one water-dilutable hydroxyl-functional (meth)acrylic copolymer can be obtained commercially. Exemplary commercial copolymers include: Bahydrol® brand products available from Covestro; and Setaqua® brand products available from Allnex.However, in one embodiment, the water-dilutable hydroxyl-functional (meth)acrylate copolymer of component (a1) is obtained by polymerization of a monomer mixture comprising, based on the total weight of the monomers in the monomer mixture:10 up to 80% by weight, for example 20 to 60% by weight, of i) of at least one hydroxyl-functional adduct of a mono-epoxy ester and an unsaturated carboxylic acid;0 up to 40 wt %, for example 10 to 30 wt %, ii) of at least one hydroxyl functional unsaturated monomer different from component i);1 up to 8% by weight, for example 2 to 6% by weight, of iii) of at least one unsaturated acid-functional monomer; and0 up to 70 wt %, for example 20 to 60 wt % iv), of at least one polymerizable unsaturated monomer different from monomer components i), ii) and iii).The monomer components of this exemplary copolymer of component (a1) are described in more detail below. It is noted that the polymerization of the component monomers is usually a radical solution polymerization. Two-stage free-radical solution polymerization may be used, an exemplary embodiment being skew feed polymerization.Monomer component i): Hydroxyl-functional adductIn this exemplary embodiment, the monomer mixture comprises 10 to 80 wt % i) of at least one hydroxyl functional adduct of a mono-epoxy ester and an unsaturated carboxylic acid, based on the total weight of monomers in the monomer mixture. For example, the (meth)acrylate copolymer (a1) may comprise 20 to 60% by weight or 30 to 60% by weight i), based on the total weight of the monomers in the monomer mixture, of the at least one hydroxyl-functional adduct. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Typically, the adduct is formed by a nucleophilic addition reaction of the mono-epoxy ester with the acid to form a hydroxyalkyl ester. This ring-opening acidolysis reaction usually requires a catalyst, and tertiary amines, quaternary ammonium compounds and transition metal compounds may be mentioned as examples.The mono-epoxy ester reactants are typically glycidyl esters derived from aliphatic saturated monocarboxylic acids having a tertiary or quaternary carbon atom in the alpha (α) position. Representative mono-epoxy esters are the glycidyl esters of saturated α,α-dialkylalkane monocarboxylic acids having 5 to 13 carbon atoms or 9 to 11 carbon atoms in the acid molecule. Exemplary mono-epoxy ester reactants include: versatic glycidyl ester commercially available as Cardura E10 from Hexion; pivalic glycidyl ester commercially available as Cardura E5 from Hexion; and the reaction product of a tertiary fatty acid having up to 12 carbon atoms and epichlorohydrin.The reactant acid functional compound may be an aliphatic unsaturated monocarboxylic acid, non-limiting examples of which include: α,β-monoethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and isocrotonic acid; C 1- C 6- alkyl half esters of α,β-monoethylenically unsaturated dicarboxylic acids such as fumaric acid and maleic acid; and C 1- C 6- alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids bearing a free carboxylic acid group. In various embodiments, acrylic acid and / or methacrylic acid are the reactant acid functional compound.Monomer component ii): Hydroxyl-functional ethylenically unsaturated monomerIn this exemplary embodiment, the monomer mixture comprises 10 to 30 wt % ii) of at least one hydroxyl functional monomer different from monomer component i), based on the total weight of monomers in the monomer mixture. For example, the monomer mixture may comprise 10 to 25 wt %, or 10 to 20 wt % ii) of the at least one hydroxyl functional monomer, based on the total weight of the monomers in the monomer mixture. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary monomers of component ii) include hydroxyalkyl esters having primary and secondary hydroxyl groups derived from α,β-monoethylenically unsaturated monocarboxylic acids. These may include, for example, hydroxyalkyl esters derived from acrylic acid, methacrylic acid, crotonic acid or isocrotonic acid.In one embodiment, monomer component ii) comprises at least one hydroxyl (meth)acrylate monomer of the formula HMA: H 2 C=CG a CO 2 R h( HMA) wherein: G a is hydrogen, halogen or methyl; and R h is C 1- C 18- hydroxyalkyl.Typical monomers according to formula HMA are those wherein: G a is hydrogen, halogen or methyl; and R h is C 1- C 12- hydroxyalkyl. Monomers wherein G a is hydrogen or methyl and R h is C 1- C 6- hydroxyalkyl may also be used.Examples of (meth)acrylate monomers according to the formula HMA are: hydroxyethyl (meth)acrylate; 1-hydroxypropyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 1-hydroxybutyl (meth)acrylate; 2-hydroxybutyl (meth)acrylate; and 3-hydroxybutyl (meth)acrylate.Monomer component iii): Ethylenically unsaturated acid functional monomerIn this exemplary embodiment, the monomer mixture comprises 2 to 6 wt % iii) of at least one ethylenically unsaturated acid functional monomer based on the total weight of monomers in the monomer mixture. For example, component iii) may constitute from 2 to 5% or from 2 to 4% by weight of the monomer mixture. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Without wishing to limit the present disclosure, the unsaturated acid functional monomers can be selected from: ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, vinyl phosphonic acid, and mixtures thereof. Suitable ethylenically unsaturated sulfonic acids are, for example, vinylsulfonic acid, styrenesulfonic acid and acrylamidomethylpropanesulfonic acid.Typically, monomer component iii) comprises at least one ethylenically unsaturated carboxylic acid selected from: α,β-monoethylenically unsaturated monocarboxylic acids; α,β-monoethylenically unsaturated dicarboxylic acids; C 1- C 6- alkyl half esters of α,β-monoethylenically unsaturated dicarboxylic acids; α,β-monoethylenically unsaturated tricarboxylic acids; C 1- C 6- alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids bearing at least one free carboxylic acid group; and mixtures thereof. In particular, monomer component iii) may comprise at least one ethylenically unsaturated carboxylic acid selected from methacrylic acid, acrylic acid, itaconic acid, maleic acid, aconitic acid, crotonic acid, fumaric acid and mixtures thereof.For the sake of completeness, it should be pointed out that although the unsaturated acid-functional monomer described above can be used in the form of the free acid, it is not excluded that the individual acid groups of the monomers are partially or completely neutralized with suitable bases, provided that this does not impair their participation in the copolymerization reaction.Monomer component iv): Other polymerizable unsaturated monomerIn this exemplary embodiment, the monomer mixture may further comprise at least one ethylenically unsaturated monomer different from the monomers of the above components i), ii) and iii). For example, monomer component iv) may comprise the following, based on the total weight of monomers in the monomer mixture:20 up to 60% by weight, for example 25 to 50% by weight, of iv-1) of at least one (meth)acrylate monomer of the formula MA:H 2 C=CG a CO 2 R a( MA) wherein: G a is hydrogen, halogen or methyl; and R a is: C 1- C 18- alkyl; C 2- C 18- heteroalkyl; C3-C18cycloalkyl; C2-C8heterocycloalkyl; C 2- C 8- alkenyl or C 2- C 8- alkynyl; 0 to 15% by weight, for example 4 to 14% by weight or 10 to 14% by weight iv-2), of at least one vinylaromatic monomer; and 0 to 25% by weight iv-3) of at least one further polymerizable unsaturated monomer which differs from the monomers iv)-1 and iv)-2.In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In typical monomers according to formula MA, G a is hydrogen, halogen or methyl; and R a is C 1- C 18- alkyl or C 3- C 18- cycloalkyl. Monomers in which G a is hydrogen or methyl may also be used.Examples of (meth)acrylate monomers according to formula MA, which may be used alone or in combination, include: methyl (meth)acrylate; ethyl (meth)acrylates; n-butyl (meth)acrylate; isobutyl (meth)acrylate; hexyl (meth)acrylate; 2-ethylhexyl (meth)acrylate; isodecyl (meth)acrylate; dodecyl (meth)acrylate; lauryl (meth)acrylate; stearyl (meth)acrylate; cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; 4-tert-butylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; Dihydrodicyclopentandienyl(meth)acrylat; ethylene glycol monomethyl ether (meth)acrylate; Ethylenglykolmonoethylether(meth)acrylat; Ethylenglykolmonododecylether(meth)acrylat; Diethylene glycol monomethyl ether (meth)acrylate; trifluoroethyl (meth)acrylate and perfluorooctyl (meth)acrylate.The (meth)acrylate monomers that form component iv) of the monomer mixture may, in some embodiments, comprise "hard" monomers. The term "hard monomer" typically describes a monomer which, when homopolymerized, would result in a homopolymer having a glass transition temperature (Tg) greater than about 30°C. For example, monomer component iv) may comprise at least one (meth)acrylate monomer considered to be a hard monomer.Exemplary hard monomers include: cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; Dihydrodicyclopentandienyl(meth)acrylat; and 4-tert-butylcyclohexyl (meth)acrylate.As already mentioned, monomers of component iv-2) can be completely excluded from the monomer mixture. However, in other embodiments, the monomer mixture may comprise vinyl aromatic monomers (iv-2). In a representative embodiment, monomer component iv-2) comprises at least one vinyl aromatic monomer of formula (VA): wherein: R 1 is H or C 1- C 4- alkyl; each R 2 is independently hydrogen or C 1- C 4- alkyl; Ar is unsubstituted phenyl or phenyl substituted with 1 to 5 substituents, each substituent being independently halogen or C 1- C 4- alkyl; and n is an integer from 0 to 4.Typical monomers according to formula VA are those wherein: R 1 is H or methyl; each R 2 is independently H or methyl; Ar is unsubstituted phenyl or phenyl substituted with 1 to 5 substituents, each substituent being independently halogen or C 1- C 4- alkyl; and, n is 0 or 1.Examples of vinyl aromatic monomers according to formula (VA) - which may be used alone or in combination - include: styrene; α-methylstyrene; 2-methylstyrene; 3-methylstyrene; 4-4-methylstyrene; 2-tert-butylstyrene; 4-tert-butylstyrene; 2-chlorostyrene; and 4-chlorostyrene.As also mentioned above, the monomer mixture of this embodiment of component (a1) may comprise, based on the total weight of the monomers in the monomer mixture, from 0 to 25 wt% iv-3) of at least one polymerizable unsaturated monomer different from the monomers of components i), ii), iii), iv-1) and iv-2). The monomer mixture may comprise, for example, from 1 to 20% by weight, from 1 to 15% by weight or from 1 to 10% by weight, based on the total weight of the monomers in the monomer mixture, of monomers of component iv-3). Alternatively, monomers of component iv-3) can also be completely excluded. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary monomers that may be present in monomer component iv-3), either alone or in combination, include: aromatic (meth)acrylate monomers; (meth)acrylate functionalized oligomers; nitrogen (N-) functionalized ethylenically unsaturated monomers; silane functional ethylenically unsaturated monomers, such as methacryloxypropyltri(C 1- C 5) alkoxysilanes, and vinyltri(C 1- C 5) alkoxysilanes; acetoacetyl functional unsaturated monomers, such as acetoacetoxyethyl methacrylate; vinyl esters; vinyl and vinylidene halides; vinyl ethers; alkyl vinyl ketones; cycloalkyl vinyl ketones; heterocyclic aliphatic vinyl compounds; poly(meth)acrylates of alkane polyols; poly(meth)acrylates of oxyalkane polyols; and poly(C 2- C 3) alkylene glycol di(meth)acrylates.Suitable aromatic (meth)acrylate monomers include those of formula AII: H 2 C=CG b CO 2 R d( AII) wherein: G b is hydrogen, halogen or methyl; and R b is C 6- C 18- aryl, C 1- C 9- heteroaryl, C 7- C 18- alkoxyaryl, C 7- C 18- alkaryl or C 7- C18aralkyl.Exemplary (meth)acrylate monomers according to formula (AII) - which may be used alone or in combination - include: benzyl (meth)acrylate; phenoxyethyl (meth)acrylate; and phenoxypropyl (meth)acrylate.Suitable (meth)acrylate functionalized oligomers can be selected from (meth)acrylate functionalized polyurethanes, (meth)acrylate functionalized polybutadienes, (meth)acrylic polyol (meth)acrylates, polyester (meth)acrylate oligomers, polyamide (meth)acrylate oligomers, polyether (meth)acrylate oligomers and mixtures thereof. The oligomers may have one or more acrylate and / or methacrylate groups attached to the oligomeric backbone, wherein the (meth)acrylate functional groups may be located at a terminal position on the oligomer and / or may be distributed along the oligomeric backbone. It is typical that the (meth)acrylate functionalized oligomer reacted as monomer in deriving copolymer (a1) has two or more (meth)acrylate functional groups per molecule; and / or has a weight average molecular weight (Mw) of about 300 to about 1000 daltons. