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

Abstract

A two-part (2K) water-based coating composition containing: Water: a) a binder part comprising: (a1) a hydroxyl-functional (meth)acrylate copolymer; (a2) a non-aromatic polyester having active hydrogen groups; and b) a crosslinking part comprising a polyisocyanate compound with pendant -NCO groups, wherein the non-aromatic (a2) polyester has a number average molecular weight (Mn) of 500 to 5000 Daltons, an acid number of 0 to 30 mg KOH / g, a calculated hydroxyl number of 100 to 600 mg KOH / g and a calculated hydroxyl functionality of 2 to 8; and wherein the (a1) (meth)acrylate copolymer is the reaction product of a monomer mixture comprising: i) a hydroxyl-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid; (ii) an unsaturated hydroxyl-functional monomer different from component (i); iii) a monomer having an unsaturated acid function; and iv) a (meth)acrylate monomer of the formula H2C=CG a CO2R a (MA).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a two-part (2K) waterborne coating composition containing a binder portion and a crosslinker portion. The binder portion comprises a water-dilutable hydroxyl-functional (meth)acrylate copolymer and a polyester having active hydrogen groups. The crosslinker portion of the composition comprises at least one polyisocyanate compound having pendant -NCO groups. The coating composition can be used as a clearcoat composition used in vehicle refinishing or refinishing. GENERAL STATE OF THE ART

[0002] Automotive refinishing refers to compositions and methods used in the repair of a damaged automotive finish, typically, but not necessarily, a finish provided by the original equipment manufacturer (OEM). For example, the damaged automotive component may have a defective area(s) where previously applied coating layers have been at least partially removed, and such removal may, under certain circumstances, have exposed the bare substrates of the component. The repair work may therefore involve the repair or replacement of the entire damaged body panel, the repair of one or more coating layers disposed on the components, or a combination of both.The size of the defective area and the presence or absence of coating layers surrounding the defective area - which, if present, can serve as anchors for the repair coating compositions - often determine the type of work performed.

[0003] As regards the repair of coating layers, the refinishing process generally comprises the following sequential steps: sanding the surface to be repaired, applying at least one layer of a primer composition; optionally sanding the applied primer composition; applying at least one layer of a basecoat composition to achieve the desired visual appearance, such as the desired color, gloss or degree of image sharpness (DOI); and applying a clearcoat composition, which should be sufficiently transparent or translucent to allow the underlying coating layer(s) to be seen through it.

[0004] In the past, the coating compositions used in refinishing work—including clearcoat compositions—were solvent-based and therefore contained significant amounts of volatile organic compounds (VOCs). However, the use of such compounds is regulated. In the United States, for example, emission standards for volatile organic compounds are governed by Section 183(e) of the Clean Air Act (Act), and regarding enforceable emission levels for automotive refinishes, reference can be made to 42 United States Code (USC) §7511b(e) and 40 Code of Federal Regulations (CFR) Part 59 Subpart B.

[0005] Recently, the coatings industry has made significant progress in complying with state and federal VOC emissions regulations through the development of high-solids solvent-based and water-based coating compositions.

[0006] Water-based coating compositions—unlike existing solvent-based alternatives—can not only exhibit the desired wetting and leveling properties for refinishing applications, but can also be easily applied by users without requiring any modifications to existing application equipment. However, water-based compositions require drying to properly crosslink and cure. Given their boiling point, achieving water removal through flash drying can be challenging, as water removal traditionally requires quite stringent baking conditions, where air movement and humidity in the oven or drying booth must be carefully controlled.

[0007] Since drying waterborne compositions can be energetically demanding and delay the refinishing process, volatile organic co-solvents or diluents have been incorporated into such compositions to improve their drying properties. However, the presence of such co-solvents and diluents may be undesirable in the future if the aforementioned regulations regarding permissible VOC levels in automotive refinish compositions become more stringent.

[0008] It is therefore desirable to develop water-based coating compositions that exhibit comparable properties to their solvent-based predecessors. In particular, such water-based compositions should exhibit good leveling on the application surface and, after application, be dehydratable under moderate or low baking conditions. Furthermore, such compositions should exhibit suitable optical properties to facilitate their use in refinishing applications, particularly as clearcoat compositions.

[0009] Further advantageous features and properties of the various compositions will become apparent from the following detailed description and examples. SUMMARY

[0010] The disclosure provides a two-part (2K) water-based coating composition comprising: Water; a binder part comprising: (a1) at least one water-dilutable hydroxyl-functional (meth)acrylate copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups; and b) a crosslinking moiety comprising: at least one polyisocyanate compound with pendant -NCO groups wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is about 5:1 to about 1:5; wherein the (a2) non-aromatic polyester has a number average molecular weight (Mn) of about 500 to about 5000 Daltons, an acid number of about 0 to about 30 mg KOH / g, a calculated hydroxyl number of about 100 to about 600 mg KOH / g, and a calculated hydroxyl functionality of about 2 to about 8; and wherein the (a1) (meth)acrylate copolymer is the reaction product of monomers in a monomer mixture comprising, based on the total weight of the monomers: from about 20 to about 60 wt.% of i) at least one hydroxyl-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid; from about 10 to about 30 wt.% ii) of at least one hydroxyl-functional unsaturated monomer other than component i); from about 2 to about 6 wt.% iii) at least one unsaturated acid-functional monomer; and from about 20 to about 60 wt.% iv) of at least one (meth)acrylate monomer of the formula MA: H2C=CG a CO2R a (MA) where: G a represents hydrogen, halogen or methyl; and R a for: 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 to about 15 wt.% v) of at least one vinyl aromatic monomer; and from about 0 to about 20 wt.% vi) at least one polymerizable unsaturated monomer different from i) to v).

[0011] The disclosure further provides a cured product obtained from the two-part (2K) water-based coating composition.

[0012] The disclosure 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 an important 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 color and / or visual effect imparting compound, wherein a 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 a basecoat layer.

[0013] While aspects of the disclosure are described herein with specific embodiments, one or more of those embodiments may be implemented in or combined with any other embodiment, unless otherwise stated, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive unless otherwise stated, and their combinations are within the scope of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Various other objects, advantages and features of the disclosure will become apparent to those skilled in the art from the following discussion taken in conjunction with the accompanying drawings, in which: Fig. 1 is a side cross-sectional view of an article according to a first embodiment of the present disclosure; and Fig.2 is a side cross-sectional view of an article according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0015] The following detailed description is merely exemplary and is not intended to limit the present disclosure, its application, and uses. Furthermore, there is no intention to be bound by any theory presented in the prior art or the following detailed description.

[0016] Embodiments of the present disclosure generally relate to water-dilutable, hydroxyl-functional (meth)acrylate copolymers, compositions containing them, and methods for preparing them. For the sake of brevity, conventional techniques for preparing such polymers and compositions are not described in detail herein. Moreover, the various objects and method steps described herein may be incorporated into a more comprehensive method or process with additional steps or functions not described in detail herein. In particular, various steps in the preparation of such polymers and associated compositions are known, so for the sake of brevity, some conventional steps are only briefly described or omitted entirely without providing the known process details.

[0017] The polymers and compositions disclosed herein may suitably comprise, consist of, or consist essentially of the components, elements, and process limitations described herein. The exemplary embodiments disclosed herein may suitably be practiced in the absence of any element not specifically disclosed herein. DEFINITIONS

[0018] The term "consists essentially of" may describe various non-limiting embodiments that are free of one or more optional compounds described herein or one or more additives, solvents, polymers, resins, etc., not described herein but used in the art.

[0019] The term "about" can describe values of ± 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% in various embodiments. Furthermore, in various non-limiting embodiments, it should be noted that all numerical values provided herein, except for specific examples, are approximate values, with the endpoints or specific values being understood as "about" or "approximately" the stated values.

[0020] The molecular weights referred to in this specification are typically measured by gel permeation chromatography (GPC) using polystyrene calibration standards as per ASTM 3536.

[0021] As used herein, "acid number" is the mass of potassium hydroxide (KOH) in milligrams required to neutralize one gram of the specified composition. The acid number can be determined by potentiometric analysis.

[0022] The term "hydroxyl number" used here is defined as the mass in milligrams of potassium hydroxide required to neutralize the acetic acid absorbed during the acetylation of one gram of a chemical substance containing free hydroxyl groups. The hydroxyl number can be determined according to DIN 53240.

[0023] The term "active hydrogen atoms" refers to hydrogen atoms exhibiting activity according to the Zerewitinoff test as described by Kohlerin, J. Am. Chem. Soc., 49, 3181 (1927), which is expressly incorporated herein by reference in its entirety in various non-limiting embodiments. Active hydrogen atoms can be derived from hydroxyl, thiol, primary amine, secondary amine, and carboxyl groups.

[0024] The term softening point (°C) used herein with reference to waxes is the ring and ball softening point, which, unless otherwise specified, is measured in accordance with ASTM E28.

[0025] The viscosities of the compositions described here are measured, unless otherwise stated, using a Brookfield Model CAP2000 viscometer at standard conditions of 20°C and 50% relative humidity (RH). The viscometer is calibrated using hydrocarbon oils of known viscosities ranging from 1 to 10,000 centipoise. A set of RV spindles attached to the viscometer is used for calibration. Measurements of the coating compositions are taken using spindle No. 4 at a speed of 400 revolutions per minute for one minute until the viscometer is equilibrated. The viscosity corresponding to the equilibrium value is then calculated from the calibration.

[0026] Unless otherwise stated, the term "particle size" refers to the particle's largest axis. In the case of a generally spherical particle, the largest axis is the diameter.

[0027] The term "volume median particle size" (Dv50), as used herein, refers to a particle size where 50% of the volume of sampled particles is larger and 50% of the volume of sampled particles is smaller than the specified Dv50 value. Similarly, the term "Dv90," when used, refers to a particle size where 90% of the volume of sampled particles is smaller and 10% of the volume of sampled particles is larger than the specified Dv90 value. Particle size is determined here by laser diffraction using the Anton Paar Particle Size Analyzer (PSA) 1190.

[0028] Room temperature, as used herein, is 23°C plus or minus 2°C.

[0029] The term “ambient conditions” means the temperature and pressure of the environment in which the composition is located or in which a coating layer or the substrate of the coating layer is located.

[0030] For the purposes of the present disclosure, "two-part (2K) compositions" are understood to mean compositions in which a first part a) and a second part b) are stored in separate containers due to their (high) reactivity. The two parts are only mixed before or during use and then react, typically without additional activation, to form a bond and thus a polymeric network. Higher temperatures can be used here to accelerate the crosslinking reaction.

[0031] The term "water-dilutable (co)polymer," as used herein, refers to a (co)polymer present in the form of particles in water, where the particles are dispersed or suspended and generally stable against flocculation upon further dilution with water. In contrast to a water-soluble (co)polymer, a dilute solution (about 1 g / L) of a water-dilutable polymer exhibits scattering when analyzed using dynamic light scattering or another technique known in the field of particle analysis.

[0032] The term "clearcoat" is used here to refer to a coating layer within a multi-layer coating that is sufficiently transparent or translucent to allow the underlying coating layer(s) to be seen through. The term "clear" does not require absolute transparency or translucency.

[0033] The term "metallic," as used herein, refers to any type of metal, metal alloy, or mixture thereof. As used herein, the term "alloy" refers to a substance consisting of two or more metals, or of a metal and a non-metal, that are intimately combined, usually by fusion and dissolution in the melt.

[0034] As used herein, the term “catalytic amount” meant a substoichiometric amount of catalyst relative to a reactant, unless expressly stated otherwise.

[0035] As used herein, the term "radical initiator" refers to compounds that, upon exposure to sufficient energy—e.g., in the form of light or heat—decompose into uncharged moieties that each possess at least one unpaired electron. In particular, a thermal radical initiator generates free radicals upon activation by thermal energy, e.g., upon heating or irradiation in the infrared or microwave range.

[0036] All isomers and chiral options for each compound described herein are expressly intended for use herein in various non-limiting embodiments.

[0037] It is understood that the indices of the polymers are typically described as average values, since the synthesis of polymers typically results in a distribution of different individual molecules.

[0038] As used herein, the term "monomer" refers to a substance that can undergo a polymerization reaction to contribute constitutional units to the chemical structure of a polymer. The term "monofunctional," as used herein, refers to the possession of one polymerizable unit. The term "polyfunctional," as used herein, refers to the possession of more than one polymerizable unit.

[0039] The term "blocked," as used herein, refers to a compound that possesses a "blocking group" such that its reactive functionality is unavailable until the blocking group is removed or degraded. The blocking group can be selectively removed or degraded at an appropriate point in the synthesis sequence. The initiating event can include moisture, heat, or irradiation. Examples of blocked isocyanates include those that have co-reacted with phenol, methyl ethyl ketoxime, or ε-caprolactam.

[0040] The term "fatty acid," as used herein, is a monocarboxylic acid consisting of an aliphatic chain of 4 to 22 carbon atoms and a terminal carboxyl group (COOH). The fatty acid may be saturated or unsaturated, branched or unbranched, and may or may not contain one or more hydroxyl groups. Examples of fatty acids include: linoleic acid, oleic acid, stearic acid, palmitic acid, dihydroxystearic acid, linolenic acid, and eiconsanoic acid.

[0041] The term "dimer fatty acid" is interchangeable with "dimerized fatty acid" and generally refers to a compound containing two fatty acid subunits in which the respective fatty acid side chains are covalently linked to each other via a bond or linking group. Thus, a fatty acid dimer, as described herein, is a covalent fatty dimer. The dimer fatty acid may be a heterodimer or a homodimer and may be cyclic or non-cyclic. The term is intended to encompass derivatives of dimer fatty acids that possess carboxyl functional groups that behave essentially like dicarboxylic acids upon reaction with glycols and diols to form polyesters: these include esters and ester-forming reactive derivatives such as acid halides and anhydrides.

[0042] As used herein, "(meth)acrylic" is an abbreviation referring to "acrylic" and / or "methacrylic." The term "(meth)acrylamide" thus refers to both acrylamide and methacrylamide.

[0043] As used herein, “C1-C n -Alkyl" refers to a monovalent group or moiety with 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 to 18 carbon atoms that 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 substituted with one or more halogens. Where applicable for a particular moiety (R), tolerance for one or more non-halogen substituents within an alkyl group is described in the description.

[0044] The term “C1-C 18 -Hydroxyalkyl" as used herein refers to an HO-(alkyl) group having 1 to 18 carbon atoms, wherein the point of attachment of the substituent is via the oxygen atom and the alkyl group is as defined above.

