Two-component (2k) aqueous coating composition

Abstract

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

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a two-component (2K) waterborne coating composition comprising a binder part and a crosslinker part. The binder part comprises a water-dilutable hydroxy-functional (meth)acrylate copolymer and a non-aromatic polyester having active hydrogen groups. The crosslinker part of the composition comprises at least one polyisocyanate compound having -NCO side groups. The coating composition can be used as a clear coating composition for the finishing or refinishing of vehicles. BACKGROUND ART

[0002] Automotive refinishing refers to compositions and methods for repairing damaged automotive topcoats, usually but not necessarily the topcoats provided by the original equipment manufacturer (OEM). For example, a damaged automotive component may include some defective areas where at least a portion of a previously applied coating layer has been removed, and in some cases, such removal may expose the bare substrate of the component. Thus, the refinishing operation may include repairing or replacing the entire damaged automotive body component, repairing one or more coating layers on the component, or a combination of both operations. The size of the defective area and the presence or absence of a coating layer around the defective area (which, if present, may act as an anchor for the refinishing coating composition) generally determine the type of operation to be performed.

[0003] Regarding the repair of coating layers, the refinishing process generally includes the following sequential steps: sanding the surface to be refinished; applying at least one primer composition; optionally sanding the applied primer composition; applying at least one basecoat composition to achieve the desired optical appearance, such as the desired color, gloss, or distinctness of image (DOI); and applying a clearcoat composition that can be sufficiently clear or translucent to allow the underlying coating layers to be seen through it.

[0004] Heretofore, coating compositions used in refinishing operations, including clearcoat compositions, have been solvent-based and thus contain large amounts of volatile organic compounds (VOCs). However, the use of such compounds is regulated. For example, in the United States, the emission standards for volatile organic compounds are governed by Section 183(e) of the Clean Air Act (Act), and for the mandatory emission levels of automotive refinish coatings, reference may be made to Section 7511b(e) of Title 42 of the United States Code (42 United States Code (U.S.C.) § 7511b(e)) and Subpart B of Part 59 of Title 40 of the Code of Federal Regulations (40 Code of Federal Regulations (CFR) Part 59 Subpart B).

[0005] Recently, the coating industry has made great progress in complying with state and federal regulations regarding VOC emissions by developing high-solids solventborne coating compositions and waterborne coating compositions.

[0006] Waterborne coating compositions – compared to existing solventborne alternatives – can not only have the wetting and leveling properties required for repair applications, but can also be used immediately by users without significant retooling of existing application equipment. However, waterborne compositions must be dehydrated for proper crosslinking and curing to occur. Given the boiling point of water, it is difficult to remove water by flash drying because removing water typically requires fairly stringent baking conditions in which the air flow and the humidity in the oven or drying chamber must be carefully controlled.

[0007] Since the drying of waterborne compositions imposes an energy burden and delays the repair process, volatile organic cosolvents or diluents are added to such compositions to mitigate their drying characteristics. However, if the above regulations become more stringent regarding the VOC levels permitted in automotive repair coating compositions, the presence of such cosolvents and diluents may become undesirable.

[0008] Accordingly, there is a desire to develop waterborne coating compositions having performance equivalent to solventborne coatings. More specifically, such waterborne compositions should exhibit good leveling on the application surface and be dehydratable under medium or low baking conditions during application. In addition, such compositions should exhibit appropriate optical properties to facilitate their use in repair applications, such as being used as a clear coating composition.

[0009] Other beneficial features and characteristics of the various compositions will become apparent in the following detailed description and examples. SUMMARY OF THE INVENTION

[0010] The present disclosure provides a two-component (2K) waterborne coating composition comprising:

[0011] Water;

[0012] a) a binder portion comprising:

[0013] (a1) at least one water-dilutable hydroxy-functional (meth)acrylate copolymer; and

[0014] (a2) at least one non-aromatic polyester having an active hydrogen group; and

[0015] b) a crosslinker portion comprising at least one polyisocyanate compound having an -NCO side group,

[0016] The number average molecular weight (Mn) of the non-aromatic polyester of component (a2) is from about 500 to about 5000 daltons, the acid value is from about 0 to about 30 mg KOH / g, the calculated hydroxyl value is from about 100 to about 600 mg KOH / g, and the calculated hydroxyl functionality is from about 2 to about 8; and

[0017] wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is from about 5:1 to about 1:5.

[0018] The present disclosure further provides a cured product obtained from the two-component (2K) waterborne coating composition.

[0019] The present disclosure also further provides an article comprising: a metal substrate; and a multi-layer coating disposed on the metal substrate, wherein at least one layer of the multi-layer coating comprises the cured product. In one embodiment of the article, the multi-layer coating comprises: a primer layer disposed on and in direct contact with the substrate; at least one basecoat layer comprising a compound imparting color and / or visual effect, wherein the basecoat layer is disposed on and in direct contact with the primer layer; and a clearcoat layer comprising the cured product, wherein the clearcoat layer is disposed on and in direct contact with the basecoat layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] From the following discussion in conjunction with the accompanying drawings, various other objects, advantages and features of the present disclosure will become apparent to those skilled in the art, wherein:

[0021] Figure 1 is a side cross-sectional view of an article according to a first embodiment of the present disclosure; and

[0022] Figure 2 is a side cross-sectional view of an article according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or its implementation or use. Furthermore, there is no intention to be bound by any theory presented in the foregoing background or the following detailed description.

[0024] Generally speaking, the embodiments of the present disclosure relate to water-dilutable hydroxy-functional (meth)acrylate copolymers, non-aromatic polyesters having active hydrogen groups, compositions including them, and methods for forming them. For the sake of brevity, conventional techniques related to the preparation of such polymers and such compositions may not be described in detail herein. In addition, the various tasks and process steps described herein can be incorporated into a more comprehensive program or process having additional steps or functions not described in detail herein. In particular, the individual steps in the manufacture of such polymers and related compositions are well known, and thus, for the sake of brevity, many conventional steps will only be briefly described or will be omitted entirely without providing well-known process details.

[0025] The polymers and compositions disclosed herein may suitably comprise, consist of, or consist essentially of the components, elements, and process delineations described herein. The illustrative embodiments disclosed herein can be suitably implemented in the absence of any elements not specifically disclosed herein.

[0026] Definition

[0027] The term "consisting essentially of" can describe various non-limiting embodiments that do not contain one or more of the optional compounds described herein, or one or more additives, solvents, polymers, resins, etc. that are not described herein but are used in the art.

[0028] In various embodiments, the term "about" can describe a value ±0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10%. In addition, it is contemplated that in various non-limiting embodiments, all numerical values provided herein, except for actual examples, are approximate values, where the endpoints or specific values should be construed as "about" or "approximate" the stated value.

[0029] The molecular weights mentioned in this specification are generally measured using gel permeation chromatography (GPC) with polystyrene calibration standards, as performed according to ASTM 3536.

[0030] The "acid value" used herein refers to the mass of potassium hydroxide (KOH) in milligrams required to neutralize one gram of the composition. The acid value can be determined by potentiometry.

[0031] The term "hydroxyl value" used herein refers to the mass of potassium hydroxide in milligrams required to neutralize the acetic acid absorbed when acetylating one gram of a chemical substance containing free hydroxyl groups. The hydroxyl value can be determined according to DIN 53240.

[0032] The term "active hydrogen atom" refers to a hydrogen atom that is active as shown by the Zerewitinoff test described by Kohler in J. Am. Chem. Soc., 49, 3181 (1927), which is hereby expressly incorporated by reference in its various non-limiting embodiments. Active hydrogen atoms can be derived from hydroxyl groups, thiols, primary amines, secondary amines, and carboxyl groups.

[0033] As used herein, the term softening point (°C.) for waxes refers to the Ring & Ball softening point, which, unless otherwise specified, is measured according to ASTM E28.

[0034] Unless otherwise specified, the viscosity of the compositions described herein is measured using a Brookfield viscometer model CAP2000 under standard conditions of 20 °C and 50% relative humidity (RH). The viscometer is calibrated using hydrocarbon oils of known viscosity in the range of 1 - 10,000 centipoise. Calibration is performed using a set of RV rotors connected to the viscometer. The coating composition is measured using rotor number 4 at a speed of 400 revolutions per minute for 1 minute until the viscometer reaches equilibrium. The viscosity corresponding to the equilibrium reading is then calculated using the calibration results.

[0035] Unless otherwise indicated, the term "particle size" refers to the longest axis of the particle. For generally spherical particles, the longest axis is the diameter.

[0036] The term "average volume particle size" (Dv50) as used herein refers to the particle size at which 50% of the sampled particle volume is greater than and 50% of the sampled particle volume is less than the Dv50 value. Similarly, if the term "Dv90" is used, it refers to the particle size at which 90% of the sampled particle volume is less than and 10% of the sampled particle volume is greater than the Dv90 value. Particle size is determined in this document using an Anton Paar particle size analyzer (PSA) 1190 by laser diffraction.

[0037] Room temperature as used herein refers to 23 °C ± 2 °C.

[0038] The term "ambient conditions" as used herein refers to the temperature and pressure of the environment in which the composition is located or the environment in which the coating or the coating substrate is located.

[0039] In the context of the present disclosure, a "two-component (2K) composition" refers to a composition in which the first part a) and the second part b) are stored separately in different containers due to their (high) reactivity. The two parts are only mixed before or during application and then react, usually without the need for additional activation to form bonds, thereby forming a polymer network. To accelerate the crosslinking reaction, a higher temperature can be applied.

[0040] The term "water-dilutable (co)polymer" as used herein means that the (co)polymer exists in the form of particles in water, these particles are dispersed or suspended, and generally have stable anti-aggregation properties after further dilution with water. In contrast to water-soluble (co)polymers, the diluted solution of a water-dilutable polymer (about 1 g / liter) exhibits scattering phenomena when analyzed using any other technique well-known in the field of dynamic light scattering or particle analysis.

[0041] The term "transparent coating" as used herein means a coating layer in a multi-layer coating, which has sufficient transparency or translucency to enable the underlying coating layer to be seen through it. The term "transparent" does not require absolute transparency or translucency.

[0042] The term "metal" as used herein refers to any type of metal, metal alloy or mixture thereof. The term "alloy" as used herein means a substance formed by the close combination of two or more metals or a metal and a non-metal, usually by melting together and dissolving in each other during melting.

[0043] The term "catalytic amount" as used herein means a sub-stoichiometric catalytic amount relative to the reactants, unless otherwise specified.

[0044] The term "radical initiator" as used herein means a compound that decomposes into multiple moieties that are uncharged but each have at least one unpaired electron when exposed to sufficient energy (such as in the form of light or heat). In particular, radical thermal initiators generate radicals upon activation by thermal energy, such as upon heating or irradiation in the infrared or microwave wavelength regions.

[0045] In various non-limiting embodiments, all isomers and chiral options of each compound described herein are explicitly used herein.

[0046] It is understood that the subscripts of polymers are usually described as averages because the synthesis of polymers typically results in a distribution of various individual molecules.

[0047] The term "monomer" as used herein means a substance that can undergo polymerization to provide a structural unit for the chemical structure of a polymer. The term "monofunctional" as used herein means having one polymerizable moiety. The term "polyfunctional" as used herein means having multiple polymerizable moieties.

[0048] The term "blocked" as used herein means a compound having a "blocking group" such that its reactive functional groups are not available until the blocking group is removed or degraded. The blocking group can be selectively removed or degraded at an appropriate position in the synthesis sequence: the triggering event can be, in particular, moisture, heat or irradiation, etc. Examples of blocked isocyanates include those that co-react with phenol, methyl ethyl ketone oxime or ∈-caprolactam.

[0049] As used herein, the term "fatty acid" refers to a monocarboxylic acid consisting of a fatty chain including 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 include one or more hydroxyl groups. Exemplary fatty acids include: linoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxystearic acid, linolenic acid, and eicosanoic acid.

[0050] The term "dimer fatty acid" may be used interchangeably with "dimerized fatty acid" and generally refers to a compound including two fatty acid subunits, wherein the respective fatty acid side chains are covalently bonded by a bond or a linking group. Thus, as described herein, the dimer fatty acid may be a covalent fatty dimer. The dimer fatty acid may be a heterodimer or a homodimer and may be cyclic or acyclic. The term is intended to cover derivatives of dimer fatty acids that have a functional carboxyl group and have substantially the same properties as dicarboxylic acids when reacting with diols and dihydric alcohols to form polyesters: esters and reactive derivatives forming esters, such as acyl halides and acid anhydrides, may be mentioned.

[0051] As used herein, "(meth)acrylyl" is an abbreviation for "acryl" and / or "methacrylyl". Thus, the term "(meth)acrylamide" refers to the collective term for acrylamide and methacrylamide.

[0052] As used herein, "C1-C n alkyl" refers to a monovalent group or moiety having 1 to n carbon atoms, which is a residue of an alkane and includes straight-chain and branched organic groups. Thus, "C1-C 18 alkyl" refers to a monovalent group or moiety having 1 - 18 carbon atoms, which is a residue of an alkane and includes straight-chain 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 may be substituted by one or more halogens. Where applicable to a given moiety (R), the tolerance of one or more non-halogen substituents in the alkyl group will be described in the specification.

[0053] As used herein, the term "C1-C 18 hydroxyalkyl" refers to an HO-(alkyl) group having 1 to 18 carbon atoms, wherein the point of attachment of the substituent is through an oxygen atom and the alkyl group is as defined above.

