Controlled cure coating composition

Abstract

Disclosed are coating compositions comprising: one or more polyurethane resins containing thiol functional groups and dispersible groups; one or more crosslinkers comprising functional groups that react with the thiol functional groups; a basic catalyst; and a volatile acid. Also disclosed are methods of making and using such coating compositions.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to the following U.S. provisional patent applications filed under 35 USC § 119: 63 / 656,264, filed March 14, 2024, entitled “High Solids Coating Composition”; 63 / 565,239, filed March 14, 2024, entitled “Controlled Curing Coating Composition”; and 63 / 767,190, filed March 5, 2025, entitled “Emulsifiable Resin”, all of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to methods and systems for controlling the curing rate of coating compositions for application to a substrate to form a coating. Background Technology

[0004] Coatings can be applied to a variety of substrates to provide color and other visual effects, corrosion resistance, abrasion resistance, chemical resistance, etc. In addition, various types of coatings (such as coatings applied to packaging, automobiles, and a wide variety of substrates) can be formed from compositions that can be baked and formed at relatively low curing temperatures (e.g., 20°C to 80°C). Summary of the Invention

[0005] This disclosure relates to coating compositions comprising one or more polyurethane resins containing thiol functional groups and dispersible groups; one or more crosslinking agents containing functional groups that react with the thiol functional groups in the polyurethane resins; a basic catalyst; and a volatile acid. Methods for preparing and using such coating compositions are also disclosed. Detailed Implementation

[0006] For the purposes of the following detailed description, it should be understood that this disclosure may take various alternative variations and sequences of steps, unless the contrary is expressly indicated. Furthermore, except in any operational instance or where otherwise indicated, all figures representing the quantities of ingredients, such as those used in this specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary according to the desired characteristics to be obtained through this disclosure. At least, and not in an attempt to limit the application of the doctrine of equivalence to the scope of the claims, each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques.

[0007] I. Definition

[0008] Although the numerical ranges and parameters described in this disclosure are approximate, the values ​​presented in specific examples are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation present in its corresponding test measurement.

[0009] Furthermore, it should be understood that any numerical range described herein is intended to include all subranges included therein. For example, the range “1 to 10” is intended to include all subranges between (and including) the stated minimum value of 1 and the stated maximum value of 10, that is, a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0010] In this application, unless otherwise specifically stated, the use of the singular includes the plural, and the plural encompasses the singular. Furthermore, in this application, unless otherwise explicitly stated, the use of "or" means "and / or," even if "and / or" can be explicitly used in certain situations. Further, in this application, unless otherwise specifically stated, the use of "a / an" means "at least one / a kind." For example, "a" polymer, "a" acid, etc., refer to one or more of these items.

[0011] Unless otherwise specified, the ambient temperature and pressure conditions are ambient temperature (20 to 25°C, such as 23°C) and standard pressure of 101.3 kPa (1 atmosphere), with relative humidity in the air of 35% to 75%, such as 55%.

[0012] When used herein, “acid value” indicates the quantitative acidity of a given chemical substance based on the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize the acidic component in 1 gram of nonvolatile component and can be determined according to ASTM D4662-15.

[0013] As used herein, “photochemical radiation” refers to electromagnetic radiation capable of initiating photochemical reactions, such as, but not limited to, UVB and UVC radiation (180 to 315 nm) and near-UV radiation energy in the range of 320 to 380 nm (or 400 nm).

[0014] As used herein, the term “active hydrogen” refers to hydrogen in primary or secondary amine functional groups, thiol functional groups, and / or hydroxyl functional groups.

[0015] As used in this article, the term "ASTM" refers to the publications of ASTM International in West Constable Hawken, Pennsylvania.

[0016] As used herein, the terms “main chain” and “polymer main chain” refer to the main chain of monomer repeating units that make up the polymer main chain.

[0017] As used herein, unless otherwise stated, the terms “base” and “basic” refer to substances that can neutralize acids by reacting with hydrogen ions.

[0018] As used herein, the term "primer" refers to a coating applied over a primer layer (another primer); and / or applied directly to a substrate, optionally including components that affect color and / or provide other visual impact (such as colorants). A clear coat may be applied over the primer.

[0019] As used herein, the term "transparent coating" refers to a coating that is at least substantially transparent, colored, or completely transparent and often does not contain colorants. The term "substantially transparent" means a coating in which the surface beyond the coating is at least partially visible to the naked eye when viewed through the coating. The term "completely transparent" means a coating in which the surface beyond the coating is entirely visible to the naked eye when viewed through the coating.

[0020] As used herein, the term "coating" refers to an finished product obtained by applying one or more coating compositions to a substrate and, as a non-limiting example, by curing. Primer coatings, undercoatings, or colored and clear coats may comprise a portion of a coating film. As used herein, the term "coating" is used to refer to the result of applying one or more coating compositions to a substrate in one or more applications of such coating compositions. As a non-limiting example, a single coating referred to as a "colored coating" or "topcoat" may be used to provide the function of both a primer and a clear coat, and may comprise the result of two or more applications of a colored coating composition.

[0021] As used herein, the term "colorant" refers to any substance that imparts color and / or other opacity and / or other visual effects to a coating composition, and may include, but is not limited to, dyes and pigments.

[0022] As used herein, the transitional term “comprising” (and other equivalent terms such as “containing” and “including”) is “open-ended” and open to include unspecified substances. Although described as “comprising”, the terms “consistently composed of” and “composed of” are also within the scope of this disclosure.

[0023] As used herein, the interchangeable terms “crosslinker” and “crosslinking agent” refer to a molecule or polymer containing functional groups that react with crosslinking functional groups of the polymer and / or resin in the coating composition.

[0024] As used herein, the term "crosslinking functional group" and similar terms refer to functional groups or combinations thereof located in the main chain of a polymer, typically in groups attached to the side of the main chain of the polymer, or terminated on the main chain of the polymer, wherein such functional groups are capable of reacting with other crosslinking functional groups or individual crosslinking agents during curing to produce crosslinked coatings.

[0025] As used herein, the terms “curable,” “curable,” etc., when used in conjunction with a coating composition, mean that at least a portion of the components constituting the coating composition are polymerizable and / or crosslinkable via a condensation reaction when exposed, as a non-limiting example, to higher temperatures or ultraviolet radiation.

[0026] As used herein, the term "dispersible group" refers to a group in a molecule that allows the molecule to be uniformly dispersed in a solvent or continuous phase, but does not necessarily require complete fusion with the solvent or continuous phase under ambient conditions. A non-limiting example of a "dispersible group" is a "water-soluble group," which refers to a group that allows the molecule to dissolve and fuse in water under ambient conditions to form a homogeneous solution.