[0045] An “alkoxy group” refers to a monovalent group represented by -OA, where A represents an alkyl group: non-limiting examples include a methoxy group, an ethoxy group, and an iso-propyloxy group. The term “C1-C 18 -Alkoxyalkyl", as used herein, refers to an alkyl group or moiety having an alkoxy substituent as defined above, wherein the moiety (alkyl-O-alkyl) has a total of 1 to 18 carbon atoms: Such groups include methoxymethyl (-CH2OCH3), 2-methoxyethyl (-CH2CH2OCH3), and 2-ethoxyethyl. Analogously, the term "C7-C 18 -Alkoxyaryl", as used herein, refers to an aryl group having an alkoxy substituent as defined above, wherein the moiety (aryl-O-alkyl) comprises a total of 7 to 18 carbon atoms.

[0046] The term “C2-C4 alkylene” as used herein is defined as a saturated, divalent hydrocarbon radical having 2 to 4 carbon atoms.

[0047] The term “C3-C 18 "Cycloalkyl" encompasses a saturated, mono- or polycyclic hydrocarbon group or moiety having 3 to 18 carbon atoms. In the present disclosure, such cycloalkyl groups or moieties may be unsubstituted or substituted with one or more halogens. Where applicable for a particular moiety (R), tolerance for one or more non-halogen substituents within a cycloalkyl group is indicated in the description. Examples of cycloalkyl groups include: cyclopropyl; cyclobutyl; cyclopentyl; cyclohexyl; cycloheptyl; cyclooctyl; adamantane; and norbornane.

[0048] As used herein, the term “C2-C 18-Alkenyl" refers to hydrocarbon groups or moieties having 2 to 18 carbon atoms and at least one ethylenically unsaturated moiety. The alkenyl group or moiety may be straight-chain, branched, or cyclic and may optionally be substituted with one or more halogens. Where applicable for a particular moiety (R), a tolerance for one or more non-halogen substituents within an alkenyl group will be indicated in the description. The term "alkenyl" also includes radicals with "cis" and "trans" configurations, or alternatively, "E" and "Z" configurations, as will be appreciated by those of ordinary skill in the art. Examples of C2-C 20-Alkenyl groups 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=CHCH2CH3; -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.

[0049] As used herein, “C6-C 18-Aryl" alone or as part of a larger moiety—as in "aralkyl group"—refers to monocyclic, bicyclic, and tricyclic ring systems where the monocyclic ring system is aromatic or at least one of the rings in a bicyclic or tricyclic ring system is aromatic. The bicyclic and tricyclic ring systems include benzofused 2-3 membered carbocyclic rings. In the present disclosure, these aryl groups may be unsubstituted or substituted with one or more halogens. Where applicable for a particular moiety (R), tolerance for one or more non-halogen substituents within an aryl group is noted in the description. Exemplary aryl groups include: phenyl; (C1-C4)alkylphenyl, such as tolyl and ethylphenyl; indenyl; naphthalenyl; tetrahydronaphthyl, tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl.

[0050] As used herein, "alkylaryl" refers to alkyl-substituted aryl groups or moieties, and "substituted alkylaryl" refers to alkylaryl groups or moieties additionally bearing one or more substituents as described above. As used herein, "aralkyl" further means an alkyl group or moiety substituted with an aryl radical as defined above.

[0051] The term "hetero," as used herein, refers to groups or moieties containing one or more heteroatoms, such as N, O, Si, and S. For example, "heterocyclic" refers to cyclic groups that have, for example, N, O, Si, or S as part of the ring structure. "Heteroalkyl," "heterocycloalkyl," and "heteroaryl" are alkyl, cycloalkyl, and aryl groups, as defined above, that contain N, O, Si, or S as part of their structure.

[0052] The term "non-polymeric" is used here to describe a compound that is not composed of repeating structural units. A non-polymeric compound can be considered a unique, single structural unit.

[0053] The term "non-aromatic," used here to refer to monomers, refers to a compound that does not possess an aromatic nucleus. The term is intended to encompass both aliphatic and cycloaliphatic compounds, which may be saturated or unsaturated, and in the latter case, contain non-aromatic carbon-carbon double bonds or carbon-carbon triple bonds. Non-aromatic polymeric compounds may be essentially free of aromatic nuclei in their backbone, so that the polymer may contain aromatic nuclei only due to technical impurities of aliphatic or cycloaliphatic monomer units.

[0054] The term “base,” as used herein, refers to a species capable of abstracting a proton in a polar or nonpolar solvent, or capable of donating a hydroxide anion (OH).

[0055] In various embodiments, the term "free from" describes embodiments containing less than about 5, 4, 3, 2, 1, 0.5, or 0.1 wt. % of the subject component, compound, moiety, functional group, element, or ion, using a suitable weight basis known to one of ordinary skill in the art. In other embodiments, the term "free from" describes embodiments containing about 0 wt. % of the subject component, compound, moiety, functional group, element, or ion.

[0056] The term “anhydrous”, as used here, is synonymous with the term “free of water”.

[0057] As already mentioned, the water-based composition comprises water and: a) a binder portion, and b) a crosslinker portion. The water may be present in an amount of 30 to 80 wt.%, based on the weight of the composition. For example, the water may be present in an amount of 35 to 70 wt.%, 40 to 60 wt.%, 45 to 55 wt.%, 45 to 52 wt.%, or 46 to 51 wt.%. At this water content, drying and coalescence of the composition—when applied to a substrate—is unlikely to require high energy and time expenditures. Compositions with this water content may, for example, be characterized by a viscosity of less than 500 centipoise, less than 200 centipoise, less than 100 centipoise, less than 50 centipoise, less than 40 centipoise, or even less than 30 centipoise, measured at room temperature.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0058] It is not necessary for water to be added to the two-part (2K) composition independently of one or more components or the composition itself. Alternatively, one or more of the components of the composition can be provided in water.

[0059] In certain embodiments, the binder part a) of the two-part (2K) composition comprises water, such that the binder part a) provides at least a portion of the water of the two-part (2K) composition. However, it is not excluded that additional water is added to the composition during or after a binder part a) comprising water and the crosslinker part b) are brought together. The addition of this additional water can serve to reduce the viscosity of the composition, which can be useful for certain methods described below by which the composition is applied to substrates, such as spraying. PART A)

[0060] As regards the binder part a) of the two-part water-based composition, this part comprises the following: (a1) at least one water-dilutable hydroxyl-functional (meth)acrylic copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups.

[0061] The at least one hydroxyl-functional (meth)acrylate copolymer of component (a1) is water-dilutable but typically compatible with polyisocyanates, including hydrophobic polyisocyanates that have not been hydrophilically modified, including with polyether or polyester groups. Thus, the two-part coating composition itself is water-dilutable, which can offer the user flexibility in the application of the coating compositions, e.g., in vehicle refinishing work. Furthermore, the amount of vinyl aromatic monomers is believed to promote the miscibility of the hydroxyl-functional (meth)acrylate copolymer with the polyisocyanate, thereby maintaining the dispersion stability of this copolymer and providing a better appearance to the cured final coating.

[0062] The presence of the non-aromatic polyester in the binder portion of the composition improves the appearance of the resulting cured coatings. The non-aromatic polyester can also contribute to the weathering resistance of the cured coatings. Copolymer component (a1)

[0063] The (meth)acrylate copolymer is the reaction product of a monomer mixture which, based on the total weight of the monomers of the monomer mixture, comprises: from 20 to 60 wt.% of i) at least one hydroxyl-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid; from 10 to 30 wt.% ii) of at least one hydroxyl-functional unsaturated monomer different from component i); from 2 to 6 wt.% iii) at least one unsaturated acid-functional monomer; from 20 to 60 wt.% iv) of at least one (meth)acrylate monomer of the formula MA: H2C=CG a CO2R a (MA) where: G a represents hydrogen, halogen or methyl; and R a for: C1-C 18 -alkyl; C2-C 18 -Heteroalkyl; C3-C 18 -cycloalkyl-, C2-C8-heterocycloalkyl; C2-C8-alkenyl or C2-C8-alkynyl; from 0 to 15 wt.% v) of at least one vinyl aromatic monomer; and from 0 to 20 wt.% vi) at least one polymerizable unsaturated monomer different from the monomer components i) to v). Monomer component i): Hydroxyl-functional adduct

[0064] The monomer mixture comprises, based on the total weight of the monomers in the monomer mixture, 20 to 60 wt. % of i) at least one hydroxyl-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid. For example, the monomer mixture may comprise, based on the total weight of the monomers in the monomer mixture, 30 to 60 wt. % or 40 to 60 wt. % of i) of the at least one adduct. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0065] Typically, the adduct is formed by a nucleophilic addition reaction of the monoepoxy ester with the acid to form a hydroxyalkyl ester. This ring-opening acidolysis reaction usually requires a catalyst, with tertiary amines, quaternary ammonium compounds, and transition metal compounds being examples.

[0066] The monoepoxy ester reactants are typically glycidyl esters derived from aliphatic saturated monocarboxylic acids having a tertiary or quaternary carbon atom in the alpha (a) position. Representative monoepoxy ester reactants are the glycidyl esters of saturated α,α-dialkylalkane monocarboxylic acids having 5 to 13 carbon atoms or 9 to 11 carbon atoms in the acid molecule. Exemplary monoepoxy ester reactants include: versatic acid glycidyl ester, commercially available as Cardura E10 from Hexion; pivalic acid glycidyl ester, commercially available as Cardura E5 from Hexion; and the reaction product of a tertiary fatty acid having up to 12 carbon atoms and epichlorohydrin.

[0067] The acid-functional compound serving as reactant can be aliphatic unsaturated monocarboxylic acids, non-limiting examples of which include: α,β-monoethylenically unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; C1-C6 alkyl half esters of α,β-monoethylenically unsaturated dicarboxylic acids, such as fumaric acid and maleic acid; and C1-C6 alkyl esters of α,β-monoethylenically unsaturated tricarboxylic acids bearing a free carboxylic acid group. In various embodiments, acrylic acid and / or methacrylic acid are the acid-functional compound serving as reactant. Monomer component ii): Hydroxyl-functional ethylenically unsaturated monomer

[0068] The monomer mixture comprises, based on the total weight of the monomers in the monomer mixture, 10 to 30 wt. % ii) of at least one hydroxyl-functional monomer that is different from monomer component i). For example, the monomer mixture may comprise, based on the total weight of the monomers in the monomer mixture, 10 to 25 wt. % or 10 to 20 wt. % ii) of the at least one hydroxyl-functional monomer. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those mentioned above, are expressly intended for use herein.

[0069] Exemplary monomers of component ii) include hydroxyalkyl esters with primary and secondary hydroxyl groups derived from α,β-monoethylenically unsaturated monocarboxylic acids. These can include, for example, hydroxyalkyl esters derived from acrylic acid, methacrylic acid, crotonic acid, or isocrotonic acid.

[0070] In one embodiment, the monomer component ii) comprises at least one hydroxyl (meth)acrylate monomer of the formula HMA: H2C=CG a CO2R h (HMA) where: G a represents hydrogen, halogen or methyl; and R h for C1-G 18 -hydroxyalkyl.

[0071] Typical monomers according to the formula HMA are those where: G a represents hydrogen, halogen or methyl; and R h for C1-C 12 -hydroxyalkyl. Monomers in which G a represents hydrogen or methyl and R hstands for C1-C6 hydroxyalkyl, can also be used.

[0072] Examples of (meth)acrylate monomers according to the formula HMA are: hydroxyethyl (meth)acrylate; 1-hydroxypropyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; 1-hydroxybutyl (meth)acrylate; 2-hydroxybutyl (meth)acrylate; and 3-hydroxybutyl (meth)acrylate. Monomer component iii): Ethylenically unsaturated acid-functional monomer

[0073] The monomer mixture further comprises, based on the total weight of monomers in the monomer mixture, 2 to 6 wt.% of iii) at least one ethylenically unsaturated acid-functional monomer. For example, component iii) may comprise 2 to 5 wt.% or 2 to 4 wt.% of the monomer mixture. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0074] Without wishing to limit the present disclosure, the unsaturated acid-functional monomers can 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.

[0075] Typically, the 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 bearing at least one free carboxylic acid group; and mixtures thereof. In particular, the 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.

[0076] For the sake of completeness, it should be noted that although the unsaturated acid-functional monomer described above can be used in the form of the free acid, it is not excluded that the individual acid groups of the monomers are partially or completely neutralized with suitable bases, provided that this does not impair their participation in the copolymerization reaction. Monomer component iv): (meth)acrylate monomers of the formula MA

[0077] The monomer mixture also comprises, based on the total weight of the monomers in the monomer mixture, 20 to 60 wt.% iv) of at least one (meth)acrylate monomer of the formula MA: H2C=CG a CO2R a (MA) where: G a represents hydrogen, halogen or methyl; and R a for: C1-C 18 -alkyl; C2-C 18 -Heteroalkyl; C3-C 18 -cycloalkyl-, C2-C8-heterocycloalkyl, C2-C8-alkenyl or C2-C8-alkynyl.

[0078] For example, the monomer mixture may comprise, based on the total weight of the monomers in the monomer mixture, 25 to 50 wt.% iv) of the at least one (meth)acrylate monomer of formula MA. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0079] In typical monomers according to the formula MA, G a represents hydrogen, halogen or methyl; and R a stands for C1-C 18 -alkyl or C3-C 18 -Cycloalkyl. Monomers can also be used in which G a stands for hydrogen or methyl.

[0080] Examples of (meth)acrylate monomers according to the formula MA, which 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; dihydrodicyclopentandienyl (meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate; ethylene glycol monoethyl ether (meth)acrylate; Ethylene glycol monododecyl ether (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate; trifluoroethyl (meth)acrylate and perfluorooctyl (meth)acrylate.

[0081] The (meth)acrylate monomers forming component iv) of the monomer mixture may, in some embodiments, comprise "hard" monomers. The term "hard monomer" typically describes a monomer that, if homopolymerized, would yield a homopolymer with a glass transition temperature (Tg) greater than about 30°C. For example, monomer component iv) may comprise at least one (meth)acrylate monomer, which is considered a hard monomer.

[0082] Example hard monomers include: cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; dihydrodicyclopentandienyl (meth)acrylate; and 4-tert-butylcyclohexyl (meth)acrylate. Monomer component v): Optional aromatic vinyl monomers

[0083] The monomer mixture may also comprise, based on the total weight of the monomers in the monomer mixture, 0 to 15 wt. % v) of at least one vinyl aromatic monomer. For example, the monomer mixture may comprise, based on the total weight of the monomers in the monomer mixture, 4 to 14 wt. %, 8 to 14 wt. % or 10 to 14 wt. % v) of the at least one vinyl aromatic monomer. Alternatively, this monomer may be omitted entirely. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those mentioned above, are expressly intended for use herein.

[0084] In one embodiment, the monomer component v) comprises at least one vinyl aromatic monomer of the formula (VA): where: R 1 represents H or C1-C4 alkyl; every R 2 independently represents hydrogen or C1-C4 alkyl; Ar is unsubstituted phenyl or phenyl substituted by 1 to 5 substituents, each substituent independently being halogen or C1-C4 alkyl; and n is an integer from 0 to 4.