[0054] "Alkoxy" refers to a monovalent group represented by -OA, wherein A is an alkyl group: non-limiting examples are methoxy, ethoxy, and isopropoxy. As used herein, "C1-C 18The term "alkoxyalkyl" 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 (—CH2OCH3), 2-methoxyethyl (—CH2CH2OCH3), and 2-ethoxyethyl. Similarly, as used herein, "C7-C 18 The term "alkoxyaryl" refers to an aryl having an alkoxy substituent as defined above, wherein the moiety (aryl-O-alkyl) contains a total of 7 to 18 carbon atoms.

[0055] The term "C2-C4 alkylene" as used herein refers to a saturated divalent hydrocarbon residue having 2-4 carbon atoms.

[0056] “C3-C 18 The term "cycloalkyl" includes saturated, monocyclic or polycyclic hydrocarbon groups or moieties having 3 to 18 carbon atoms. In the present disclosure, such cycloalkyl groups or moieties may be unsubstituted or may be substituted with one or more halogens. Where applicable to a given moiety (R), the allowable non-halogen substituents in the cycloalkyl will be described in the specification. Examples of cycloalkyl include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, and norbornyl.

[0057] As used herein, "C2-C 18 "Alkenyl" refers to a hydrocarbon group or moiety having 2-18 carbon atoms and at least one ethylenic unsaturation unit. The alkenyl group or moiety may be straight-chain, branched or cyclic and may optionally be substituted with one or more halogens. Where applicable to a given moiety (R), the allowable non-halogen substituents in the alkenyl group will be described in the specification. The term "alkenyl" also includes residues having "cis" and "trans" configurations, or having "E" and "Z" configurations, as known to those skilled in the art. C2-C 20 Examples of alkenyl include: —CH═CH2, —CH═CHCH3, —CH2CH═CH2, —C(═CH2)(CH3), —CH═CHCH2CH3, —CH2CH═CHCH3, —CH2CH2CH═CH2, —CH═C(CH3)2, —CH2C(═CH2)(CH3), —C(═CH2)CH2CH3, —C(CH3)═CHCH3, —C(CH3)CH═CH2, —CH═CHCH2CH2CH3, —CH2CH═CHCH2CH 3、—CH2CH2CH═CHCH3, —CH2CH2CH2CH═CH2, —C(═CH2)CH2CH2CH3, —C(CH3)═CHCH2CH3, —CH(CH3)CH═CHCH, —CH(CH3)CH2CH═CH2, —CH2CH═C(CH3)2, 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.

[0058] As used herein, "C6-C 18 "aryl", used alone or as part of a larger moiety (such as "aralkyl"), refers to monocyclic, bicyclic, and tricyclic ring systems, where the monocyclic ring system is aromatic, or at least one of the bicyclic or tricyclic ring systems is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2-3 membered carbocycles. In the present disclosure, such aryl may be unsubstituted or may be substituted with one or more halogens. Where applicable to a given moiety (R), the allowable non-halogen substituents on the aryl group will be described in the specification. Exemplary aryl groups include: phenyl, (C1-C4)alkylphenyl such as tolyl and ethylphenyl, indenyl, naphthyl, tetrahydronaphthyl, tetrahydroindenyl, tetrahydroanthracenyl; and anthracenyl.

[0059] As used herein, "alkylaryl" refers to an alkyl-substituted aryl group or moiety, and "substituted alkylaryl" refers to an alkylaryl group or moiety that also bears one or more of the above substituents. In addition, "aralkyl" as used herein refers to an alkyl group or moiety substituted with an aryl as defined above.

[0060] The term "hetero" as used herein refers to a group or moiety containing one or more heteroatoms (such as N, O, Si, and S). Thus, for example, "heterocyclic" refers to a cyclic group containing N, O, Si, or S in the ring structure. "Heteroalkyl", "heterocycloalkyl", and "heteroaryl" moieties refer to alkyl, cycloalkyl, and aryl as defined above, respectively, which contain N, O, Si, or S in their structures.

[0061] The term "non-polymer" as used herein is a descriptor for a compound that is not constructed from repeating structural units. Non-polymeric compounds can be regarded as unique individual structural units.

[0062] The term "non-aromatic" as used herein as a descriptor for a monomer refers to a compound that does not have an aromatic nucleus. The term is intended to include aliphatic and cycloaliphatic compounds, which may be saturated or unsaturated, the latter case containing non-aromatic carbon-carbon double bonds or carbon-carbon triple bonds. Non-aromatic polymeric compounds may be substantially free of an aromatic nucleus in their main chain, such that the polymer may contain an aromatic nucleus only due to process impurities of aliphatic or cycloaliphatic monomer structural units.

[0063] As used herein, the term "base" refers to a class of substances that are capable of abstracting a proton in a polar or nonpolar solvent; or are capable of providing a hydroxide anion (OH - ).

[0064] In various embodiments, the term "free of" describes embodiments that contain less than about 5, 4, 3, 2, 1, 0.5 or 0.1 wt.% of a relevant component, compound, moiety, functional group, element or ion, using a suitable weight basis understandable to those skilled in the art. In other embodiments, the term "free of" describes embodiments that contain about 0 wt.% of a relevant component, compound, moiety, functional group, element or ion.

[0065] As used herein, the term "anhydrous" is equivalent to the term "free of water".

[0066] Looking back, the aqueous compositions include water and: a) a binder portion; and b) a crosslinker portion. Based on the weight of the composition, the amount of water present can be 30 - 80 wt.%. For example, the amount of water present can be 35 - 70 wt.%, 40 - 60 wt.%, 45 - 55 wt.%, 45 - 52 wt.% or 46 to 51 wt.%. At such water contents, drying and aggregation of the composition—when applied to a substrate—can be achieved without high energy consumption and time costs. The viscosity of the composition measured at room temperature can be, for example, 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. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values and numerical ranges above, are expressly contemplated for use herein.

[0067] Water in the two-component (2K) composition does not have to be added separately to any one or more of the components or to the composition itself. Alternatively, one or more of the components in the composition can also be provided in water.

[0068] In certain embodiments, the binder portion a) of the two-component (2K) composition contains water such that the binder portion a) provides at least a portion of the water of the two-component (2K) composition. However, addition of supplementary water to the composition during or after mixing the water-containing binder portion a) with the crosslinker portion b) is not excluded. Such addition of supplementary water can be used to reduce the viscosity of the composition, which can be useful for certain methods of applying the composition (such as spraying) to a substrate as described below.

[0069] Part A)

[0070] Now, looking at the binder part a) of the two-component (2K) water-based composition, this part comprises: (a1) at least one water-dilutable hydroxy-functional (meth)acrylate copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups.

[0071] At least one hydroxy-functional (meth)acrylate copolymer of component (a1) is water-dilutable but is generally compatible with polyisocyanates, which include especially hydrophobic polyisocyanates not hydrophilically modified with polyether or polyester groups, etc. Thus, the two-component coating composition itself has water-dilutability, which can provide important flexibility for an operator to apply the coating composition, for example, in vehicle repair operations.

[0072] The presence of the non-aromatic polyester in the binder part of the composition improves the appearance of the cured coating thus obtained. This non-aromatic polyester can also make the cured coating exhibit weather resistance.

[0073] Copolymer composition (A1)

[0074] The at least one water-dilutable hydroxy-functional (meth)acrylate copolymer is commercially available. Exemplary commercially available copolymers include: products obtainable from Covestro under the trademark ; and products obtainable from Allnex under the trademark .

[0075] However, in one embodiment, the water-dilutable hydroxy-functional (meth)acrylate copolymer of component (a1) is obtained by polymerization of a monomer mixture which, based on the total weight of the monomers in the monomer mixture, comprises:

[0076] 10 - 80 wt.%, for example 20 - 60 wt.%, of i) at least one hydroxy-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid;

[0077] 0 - 40 wt.%, for example 10 - 30 wt.%, of ii) at least one hydroxy-functional unsaturated monomer different from component i);

[0078] 1 - 8 wt.%, for example 2 - 6 wt.%, of iii) at least one unsaturated acid-functional monomer; and

[0079] 0 - 70 wt.%, for example 20 - 60 wt.%, of iv) at least one polymerizable unsaturated monomer different from monomer components i), ii) and iii);

[0080] The monomer components of the exemplary copolymer of the component (a1) will be described in more detail below. It should be noted that the polymerization of the component monomers is generally free radical solution polymerization. Two-step, free radical solution polymerization can be used, and one exemplary embodiment is skew feed polymerization.

[0081] Monomer component i) : Hydroxy-functional adduct

[0082] In this exemplary embodiment, based on the total weight of the monomers in the monomer mixture, the monomer mixture contains 10-80 wt.% of i) at least one hydroxy-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid. For example, based on the total weight of the monomers in the monomer mixture, the (meth)acrylic acid copolymer (a1) may contain 20-60 wt.% or 30-60 wt.% of i) the at least one hydroxy-functional adduct. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0083] Generally, the adduct is formed by a nucleophilic addition reaction of a monoepoxy ester with an acid to form a hydroxyalkyl ester. This acid ring-opening reaction generally requires a catalyst, such as a tertiary amine, a quaternary ammonium compound, and a transition metal compound.

[0084] The reactant monoepoxy ester is generally a glycidyl ester derived from an aliphatic saturated monocarboxylic acid having a tertiary or quaternary carbon atom at the α(α-) position. Representative reactant monoepoxy esters are glycidyl esters of saturated α,α-dialkylalkane monocarboxylic acids having 5-13 carbon atoms or 9-11 carbon atoms in the acid molecule. Exemplary reactant monoepoxy esters include: glycidyl versatate commercially available from Hexion as Cardura E10; glycidyl pivalate commercially available from Hexion as Cardura E5; and reaction products of tertiary fatty acids having up to 12 carbon atoms with epichlorohydrin.

[0085] The reactant acid-functional compound can be an aliphatic unsaturated monocarboxylic acid, and non-limiting examples thereof include: α,β-monoenyl unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; C1-C6 alkyl half-esters of α,β-monoenyl unsaturated dicarboxylic acids such as fumaric acid and maleic acid; and C1-C6 alkyl esters of α,β-monoenyl unsaturated tricarboxylic acids having one free carboxylic acid group. In various embodiments, acrylic acid and / or methacrylic acid are used as the acid-functional compound reactant.

[0086] Monomer component ii) : Hydroxy-functional ethylenically unsaturated monomer

[0087] In this exemplary embodiment, based on the total weight of the monomers in the monomer mixture, the monomer mixture comprises 10-30 wt.% of ii) at least one hydroxy-functional monomer different from monomer component i). For example, based on the total weight of the monomers in the monomer mixture, the monomer mixture can comprise 10-25 wt.% or 10-20 wt.% of ii) at least one hydroxy-functional monomer. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0088] Exemplary monomers of component ii) include hydroxyalkyl esters having primary or secondary hydroxy groups, which hydroxyalkyl esters are derived from α,β-monoethenyl unsaturated monocarboxylic acids. For example, these can include hydroxyalkyl esters derived from acrylic acid, methacrylic acid, crotonic acid or isocrotonic acid.

[0089] In one embodiment, monomer component ii) comprises at least one hydroxy(meth)acrylate monomer represented by the formula HMA:

[0090] H2C=CG a CO2R h (HMA)

[0091] Wherein: G a is hydrogen, halogen or methyl; and

[0092] R h is C1-C 18 hydroxyalkyl.

[0093] Typical monomers conforming to the formula HMA include those wherein: G a is hydrogen, halogen or methyl; and R h is C1-C 12 hydroxyalkyl. Monomers wherein G a is hydrogen or methyl and R h is C1-C6 hydroxyalkyl can also be used.

[0094] Examples of (meth)acrylate monomers conforming to the formula HMA include: 2-hydroxyethyl (meth)acrylate, 1-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-hydroxybutyl (meth)acrylate.

[0095] Monomer component iii) : ethylenically unsaturated acid functional monomers

[0096] In an exemplary embodiment, based on the total weight of the monomers in the monomer mixture, the monomer mixture comprises 2-6 wt.% of iii) at least one ethylenically unsaturated acid-functional monomer. For example, component iii) may account for 2-5 wt.% or 2-4 wt.% of the monomer mixture. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0097] Without intending to limit the present disclosure, the unsaturated acid-functional monomers may be selected from: ethylenically unsaturated carboxylic acids; ethylenically unsaturated sulfonic acids; vinylphosphonic acid; and mixtures thereof. Suitable ethylenically unsaturated sulfonic acids include, for example, vinylsulfonic acid, styrenesulfonic acid, and acrylamidomethylpropanesulfonic acid.

[0098] Generally, 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; C1-C6 alkyl half-esters of α,β-monoethylenically unsaturated dicarboxylic acids; α,β-monoethylenically unsaturated tricarboxylic acids; C1-C6 alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids having 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.

[0099] For completeness, although the above unsaturated acid-functional monomers may be used in the free acid form, it is not excluded to partially or completely neutralize the constituent acid groups of the monomers with a suitable base, provided that this does not affect their participation in the copolymerization reaction.

[0100] Monomer component iv) : Other polymerizable unsaturated monomers

[0101] In this exemplary embodiment, the monomer mixture further comprises at least one ethylenically unsaturated monomer different from the monomers of i), ii), and iii). For example, based on the total weight of the monomers in the monomer mixture, monomer component iv) may comprise:

[0102] 20-60 wt.%, such as 25-50 wt.%, of iv-1) at least one (meth)acrylate monomer represented by the formula MA:

[0103] H2C=CG a CO2R a (MA)

[0104] Wherein: G a is hydrogen, halogen, or methyl; and

[0105] R a is: C1-C18 Alkyl; C2-C 18 Heteroalkyl; C3-C 18 Cycloalkyl;

[0106] C2-C8 hetero cycloalkyl; C2-C8 alkenyl; or C2-C8 alkynyl;

[0107] 0-15 wt.%, such as 4-14 wt.% or 10-14 wt.% of iv-2) at least one vinyl aromatic monomer; and

[0108] 0-25 wt.% of iv-3) at least one other polymerizable unsaturated monomer different from monomers iv-1) and iv-2).