[0027] As used herein, the term "dye" refers to a colored substance, and in many cases to an organic compound, which can be chemically bonded to another component in a substrate or coating composition.

[0028] As used herein, the term "electron-withdrawing group" and similar terms refer to a group that reduces the electron density in adjacent atoms of a molecule by means of the carbon atom to which it is bonded.

[0029] As used herein, the term "epoxy group" refers to a molecule containing one or more glycidyl or ethylene oxide groups.

[0030] As used herein, the term "film-forming" material refers to a film-forming component of a coating composition and may include polymers, resins, crosslinking agents, or any combination thereof as film-forming components of a coating composition. As a non-limiting example, film-forming materials may be dried or cured by exposure to elevated temperatures (e.g., above 40°C), photochemical radiation, or under ambient conditions.

[0031] As used herein, the term "hydroxyl-functionalized compound" refers to an organic compound containing one or more hydroxyl (-OH) groups.

[0032] As used herein, the term "isocyanate reactive compound" refers to a molecule containing at least one group that reacts with an isocyanate group, such as, but not limited to, hydroxyl, primary or secondary amine and / or thiol.

[0033] Unless otherwise specified, as used herein, the term "molecular weight" refers to the weight-average molecular weight determined by gel permeation chromatography (GPC) using appropriate polystyrene standards. If a number-average molecular weight is specified, the weight is determined by the same GPC method while calculating the numerical average of the polymer molecular weight distribution data obtained therefrom. "Number-average molecular weight" is the total weight of the material divided by the number of molecules in the material and can be determined using gel permeation chromatography. Unless otherwise specified, the units for both "weight-average molecular weight" and "number-average molecular weight" are g / mol.

[0034] As used herein, the term "single coating" refers to a coating that can be a single coating used to modify the surface of a substrate and which is not subsequently coated with another coating (such as a clear coat), such as a topcoat.

[0035] As used in this article, the term "monomer" refers to a molecule that can react with other monomer molecules through a polymerization process to form a larger polymer chain or three-dimensional network.

[0036] As used herein, the terms "multi-component," "multi-K," and "multi-package" refer to coating compositions comprising a first component containing a crosslinkable resin, a second component containing a crosslinking agent, and additional components, which may or may not contain a crosslinkable resin or crosslinking agent, wherein these components are stored separately prior to use. The crosslinkable resin and crosslinking agent are capable of reacting when combined to form a thermosetting composition. When a multi-component coating composition does not contain additional components, the coating composition is a two-component or 2-K coating composition.

[0037] As used herein, the term "NCO functional prepolymer" refers to a polymeric intermediate used to prepare the polyurethane resin described herein containing at least one terminal isocyanate (NCO) group.

[0038] As used herein, the term "olefinic group" refers to one or more pairs of carbon atoms linked by a double bond in a compound containing hydrogen and carbon.

[0039] As used herein, the terms “single-component,” “1-K,” and “1-package” refer to a coating composition in which all coating components remain in the same package after manufacture, during transport and storage, and in the same container after manufacture, during storage, etc., and remain stable (substantially unreactive or gelling) for more than one month, such as more than three months, more than six months, more than nine months, or more than twelve months, at 40 to 120℉ (4 to 49°C) and at 0 to 95% relative humidity.

[0040] As used herein, the term "organic solvent" refers to a carbon-based substance that can dissolve or disperse other substances.

[0041] As used herein, the term "pigment" refers to a colored material, typically an inorganic compound, that is completely or almost insoluble in a solvent at room temperature.

[0042] As used herein, “polyol” refers to a compound having two or more hydroxyl groups, such as two, three or four hydroxyl groups.

[0043] As used herein, the prefix "poly" refers to two or more. By way of non-limiting examples, polyisocyanate refers to a compound containing two or more isocyanate groups, and polyol refers to a compound containing two or more hydroxyl groups.

[0044] As used herein, the term "polyisocyanate" refers to a compound having two or more isocyanate groups, such as two, three or four isocyanate groups, and may include both blocked (or capped) polyisocyanates and unblocked polyisocyanates.

[0045] As used herein, the term "polymer" includes homopolymers (formed from a single monomer) and copolymers formed from two or more different monomers or containing two or more different repeating units. Furthermore, the term "polymer" includes prepolymers and oligomers.

[0046] As used herein, “precision application” refers to applying a coating composition to a substrate using a high-efficiency applicator that can apply the coating composition to at least a portion of the substrate without overspraying, with a transfer efficiency greater than 85% as a non-limiting example.

[0047] As used herein, the term "primer coating" refers to a base coat that can be applied to a substrate to prepare a surface for the application of a protective or decorative coating composition.

[0048] As used herein, “resin solids” refers to the non-volatile organic components of the binder or film-forming components that constitute the composition, excluding inorganic components such as pigments and fillers. As used herein, a weight percentage based on “resin solids” means the amount of the component based on the total weight of the binder or film-forming components of the composition.

[0049] As used herein, the term "solid" refers to the non-volatile portion of the composition.

[0050] As used herein, the term “substrate” refers to the surface of an article to be coated, and may also refer to a coating that has previously been applied to the article, which is also considered a substrate.

[0051] As used herein, the term "thermosetting" refers to a polymer or resin having functional groups that react with crosslinking agents or functional groups in another polymer or molecule to form a network material, irreversibly transforming a "soft" polymer into a more rigid form. In many cases, thermosetting refers to a resin that is irreversibly "cured" after curing or crosslinking, in which the polymer chains of the resin are linked together by covalent bonds. Once cured or crosslinked, thermosetting resins will not melt when heat is applied and are insoluble in solvents.

[0052] As used herein, the term “thermoplastic” refers to polymers and resins that are not covalently bonded and therefore can undergo liquid flow upon heating and are soluble in certain solvents.

[0053] As used herein, the term "topcoat" refers to the topmost coating deposited on top of another coating, such as an undercoat, to provide a protective and / or decorative layer.

[0054] As used herein, the terms “total solids” or “solids” or “solids content” refer to the solids content as determined according to ASTM D2369-20.

[0055] As used herein, the terms "two-component," "2-K," and "2-package" refer to a coating composition comprising a first component containing a crosslinkable resin and a second component containing a crosslinking agent, wherein the first and second components are stored separately until just before use. The crosslinkable resin and the crosslinking agent are capable of reacting when combined to form a thermosetting composition.

[0056] As used herein, the term "vehicle" is used in its broadest sense and includes all types of vehicles, such as, but not limited to, automobiles, vans, SUVs, trucks, semi-trailer trucks; tractors, buses, vans, golf carts, motorcycles, bicycles, rail vehicles, trailers, all-terrain vehicles (ATVs); pickup trucks; heavy mobile equipment, such as bulldozers, mobile cranes, and earthmoving machinery; aircraft; boats; ships; and other modes of transport, including but not limited to all types of aircraft, spacecraft, water vehicles, and ground vehicles.