[0085] Typical monomers according to formula VA are those where: R 1 represents H or methyl; each R 2 independently represents H or methyl; Ar represents unsubstituted phenyl or phenyl substituted by 1 to 5 substituents, each substituent independently representing halogen or C1-C4 alkyl; and n represents 0 or 1.

[0086] Examples of vinyl aromatic monomers according 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. Monomer component vi): Optional additional monomers

[0087] The monomer mixture may also comprise, based on the total weight of the monomers in the monomer mixture, 0 to 25 wt.% of at least one polymerizable unsaturated monomer other than monomer components i) to v). For example, the monomer mixture may comprise, based on the total weight of the monomers in the monomer mixture, 0 to 20 wt.%, 1 to 20 wt.%, or 5 to 20 wt.% of the at least one polymerizable unsaturated monomer other than monomer components i) to v). In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0088] Exemplary monomers of component vi) which can be used alone or in combination include: aromatic (meth)acrylate monomers; (meth)acrylate-functionalized oligomers; nitrogen (N-)functionalized ethylenically unsaturated monomers; silane-functional ethylenically unsaturated monomers such as methacryloxypropyltri(C1-C5)alkoxysilanes and vinyltri(C1-C5)alkoxysilanes, acetoacetyl-functional unsaturated monomers such as acetoacetoxyethyl methacrylate; vinyl esters; vinyl and vinylidene halides; vinyl ethers; alkyl vinyl ketones; cycloalkyl vinyl ketones; heterocyclic aliphatic vinyl compounds; poly(meth)acrylates of alkane polyols; poly(meth)acrylates of oxyalkane polyols, and poly(C2-C3)alkylene glycol di(meth)acrylates.

[0089] Suitable aromatic (meth)acrylate monomers include those of the formula AII: H2C=CG b CO2R b (AII) where: G b represents hydrogen, halogen or methyl; and Rb for C6-C 18 -aryl, C1-C9-heteroaryl, C7-C 18 -Alkoxyaryl, C7-C 18 -Alkaryl or C7-C 18 -aralkyl.

[0090] Exemplary (meth)acrylate monomers according to formula (All) - which can be used alone or in combination - include: benzyl (meth)acrylate; phenoxyethyl (meth)acrylate; and phenoxypropyl (meth)acrylate.

[0091] Suitable (meth)acrylate-functionalized oligomers can be selected from (meth)acrylate-functionalized polyurethanes, (meth)acrylate-functionalized polybutadienes, (meth)acrylic polyol (meth)acrylates, polyester (meth)acrylate oligomers, polyamide (meth)acrylate oligomers, polyether (meth)acrylate oligomers, and mixtures thereof. The oligomers can have one or more acrylate and / or methacrylate groups bonded to the oligomeric backbone, wherein the functional (meth)acrylate groups can be located in a terminal position on the oligomer and / or distributed along the oligomeric backbone. It is typical for the (meth)acrylate-functionalized oligomer, which was reacted as a monomer in the derivation of the copolymer (a1), to have two or more (meth)acrylate functional groups per molecule; and / or has a weight average molecular weight (Mw) of about 300 to about 1000 Daltons.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0092] In the (N-)functionalized ethylenically unsaturated monomers, the nitrogen-functionalized groups can be either nitrile or urea or contain imide, amide or amine nitrogen atoms.

[0093] Example nitrile monomers include acrylonitrile and methacrylonitrile. Example hard maleimide monomers include: maleimide; methylmaleimide; ethylmaleimide; propylmaleimide; butylmaleimide; hexylmaleimide; octylmaleimide; dodecylmaleimide; stearylmaleimide; phenylmaleimide; and cyclohexylmaleimide.Beispielhafte (Meth)acrylamide beinhalten: Acryloylmorpholin-, Diaceton(meth)acrylamid; N-Methyl(meth)acrylamid; N-Ethyl(meth)acrylamid; N-Isopropyl(meth)acrylamid; N-tert-Butyl(meth)acrylamid; N-Hexyl(meth)acrylamid; N-Cyclohexyl(meth)acrylamid; N-Octyl(meth)acrylamid, N-tert-Octyl(meth)acrylamid, N-Dodecyl(meth)acrylamid, N-Benzyl(meth)acrylamid, N-(Hydroxymethyl)acrylamid, N-Isobutoxymethylacrylamid; N-Butoxymethylacrylamid; N,N-Dimethyl(meth)acrylamid, N,N-Diethyl(meth)acrylamid; N,N-Propyl(meth)acrylamid, N,N-Dibutyl(meth)acrylamid, N,N-Dihexyl(meth)acrylamid; N,N-Dimethylaminomethylacrylamid; N,N-Dimethylaminoethylacrylamid; N,N-Dimethylaminopropylacrylamid; N,N-Dimethylaminohexylacrylamid; N,N-Diethylamino-methylacrylamid, N,N-Diethylaminoethylacrylamid; N,N-Diethylamino-Propylacrylamid; N,N-Dimethylamino-Hexylacrylamid; N-Hydroxymethyl(meth)acrylamid; Acrylamido-2-methylpropansulfonat; und N,N'-Methylenbisacrylamid.

[0094] The inclusion of the residue of at least one amino(meth)acrylate monomer in the copolymer(s) (a1) is not excluded. As used herein, the term "amino(meth)acrylate" refers to a derivative of methacrylic acid or acrylic acid having a primary, secondary, or tertiary amino group. The amino group may be part of a linear, branched, or cyclic aliphatic group or an aromatic group. The at least one amino(meth)acrylate monomer may be a tertiary amino(meth)acrylate, such as, in particular, an N,N-dialkylaminoalkyl(meth)acrylate. In various embodiments, one or more of N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl methacrylate, or N,N-dimethylaminopropyl acrylate may be used.

[0095] In another non-limiting embodiment, the monomer mixture includes at least one vinyl monomer having a heterocyclic nitrogen structure. Exemplary heterocyclic structures are either 5- or 6-membered and may include oxygen atoms in addition to nitrogen. The 5- or 6-membered ring may be, for example, a pyridine, pyrimidine, pyridazine, imidazoline, imidazole, oxazoline, oxazole, or morpholine ring. Examples that may be used alone or in combination include: N-vinylcaprolactam (NVC); vinylmethyloxazolidinone (VMOX); N-vinylformamide; N-vinylcarbazole; N-vinylacetamide; and N-vinylpyrrolidone.

[0096] Exemplary vinyl esters that can be copolymerized in the present disclosure include vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and VEOVA™ series monomers available from Shell Chemical Company. Exemplary poly(meth)acrylates of alkane polyols that can be copolymerized include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, hexylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Exemplary poly(meth)acrylates of oxyalkane polyols that can be copolymerized include diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dibutylene glycol di(meth)acrylate, di(pentamethylene glycol) dimethacrylate.

[0097] In one embodiment, the monomer mixture comprises at least one monomer having the general formula AMI: R 4 -C(H) - C(R 5 )-A-(R 6 O) [a] -R 7 (AM1) where: R 4 represents H, methyl, CO2H or CH2CO2H; R 5 represents hydrogen, halogen or methyl; A for -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH2C(O)N-, -C(O)N-, -CH2-, -OC(O)-, -NHC(O)O-, - NHC(O)NH-, -C6H4(R 8 )-NH-C(O)-O-, -C6H4(R 8 )-NH-C(0)-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-; every R 6 independently represents C2-C4 alkylene; [a] has a value from 5 to 100; R 7 for 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 R 8 stands for -CH2- or -(C)(CH3)2-.

[0098] Typical monomers according to the formula AM1 are those where: R 4 represents H, methyl, CO2H or CH2CO2H; R 5 represents hydrogen, halogen or methyl; A represents -CH2C(O)O- or -C(O)O-; each R 6 independently represents C2-C4-alkylene; [a] has a value of 10 to 30; and R 7 for 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.

[0099] Representative monomers according to formula AM1 are those where: R 4 represents H, methyl, CO2H or CH2CO2H; R 5represents hydrogen, halogen or methyl; A represents -C(O)O-; each R 6 independently represents C2-C3-alkylene; [a] has a value of 10 to 30; and R 7 for C6-C 30 -Alkyl, C6-C 30 -hydroxyalkyl or C6-C 30 -Aminoalkyl.

[0100] Exemplary monomers according 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 number of moles of ethoxylation and has a value of 10 to 30. In other words, each of the above compounds can be described as an ethoxylated compound having a degree of ethoxylation of 10 to 30 moles of ethylene oxide. The parameter [a] may, in certain embodiments, have a value from 15 to 30 or from 15 to 25.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0101] The hydroxy-functional (meth)acrylic copolymers are typically prepared by radical solution copolymerization, in which a solution of the monomers is created in a solvent that is also capable of dissolving the copolymer, whereby the monomers are polymerized by radical polymerization, i.e., in the presence of the radical initiator. Generally, the above-mentioned monomers are added to a reflux reactor in the presence of at least one organic solvent and the radical initiator. The concentration of the monomers in the solution can vary, but a weight ratio of monomer to solvent of 1:20 to 2:1, for example, of 1:2 to 1.5:1, is typical. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those mentioned above, are expressly intended for use herein.

[0102] Typically, conventional polymerization conditions are used, including a temperature in the range of 25 to 250°C, e.g., 50 to 250°C or 75 to 250°C. The polymerization pressure is generally not critical, so the polymerization can be carried out at subatmospheric, atmospheric, or superatmospheric pressure. If necessary, the polymerization can be carried out in the absence of oxygen: the reaction vessel can be provided with an inert, dry gas blanket of, e.g., nitrogen, helium, and argon. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0103] Typically, the at least one free-radical initiator is used in an amount of 0.1 to 1 wt.%, for example, 0.1 to 0.5 wt.%, based on the total weight of the polymerizable monomers. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0104] An exemplary class of suitable radical initiators are organic peroxides, e.g. selected from: cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters and peroxyketals.

[0105] The radical initiator should be within the field of expertise. The radical initiator can be, for example, hydrogen peroxide. Alternatively, the radical initiator can also be an organic hydroperoxide. For the sake of completeness, it should be noted that the definition of hydroperoxides also includes materials such as organic peroxides or organic polyesters that decompose or hydrolyze to form organic hydroperoxides in situ: Examples of such peroxides and polyesters are cyclohexyl and hydroxycyclohexyl peroxide, and t-butyl perbenzoate, respectively.

[0106] In one embodiment of the disclosure, the radical initiator comprises at least one hydroperoxide compound represented by the following formula: R p OOH where: R p represents an aliphatic or aromatic group containing up to 18 carbon atoms, and typically where: R p for C1-C 12 -Alkyl, C6-C 18 -aryl or C7-C18 -aralkyl.

[0107] The one or more free radical initiators may include: cumene hydroperoxide (CHP); para-menthane hydroperoxide; t-butyl hydroperoxide (TBH); t-butyl perbenzoate; t-butyl peroxypivalate; di-t-butyl peroxide; t-butyl peroxyacetate; t-butyl peroxy-2-hexanoate; t-amyl hydroperoxide; 1,2,3,4-tetramethylbutyl hydroperoxide; benzoyl peroxide; dibenzoyl peroxide; 1,3-bis(t-butylperoxyisopropyl)benzene, diacetyl peroxide; butyl 4,4-bis(t-butylperoxy)valerate; p-chlorobenzoyl peroxide; t-butylcumyl peroxide; di-t-butyl peroxide; dicumyl peroxide; 2,5-dimethyl-2,5-di-t-butylperoxyhexane; 2,5-Dimethyl-2,5-di-t-butylperoxyhex-3-yn; and 4-methyl-2,2-di-t-butylperoxypentane.

[0108] Azo polymerization initiators may also be used and can be selected from: azo nitriles, azo esters, azo amides, azo amidines, azo imidazoline, macro azo initiators and combinations thereof.

[0109] Examples of suitable azo polymerization initiators include: 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobis(isobutyronitrile); 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); 1, 1'-azobis(cyclohexane-1-carbonitrile)-, 4,4'-azobis(4-cyanovaleric acid); dimethyl 2,2'-azobis(2-methylpropionate); 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]; 2,2'-azobis(N-butyl-2-methylpropionamide); 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride; 2,2'-Azobis[2-(2-imidazolin-2-yl)propane]; 2,2'-Azobis(2-methylpropionamidine) dihydrochloride, 2,2'-Azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate; 4,4-Azobis(4-cyanovaleric acid) polymer with alpha,omega-bis(3-aminopropyl)polydimethylsiloxane (VPS-1001, available from Wako Pure Chemical Industries, Ltd.); and 4,4'-Azobis(4-cyanopentanoic acid) polyethylene glycol polymer (VPE-0201, available from Wako Pure Chemical Industries, Ltd.).

[0110] Redox initiators can also be used and comprise a combination of an oxidizing agent and a reducing agent. Suitable oxidizing agents can be selected from cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters, peroxyketals, and mixtures thereof. The corresponding reducing agent can be selected from: alkali metal sulfites, alkali metal hydrogen sulfites, alkali metal metabisulfites, formaldehyde sulfoxylates, alkali metal salts of aliphatic sulfinic acids, alkali metal hydrogen sulfides; salts of polyvalent metals, in particular Co(II) salts and Fe(II) salts such as iron(II) sulfate, iron(II) ammonium sulfate, or iron(II) phosphate; dihydroxymaleic acid; benzoin; ascorbic acid; reducing saccharides such as sorbose, glucose, fructose, and / or dihydroxyacetone; and mixtures thereof.

[0111] Free-radical polymerization can be carried out in the presence of chain-transfer agents that transfer the free radicals and reduce the molecular weight of the resulting polymer and / or control chain growth during polymerization. When added, the chain-transfer agent can comprise between 0.01 and 1 wt.% of the mixture, based on the total weight of the polymerizable monomers. The amount of polymerization initiator and chain-transfer agents present contributes to the number-average molecular weight of the (co)polymer, although the choice of solvent may also play a role. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0112] The radical polymerization reactions are typically carried out in an organic solvent, typically a polar solvent. Effective polar solvents can have a boiling point of at least 20 °C, e.g., at least 30 °C, or at least 40 °C, measured at a pressure of 1 atmosphere (1.01325 bar).Examples of such polar solvents 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-di(C1-C4) alkyl acylamides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); hexamethylphosphoramide; N-methylpyrrolidone; pyridine; esters such as (C1-C8) alkyl acetates, ethoxydiglycol 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 an exemplary embodiment, the polymerization reaction is carried out in the presence of a (C1-C8)alkyl acetate, such as ethyl acetate.