[0109] In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0110] In typical monomers conforming to formula MA: G a Is hydrogen, halogen or methyl; and R a Is C1-C 18 Alkyl or C3-C 18 Cycloalkyl. Monomers in which G a Is hydrogen or methyl can also be used.

[0111] Examples of (meth)acrylate monomers conforming to formula MA that can be used alone or in combination include: methyl (meth)acrylate, ethyl (meth)acrylate, 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, dihydrodicyclopentadienyl (meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate, ethylene glycol monoethyl ether (meth)acrylate, ethylene glycol monolauryl ether (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, trifluoroethyl (meth)acrylate; and perfluorooctyl (meth)acrylate.

[0112] In some embodiments, the (meth)acrylate monomers constituting component iv) of the monomer mixture may include "hard" monomers. The term "hard monomer" generally describes monomers that produce a homopolymer with a glass transition temperature (Tg) greater than about 30 °C upon homopolymerization. For example, monomer component iv) may include at least one (meth)acrylate monomer regarded as a hard monomer.

[0113] Exemplary hard monomers include: cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; dicyclopentadienyl (meth)acrylate; and 4-tert-butylcyclohexyl (meth)acrylate.

[0114] As described above, the monomers of component iv-2) can be completely excluded from the monomer mixture. However, in other embodiments, the monomer mixture may contain vinyl aromatic monomers of iv-2). In a representative embodiment, the monomer component iv-2) includes at least one vinyl aromatic monomer of formula (VA):

[0115]

[0116] wherein: R 1 is H or a C1-C4 alkyl group;

[0117] each R 2 is independently hydrogen or a C1-C4 alkyl group;

[0118] Ar is an unsubstituted phenyl group or a phenyl group substituted with 1-5 substituents, wherein each substituent is independently a halogen or a C1-C4 alkyl group; and

[0119] n is an integer from 0 to 4.

[0120] Typical monomers conforming to formula VA are those wherein: R 1 is H or methyl; each R 2 is independently H or methyl; Ar is an unsubstituted phenyl group or a phenyl group substituted with 1-5 substituents, wherein each substituent is independently a halogen or a C1-C4 alkyl group; and n is 0 or 1.

[0121] Exemplary vinyl aromatic monomers conforming to formula (VA) (which can be used alone or in combination) include: styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-tert-butylstyrene, 4-tert-butylstyrene, 2-chlorostyrene, and 4-chlorostyrene.

[0122] Also as mentioned above, based on the total weight of the monomers in the monomer mixture, the monomer mixture of this embodiment of component (a1) may contain 0-25 wt.% of iv-3) at least one polymerizable unsaturated monomer different from components i), ii), iii), iv-1) and iv-2). For example, based on the total weight of the monomers in the monomer mixture, the monomer mixture may contain 1-20 wt.%, 1-15 wt.% or 1-10 wt.% of the monomers of component iv-3). Alternatively, the monomers of component iv-3) may be completely excluded. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0123] Exemplary monomers present in monomer component iv-3) that may be used alone or in combination include: aromatic (meth)acrylate monomers; (meth)acrylate-functionalized oligomers; nitrogen (N-)-functionalized ethylenically unsaturated monomers; silane-functionalized ethylenically unsaturated monomers such as methacryloxypropyltri(C1-C5)alkoxysilane and vinyltri(C1-C5)alkoxysilane; acetoacetoxy-functionalized unsaturated monomers such as acetoacetoxyethyl methacrylate; vinyl esters; vinyl halides and vinylidene dihalides; vinyl ethers; alkyl vinyl ketones; cycloalkyl vinyl ketones; heterocyclic aliphatic vinyl compounds; poly(meth)acrylates of alkane polyols; poly(meth)acrylates of alkylene oxide polyols; and poly(C2-C3)alkylene glycol di(meth)acrylates.

[0124] Suitable aromatic (meth)acrylate monomers include those represented by formula AII:

[0125] H2C=CG b CO2R b (AII)

[0126] Wherein: G b is hydrogen, halogen or methyl; and

[0127] R b is C6-C 18 aryl, C1-C9 heteroaryl, C7-C 18 alkoxyaryl, C7-C 18 alkaryl or C7-C 18 aralkyl.

[0128] Exemplary (meth)acrylate monomers conforming to formula (AII) (which may be used alone or in combination) include: benzyl (meth)acrylate, phenoxyethyl (meth)acrylate and phenoxypropyl (meth)acrylate.

[0129] Suitable (meth)acrylate-functionalized oligomers may 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. One or more acrylate and / or methacrylate groups may be attached to the backbone of the oligomer, and these (meth)acrylate functional groups may be located at the terminal positions of the oligomer and / or may be distributed along the oligomer backbone. Typically, the (meth)acrylate-functionalized oligomer reacts as a monomer to form a copolymer (a1): each molecule has two or more (meth)acrylate functional groups; and / or, has a weight average molecular weight (Mw) of from about 300 to about 1000 daltons. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0130] Regarding the nitrogen (N-) functionalized ethylenically unsaturated monomers, the nitrogen functional group may be a nitrile or a urea, and may also include imide, amide or amino nitrogen atoms.

[0131] 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: acryloylmorpholine, 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-hydroxymethylacrylamide, 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.

[0132] The copolymer (a1) does not exclude containing residues of at least one amino (meth)acrylate monomer. The term "amino (meth)acrylate" as used herein refers to a derivative of methacrylic acid or acrylic acid having a primary, secondary, or tertiary amino group: the amino group can be part of a straight-chain, branched, or cyclic aliphatic group or an aromatic group. The at least one amino (meth)acrylate monomer can be a tertiary amino (meth)acrylate, for example, particularly N,N-dialkylaminoalkyl (meth)acrylates. In various embodiments, one or more of N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl methacrylate, or N,N-dimethylaminopropyl acrylate can be used.

[0133] In another non-limiting embodiment, the monomer mixture comprises at least one vinyl monomer having a heterocyclic nitrogen structure. Exemplary heterocyclic structures have 5 or 6 members and may include oxygen atoms in addition to nitrogen: for example, the 5- or 6-membered ring may represent a pyridine, pyrimidine, pyridazine, imidazoline, imidazole, oxazoline, oxazole or morpholine ring. Examples that may be used alone or in combination include: N-vinylcaprolactam (NVC), vinyl methyl oxazolidinone (VMOX), N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, and N-vinylpyrrolidone.

[0134] Exemplary vinyl esters that may be copolymerized in the present disclosure include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and VEOVA provided by Shell Chemical Company TM series monomers. Exemplary copolymerizable poly(meth)acrylates of alkane polyols include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Exemplary copolymerizable poly(meth)acrylates of alkylene oxide polyols include diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate, and di(pentanediol) dimethacrylate.

[0135] In one embodiment, the monomer mixture comprises at least one monomer having the general formula AM1:

[0136] R 4 -C(H)═C(R 5 )—A—(R 6 O) [a] —R 7 (AM1)

[0137] Where: R 4 is H, methyl, CO2H or CH2CO2H;

[0138] R 5 is hydrogen, halogen or methyl;

[0139] A is -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH2C(O)N-,

[0140] -C(O)N-, -CH2-, -O-C(O)-, -NHC(O)O-, -NHC(O)NH-,

[0141] -C6H4(R 8 )-NH-C(O)-O-, -C6H4(R 8 )-NH-C(O)-NH-,

[0142] -C(O)O-CH2-CH(CH2OH)-O-, -C(O)O-CH2-CH(CH2OH)-NH-,

[0143] -C(O)O-CH2-CH2-CH(OH)-O-, -C(O)O-CH2-CH2-CH(OH)-NH-,

[0144] -CH2-O-CH2-CH(CH2OH)-O-, -CH2-O-CH2-CH2-CH(OH)-O-,

[0145] -CH2-O-CH2-CH(CH2OH)-NH-, or -CH2-O-CH2-CH2-CH(OH)-NH-;

[0146] Each R 6 is independently a C2-C4 alkylene;

[0147] [a] has a value of 5 to 100;

[0148] R 7 is C1-C 30 alkyl, C1-C 30 hydroxyalkyl, C1-C 30 aminoalkyl, C3-C 18 cycloalkyl, C2-C5 heterocycloalkyl, C2-C 20 alkenyl, C2-C 12 alkynyl, C6-C 18 aryl, C7-C 24 alkaryl or C7-C 24 aralkyl; and

[0149] R 8 is -CH2- or -(C)(CH3)2-.

[0150] Typical monomers conforming to formula AM1 are those where: R 4 is H, methyl, CO2H or CH2CO2H; R 5 is hydrogen, halogen or methyl; A is -CH2C(O)O- or -C(O)O-; each R 6 is independently a C2-C4 alkylene; [a] has a value of 10 to 30; R 7 is C6-C 30 alkyl, C6-C 30 hydroxyalkyl, C6-C30 aminoalkyl, C3-C 18 cycloalkyl, C6-C 18 aryl, C7-C 18 alkaryl or C7-C 18 aralkyl.

[0151] Representative monomers conforming to formula AM1 are those wherein: R 4 is H, methyl, CO2H or CH2CO2H; R 5 is hydrogen, halogen or methyl; A is -C(O)O-; each R 6 is independently a C2-C3 alkylene; the value of [a] is from 10 to 30; and, R 7 is C6-C 30 alkyl, C6-C 30 hydroxyalkyl or C6-C 30 aminoalkyl.

[0152] Exemplary monomers conforming to formula AM1 that can be copolymerized alone or in combination include: lauryl ethoxylate[a](meth)acrylate; cetyl ethoxylate[a](meth)acrylate; stearyl ethoxylate[a](meth)acrylate; behenyl ethoxylate[a](meth)acrylate; lauryl ethoxylate[a]itaconate; cetyl ethoxylate[a]itaconate; stearyl ethoxylate[a]itaconate; behenyl ethoxylate[a]itaconate; lauryl ethoxylate[a]maleate; cetyl ethoxylate[a]maleate; stearyl ethoxylate[a]maleate; and behenyl ethoxylate[a]maleate, where [a] represents the molar number of the ethoxylate and the value is from 10 to 30. In other words, each of the above compounds can be described as an ethoxylated compound with an ethoxylation degree of 10 to 30 moles of ethylene oxide. In certain embodiments, the value of the parameter [a] can be from 15 to 30 or from 15 to 25. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0153] Hydroxy-functional (meth)acrylic acid copolymers are generally produced by free radical solution copolymerization, in which monomers form a solution in a solvent that can also dissolve the copolymer, and the monomers are polymerized by free radical polymerization reactions, i.e., in the presence of a free radical initiator. Generally, the aforementioned monomers are typically charged into a reflux reactor in the presence of at least one organic solvent and a free radical initiator. The concentration of monomers in the solution can vary, but generally the weight ratio of monomers to solvent is from 1:20 to 2:1, such as 1:2 to 1.5:1. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0154] Conventional polymerization conditions commonly used include a temperature range of 25 - 250 °C, such as 50 - 250 °C or 75 - 250 °C. The polymerization pressure is generally not critical, and thus, the polymerization can be carried out under sub-atmospheric, atmospheric, or super-atmospheric pressure. If necessary, the polymerization reaction can be carried out under anaerobic conditions: the reaction vessel can be equipped with an inert, dry gaseous blanket, such as a nitrogen, helium, or argon blanket. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0155] Generally, based on the total weight of the polymerizable monomers, the amount of the at least one free radical initiator is 0.1 - 1 wt.%, such as 0.1 - 0.5 wt.%. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0156] An exemplary class of suitable free radical initiators is organic peroxides, such as selected from: cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxy esters, and peroxyketals.

[0157] The free radical initiator can be known in the art. For example, the free radical initiator can include hydrogen peroxide. Alternatively, the free radical initiator can include organic hydroperoxides. For completeness, the definition of hydroperoxides includes substances such as organic peroxides or organic peroxy acid esters that decompose or hydrolyze to form organic hydroperoxides in situ: examples of such peroxides and peroxy acid esters are cyclohexyl peroxide and hydroxycyclohexyl peroxide, and tert-butyl peroxybenzoate, respectively.

[0158] In one embodiment of the present disclosure, the free radical initiator includes at least one hydroperoxide represented by the following formula:

[0159] R p OOH

[0160] Wherein: R p is an aliphatic or aromatic group containing up to 18 carbon atoms, and usually, wherein: R p is C1-C 12 alkyl, C6-C1 aryl or C7-C 18 arylalkyl.

[0161] The one or more radical initiators may include: cumene hydroperoxide (CHP), p-menthane hydroperoxide, tert-butyl hydroperoxide (TBH), tert-butyl perbenzoate, tert-butyl perpivalate, di-tert-butyl peroxide, tert-butyl peracetate, tert-butyl per-2-ethylhexanoate, tert-amyl hydroperoxide, 1,2,3,4-tetramethylbutyl hydroperoxide, benzoyl peroxide, dibenzoyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, diacetyl peroxide, butyl 4,4-bis(tert-butylperoxy)valerate, p-chlorobenzoyl peroxide, tert-butyl cumyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxy-3-hexyne, and 4-methyl-2,2-di-tert-butylperoxypentane.