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In the case of the (N)-functionalized ethylenically unsaturated monomers, the nitrogen-functionalized groups can be either nitrile or urea or contain imide, amide or amine substituents.Exemplary nitrile monomers include acrylonitrile and methacrylonitrile. Exemplary maleimide monomers include: maleimide; methylmaleimide; ethylmaleimide; propylmaleimide; butylmaleimide; hexylmaleimide; octylmaleimide; dodecylmaleimide; stearylmaleimide; phenylmaleimide; and cyclohexylmaleimide. Exemplary (meth)acrylamides include: acryloyl morpholine; diacetone (meth)acrylamide; N-methyl (meth)acrylamide; N-ethyl (meth)acrylamide; N-isopropyl (meth)acrylamide; N-tert-butyl (meth)acrylamide; N-hexyl (meth)acrylamide; N-cyclohexyl (meth)acrylamide; N-octyl (meth)acrylamide; N-tert-octyl (meth)acrylamide; N-dodecyl (meth)acrylamide; N-benzyl (meth)acrylamide; N-(hydroxymethyl)acrylamide; N-isobutoxymethylacrylamide; N-butoxymethylacrylamide; N,N-dimethyl (meth)acrylamide; N,N-diethyl (meth)acrylamide; N,N-propyl (meth)acrylamide; N,N-dibutyl(meth)acrylamide; N,N-dihexyl(meth)acrylamide; N,N-dimethylaminomethylacrylamide; N,N-dimethylaminoethylacrylamide; N,N-dimethylaminopropylacrylamide; N,N-dimethylaminohexylacrylamide; N,N-diethylaminomethylacrylamide; N,N-diethylaminoethylacrylamide; N,N-diethylaminopropylacrylamide; N,N-dimethylaminohexylacrylamide; N-hydroxymethyl(meth)acrylamide; acrylamido-2-methylpropanesulfonate; and N,N'-methylenebisacrylamide.The inclusion of the radical of at least one amino(meth)acrylate monomer in the copolymer(s) (a1) is not excluded. As used herein, the term "amino(meth)acrylate" refers to a derivative of methacrylic acid or acrylic acid having a primary, secondary or tertiary amino group: the amino group may be part of a linear, branched or cyclic aliphatic group or an aromatic group. The at least one amino(meth)acrylate monomer may be a tertiary amino(meth)acrylate, such as in particular an N,N-dialkylaminoalkyl(meth)acrylate. In various embodiments, one or more of N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl methacrylate, or N,N-dimethylaminopropyl acrylate may be used.In a further non-limiting embodiment, the monomer mixture includes at least one vinyl monomer having a heterocyclic nitrogen structure. Exemplary heterocyclic structures are either 5- or 6-membered and may also comprise oxygen atoms in addition to nitrogen: the 5- or 6-membered ring may be, for example, a pyridine, pyrimidine, pyridazine, imidazoline, imidazole, oxazoline, oxazole or morpholine ring. Examples that can be used alone or in combination include: N-vinylcaprolactam (NVC); vinylmethyloxazolidinone (VMOX); N-vinylformamide; N-vinylcarbazole; N-vinylacetamide; and N-vinylpyrrolidone.Exemplary vinyl esters that can be copolymerized in the present disclosure include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and VEOVA™ series monomers available from Shell Chemical Company. Exemplary poly(meth)acrylates of alkane polyols that may be copolymerized include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, Butylenglycoldi(meth)acrylat Neopentylglycoldi(meth)acrylat Hexylenglycoldi(meth)acrylat trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Exemplary poly(meth)acrylates of oxyalkane polyols that can be copolymerized include diethylene glycol di(meth)acrylate, Dipropylenglykoldi(meth)acrylat triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, Dibutylenglykoldi(meth)acrylat di(pentamethylene glycol) dimethacrylate.In one embodiment, the monomer mixture comprises at least one monomer having the general formula AM1: R 4- C(H)=C(R 5)- A-(R 6 O) [a]- R 7( AM1) wherein: R 4 is H, methyl, CO 2 H or CH 2 CO 2 H; R 5 is hydrogen, halogen or methyl; A is -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH 2 C(O)N-, -C(O)N-, -CH 2-, - O-C(O)-, -NHC(O)O-, -NHC(O)NH-, -C 6 H 4( R 3)- NH-C(O)-O-, -C 6 H 4( R 8)- NH-C(O)-NH-, -C(O)O-CH 2- CH(CH 2 OH)-O-, -C(O)O-CH 2- CH(CH 2 OH)-NH-, -C(O)O-CH 2- CH 2- CH(OH)-O-, -C(O)O-CH 2- CH 2- CH(OH)-NH-, -CH 2- O-CH 2- CH(CH 2 OH)-O-, -CH 2- O-CH2-CH2-CH(OH)-O-, -CH 2- O-CH 2- CH(CH 2 OH)-NH- or -CH 2- O-CH 2- CH 2- CH(OH)-NH-; each R 6 independently represents C 2- C4-alkylene; [a] has a value of 5 to 100; R 7 represents C 1- C30-alkyl, C1-C30-hydroxyalkyl, C1-C30-aminoalkyl, C 3- C 18- cycloalkyl, C 2- C 5- heterocycloalkyl, C 2- C 20- alkenyl, C 2- C 12- alkynyl, C 6- C 18- aryl, C7-C24 alkaryl or C7-C24 aralkyl; and R 8 is -CH 2- or -(C)(CH 3)2-.Typical monomers according to formula AM1 are those wherein: R 4 is H, methyl, CO 2 H or CH 2 CO 2 H; R 5 is hydrogen, halogen or methyl; A is -CH 2 C(O)O- or -C(O)O-; each R 6 is independently C 2- C4alkylene; [a] has a value from 10 to 30; and R 7 is C 6- C 30- alkyl, C 6- C 30- hydroxyalkyl, C 6- C 30- aminoalkyl, C 3- C 18- cycloalkyl, C 6- C18aryl, C7-C18alkaryl or C7-C18aralkyl.Representative monomers according to formula AM1 are those wherein: R 4 is H, methyl, CO 2 H or CH 2 CO 2 H; R 5 is hydrogen, halogen or methyl; A is -C(O)O-; each R 6 is independently C 2- C3alkylene; [a] has a value of 10 to 30; and R 7 is C 6- C 30- alkyl, C 6- C 30- hydroxyalkyl or C 6- C 30- aminoalkyl.Exemplary monomers according to formula AM1, which may be copolymerized alone or in combination, include: Laurylethoxylat[a](meth)acrylat; Cetylethoxylat[a](meth)acrylat; Stearylethoxylat[a](meth)acrylat; Behenylethoxylat[a](meth)acrylat; Laurylethoxylat[a]itaconat; Cetylethoxylat[a]itaconat; Stearylethoxylat[a]itaconat; Behenylethoxylat[a]itaconat; lauryl ethoxylate [a] maleate; cetyl ethoxylate [a] maleate; stearyl ethoxylate [a] maleate; and Behenylethoxylat[a]maleat wherein [a] represents the number of moles of ethoxylation and has a value of 10 to 30. In other words, any of the above compounds can be described as an ethoxylated compound having a degree of ethoxylation of 10 to 30 moles of ethylene oxide. The parameter [a] may have a value of 15 to 30 or 15 to 25 in certain embodiments. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The hydroxy-functional (meth)acrylic copolymers are typically prepared by solution radical copolymerization, in which a solution of the monomers is produced in a solvent which is also capable of dissolving the copolymer, the monomers being polymerized by a radical polymerization, i.e. in the presence of the radical initiator. Generally, the above monomers are charged into a reflux reactor in the presence of at least one organic solvent and the radical initiator. The concentration of monomers in the solution may vary, but typically a weight ratio of monomer to solvent is from 1:20 to 2:1, for example from 1:2 to 1.5:1.Typically, conventional polymerization conditions are used which include a temperature in the range of from 25 to 250°C, e.g., from 50 to 250°C, or from 75 to 250°C. The polymerization pressure is generally not decisive, so that the polymerization can be carried out under reduced, atmospheric or superatmospheric pressure. The polymerization can be carried out, if necessary, with the exclusion of oxygen: the reaction vessel can be provided with an inert, dry gas jacket of, for example, nitrogen, helium and argon. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Usually, the at least one radical initiator is used in an amount of from 0.1 to 1% by weight, for example from 0.1 to 0.5% by weight, based on the total weight of the polymerizable monomers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.An exemplary class of suitable free radical initiators are organic peroxides, e.g., selected from: cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters, and peroxyketals.The radical initiator should be in the art. The radical initiator may be, for example, hydrogen peroxide. Alternatively, the radical initiator may also be an organic hydroperoxide. For completeness it should be noted that the definition of hydroperoxides also includes materials such as organic peroxides or organic polyesters which decompose or hydrolyse to form organic hydroperoxides in situ: examples of such peroxides and polyesters are cyclohexyl and hydroxycyclohexyl peroxide and t-butyl perbenzoate, respectively.In one embodiment of the disclosure, the radical initiator comprises at least one hydroperoxide compound represented by the following formula: R p OOH wherein: R p is an aliphatic or aromatic group containing up to 18 carbon atoms, and typically wherein: R p is C 1- C 12- alkyl, C 6- C 18- aryl, or C 7- C 18- aralkyl.The one or more radical initiators may include cumene hydroperoxide (CHP); para-menthane hydroperoxide; t-butyl hydroperoxide (TBH); t-butyl perbenzoate; t-butylperoxy pivalate; di-t-butyl peroxide; t-butylperoxy acetate; t-butylperoxy-2-hexanoate; t-amyl hydroperoxide; 1,2,3,4-tetramethylbutyl hydroperoxide; benzoyl peroxide; dibenzoyl peroxide; 1,3-bis(t-butylperoxy isopropyl)benzene; diacetyl peroxide; butyl 4,4-bis(t-butylperoxy)valerate; p-chlorobenzoyl peroxide; t-butylcumyl peroxide; di-t-butyl peroxide; dicumyl peroxide; 2,5-dimethyl-2,5-di-t-butylperoxy hexane; 2,5-Dimethyl-2,5-di-t-butyl peroxyhex-3-yn; and 4-methyl-2,2-di-t-butylperoxy pentane.Azo polymerization initiators may also be used and may be selected from: azo nitriles, azo esters, azo amides, azo amidines, azo imidazoline, macro azo initiators and combinations thereof.Examples of suitable azo polymerization initiators include: 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobis(isobutyronitrile); 2,2'-azobis(2,4-dimethylvaleronitrile); 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); 1,1'-azobis(cyclohexane-1-carbonitrile); 4,4'-azobis(4-cyanovaleric acid); dimethyl 2,2'-azobis(2-methylpropionate); 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide); 2,2'-azobis(N-butyl-2-methylpropionamide); 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride; 2,2'-azobis[2-(2-imidazolin-2-yl)propane] ; 2,2'-azobis(2-methylpropionamidine) dihydrochloride; 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate; 4,4-azobis(4-cyanovaleric acid), polymer with alpha,omega-bis(3-aminopropyl) polydimethyl siloxane (VPS-1001 available from Wako Pure Chemical Industries, Ltd.); and 4,4'-azobis(4-cyanopentanoic acid) polyethylene glycol polymer (VPE-0201 available from Wako Pure Chemical Industries, Ltd.).Redox initiators may also be used and include a combination of an oxidizing agent and a reducing agent. Suitable oxidizing agents may be selected from cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters, peroxyketals, and mixtures thereof. The corresponding reducing agent can be selected from: alkali metal sulfites, alkali metal hydrogen sulfites, alkali metal metabisulfites, formaldehyde sulfoxylates, alkali metal salts of aliphatic sulfinic acids, alkali metal hydrogen sulfides; salts of polyvalent metals, in particular Co(II) salts and Fe(II) salts such as iron(II) sulfate, iron(II) ammonium sulfate or iron(II) phosphate; dihydroxmaleic acid; benzoin; ascorbic acid; reducing saccharides such as sorbose, glucose, fructose and / or dihydroxyacetone; and mixtures thereof.The free radical polymerization can be carried out in the presence of chain transfer agents which transfer the free radicals and reduce the molecular weight of the polymer obtained and / or control the chain growth in the polymerization. When added, the chain transfer agent may comprise between 0.01 and 1% by weight of the mixture based on the total weight of the polymerizable monomers. The amount of the polymerization initiator and the chain transfer agents present contributes to the number average molecular weight of the (co)polymer, although the choice of the solvent may also play a role. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The radical polymerization reactions are typically carried out in an organic solvent, typically a polar solvent. Effective polar solvents may have a boiling point of at least 20°C, e.g. at least 30°C or at least 40°C, measured at a pressure of 1 atmosphere (1.01325 bar). Examples of such polar solvents, which may be used alone or in combination, include: C 1- C 8- alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and isobutanol; acetonitrile; N,N-di(C 1- C 4)- alkylacylamides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); hexamethylphosphoramide; N-methylpyrrolidone; pyridine; Esters such as (C 1- C 8) alkyl acetates, ethoxydiglycol acetate, dimethyl glutamate, dimethyl maleate, dipropyl oxalate, ethyl lactate, benzyl benzoate, butyl octyl benzoate and ethylhexyl benzoate; ketones such as acetone, ethyl ketone, methyl ethyl ketone (2-butanone) and methyl isobutyl ketone; ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF) and 1,2-dimethoxyethane; 1,3-dioxolane; dimethyl sulfoxide (DMSO) and dichloromethane (DCM). In an exemplary embodiment, the polymerization reaction is carried out in the presence of a (C 1- C 8) alkyl acetate, such as ethyl acetate.The hydroxyl functional (meth)acrylate copolymer (a1) can be prepared from the monomer mixture by a skew feed polymerization process with at least two monomer feed streams. In one embodiment, the first feed stream comprises: I) 60 to 100 wt % of the hydroxyl functional adduct of a mono-epoxy ester and an unsaturated carboxylic acid, based on the total weight of monomers of component i) in the monomer mixture; II) 0 to 60 wt % of the hydroxyl functional unsaturated monomer ii), based on the total weight of monomer of component ii) in the monomer mixture; III) 0 to 30 wt % of the unsaturated acid functional monomer iii), based on the total weight of monomer of component iii) in the monomer mixture; and VI) 0 to 80 wt % of the other polymerizable unsaturated monomers iv), based on the total weight of monomers of component vi) in the monomer mixture. The remaining one or more feed streams comprise the remainder of monomer components i) through iv). In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In such skew feed polymerization, the total amount of the radical initiator to be supplied may be fully added at the beginning of the first supplying step. However, it is typical that fractions of the radical initiator are added over time and, in particular, that a fraction is added to each feed stream. Each initiator fraction fed to a particular reflux reactor feed stream may be fed either as a single dose, stepwise or continuously.Similarly, the total amount of the organic solvent may be fully supplied at the beginning of the first supplying step. However, it is typical that fractions of the organic solvent are added over time and, in particular, that a fraction is added to each feed stream. Usually, a solvent fraction determined for a particular feed stream may be added to the reflux reactor before or simultaneously with the beginning of monomer addition.In certain skew feed polymerization embodiments, the reactor contents can be rinsed with an organic solvent after addition of the first feed stream. An intermediate rinsing step can be carried out similarly between each subsequent feeding step.Progress of the polymerization reaction and optionally each of its charging steps may be monitored by potentiometric titration to determine the hydroxyl number and / or acid number. When these numbers reach a certain level based on a desired level of conversion, the reactor contents are typically cooled and then partially or fully neutralized by addition of the appropriate amount of base. The reactor contents comprising the hydroxyl functional (meth)acrylate copolymer (a1) can then be converted to an aqueous dispersion by normal dilution or reverse dilution with water.Component (a2)The binder portion a) of the two-part (2k) composition of the present disclosure comprises (a2) at least one non-aromatic polyester having active hydrogen groups, the non-aromatic polyester having: a number average molecular weight (Mn) of about 500 to about 5000 daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 100 to about 600 mg KOH / g; and a calculated hydroxyl functionality of about 2 to about 8. In various non-limiting embodiments, all values and value ranges, including and between the above, are expressly intended for use herein.In important embodiments, the non-aromatic polyester (a2) has: a number average molecular weight (Mn) of about 500 to about 1500 daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of about 4 to about 8.It is typical that the weight ratio of the solids of component (a1), hydroxyl functional (meth)acrylate copolymer(s), to the solids of component (a2), polyester(s) is from about 100:1 to about 100:35, such as from about 100:5 to about 100:25, from about 100:5 to about 100:20, or from about 100:5 to about 100:15. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.For non-aromatic polyesters, it is typical to be prepared by polycondensation: at least one hydroxyl functional component (a2h); at least one carboxyl functional component (a2c); and optionally at least one hydroxycarboxylic acid component (a2hc). These components can be selected in terms of type and amount in such a way that the values mentioned above for molecular weight, acid number, hydroxyl number and functionality are obtained for the nonaromatic polyester. In general, the polycondensation reaction can be exemplified by a stoichiometric excess of hydroxyl groups to carboxyl groups. Typically, the stoichiometric excess of hydroxyl groups to carboxyl groups may be between 5 and 40 mol %, for example between 5 and 35 mol %, between 5 and 30 mol % or between 5 and 25 mol %. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The hydroxyl functional component (a2h) may comprise, based on the weight of the hydroxyl functional component: 75 to 100 wt%, for example 80 to 100 wt%, or 90 to 100 wt%, of at least one polyol having 3 to 6 hydroxyl groups; and 0 to 25 wt%, for example 0 to 20 wt%, or 0 to 10 wt%, of at least one diol. In certain embodiments, the hydroxyl functional component (a2h) may comprise, based on the weight of the hydroxyl functional component: 95 to 100 wt % of at least one polyol having 3 to 6 hydroxyl groups; and 0 to 5 wt % of at least one diol. In other embodiments, the hydroxyl-functional component (a2h) consists essentially of or consists of the at least one polyol having 3 to 6 hydroxyl groups. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Suitable polyols having 3 to 6 hydroxyl groups may be saturated or unsaturated and may be aliphatic or cycloaliphatic compounds: the compounds may typically have a molecular weight of 400 daltons or less. Non-limiting examples of aliphatic triols include: 1,2,3-propanetriol; 1,2,4-butanetriol; 2-ethyl-2-hydroxymethyl-1,3-propanediol (trimethylolpropane), 3-methyl-1,3,5-pentanetriol; 1,2,3-hexanetriol; 1,2,6-hexanetriol; 2,5-dimethyl-1,2,6-hexanetriol; 1,2,3-heptanetriol; 1,2,3-octanetriol; and 2-hydroxymethyl-1,3-propanediol. Non-limiting examples of aliphatic tetrols and aliphatic pentols include: 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol); pentose; pentopyranose; 6-deoxyhexopyranose; 2,5-anhydrohexitol; 1,5-anhydrohexitol; 6-deoxyhexose; 1-deoxyhexitol; and pentitol. An exemplary six hydroxyl polyol is D-glucitol (sorbitol). In embodiments, 2-ethyl-2-hydroxymethyl-1,3-propanediol (trimethylolpropane), 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol), or mixtures thereof may also be used.The present disclosure does not exclude the use of (C 2- C 4)- alkylene oxide adducts of the aforementioned diols, triols and higher polyols as polyol reactants having 3 to 6 hydroxyl groups.Suitable diols for use in the hydroxyl functional component can be saturated or unsaturated and aliphatic or cycloaliphatic dihydroxy compounds. The reactive diols typically have a molecular weight of 250 daltons or less. When the term "diol" is used herein, it may include equivalent ester-forming derivatives thereof, provided, however, that the molecular weight requirement refers only to the diol and not to its derivative. Exemplary ester-forming derivatives are the acetates of the diols and, for example, ethylene oxide or ethylene carbonate for ethylene glycol.Typical diols are those having 2 to 10 carbon atoms. Examples of these diols include: ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methylpropanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol, hexanediol, decanediol, hexamethylene glycol; cyclohexanedimethanol; and polyoxyalkylene glycols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol and tetrapropylene glycol. Mixtures of such diols may also be used.The carboxyl functional component (a2c) may comprise, based on the weight of the carboxyl functional component: 75 to 100 wt%, such as 80 to 100 wt%, or 90 to 100 wt%, of at least one dicarboxylic acid; and 0 to 25 wt%, such as 0 to 20 wt%, or 0 to 10 wt%, of at least one monocarboxylic acid. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Dicarboxylic acids suitable for use herein include aliphatic and / or cycloaliphatic dicarboxylic acids. The dicarboxylic acids may typically have a molecular weight of less than 600 daltons. As used herein, the term "dicarboxylic acids" includes equivalents of dicarboxylic acids having two carboxyl functional groups that substantially behave like dicarboxylic acids upon reaction with polyols to form polyesters. These equivalents include esters and ester-forming reactive derivatives such as acid halides and anhydrides, provided however that the above molecular weight range refers to the acid and not to its equivalent ester or ester-forming derivatives. Thus, included are an ester of a dicarboxylic acid having a molecular weight greater than 300 daltons or an acid equivalent of a dicarboxylic acid having a molecular weight greater than 300 daltons, provided the acid has a molecular weight less than 300 daltons. Moreover, the dicarboxylic acids may contain any substituent groups or combinations that do not substantially interfere with polymer formation and use of the polymer of this disclosure.Typical dicarboxylic acids include those selected from: hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, and alkyldicarboxylic acids having a total of 2 to 16 carbon atoms. Representative alkyl dicarboxylic acids include: glutaric acid, adipic acid, pimelic acid, succinic acid, sebacic acid, azelaic acid, and malonic acid. Adipic acid can be used, for example.Dimer fatty acids can be used as dicarboxylic acid reactants for the polyester synthesis reaction described above. Exemplary dimer fatty acids include C 36- to C 44- aliphatic diacid which can be prepared by oxidative coupling of C 18- to C 22- unsaturated monoacids. Dimer acids derived from the oxidative coupling of oleic acid, linoleic acid or tall oil fatty acid can be used. However, in embodiments where at least one dimer fatty acid is used in the reaction, it is typical that at least one non-dimerized dicarboxylic acid is present. In particular, if at least one dimer fatty acid is used, the dimer fatty acid can be reacted in an amount of from 5 to 50% by weight, typically from 5 to 40% by weight, from 5 to 30% by weight or from 5 to 25% by weight, based on the total weight of the carboxyl-functional component. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Monocarboxylic acids suitable as reactants for the polycondensation reaction include aliphatic and / or cycloaliphatic monocarboxylic acids. The monocarboxylic acids may typically have a molecular weight of less than 300 daltons. Exemplary monocarboxylic acids that may be used alone or in combination include: formic acid, acetic acid, propionic acid, n-butanoic acid, butanoic acid, 2-ethylhexanoic acid, octanoic acid, isononanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, palmitic acid, and stearic acid.A (cyclo)aliphatic hydroxycarboxylic acid component (a2hc) may optionally participate in the polycondensation reaction that gives the non-aromatic polyester polyol (a2). When present, it is typical that the total amount of hydroxycarboxylic acid is at most 10 wt.%, based on the total weight of the reactant compounds (a2h, a2c and a2hc). Examples of hydroxycarboxylic acids include: 12-hydroxystearic acid, 6-hydroxyhexanoic acid, citric acid, tartaric acid and dimethylolpropionic acid. Instead of the monohydroxycarboxylic acids, the corresponding lactones can also be used as reactants.It is typical herein that the reaction mixture for the above polycondensation reaction is substantially free of solvents. In addition, the starting reaction mixture may be substantially free of added water. However, when the reaction is carried out in solution, suitable solvents may be non-reactive, substantially anhydrous, organic liquids capable of dissolving at least 1% and typically more than 10% by weight of the polyester products at 25°C. Suitable organic solvents which can be used alone or in combination include: aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as heptane and decane; alicyclic hydrocarbons such as cyclohexane and decalin; chlorinated hydrocarbons such as chloroform and trichloroethylene; esters such as ethyl acetate and methyl butyrate; and ethers such as tetrahydrofuran (THF) and dioxane.The polycondensation reaction may be carried out in the presence of a suitable catalyst. Common catalysts include acid catalysts and organometallic catalysts, with titanium, zirconium and tin alkoxides, carboxylates and chelates being examples of the latter. Typically, the catalyst is a titanium alkoxide, titanium carboxylate or titanium chelate catalyst.Exemplary titanium alkoxides include: tetramethyl titanates; tetraethyl titanates; tetrapropyl titanates; tetraisopropyl titanates; tetrabutyl titanates; tetrapentyl titanates; tetrahexyl titanates; tetraoctyl titanates; tetranonyl titanates; tetradodecyl titanates; tetradecyl titanates; tetraoctadecyl titanates; tetradecyl titanates; tetraheptyl titanates; and mixtures thereof. The tin or zirconium counterparts of the above-mentioned alcoholates can be used in part as catalysts.It is typical that the catalyst is used in an amount of from 0.1 to 5 wt%, for example from 0.1 to 2.0 wt%, from 0.1 to 1.5 wt%, or from 0.1 to 1.0 wt%, based on the total weight of the reactants (a2h, a2c and a2hc). In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The polycondensation reaction can also be carried out in the presence of at least one stabilizer. Typical stabilizers - usually present in an amount of 0.01 to 5 wt.%, based on the total weight of reactants (a2h, a2c and a2hc) - may be: hydroquinone and its alkylated derivatives; phenolic compounds having electron withdrawing substituents; and quinoid compounds. Specific examples of such stabilizing compounds, which may be used alone or in combination, include: 2,3-dichloro-1,4-naphthoquinone; 2,3-dibromo-1,4-naphthoquinone; 2,3-dicyano-1,4-naphthoquinone; 2-chloro-1,4-naphthoquinone; 2-bromo-1,4-naphthoquinone; 2-nitro-1,4-naphthoquinone; 2,3,6,7,8,9-hexachloro-1,4-naphthoquinone; 3-bromo-2-chloro-1,4-naphthoquinone; 1,4-hydroquinone; 4-tertiarybutyl catechol; 4-methoxyphenol; methylhydroquinone; 4-chloro-2-nitrophenol; 2,4-dinitroparacresol; 2,4-dinitrophenol; and phenothiazine. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.If a stabilizer is used in the polycondensation reaction, one or more known electron donors forming electron donor-acceptor complexes may also be added to the mixture of reactants. Typical electron donors - which would usually total 0.01 to 1% by weight based on the total weight of reactants (a2h, a2c and a2hc) - include: 1-methylimidazole; 2-methylimidazole; 2-ethyl-4-methylimidazole; 2-heptadecylimidazole; 2-isopropylimidazole; 2-(2-ethyl-4-methylimidazyl)-1-cyanoethane; and 2-undecylimidazole. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In the synthesis of the polyesters, the reactants, catalyst(s) and any stabilizers and electron donors used are typically placed in a suitable reaction vessel with a distillation apparatus. This vessel is typically dried and flushed with an inert gas such as nitrogen or argon before it is filled and this inert gas atmosphere can be maintained in the vessel during the reaction. The temperature of the vessel is typically adjusted based on the lowest boiling point of the reactants, i.e., usually an alcohol. In various embodiments, a temperature of from about 125 to about 300° C., or from about 125 to about 275° C. may be considered a standard. For an initial period, the vessel may be maintained at atmospheric pressure, but once water distillation is no longer observed, at least a partial vacuum may be applied to the vessel to complete the polycondensation reaction. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The reaction can be monitored by analysis of the acid number (Av) of the reactant mixture over time and the reaction is typically stopped when the acid number determined reaches a value of less than about 10 mg KOH / g, or ideally less than about 5 mg KOH / g, or even less than about 1 mg KOH / g. The time to reach this point depends on various factors, such as temperature, catalyst type and reactants used: however, in general it is between about 0.5 and about 20 hours, for example between about 1 and about 8 hours or between about 2 and about 6 hours. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The polyester synthesized by the polycondensation reaction can be separated and purified by known methods such as filtration, extraction, evaporation, distillation or chromatography.Non-polymeric polyol (a4), (a5)The addition of certain non-polymeric low molecular weight polyols to part a) of the composition can improve the moisture resistance of the coatings obtained from the compositions and promote easier mixing between the two parts of the composition. Any improvement in such blending can be reflected in better applicability of the coating compositions and an improved appearance of the coatings obtained therefrom.In one embodiment, the binder portion a) of the two-part (2K) composition may further comprise: (a3) at least one non-polymeric acyclic polyol having a weight average molecular weight (Mw) of less than about 300 daltons and a water solubility at about 20°C of less than about 6 g / 100 mL of water. For example, the (a3) at least one non-polymeric acyclic polyol may be present in the binder part a) in an amount of 0 to 10 wt %, based on the weight of the binder part a). In certain embodiments, the (a3), at least one non-polymeric acyclic polyol may be present in binder portion a) in a fraction of the amount of component (a1). For example, the binder part a) may comprise 0 to 10 wt %, 0 to 8 wt %, 0 to 5 wt % or 0 to 3 wt % (a3) of the at least one non-polymeric acyclic polyol, based on the weight of component (a1). In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary non-polymeric acyclic polyols that may be used alone or in combination include: 2-ethylhexane-1,3-diol; and 2-butyl-2-ethyl-1,3-propanediol.In another embodiment that is not mutually exclusive with the above, the binder part a) of the two-part (2K) composition may further comprise: (a4) at least one non-polymeric cycloaliphatic polyol having a weight average molecular weight (Mw) of less than about 300 daltons. For example, the (a4) at least one non-polymeric cycloaliphatic polyol may be present in the binder part a) in an amount of 0 to 10 wt.%, based on the weight of the binder part a). In certain embodiments, the (a4) at least one non-polymeric cycloaliphatic polyol may be contained in the binder portion a) in a fraction of the amount of component (a1). For example, the binder part a) may comprise 0 to 10 wt %, 0 to 8 wt %, 0 to 5 wt % or 0 to 3 wt % (a4) of at least one non-polymeric cycloaliphatic polyol, based on the weight of component (a1). In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary non-polymeric cycloaliphatic polyols that may be used alone or in combination include: 1,4-cyclohexanedimethanol; 1,3-cyclohexanedimethanol; 1,2-cyclohexanedimethanol; 1,4-cyclohexanedimethanol; 2,2-bis(4-hydroxycyclohexyl)propane; dianhydro-D-glucitol (isosorbide); and 4,8-bis(hydroxymethyl)tricyclo[5.2.1.0 2,6] decane. In one embodiment, the at least one non-polymeric cycloaliphatic polyol comprises 1,4-cyclohexanedimethanol.Part b) Cross-linkerCrosslinker portion b) of the present composition comprises at least one polyisocyanate compound having pendant -NCO groups. It is not excluded that the cross-linking part b) of the composition may comprise further cross-linking compounds, such as melamine resins and blocked isocyanates, in addition to the polyisocyanate compound(s) having pendant NCO groups.The molar ratio of active hydrogen atoms to -NCO groups in the two-part (2K) composition is between about 5:1 and about 1:5, typically between about 3:1 and about 1:3. The term "-NCO groups" includes blocked -NCO groups, which are therefore included in the term molar ratio. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The term "polyisocyanate" denotes a compound having at least two functional -N=C=O groups, for example 2 to 5 or 2 to 4 functional -N=C=O groups. Suitable polyisocyanates are aliphatic, cycloaliphatic, aromatic and heterocyclic isocyanates, dimers and trimers thereof, and mixtures thereof.Aliphatic and cycloaliphatic polyisocyanates may contain 6 to 100 carbon atoms, which are connected in a straight chain or cyclic manner and have at least two reactive isocyanate groups. Examples of suitable aliphatic isocyanates are straight-chain isocyanates such as ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, triisocyantenonane, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, bis(isocyanatoethyl) carbonate and bis(isocyanatoethyl) ether. Exemplary cycloaliphatic polyisocyanates include dicyclohexylmethane 4,4'-diisocyanate (H 12 MDI), 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), cyclohexane-1,4-diisocyanate, hydrogenated xylylene diisocyanate (H 6 XDI), 1-methyl-2,4-diisocyanatocyclohexane, m- or p-tetramethylxylene diisocyanate (m-TMXDI, p-TMXDI), and dimer fatty acid diisocyanate. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The term "aromatic polyisocyanate" is used herein to describe organic isocyanates in which the isocyanate groups are directly bonded to the ring(s) of a mono- or polynuclear aromatic hydrocarbon group. A mono- or polynuclear aromatic hydrocarbon group is in turn to be understood as a substantially planar cyclic hydrocarbon unit with conjugated double bonds, which can consist of a single ring or can comprise a plurality of fused (fused) or covalently bonded rings. The term aromatic includes alkylaryl. Typically, the hydrocarbon (main) chain contains 5, 6, 7 or 8 main chain atoms in one cycle. Examples of such planar cyclic hydrocarbon radicals are cyclopentadienyl, phenyl, napthaenyl-,

[10] annulenenyl-(1,3,5,7,9-cyclodecapentaenyl-),

[12] annulenenyl-, [8]annulenenyl-, phenalin (perinaphthene), 1,9-dihydropyrene, chrysene (1,2-benzophenanthrene). Examples of alkylaryl units are benzyl, phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-naphthylpropyl, 2-naphthylpropyl, 3-naphthylpropyl and 3-naphthylbutyl.Exemplary aromatic polyisocyanates include: all isomers of toluene diisocyanate (TDI), either in isomerically pure form or as a mixture of several isomers; naphthalene 1,5-diisocyanate; diphenylmethane 4,4'-diisocyanate (MDI); diphenylmethane 2,4'-diisocyanate and mixtures of diphenylmethane 4,4'-diisocyanate with the 2,4'-isomer or mixtures thereof with oligomers of higher functionality (so-called crude MDI); xylylene diisocyanate (XDI); diphenyldimethylmethane 4,4'-diisocyanate; di- and tetraalkyl diphenylmethane diisocyanates; dibenzyl 4,4'-diisocyanate; phenylene 1,3-diisocyanate; phenylene 1,4-diisocyanate; triphenylmethane triisocyanate, 1,3,5-benzene triisocyanate and 2,4,6-toluene triisocyanate.When used, the polyisocyanates may have been biuretized, allophanated and / or isocyanurated by well known methods. In use, such derivatives may be substantially free of parent diisocyanate: the derivatives may have been separated from excess parent diisocyanate by conventional means including, but not limited to, distillation.It is also noted that the term "polyisocyanate" includes hydrophilic prepolymers formed by the partial reaction of the above aliphatic, cycloaliphatic, aromatic and heterocyclic isocyanates with polyether polyols or polyester polyols to obtain isocyanate functional oligomers which can be used alone or in combination with free isocyanates.The term "polyisocyanate" further includes ionically modified isocyanate-functional compounds, e.g., ionically modified isocyanate-functional prepolymers. The ionically modified polyisocyanates contain at least two isocyanate groups and at least one ionic or ionogenic group. In certain embodiments, anionically modified, isocyanate-functional compounds, such as anionically modified, isocyanate-functional prepolymers, can be incorporated into the crosslinking part b). Suitable anionic or anionic groups in this context are carboxylic acid groups, sulfonic acid groups, phosphonic acid groups and salts thereof. Suitable bases that can neutralize the anionic groups to form such salts include: alkali metals such as Na and K; ammonium; and trialkylamines such as triethylamine and triisopropylamine.Exemplary polyisocyanates commercially available from Covestro AG that may be used in the present disclosure include: Desmodur® N3900; Bayhydur® Ultra 2487 / 1; Bayhydur®Ultra 2700; Bayhydur® Ultra 3100; Bayhydur®Ultra 304; Bayhydur®Ultra 305; Bayhydur®Ultra 307; Bayhydur® XP 2451 / 1; Bayhydur® XP 2547; Bayhydur® XP 2655; Bayhydur® XP 2759; Bayhydur® 2858 XP; Bayhydur® Eco 701-90; Bayhydur® 401-60 PGDA and Bayhydur® 401-70 MPA / X.Additives and Supplementary IngredientsThe compositions of the present disclosure may further contain or be free of one or more adjuvants and additives that may impart improved properties to these compositions and coatings obtained therefrom. For example, the adjuvants and additives may impart one or more of the following properties: reduced dullness; improved sharpness of image (DOI); longer allowed processing time; faster cure time; lower residual tack; and improved flow. Such auxiliaries and additives include: catalysts, plasticizers, stabilizers including UV stabilizers, reactive diluents, desiccants or moisture scavengers, adhesion promoters, wetting agents, defoamers, flame retardants, rheology control agents, color pigments, dyes, effect pigments, cosolvents and non-reactive diluents.Such adjuvants and additives may be used in any combination and in any proportions so long as they do not impair the nature and essential properties of the composition. Although there may be exceptions in some cases, these adjuvants and additives typically make up a total of between 0 and 40 wt%, for example between 0 and 30 wt%, of the total composition.Generally, additives and adjuvants containing reactive groups may be mixed into the corresponding part of a two part (2K) composition to ensure their shelf stability; non-reactives may be formulated into either part or both parts. For example, in certain embodiments, crosslinker portion b) of the composition may be free of compounds having active hydrogen atoms.The compositions may comprise one or more catalysts for the reaction of -NCO groups with active hydrogen compounds. Standard catalysts known in the art include: tin(II) salts of carboxylic acids such as tin(II) octoate, tin(II) oleate, tin(II) acetate and tin(II) laureate; dialkyl tin dicarboxylates such as dibutyltin dilaurate and dibutyltin diacetate; tertiary amines; alkanolamine compounds; 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammonium hydroxides; alkali metal hydroxides; alkali metal alkoxides; tin alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide and dibutyltin diisoproxide; tin oxides such as dibutyltin oxide and dioctyltin oxide; the reaction products of dibutyltin oxides and phthalic esters; tin mercaptides; alkyl titanates; Organoaluminium compounds such as aluminium trisacetylacetonate, aluminium triethylacetoacetate and Diisopropoxyaluminiumethylacetoacetat ; chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; organosilicon titanium compounds; bismuth tris-2-ethylhexanoate; acidic compounds such as phosphoric acid and p-toluenesulfonic acid; triphenylborane; triphenylphosphine; 