[0113] The hydroxyl-functional (meth)acrylate copolymer (a1) can be prepared from the monomer mixture by a skew-feed polymerization process with at least two monomer feed streams. In one embodiment, the first feed stream comprises: I) 60 to 100 wt. % of the hydroxyl-functional adduct of the monoepoxy ester and the unsaturated carboxylic acid i), based on the total amount of component i) in the monomer mixture; II) 0 to 60 wt. % of the hydroxyl-functional unsaturated monomer ii), based on the total amount of monomer ii) in the monomer mixture; III) 0 to 30 wt. % of the unsaturated acid-functional monomer iii), based on the total amount of monomer iii) in the monomer mixture; and IV) 0 to 80 wt. % of the at least one (meth)acrylate monomer of the formula MA, based on the total amount of monomers iv) in the monomer mixture; V) 0 to 100 wt.-% of the at least one vinylaromatic monomer, based on the total amount of monomers v) in the monomer mixture; and VI) 0 to 100 wt.% of the other polymerizable unsaturated monomers vi), based on the total amount of monomers vi) in the monomer mixture. The remaining feed stream(s) comprise the remainder of the monomer components i) to vi). In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0114] In such a skew-feed polymerization, the entire amount of radical initiator to be fed can be added in full at the beginning of the first feed step. However, it is typical for fractions of the radical initiator to be added over time, and in particular, for one fraction to be added to each feed stream. Each initiator fraction fed to a particular feed stream of the reflux reactor can be added either as a single dose, stepwise, or continuously.

[0115] Analogously, the entire amount of organic solvent can be added at the beginning of the first feed step. However, it is typical for fractions of the organic solvent to be added over time, and in particular, for a fraction to be added to each feed stream. Typically, a solvent fraction specific to a particular feed stream can be added to the reflux reactor before or simultaneously with the start of monomer addition.

[0116] In certain embodiments of skew-feed polymerization, the reactor contents may be purged with an organic solvent after the addition of the first feed stream. An intermediate purge step may be performed similarly between each subsequent feed step.

[0117] The progress of the polymerization reaction and, optionally, each of its feed steps can be monitored by potentiometric titration to determine the hydroxyl number and / or the acid number. When these numbers reach a certain value based on a desired conversion level, the reactor contents are typically cooled and then partially or completely neutralized by adding the appropriate amount of base. The reactor contents, comprising the hydroxyl-functional (meth)acrylate copolymer (a1), can then be converted into an aqueous dispersion by normal dilution or reverse dilution with water. Component (a2)

[0118] The binder part a) of the two-part (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 about 500 to about 5000 Daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 100 to about 600 mg KOH / g; and a calculated hydroxyl functionality of about 2 to about 8. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those recited above, are expressly intended for use herein.

[0119] In important embodiments, the non-aromatic polyester (a2) has: a number average molecular weight (Mn) of about 500 to about 1500 Daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of about 4 to about 8. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0120] It is typical that the weight ratio of the solids of component (a1), the hydroxyl-functional (meth)acrylate copolymer(s), to the solids of component (a2), the polyester(s), is from about 100:1 to about 100:35, such as from about 100:5 to about 100:25, from about 100:5 to about 100:20, or from about 100:5 to about 100:15. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0121] Non-aromatic polyesters are typically produced by polycondensation of: at least one hydroxyl-functional component (a2h); at least one carboxyl-functional component (a2c); and optionally at least one hydroxycarboxylic acid component (a2hc). These components can be selected in type and amount to result in the non-aromatic polyester with the above-mentioned values for molecular weight, acid number, hydroxyl number, and functionality. In general, the polycondensation reaction can be illustrated by a stoichiometric excess of hydroxyl groups to carboxyl groups. Typically, the stoichiometric excess of hydroxyl groups to carboxyl groups can be between 5 and 40 mol%, for example between 5 and 35 mol%, between 5 and 30 mol%, or between 5 and 25 mol%.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0122] The hydroxyl-functional component (a2h) may comprise, based on the weight of the hydroxyl-functional component, from 75 to 100 wt.%, for example from 80 to 100 wt.% or from 90 to 100 wt.%, of at least one polyol having 3 to 6 hydroxyl groups; and from 0 to 25 wt.%, for example from 0 to 20 wt.% or from 0 to 10 wt.%, of at least one diol. In certain embodiments, the hydroxyl-functional component (a2h) may comprise, based on the weight of the hydroxyl-functional component, from 95 to 100 wt.% of at least one polyol having 3 to 6 hydroxyl groups; and from 0 to 5 wt.% of at least one diol. In other embodiments, the hydroxyl-functional component (a2h) consists essentially of or consists of the at least one polyol having 3 to 6 hydroxyl groups.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0123] Suitable polyols having 3 to 6 hydroxyl groups can be saturated or unsaturated and can be aliphatic or cycloaliphatic compounds. The compounds can typically have a molecular weight of 400 Daltons or less. Non-limiting examples of aliphatic triols include: 1,2,3-propanetriol; 1,2,4-butanetriol; 2-ethyl-2-hydroxymethyl-1,3-propanediol (trimethylolpropane), 3-methyl-1,3,5-pentanetriol; 1,2,3-hexanetriol; 1,2,6-hexanetriol; 2,5-dimethyl-1,2,6-hexanetriol; 1,2,3-heptanetriol; 1,2,3-octanetriol; and 2-hydroxymethyl-1,3-propanediol. Non-limiting examples of aliphatic tetrols and aliphatic pentols include: 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol); pentose; pentopyranose; 6-deoxyhexopyranose; 2,5-anhydrohexitol; 1,5-anhydrohexitol; 6-deoxyhexose; 1-deoxyhexitol; and pentitol. An exemplary polyol with 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 mixtures thereof may also be used.

[0124] The present disclosure does not exclude the use of (C2-C4) alkylene oxide adducts of the aforementioned diols, triols and higher polyols as polyol reactants having 3 to 6 hydroxyl groups.

[0125] Suitable diols for use in the hydroxyl-functional component can be saturated or unsaturated and aliphatic or cycloaliphatic dihydroxy compounds. The diol reactants typically have a molecular weight of 250 Daltons or less. When used herein, the term "diol" may include equivalent ester-forming derivatives thereof, provided, however, that the molecular weight requirement refers only to the diol and not to its derivative. Exemplary ester-forming derivatives are the acetates of the diols, as well as, for example, ethylene oxide or ethylene carbonate for ethylene glycol.

[0126] Typical diols are those with 2 to 10 carbon atoms. Examples of these diols include: ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methylpropanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol, hexanediol, decanediol, hexamethylene glycol; cyclohexanedimethanol; and polyoxyalkylene glycols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and tetrapropylene glycol. Mixtures of such diols can also be used.

[0127] The carboxyl-functional component (a2c) may comprise, based on the weight of the carboxyl-functional component, from 75 to 100 wt.%, such as from 80 to 100 wt.% or from 90 to 100 wt.%, of at least one dicarboxylic acid; and from 0 to 25 wt.%, such as from 0 to 20 wt.% or from 0 to 10 wt.%, of at least one monocarboxylic acid. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0128] Dicarboxylic acids suitable for use herein include aliphatic and / or cycloaliphatic dicarboxylic acids. The dicarboxylic acids may typically have a molecular weight of less than 600 Daltons. As used herein, the term "dicarboxylic acids" encompasses equivalents of dicarboxylic acids having two carboxylic functional groups that behave substantially like dicarboxylic acids when reacted with polyols to form polyesters. These equivalents include esters and ester-forming reactive derivatives such as acid halides and anhydrides, provided, however, that the above-mentioned molecular weight range refers to the acid and not to its equivalent ester or ester-forming derivatives. For example, an ester of a dicarboxylic acid with a molecular weight of more than 300 Daltons or an acid equivalent of a dicarboxylic acid with a molecular weight of more than 300 Daltons is included, provided that the acid has a molecular weight of less than 300 Daltons.Furthermore, the dicarboxylic acids may contain any substituent groups or combinations that do not substantially impair polymer formation and use of the polymer of this disclosure.

[0129] Typical dicarboxylic acids include those selected from: hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, and alkyldicarboxylic acids with a total of 2 to 16 carbon atoms. Representative alkyldicarboxylic acids include: glutaric acid, adipic acid, pimelic acid, succinic acid, sebacic acid, azelaic acid, and malonic acid. Adipic acid, for example, can be used.

[0130] Dimer fatty acids can be used as dicarboxylic acid reactants for the polyester synthesis reaction described above. Examples of dimer fatty acids include aliphatic C 36 - to C 44 -diacids obtained by oxidative coupling of unsaturated C 18 - to C 22Monoacids can be prepared. Dimer acids obtained from the oxidative coupling of oleic acid, linoleic acid, or tall oil fatty acid can be used. However, in embodiments where at least one dimer fatty acid is used in the reaction, it is typical for at least one non-dimerized dicarboxylic acid to be present. In particular, when at least one dimer fatty acid is employed, the dimer fatty acid can be reacted in an amount of from 5 to 50 wt.%, typically from 5 to 40 wt.%, from 5 to 30 wt.%, or from 5 to 25 wt.%, based on the total weight of the carboxyl-functional component. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0131] Monocarboxylic acids suitable as reactants for the polycondensation reaction include aliphatic and / or cycloaliphatic monocarboxylic acids. The monocarboxylic acids can typically have a molecular weight of less than 300 Daltons. Exemplary monocarboxylic acids that can be used alone or in combination include: formic acid, acetic acid, propionic acid, n-butanoic acid, isobutanoic acid, 2-ethylhexanoic acid, octanoic acid, isononanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, palmitic acid, and stearic acid.

[0132] A (cyclo)aliphatic hydroxycarboxylic acid component (a2hc) may optionally participate in the polycondensation reaction, yielding the non-aromatic polyester polyol (a2). When present, the total amount of hydroxycarboxylic acid typically amounts to a maximum of 10 wt.%, based on the total weight of the reactant compounds (a2h, a2c, and a2hc). Examples of hydroxycarboxylic acids include: 12-hydroxystearic acid, 6-hydroxyhexanoic acid, citric acid, tartaric acid, and dimethylolpropionic acid. Instead of the monohydroxycarboxylic acids, the corresponding lactones can also be used as reactants.

[0133] It is typical herein that the reaction mixture for the above-mentioned polycondensation reaction is essentially free of solvents. Furthermore, the starting reaction mixture may be essentially free of added water. However, if the reaction is carried out in solution, suitable solvents may be non-reactive, essentially anhydrous, organic liquids capable of dissolving at least 1% and typically more than 10% by weight of the polyester products at 25°C. Suitable organic solvents, which may be used alone or in combination, include: aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as heptane and decane, alicyclic hydrocarbons such as cyclohexane and decalin, chlorinated hydrocarbons such as chloroform and trichloroethylene, esters such as ethyl acetate and methyl butyrate, and ethers such as tetrahydrofuran (THF) and dioxane.

[0134] The polycondensation reaction can be carried out in the presence of a suitable catalyst. Common catalysts include acid catalysts and organometallic catalysts, with titanium, zirconium, and tin alkoxides, carboxylates, and chelates being examples of the latter. Typically, the catalyst is a titanium alkoxide, titanium carboxylate, or titanium chelate catalyst.

[0135] Examples of titanium alkoxides include: tetramethyl titanates; tetraethyl titanates; tetrapropyl titanates; tetraisopropyl titanates; tetrabutyl titanates; tetrapentyl titanates; tetrahexyl titanates; tetraoctyl titanates; tetranonyl titanates; tetradodecyl titanates; tetrahexadecyl titanates; tetraoctadecyl titanates; tetradecyl titanates; tetraheptyl titanates; and mixtures thereof. The tin or zirconium counterparts of the above-mentioned alkoxides can be used as catalysts.

[0136] It is typical for the catalyst to be used in an amount of 0.1 to 5 wt.%, for example, from 0.1 to 2.0 wt.%, from 0.1 to 1.5 wt.%, or from 0.1 to 1.0 wt.%, based on the total weight of the reactants (a2h, a2c, and a2hc). In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0137] The polycondensation reaction can also be carried out in the presence of at least one stabilizer. Typical stabilizers—usually present in an amount of 0.01 to 5 wt.%, based on the total weight of the reactants (a2h, a2c, and a2hc)—can be: hydroquinone and its alkylated derivatives; phenolic compounds with electron-withdrawing substituents; and quinoid 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-tertiarybutylcatechol; 4-methoxyphenol; methylhydroquinone; 4-chloro-2-nitrophenol; 2,4-dinitroparacresol; 2,4-dinitrophenol; and phenothiazine.

[0138] If a stabilizer is used in the polycondensation reaction, one or more known electron donors can also be added to the mixture of reactants to form electron donor-acceptor complexes. Typical electron donors—which would typically total 0.01 to 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-methylimidazyl)-1-cyanoethane; and 2-undecylimidazole. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0139] In the synthesis of polyesters, the reactants, catalyst(s), and any stabilizers and electron donors used are typically placed in a suitable reaction vessel with a distillation device. This vessel is typically dried and purged with an inert gas—such as nitrogen or argon—before being filled, and this inert gas atmosphere can be maintained in the vessel throughout the reaction. The temperature of the vessel is typically set based on the lowest boiling point of the reactants, usually an alcohol. In various embodiments, a temperature of about 125 to about 300°C or about 125 to about 275°C can be considered standard.For an initial period, the vessel can be kept at atmospheric pressure, but once water distillation is no longer observed, at least a partial vacuum can be applied to the vessel to complete the polycondensation reaction.

[0140] The reaction can be monitored by analyzing the acid number (Av) of the reactant mixture over time, and the reaction is typically stopped when the determined acid number reaches a value of less than about 10 mg KOH / g, or ideally less than about 5 mg KOH / g, or even less than about 1 mg KOH / g. The time to reach this point depends on various factors, such as temperature, catalyst type, and the reactants used: generally, however, it is between about 0.5 and about 20 hours, for example, between about 1 and about 8 hours, or between about 2 and about 6 hours. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0141] The polyester synthesized by the polycondensation reaction can be separated and purified using known methods such as filtration, extraction, evaporation, distillation or chromatography. (a3) Additional (meth)acrylate copolymer

[0142] The binder part a) of the composition may, in certain embodiments, further comprise: (a3) at least one (meth)acrylate copolymer having active hydrogen groups which is different from the hydroxyl-functional (meth)acrylate polymer(s) of component (a1), wherein the (meth)acrylate copolymer (a3) has a water solubility at about 20°C of less than about 6 g / 100 ml of water.

[0143] This additional or co-binder (meth)acrylate component (a3) would typically be a minority component of the binder part a). For example, in certain embodiments, the (meth)acrylate copolymer (a3) may be present in the binder part a) in an amount of from 0 to 20 wt.%, based on the weight of the binder part a). In certain embodiments, the (meth)acrylate copolymer (a3) may be present in part a) in a proportional amount relative to its component (a1), such as in an amount of from 0 to 20 wt.%, from 0 to 10 wt.%, or from 1 to 5 wt.%, based on the weight of component (a1). In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0144] The (meth)acrylate copolymer of component (a3) is not only water-insoluble but also potentially insoluble in water. For example, the copolymer typically does not form a stable dispersion in water, so the dispersion would exhibit settling or phase separation upon storage at 40 °C for 4 weeks. The inclusion of such a copolymer tends to increase the hydrophobicity of the waterborne coating composition, which can improve its applicability as well as the etch and weathering resistance of the resulting coatings.