[0162] Azopolymerization initiators may also be used, selected from: azonitriles, azoesters, azoamides, azoamidines, azoimidazolines, macromolecular azo initiators, and combinations thereof.

[0163] 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-cyanopentanoic acid), 2,2'-azobis(2-methylpropionic acid dimethyl ester), 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-methylpropamidine) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropamidine] tetrahydrate, 4,4-azobis(4-cyanopentanoic acid), a polymer with α,ω-bis(3-aminopropyl)polydimethylsiloxane (VPS-1001, obtained from Wako Pure Chemical Industries, Ltd.), and a 4,4'-azobis(4-cyanopentanoic acid)-polyethylene glycol polymer (VPE-0201, obtained from Wako Pure Chemical Industries, Ltd.).

[0164] Redox initiators can also be used, including combinations of oxidizing agents and reducing agents. Suitable oxidizing agents can be selected from cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, diperoxydicarbonates, peresters, peroxoketals, and mixtures thereof. Corresponding reducing agents can be selected from: alkali metal sulfites; alkali metal bisulfites; alkali metal metabisulfites; formaldehyde sulfoxylate; alkali metal salts of aliphatic sulfonic acids; alkali metal hydrosulfides; and polyvalent metal salts, especially cobalt(II) salts and iron(II) salts, such as iron(II) sulfate, ammonium iron(II) sulfate, or iron(II) phosphate; dihydroxymaleic acid; benzoin; ascorbic acid; reducing sugars, such as sorbose, glucose, fructose, and / or dihydroxyacetone; and mixtures thereof.

[0165] Free radical polymerization can be carried out in the presence of a chain transfer agent, the role of which is to transfer free radicals, reduce the molecular weight of the resulting polymer and / or control the chain growth during the polymerization process. When a chain transfer agent is added, based on the total weight of the polymerizable monomers, the chain transfer agent can account for 0.01-1 wt.% of the mixture. The amounts of the polymerization initiator and any chain transfer agent present will affect the number average molecular weight of the (co)polymer, but the choice of solvent may also be relevant. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0166] Free radical polymerization reactions are typically carried out in organic solvents (typically polar solvents). An effective polar solvent may have a boiling point of at least 20 °C, such as at least 30 °C or at least 40 °C, measured at 1 atmosphere (1.01325 bar). Examples of such polar solvents that can be used alone or in combination include: C1-C8 alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and isobutanol; acetonitrile; N,N-bis(C1-C4)alkylamides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); hexamethylphosphoramide; N-methylpyrrolidone; pyridine; esters such as (C1-C8)alkyl acetates, ethoxydiethylene glycol acetate, dimethyl glutarate, dimethyl maleate, dipropyl oxalate, ethyl lactate, benzyl benzoate, butyloctyl 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 one exemplary embodiment, the polymerization reaction is carried out in the presence of a (C1-C8)alkyl acetate (such as ethyl acetate).

[0167] The hydroxy-functional (meth)acrylate copolymer (a1) can be prepared from a monomer mixture by a bias-fed polymerization process using at least two monomer feed streams. In one embodiment, the first feed stream comprises: I) 60 - 100% by weight of a hydroxy-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid i), based on the total weight of component i) monomers in the monomer mixture; II) 0 - 60% by weight of a hydroxy-functional unsaturated monomer ii), based on the total weight of component ii) monomers in the monomer mixture; III) 0 - 30% by weight of an unsaturated acid-functional monomer iii), based on the total weight of component iii) monomers in the monomer mixture; and IV) 0 - 80% by weight of other polymerizable unsaturated monomers iv), based on the total weight of component iv) monomers in the monomer mixture. The remaining one or more feed streams contain the balance of monomer components i) to iv). In various non-limiting embodiments, all numerical values and ranges of values, including integers and fractions, including and between the values and ranges of values above, are expressly contemplated for use herein.

[0168] In such bias-fed polymerization, the total amount of free radical initiator to be added can be added all at once at the start of the first feed step. However, typically, multiple portions of the free radical initiator are added over time, more specifically, a portion is added to each feed stream. Each initiator portion dedicated to a particular feed stream can be introduced as a single dose, stepwise, or continuously into the reflux reactor.

[0169] Similarly, the total amount of organic solvent can be injected all at once at the start of the first feed step. However, typically, multiple portions of the organic solvent are added over time, more specifically, a portion is added to each feed stream. Generally, the solvent portion dedicated to a particular feed stream can be added to the reflux reactor before or simultaneously with the start of monomer addition.

[0170] In certain embodiments of the bias-fed polymerization, after the first feed stream is added, the reactor contents can be rinsed with an organic solvent. Similarly, an intermediate rinse step can be carried out between each subsequent feed step.

[0171] The progress of the polymerization reaction can be monitored by potentiometric titration, and the progress of each feed step as appropriate, to determine the hydroxyl value and / or acid value. When these values reach a predetermined value based on the desired conversion level, the reactor contents are typically cooled and then partially or fully neutralized by adding an appropriate amount of base. The reactor contents containing the hydroxy-functional (meth)acrylate copolymer polymer (a1) can then be converted to an aqueous dispersion by forward or reverse dilution with water.

[0172] Component (a2)

[0173] The binder portion a) of the two-component (2K) composition of the present disclosure comprises (a2) at least one non-aromatic polyester having active hydrogen groups, wherein the non-aromatic polyester has: a number average molecular weight (Mn) of from about 500 to about 5000 daltons; an acid value of from about 0 to about 30 mg KOH / g; a calculated hydroxyl value of from about 100 to about 600 mg KOH / g; and a calculated hydroxyl functionality of from about 2 to about 8. In various non-limiting embodiments, all numerical values and ranges, including integers and fractions, including values within and between the above numerical values and ranges, are expressly contemplated for use herein.

[0174] In important embodiments, the non-aromatic polyester (a2) has: a number average molecular weight (Mn) of from about 500 to about 1500 daltons; an acid value of from about 0 to about 30 mg KOH / g; a calculated hydroxyl value of from about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of from about 4 to about 8. In various non-limiting embodiments, all numerical values and ranges, including integers and fractions, including values within and between the above numerical values and ranges, are expressly contemplated for use herein.

[0175] Typically, the weight ratio of the solids of the hydroxy-functional (meth)acrylate copolymer of component (a1) to the solids of the polyester of component (a2) 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 numerical values and ranges, including integers and fractions, including values within and between the above numerical values and ranges, are expressly contemplated for use herein.

[0176] The non-aromatic polyester is typically prepared by polycondensing the following components: at least one hydroxy-functional component (a2h); at least one carboxy-functional component (a2c); and optionally at least one hydroxycarboxylic acid component (a2hc). These components can be selected according to type and quantity such that the non-aromatic polyester obtains the above molecular weight, acid value, hydroxyl value and functionality. Generally, the polycondensation reaction can be described by a stoichiometric excess of hydroxyl groups over carboxyl groups. Usually, the stoichiometric excess of hydroxyl groups over carboxyl groups is 5 - 40 mol%, such as 5 - 35 mol%, 5 - 30 mol% or 5 - 25 mol%. In various non-limiting embodiments, all numerical values and ranges, including integers and fractions, including values within and between the above numerical values, are expressly contemplated for use herein.

[0177] The hydroxy-functional component (a2h) may include, based on the weight of the hydroxy-functional component: 75-100 wt.%, such as 80-100 wt.% or 90-100 wt.%, of at least one polyol having 3-6 hydroxyl groups; 0-25 wt.%, such as 0-20 wt.% or 0-10 wt.%, of at least one diol. In certain embodiments, the hydroxy-functional component (a2h) may include, based on the weight of the hydroxy-functional component: 95-100 wt.% of at least one polyol having 3-6 hydroxyl groups; and 0-5 wt.% of at least one diol. In other embodiments, the hydroxy-functional component (a2h) consists essentially of the at least one polyol having 3 to 6 hydroxyl groups, or consists of the at least one polyol having 3 to 6 hydroxyl groups. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the values above, are expressly contemplated for use herein.

[0178] Suitable polyols having 3 to 6 hydroxyl groups can be saturated or unsaturated, and can be aliphatic or cycloaliphatic compounds: the molecular weight of such compounds is generally 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, pyranopentose, 6-deoxyhexopyranose, 2,5-anhydrohexitol, 1,5-anhydrohexitol, 6-deoxyhexose, 1-deoxyhexitol, and pentitol. An exemplary polyol having six hydroxyl groups is D-glucitol (sorbitol). In embodiments, 2-ethyl-2-hydroxymethyl-1,3-propanediol (trimethylolpropane), 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol), or a mixture thereof can be used.

[0179] The present disclosure does not exclude the use of (C2-C4) alkylene oxide adducts of the above diols, triols, and higher polyols as polyol reactants having 3 to 6 hydroxyl groups.

[0180] The diols suitable for the hydroxyl-functional component can be saturated or unsaturated and can be aliphatic or cycloaliphatic dihydroxy compounds. The molecular weight of the reactant diol can typically be 250 daltons or less. As used herein, the term "diol" can include its equivalent ester-forming derivatives, provided that the molecular weight requirement applies only to the diol and not to its derivatives. Exemplary ester-forming derivatives include the acetate of the diol and, for example, ethylene carbonate or ethylene oxide of ethylene glycol.

[0181] Typical diols are those having 2-10 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; hexanediol; cyclohexanedimethanol; and polyoxyalkylene glycols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and tetrapropylene glycol. Mixtures of these diols can be used.

[0182] Based on the weight of the carboxyl-functional component, the carboxyl-functional component (a2c) can comprise: 75-100 wt.%, such as 80-100 wt.% or 90-100 wt.%, of at least one dicarboxylic acid; and 0-25 wt.%, such as 0-20 wt.% or 0-10 wt.%, of at least one monocarboxylic acid. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0183] The dicarboxylic acids suitable herein include aliphatic and / or cycloaliphatic dicarboxylic acids. The molecular weight of the dicarboxylic acid is typically less than 600 daltons. As used herein, the term "dicarboxylic acid" includes dicarboxylic acid equivalents having two functional carboxyl groups, which act substantially the same as dicarboxylic acids in reacting with polyols to form polyesters. These equivalents include esters and ester-forming reactive derivatives such as acyl halides and acid anhydrides, provided that the above molecular weight ranges relate only to the acid and not to its equivalent esters or ester-forming derivatives. Thus, esters of dicarboxylic acids having a molecular weight greater than 300 daltons or acid equivalents of dicarboxylic acids having a molecular weight greater than 300 daltons are also included, provided that the molecular weight of the acid is below 300 daltons. In addition, the dicarboxylic acid can contain any substituent groups or combinations thereof that do not significantly interfere with the formation of the polymers of the present disclosure and the use of the polymers.

[0184] 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 alkyldicarboxylic acids include: glutaric acid, adipic acid, suberic acid, succinic acid, sebacic acid, azelaic acid, and malonic acid. For example, adipic acid can be used.

[0185] Dimer fatty acids can be used as the dicarboxylic acid reactants in the above polyester synthesis reaction. Exemplary dimer fatty acids include C 36 -C 44 aliphatic dicarboxylic acids, which can be prepared by oxidative coupling of C 18 -C 22 unsaturated monocarboxylic acids. Dimer acids obtained by oxidative coupling of oleic acid, linoleic acid or tall oil fatty acids can be used. However, in those embodiments where at least one dimer fatty acid is used in the reaction, there is usually at least one non-dimer dicarboxylic acid. More specifically, in the case of using at least one dimer fatty acid, the amount of the dimer fatty acid that can react is 5-50 wt.%, usually 5-40 wt.%, 5-30 wt.% or 5-25 wt.%, based on the total weight of the carboxyl functional components. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are explicitly contemplated for use herein.

[0186] Monocarboxylic acids that are suitable reactants in the polycondensation reaction include aliphatic and / or cycloaliphatic monocarboxylic acids. The molecular weight of these monocarboxylic acids can generally be less than 300 daltons. Exemplary monocarboxylic acids that can be used alone or in combination include: formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, 2-ethylhexanoic acid, octanoic acid, isononanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, palmitic acid and stearic acid.

[0187] (Cyclo)aliphatic hydroxycarboxylic acid component (a2hc) can optionally participate in the polycondensation reaction to produce a non-aromatic polyester polyol (a2). When the hydroxycarboxylic acid is present, the total amount of the hydroxycarboxylic acid is generally at most 10 wt.%, based on the total weight of the reactant compounds (a2h, a2c and a2hc). Exemplary hydroxycarboxylic acids include: 12-hydroxy stearic acid, 6-hydroxyhexanoic acid, citric acid, tartaric acid and dimethylolpropionic acid. The corresponding lactones can also be used instead of the monohydroxycarboxylic acids as reactants.

[0188] Typically herein, the reaction mixture provided to the aforementioned polycondensation reaction is substantially free of solvent. In addition, the initial reaction mixture is substantially free of added water. However, if the reaction is carried out in solution, suitable solvents can be non-reactive, substantially anhydrous organic liquids that can dissolve at least 1 wt.% and usually more than 10 wt.% of the polyester product at 25°C. Suitable organic solvents that can be used alone or in combination include: aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as heptane and decane; cycloaliphatic 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.

[0189] The polycondensation reaction can be carried out in the presence of a suitable catalyst. Common catalysts include acid catalysts and organometallic catalysts. Examples of the latter are alkoxides (alkoxylates), carboxylates, and chelates of titanium, zirconium, and tin. Typically, the catalyst is a titanium alkoxide, titanium carboxylate, or titanium chelate catalyst.