[0057] As used herein, the term “volatile” refers to a material that is readily vaporized (with a vapor pressure of at least 1 mm Hg) under ambient and / or curing conditions.

[0058] As used herein, the term "water-dispersible group" refers to a group in a molecule that allows the molecule to be uniformly dispersed in water but does not necessarily have to be completely fused with water under ambient conditions. A subset of "water-dispersible groups" is "water-soluble groups," which refers to groups that allow the molecule to dissolve and fuse in water under ambient conditions to form a homogeneous solution.

[0059] As used in this article, the phrase “weight%” refers to a percentage of weight.

[0060] This disclosure relates to coating compositions comprising one or more polyurethane resins containing thiol functional groups and dispersible groups; one or more crosslinking agents containing functional groups that react with the thiol functional groups; a basic catalyst; and a volatile acid. The volatile acid, such as the amount used, can control the curing rate of the coating composition. The specific acid used can vary depending on the curing conditions to be applied.

[0061] II. Polyurethane resin

[0062] The polyurethanes disclosed herein and their preparation methods are well known in the art. Polyurethanes can be prepared by reacting an isocyanate reactive compound (such as, but not limited to, hydroxyl-functionalized compounds, thiols, or mercapto-functionalized compounds and / or primary or secondary amines) with a polyisocyanate such that the ratio of NCO to isocyanate reactive groups is greater than 1:1, to generate an NCO-functionalized prepolymer. The terminal isocyanate can then react to generate terminal thiol (-SH) groups. The thiol-functionalized polyurethane polymer can then be used in a curable composition. Optionally, the thiol-functionalized polyurethane can be dissolved or dispersed in water before or during its use in a curable composition.

[0063] The number-average molecular weight (Mn) of the polyurethane resin can be 400, 500, 1000 to 2000, 3000, 4000, or any range using any two of the foregoing values ​​as endpoints, such as 400 to 4000, 500 to 3000, or 1000 to 2000, as determined by gel permeation chromatography using polystyrene standards.

[0064] A. NCO functional prepolymer

[0065] NCO-functional prepolymers can be formed from compounds containing active hydrogen and excess polyisocyanate. The NCO-functional prepolymers of this disclosure can be polyurethanes, polyureas, poly(thiourethane), and / or combinations thereof. Polyurethanes can be formed in a first stage from a polyol and excess polyisocyanate to form a prepolymer. Polyureas can be formed in a first stage from a polyamine and excess polyisocyanate to form a prepolymer. Poly(thiourethane) can be formed in a first stage from a molecule having one or more thiol or mercaptan groups and excess polyisocyanate to form a prepolymer. NCO prepolymers can be formed from a combination of polyols, polyamines, polythiols, and / or compounds containing two different active hydrogens with excess isocyanate. NCO-functional prepolymers can be prepared using any combination of the above reactants. The prepolymer can then be further modified with non-tertiary amines, polyethers, thiol or mercaptan compounds, and / or acid-containing compounds to form the polyurethane resin according to this disclosure.

[0066] i. Polyisocyanate

[0067] The NCO-functional prepolymers disclosed herein can be derived from polyisocyanates, such as diisocyanates, and, as a non-limiting example, can be reacted with polyols and / or acid-containing hydroxyl functional compounds and / or other isocyanate reactive compounds.

[0068] Suitable polyisocyanates can be aliphatic, aromatic, alicyclic, or heterocyclic isocyanates. Suitable aliphatic isocyanates may include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylidene diisocyanate, 1,2-butylidene diisocyanate, 2,3-butylidene diisocyanate, and 1,3-butylidene diisocyanate; cycloalkylene compounds, such as 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,2-cyclohexane diisocyanate, and isophorone diisocyanate; aromatic compounds, such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylene diisocyanate, 1,5-naphthalene diisocyanate, and 1,4-naphthalene diisocyanate; and aliphatic-aromatic compounds, such as 4,4'-diphenylmethane diisocyanate. Esters, 2,4- or 2,6-tolyl diisocyanates or mixtures thereof, 4,4'-toluidine diisocyanate, tetramethylxylene diisocyanate and xylene diisocyanate; nucleosubstituted aromatic compounds, such as o-anisidine diisocyanate, 4,4'-diphenyl ether diisocyanate and chlorodiphenylene diisocyanate; triisocyanates, such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanobenzene, hexamethylene diisocyanate isocyanurate trimer and 2,4,6-triisocyanotoluene; and tetraisocyanates, such as 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate; polymeric polyisocyanates, such as tolyl diisocyanate dimers and trimers, etc.

[0069] Suitable diisocyanates also include those having a single aromatic or alicyclic ring, such as isophorone diisocyanate (IPDI), tetramethylxylene diisocyanate (TMXDI), 4,4'-methylene dicyclohexyl diisocyanate (H12MDI), 1,6-hexamethylene diisocyanate (HDI), 1,3-bis(isocyanomethyl)cyclohexane, 1,5-diisocyano-2-methylpentane, 1,6-diisocyano- 2,2,4-Trimethylhexane, 1,6-Diisocyanate-2,4,4-Trimethylhexane, 1,4-Diisocyanate-butanone, trimethylhexamethylene diisocyanate, 1,8-Diisocyanate-octane, 1,12-Diisocyanate-dodecane, 1,8-Diisocyanate-2,4-Dimethyloctane, 1,4-bis(isocyanate-methyl)cyclohexane, trans-1,4-cyclohexene diisocyanate, and 2,4-Diisocyanate-1-methylcyclohexane.

[0070] Other suitable aliphatic diisocyanates may also include: methyl-2,6-diisocyanohexanoate, bis(isocyanomethyl)cyclohexane, 1,3-bis(isocyanomethyl)cyclohexane, 2,5(6)-bis(isocyanomethyl)cyclo[2.2.1.]heptane, 1,3,3-trimethyl-1-(isocyanomethyl)-5-isocyanocyclohexane, octahydro-4,7-methylbridge-1H-indene diisocyanate and 1,1'-methylenebis(4-isocyanocyclohexane).

[0071] Polyurethane can be derived from a mixture containing 20% ​​or 25% or 30% to 40% or 50% or 55% by weight, or any range (such as 20% to 55% by weight, such as 25% to 50% or 30% to 40% by weight) of polyisocyanate, or any range (such as 20% to 55% by weight, or 25% to 50% or 30% to 40% by weight) using any two of the foregoing values ​​as endpoints, wherein the weight percentage is based on total resin solids.