[0145] In certain embodiments, the (meth)acrylate polymer of component (a3) has: a calculated hydroxyl number of about 100 to about 600 mg KOH / g; an acid number of about 0 to about 35 mg KOH / g; and a number average molecular weight of about 1000 to about 4000 Daltons. In other embodiments, the (meth)acrylate polymer of component (a3) has: a calculated hydroxyl number of about 100 to about 300 mg KOH / g, such as about 100 to 200 mg KOH / g; an acid number of about 0 to about 30 mg KOH / g, such as about 10 to 30 mg KOH / g; and a number average molecular weight of about 1000 to about 4000 Daltons. Within the binder part a), the co-binder component (a3) may be further characterized by having a particle size of about 60 to about 200 nm, as determined by laser diffraction.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0146] The hydroxy-functional (meth)acrylic copolymer(s) (a3) may be commercially available or prepared as described above. The ethylenically unsaturated monomers in this copolymerization may be selected in type and amount to obtain the desired molecular weight, acid number, and hydroxyl number for the copolymer. The synthesis of (meth)acrylic copolymer B from the examples of US2012237688A1 (Huybrechts et al.) may be used herein, which reference is expressly incorporated by reference in its entirety in various non-limiting embodiments. (a4), (a5) Non-polymeric polyol

[0147] The addition of certain low-molecular-weight non-polymeric polyols to part a) of the composition can improve the moisture resistance of the coatings obtained from the compositions and promote easier mixing between the two parts of the composition. Any improvement in such mixing can result in better applicability of the coating compositions and an improved appearance of the resulting coatings.

[0148] In one embodiment, the binder part a) of the two-part (2K) composition may further comprise: (a4) at least one non-polymeric, acyclic polyol having a weight-average molecular weight (Mw) of less than about 300 Daltons and a water solubility at about 20°C of less than about 6 g / 100 ml of water. For example, the (a4) at least one non-polymeric, acyclic polyol may be present in the binder part a) in an amount of 0 to 10 wt. %, based on the weight of the binder part a). In certain embodiments, the (a4) at least one non-polymeric, acyclic polyol may be present in the binder part a) in a fraction of the amount of component (a1). For example, the binder part a) may contain 0 to 10 wt.%, 0 to 8 wt.%, 0 to 5 wt.% or 0 to 3 wt.% of the at least one non-polymeric acyclic polyol (a4), based on the weight of component (a1).In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0149] Exemplary non-polymeric, acyclic polyols that can be used alone or in combination include: 2-ethylhexane-1,3-diol; and 2-butyl-2-ethyl-1,3-propanediol.

[0150] In another embodiment, which is not mutually exclusive, the binder part a) of the two-part (2K) composition may further comprise: (a5) at least one non-polymeric, cycloaliphatic polyol having a weight-average molecular weight (Mw) of less than about 300 Daltons. For example, the (a5) at least one non-polymeric, cycloaliphatic polyol may be present in the binder part a) in an amount of 0 to 10 wt. %, based on the weight of the binder part a). In certain embodiments, the (a5) at least one non-polymeric, cycloaliphatic polyol may be present in the binder part a) in a fraction of the amount of component (a1). For example, the binder part a) may comprise 0 to 10 wt.%, 0 to 8 wt.%, 0 to 5 wt.% or 0 to 3 wt.% (a5) of at least one non-polymeric, cycloaliphatic polyol, based on the weight of component (a1).In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0151] 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-cyclohexanediethanol; 2,2-bis(4-hydroxycyclohexyl)propane; dianhydro-D-glucitol (isosorbide); and 4,8-bis(hydroxymethyl)tricyclo[5.2.1.0 2,6 ]decane. In one embodiment, the at least one non-polymeric, cycloaliphatic polyol comprises 1,4-cyclohexanedimethanol. Part b) Crosslinkers

[0152] The crosslinker part b) of the present composition comprises at least one polyisocyanate compound with pendant -NCO groups. It is not excluded that the crosslinker part b) of the composition may comprise, in addition to the polyisocyanate compound(s) with pendant -NCO groups, other crosslinking compounds, such as melamine resins and blocked isocyanates.

[0153] The molar ratio of active hydrogen atoms to -NCO groups in the two-part (2K) composition is between about 5:1 and about 1:5, typically between about 3:1 and about 1:3. The molar ratio of active hydrogen atoms to -NCO groups can be, for example, from about 2:1 to about 1:2 or from about 1.5:1 to about 1:1.5. The term "-NCO groups" includes blocked -NCO groups, which are therefore included in the term molar ratio. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0154] The term "polyisocyanate" refers to a compound with at least two functional -N=C=O groups, for example, 2 to 5 or 2 to 4 functional -N=C=O groups. Suitable polyisocyanates include aliphatic, cycloaliphatic, aromatic, and heterocyclic isocyanates, their dimers and trimers, and mixtures thereof.

[0155] Aliphatic and cycloaliphatic polyisocyanates can contain 6 to 100 carbon atoms, which are linked in straight-chain or cyclic fashion and have at least two reactive isocyanate groups. Examples of suitable aliphatic isocyanates are straight-chain isocyanates such as ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 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-trimethylcyclohexane (isophorone diisocyanate, IPDI), cyclohexane-1,4-diisocyanate, hydrogenated xylylene diisocyanate (H6XDI), 1-methyl-2,4-diisocyanatocyclohexane, m- or p-tetramethylxylene diisocyanate (m-TMXDI, p-TMXDI), and dimer fatty acid diisocyanate. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0156] The term "aromatic polyisocyanate" is used herein to describe organic isocyanates in which the isocyanate groups are directly bonded to the ring(s) of a mono- or polynuclear aromatic hydrocarbon group. A mono- or polynuclear aromatic hydrocarbon group, in turn, is understood to be an essentially planar cyclic hydrocarbon unit with conjugated double bonds, which may consist of a single ring or comprise multiple fused or covalently bonded rings. The term aromatic includes alkylaryl. Typically, the hydrocarbon (main) chain contains 5, 6, 7, or 8 main chain atoms in a cycle. Examples of such planar cyclic hydrocarbon residues are cyclopentadienyl, phenyl, naphthalenyl,

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

[12] annulenyl-, [8]annulenyl-, phenalin (perinaphthene), 1,9-dihydropyrene, chrysene (1,2-benzophenanthrene).Examples of alkylaryl units are benzyl, phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-naphthylpropyl, 2-naphthylpropyl, 3-naphthylpropyl and 3-naphthylbutyl.

[0157] Exemplary aromatic polyisocyanates include: all isomers of toluene diisocyanate (TDI), either in isomerically pure form or as a mixture of several isomers; naphthalene 1,5-diisocyanate; diphenylmethane 4,4'-diisocyanate (MDI); diphenylmethane 2,4'-diisocyanate and mixtures of diphenylmethane 4,4'-diisocyanate with the 2,4'-isomer or mixtures thereof with oligomers of higher functionality (so-called crude MDI); xylylene diisocyanate (XDI); diphenyldimethylmethane 4,4'-diisocyanate; di- and tetraalkyl diphenylmethane diisocyanates; dibenzyl 4,4'-diisocyanate; phenylene 1,3-diisocyanate; phenylene 1,4-diisocyanate; triphenylmethane triisocyanate, 1,3,5-benzene triisocyanate and 2,4,6-toluene triisocyanate.

[0158] When used, the polyisocyanates may have been biuretized, allophanated, and / or isocyanurated by well-known methods. Upon use, such derivatives may be substantially free of parent diisocyanate. The derivatives may have been separated from excess parent diisocyanate by conventional means, including, but not limited to, distillation.

[0159] It is also 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 obtain isocyanate-functional oligomers, which can be used alone or in combination with free isocyanates.

[0160] The term "polyisocyanate" further encompasses ionically modified, isocyanate-functional compounds, e.g., ionically modified, isocyanate-functional prepolymers. The ionically modified polyisocyanates contain at least two isocyanate groups and at least one ionic or ionogenic group. In certain embodiments, anionically modified, isocyanate-functional compounds, such as anionically modified, isocyanate-functional prepolymers, can be incorporated into the crosslinker part b). Suitable anionic or ionogenic groups in this context are carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, and salts thereof. Suitable bases that can neutralize the anionic groups to form such salts include alkali metals such as Na and K, ammonium, and trialkylamines such as triethylamine and triisopropylamine.

[0161] Exemplary polyisocyanates commercially available from Covestro AG that may be used in the present disclosure include: Desmodur® N3900; Bayhydur® Ultra 2487 / 1; Bayhydur *Ultra 2700; Bayhydur® Ultra 3100; Bayhydur ®Ultra 304; Bayhydur *Ultra 305; Bayhydur *Ultra 307; Bayhydur ®XP 2451 / 1; Bayhydur ®XP 2547; Bayhydur ® XP 2655; Bayhydur ® XP 2759; Bayhydur ® 2858 XP; Bayhydur ® Eco 701-90; Bayhydur ® 401-60 PGDA and Bayhydur ® 401-70 MPA / X. Additives and supplementary ingredients

[0162] The compositions of the present disclosure may further contain or be free of one or more adjuvants and additives that can impart improved 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 dullness; improved image definition (DOI); longer permitted working time; faster cure time; lower residual tack; and improved leveling. Such adjuvants and additives include: catalysts, plasticizers, stabilizers including UV stabilizers, reactive diluents, desiccants or moisture scavengers, adhesion promoters, wetting agents, defoamers, flame retardants, rheology control agents, color pigments, dyes, effect pigments, co-solvents, and non-reactive diluents.

[0163] Such auxiliaries and additives may be used in any combination and in any proportion, provided they do not impair the nature and essential properties of the composition. Although there may be exceptions in some cases, these auxiliaries and additives typically constitute between 0 and 40% by weight, for example, between 0 and 30% by weight of the total composition.

[0164] In general, additives and excipients containing reactive groups can be blended into the corresponding part of a two-part (2K) composition to ensure its storage stability; non-reactive substances can be formulated into one or both parts. For example, in certain embodiments, the crosslinker part b) of the composition can be free of compounds containing active hydrogen atoms.

[0165] The compositions may comprise one or more catalysts for the reaction of -NCO groups with active hydrogen compounds. Standard catalysts known in the art include: tin(II) salts of carboxylic acids, such as tin(II) octoate, tin(II) oleate, tin(II) acetate, and tin(II) laureate; 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 alcoholates; tin alkoxides, such as dibutyltin dimethoxide, dibutyltin diphenoxide, and dibutyltin diisoproxide; tin oxides, such as dibutyltin oxide and dioctyltin oxide; the reaction products of dibutyltin oxides and phthalic acid esters; tin mercaptides; alkyl titanates; organoaluminium compounds such as aluminium trisacetylacetonate, aluminium trisethylacetoacetate and diisopropoxyaluminium ethylacetoacetate;Chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylacetonate; organosilicon titanium compounds; bismuth tris-2-ethylhexanoate; acidic compounds such as phosphoric acid and p-toluenesulfonic acid; triphenylborane; triphenylphosphine; 1,8-diazabicycloundec-7-ene (DBU); 1,5-diazabicyclo[4.3.0]non-5-ene; 1,4-diazabicyclo[2.2.2]octane; 4-dimethylaminopyridine; 1,5,7-triazabicyclo[4.4.0]dec-5-ene; 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene; 1,8-bis(tetramethylguanidino)naphthalene; and 2-tert-butyl-1,1,3,3-tetramethylguanidine.

[0166] Depending on the type of isocyanate, the amount of catalyst used typically ranges from 0.005 to 2 wt.% of the composition. For example, the composition may comprise 0.01 to 2 wt.% or 0.01 to 1 wt.% catalyst based on the weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0167] The addition of certain additives can promote the adhesion of the coating compositions to certain substrates. In this context, the composition may comprise 0 to 5% by weight, for example 0.5 to 5% by weight, based on the weight of the composition, of at least one additive selected from: morin (2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-coumarone-4-ketone), 3,7-dihydroxy-2-naphthoic acid (3,7-dihydroxy-naphthene-2-carboxylic acid), pyrogallolcarboxylic acid (2,3,4-trihydroxybenzoic acid); 3,4-dihydroxybenzeneguanidineacetic 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.

[0168] The term “pigment,” as used herein, refers to a molecule that is insoluble in the liquid carrier and imparts either a color or an optical effect to it.

[0169] In certain embodiments, the composition may comprise at least one color pigment. Color pigments useful here may be organic or inorganic.Example color pigments that can be used alone or in combination include: azo pigments; anthraquinone pigments; benzimidazolone pigments; isoindoline pigments; naphthol pigments such as naphthol red; nitroso pigments; perinone pigments; perylene pigments; polycyclic pigments; pyrropyrrole pigments; pthalocyanines such as copper pthalocyanine blue and copper pthalocyanine green; quinacridones such as quinacridone violet; quinophthalone pigments; dioxazine pigments; carbon black, anazurite; aluminum silicate; aluminum potassium silicate; antimony oxide; barium metaborate; barium sulfate; cadmium sulfide; cadmium selenide; calcium carbonate; calcium metaborate; calcium metasilicate; chromium oxides; clay; copper oxides; copper oxychloride; feldspar; iron oxides such as yellow and red iron oxides; kaolinite; lithopone; magnesium silicates; Nepheline syenite; silicates; sulfides; talc; titanium dioxide; ultramarine; zinc chromate; zinc oxide; and zinc phosphate.

[0170] In certain embodiments, the composition may contain at least one effect pigment, i.e., a pigment that exhibits optical effects not caused by absorption. Particular examples are graphite effect pigments, metallic effect pigments, and pearlescent pigments. The effect pigments may have at least one of the following features: a specific surface area of about 1 to about 60 m 2 / g, e.g. from about 5 to about 50 m 2 / g, as determined using nitrogen absorption according to the Brunauer-Emmett-Teller (BET) method; and a volume median particle size (Dv50) of about 1 to about 500 µm, e.g., from about 5 to about 100 µm, as determined by laser diffraction. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0171] The metallic effect pigments can contain needle-shaped, spherical, ellipsoidal, cylindrical, pearl-like, cubic, platelet-shaped, or flaky particles. Particles of different shapes can be used alone or in combination.

[0172] Example metals that may comprise metallic effect pigments include: aluminum, copper, copper-zinc alloys, copper-tin alloys, stainless steel, carbon steel, iron, silver, zinc, nickel, titanium, chromium, manganese, vanadium, magnesium, and zinc-magnesium alloys. The metal component may be coated with one or more inert oxides to form the effect pigment. Example metal oxides include: silicon dioxide, titanium dioxide, zinc oxide, zirconium dioxide, tin oxide, cerium dioxide, vanadium oxide, manganese oxide, lead oxide, chromium oxide, iron oxide, aluminum oxide, and tungsten oxide. When present in the pigment, the thickness of such metal oxide layers is typically 20 to 400 nm, e.g. B. 50 to 400 nm or 50 to 250 nm. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above are expressly intended for use herein.