[0190] Exemplary titanium alkoxides include tetramethyl titanate (titanium methoxide); tetraethyl titanate; tetrapropyl titanate; tetraisopropyl titanate; tetrabutyl titanate; tetraamyl titanate; tetrahexyl titanate; tetraoctyl titanate; tetranonyl titanate; tetra(dodecyl) titanate; tetra(hexadecyl) titanate; tetra(octadecyl) titanate; tetradecyl titanate; tetraheptyl titanate; and mixtures thereof. The tin or zirconium counterparts of the above alcoholates can be partially substituted as catalysts.

[0191] Typically, the amount of the catalyst is 0.1 - 5 wt.%, for example 0.1 - 2.0 wt.%, 0.1 - 1.5 wt.%, or 0.1 - 1.0 wt.%, based on the total weight of the reactants (a2h, a2c, and a2hc). In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0192] The polycondensation reaction can also be carried out in the presence of at least one stabilizer. Typical stabilizers (the amount of which is conventionally 0.01 - 5 wt.% based on the total weight of the reactants (a2h, a2c, and a2hc)) can be: hydroquinone and its alkylated derivatives; phenolic compounds having electron-withdrawing substituents; and quinone compounds. Specific examples of such stabilizing compounds (which can 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-tert-butylcatechol; 4-methoxyphenol; methylhydroquinone; 4-chloro-2-nitrophenol; 2,4-dinitro-p-cresol; 2,4-dinitrophenol; and phenothiazine. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0193] In the case of using a stabilizer in the polycondensation reaction, one or more known electron donors that form electron-donor-acceptor complexes can be further added to the reactant mixture. These electron donors (usually 0.01 - 1 wt.% based on the total weight of the reactants (a2h, a2c, and a2hc)) include: 1-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2-(2-ethyl-4-methylimidazolyl)-1-cyanoethane, and 2-undecylimidazole. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0194] When synthesizing a polyester, the reactants, catalyst, and any stabilizer and electron donor used are typically charged into a suitable reaction vessel equipped with a distillation device. Before charging into the reaction vessel, the vessel has usually been dried and purged with an inert gas (such as nitrogen or argon), and an inert atmosphere can be maintained inside the reaction vessel during the reaction. The temperature of the vessel is typically set according to the lowest boiling point of the reactants, which is usually an alcohol. In various embodiments, temperatures of about 125 to about 300 °C or about 125 to about 275 °C can be considered standard conditions. During the initial period, the vessel can be maintained at atmospheric pressure, but once it is observed that no more water is being distilled off, at least a partial vacuum can be applied to the vessel to drive the polycondensation reaction to completion. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0195] The reaction can be monitored by analyzing the acid value (Av) of the reactant mixture over time. When the determined acid value is 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 reaction usually stops. The time to reach this point will depend on various factors such as temperature, catalyst type, and the reactants used: but generally ranges from about 0.5 to about 20 hours, such as about 1 to about 8 hours or about 2 to about 6 hours. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0196] The polyester synthesized by the polycondensation reaction can be separated and purified by methods known in the art, including filtration, extraction, evaporation, distillation, or chromatography.

[0197] Non-polymeric polyols (a3), (a4)

[0198] Adding a specific low-molecular-weight non-polymeric polyol to part a) of the composition can improve the moisture resistance of the coating obtained from the composition and facilitate easier mixing between the two parts of the composition. Any improvement in this mixing can translate into better applicability of the coating composition and an improved appearance of the resulting coating.

[0199] In one embodiment, the binder part a) of the two-component (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 having a water solubility of less than about 6 g / 100 ml of water at about 20 °C. For example, said (a3) at least one non-polymeric acyclic polyol may be present in the binder part a) in an amount of about 0 to about 10 wt.% based on the weight of the binder part a). In certain embodiments, said (a3) at least one non-polymeric acyclic polyol may be present in the binder part a) in a certain proportion to its component (a1). For example, based on the weight of component (a1), the binder part a) may contain 0-10 wt.%, 0-8 wt.%, 0-5 wt.% or 0-3 wt.% of said (a3) at least one non-polymeric acyclic polyol. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the values above, are expressly contemplated for use herein.

[0200] 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.

[0201] In another embodiment not mutually exclusive with the above, the binder part a) of the two-component (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, said (a4) at least one non-polymeric cycloaliphatic polyol may be present in the binder part a) in an amount of about 0 to about 10 wt.% based on the weight of the binder part a). In certain embodiments, said (a4) at least one non-polymeric cycloaliphatic polyol may be present in the binder part a) in a certain proportion to its component (a1). For example, based on the weight of component (a1), the binder part a) may contain 0-10 wt.%, 0-8 wt.%, 0-5 wt.% or 0-3 wt.% of (a4) at least one non-polymeric cycloaliphatic polyol. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the values above, are expressly contemplated for use herein.

[0202] Exemplary non-polymeric cycloaliphatic polyols that can be used alone or in combination include: 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanediethenol, 2,2-bis(4-hydroxycyclohexyl)propane, dihydro-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 includes 1,4-cyclohexanedimethanol.

[0203] Part b) Crosslinking agent

[0204] The crosslinking agent part b) of the compositions of the present invention includes at least one polyisocyanate compound having -NCO side groups. It is not excluded that the crosslinking agent part b) of the composition may further include other crosslinking compounds, such as melamine resins and blocked isocyanates, in addition to the polyisocyanate compound having -NCO side groups.

[0205] In two-component (2K) compositions, the molar ratio of active hydrogen atoms to -NCO groups is from about 5:1 to about 1:5, usually from about 3:1 to about 1:3. For example, the molar ratio of active hydrogen atoms to -NCO groups can be from about 2:1 to about 1:2 or from about 1.5:1 to about 1:1.5. The term "-NCO group" includes blocked -NCO groups, which are therefore also included in the term molar ratio. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0206] As used herein, "polyisocyanate" refers to a compound containing at least two -N=C=O functional groups, such as a compound containing 2 to 5 or 2 to 4 -N=C=O functional groups. Suitable polyisocyanates include aliphatic, cycloaliphatic, aromatic, and heterocyclic isocyanates, their dimers and trimers, and mixtures thereof.

[0207] Aliphatic and cycloaliphatic polyisocyanates can contain 6 to 100 carbon atoms, which are connected in a straight chain or in a ring and have at least two isocyanate-reactive groups. Examples of suitable aliphatic isocyanates include straight-chain isocyanates such as ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, triisocyanatenonane, 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 12MDI), 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), cyclohexane 1,4-diisocyanate, hydrogenated xylylene diisocyanate (H6XDI), 1-methyl-2,4-diisocyanato-cyclohexane, m- or p-tetramethylxylylene diisocyanate (m-TMXDI, p-TMXDI), and dimer fatty acid diisocyanate. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the values above, are expressly contemplated for use herein.

[0208] As used herein, the term "aromatic polyisocyanate" describes an organic isocyanate in which the isocyanate groups are directly attached to the ring of a mononuclear or polynuclear aromatic hydrocarbon group. A mononuclear or polynuclear aromatic hydrocarbon group refers to a substantially planar cyclic hydrocarbon moiety of conjugated double bonds, which may be a single ring or may include multiple fused (condensed) or covalently linked rings. The term aromatic also includes alkylaryl. Generally, in a ring, the hydrocarbon (main) chain includes 5, 6, 7, or 8 main chain atoms. Examples of such planar cyclic hydrocarbon moieties include cyclopentadienyl, phenyl, naphthyl-,

[10] annulenyl- (1,3,5,7,9-cyclododecapentaenyl),

[12] annulenyl-, [8]annulenyl-, pentalene (peri-naphthalene), 1,9-dihydropyrene, (chrysene) (1,2-benzophenanthrene). Examples of alkylaryl moieties include benzyl, phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-naphthylpropyl, 2-naphthylpropyl, 3-naphthylpropyl, and 3-naphthylbutyl.

[0209] Exemplary aromatic polyisocyanates include: all isomers of toluene diisocyanate (TDI), including pure isomers or mixtures 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; dialkyl and tetraalkyl diphenylmethane diisocyanates; dibenzyl 4,4'-diisocyanate; phenylene 1,3-diisocyanate; phenylene 1,4-diisocyanate; triphenylmethane triisocyanate; 1,3,5-benzenetriisocyanate; and 2,4,6-toluenetriisocyanate.

[0210] In use, the polyisocyanate can be biuretized, allophanated, and / or isocyanurated by generally known methods. During use, these derivatives can be substantially free of the parent diisocyanate: the derivatives can be separated from any excess parent diisocyanate by conventional methods including but not limited to distillation.

[0211] It should also be noted that the term "polyisocyanate" includes hydrophilic prepolymers formed by the partial reaction of the above-mentioned aliphatic, cycloaliphatic, aromatic, and heterocyclic isocyanates with polyether polyols or polyester polyols to produce isocyanate-functional oligomers, which can be used alone or in combination with free isocyanates.

[0212] The term "polyisocyanate" also includes ionically modified isocyanate-functional compounds, such as ionically modified isocyanate-functional prepolymers. Ionically modified polyisocyanates contain at least two isocyanate groups and at least one ionic or ionizable group. In certain embodiments, anionically modified isocyanate-functional compounds, such as anionically modified isocyanate-functional prepolymers, can be included in crosslinker part b). In this regard, suitable anionic or ionizable groups include carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and their salts. Suitable bases for neutralizing the anionic groups to form such salts include: alkali metals such as Na and K; ammonium; and trialkylamines such as triethylamine and triisopropylamine.

[0213] Exemplary polyisocyanates that can be purchased from Covestro AG and used in the present disclosure include: N3900; Bayhydur 2487 / 1; Bayhydur 2700; Bayhydur 3100; Bayhydur 304; Bayhydur 305; Bayhydur 307; Bayhydur 2451 / 1; Bayhydur 2547; Bayhydur 2655; Bayhydur 2759; Bayhydur XP; Bayhydur 701-90; Bayhydur PGDA; and Bayhydur MPA / X.

[0214] Additives and auxiliary components

[0215] The compositions of the present disclosure may further comprise, or be free of, one or more adjuvants and additives that can impart better properties to these compositions and the coatings obtained therefrom. For example, the adjuvants and additives can impart one or more of the following properties: reduced darkness; increased image clarity (DOI); longer processing time to enable; faster curing time; lower residual tack; and improved leveling. These adjuvants and additives include: catalysts, plasticizers, stabilizers (including UV stabilizers), reactive diluents, desiccants or moisture scavengers, tackifiers, wetting agents, defoamers, flame retardants, rheology control agents, color pigments, dyes, effect pigments, co-solvents, and non-reactive diluents.

[0216] These adjuvants and additives can be used in the desired combinations and proportions, provided that they do not have an adverse effect on the properties and basic performance of the composition. Although there may be exceptions in some cases, these adjuvants and additives generally total 0 - 40 wt.%, for example 0 - 30 wt.%, of the total composition.

[0217] Generally, adjuvant materials and additives containing reactive groups can be blended into the appropriate part of a two-component (2K) composition to ensure its storage stability; non-reactive materials can be formulated into either part or both parts. For example, in certain embodiments, part b) of the crosslinker of the composition can be free of compounds containing active hydrogen atoms.

[0218] The composition may include one or more catalysts for the reaction of -NCO groups with active hydrogen compounds. Standard catalysts known in the art include: stannous carboxylates such as stannous octoate, stannous oleate, stannous acetate and stannous laurate; dialkyltin 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; alkoxides of tin (alkoxylates) such as dibutyltin dimethoxide, dibutyltin diphenoxide and dibutyltin diisopropoxide; oxides of tin such as dibutyltin oxide and dioctyltin oxide; reaction products of dibutyltin oxide and phthalates; mercaptostannanes; alkyl titanates; organoaluminum compounds such as aluminum triacetylacetonate, aluminum triethylacetoacetate and diisopropoxyaluminum ethylacetoacetate; chelates such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; organosilicon titanium compounds; bismuth tris(2-ethylhexanoate); acid compounds such as phosphoric acid and p-toluenesulfonic acid; triphenylborane; triphenylphosphine; 1,8-diazabicyclo[5.4.0]undec-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(tetramethylguanidino)naphthalene; and 2-tert-butyl-1,1,3,3-tetramethylguanidine.

[0219] Depending on the nature of the isocyanate, the amount of catalyst is typically from 0.005 to 2% by weight of the composition. For example, based on the weight of the composition, the composition may contain from 0.01 to 2 wt.% or from 0.01 to 1 wt.% of the catalyst. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above values, are expressly contemplated for use herein.

[0220] The addition of certain additives can promote the adhesion of the coating composition to a specific substrate. In this regard, based on the weight of the composition, the composition may contain from 0 to 5 wt.%, such as from 0.5 to 5 wt.%, of at least one additive selected from the following: morpholine (2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-benzopyran-4-one); 3,7-dihydroxy-2-naphthoic acid (3,7-dihydroxynaphthalene-2-carboxylic acid); pyrogallol carboxylic acid (2,3,4-trihydroxybenzoic acid); 3,4-dihydroxybenzoguanidine acetic acid; gallic acid (3,4,5-trihydroxybenzoic acid); para-aminosalicylic acid (4-amino-2-hydroxybenzoic acid, PAS); flutter 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.

[0221] As used herein, the term "pigment" refers to molecules that are insoluble in the liquid carrier and impart color or optical effects thereto.