[0072] When forming a prepolymer, the molar ratio of the isocyanate functional group of the polyisocyanate to the isocyanate reactive group of the acid-containing polyol and / or the isocyanate reactive group of the non-acid-containing polyol can be greater than 1.

[0073] ii. Isocyanate reactive compounds

[0074] The NCO-functionalized prepolymers disclosed herein can be formed from isocyanate-reactive compounds, such as primary or secondary amine functional compounds, thiol functional compounds, and hydroxyl functional compounds that react with the isocyanate of the NCO-functionalized prepolymer. The hydroxyl functional compounds can be, but are not limited to, hydroxyl-functionalized polyesters, polycarbonates, polyethers, polyetheramines, such as those available from Huntsman International LLC under the trade name Jeffamine, or acrylic polymers. The thiol functional compounds can include, but are not limited to, C2-C... 20 Alkyl dithiols, such as dodecanedithiols.

[0075] The hydroxyl group in a hydroxyl-functionalized compound can be linked by a bridging group selected from the following: alkylene group; alkenylene group; ynylene group; or arylene group. Hydroxyl-functionalized compounds may lack an acid group, such as non-acidic polyols.

[0076] Hydroxyl-functionalized compounds include, but are not limited to, the following: alkylene glycols, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, hexanediol, polyethylene glycol, polypropylene glycol, and neopentyl glycol; hydrogenated bisphenol A; cyclohexanediol; propylene glycols, including 1,2-propanediol, 1,3-propanediol, butylethylpropanediol, 2-methyl-1,3-propanediol, and 2-ethyl-2-butyl-1,3-propanediol; butanediols, including 1,4-butanediol, 1,3-butanediol, etc. Diols and 2-ethyl-1,4-butanediol; pentanediols, including trimethylpentanediol and 2-methylpentanediol; cyclohexanediol; hexanediols, including 1,6-hexanediol, caprolactone diol (such as the reaction product of ε-caprolactone and ethylene glycol), hydroxyalkylated bisphenols; polyether diols, such as poly(oxytetramethylene) diol and polytetrahydrofuran; trimethylolpropane; pentaerythritol; dipentaerythritol; trimethylolethane; trimethylolbutane; dimethylolcyclohexane; glycerol, etc., or combinations thereof.

[0077] Hydroxyl functional compounds can be acid-free polyols, meaning that polyols lack acid groups.

[0078] Hydroxyl-functionalized polyesters, poly(meth)acrylates, and polycarbonates can be suitable hydroxy-functionalized compounds that react with polyisocyanates in the formation of polyurethane resins. As used herein, the term "(meth)acrylate" refers to both acrylate and the corresponding (meth)acrylate. Poly(meth)acrylates can be any suitable poly(meth)acrylate or mixtures thereof. Poly(meth)acrylates may include di(meth)acrylates, tri(meth)acrylates, tetra(meth)acrylates, and / or one or more other olefinically unsaturated free radical polymerizable monomers. Mixtures of poly(meth)acrylate monomers, including mono, di, tri, and / or tetra(meth)acrylates, may also be used.

[0079] Hydroxyl-functionalized compounds include, but are not limited to, the following: ethylene glycol; 1,2-propanediol; 1,3-propanediol; 1,2-butanediol; 1,3-butanediol; 1,4-butanediol; but-2-ene 1,4-diol; 2,3-butanediol; 2-methyl 1,3-propanediol; 2,2'-dimethyl 1,3-propanediol (neopentyl glycol); 1,5-pentanediol; 3-methyl 1,5-pentanediol; 2,4-diethyl 1, 5-Pentanediol; 1,6-Hexanediol; 2-Ethyl-1,3-Hexanediol; Diethylene glycol; Triethylene glycol; Dipropylene glycol; Tripropylene glycol; 2,2,4-Trimethylpentane-1,3-diol; 1,4-Cyclohexanediol; Tricyclodecanediol; 2,2,4,4-Tetramethylcyclobutane-1,3-diol; Isosorbide; 1,4-Cyclohexanediol; 1,1'-Isopropylidene-bis(4-cyclohexanol); and mixtures thereof.

[0080] Suitable hydroxyl-functionalized compounds may include polyether glycols, such as Terathane® 250 and Terathane® 650 available from Invista or PolyTHF® polyether glycol available from BASF.

[0081] Polyurethane may include hydroxyl functional compounds in amounts of 15 wt%, 20 wt%, 25 wt% to 30 wt%, 35 wt%, 40 wt%, or any range (such as 15 wt% to 40 wt%, 20 wt% to 35 wt%, or 25 wt% to 30 wt%) using any two of the foregoing values ​​as endpoints, wherein the wt% is based on total resin solids.

[0082] B. Polyurethanes containing thiol functional groups

[0083] The polyurethane resin disclosed herein contains a thiol functional group. Polythiol or mercapto compounds, as well as compounds containing both thiol or mercapto groups and hydroxyl functional groups, can be suitable compounds that can react with the isocyanate groups of NCO-functional prepolymers during the formation of the polyurethane resin.

[0084] Suitable polythiols or polythiol compounds may include, but are not limited to, C2-C 20 Alkyl dithiols, such as dodecanedithiols, trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(2-mercaptopropionate), 1,8-dimercapto-3,6-dioxaoctane, thiol-terminated polyethers, pentaerythritol tetra-3-mercaptopropionate, pentaerythritol tetra-2-mercaptoacetate, 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol, 2,3-dithio(2-mercapto)-1-propanethiol, and thiol-terminated polyethers.

[0085] Suitable compounds including both thiol or mercapto groups and hydroxyl functional groups may include, but are not limited to, dithiothreitol; thiol and hydroxyl functionalized polyesters, poly(meth)acrylates and polycarbonates; 2,3-dimercapto-1-propanol; and compounds according to the following formula:

[0086] (HS) x -R 1 y -(OH) z

[0087] Where R 1 It can be C2, such as C3 or C6 to C 20 A straight-chain, branched, or cyclic aliphatic and / or aromatic group or polymer backbone, which may contain O, N, and / or S heteroatoms, wherein y is 1 to 100, such as 1 to 50 or 1 to 25; x can be 1 to 50, such as 1 to 30 or 1 to 20 or 1 to 10 or 1 to 5, wherein the SH group is bonded to a carbon atom; and z can be 0 to 60, such as 1 to 40 or 1 to 30 or 1 to 20 or 1 to 10 or 1 to 5, wherein the OH group is bonded to a carbon atom.