[0173] Pearlescent pigments consist of a transparent, non-metallic, platelet-shaped substrate coated with at least one layer of metal oxides with different refractive indices. In some embodiments, multiple layers of metal oxides are used, with a difference of at least about 0.1 in the refractive indices of the successive layers. In some embodiments, the pearlescent pigment exhibits an interference color when viewed against a black background.

[0174] Example non-metallic platelet substrates include: natural mica, synthetic mica, bismuth oxychloride, graphite, alumina, iron mica, pearlite, silicon dioxide, borosilicate glass, glass, titanium dioxide coated mica, and iron oxide coated mica.

[0175] Exemplary metal oxides from which the one or more coating layers of the pearlescent pigments may be formed include: silicon dioxide, titanium dioxide, zinc oxide, zirconium dioxide, tin oxide, cerium dioxide, vanadium oxide, manganese oxide, lead oxide, chromium oxide, iron oxide, aluminum oxide, and tungsten oxide. The thickness of each metal oxide layer of the pearlescent pigment can be determined independently, but is typically between about 20 and about 400 nm, for example, between 50 and 400 nm or between 50 and 250 nm. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0176] The rheology control agent that may optionally be useful in the present composition may include fillers, thickeners, and combinations thereof. The total amount of rheology control agent in the composition will normally not exceed 10 wt.%, based on the weight of the composition. For example, the composition may comprise 0 to 8 wt.%, 0 to 5 wt.%, or 0 to 2 wt.% rheology control agent, based on the weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0177] Examples of thickeners include clay-based thickeners such as organoclays; polysaccharides such as guar and xanthan gum; polyacrylates; and associative thickeners. The following cellulose or cellulose derivatives can be used as polysaccharide thickeners: carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, cellulose nanofibers, and cellulose nanocrystals.

[0178] The filler may contain acicular, spherical, ellipsoidal, cylindrical, spherical, cubic, or platelet-shaped particles, which may be used individually or in combination. Furthermore, agglomerates of more than one particle type may also be used. The fillers typically have a volume median particle size (Dv50), measured by laser diffraction, of about 0.1 to about 1500 µm, for example, from about 1 to about 1250 µm. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0179] Examples of fillers include calcium carbonate, calcium oxide, calcium hydroxide (lime powder), precipitated and / or fumed silica, zeolites, bentonites, wollastonite, magnesium carbonate, diatomaceous earth, barium sulfate, aluminum oxide, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass beads, glass powder, and other ground mineral materials. Organic fillers may also be used, particularly wood fibers, wood flour, sawdust, cellulose, cotton, wood pulp, cotton, wood shavings, shredded straw, chaff, ground walnut shells, and other shredded fibers. Short fibers such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers, Kevlar fibers, or polyethylene fibers may also be added.

[0180] When present, fumed and / or precipitated silica can have a specific BET surface area of about 10 to about 90 m 2 / g. If such silica(s) are used, they may not result in an additional increase in the viscosity of the composition, but may contribute to the strengthening of the cured composition. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0181] It is also conceivable to use pyrogenic and / or precipitated silica with a higher specific BET surface area, advantageously from about 100 to about 250 m 2 / g, to be used as a filler: Due to the larger BET surface area, the effect of reinforcing the cured composition is achieved with a lower weight fraction of silica. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0182] Hollow spheres with a mineral or plastic shell can also be used. These can be, for example, hollow glass spheres commercially available under the trade name Glass Bubbles®. Plastic-based hollow spheres, such as Expancel1® or Dualite®, can also be used. They can contain, for example, inorganic or organic substances and each have a volume-related median particle size (Dv50) of 1 mm or less, typically 500 µm or less, as determined by laser diffraction.

[0183] 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 swellable plastics such as PVC.

[0184] A “plasticizer” within the meaning of this disclosure is a substance that reduces the viscosity of the composition and thus facilitates its processability. The plasticizer can make up to 10% by weight or up to 5% by weight, based on the total weight of the composition, and is typically selected from: diurethanes; ethers of monofunctional, linear or branched C4-C16 alcohols, such as Cetiol OE (available from BASF); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid esters and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-group-bearing 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 glycols; polystyrene; Hydrocarbon plasticizers; chlorinated paraffin; and mixtures thereof.It should be noted that, in principle, phthalic acid esters can be used as plasticizers, but they are not commonly used due to their toxicological potential.

[0185] For the purposes of this disclosure, "stabilizers" include antioxidants, thermal stabilizers, or hydrolysis stabilizers. The stabilizers may total up to 10 wt.% or up to 5 wt.%, based on the total weight of the composition. Commercially available examples of stabilizers that may be used include: hindered phenols, thioethers, benzotriazoles, benzophenones, benzoates, cyanoacrylates, acrylates, hindered amine light stabilizers (HALS), phosphorus, sulfur, and mixtures thereof.

[0186] To further extend shelf life, it is often advisable to further stabilize the compositions of the present disclosure against moisture penetration through the use of desiccants. Examples of suitable desiccants or moisture scavengers include: silica gel, anhydrous calcium sulfate (anhydrite), calcium sulfate dihydrate (gypsum), calcium oxide, montmorillonite clay, molecular sieves such as natural or synthetic zeolite, and activated alumina.

[0187] Waxes useful in the present disclosure may have a softening point of about 50 to about 150°C and may include one or more of the following: polyethylene having a number average molecular weight (Mn) of about 500 to about 7500; petroleum waxes, such as paraffin wax and microcrystalline wax; synthetic waxes produced by polymerizing carbon monoxide and hydrogen, such as Fischer-Tropsch wax; polyolefin waxes, including functionalized polyolefin waxes, of which maleated polyethylene, maleated polypropylene, and maleated poly(ethylene-co-propylene) may be cited as examples; and hydrogenated animal, fish, or vegetable oils. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those recited above, are expressly intended for use herein.

[0188] Occasionally, there is also a need to reduce the viscosity of the composition according to the present disclosure for certain applications through the use of reactive diluent(s). The total amount of reactive diluent present is typically between 0 and 10 wt.%, for example, between 0 and 5 wt.%, based on the total weight of the composition. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0189] The presence of co-solvents and non-reactive diluents in the compositions of the present disclosure is also not excluded if this can usefully moderate the viscosity of the compositions. For example, but only by way of illustration, the compositions may contain one or more of the following: alkyl acetate solvents such as ethyl acetate, n-propyl acetate, butyl acetate, n-butyl acetate, propylene glycol monomethyl ether acetate, and methoxypropyl acetate (MPA); alkyl propionate solvents such as n-butyl propionate and n-pentyl propionate; dibasic esters 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 mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butylyl ether, propylene glycol butyl ether, propylene glycol phenyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol di-n-butyl ether; amide solvents such as dimethylacetamide and N-methylpyrrolidone; ketone solvents such as acetone, diisobutyl ketone, isobutyl heptyl ketone, isophorone, methyl ethyl ketone, methyl n-amyl ketone, and methyl isobutyl ketone; toluene; xylene; Diphenylmethane; diisopropylnaphthalene; petroleum fractions such as Solvesso® products (available from Exxon); and chlorinated hydrocarbon solvents such as 4-chlorotrifluoromethylbenzene and 3,4-bis(dichloro)trifluoromethylbenzene.

[0190] Any cosolvents or non-reactive diluents of the two-part (2K) composition need not be added independently to one or more components or to the composition itself. Alternatively, one or more components of the composition may be contained in a cosolvent or diluent. Any solvent or diluent contained in the crosslinker part b) of the composition may, in certain embodiments, be free of active hydrogen atoms.

[0191] It is typical for co-solvents and non-reactive diluents to total less than 5 wt.%, especially less than 1 wt.%, based on the total weight of the composition. By at least partially excluding these co-solvents and non-reactive diluents, the water-based two-part (2K) composition can have a volatile organic compound (VOC) content of no more than about 420 g / L, e.g., no more than about 360 g / L, such as no more than about 300 g / L, or even no more than about 240 g / L. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein. Methods and applications

[0192] In two-part (2K) curable compositions, the reactive components are brought together and mixed to initiate curing. The reactive components can be mixed under sufficient shear to obtain a homogeneous mixture. This can be achieved without special conditions or specialized equipment. Suitable mixing devices may include static mixers, magnetic stirrers, wire stirrers, screws, batch mixers, planetary mixers, CW Brabender or Banburry® mixers, and high-shear mixers such as paddle mixers and rotary agitators. In certain embodiments, one or more of the following may be added after mixing the reactive components: water, co-solvent, or non-reactive diluent to reduce the viscosity of the composition.

[0193] For small applications, where volumes of less than 2 liters are used, the typical packaging for two-part (2K) compositions are juxtaposed double cartridges or coaxial cartridges, in which two tubular chambers are arranged side by side or inside each other and closed by pistons. The drive of these pistons allows the extrusion of the parts from the cartridge, advantageously through a tightly fitted static or dynamic mixer. For larger volume applications, the two parts of the composition can advantageously be stored in drums or buckets. In this case, the two parts are extruded via hydraulic presses, in particular follower plates, and fed via pipelines to a mixing device capable of ensuring a fine and very homogeneous mixing of the hardener and binder parts.The binder part is typically sealed airtight and moisture-tight so that both parts can be stored for a long time, ideally 12 months or more.

[0194] Non-limiting examples of two-part dosing devices and methods that may be suitable for the present disclosure include those described in U.S. Patent Nos. 6,129,244 and 8,313,006, each of which is expressly incorporated by reference in its entirety in various non-limiting embodiments.

[0195] Typically, the compositions described above are applied to the required surface(s) and then cured in situ. Before applying the compositions, it is often advisable to pretreat the surfaces in question to remove foreign matter. This step may facilitate subsequent adhesion of the compositions to the surfaces. Such treatments are known in the art and can be carried out in one or more steps.

[0196] In some embodiments, the adhesion of the coating compositions to the optionally pretreated substrate surface can be facilitated by applying a primer layer. Primer compositions may be necessary to ensure effective fixation and / or curing times of the adhesive compositions on inactive substrates.

[0197] The provision of further intermediate layers between the primer and the coating compositions of the present disclosure is not precluded, as described below with respect to multi-layer coatings.

[0198] Typically, the compositions are applied to the required surfaces of the substrate by conventional application methods such as: brushing, roller coating, knife coating, printing methods and spraying methods, including but not limited to air atomized spraying, air assisted spraying, airless spraying and HVLP low pressure spraying.

[0199] The compositions are applied to a surface with a wet film thickness of about 10 to about 500 µm. Applying thinner layers in this range is more economical and reduces the likelihood of damaging thick cured areas. However, when applying thinner coatings or layers, care must be taken to avoid the formation of discontinuous cured films. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0200] The applied compositions are typically cured at temperatures from about 20 to about 200°C, typically from about 20 to about 160°C. The appropriate temperature depends on the specific compounds present and the desired curing rate and can be determined in each individual case by a person skilled in the art, possibly through simple preliminary testing. For example, for applications in vehicle production, a curing temperature of from about 80 to about 160°C or from about 100 to about 140°C may be effective. Conversely, for refinishing applications, a curing temperature of from about 20 to about 80°C or from about 40 to about 60°C may be effective. For applications on large vehicles and transport vehicles - such as trucks, buses, and railroad cars - a curing temperature of from about 20 to about 80°C may be used.Of course, curing at lower temperatures within the aforementioned ranges is advantageous, as it eliminates the need to significantly heat or cool the mixture above the normally prevailing ambient temperature. However, if desired, the temperature of the mixture formed from the respective components of the composition may be raised above the mixing temperature and / or the application temperature by conventional means, including firing and microwave induction. In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0201] The present disclosure also provides an article comprising: a metal substrate; and a multilayer coating disposed on the metal substrate, wherein at least one layer of the multilayer coating comprises the cured compositions described herein. While the use of the cured compositions as a primer—such as a primer or sealer—within a multilayer coating is not precluded, the cured coating compositions are more suitable for use in or as: a solid-color basecoat; a solid-color topcoat; and / or a clearcoat. For example, the cured coating composition can be used in or as transparent clearcoat(s).

[0202] An example item is shown in the attached Fig.1. The illustrated article (1) comprises: a metal substrate (10); and a multi-layer coating (11) disposed on the metal substrate, wherein the multi-layer coating (11) comprises: a primer layer (110) disposed on the metal substrate; a basecoat layer (120) comprising a color and / or visual effect-imparting compound, wherein the basecoat layer is disposed on the primer layer (110); and a clearcoat layer (130) comprising the cured product of the above-described two-part (2K) composition and disposed on the basecoat layer (120).

[0203] The primer layer (110) is typically applied to promote adhesion between the substrate surface and subsequent coating layers. Furthermore, primer layers can serve to improve the physical properties of the overall coating system, particularly corrosion resistance and impact resistance. Furthermore, the primer layer can contribute to the overall appearance of the coating system by forming a smooth layer onto which subsequent layers can be applied.

[0204] The primer layer (110) is in Fig.1 is shown arranged on the metal substrate (10) and in direct contact therewith. However, it is understood that one or more intermediate layers may be arranged between the metal substrate and the primer layer (110). A conversion layer is a representative example of such an intermediate layer. The term "conversion" refers here to a treatment of the surface of a substrate by which the surface material is chemically converted into another material. Typically, a metallic or alloyed surface substrate is chemically treated to produce a firmly adherent conversion layer consisting wholly or partially of a stabilized form—for example, 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).

[0205] In Fig. 1, a single primer layer (110) is shown for illustrative purposes only. However, in certain embodiments, more than one primer layer (110) may be present. Regardless of whether the primer is applied in a single or multiple layers, the total thickness of the at least one primer layer may typically be between about 10 and about 200 micrometers, for example, between about 10 and about 150 micrometers, between about 10 and about 75 micrometers, or between about 20 and about 75 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly intended for use herein.

[0206] The Fig.The basecoat layer (120) shown in Figure 1 comprises a color and / or visual effect-imparting compound and is disposed on the primer layer (110). If the primer has been applied in multiple layers, the basecoat layer is disposed on the uppermost primer layer with respect to the surface of the metal substrate (10).

[0207] In Fig.1, a single basecoat layer (120) is shown for illustrative purposes only. However, in certain embodiments, more than one basecoat layer (120) may be present. The lowermost of these basecoat layers may be disposed on top of, and in direct contact with, a primer layer (110). Regardless of whether the primer is applied in a single or multiple layers, the total thickness of the at least one basecoat layer may typically be about 5 to about 100 micrometers, for example, about 5 to about 50 micrometers, about 5 to about 40 micrometers, or about 5 to about 30 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those recited above, are expressly intended for use herein.