[0222] In certain embodiments, the composition may comprise at least one color pigment. Color pigments useful herein may be organic or inorganic. Exemplary color pigments that may 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; pyrrole pigments; phthalocyanines (such as copper phthalocyanine blue and copper phthalocyanine green); quinacridones (such as quinacridone violet); quinophthalone pigments; dioxazine pigments; carbon black; azurite; aluminum silicate; potassium aluminum silicate; antimony oxide; barium metaborate; barium sulfate; cadmium sulfide; cadmium selenide; calcium carbonate; calcium metaborate; calcium metasilicate; chromium oxide; clay; copper oxide; copper oxychloride; feldspar; iron oxides such as yellow and red iron oxides; kaolinite; spodumene; magnesium silicate; nepheline syenite; silicates; sulfides; talc; titanium dioxide; ultramarine; zinc chromate; zinc oxide; and zinc phosphate.

[0223] In certain embodiments, the composition may comprise at least one effect pigment, which refers to a pigment that can exhibit an optical effect caused by non-absorption. Specific examples include graphite effect pigments, metallic effect pigments, and pearlescent pigments. The effect pigment may have at least one of the following properties: about 1 to about 60 m 2 / g, such as about 5 to about 50 m 2The specific surface area per g is measured by nitrogen adsorption according to the Brunauer-Emmett-Teller (BET) method; the average volume particle size (Dv50) is from about 1 to about 500 μm, such as from about 5 to about 100 μm, and is measured by laser diffraction. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values above, are expressly contemplated for use herein.

[0224] The metallic effect pigments can include acicular, spherical, oval, cylindrical, bead-shaped, cubic, plate-shaped or flake-shaped particles. Particles of different shapes can be used alone or in combination.

[0225] Exemplary metals that the metallic effect pigments can contain include: aluminum, copper, copper-zinc alloy, copper-tin alloy, stainless steel, carbon steel, iron, silver, zinc, nickel, titanium, chromium, manganese, vanadium, magnesium, and zinc-magnesium alloy. The constituent metals can be coated with one or more inert oxides to form the effect pigments. Exemplary metal oxides include: silica, 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. When present in the pigment, the thickness of these metal oxide layers is generally 20 - 400 nm, such as 50 - 400 nm or 50 - 250 nm. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0226] Pearlescent pigments include a transparent non-metallic plate-shaped substrate coated with at least one layer containing a metal oxide having a refractive index. In some embodiments, multiple layers of metal oxides are used, and the refractive indices of consecutive layers differ by at least about 0.1. In some embodiments, the pearlescent pigments have an interference color when observed on a black background.

[0227] Exemplary non-metallic plate-shaped substrates include: natural mica, synthetic mica, bismuth oxychloride, graphite, aluminum oxide, iron oxide mica, perlite, silica, borosilicate glass, glass, titanium dioxide-coated mica, and iron oxide-coated mica.

[0228] Exemplary metal oxides capable of forming one or more coating layers of pearlescent pigments include: silica, 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 individually, but is typically about 20 to about 400 nm, such as 50 - 400 nm or 50 - 250 nm. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values and numerical ranges described above, are expressly contemplated for use herein.

[0229] Rheology control agents optionally used in the compositions of the present invention can include fillers, thickeners, and combinations thereof. Based on the weight of the composition, the total amount of rheology control agent in the composition generally does not exceed 10 wt.%. For example, based on the weight of the composition, the composition can contain 0 - 8 wt.%, 0 - 5 wt.%, or 0 - 2 wt.% of the rheology control agent. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values described above, are expressly contemplated for use herein.

[0230] Exemplary thickeners include: clay thickeners such as organoclays; polysaccharides such as guar gum and xanthan gum; polyacrylates; and associative thickeners. Mention may be made of polysaccharide thickeners used as cellulose or cellulose derivatives, for example: carboxymethyl cellulose; methyl cellulose; hydroxyethyl cellulose; hydroxyethyl methyl cellulose; hydroxypropyl methyl cellulose; cellulose nanofibers; and cellulose nanocrystals.

[0231] Fillers can include particles that are needle-shaped, spherical, oval, cylindrical, bead-shaped, cubic, or plate-shaped, and can be used alone or in combination. In addition, aggregates of more than one particle type can also be used. The average volume particle size (Dv50) of the filler measured by laser diffraction is typically about 0.1 to about 1500 μm, such as about 1 to about 1250 μm. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values described above, are expressly contemplated for use herein.

[0232] Exemplary fillers include calcium carbonate, calcium oxide, calcium hydroxide (lime powder), precipitated and / or pyrogenic silica, zeolites, bentonite, wollastonite, magnesium carbonate, diatomaceous earth, barium sulfate, aluminum oxide, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass beads, glass powder, and other ground mineral substances. Organic fillers can also be used, especially wood fibers, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, chopped straw, bran, ground walnut shells, and other short cut fibers. Short fibers such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers, or polyethylene fibers can also be added.

[0233] When present, the BET specific surface area of the fumed silica and / or precipitated silica can be from about 10 to about 90 m 2 / g. When using these silicas, they not only do not cause any additional increase in the viscosity of the composition, but also contribute to enhancing the strength of the cured composition. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0234] It is also conceivable to use fumed silica and / or precipitated silica having a higher BET specific surface area, which is advantageously from about 100 to about 250 m 2 / g: Due to the larger BET specific surface area, only a smaller proportion (by weight) of silica is required to achieve the effect of enhancing the cured composition. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0235] Hollow spheres having a mineral shell or a plastic shell can also be used. For example, hollow glass spheres commercially available under the trademark Glass can be used. Plastic-based hollow spheres can also be used, such as or For example, they can comprise inorganic or organic substances, and each has an average volume particle size (Dv50) of 1 mm or less, typically 500 μm or less, as determined by laser diffraction.

[0236] Fillers that impart thixotropy to the composition can be typical for many applications. Such fillers are also referred to as rheological aids and include, for example, hydrogenated castor oil, fatty acid amides, and expandable plastics such as PVC.

[0237] For the purposes of the present disclosure, a "plasticizer" is a substance that reduces the viscosity of the composition and thus improves its processability. Herein, based on the total weight of the composition, the plasticizer can account for up to 10 wt.% or up to 5 wt.%, and the plasticizer is typically selected from the following substances: dicarbamates; monofunctional, linear or branched C4-C 16Ethers of alcohols, such as Cetiol OE (available from BASF); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid, and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-group-containing or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; phosphoric acid esters; sulfonic acid esters; trimellitic acid esters; polyether plasticizers, such as end-capped polyethylene or polypropylene glycol; polystyrene; hydrocarbon plasticizers; chlorinated paraffins; and mixtures thereof. It should be noted that phthalate esters can also be used as plasticizers in principle, but are not commonly used due to their potential toxicity.

[0238] For the purposes of the present disclosure, "stabilizer" shall be understood to mean an antioxidant, heat stabilizer, or hydrolysis stabilizer. Based on the total weight of the composition, the stabilizers herein can total up to 10 wt.% or up to 5 wt.%. Standard commercial examples of stabilizers suitable for use herein include: hindered phenols, thioethers, benzotriazoles, benzophenones, benzoates, cyanoacrylates, acrylates, amines of the hindered amine light stabilizer (HALS) type, phosphorus, sulfur, and mixtures thereof.

[0239] To further increase the shelf life, it is generally recommended to further stabilize the compositions of the present disclosure with desiccants to prevent moisture penetration. Examples of suitable desiccants or moisture-removing agents include: silica gel; anhydrous calcium sulfate (anhydrous gypsum); calcium sulfate dihydrate (gypsum); calcium oxide; montmorillonite clay; molecular sieves, such as molecular sieves including natural or synthetic zeolites; and activated alumina.

[0240] The softening point of the waxes having practical value in the present disclosure can be from about 50 to about 150 °C and can include one or more of the following: polyethylene having a number average molecular weight (Mn) of from about 500 to about 7500; petroleum waxes, such as paraffin wax and microcrystalline wax; synthetic waxes polymerized from carbon monoxide and hydrogen, such as Fischer-Tropsch wax; polyolefin waxes, including functionalized polyolefin waxes, such as maleated polyethylene, maleated polypropylene, and maleated poly(ethylene-co-propylene); and hydrogenated animal oils, fish oils, or vegetable oils. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the numerical values above, are expressly contemplated for use herein.

[0241] For certain applications, it may also be necessary to reduce the viscosity of the compositions according to the present disclosure by using a reactive diluent. Based on the total weight of the composition, the total amount of reactive diluent present is typically 0 - 10 wt.%, for example 0 - 5 wt.%. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0242] If cosolvents and non-reactive diluents can effectively adjust the viscosity of the compositions of the present disclosure, the presence of cosolvents and non-reactive diluents in the compositions is not excluded. For example, by way of illustration only, the compositions can include 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 methoxypropyl acetate (MPA); alkyl propionate solvents such as n-butyl propionate and n-pentyl propionate; diesters such as dimethyl succinate, dimethyl glutarate, 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 monon-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl 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 such as dimethylacetamide and N-methylpyrrolidone; ketone solvents such as acetone, diisobutyl ketone, isobutyl heptyl ketone, isophorone, methyl ethyl ketone, methyl n-pentyl ketone, and methyl isobutyl ketone; toluene; xylene; diphenylmethane; diisopropylnaphthalene; petroleum fractions such as products (available from Exxon); and chlorinated hydrocarbon solvents such as 4-chlorobenzotrifluoride and 3,4-bis(dichloro)benzotrifluoride.

[0243] Any cosolvent or non-reactive diluent in the two-component (2K) composition need not be added separately to any one or more of the components or to the composition itself. Alternatively, one or more of the components of the composition can be provided in the cosolvent or diluent. In certain embodiments, any solvent or diluent included in part b) of the crosslinker of the composition can be free of active hydrogen atoms.

[0244] Typically, the total of the cosolvents and non-reactive diluents is less than 5 wt.%, particularly less than 1 wt.%, based on the total weight of the composition. Excluding at least part of these cosolvents and non-active diluents enables the volatile organic compound (VOC) content of the two-component (2K) water-based composition to be at most about 420 g / l, such as at most about 360 g / l, such as at most about 300 g / l, or even at most about 240 g / l when measured according to ISO 11890-2:2006. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0245] Methods and Applications

[0246] For two-component (2K) curable compositions, the reactive parts are brought together and mixed in a manner that causes them to harden. The reactive compounds can be mixed under sufficient shear force to produce a homogeneous mixture. This can be achieved without special conditions or special equipment. That is, suitable mixing equipment can include: static mixing equipment; magnetic stir bar devices; whisking equipment; augers; batch mixers; planetary mixers; C.W. Brabender or type mixers; and high-shear mixers such as blade-style blenders and rotary impellers. In some embodiments, once the reactive parts are mixed, one or more of water, co-solvents, non-reactive diluents can be added under stirring to adjust the viscosity of the composition.

[0247] For small-scale applications where the volume used is less than 2 liters, typical packaging of the two-component (2K) composition is side-by-side or coaxial cartridges, where two tubular chambers are arranged side-by-side or nested and sealed with pistons: actuation of these pistons allows the parts to be extruded from the cartridges, advantageously through a closely mounted static or dynamic mixer. For larger-volume applications, the two parts of the composition can be advantageously stored in drums or pails: in this case, the two parts are extruded by a hydraulic press, in particular by a follower plate, and fed via a pipeline to a mixing device that can ensure fine and highly homogeneous mixing of the hardener and the binder part. The binder part is typically sealed with an airtight and moisture-proof seal strip, whereby both parts can be stored for a long time, ideally for 12 months or longer.

[0248] Non-limiting examples of dispensing devices and methods suitable for the two-component of the present disclosure include those described in U.S. Patent No. 6,129,244 and U.S. Patent No. 8,313,006, and in various non-limiting embodiments, each patent is hereby expressly incorporated by reference.

[0249] More typically, the above composition is applied to the desired surface and then cured in situ. Before applying the composition, it is often advisable to pretreat the relevant surface to remove foreign matter therefrom. If applicable, this step can promote subsequent adhesion of the composition to the surface. Such treatment methods are well known in the art and can be carried out in a single-stage or multi-stage manner.

[0250] In some embodiments, adhesion of the coating composition to an optionally pretreated substrate surface can be promoted by applying a primer to the substrate surface. A primer composition may be necessary to ensure effective fixation and / or curing time of the binder composition on an inert substrate.

[0251] It is not excluded to provide other intermediate layers between the primer and the coating composition of the present disclosure, and multi-layer coatings will be described below.

[0252] Typically, the composition is applied to the desired surface of the substrate by conventional application methods such as: brushing; rolling; knife coating; printing methods; and spraying methods, including but not limited to air atomization spraying, air-assisted spraying, airless spraying, and high volume low pressure spraying.

[0253] These compositions can be applied to the surface with a wet film thickness of about 10 to about 500 μm. Applying thinner coatings within this range is more economical and can reduce the likelihood of harmful thick cured areas. However, when applying thinner coatings or layers, control must be exercised to avoid forming discontinuous cured films. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0254] Curing of the applied composition is typically carried out at a temperature of about 20 to about 200 °C, typically at a temperature of about 20 to about 160 °C. The appropriate temperature depends on the specific compounds present and the desired curing rate, which can be determined by those skilled in the art according to the specific circumstances, and simple preliminary tests can be carried out if necessary. For example, in vehicle production line applications, curing temperatures of about 80 to about 160 °C or about 100 to about 140 °C can be effective. Conversely, for repair applications, curing temperatures of about 20 to about 80 °C or about 40 to about 60 °C can be effective. For applications on large vehicles and transportation means (such as trucks, buses, and train carriages), curing temperatures of about 20 to about 80 °C can be used. Of course, curing at lower temperatures within the above range is advantageous because it eliminates the requirement for significant heating or cooling of the mixture from the ambient temperature that is usually prevalent. However, where applicable, conventional means including baking and microwave induction can be used to raise the temperature of the mixture formed from the various elements of the composition above the mixing temperature and / or the application temperature. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0255] The present disclosure also provides an article comprising: a metal substrate; and a multi-layer coating disposed on the metal substrate, wherein at least one layer of the multi-layer coating comprises a cured composition as described herein. Although it is not excluded to use the cured composition as an undercoat (such as a primer or sealant) in the multi-layer coating, the cured coating composition is more suitable for use as or as: a solid color basecoat layer; a solid color topcoat; and / or a clear coat. For example, the cured coating composition can be used as or as a clear varnish coating.