[0088] Polyurethanes containing thiol functional groups can be derived from mixtures containing 15% by weight (such as 20% by weight or 25% by weight) to 30% by weight (such as 35% by weight or 40% by weight or 50% by weight or 60% by weight or 70% by weight) or any range (such as 15% by weight to 70% by weight, such as 20% by weight to 60% by weight, or 25% by weight to 50% by weight) of a compound containing thiol or mercapto groups, wherein the weight percentage is based on total resin solids.

[0089] C. Ionized polyurethane resin

[0090] When a polyurethane resin contains thiol functional groups and ionicly dispersible groups according to this disclosure, the polyurethane can be prepared by reacting an isocyanate reactive compound, such as a hydroxyl-functionalized polyester, polycarbonate, polyether, and / or acrylic polymer; or by reacting a polyhydroxy compound or polyhydroxycarboxylic acid with the polyisocyanate such that the ratio of NCO / isocyanate reactive groups is greater than 1:1, to generate an NCO-functionalized prepolymer. As a non-limiting example, acid groups can be introduced by using a polyhydroxycarboxylic acid, such as an acid-containing diol. The terminal isocyanate can then be reacted with a thiol-containing compound to produce a terminal SH-functionalized polymer. The acid-functionalized polyurethane polymer can be neutralized with a tertiary alkylated amine before and / or after contact with water to provide water dispersibility.

[0091] The polyurethane resins disclosed herein may include acidic polyols that react with polyisocyanates. Acidic polyols may include, but are not limited to, dimethylpropionic acid, 2,2-bis(hydroxymethyl)butyric acid, tartaric acid, 3,5-dihydroxybenzoic acid, ascorbic acid and its isomers, and any acid derivatives of the polyols described herein.

[0092] When ionic polyurethane resins include acid functionality, the acid value of the resin can be determined using a Metrohm 798 MPT Titrino automatic titrator manufactured by Metrohm AG according to ASTM D4662-15. This value is then divided by the total solids content to obtain the solids-based acid value. Resins containing active hydrogen can have solid-based acid values ​​greater than 8 mg KOH / g, greater than 25 mg KOH / g, greater than 50 mg KOH / g, greater than 60 mg KOH / g, greater than 70 mg KOH / g, greater than 75 mg KOH / g to greater than 80 mg KOH / g, greater than 85 mg KOH / g, greater than 90 mg KOH / g, greater than 100 mg KOH / g, or any range using any two of the foregoing values ​​as endpoints (such as 10 mg KOH / g to 100 mg KOH / g, 25 mg KOH / g to 90 mg KOH / g, 50 mg KOH / g to 85 mg KOH / g, or 60 mg KOH / g to 80 mg KOH / g).

[0093] Ionic polyurethane resins can be derived from mixtures containing 5% by weight (such as 10% or 15% by weight) to 20% by weight or 25% by weight or 30% by weight, or any range (such as 5% by weight or 30% by weight, or 10% by weight or 25% by weight or 15% by weight or 20% by weight) of an acidic polyol, wherein the weight percentage is based on the total resin solids.

[0094] When the dispersible groups of a polyurethane resin include ionic groups, the polyurethane resin may also include nonionic groups. When a polyurethane resin contains both ionic and nonionic groups, the ratio of ionic to nonionic groups may be 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:80.

[0095] D. Nonionic polyurethane resin

[0096] As a non-limiting example, polyurethane resins containing thiol functional groups and nonionic dispersible groups can be prepared by first reacting an isocyanate reactive compound (such as a hydroxyl functional compound) with a polyisocyanate such that the ratio of NCO / isocyanate reactive groups is greater than 1:1 to generate an NCO functional prepolymer. Then, the terminal isocyanate can be reacted with a polythiol or polythiol compound to produce a terminal SH functional polymer.

[0097] When the dispersible group includes a nonionic group, the dispersible group may include a polyoxyethylene group. The polyoxyethylene group may include poly(ethylene oxide), poly(propylene oxide), and / or copolymers of ethylene oxide and propylene oxide.

[0098] Suitable nonionic hydroxyl-functionalized compounds may include methoxy polyethylene glycol 350, 550 and / or 750, which are available from Dow (Midland, Michigan, USA). Suitable nonionic hydroxyl-functionalized compounds may also include methoxy polyethylene glycol 2000 and / or butoxypropylene glycol, which are available from Dow (Midland, Michigan, USA).

[0099] Nonionic polyurethane resins can be derived from mixtures containing 5 wt%, 10 wt%, 15 wt% to 20 wt%, 25 wt%, 30 wt%, 40 wt%, or any range (such as 5 wt% to 40 wt%, 5 wt% to 30 wt%, 10 wt% to 25 wt%, or 15 wt% to 20 wt%) of nonionic hydroxyl functional compounds, where wt% is based on total resin solids.

[0100] When the dispersible groups of a polyurethane resin include nonionic groups, it may also include ionic groups. When a polyurethane resin contains both nonionic and ionic groups, the ratio of nonionic to ionic groups can be 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:80.

[0101] Polyurethane resins can exist as aqueous dispersions in coating compositions.

[0102] E. Blends of ionic and nonionic polyurethane resins

[0103] The polyurethane resin in the coating compositions disclosed herein may include blends and / or combinations of ionic and nonionic polyurethane resins as described above. When using blends or other combinations, the ratio of ionic to nonionic polyurethane resin (defined by the ratio of ionic to nonionic groups) may be from 95:5 to 5:95, such as from 80:20 to 5:95, or from 60:40 to 10:90, or from 50:50 to 15:85, or from 65:35 to 20:80.

[0104] When the polyurethane resin comprises a blend of a polyurethane resin containing nonionic groups and a polyurethane resin containing ionic groups, the polyurethane resin may be used at a weight ratio of 1:20 to 20:1 (such as 1:4 to 20:1, 1:3 to 10:1, 1:2 to 10:1, or 1:2 to 8:1) of the polyurethane resin containing nonionic groups to the polyurethane resin containing ionic groups.

[0105] III. Crosslinking agent

[0106] The crosslinking agent includes functional groups that react with functional groups in the polyurethane resin. The crosslinking agent may include any of the crosslinking agents known in the art that react with the functionality of the resin used in the coating composition. The functional groups in the crosslinking agent may include, but are not limited to, epoxy, olefinic, and isocyanate functional groups. The crosslinking agent may react with thiol functional groups in the polyurethane resin.

[0107] A. Alkene crosslinking agent

[0108] When the functional group in the crosslinking agent includes an olefinic group, as a non-limiting example, the crosslinking agent may include (meth)acrylates containing molecules of two or more hydroxyl groups, (meth)acrylamides containing molecules of amines and two or more hydroxyl groups, allyl ethers containing molecules of two or more hydroxyl groups, (meth)acrylamide-functionalized addition polymers, polyurethanes, and polyesters.