[0208] In Fig.1, a clear coat layer (130) containing the cured product of the above-described two-part (2K) composition is applied on the base coat layer (120). If the base coat has been applied in multiple layers, the clear coat layer (130) is applied on the uppermost base coat layer relative to the surface of the metal substrate (10). The clear coat layer (130) typically exhibits good chemical resistance as well as good resistance to mechanical wear and weathering. Furthermore, the clear coat layer (130) has satisfactory optical properties, including transparency and gloss.

[0209] Here too, Fig.1 only a single clear coat layer (130) is shown for illustrative purposes. However, in certain embodiments, more than one clear coat layer (130) may be present. The lowermost of these clear coat layers may be disposed on top of and in direct contact with the base coat layer (120). Regardless of whether the clear coat layer is applied in a single or multiple layers, the total thickness of the at least one clear coat layer may typically be about 10 to about 500 micrometers, for example, about 10 to about 200 micrometers, about 20 to about 100 micrometers, or about 30 to about 90 micrometers. In various non-limiting embodiments, all values and ranges of values, both integer values and fractional values, including and between those mentioned above, are expressly intended for use herein.

[0210] The or each clearcoat layer (130) of the article may typically be at least substantially transparent to visible light. For example, the or each clearcoat layer may be at least about 85%, at least about 90%, or at least about 95% transparent to visible light, as determined by transmission measurements (T R ) according to ASTM D1746 (2023).

[0211] Another example item is shown in the attached Fig.2. The illustrated article (1) comprises: a metal substrate (20); and a multi-layer coating (21) disposed on the metal substrate, wherein the multi-layer coating (21) comprises a primer layer (210) disposed on the metal substrate; a basecoat layer (220) comprising a color and / or visual effect-imparting compound, wherein the basecoat layer is disposed on the primer layer (210); an adhesive layer (225) disposed on the basecoat layer (220); and a clearcoat layer (230) comprising the cured product of the above-described two-part (2K) composition and disposed on the adhesive layer (225).

[0212] The adhesive layer (225) can be inserted between a basecoat layer (220) and a clearcoat layer (230) and improve their adhesion. Due to this intermediate layer, the adhesive layer (225) can typically be substantially transparent to visible light. For example, the adhesive layer (225) can be at least about 85%, at least about 90%, or at least about 95% transparent to visible light, as determined by transmission measurements (T R ) according to ASTM D1746 (2023). In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0213] In Fig.2, a single adhesion layer (225) is shown for illustrative purposes only. However, in certain embodiments, more than one adhesion layer (225) may be present. The lowermost of these adhesion layers may be disposed on top of and in direct contact with the basecoat layer (220); a clearcoat layer (230) containing the cured product of the two-part (2K) composition described above would, in these embodiments, be disposed on top of and in direct contact with the uppermost of the adhesion layers (225). The total thickness of the at least one adhesion layer may, in embodiments, be less than the total thickness of the clearcoat layer(s) (230). Alternatively or additionally, the total thickness of the at least one adhesion layer may be about 1 to about 50 micrometers, such as about 1 to about 25 micrometers, about 5 to about 25 micrometers, or about 5 to about 20 micrometers.In various non-limiting embodiments, all values and ranges of values, both integer and fractional, including and between those mentioned above, are expressly intended for use herein.

[0214] The process for producing a multi-layer coating typically comprises the following steps: i) providing a metal substrate; ii) applying a first layer of a first curable coating composition onto and in direct contact with the metal substrate; iii) at least partially curing this first layer; iv) applying a second layer of a second curable coating composition onto and in direct contact with the at least partially cured first layer; v) at least partially curing this second layer; vi) applying a third layer of a third curable coating composition onto and in direct contact with the at least partially cured second layer; and vii) at least partially curing this third layer. In an iterative process, steps vi) and vii) can be performed and repeated to apply a fourth and further layers to the metal substrate.With regard to the . Fig. 1 and Fig. 2, the first, second, third and further curable compositions provide: at least one primer layer, at least one basecoat layer, optionally at least one adhesion layer and at least one clearcoat layer as described above.

[0215] The metal substrate provided in step i) can typically be pretreated prior to step ii). Such pretreatment may comprise at least one of the following processes: cleaning the surface(s) of the metal substrate; abrading the surface(s) of the metal substrate; applying a corrosion protection layer to the metal substrate; or applying a conversion layer to the metal substrate, as mentioned above.

[0216] Cleaning serves to remove foreign matter from the surface(s) of the metal substrate. Cleaning treatments are known in the art and can be carried out in one or more steps, e.g., by using one or more of the following methods: an etching treatment with an acid suitable for the substrate and optionally an oxidizing agent; sonication; plasma treatment, including chemical plasma treatment, corona treatment, atmospheric plasma treatment, and flame plasma treatment; immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent, such as carbon tetrachloride or trichloroethylene; and water rinsing, preferably with deionized or demineralized water.In cases where an aqueous alkaline degreasing bath is used, the degreaser remaining on the surface should typically be removed by rinsing the substrate surface with deionized or demineralized water.

[0217] Independently of the cleaning of the substrate, the surface of the metal substrate (10) can be abraded. Abrading typically involves sanding, which can be performed, for example, with an orbital sander using sandpaper of a specific grit. After abrading the surface, the metal substrate can be cleaned, if necessary, to remove any dust or other contaminants generated during the abrading process.

[0218] As used in the described process, the term "at least partially cured" means that curing of the curable coating composition has been initiated and, for example, that crosslinking of the components of the composition has begun. This term encompasses any degree of cure when applying the curing conditions, from the formation of a single crosslink to a fully crosslinked state. The rate and mechanism by which the coating composition cures depends on various factors, including the constituents, the functional groups of the constituents, and the parameters of the curing conditions.

[0219] The at least partial solidification of a particular coating layer is generally an indication of curing or drying. However, drying and curing can also be indicated by other means, such as a change in the viscosity of the coating layer, an increased temperature of the coating layer, and / or a change in the transparency / opacity of the coating layer.

[0220] It may typically be that steps iv) and vi) of the application process described above are not commenced until the at least partially cured or partially dried preceding layer can substantially retain its shape when exposed to the ambient conditions. By "substantially dimensionally stable" is meant that at least about 50% by volume, and typically at least about 80 or about 90% by volume, of the at least partially cured or dried layer retains its shape and does not flow or deform when exposed to the ambient conditions for 5 minutes. Under these circumstances, gravity cannot substantially affect the shape of the at least partially cured or partially dried layer when exposed to the ambient conditions.

[0221] The shape of the at least partially dried or at least partially cured layer can typically affect whether the layer substantially retains its shape. For example, if the layer is rectangular or has another simple shape, the at least partially cured or dried layer may be more resistant to deformation even at lower degrees of curing or even lower degrees of drying than layers with more complex shapes.

[0222] In certain embodiments, the application of each subsequent layer (step iv); step vi)) occurs before an at least partially cured layer has reached a final cure state, i.e., while the layer is still "green." In such embodiments, the application of the layers can be considered "wet-on-wet," such that the adjacent layers bond together at least physically, and possibly also chemically. For example, it is possible for the constituents of the first and subsequent layers to chemically crosslink / cure across the application line, which may have beneficial effects on the longevity, durability, and appearance of the finished article. The difference between partial cure and final cure state is whether the partially cured layer can be further cured or crosslinked.While this does not preclude the presence of functional groups in the final cured state, these groups may remain unreacted due to steric hindrance or other factors.

[0223] In the aforementioned iterative process, the thickness, width, shape, and continuity of each layer can be chosen independently, so that the preceding and subsequent layers can be the same or different in one or more of these respects. For example, a particular subsequent layer can only come into contact with a portion of an exposed surface of the at least partially cured or dried previous layer. Depending on the desired shape of the coating layer, the subsequent layer can selectively build upon this layer.

[0224] The following examples are provided to illustrate the present disclosure and are not intended to limit the scope of the disclosure in any way. Examples

[0225] The following commercial products are used in the following examples: CE10P: Cardura E10P; Versatic acid glycidyl ester, available from Hexion. BYK® 345: Silicone surfactant, available from Altana. BYK® 333: Silicone-containing surface additive, available from Altana. Tinuvin® 292: Hindered amine light stabilizer, available from BASF. Tinuvin® 1130: UV absorbers from the hydroxyphenylbenzotriazole class, available from BASF. EmpolS: Dimer fatty acid, available from Henkel Corporation. Bayhydur XP2655: Hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI), available from Covestro AG. Desmodur®N 3900: Hexamethylene diisocyanate trimer, available from Covestro AG.

[0226] Unless otherwise stated, all other compounds can be purchased from Sigma Aldrich. RSE1: Reference Synthesis Example 1

[0227] In a reactor equipped with a propeller stirrer, a thermometer, a condenser, and a monomer / initiator feed system, 385 g of CE10P and 75 g of ethoxypropanol were charged and heated to approximately 150 °C. A mixture of 103 g of hydroxyethyl methacrylate, 507 g of styrene, 136 g of acrylic acid, 18 g of dicumyl peroxide, 77 g of CE10P, and 88 g of ethoxypropanol was added to the reactor over 2.5 hours while maintaining the contents at 150 °C. After the addition, the reactor contents were held for 30 minutes.

[0228] After this hold time, 175 g of hydroxyethyl methacrylate, 49 g of acrylic acid, 230 g of isobutyl methacrylate (IBMA), 7.3 g of dicumyl peroxide, and 102 g of ethoxypropanol were added over a period of 2.5 hours while maintaining the contents at 150 °C. Following this addition, the feed system was purged with 58 g of ethoxypropanol. After purging, the reactor contents were maintained at 150 °C for 2 hours.

[0229] The reactor contents were cooled to 100 °C, and 177 g of ethoxypropanol were distilled off. 54 g of dimethylaminoethanol (DMEA) were added to the contents, after which the resulting polymer mixture was diluted with 1850 g of water preheated to approximately 70 °C.

[0230] The measured properties of the resulting dispersion were as follows: solids content, 45.1 wt%; viscosity, 4500 centipoise; acid value, 27.8 mg KOH / g; and pH, 8.0. Visual stability testing revealed that the resulting aqueous dispersion showed no sedimentation for 4 weeks when stored at 60 °C.

[0231] The molecular weights of the synthesized copolymer, determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536, were: number average molecular weight (Mn) of 5300 Daltons and weight average molecular weight (Mw) of 32800 Daltons RSE2: Reference Synthesis Example 2

[0232] Dispersions of hydroxyl-functional (meth)acrylate copolymers with lower molecular weight were prepared following the procedure of Reference Synthesis Example 1 (RSE1) and increasing the initiator loading at both steps by 50% with the same loading for other materials.

[0233] The molecular weights of the synthesized copolymer, determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536, were: number average molecular weight (Mn) of 4200 Daltons and weight average molecular weight (Mw) of 17556 Daltons.

[0234] A visual stability assessment of the resulting aqueous dispersion showed sedimentation when stored at 60 °C for less than 4 weeks. Due to insufficient stability, further evaluation of the synthesized copolymer was discontinued. SE1: Synthesis Example 1

[0235] In a reactor equipped with a propeller stirrer, a thermometer, a condenser, and a monomer / initiator feed system, 385 g of CE10P and 75 g of ethoxypropanol were charged and heated to approximately 150 °C. A mixture of 103 g of hydroxyethyl methacrylate, 507 g of styrene, 136 g of acrylic acid, 18 g of dicumyl peroxide, 77 g of CE10P, and 88 g of ethoxypropanol was added to the reactor over 2.5 hours while maintaining the contents at 150 °C. After the addition, the reactor contents were held for 30 minutes.

[0236] After this hold time, 170 g of hydroxyethyl methacrylate, 47.5 g of acrylic acid, 222 g of isobutyl methacrylate (IBMA), 7.3 g of dicumyl peroxide, and 102 g of ethoxypropanol were added over a period of 2.5 hours while maintaining the contents at 150 °C. Following this addition, the feed system was purged with 58 g of ethoxypropanol. After purging, the reactor contents were maintained at 150 °C for 2 hours.

[0237] The reactor contents were cooled to 100 °C, and 190 g of ethoxypropanol were distilled off. 52 g of dimethylaminoethanol (DMEA) were added to the contents, after which the resulting polymer mixture was diluted with 1805 g of water preheated to approximately 70 °C.

[0238] The measured properties of the resulting dispersion were as follows: solids content, 45.1 wt.%; viscosity, 3800 centipoise; acid value, 27.8 mg KOH / g; and pH, 7.8. Visual stability testing revealed that the resulting aqueous dispersion showed no sedimentation for 4 weeks when stored at 60 °C.

[0239] The molecular weights of the synthesized copolymer, determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536, were: number average molecular weight (Mn) of 4300 Daltons and weight average molecular weight (Mw) of 16600 Daltons. Synthesis Example 2: Preparation of a solution of a polyester polyol (PE1)

[0240] A mixture of 911 g of trimethylolpropane, 748 g of hexahydrophthalic anhydride, and 138 g of dimer fatty acid (EmpolS) 1008 from Henkel was heated to 250 °C. Esterification was carried out with water removal until an acid number of less than 5 mg KOH / g was reached. After the reaction mixture was cooled to below 125 °C, the solids content was adjusted to 70 wt. % with 90 g of xylene and 641 g of methoxypropyl acetate.

[0241] The resulting polyester polyol had a calculated hydroxyl number of 345 mg KOH / g and an acid number of 4.5 mg KOH / g. The calculated hydroxyl functionality was 5.6, and the calculated number-average molecular weight (Mn), determined by gel permeation chromatography (GPC) using polystyrene calibration standards according to ASTM 3536, was 920 Daltons. Example 1

[0242] The dispersions described above (RSE1, SE1, PE1) were used to prepare two-part (2K) clearcoat compositions. Part a) of the two-part compositions was obtained by mixing the components listed in Table 1 below. Similarly, part b) of the two-part composition was prepared by mixing Desmodur®N 3900 and butylglycol acetate in the indicated amounts. The table describes the preparation of four reference coating compositions (RCC1-RCC4) and two coating compositions (CC1-CC2) according to the present disclosure. Table 1 Ingredient RCC1 (weight steep) RCC2 (weight steep) RCC3 (weight steep) RCC4 (weight steep) CC1 (weight steep) CC2 (weight steep) Part a) Acrylic copolymer dispersion (RSE1) 92,27 82,40 82,15 Acrylic copolymer dispersion (SE1) 92,27 82,40 82,15 Polyester Example B 5,47 5,45 5,47 5,45 2-Ethylhexane-1,3-diol 2,02 2,02 Propylene glycol methyl ether 1,31 1,31 1,01 1,31 1,01 1,31 Butylglycol acetate 0,51 0,51 0,51 0,50 0,51 0,50 White spirit 1,62 1,62 1,62 1,61 1,62 1,61 N,N-Dimethylethanolamine 0,00 0,00 0,14 0,14 0,14 0,14 Deionized water 2,02 2,02 6,58 4,54 6,58 4,54 Byk 345 0,58 0,58 0,58 0,58 0,58 0,58 Byk 333 0,19 0,19 0,19 0,19 0,19 0,19 Tinuvin 292 0,66 0,66 0,66 0,66 0,66 0,66 Tinuvin 1130 0,85 0,85 0,85 0,85 0,85 0,85 Total weight of part a) 100,00 100,00 100,00 100,00 100,00 100,00 Part b) Desmodur®N 3900 47,3 47,3 47,3 47,3 47,3 47,3 Bayhydur XP2655 23,8 23,8 23,8 23,8 23,8 23,8 Butylglycol acetate 23,7 23,7 23,7 23,7 23,7 23,7 White spirit 5,2 5,2 5,2 5,2 5,2 5,2 Total weight of part b) 100,0 100,0 100,0 100,0 100,0 100,0

[0243] The above-mentioned parts a) and b) were mixed in a weight ratio (a:b) of 100:35 to form coating compositions (RCC1-4, CC1-CC2), each composition having a molar ratio of active hydrogen atoms to -NCO groups (here, OH / NCO) of 0.7:1 to 1.4:1. The viscosity of each composition was adjusted with deionized water to a viscosity of 20 to 28 cps, which was determined at room temperature using a Brookfield CAP2000 viscometer (400 rpm, spindle No. 4). The thus-obtained clearcoats were each sprayed onto black-coated steel panels and baked at 60°C for 30 minutes. The resulting coatings were then subjected to the following evaluation tests, the results of which are shown in Table 2 below.