[0256] The appended Figure 1 Figure 1 shows an exemplary article. The shown article (1) includes: a metal substrate (10); and a multi-layer coating (11) disposed on the metal substrate, wherein the multi-layer coating (11) includes: a primer layer (110) disposed on the metal substrate; a basecoat layer (120) that includes compounds imparting color and / or visual effects, wherein the basecoat layer is disposed on the primer layer (110); and a clearcoat layer (130) that includes a cured product of the above-mentioned two-component (2K) composition and is disposed on the basecoat layer (120).

[0257] Generally, the primer layer (110) is applied to promote adhesion between the substrate surface and subsequent coating layers. Moreover, the primer coating layer can be used to enhance the physical properties of the entire coating system, particularly its corrosion resistance and impact strength. In addition, the primer coating layer can improve the overall appearance of the coating system by providing a smooth layer on which subsequent layers can be applied.

[0258] Figure 1 In Figure 1 , the primer layer (110) is depicted as being disposed on and in direct contact with the metal substrate (10). However, it should be understood that one or more intermediate coating layers can be provided between the metal substrate and the primer layer (110). Conversion coating layers are representative examples of such intermediate coating layers. The term "conversion" herein refers to the treatment of the substrate surface that results in the surface material being chemically converted into a different material. Generally, the surface of a metal or alloy substrate is chemically treated to provide a tightly adhering conversion coating that consists entirely or in part of a stable form (e.g., an oxidized form) of the substrate metal. Such chemical conversion coatings can exhibit high corrosion resistance and provide a strong binding affinity for the subsequent primer layer (110).

[0259] Figure 1 The depiction of a single primer layer (110) in Figure 1 is for illustrative purposes only. However, in certain embodiments, multiple primer layers (110) can be present. Whether the primer is applied in a single layer or multiple layers, the total thickness of the at least one primer layer can typically be from about 10 to about 200 microns, such as from about 10 to about 150 microns, from about 10 to about 75 microns, or from about 20 to about 75 microns. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0260] Figure 1 The basecoat layer (120) of Figure 1 contains compounds imparting color and / or visual effects and is disposed on the primer layer (110). When the primer is applied in multiple layers, the basecoat layer is disposed on the topmost primer layer relative to the surface of the metal substrate (10).

[0261] Figure 1 The depiction of a single primer surfacer layer (120) is for illustrative purposes only. However, in certain embodiments, there may be multiple primer surfacer layers (120). The lowermost of these primer surfacer layers may be disposed on and in direct contact with the primer layer (110). Whether the primer surfacer layer is applied in a single layer or multiple layers, the total thickness of the at least one primer surfacer layer is typically about 5 to about 100 microns, such as about 5 to about 50 microns, about 5 to about 40 microns, or about 5 to about 30 microns. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0262] In Figure 1 the clearcoat (130) comprises the cured product of the above-described two-component (2K) composition and is disposed on the primer surfacer layer (120). When the primer surfacer layer is applied in multiple layers, the clearcoat (130) will be disposed on the uppermost primer surfacer layer relative to the surface of the metallic substrate (10). The clearcoat (130) generally has good chemical resistance as well as resistance to mechanical abrasion and weathering. In addition, the clearcoat (130) will have satisfactory optical properties, including transparency and gloss.

[0263] Similarly, Figure 1 the depiction of a single clearcoat (130) is for illustrative purposes only. However, in certain embodiments, there may be multiple clearcoats (130). The lowermost of these clearcoats may be disposed on and in direct contact with the primer surfacer layer (120). Whether the clearcoat is applied in a single layer or multiple layers, the total thickness of the at least one clearcoat is typically about 10 to about 500 microns, such as about 10 to about 200 microns, about 20 to about 100 microns, or about 30 to about 90 microns. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0264] In certain embodiments, the clearcoat or each clearcoat (130) of the article may be at least substantially transparent to visible light. Thus, for example, as measured by the transmittance (T R ) measurement method in accordance with ASTM D1746 (2023), the transmittance of the clearcoat or each clearcoat to visible light may be at least about 85%, at least about 90%, or at least about 95%.

[0265] The appended Figure 2Another exemplary article is shown. The article (1) shown includes: a metal substrate (20); and a multi-layer coating (21) disposed on the metal substrate, wherein the multi-layer coating (21) includes: a primer layer (210) disposed on the metal substrate; a basecoat layer (220) including a compound that imparts color and / or visual effect, wherein the basecoat layer is disposed on the primer layer (210); a tie layer (225) disposed on the basecoat layer (220); and a clearcoat layer (230) including a cured product of the above-mentioned two-component (2K) composition and disposed on the tie layer (225).

[0266] The tie layer (225) can be inserted between the basecoat layer (220) and the clearcoat layer (230) and can enhance the adhesion therebetween. Due to the presence of this insertion, the tie layer (225) is generally substantially transparent to visible light. Thus, for example, as measured by the transmittance (T R ) measurement method in accordance with ASTM D1746 (2023), the transmittance of the tie layer (225) to visible light can be at least about 85%, at least about 90% or at least about 95%. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values, are expressly contemplated for use herein.

[0267] Figure 2 The depiction of a single tie layer (225) is for illustrative purposes only. However, in certain embodiments, there can be multiple tie layers (225). The lowermost of these tie layers can be disposed on the basecoat layer (220) and in direct contact therewith; in these embodiments, the clearcoat layer (230) including the cured product of the above-mentioned two-component (2K) composition will be disposed on the uppermost layer of the tie layer (225) and in direct contact therewith. In an embodiment, the total thickness of the at least one tie layer can be less than the total thickness of the clearcoat layer (230). Alternatively or additionally, the total thickness of the at least one tie layer can be from about 1 to about 50 microns, such as from about 1 to about 25 microns, from about 5 to about 25 microns or from about 5 to about 20 microns. In various non-limiting embodiments, all numerical values and numerical ranges, including integers and fractions, including and between the above numerical values and numerical ranges, are expressly contemplated for use herein.

[0268] A process for forming a multi-layer coating generally includes the following steps: i) providing a metal substrate; ii) applying a first curable coating composition of a first layer onto the metal substrate and making direct contact; iii) at least partially curing the first layer; iv) applying a second curable coating composition of a second layer onto the at least partially cured first layer and making direct contact; v) at least partially curing the second layer; vi) applying a third curable coating composition of a third layer onto the at least partially cured second layer and making direct contact; and, vii) at least partially curing the third layer. In an iterative process, steps vi) and vii) can be carried out and repeated in order to provide a fourth layer and other layers on the metal substrate. Regarding Figure 1 and Figure 2 For the multi-layer coating shown in

[0269] The metal substrate provided in step i) can generally be pretreated before step ii). Such pretreatment can include at least one of the following: cleaning the surface of the metal substrate; grinding the surface of the metal substrate; applying an anti-corrosion coating to the metal substrate; or, applying a conversion coating to the metal substrate, as described above.

[0270] Cleaning is used to remove foreign substances from the surface of the metal substrate. Cleaning processes are known in the art and can be carried out in a single-stage or multi-stage manner. For example, one or more of the following can be used: etching with an acid suitable for the substrate and optionally an oxidizing agent; ultrasonic treatment; 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, usually with deionized water or softened water. In the case of using an aqueous alkaline degreasing bath, any residual degreasing agent on the surface can generally be removed by rinsing the substrate surface with deionized water or softened water.

[0271] Irrespective of the cleaning of the substrate, the surface of the metal substrate (10) can be polished. Polishing generally includes sanding. For example, sanding can be carried out using an orbital sander with sandpaper of a predetermined grit size. After surface polishing, the metal substrate can optionally be cleaned to remove any dust or any other acquired dirt or contaminants generated during the polishing operation.

[0272] As used in the methods of the present disclosure, the term "at least partially cured" means that the curing of the curable coating composition has begun and, for example, crosslinking of the components of the composition has begun. The term encompasses any amount of curing after application of the curing conditions, from the formation of a single crosslink to a fully crosslinked state. The rate and mechanism of curing of the coating composition depend on various factors, including its components, the functional groups of the components, and the curing condition parameters.

[0273] At least partial solidification of a given coating layer generally indicates curing or drying. However, drying and curing can both be indicated in other ways, including, for example, a change in the viscosity of the coating layer, an increase in the temperature of the coating layer, and / or a change in the transparency / opacity of the coating layer.

[0274] Steps iv) and vi) of the above coating method can generally only begin when the at least partially cured or partially dried previous layer is able to substantially retain its shape after exposure to environmental conditions. "Substantially retain its shape" means that at least about 50% of the volume, more typically at least about 80% or about 90% of the volume, of the at least partially cured or dried layer retains its shape and does not flow or deform after 5 minutes of exposure to environmental conditions. In such a case, gravity generally does not have a substantial effect on the shape of the at least partially cured or partially dried layer after exposure to environmental conditions.

[0275] The shape of the at least partially dried or at least partially cured layer can generally affect whether the layer substantially retains its shape. For example, when the layer is rectangular or has other simple shapes, the at least partially cured or dried layer can be more resistant to deformation at an even lower level of curing or an even lower degree of drying than a layer with a more complex shape.

[0276] In certain embodiments, the application of each subsequent layer (step iv); step vi)) occurs before the at least partially cured layer reaches its final cured state, nominally when the layer is still "green" (uncured). In such embodiments, the application of the layers can be considered "wet-on-wet" such that adjacent layers are at least physically bonded to each other and can also be chemically bonded to each other. For example, the components of each layer in the first layer and subsequent layers may undergo chemical crosslinking / curing throughout the coating line, the effect of which can be beneficial to the life, durability, and appearance of the finished product. The difference between the partially cured and the final cured state is whether the partially cured layer can be further cured or crosslinked. This does not actually exclude the presence of functional groups in the final cured state, but due to steric hindrance or other factors, these groups can remain unreacted.

[0277] During the above iterative process, the thickness, width, shape, and continuity of each layer can be independently selected such that the previous layer and the subsequent layer can be the same as or different from each other in one or more of these aspects. For example, a given subsequent layer can only contact a part of the exposed surface of the at least partially cured or dried previous layer: the subsequent layer can be selectively constructed on the coating layer according to the desired shape of the coating layer.

[0278] The following examples illustrate the present disclosure and are not intended to limit the scope of the present disclosure in any way.

[0279] Examples

[0280] The following products were used in the examples below:

[0281]

[0282] Unless otherwise stated, all other compounds were obtained from Sigma Aldrich.

[0283] Synthesis Example 1 : Preparation of acrylic copolymer dispersion (AD1)

[0284] In a reactor equipped with a paddle stirrer, thermometer, condenser, and monomer / initiator feed system, 200 g of CE10P and 90 g of ethoxypropanol were added 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 maintaining the contents at 150 °C. After the feed, the reactor contents were held for 30 minutes.

[0285] After this holding stage, 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 2.5 hours while maintaining the contents at 150 °C. After this addition was a rinsing step of the feed system with 5 g of ethoxypropanol. After the rinsing step, the reactor contents were held at 150 °C for 2 hours.

[0286] The reactor contents were cooled to 100 °C, and 100 g of ethoxypropanol was distilled off. 33 g of dimethylaminoethanol (DMEA) was added to the contents, with a theoretical acid value of 20.5 mg KOH / g, and this amount was corrected according to the measured acid value. The polymer blend was diluted with 865 g of water preheated to about 70 °C.

[0287] The measured properties of the resulting dispersion were as follows: solids content, 45.1 wt.%; viscosity, 3500 cP; acid value, 33.6 mg KOH / g; pH, 8.2. In the visual determination of stability, the resulting aqueous dispersion showed no sedimentation after storage at 60 °C for 4 weeks.

[0288] As determined by gel permeation chromatography (GPC) using polystyrene calibration standards in accordance with ASTM 3536, the molecular weights of the synthesized copolymer were: number average molecular weight (Mn) of 4500 daltons; weight average molecular weight (Mw) of 27500 daltons.

[0289] Synthesis Example 2 : Preparation of polyester polyol (PE1) solution

[0290] A mixture of 911 g of trimethylolpropane, 748 g of hexahydrophthalic anhydride, and 138 g of dimer fatty acid (EmpolS) 1008 obtained from Henkel was heated to 250 °C. Esterification was carried out and water was separated until the resulting acid value was less than 5 mg KOH / g. After cooling the reaction mixture to below 125 °C, the solids content was adjusted to 70 wt.% with 90 g of xylene and 641 g of methoxypropyl acetate.

[0291] The calculated hydroxyl value of the resulting polyester polyol was 345 mg KOH / g, and the acid value was 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 in accordance with ASTM 3536 was 920 daltons.