1,8-diazabicycloundec-7-ene (DBU); 1,5-diazabicyclo[4.3.0]non-5-ene; 1,4-diazabicyclo[2.2.2]octane; 4-dimethylaminopyridine; 1,5,7-triazabicyclo[4.4.0]dec-5-ene; 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; 1,8-bis(tetramethylguanidano)naphthalene; and 2-tert-butyl-1,1,3,3-tetramethylguanidine.Depending on the nature of the isocyanate, the amount of catalyst used is typically between 0.005 and 2% by weight of the composition. For example, the composition may comprise from 0.01 to 2% or from 0.01 to 1% by weight of catalyst based on the weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The addition of certain additives can promote adhesion of the coating compositions to certain substrates. In this connection, the composition may comprise 0 to 5 wt%, for example 0.5 to 5 wt%, based on the weight of the composition, of at least one additive selected from: morin (2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-cumarone-4-ketone); 3,7-dihydroxy-2-naphthoic acid (3,7-dihydroxy-naphthene-2-carboxylic acid); pyrogallol carboxylic acid (2,3,4-trihydroxybenzoic acid), 3,4-dihydroxybenzeneguanidine acetic acid; gallic acid (3,4,5-trihydroxybenzoic acid); para-aminosalicylic acid (4-amino-2-hydroxybenzoic acid, PAS); flutter carboxylic acid (4,4'-methylenebis(3-hydroxy-2-naphthoic acid)); citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid); and mixtures thereof. In certain embodiments, citric acid, gallic acid, or para-aminosalicylic acid (PAS) may be used alone or in combination.The term "pigment" as used herein refers to a molecule which is insoluble in the liquid carrier and imparts either a color or an optical effect thereto.The composition may comprise at least one color pigment in certain embodiments. Color pigments useful herein may be organic or inorganic. Exemplary color pigments that can be used alone or in combination include: azo pigments; anthraquinone pigments; benzimidazolone pigments; isoindoline pigments; naphthol pigments such as naphthol red; nitroso pigments; perinone pigments; perylene pigments; polycyclic pigments; pyrropyrrole pigments; pthalocyanins such as copper phthalocyanine blue and copper phthalocyanine green; quinacridones such as quinacridone violet; quinophthalone pigments; dioxazine pigments; carbon black; anazurin; aluminum silicate; aluminum potassium silicate; antimony oxide; barium metaborate; barium sulfate; cadmium sulfide; cadmium selenide; calcium carbonate; calcium metaborate; calcium metasilicate; chromium oxides; clay; copper oxides; copper oxychloride; feldspar; Iron oxides such as yellow and red iron oxides; kaolinite; lithopone; magnesium silicates; nepheline syenite; silicates; sulfides; talc; titanium dioxide; ultramarine; zinc chromate; zinc oxide; and zinc phosphate.The composition may in certain embodiments contain at least one effect pigment, i.e. a pigment that exhibits optical effects that are not caused by absorption. Particular examples are graphite effect pigments, metal effect pigments and pearlescent pigments. The effect pigments may have at least one of the following features: a specific surface area of from about 1 to about 60 m 2 / g, e.g., from about 5 to about 50 m 2 / g, as determined using nitrogen absorption according to the Brunauer-Emmett-Teller (BET) method; and a median volume particle size (Dv50) of from about 1 to about 500 μm, e.g., from about 5 to about 100 μm, as determined by laser diffraction. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The metallic effect pigments may contain acicular, spherical, ellipsoidal, cylindrical, pearlescent, cubic, flake or flake particles. Particles of different forms may be used alone or in combination.Exemplary metals that may include metallic effect pigments include: aluminum, copper, copper-zinc alloys, copper-tin alloys, stainless steel, carbon steel, iron, silver, zinc, nickel, titanium, chromium, manganese, vanadium, magnesium, and zinc-magnesium alloys. The metal component may be coated with one or more inert oxides to form the effect pigment. Exemplary metal oxides include: silica, titanium dioxide, zinc oxide, zirconia, tin oxide, ceria, vanadium oxide, manganese oxide, lead oxide, chromium oxide, iron oxide, alumina and tungsten oxide. When present in the pigment, the thickness of such metal oxide layers is typically 20 to 400 nm, e.g., 50 to 400 nm or 50 to 250 nm. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Pearlescent pigments consist of a transparent, nonmetallic, platelet-shaped substrate which is coated with at least one layer of metal oxides having different refractive indices. In some embodiments, multiple layers of metal oxides are used, with a difference of at least about 0.1 in the refractive indices of the successive layers. In some embodiments, the pearlescent pigment has an interference color when viewed over a black background.Exemplary nonmetallic platelet substrates include: natural mica, synthetic mica, bismuth oxychloride, graphite, alumina, iron mica, perlite, silica, borosilicate glass, glass, titanium dioxide-coated mica, and iron oxide-coated mica.Exemplary metal oxides from which the one or more coating layers of the pearlescent pigments may be formed include: silicon dioxide, titanium dioxide, zinc oxide, zirconium dioxide, tin oxide, cerium dioxide, vanadium oxide, manganese oxide, lead oxide, chromium oxide, iron oxide, aluminum oxide and tungsten oxide. The thickness of each metal oxide layer of the pearlescent pigment can be determined independently, but is usually between about 20 and about 400 nm, for example between 50 and 400 nm or between 50 and 250 nm. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The rheology control agent, which may optionally be useful in the present composition, may comprise fillers, thickeners, and combinations thereof. The total amount of rheology control agent in the composition does not normally exceed 10% by weight based on the weight of the composition. The composition may, for example, comprise 0 to 8% by weight, 0 to 5% by weight or 0 to 2% by weight rheology control agent based on the weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary thickeners include: clay-based thickeners such as organoclays; polysaccharides such as guar and xanthan; polyacrylates; and associative thickeners. The following cellulose or cellulose derivatives can be used in particular as polysaccharide thickeners: carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, cellulose nanofibers and cellulose nanocrystals.The filler may contain acicular, spherical, ellipsoidal, cylindrical, spherical, cubic or plate-shaped particles, which may be used singly or in combination. Moreover, agglomerates of more than one type of particle may also be used. The fillers typically have a median volume particle size (Dv50), measured by laser diffraction, of from about 0.1 to about 1500 μm, for example from about 1 to about 1250 μm. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Exemplary fillers include calcium carbonate, calcium oxide, calcium hydroxide (powdered lime), precipitated and / or fumed silica, zeolites, bentonites, wollastonite, magnesium carbonate, diatomaceous earth, barium sulfate, aluminum oxide, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, limestone, mica, glass beads, glass powder, and other milled mineral materials. Organic fillers can also be used, in particular wood fibers, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, comminuted straw, chopped material, ground walnut shells and other comminuted fibers. Short fibers such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers, or polyethylene fibers may also be added.When present, fumed and / or precipitated silica can have a BET specific surface area of from about 10 to about 90 m 2 / g. When such silica(s) are / are used, they may not result in an additional increase in the viscosity of the composition, but may contribute to the strengthening of the cured composition. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.It is likewise conceivable to use pyrogenic and / or precipitated silica having a higher specific BET surface area, advantageously from about 100 to about 250 m 2 / g, as filler: owing to the larger BET surface area, the effect of reinforcing the cured composition is achieved with a lower proportion by weight of silica. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Hollow spheres with a mineral shell or a plastic shell can also be used. These may be, for example, hollow glass spheres which are commercially available under the trade name Glass Bubbles®. Plastic-based hollow spheres, such as Expancel® or Dualite® can also be used. They may contain, for example, inorganic or organic substances and each have a volume-based median particle size (Dv50) of 1 mm or less, typically 500 μm or less, as determined by laser diffraction.Fillers which impart thixotropy to the composition may be typical for many applications. Such fillers are also referred to as rheological auxiliaries and include, for example, hydrogenated castor oil, fatty acid amides and swellable plastics such as PVC.A "plasticizer" in the sense of this disclosure is a substance which reduces the viscosity of the composition and thus facilitates its processability. The plasticizer may constitute up to 10% or up to 5% by weight, based on the total weight of the composition, and is typically selected from: diurethanes; ethers of monofunctional, linear or branched C4-C16alcohols such as Cetiol OE (available from BASF); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic esters and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic esters; esters of OH group-bearing or epoxidized fatty acids; glycolic acid esters; benzoic esters; phosphoric esters; sulfonic esters; trimellitic acid esters; polyether plasticizers such as end-capped polyethylene or polypropylene glycols; polystyrene; hydrocarbon plasticizers; chloroparaffin; and mixtures thereof. It is pointed out that phthalic acid esters can in principle be used as plasticizers, which, however, are not customary because of their toxicological potential.For the purposes of this disclosure, "stabilizers" are antioxidants, thermal stabilizers or hydrolysis stabilizers. The stabilizers may constitute in total up to 10% by weight or up to 5% by weight, based on the total weight of the composition. Commercial examples of stabilizers that may be used herein include: hindered phenols, thioethers, benzotriazoles, benzophenones, benzoates, cyanoacrylates, acrylates, hindered amine light stabilizer (HALS) type amines, phosphorus, sulfur, and mixtures thereof.To extend durability even further, it is often advisable to further stabilize the compositions of the present disclosure against moisture ingress by the use of desiccants. Examples of suitable drying agents or moisture scavengers include: silica gel, anhydrous calcium sulfate (anhydrite), calcium sulfate dihydrate (gypsum), calcium oxide, montmorillonite clay, molecular sieves such as natural or synthetic zeolite, and activated alumina.Waxes useful in the present disclosure may have a softening point of about 50 to about 150° C. and may include one or more of the following: polyethylene having a number average molecular weight (Mn) of about 500 to about 7500; petroleum waxes such as paraffin wax and microcrystalline wax; synthetic waxes prepared by polymerization of carbon monoxide and hydrogen, such as Fischer-Tropsch wax; polyolefin waxes including functionalized polyolefin waxes, of which maleated polyethylene, maleated polypropylene and maleated poly(ethylene-co-propylene) may be mentioned as examples; and hydrogenated animal, fish or vegetable oils. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Occasionally, there is also a need to reduce the viscosity of the composition according to the present disclosure for certain applications through the use of reactive diluent(s). The total amount of reactive diluents present is typically between 0 and 10 wt %, for example between 0 and 5 wt %, based on the total weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The presence of cosolvents and non-reactive diluents in the compositions of the present disclosure is also not excluded if it can usefully reduce the viscosity of the compositions. For example, but by way of illustration only, the compositions may contain one or more of the following: alkyl acetate solvents such as ethyl acetate, n-propyl acetate, butyl acetate, n-butyl acetate, propylene glycol monomethyl ether acetate, and methoxy propyl acetate (MPA); alkyl propionate solvents such as n-butyl propionate and n-pentyl propionate; dibasic esters such as dimethyl succinate, dimethyl glutamate, dimethyl adipate; (di)alkyl carbonate solvents such as ethylene carbonate, propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC); ethers such as tetrahydrofuran, dioxane, and dimethoxyethane; Glycol ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butylyl ether, propylene glycol butyl ether, propylene glycol phenyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether and dipropylene glycol di-n-butyl ether; amide solvents dimethylacetamide and N-methylpyrrolidone; ketone solvents such as acetone, diisobutyl ketone, isobutyl heptyl ketone, isophorone, methyl ethyl ketone, methyl n-amyl ketone and methyl isobutyl ketone; toluene; xylene; diphenylmethane; diisopropylnaphthalene; Petroleum fractions such as Solvesso® products (available from Exxon); and chlorinated hydrocarbon solvents such as 4-chlorotrifluoromethylbenzene and 3,4-bis(dichloro) trifluoromethylbenzene.Any co-solvents or non-reactive diluents of the two-part (2K) composition need not be added independently to one or more ingredients or to the composition itself. Alternatively, one or more components of the composition may be contained in a co-solvent or diluent. Any solvent or diluent contained in crosslinker portion b) of the composition may, in certain embodiments, be free of active hydrogen atoms.It is typical that co-solvents and non-reactive diluents total less than 5 wt%, especially less than 1 wt%, based on the total weight of the composition. By at least partially excluding these co-solvents and non-reactive diluents, the water-based two-part (2K) composition may have a volatile organic compound (VOC) content of at most about 420 g / L, e.g., at most about 360 g / L, such as at most about 300 g / L, or even at most about 240 g / L. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.Methods and ApplicationsIn the two-part (2K) curable compositions, the reactive parts are brought together and mixed so that their curing is initiated. The reactive compounds can be mixed under sufficient shear forces to obtain a homogeneous mixture. This can be achieved without special conditions or special devices. That is, suitable mixing devices may include static mixing devices, magnetic stirring bar apparatus, wire stirring devices, screws, batch mixers, planetary mixers, C.W. Brabender or Banburry® mixers, and high shear mixers such as paddle mixers and rotary stirring machines. In certain embodiments, after mixing the reactive moieties, one or more of the following may be added: water, co-solvent, non-reactive diluent to reduce the viscosity of the composition.For small applications using volumes of less than 2 litres, the typical packages for the two-part (2K) compositions are juxtaposed double cartridges or coaxial cartridges in which two tubular chambers are juxtaposed or nested and closed with pistons: the drive of these pistons allows the extrusion of the parts from the cartridge, advantageously through a closely fitted static or dynamic mixer. For applications with a larger volume, the two parts of the composition can advantageously be stored in barrels or buckets: in this case, the two parts are extruded via hydraulic presses, in particular via follow-up plates, and fed via pipelines to a mixing device which can ensure fine and very homogeneous mixing of the curing agent part and the binder part. The binder part is typically sealed air and moisture tight so that both parts are storable for a long time, ideally 12 months or longer.Non-limiting examples of two-part dispensers and methods that may be suitable for the present disclosure include those described in U.S. Pat. Nos. 6,129,244 and 8,313,006, each of which is expressly incorporated by reference in various non-limiting embodiments.Typically, the compositions described above are applied to the required surface(s) and then cured in situ. Prior to applying the compositions, it is often advisable to pretreat the surfaces in question in order to remove foreign bodies therefrom. This step may optionally facilitate the subsequent adhesion of the compositions to the surfaces. Such treatments are known in the art and may be carried out in one or more steps.In some embodiments, adhesion of the coating compositions to the optionally pretreated substrate surface may be facilitated by the application of a primer layer. Primer compositions may be necessary to assure effective fixation and / or cure times of the adhesive compositions on inactive substrates.The provision of further intermediate layers between the primer and the coating compositions of the present disclosure is not excluded, as will be described below with respect to multilayer coatings.Typically, the compositions are applied to the required surfaces of the substrate by conventional application methods such as: brushing, roll coating, knife coating, printing methods and spraying methods including, but not limited to, air atomized spraying, air assisted spraying, airless spraying and HVLP low pressure spraying.The compositions can be applied to a surface having a wet film thickness of from about 10 to about 500 μm. Applying thinner layers in this area is more economical and reduces the likelihood of producing harmful thick cured areas. When applying thinner coatings or layers, however, care must be taken that no discontinuous cured films are formed. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The curing of the applied compositions typically takes place at temperatures of from about 20 to about 200° C., typically from about 20 to about 160° C. The temperature suitable depends on the specific compounds present and the desired curing rate and can be determined in the individual case by the skilled worker, if appropriate by simple preliminary experiments. For example, in vehicle production applications, a cure temperature of from about 80 to about 160° C., or from about 100 to about 140° C., may be effective. Conversely, in refinish applications, a cure temperature of from about 20 to about 80°C, or from about 40 to about 60°C, may be effective. For large vehicle and transport vehicle applications, such as trucks, buses, and railroad cars, a cure temperature of about 20 to about 80°C may be used. Of course, curing at lower temperatures within the aforementioned ranges is advantageous because it eliminates the need to substantially heat or cool the mixture from the normally prevailing ambient temperature. Optionally, however, the temperature of the mixture formed from the respective components of the composition may be raised above the mixing temperature and / or the application temperature by conventional means including firing and microwave induction. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The present disclosure also provides an article comprising: a metal substrate; and a multilayer coating disposed on the metal substrate, wherein at least one layer of the multilayer coating comprises the cured compositions described herein. While the use of the cured compositions as a primer, such as a primer or sealant, within a multilayer coating is not excluded, the cured coating compositions are more suitable for use in or than: a single color base layer; a single color top coat; and / or a clear coat layer. For example, the cured coating composition can be used in or as transparent clear lacquer(s).An exemplary subject matter is illustrated in the accompanying FIG. 1. The illustrated article (1) comprises: a metal substrate (10); and a multi-layer coating (11) disposed on the metal substrate, the multi-layer coating (11) comprising: a primer layer (110) disposed on the metal substrate; a basecoat layer (120) comprising a color and / or visual effect imparting compound, the basecoat layer disposed on the primer layer (110); and a clearcoat layer (130) comprising the cured product of the two-part (2K) composition described above and disposed on the basecoat layer (120).The primer layer (110) is typically applied to promote adhesion between the substrate surface and the subsequent coating layers. Moreover, the primer layers can serve to improve the physical properties of the entire coating system, in particular corrosion resistance and impact strength. Moreover, the primer layer can contribute to the overall appearance of the coating system by forming a smooth layer onto which the subsequent layers can be applied.The primer layer (110) is shown in FIG. 1 as being disposed on and in direct contact with the metal substrate (10). However, it should be understood that one or more intermediate layers may be disposed between the metal substrate and the primer layer (110). A conversion layer is a representative example of such an intermediate layer. As used herein, the term "conversion" refers to treating the surface of a substrate, thereby chemically converting the surface material to another material. Typically, a metallic or alloyed surface substrate is chemically treated to produce a firmly adherent conversion layer consisting wholly or partly of a stabilized form, for example an oxidized form, of the substrate metal. Such chemical conversion coatings may have high corrosion resistance and provide strong bonding affinity for the subsequent primer layer (110).In FIG. 1, a single primer layer (110) is shown for illustrative purposes only. However, in certain embodiments, there may be more than one primer layer (110). Regardless of whether the primer is applied in one or more layers, the total thickness of the at least one primer layer may typically be between about 10 and about 200 micrometers, for example between about 10 and about 150 micrometers, between about 10 and about 75 micrometers, or between about 20 and about 75 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The basecoat film (120) shown in FIG. 1 comprises a color and / or visual effect imparting compound and is disposed on the basecoat film (110). When the primer has been applied in a multi-layered manner, the base coat layer is disposed on the top primer layer with respect to the surface of the metal substrate (10).In FIG. 1, a single basecoat (120) is shown for illustrative purposes only. However, in certain embodiments, there may be more than one basecoat (120). The lowermost of these basecoat layers may be disposed on and in direct contact with a basecoat (110). Regardless of whether the primer is applied in one or more layers, the total thickness of the at least one basecoat may typically be about 5 to about 100 micrometers, for example about 5 to about 50 micrometers, about 5 to about 40 micrometers, or about 5 to about 30 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In Figure 1, a clear coat (130) containing the cured product of the two part (2K) composition described above is disposed on the base coat (120). When the base coat has been applied in a multi-layer manner, the clear coat layer (130) is disposed on the top base coat layer with respect to the surface of the metal substrate (10). The clear coat (130) typically has good chemical resistance as well as good resistance to mechanical wear and weathering. In addition, the clear coat layer (130) has satisfactory optical properties including transparency and gloss.Here too, FIG. 1 shows only a single clearcoat layer ( 130) for illustrative purposes. However, in certain embodiments, more than one clear coat (130) may be present. The lowermost of these clear lacquer layers may be disposed on and in direct contact with the base lacquer layer (120). Regardless of whether the clearcoat is applied in one or more layers, the total thickness of the at least one clearcoat may typically be from about 10 to about 500 micrometers, for example from about 10 to about 200 micrometers, from about 20 to about 100 micrometers, or from about 30 to about 90 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The or each clear coat (130) of the article may, in certain embodiments, be substantially transparent to visible light. For example, the or each visible light clearcoat may be at least about 85%, at least about 90%, or at least about 95% transparent, as determined from transmission measurements (T R) according to ASTM D1746 (2023).Another exemplary subject matter is illustrated in the accompanying FIG. 2. The illustrated article (1) comprises: a metal substrate (20); and a multi-layer coating (21) disposed on the metal substrate, the multi-layer coating (21) comprising a primer layer (210) disposed on the metal substrate; a basecoat layer (220) comprising a color and / or visual effect imparting compound, the basecoat layer disposed on the primer layer (210); an adhesive layer (225) disposed on the basecoat layer (220); and a clearcoat layer (230) comprising the cured product of the two-part (2K) composition described above and disposed on the basecoat layer (225).The adhesion layer (225) can be interposed between and improve adhesion of a basecoat (220) and a clearcoat (230). Due to this intermediate layer, the adhesive layer (225) may typically be substantially transparent to visible light. For example, the adhesive layer (225) may be at least about 85%, at least about 90%, or at least about 95% transparent to visible light as determined from transmission measurements (T R) according to ASTM D1746 (2023). In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.In FIG. 2, a single adhesion layer ( 225) is shown only for the purpose of illustration. However, in certain embodiments, more than one adhesion layer (225) may be present. The lowermost of these adhesion layers may be disposed on and in direct contact with the basecoat (220); a clearcoat (230) containing the cured product of the two-part (2K) composition described above would be disposed on and in direct contact with the uppermost of the adhesion layers (225) in these embodiments. The total thickness of the at least one adhesion layer may be less than the total thickness of the clear lacquer layer(s) ( 230) in embodiments. Alternatively or additionally, the total thickness of the at least one adhesion layer may be about 1 to about 50 micrometers, such as about 1 to about 25 micrometers, about 5 to about 25 micrometers, or about 5 to about 20 