[0244] Wave scanning: Wave scanning, intended to simulate visual perception, was performed using a Wavescan DOI available from BYK-Gardner GmbH. The instrument provided a laser point light source that illuminated the sample at an angle of 60°. An associated detector measured the reflected light intensity at the same but opposite angle. The long-wavelength signal (structure size >0.6 mm) and the short-wavelength signal (structure size <0.6 mm) were each filtered out of the measurement signal using a mathematical filter function. The measuring device was rolled over the surface, measuring the optical profile of the surface point by point over a defined distance. The long-term ripple value given in Table 2 represents the variance of the long-wavelength signal amplitude and was normalized to a unitless value ranging from 0 to 100, where 0 represents the lowest variance (best) and 100 the highest variance (worst).Similarly, the short-term ripple value represents the variance of the short-wave signal amplitude and has been normalized to a unitless value ranging from 0 to 100, where 0 represents the lowest variance (best) and 100 the highest variance (worst).

[0245] Distinctness-of-Image (DOI): This is a measure of how clear and sharp a reflected image appears in the applied coating and was determined here using ASTM D5767-18 Standard Test Method for Instrumental Measurement of Distinctness-of-Image (DOI) Gloss of Coated Surfaces. The scale values obtained using the measurement procedures of this test method range from 0 to 100, with a value of 100 representing perfect DOI (image clarity). The further the value decreases from 100, the more the image becomes distorted.

[0246] Jacksonville Etch Value: The etch value of the clear coats was determined by exposing five (5) replicates of the clear-coated steel panels (30 cm x 30 cm) to an exposure site on Blount Island, Jacksonville, Florida (USA). Exposure lasted from late May to late August. Defects were rated using a grading scale ranging from 1 (no visible etching) to 10 (severe etching), as described in GM Material Specification 9984157 (2009). The grades of the five replicates were averaged to obtain the etch values listed in Table 2 below. Table 2 Tested property RCC1 RCC2 RCC3 RCC4 CC1 CC2 Image sharpness (DOI)- 95,5 95,8 96,5 96,5 96,7 96,9 Long-term ripple value 4 3,8 4,8 1,7 3,4 1,5 Short-term ripple value 2,4 2,1 2,2 1,6 2,0 1,4 Jacksonville Etch Test: 7,5 6,9 7,0 7,2 6,1 6,4

[0247] Compared to the reference coating compositions RCC1 and RCC2, the addition of the polyester resin to CC1 resulted in an improved appearance, as shown by the lower shortwave value and the higher DOI value in Table 2. In addition, CC1 exhibited improved Jacksonville etch resistance.

[0248] Compared to the reference coatings RCC3 and RCC4, the methacrylate copolymers used in CC1 and CC2 resulted in improved appearance, as shown by the lower shortwave value and higher DOI value in Table 2. Furthermore, CC1 and CC2 exhibited improved Jacksonville etch resistance.

[0249] The presence of the low molecular weight diol in combination with the polyester resin in the CC2 coating composition promotes an improvement in both long-term and short-term waviness values without significantly affecting the image sharpness results or etch resistance.

[0250] It is understood that various changes and modifications to the exemplary embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. It is to be understood that the features of the dependent claims may be embodied in the compositions and methods of any of the independent claims.

[0251] Many modifications and other embodiments of the disclosure set forth herein will occur to one skilled in the art to which this disclosure belongs once they have received the teachings of the foregoing description. It is therefore to be understood that the disclosure is not limited to the specific embodiments, and that modifications and other embodiments are intended to be included within the scope of the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2012237688A1

[0146] US 6,129,244

[0194] US 8,313,006

[0194] Cited non-patent literature

[0000] DIN 53240

[0022] Kohlerin J. Am. Chem. Soc., 49, 3181 (1927)

[0023]

Claims

[1] Two-part (2K) water-based coating composition comprising: Water; a) a binder part comprising: (a1) at least one hydroxyl-functional (meth)acrylate copolymer; and (a2) at least one non-aromatic polyester having active hydrogen groups; and b) a crosslinking part comprising: at least one polyisocyanate compound with pendant -NCO groups, wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is 5:1 to 1:5; wherein the non-aromatic (a2) polyester has a number average molecular weight (Mn) of about 500 to about 5000 Daltons, an acid number of about 0 to about 30 mg KOH / g, a calculated hydroxyl number of about 100 to about 600 mg KOH / g, and a calculated hydroxyl functionality of about 2 to about 8; and wherein the (a1) (meth)acrylate copolymer is the reaction product of monomers in a monomer mixture comprising, based on the total weight of the monomers: from about 20 to about 60 wt.% of i) at least one hydroxyl-functional adduct of a monoepoxy ester and an unsaturated carboxylic acid; from about 10 to about 30 wt.% ii) of at least one hydroxyl-functional unsaturated monomer other than component i); from about 2 to about 6 wt.% iii) at least one unsaturated acid-functional monomer; and from about 20 to about 60 wt.% iv) of at least one (meth)acrylate monomer of the formula MA: H2C=CG a CO2R a (MA) where: Ga represents hydrogen, halogen or methyl; and R a for: 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 to about 15 wt.% v) of at least one vinyl aromatic monomer; and from about 0 to about 20 wt.% vi) at least one polymerizable unsaturated monomer different from i) to v). [2] The coating composition of claim 1, wherein the weight ratio of the solids of (a1) to the solids of (a2) is about 100:1 to about 100:

35. [3] Coating composition according to claim 1 or 2 having a volatile organic compound (VOC) content, measured according to ISO 11890-2: 2006, of at most about 420 g / l. [4] Coating composition according to any one of claims 1 to 3, wherein in the formula (MA): R a for C1-C 18 -alkyl or C3-C 18 -cycloalkyl. [5] A coating composition according to any one of claims 1 to 4, wherein the (meth)acrylate monomer of formula (MA), when homopolymerized, yields a homopolymer having a glass transition temperature (Tg) greater than about 30°C. [6] The coating composition of claim 5, wherein the at least one (meth)acrylate monomer is selected from: cyclohexyl (meth)acrylate; 3,3,5-trimethylcyclohexyl (meth)acrylate; isobornyl (meth)acrylate; norbornyl (meth)acrylate; dihydrodicyclopentandienyl (meth)acrylate; 4-tert-butylcyclohexyl (meth)acrylate; and mixtures thereof. [7] A coating composition according to any one of claims 1 to 6, wherein v) is present in an amount of about 4 to about 14 wt.% of the total weight of monomers in the monomer mixture. [8] The coating composition of claim 7, wherein v) is present in an amount of about 10 to about 14 weight percent of the total weight of monomers in the monomer mixture. [9] Coating composition according to any one of claims 1 to 8, wherein the at least one vinyl aromatic monomer of v) has the following formula (VA): where: R 1 represents H or C1-C4 alkyl; every R 2 independently represents hydrogen or C1-C4 alkyl; Ar is unsubstituted phenyl or phenyl substituted by 1 to 5 substituents, each substituent independently being halogen or C1-C4 alkyl; and n stands for an integer from 0 to 4. [10] Coating composition according to claim 9, wherein: R 1 represents H or methyl; every R 2 independently represents H or methyl; Ar is unsubstituted phenyl or phenyl substituted by 1 to 5 substituents, each substituent independently being halogen or C1-C4 alkyl; and n stands for 0 or 1. [11] A coating composition according to claim 9 or 10, wherein v) 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. [12] Coating composition according to any one of claims 1 to 11, wherein at least one monomer of the monomer mixture has the following formula AM1: R 4 -C(H)=C(R 5 )-A-(R 6O ) [a] -R 7 (AM1) where: R 4 represents H, methyl, CO2H or CH2CO2H; R 5 represents hydrogen, halogen or methyl; A for -CH2C(O)O-, -C(O)O-, -O-, -CH2O-, -CH2C(O)N-, -C(O)N-, -CH2-, -OC(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-; every R 6 independently represents C2-C4 alkylene; [a] has a value of about 5 to about 100; R 7 for 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 R 8 stands for -CH2- or -(C)(CH3)2-. [13] Coating composition according to claim 12, wherein: R 4 represents H, methyl, CO2H or CH2CO2H; R 5 represents hydrogen, halogen or methyl; A stands for -CH2C(O)O- or -C(O)O-; every R 6 independently represents C2-C4 alkylene; [a] has a value of about 10 to about 30; and R 7 for 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. [14] Coating composition according to claim 12 or 13, wherein: R 4 represents H, methyl, CO2H or CH2CO2H; R 5 represents hydrogen, halogen or methyl; A stands for -C(O)O-; every R 6 independently represents C2-C3 alkylene; [a] has a value of about 10 to about 30; and R 7 for C6-C 30 -Alkyl, C6-C 30 -hydroxyalkyl or C6-C 30 -Aminoalkyl. [15] A coating composition according to any one of claims 12 to 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 number of moles of ethoxylation and has a value of about 10 to about 30. [16] Coating composition according to any one of claims 1 to 15, wherein the (a1) hydroxyl-functional (meth)acrylate copolymer is prepared from the monomer mixture by a two-stage polymerization process. [17] Coating composition according to any one of claims 1 to 16, wherein the (a1) hydroxyl-functional (meth)acrylate copolymer is prepared from the monomer mixture by a skew-feed polymerization process with at least two feed monomer streams; and wherein a feed stream further comprises: I) from about 60 to about 100 wt.% of the total amount of i) in the monomer mixture; II) from about 0 to about 60 wt.% of the total amount of ii) in the monomer mixture; III) from about 0 to about 30 wt.% of the total amount of iii) in the monomer mixture; and IV) from about 0 to about 80 wt.% of the total amount of iv) in the monomer mixture; V) from about 0 to about 100 wt.% of the total amount of v) in the monomer mixture; and VI) from about 0 to about 100 wt.% of the total amount of vi) in the monomer mixture, wherein the remaining one or more feed streams comprise the remainder of i) to vi). [18] A coating composition according to any one of claims 1 to 17, wherein the (a2) non-aromatic polyester comprises: a number average molecular weight (Mn) of about 500 to about 1500 Daltons; an acid number of about 0 to about 30 mg KOH / g; a calculated hydroxyl number of about 250 to about 400 mg KOH / g; and a calculated hydroxyl functionality of about 4 to about 8. [19] Coating composition according to any one of claims 1 to 18, wherein the (a2) non-aromatic polyester is obtained by the polycondensation reaction of: at least one hydroxyl-functional component (a2h); at least one carboxyl-functional component (a2c); and optionally at least one hydroxycarboxylic acid component (a2hc), wherein a stoichiometric excess of hydroxyl groups to carboxyl groups is used in the polycondensation reaction. [20] Coating composition according to claim 19, wherein: the hydroxyl-functional component (a2h), based on the weight of the hydroxyl-functional component, comprises: from about 75 to about 100% by weight of at least one polyol having 3 to 6 hydroxyl groups; and from about 0 to about 25% by weight of at least one diol; and the carboxyl-functional component (a2c), based on the weight of the carboxyl-functional component, comprises: from about 75 to about 100 wt.% of at least one dicarboxylic acid; and from about 0 to about 25 wt.% of at least one monocarboxylic acid. [21] The coating composition of claim 20, wherein the at least one dicarboxylic acid comprises a dimer fatty acid in an amount of about 5 to about 50 wt.% based on the weight of the carboxyl-functional component. [22] A coating composition according to any one of claims 1 to 21, wherein part a) further comprises up to 20% by weight, based on the weight of (a1), of the following: (a3) at least one (meth)acrylate polymer having active hydrogen groups which is different from the hydroxyl-functional (meth)acrylate polymer(s) of (a1), wherein (a3) has a water solubility at about 20°C of less than about 6 g / 100 ml of water. [23] A coating composition according to claim 22, wherein the (meth)acrylate polymer of (a3) comprises: a calculated hydroxyl number of about 100 to about 600 mg KOH / g, an acid number of about 0 to about 35 mg KOH / g; and a number average molecular weight of about 1000 to about 4000 Daltons. [24] Coating composition according to any one of claims 1 to 23, wherein the binder part a) further comprises: (a4) at least one non-polymeric, acyclic polyol having a weight-average molecular weight (Mw) of less than about 300 Daltons and a water solubility at about 20°C of less than about 6 g / 100 ml of water, wherein (a4) is present in an amount of up to 10 wt.%, based on the weight of the binder part a). [25] Coating composition according to any one of claims 1 to 24, wherein the binder part a) further comprises: (a5) at least one non-polymeric, cycloaliphatic polyol having a weight average molecular weight (Mw) of less than about 300 Daltons, wherein (a5) is present in an amount of up to 10 wt.%, based on the weight of the binder part a). [26] Coating composition according to any one of claims 1 to 25, wherein the polyisocyanate compound of the crosslinking part b) comprises 2 to 5 functional -NCO groups. [27] A coating composition according to any one of claims 1 to 26, wherein the molar ratio of active hydrogen atoms to -NCO groups in the composition is about 3:1 to about 1:

3. [28] A cured product obtained from the aqueous coating composition according to any one of claims 1 to 27. [29] Subject matter, comprising: a metal substrate; and a multilayer coating disposed on the metal substrate, wherein at least one layer of the multilayer coating comprises the cured product of claim 28. [30] The article of claim 29, wherein the multilayer coating comprises: a primer layer disposed on and in direct contact with the substrate; at least one basecoat layer comprising a color and / or visual effect-imparting compound, wherein at least one basecoat layer is arranged on the primer layer and in direct contact therewith; and a clear coat layer comprising the cured product of claim 28 and disposed on and in direct contact with at least one base coat layer.

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