[0109] When the crosslinking agent contains a thiol-reactive olefinic group, the crosslinking agent may include, but is not limited to, any compound containing two or more olefinic unsaturated groups, wherein the olefinic unsaturated groups have at least one electron-withdrawing functionality attached to a carbon atom of an unsaturated bond.

[0110] When the functional groups in the crosslinking agent include olefin groups, the molar ratio of thiol groups to olefin groups can be 1:3 to 3:1, such as 1:2 to 2:1 or 1:1.5 to 1.5:1.

[0111] The coating composition may contain 15 wt%, 30 wt%, 40 wt% to 50 wt%, 60 wt%, 70 wt%, or any range (such as 15 wt% to 70 wt%, 30 wt% to 60 wt%, or 40 wt% to 50 wt%) of an olefinic crosslinker, wherein the wt% is based on the total weight of the coating composition.

[0112] B. Epoxy crosslinking agent

[0113] The crosslinking agent may contain epoxy groups that react with functional groups in the polyurethane resin to form a crosslinked composition. Suitable epoxy-containing compounds may include, but are not limited to, compounds having two or more epoxy groups in the molecule, such as resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol, polyglycidyl ether, hydrogenated bisphenol A diglycidyl ether and its derivatives, bisphenol F diglycidyl ether and its derivatives, trimethylpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether, and polypropylene glycol diglycidyl ether.

[0114] Other compounds containing epoxy groups include, but are not limited to, epoxy-functionalized polymers, such as polymers derived from one or more olefinically unsaturated monomers containing epoxy groups, such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether.

[0115] The curable composition may include a molar ratio of thiol groups (such as those from polyurethane resins) to epoxy groups of 0.25:1.75, 0.5:1.5 to 0.75:1.25, 1:1, 0.75:1, 0.5:1 or any ratio within the foregoing range.

[0116] The coating composition may contain 15% by weight (such as 30% or 40% by weight) to 50% or 60% or 70% by weight, or any range (such as 15% to 70% by weight, 30% to 60% by weight, or 40% to 50% by weight) of epoxy crosslinker, or any range using any two of the foregoing values ​​as endpoints, wherein the weight percentage is based on the total weight of the coating composition.

[0117] C. Isocyanate crosslinking agent

[0118] Crosslinking agents may comprise isocyanates that react with functional groups in polyurethane resins to form crosslinked compositions. Non-limiting examples of suitable compounds containing isocyanate groups include isocyanates and blocked isocyanates. Suitable compounds having an effective number of isocyanate groups suitable for use as crosslinking agents in coating compositions include, but are not limited to, any isocyanate known from polyurethane chemistry, such as isocyanurate trimers of 1,6-diisocyanate, isocyanurate trimers of isophorone diisocyanate, urea diketone dimers of 1,6-diisocyanate, biuret of 1,6-diisocyanate, urethane carbamate of 1,6-diisocyanate, and mixtures thereof.

[0119] The curable composition may include a molar ratio of thiol groups (such as those from polyurethane resins) to isocyanate groups of a crosslinking agent of 0.25:1.75, 0.5:1.5 to 0.75:1.25, 1:1, 0.75:1, 0.5:1 or any ratio within the foregoing range.

[0120] The coating composition may contain 15% by weight (such as 30% or 40% by weight) to 50% or 60% or 70% by weight, or any range (such as 15% to 70% by weight, 30% to 60% by weight, or 40% to 50% by weight) of isocyanate crosslinking agent, or any range using any two of the foregoing values ​​as endpoints, wherein the weight percentage is based on the total weight of the coating composition.

[0121] IV. Alkaline catalyst

[0122] Any suitable basic catalyst may be used in the coating compositions disclosed herein. Suitable basic catalysts include, but are not limited to, primary, secondary, and / or tertiary amines, such as triethylamine and aldehyde imines.

[0123] When the basic catalyst includes an amine, the amine may include, but is not limited to, tertiary amines, tetramethylguanidine, 1,4-dihydropyrimidine, 1,8-diaza-bicyclo[5.4.0]undec-7-ene, 1,4-diaza-bicyclo[2.2.2]octane and 2-alkyl-N-alkylimidazoline.

[0124] The coating composition may include a catalyst in an amount of 0.1 wt% (such as 0.5 wt% or 1 wt%) to 5 wt%, 4.5 wt%, or 4 wt%, or in any range (such as 0.1 wt% to 5 wt%, 0.1 wt% to 4.5 wt%, or 0.5 wt% to 4 wt%) using any two of the foregoing values ​​as endpoints, wherein the wt% is based on the total weight of the coating composition.

[0125] V. Volatile acids

[0126] Any suitable volatile acid can be used in the coating composition. For environmentally curable coating compositions, the volatile acid can have a vapor pressure of at least 1 mm Hg (such as at least 1.5 mm Hg or at least 1.65 mm Hg) at 25°C, and at least the same vapor pressure at such temperatures when higher curing temperatures are used. Suitable volatile acids include, but are not limited to, those containing carboxylic acid groups, sulfonic acid groups, or aminosulfonic acid groups. When the volatile acid includes a carboxylic acid group, when using environmental curing temperatures, the volatile acid can include, but is not limited to, C1–C5 carboxylic acids, such as formic acid, acetic acid, propionic acid, lactic acid, isobutyric acid, etc. just Butyric acid and isovaleric acid. Volatile acids used for use at ambient curing temperatures are volatile at ambient temperatures and can function to control the curing rate at ambient temperatures.

[0127] When using higher curing temperatures, such as 40°C to 240°C, 45°C to 210°C, or 50°C to 140°C, acids that volatilize at those curing temperatures can be used. Non-limiting examples of acids that volatilize at higher curing temperatures and can be used include C2-C. 22 Straight-chain, branched, or cyclic aliphatic or aromatic carboxylic acids comprising 1 to 5, such as 1 to 4, or 1 to 3 carboxylic acid groups. Non-limiting examples of such acids include isononanoic acid and isostearic acid. Volatile acids used at higher curing temperatures may not be volatile at ambient temperature but are volatile at higher curing temperatures and can function to control the curing rate at those temperatures.

[0128] The coating composition may contain 0.01 wt% (such as 0.05 wt% or 0.1 wt%) to 0.5 wt% or 0.45 wt% or 0.4 wt% or any range (such as 0.01 wt% to 0.5 wt% or 0.01 wt% to 0.45 wt% or 0.05 wt% to 0.4 wt%) of volatile acid, or wt% based on the total weight of the coating composition.