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly contemplated for use herein.The method of making a multilayer coating usually comprises the steps of: i) providing a metal substrate; ii) applying a first layer of a first curable coating composition on and in direct contact with the metal substrate; iii) at least partially curing this first layer; iv) applying a second layer of a second curable coating composition on and in direct contact with the at least partially cured first layer; v) at least partially curing this second layer; vi) applying a third layer of a third curable coating composition on and in direct contact with the at least partially cured second layer; and vii) at least partially curing this third layer. In an iterative method, steps vi) and vii) may be performed and repeated to apply a fourth and further layers to the metal substrate. With respect to the multilayer coatings illustrated in Figures 1 and 2, the first, second, third and further curable compositions provide: at least one undercoat layer, at least one basecoat layer, optionally at least one subbing layer, and at least one clearcoat layer as described above.The metal substrate provided in step i) may typically be pretreated prior to step ii). Such pretreatment may comprise at least one of the following methods: cleaning the surface(s) of the metal substrate; abrading the surface(s) of the metal substrate; applying a corrosion protection layer to the metal substrate; or applying a conversion layer to the metal substrate, as mentioned above.The cleaning serves to remove foreign bodies from the surface(s) of the metal substrate. Cleaning treatments are known in the art and can be carried out in one or more stages, for example, by the use of one or more of the following methods: etching treatment with an acid suitable for the substrate and optionally an oxidizing agent; sonication; plasma treatment including chemical plasma treatment, corona treatment, atmospheric plasma treatment and flame plasma treatment; immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent such as carbon tetrachloride or trichloroethylene; and water rinsing, typically with deionized or demineralized water. In cases where an aqueous alkaline degreasing bath is used, the degreasing agent remaining on the surface can typically be removed by rinsing the substrate surface with deionized or demineralized water.Regardless of the cleaning of the substrate, the surface of the metal substrate (10) may be abraded. Abrading typically involves abrading, which can be carried out, for example, with a vibratory sander having abrasive paper of a certain grain size. After grinding the surface, the metal substrate may be optionally cleaned to remove the dust or other contaminants produced during grinding.As used in the described method, the term "at least partially cured" means that curing of the curable coating composition has been initiated and that, for example, crosslinking of the components of the composition has begun. The term includes any degree of cure upon application of the curing conditions, from the formation of a single crosslink to a fully crosslinked state. The rate and mechanism by which the coating composition cures is dependent on various factors including the ingredients, the functional groups of the ingredients, and the parameters of the curing conditions.The at least partial solidification of a particular coating layer is generally an indication of curing or drying. Drying and curing can, however, also be indicated in another manner, for example by a change in the viscosity of the coating layer, an elevated temperature of the coating layer and / or a change in the transparency / opacity of the coating layer.It may be typical that steps iv) and vi) of the above described application method are not started until the at least partially cured or partially dried preceding layer can substantially retain its shape when exposed to the ambient conditions. By "substantially dimensionally stable" is meant that at least about 50 vol.%, and typically at least about 80 or about 90 vol.%, of the at least partially cured or dried layer retains its shape and does not flow or deform when exposed to the ambient conditions for 5 minutes. Under these circumstances, gravity cannot substantially affect the shape of the at least partially cured or partially dried layer when exposed to ambient conditions.The shape of the at least partially dried or at least partially cured layer may typically affect whether the layer substantially retains its shape. For example, if the layer is rectangular or has another simple shape, the at least partially cured or dried layer may be more deformation resistant than layers with more complex shapes even at lower degrees of cure or even lower degrees of drying.In certain embodiments, the application of each subsequent layer (step iv); step vi)) is done before an at least partially cured layer has reached a final cured state, i.e., while the layer is still "green.". In such embodiments, the application of the layers may be considered "wet-in-wet" such that the adjacent layers bond together at least physically, possibly also chemically. For example, it is possible for the components of the first and subsequent layers to chemically crosslink / cure across the application line, which can have an advantageous effect on the longevity, durability, and appearance of the finished article. The difference between partial curing and final curing state is whether the partially cured layer can be further cured or crosslinked. While this does not exclude that functional groups are present in the final cure state, these groups may remain unreacted due to steric hindrance or other factors.In the aforementioned iterative method, the thickness, width, shape and continuity of each layer may be chosen independently of one another, so that the preceding and the following layers may be the same or different in one or more of these points. For example, a particular subsequent layer may only contact a portion of an exposed surface of the at least partially cured or dried previous layer: depending on the desired shape of the coating layer, the subsequent layer may selectively build up on that layer.The following examples are provided to illustrate the present disclosure and are not intended to limit the scope of the disclosure in any way.ExamplesThe following commercial products are used in the following examples: <row><cell>CE10P:< / cell><cell>Cardura E10P; Versatic acid glycidyl ester available from Hexion.< / cell>< / row><row><cell>BYK® 345:< / cell><cell>Silicone surfactant available from Altana.< / cell>< / row><row><cell>BYK® 333:< / cell><cell>Silicone-containing surface additive available from Altana.< / cell>< / row><row><cell>Tinuvin® 292:< / cell><cell>Hindered amine light stabilizer available from BASF.< / cell>< / row><row><cell>Tinuvin® 1130:< / cell><cell>UV absorbers from the class of hydroxyphenylbenzotriazoles, available from BASF.< / cell>< / row><row><cell>SalientS:< / cell><cell>Dimer fatty acid available from Henkel Corporation.< / cell>< / row><row><cell>Bayhydur XP2655: (HDI) available from Germany< / cell><cell>Hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate covestro.< / cell>< / row><row><cell>Desmodur®N3900:< / cell><cell>Hexamethylene diisocyanate trimer available from Covestro.< / cell>< / row>Unless otherwise indicated, all remaining compounds may be purchased from Sigma Aldrich.<head xml:id="_9bcbca0558">Synthesis Example 1: Preparation of an acrylic copolymer dispersion (AD1)< / head><p xml:id="_9bcbca0559" n="0222">In a reactor equipped with a propeller stirrer, thermometer, condenser and monomer / initiator feed system, 200 g of CE10P and 90 g of ethoxypropanol were charged and heated to about 150° C. A mixture of 52 g of hydroxyethyl methacrylate, 160 g of styrene, 68 g of acrylic acid, 10 g of dicumyl peroxide, 40 g of CE10P and 40 g of ethoxypropanol was added to the reactor over 2.5 hours while the contents were maintained at 150°C. After addition, the contents of the reactor were maintained for 30 minutes. After addition, the contents of the reactor were maintained for 30 minutes.<p xml:id="_9bcbca0560" n="0223">After this holding time, 108 g of hydroxyethyl methacrylate, 30.4 g of acrylic acid, 141.6 g of isobutyl methacrylate, 5 g of dicumyl peroxide and 45 g of ethoxypropanol were added over a period of 2.5 hours while the contents were maintained at 150° C. Following this addition, the feed system was flushed with 5 g ethoxypropanol. After rinsing, the contents of the reactor were maintained at 150°C for 2 hours.<p xml:id="_9bcbca0561" n="0224">The contents of the reactor were cooled to 100°C, and 177 g of ethoxypropanol was distilled off. To the contents was added 33 g of dimethylaminoethanol (DMEA) to obtain a theoretical acid value of 20.5 mg KOH / g, the amount being corrected for the measured acid value. The polymer mixture was diluted with 865 g of water which was preheated to about 70°C.<p xml:id="_9bcbca0562" n="0225">The measured properties of the obtained dispersion were as follows: solid content, 45.1 wt %; viscosity, 3500 centipoise; acid value, 33.6 mg KOH / g; and pH 8.2. In a visual stability determination, the obtained aqueous dispersion showed no sedimentation for 4 weeks when stored at 60° C.<p xml:id="_9bcbca0563" n="0226">The molecular weights of the synthesized copolymer, determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536, were: number average molecular weight (Mn) of 4500 daltons and weight average molecular weight (Mw) of 27500 daltons, number average molecular weight (Mn) of 4200 daltons and weight average molecular weight (Mw) of 17556 daltons.<head xml:id="_9bcbca0564">Synthesis Example 2: Preparation of a solution of a polyester polyol (PE1)< / head><p xml:id="_9bcbca0565" n="0227">A mixture of 911 g trimethylolpropane, 748 g hexahydrophthalic anhydride and 138 g dimer fatty acid (EmpolS) 1008 from Henkel was heated to 250° C. The esterification was carried out with removal of water until an acid number of less than 5 mg KOH / g was reached. After the reaction mixture was cooled to below 125 °C, the solid content was adjusted to 70 wt% with 90 g xylene and 641 g methoxypropyl acetate.<p xml:id="_9bcbca0566" n="0228">The polyester polyol obtained had a calculated hydroxyl number of 345 mg KOH / g and an acid number of 4.5 mg KOH / g. The calculated hydroxyl functionality was 5.6 and the calculated number average molecular weight (Mn) determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536 was 920 daltons.<head xml:id="_9bcbca0567">Example 1< / head><p xml:id="_9bcbca0568" n="0229">The dispersions (AD1, PE1) described above were used to prepare two-part (2K) clearcoat compositions. The binder part a) of the two-part compositions was obtained by mixing the components listed in Table 1 below. Similarly, crosslinker portion b) of the two-part composition was obtained by mixing Desmodur® N390, Bayhydur XP2655 and solvents in the amounts indicated. The table describes the preparation of: a reference coating composition 1 (RCC1) and two coating compositions (CC1-CC2) according to the present disclosure. Table 1<title desc="title">Table 1Part a)Acrylic copolymer dispersion (AD1)92,2782,4082,15Polyester Example B5,475,452-Ethylhexane-1,3-diol2,02Propylene glycol methyl ether1,311,011,31Butylglycol acetate0,510,510,50Mineral Spirits White Spirits1,621,621,61N,N-dimethylethanolamine0,000,140,14Deionized water2,026,584,54Byk 3450,580,580,58Byk 333 3330,190,190,19Tinuvin 2920,660,660,661130 Tinuvin0,850,850,85Total weight of part a)100,00100,00100,00Part b)Desmodur®N390047,347,347,3Bayhydur XP265523,823,823,8Butylglycol acetate23,723,723,7Mineral Spirits White Spirits5,25,25,2Total weight of part b)100,0100,0100,0The above-mentioned parts a) and b) were mixed at a weight ratio (a:b) of 100:35 to form coating compositions (RCC1, CC1-CC2) each having a molar ratio of active hydrogen atoms to -NCO groups (here, OH / NCO) of 0.7:1 to 1.4:1. The viscosity of each composition was adjusted with deionized water to a viscosity of about 20-28 cps, which was determined at room temperature using a Brookfield CAP2000 viscometer (400 U / min, spindle no. 4). The clearcoat materials obtained in this way were each sprayed onto black-coated steel plates and baked at 60° C. for 30 minutes. Then, the obtained coatings were subjected to the following evaluation tests, the results of which are shown in Table 2 below.Wave Scan: The wave scanning to simulate visual perception was performed with a Wavescan DOI available from BYK-Gardner GmbH. The instrument provided a laser spot light source that illuminated the sample at a 60° angle: an associated detector measured the reflected light intensity at the same but opposite angle. The long-wave signal (structure size>0.6 mm) and the short-wave signal (structure size<0.6 mm) were each filtered out of the measurement signal using a mathematical filter function. The measurement device was rolled over the surface and measured the optical profile of the surface over a defined distance point by point. The long term ripple value reported in Table 2 represents the variance of the long wave signal amplitude and was normalized to a unitless value in the range of 0 to 100, where 0 represents the least variance (best) and 100 represents the most variance (worst). Similarly, the short term