[0292] Example 1

[0293] The above dispersions (AD1, PE1) were used to prepare two-component (2K) clear coating compositions. The binder part a) of the two-component composition was obtained by mixing the components given in Table 1 below. Similarly, the crosslinker part b) of the two-component composition was obtained by blending in the indicated amounts N 3900, Bayhydur XP2655, and solvents. The table details the preparation of the following: reference coating composition 1 (RCC1); and two coating compositions (CC1 - CC2) of the present disclosure.

[0294] Table 1

[0295]

[0296]

[0297] Mix the corresponding parts a) and b) given above in a weight ratio of 100:35 (a:b) to form coating compositions (RCC1, CC1-CC2), where the molar ratio of active hydrogen atoms to -NCO groups (here OH / NCO) in each composition is from 0.7:1 to 1.4:1. Adjust the viscosity of each composition to a viscosity of about 20 to 28 cps with deionized water, which is measured at room temperature using a Brookfield CAP2000 viscometer (400 rpm, No. 4 rotor). Spray the thus-obtained transparent coating compositions separately onto blackened steel plates and bake at 60 °C for 30 minutes. Then conduct the following evaluation tests on the obtained coatings, and the results are provided in Table 2 below.

[0298] Wave scan : The wave scan is designed to simulate visual perception and is performed using a Wavescan-DOI from BYK-Gardner GmbH. This instrument provides a laser point light source that irradiates the specimen at a 60° angle: the associated detector measures the reflected light intensity at equal but opposite angles. Mathematical filtering functions are used to separate the long-wave signal (structural size > 0.6 mm) and the short-wave signal (structural size < 0.6 mm) from the measured signal respectively. The measuring instrument rolls on the surface and measures the optical profile of the surface point by point within a specified distance. The long-term waviness value provided in Table 2 represents the variance of the long-wave signal amplitude and has been normalized to a dimensionless value within the range of 0 to 100, where 0 represents the minimum variance (best) and 100 represents the maximum variance (worst). Similarly, the short-term waviness value represents the variance of the short-wave signal amplitude and has been normalized to a dimensionless value within the range of 0 to 100, where 0 represents the minimum variance (best) and 100 represents the maximum variance (worst).

[0299] Image definition (DOI) : This is a measure of the clarity and distinctness of the reflected image in the applied coating and is determined using ASTM D5767 - 180, the standard test method for instrumentally measuring the distinctness of image (DOI) of a coated surface. The grade values obtained using the measurement procedure of this test method range from 0 to 100, and the value 100 represents a perfect DOI (clear image). As the value decreases from 100, the image becomes more distorted.

[0300] Jacksonville etch grade:Five (5) steel plates (30 cm x 30 cm) coated with a transparent coating were placed in an exposure site on Blount Island, Jacksonville, Florida, USA to determine the etching grade of the transparent coating. The exposure time lasted from the end of May to the end of August. Defects were rated on a scale of 1 (no visible etching) to 10 (severe etching), as detailed in GM Material Specification 9984157 (2009). The grades of the five replicate tests for each transparent coating were averaged to obtain the etching grade values provided in Table 2 below.

[0301] Table 2

[0302] Test performance RCC1 CC1 CC2 Image definition (DOI) 95.5 96.5 96.5 Long-term fluctuation value 4 4.8 1.7 Short-term fluctuation value 2.4 2.2 1.6 Jacksonville etch grade 7.5 6.4 6.6

[0303] As reflected by the lower short-term fluctuation values and higher DOI values given in Table 2, compared with Reference Coating Composition 1, the addition of a polyester resin to CC1 resulted in an improved appearance. In addition, CC1 exhibited better corrosion resistance in Jacksonville.

[0304] The combination of low molecular weight diol and polyester resin in Coating Composition CC2 is beneficial for the improvement of long-term and short-term fluctuation values without compromising the clarity of the image results or significantly impairing the corrosion resistance.

[0305] It will be understood that various changes and modifications of the exemplary embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the subject matter of the present invention and without diminishing its expected advantages. Accordingly, it is intended that such changes and modifications be covered by the appended claims. In addition, it will be understood that the features of the dependent claims can be embodied in the compositions and methods of each independent claim.

[0306] Once having benefited from the teachings of the foregoing description, those skilled in the art to which this disclosure pertains will conceive of many modifications of the disclosure and other embodiments listed herein. Accordingly, it is to be understood that the disclosure is not limited to the specific embodiments disclosed, and that these modifications and other embodiments are intended to be included within the scope of the appended claims.

Claims

1. A two-component (2K) waterborne coating composition, comprising: Water; a) A binder portion, which comprises: (a1) At least one hydroxy-functional (meth)acrylate copolymer; And (a2) At least one non-aromatic polyester having an active hydrogen group; and b) A crosslinker portion, which comprises: At least one polyisocyanate compound having an -NCO side group, wherein the number average molecular weight (Mn) of the non-aromatic polyester (a2) is from about 500 to about 5000 daltons, the acid value is from about 0 to about 30 mg KOH / g, the calculated hydroxyl value is from about 100 to about 600 mg KOH / g, and the calculated hydroxyl functionality is from about 2 to about 8; and wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is from 5:1 to about 1:

5.

2. The coating composition according to claim 1, wherein the weight ratio of the solids of (a1) to the solids of (a2) is from about 100:1 to about 100:

35.

3. The coating composition according to claim 1 or claim 2, having a volatile organic compound (VOC) content of at most about 420 g / l, measured according to ISO 11890-2:2006.

4. The coating composition according to any one of claims 1-3, wherein the hydroxy-functional (meth)acrylate copolymer is prepared by a two-step polymerization process from a monomer mixture.

5. The coating composition according to claim 1, wherein the (meth)acrylate copolymer is the reaction product of monomers in a monomer mixture which, based on the total weight of the monomers, comprises: About 10 wt.% to about 80 wt.% of i) at least one hydroxy-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid; About 0 wt.% to about 40 wt.% of ii) at least one hydroxy-functional unsaturated monomer different from component i); About 1 wt.% to about 8 wt.% of iii) at least one unsaturated acid-functional monomer; and About 0 wt.% to about 70 wt.% of iv) at least one polymerizable unsaturated monomer different from i), ii) and iii); wherein the (meth)acrylate copolymer is prepared by a bias-feed polymerization process using at least two feed streams; wherein one feed stream comprises: I) i) which accounts for about 60 to about 100% by weight of the total amount of i) in the monomer mixture; II) ii) which accounts for about 0 to about 60% by weight of the total amount of component ii) in the monomer mixture; III) iii) which accounts for about 0 to about 30% by weight of the total amount of iii) in the monomer mixture; and IV) iv) which accounts for 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 contain the balance of i)-vi).

6. The coating composition according to claim 5, wherein the monomer mixture comprises: About 20 to about 60% by weight of i); About 10 to about 30% by weight of ii); About 2 to about 6% by weight of iii); and About 20 to about 60% by weight of iv).

7. The coating composition according to claim 6, wherein, based on the total weight of the monomers in the monomer mixture, the monomer mixture comprises: from about 20 wt.% to about 60 wt.% of iv-1) at least one (meth)acrylate monomer represented by formula MA: H2C=CG a CO2R a (MA) Wherein: G a is hydrogen, a halogen or a methyl group; and R a is: C1-C 18 alkyl; C2-C 18 heteroalkyl; C3-C 18 cycloalkyl; C2-C8 heterocycloalkyl; C2-C8 alkenyl; or C2-C8 alkynyl; from about 0 wt.% to about 15 wt.% of iv-2) at least one vinyl aromatic monomer; and optionally from about 0 wt.% to about 25 wt.% of iv-3) at least one other polymerizable unsaturated monomer different from iv-1) and iv-2).

8. The coating composition according to claim 7, wherein in formula MA: R a is C1-C 18 alkyl or C3-C 18 cycloalkyl.

9. The coating composition according to claim 7, wherein the (meth)acrylate monomer of formula (MA) produces a homopolymer having a glass transition temperature (Tg) greater than about 30 °C upon homopolymerization.

10. The coating composition according to claim 7, 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, dicyclopentadienyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, and mixtures thereof.

11. The coating composition according to claim 7, wherein the vinyl aromatic monomer of iv-2) has formula (VA): Wherein: R 1 is H or a C1-C4 alkyl group; Each R 2 is independently hydrogen or a C1-C4 alkyl group; Ar is unsubstituted phenyl or phenyl substituted with 1-5 substituents, wherein each substituent is independently halogen or C1-C4 alkyl; and n is an integer from 0 to 4.

12. The coating composition according to 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 1-5 substituents, wherein each substituent is independently halogen or C1-C4 alkyl; and n is 0 or 1.

13. The coating composition according to claim 11, wherein iv-2) comprises at least one 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.

14. The coating composition according to claim 5, 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, CO2H or CH2CO2H; R 5 is hydrogen, a halogen or a methyl group; A is -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH2C(O)N-, -C(O)N-, -CH2-, -O-C(O)-, -NHC(O)O-, -NHC(O)NH-, -C6H4(R 8 )-NH-C(O)-O-, -C6H4(R 8 )-NH-C(O)-NH-, -C(O)O-CH2-CH(CH2OH)-O-, -C(O)O-CH2-CH(CH2OH)-NH-, -C(O)O-CH2-CH2-CH(OH)-O-, -C(O)O-CH2-CH2-CH(OH)-NH-, -CH2-O-CH2-CH(CH2OH)-O-, -CH2-O-CH2-CH2-CH(OH)-O-, -CH2-O-CH2-CH(CH2OH)-NH-, or -CH2-O-CH2-CH2-CH(OH)-NH-; Each R 6 independently represents a C2-C4 alkylene group; [a] has a value of about 5 to about 100; R 7 is C1-C 30 alkyl, C1-C 30 hydroxyalkyl, C1-C3 aminoalkyl, C3-C 18 cycloalkyl, C2-C5 heterocycloalkyl, C2-C 20 alkenyl, C2-C 12 alkynyl, C6-C 18 aryl, C7-C 24 alkaryl or C7-C 24 aralkyl; and R 8 is -CH2- or -(C)(CH3)2-.

15. The coating composition according to claim 14, wherein: R 4 is H, methyl, CO2H or CH2CO2H; R 5 is hydrogen, a halogen or a methyl group; A is -CH2C(O)O- or -C(O)O-; Each R 6 independently represents a C2-C4 alkylene group; [a] has a value of about 10 to about 30; and R 7 is C6-C 30 alkyl, C6-C 30 hydroxyalkyl, C6-C 30 aminoalkyl, C3-C 18 cycloalkyl, C6-C 18 aryl, C7-C 18 alkaryl or C7-C 18 aralkyl.

16. The coating composition according to claim 14, wherein in formula AM1: R 4 is H, methyl, CO2H or CH2CO2H; R 5 is hydrogen, a halogen or a methyl group; A is -C(O)O-; Each R 6 independently is a C2-C3 alkylene group; [a] has a value of about 10 to about 30; and R 7 is C6-C 30 alkyl, C6-C 30 hydroxyalkyl or C6-C 30 aminoalkyl.

17. The coating composition according to claim 14, wherein the monomer having the formula AM1 is selected from: lauryl ethoxylate [a] (meth)acrylate, cetyl ethoxylate [a] (meth)acrylate, stearyl ethoxylate [a] (meth)acrylate, behenyl ethoxylate [a] (meth)acrylate, lauryl ethoxylate [a] itaconate, cetyl ethoxylate [a] itaconate, stearyl ethoxylate [a] itaconate, behenyl ethoxylate [a] itaconate, lauryl ethoxylate [a] maleate, cetyl ethoxylate [a] maleate, stearyl ethoxylate [a] maleate, behenyl ethoxylate [a] maleate, and mixtures thereof, wherein [a] represents the molar number of the ethoxylate, and the value is from about 10 to about 30.

18. The coating composition according to any one of claims 1-17, wherein the (a2) non-aromatic polyester has: a number average molecular weight (Mn) of about 500 to about 1500 daltons; an acid value of about 0 to about 30 mg KOH / g; a calculated hydroxyl value of about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of about 4 to about 8.

19. The coating composition according to any one of claims 1-18, wherein the (a2) non-aromatic polyester is obtained by a polycondensation reaction of: at least one hydroxyl-functional component (a2h); at least one carboxyl-functional component (a2c); and optionally at least one hydroxycarboxylic acid component (a2hc), wherein the polycondensation reaction uses a stoichiometric excess of hydroxyl groups over carboxyl groups.

20. The coating composition according to 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 3-6 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.

21. The coating composition according to claim 20, wherein the at least one dicarboxylic acid includes dimer fatty acid, and its content is about 5 to about 50 wt.% based on the weight of the carboxyl-functional component.

22. The coating composition according to any one of claims 1-21, wherein the 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 having a water solubility of less than about 6 g / 100 ml of water at about 20 °C, wherein the amount of (a3) present is at most about 10 wt.%, based on the weight of the binder part a).

23. The coating composition according to any one of claims 1-22, wherein the 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, The amount of (a4) present is at most about 10 wt.%, based on the weight of the binder portion a).

24. The coating composition according to any one of claims 1-23, wherein the polyisocyanate compound contains 2-5 -NCO functional groups.

25. The coating composition according to any one of claims 1-24, wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is from about 3:1 to about 1:

3.

26. A cured product obtained from the aqueous coating composition as defined in claim 1.

27. 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 according to claim 26.

28. The article according to claim 27, wherein the multilayer coating comprises:[[]] a primer layer disposed on and in direct contact with the substrate; at least one basecoat layer comprising a compound imparting color and / or visual effect, 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 according to claim 26, the clearcoat layer being disposed on and in direct contact with at least one basecoat layer.

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