[0129] VI. Other additives

[0130] This coating composition may contain conventional additives used in coating compositions in the art. Such additives include, but are not limited to, water, stabilizers, flow additives, fillers, plasticizers, antioxidants, hindered amine light stabilizers, UV absorbers and stabilizers, catalyst blockers, colorants (dyes, colored pigments, metallic pigments and / or pearlescent pigments), waxes, defoamers, surfactants, rheology modifiers, thixotropic agents, fillers, wetting agents, leveling agents, catalysts, abrasive carriers, and other conventional auxiliaries.

[0131] The coating composition can be aqueous or solvent-based. Solvent-based compositions may include any solvent known in the art, i.e., aliphatic and / or aromatic hydrocarbons. Examples include, but are not limited to, toluene, xylene, butyl acetate, ethyl acetate, acetone, methyl isobutyl ketone, methyl isopentyl ketone, methyl ethyl ketone, ether, ether alcohol, ether ester, hexanediol, butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, 1-butoxy-2-propanol, 1-isobutoxy-2-propanol, dipropylene glycol monomethyl ether; methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, ethylene glycol, diethylene glycol, dimethyl dipropylene glycol, diacetone alcohol, diacetone alcohol methyl ether, ethoxyethyl propionate, or any mixture of the above substances. Aqueous means that the composition contains a substantial proportion of water, such as at least 20% by weight, at least 30% by weight, or at least 40% by weight based on the total weight of the coating composition; however, it may also contain an organic co-solvent. The co-solvent used in the aqueous composition includes the same solvent as the organic solvents described above.

[0132] The coating compositions described herein may contain less than 780 g / L, such as less than 420 g / L or less than 250 g / L, based on the total composition, as determined by the following equation:

[0133]

[0134] Where C d Represents coating density, in pounds per gallon; W vm The percentage of the total weight of volatile substances to the total coating weight (lbs); W w This represents the percentage of water weight in the coating relative to the total weight (pounds) of the coating; and W e This represents the percentage of the weight of the exempted compound in the coating relative to the total weight (lbs) of the coating. Exempted compounds are defined by local regulations, if permitted. Examples of exempted solvents may include acetone, dimethyl carbonate, methyl acetate, p-chlorotrifluorotoluene (Oxsol 100), tert-butyl acetate, and propylene carbonate. The curable compositions disclosed herein may be completely VOC-free.

[0135] VII. Total Solids-Viscosity

[0136] The coating composition described herein may have at least 20% by weight (such as at least 21% by weight, at least 22% by weight, at least 23% by weight, at least 24% by weight, or at least 25% by weight) and at most 65% by weight (such as at most 50% by weight, at most 45% by weight, or at most 42% by weight); or 20% by weight to 65% by weight, such as 20% by weight to 50% by weight, at least 21% by weight, at least 45% by weight, at least 22% by weight, at least 42% by weight, or at least 25% by weight to 42% by weight of total resin solids.

[0137] The coating compositions described herein can have a viscosity of 10 to 500 cps (such as 20 to 100 cps), which is measured using a cone-plate viscometer, such as the CAP 2000 viscometer available from Brookfield (AMETEK Brookfield), at 25°C and 900 rpm using rotor #1.

[0138] The coating composition can be a one-component, two-component, or multi-component composition. When using a multi-component or two-component composition, one component may contain a polyurethane resin, and the other component may contain a crosslinking agent. Alkaline catalysts and volatile acids may be in any component or as individual components or multiple components.

[0139] The coating compositions described herein can be applied by forming a coating on at least a portion of a substrate, as a non-limiting example. The method may include: applying the coating composition to at least a portion of the substrate; and exposing the coating composition to a sufficient amount of energy for a sufficient duration to allow the coating composition to cure, such as through a reaction of a polyurethane resin with a crosslinking agent.

[0140] The coating composition can be applied using methods known in the art, such as spraying, scraping, brushing, dipping and / or precision application.

[0141] The aforementioned substrates may include iron, steel and aluminum, plastics, wood, composite materials, glass, synthetic materials, paper, leather and / or another coating.

[0142] The coating composition can be cured without restriction by exposure to environmental conditions, elevated temperatures, and / or photochemical radiation.

[0143] When the coating composition is cured by exposure to elevated temperatures, the temperatures can be 40°C to 240°C, 45°C to 210°C, or 50°C to 140°C.

[0144] Not bound by any particular theory, curing time can be affected by volatile acids. As a non-limiting example, volatile acids can inhibit the curing reaction in their presence, and their effect diminishes as the volatile acid evaporates. Coating compositions can have curing times ranging from 30 seconds to 24 hours, such as 1 minute to 12 hours, 5 minutes to 8 hours, 10 minutes to 4 hours, 30 seconds to 10 minutes, or 45 seconds to 5 minutes, as determined by achieving 100 MEK double rubs (MEKDR) with a rating of 8 or higher, as described below.

[0145] As noted above, the substrate may include a previously applied coating. As a non-limiting example, this coating composition may be part of a multilayer coating composition. As a non-limiting example, this coating composition may be a coating applied over a primer coating or a coating applied over a base coat.

[0146] Depending on the specific intended use, this coating composition can be applied as a top coat (such as a clear coat), or it can be applied as a direct gloss top coat or a single coat.

[0147] Applying this coating composition can produce a coating with a dry film thickness of 0.5 µm to 250 µm as measured according to ASTM D7091-21, such as 0.5 µm to 200 µm, 0.5 µm to 150 µm, 0.5 µm to 100 µm, 0.5 µm to 75 µm, 0.5 µm to 65 µm, 0.5 µm to 55 µm, 0.5 µm to 52 µm, 1 µm to 250 µm, 1 µm to 200 µm, 1 µm to 100 µm, 1 µm to 65 µm, 1 µm to 60 µm, 1 µm to 55 µm, 5 µm to 250 µm, 5 µm to 200 µm, 5 µm to 100 µm, 5 µm to 65 µm, 5 µm to 60 µm, or 5 µm to 55 µm.

[0148] This disclosure also provides a substrate at least partially coated with a coating formed from the above-described coating composition. Specifically, the coating composition can be applied to the substrate and cured to form a coating thereon. The coating can be a continuous film formed on at least a portion of the substrate.

[0149] The substrates to which the coating compositions can be applied include a variety of substrates. As a non-limiting example, the coating compositions disclosed herein can be applied to vehicle substrates, industrial substrates, aerospace substrates, and the like.