ripple value represents the variance of the short wave signal amplitude and has been normalized to a unitless value in the range of 0 to 100, where 0 represents the least variance (best) and 100 represents the most variance (worst).Image Sharpness (DOI): This is a measure of how clear and sharp a reflected image appears in the applied coating and was determined here using ASTM D5767-18 Standard Test Method for Instrumental Measurement of Discontinuity-of-Image (DOI) Gloss of Coated Surfaces. The scale values obtained by the measurement methods of this test method range from 0 to 100, with a value of 100 representing a perfect DOI (image clarity). The further the value of 100 decreases, the more the image is distorted.Jacksonville Etch Value: The etch value of the varnishes was determined by exposing five (5) replicates of the varnish coated steel panels (30 cm x 30 cm) at an exposure location on Blood Island, Jacksonville, Florida (USA). Exposure took place from end May to end August. The defects were evaluated on a rating scale ranging from 1 (no visible etch) to 10 (high etch), as described in GM Material Specification 9984157 (2009). The grades of the five replicates of each clear coat were averaged to obtain the etch data listed in Table 2 below. Table 2 Table 2Image Sharpness (DOI)95,596,596,5Long-term ripple value44,81,7Short Term Ripple Value2,42,21,6Jacksonville etch value:7,56,46,6As compared with Reference Coating Composition 1, addition of the polyester resin to CC1 gave an improved appearance as shown by the lower short wave value and the higher DOI value in Table 2. In addition, CC1 exhibited improved Jacksonville etch resistance.The presence of the low molecular weight diol in combination with the polyester resin in the coating composition CC2 promotes improvement in both long and short term curl values without substantially compromising image sharpness results or etch resistance.It should be understood that various changes and modifications to the exemplary embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present subject matter and without sacrificing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. It is to be understood that the features of the dependent claims may be embodied in the compositions and methods of any of the independent claims.Many modifications and other embodiments of the disclosure set forth herein will occur to those skilled in the art to which this disclosure pertains once having learned the teachings of the foregoing description. It is therefore to be understood that the disclosure is not limited to the specific embodiments and that modifications and other embodiments are intended to be included within the scope of the appended claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 6,129,244

[0190] U.S. Pat. No. 8,313,006

[0190] Cited Non-Patent LiteratureKohlerin J. Am. Chem. Soc., 49, 3181 (1927

[0023]

Claims

A two part (2K) water-based coating composition comprising: water; a) a binder part comprising: (a1) at least one hydroxyl functional (meth)acrylate copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups; and b) a cross-linker part comprising: at least one polyisocyanate compound having pendant -NCO groups, wherein the (a2) non-aromatic polyester has a number average molecular weight (Mn) of about 500 to about 5000 daltons, an acid number of about 0 to about 30 mg KOH / g, a calculated hydroxyl number of about 100 to about 600 mg KOH / g, and a calculated hydroxyl functionality of about 2 to about 8; and wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is about 5:1 to about 1:5.The coating composition of claim 1, wherein the weight ratio of solids of (a1) to solids of (a2) is from about 100:1 to about 100:35.Coating composition according to Claim 1 or Claim 2 having a content of volatile organic compounds (VOC) measured according to ISO 11890-2: 2006 of at most about 420 g / l.The coating composition according to any one of claims 1 to 3, wherein the hydroxyl functional (meth)acrylate copolymer is prepared from a monomer mixture by a two-step polymerization process.The coating composition of any one of claims 1 to 4, wherein the (meth)acrylate copolymer is the reaction product of monomers in a monomer mixture comprising, based on the total weight of the monomers: from about 10 to about 80 wt% i) of at least one hydroxyl functional adduct of a mono-epoxy ester and an unsaturated carboxylic acid; from about 0 to about 40 wt% ii) of at least one hydroxyl functional unsaturated monomer different from component i); from about 1 to about 8 wt% iii) of at least one unsaturated acid functional monomer; and from about 0 to about 70 wt% iv) of at least one polymerizable unsaturated monomer different from monomer components i), ii) and iii); wherein the (meth)acrylate copolymer is prepared by a skew feed polymerization process having at least two feed streams; wherein one feed stream comprises: I) from about 60 to about 100% by weight of the total amount of i) in the monomer mixture; II) from about 0 to about 60% by weight of the total amount of ii) in the monomer mixture; III) from about 0 to about 30% by weight of the total amount of iii) in the monomer mixture; and IV) from about 0 to about 80% by weight of the total amount of iv) in the monomer mixture; and wherein the remaining one or more feed streams comprise the remainder of i) to iv).The coating composition of claim 5, wherein the monomer mixture comprises: from about 20 to about 60 wt% i); from about 10 to about 30 wt% ii); from about 2 to about 6 wt% iii); and from about 20 to about 60 wt% iv).The coating composition of claim 6, wherein the monomer mixture comprises, based on the total weight of the monomers of the monomer mixture: from about 20 to about 60 wt% iv-1) of at least one (meth)acrylate monomer of formula MA: H 2 C=CG a CO 2 R a( MA) wherein: G a is hydrogen, halogen, or methyl; and R a is: C 1- C 18- alkyl; C 2- C 18- heteroalkyl; C3-C18cycloalkyl; C 2- C 8- heterocycloalkyl; C 2- C 8- alkenyl or C 2- C 8- alkynyl; from about 0 to about 15 wt% iv-2) of at least one vinyl aromatic monomer; and optionally from about 0 to about 25 wt% iv-3) of at least one further polymerizable unsaturated monomer different from monomers iv)-1 and iv)-2.The coating composition according to claim 7, wherein in the formula (MA): R a represents C 1- C 18- alkyl or C 3- C 18- cycloalkyl.The coating composition of claim 7 or 8, wherein the (meth)acrylate monomer of formula (MA), when homopolymerized, yields a homopolymer having a glass transition temperature (Tg) greater than about 30°C.The coating composition of any one of claims 7 to 9, wherein iv-1) comprises at least one (meth)acrylate monomer selected from: cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; Dihydrodicyclopentandienyl(meth)acrylat; 4-tert-butylcyclohexyl (meth)acrylate; and mixtures thereof.The coating composition of any one of claims 7 to 10, wherein the vinyl aromatic monomer of iv-2) has the following formula (VA): wherein: R 1 is H or C 1- C 4- alkyl; each R 2 is independently hydrogen or C 1- C 4- alkyl; Ar is unsubstituted phenyl or phenyl substituted with 1 to 5 substituents, each substituent being independently halogen or C 1- C 4- alkyl; and n is an integer from 0 to 4.The coating composition of claim 11, wherein in formula (VA): R 1 is H or methyl; each R 2 is independently H or methyl; Ar is unsubstituted phenyl or phenyl substituted with 1 to 5 substituents, each substituent being independently halogen or C 1- C 4- alkyl; and n is 0 or 1.The coating composition of claim 11 or 12, wherein iv-2) comprises at least one vinyl aromatic monomer selected from: styrene; α-methylstyrene; 2-methylstyrene; 3-methylstyrene; 4-methylstyrene; 2-tert-butylstyrene; 4-tert-butylstyrene; 2-chlorostyrene; 4-chlorostyrene; and mixtures thereof.The coating composition according to any one of claims 5 to 13, wherein the monomer mixture comprises at least one monomer having the general formula AM1: R 4- C(H)=C(R 5)- A-(R 6 O) [a]- R 7( AM1) wherein: R 4 is H, methyl, CO 2 H or CH 2 CO 2 H; R 5 is hydrogen, halogen or methyl; A is -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH 2 C(O)N-, -C(O)N-, -CH 2-, - O-C(O)-, -NHC(O)O-, -NHC(O)NH-, -C 6 H 4( R 8)- NH-C(O)-O-, -C 6 H 4( R 8)- NH-C(O)-NH-, -C(O)O-CH 2- CH(CH 2 OH)-O-, -C(O)O-CH 2- CH(CH 2 OH)-NH-, -C(O)O-CH 2- CH 2- CH(OH)-O-, -C(O)O-CH 2- CH 2- CH(OH)-NH-, -CH 2- O-CH 2- CH(CH 2 OH)-O-, -CH 2- O-CH2-CH2CH(OH)-O-, -CH 2- O-CH 2- CH(CH 2 OH)-NH-, or -CH 2- O-CH 2- CH 2- CH(OH)-NH-; each R 6 independently represents C 2- C 4- alkylene; [a] has a value of about 5 to about 100; R 7 represents C1-C30 alkyl, C1-C30 hydroxyalkyl, C1-C30 aminoalkyl, C 3- C 18- cycloalkyl, C 2- C 5- heterocycloalkyl, C 2- C 20- alkenyl, C 2- C 12- alkynyl, C 6- C 18- aryl, C7-C24 alkaryl or C7-C24 aralkyl; and R 8 is -CH 2- or -(C)(CH 3)2-.The coating composition of claim 14, wherein in formula (AM1): R 4 is H, methyl, CO 2 H, or CH 2 CO 2 H; R 5 is hydrogen, halogen, or methyl; A is -CH 2 C(O)O-, or -C(O)O-; each R 6 is independently C 2- C4 alkylene; [a] has a value from about 10 to about 30; and R 7 is C 6- C 30- alkyl, C 6- C 30- hydroxyalkyl, C 6- C 30- aminoalkyl, C 3- C 18- cycloalkyl, C 6- C18aryl, C7-C18alkaryl or C7-C18aralkyl.The coating composition of claim 14 or 15, wherein in formula (AM1): R 4 is H, methyl, CO 2 H, or CH 2 CO 2 H; R 5 is hydrogen, halogen, or methyl; A is -C(O)O-; each R 6 is independently C 2- C 3- alkylene; [a] has a value from about 10 to about 30; and R 7 is C 6- C 30- alkyl, C 6- C 30- hydroxyalkyl or C 6- C 30- aminoalkyl.The coating composition of any one of claims 14 to 16, wherein the monomer of formula AM1 is selected from: Laurylethoxylat[a](meth)acrylat ; Cetylethoxylat[a](meth)acrylat ; Stearylethoxylat[a](meth)acrylat ; Behenylethoxylat[a](meth)acrylat ; Laurylethoxylat[a]itaconat ; Cetylethoxylat[a]itaconat ; Stearylethoxylat[a]itaconat ; Behenylethoxylat[a]itaconat ; lauryl ethoxylate [a] maleate ; cetyl ethoxylate [a] maleate ; stearyl ethoxylate [a] maleate ; Behenylethoxylat[a]maleat ; and mixtures thereof, wherein [a] represents the number of moles of ethoxylation and has a value from about 10 to about 30.The coating composition of any one of claims 1 to 17, wherein the non-aromatic polyester of (a2) has: a number average molecular weight (Mn) of about 500 to about 1500 daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of about 4 to about 8.The coating composition of any one of claims 1 to 18, wherein the non-aromatic polyester of (a2) is obtained by the polycondensation reaction of: at least one hydroxyl functional component (a2h); at least one carboxyl functional component (a2c); and optionally at least one hydroxy carboxylic acid component (a2hc), wherein the polycondensation reaction comprises a stoichiometric excess of hydroxyl groups to carboxyl groups.The coating composition of claim 19, wherein: the hydroxyl functional component (a2h) comprises, based on the total weight of the hydroxyl functional component: about 75 to about 100 wt% of at least one polyol having 3 to 6 hydroxyl groups; and about 0 to about 25 wt% of at least one diol; and the carboxyl functional component (a2c) comprises, based on the weight of the carboxyl functional component: about 75 to about 100 wt% of at least one dicarboxylic acid; and about 0 to about 25 wt% of at least one monocarboxylic acid.The coating composition of claim 20, wherein the at least one dicarboxylic acid comprises a dimer fatty acid in an amount of from about 5 to about 50 wt% based on the weight of the carboxyl functional component.The coating composition of any one of claims 1 to 21, wherein binder part a) further comprises: (a3) at least one non-polymeric acyclic polyol having a weight average molecular weight (Mw) of less than about 300 daltons and a water solubility at about 20°C of less than about 6 g / 100 mL of water, wherein (a3) is present in an amount of up to about 10 wt% based on the weight of binder part a).The coating composition of any one of claims 1 to 22, wherein binder part a) further comprises: (a4) at least one non-polymeric, cycloaliphatic polyol having a weight average molecular weight (Mw) of less than about 300 daltons, wherein (a4) is present in an amount of up to about 10 wt% based on the weight of binder part a).The coating composition according to any one of claims 1 to 23, wherein the polyisocyanate compound comprises 2 to 5 -NCO functional groups.The coating composition of any one of claims 1 to 24, wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is about 3:1 to about 1:3.A cured product obtained from the water-based coating composition according to any one of claims 1 to 25.An article comprising: a metal substrate; and a multilayer coating disposed on the metal substrate, wherein at least one layer of the multilayer coating comprises the cured product of claim 26.The article of claim 27, wherein the multi-layer coating comprises: a primer layer disposed on and in direct contact with the substrate; at least one basecoat layer comprising a color and / or visual effect imparting compound, wherein at least one basecoat layer is disposed on and in direct contact with the primer layer; and a clearcoat layer comprising the cured product of claim 26 and disposed on and in direct contact with at least one basecoat layer.

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