[0150] The vehicle substrate can include components of the vehicle. As a non-limiting example, the vehicle can include aviation substrates (components of aviation vehicles, such as aircraft, such as airplanes (e.g., private planes and small, medium, or large commercial passenger, cargo, and military aircraft), helicopters (e.g., private, commercial, and military helicopters), aviation vehicles (e.g., rockets and other spacecraft), etc.). Vehicles can also include land vehicles, such as animal trailers (e.g., horse-drawn carriages), all-terrain vehicles (ATVs), automobiles, trucks, buses, vans, heavy equipment, tractors, golf carts, motorcycles, bicycles, snowmobiles, trains, rail vehicles, etc. Vehicles can also include water vehicles, such as ships, small boats, hovercraft, etc. The vehicle substrate can include components of the vehicle's main body, such as the hood, doors, trunk, and roof of a car; the wings and fuselage of an aircraft or spacecraft; and the hull of a water vehicle.

[0151] The coating composition can be applied to industrial substrates, which may include, but are not limited to, tools, heavy equipment, furniture such as office furniture (e.g., office chairs, tables, filing cabinets, etc.), appliances such as refrigerators, ovens and stoves, dishwashers, microwave ovens, washing machines, dryers, small appliances (e.g., coffee makers, slow cookers, pressure cookers, blenders, etc.), metal hardware, extruded metals such as extruded aluminum for window frames, and other indoor and outdoor metal building materials.

[0152] This coating composition can be applied to storage tanks, windmills, nuclear plant components, packaging substrates, wood flooring and furniture, clothing, electronic equipment (including but not limited to housings and circuit boards), glass and transparent materials, sports equipment (including golf balls), stadiums, buildings, bridges, etc.

[0153] The substrate can be metallic or non-metallic. Metallic substrates include, but are not limited to, tin, steel (including electro-galvanized steel, cold-rolled steel, hot-dip galvanized steel, etc.), aluminum, aluminum alloys, zinc-aluminum alloys, steel coated with zinc-aluminum alloys, and aluminized steel. Non-metallic substrates include polymeric materials, plastics and / or composites, polyesters, polyolefins, polyamides, cellulose, polystyrene, polyacrylic acid, polyethylene naphthalate, polypropylene, polyethylene, nylon, ethylene vinyl alcohol (EVOH), polylactic acid, other “green” polymeric substrates, polyethylene terephthalate (“PET”), polycarbonate, polycarbonate propylene butadiene styrene (“PC / ABS”), wood, veneer, wood composites, particleboard, medium-density fiberboard, cement, stone, glass, paper, cardboard, textiles, synthetic and natural leather, etc. Substrates can include metals and / or plastics and / or composites and / or fibrous materials. Fiber materials can include nylon and / or thermoplastic polyolefin materials with continuous strands or short-cut carbon fibers. The substrate can be a substrate that has been treated in some way, such as to give visual and / or color effects, protective pretreatment, or other coatings.

[0154] The coating compositions disclosed herein may be particularly advantageous when applied to metal substrates. The coatings disclosed herein may be particularly advantageous when applied to metal substrates used in the manufacture of automotive vehicles such as cars, trucks, and tractors.

[0155] As a non-limiting example, a coating composition may be applied to a substrate having multiple parts, wherein the coating composition is applied to multiple parts simultaneously and cured simultaneously to form a coating on multiple parts without deforming, twisting, or otherwise degrading any part. A part may be a portion of a larger integral part of the substrate. Parts may be formed individually and subsequently arranged together to form the substrate. Parts may be integrally formed to form the substrate.

[0156] Non-limiting examples of components in the context of vehicle substrates include vehicle bodies (e.g., made of metal) and vehicle bumpers (e.g., made of plastic) that are formed separately and subsequently arranged to form the vehicle substrate. Other examples include plastic automotive parts, such as bumpers or trim strips, wherein the bumper or trim strip comprises areas or sub-components that contain more than one type of substrate. Further examples include aerospace or industrial parts that contain more than one type of substrate. It should be understood that other such multi-component substrates are contemplated within the context of this disclosure.

[0157] VIII. Properties of the Cured Composition

[0158] The coating compositions formed as described herein can exhibit solvent resistance and increased crosslinking density (XLD).

[0159] A. Solvent resistance test

[0160] To test the resistance of the coating composition, the solvent resistance of the substrate coated with the coating composition can be tested according to the following method.

[0161] Solvent resistance testing can be performed by placing the test panel on a flat table or other suitable flat, sturdy surface. A disposable wipe (such as WypAll L30) is folded into a square approximately one inch in size to test the solvent resistance of the cured panel.

[0162] The wiping cloth is saturated with a suitable solvent (such as methyl ethyl ketone (MEK)) for use on the test substrate. The wiping cloth is resaturated every 25 double rubs.

[0163] Immediately rub the substrate coated with the curable composition onto the test area using a saturated wiping cloth with back-and-forth motions of 2-4 inches.

[0164] You can continue to gently wipe back and forth, counting one "double rub" for each completed forward and backward movement, until the exposed substrate is exposed at the center of the rubbing strip, or until 100 double rubs are achieved.

[0165] Record the number of "double rubbing" cycles as the test result. The wiping cloth should be removed and replaced with a new one between each test sample.

[0166] The curable compositions formed using the methods described herein exhibit solvent resistance of at least 60 MEK double rubs (MEKDR), at least 70 MEK double rubs, at least 80 MEK double rubs, or at least 100 MEK double rubs, rated as level 8 or higher according to the following levels:

[0167]

[0168] B. Coating hardness

[0169] To test the hardness of a coating composition applied to a flat, rigid surface, a Koenig pendulum hardness test can be performed as detailed in ASTM D 4386-95. Coatings formed using the coating compositions described herein can have a Koenig hardness of at least 20 seconds (e.g., at least 25 seconds or at least 30 seconds).

[0170] aspect

[0171] A first aspect of this disclosure relates to a coating composition comprising: one or more polyurethane resins comprising thiol functional groups and dispersible groups; one or more crosslinking agents comprising functional groups that react with thiol functional groups; a basic catalyst; and a volatile acid.

[0172] A second aspect of this disclosure relates to a coating composition according to the first aspect, wherein the dispersible groups include ionic and nonionic groups.

[0173] A third aspect of this disclosure relates to a coating composition according to the second aspect, wherein the ratio of ionic groups to nonionic groups is 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:80.

[0174] The fourth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the polyurethane resin comprises a blend or combination of ionic and nonionic polyurethane resins, the blend or combination having a ratio of ionic to nonionic groups of 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:80.

[0175] The fifth aspect of this disclosure relates to a coating composition according to any of the preceding claims, wherein the dispersible groups include ionic groups.

[0176] The sixth aspect of this disclosure relates to a coating composition according to any of the foregoing aspects, wherein the dispersible groups include ionic groups, and the ionic groups include carboxylate groups.

[0177] The seventh aspect of this disclosure relates to a coating composition according to any of the foregoing aspects, wherein the dispersible groups include nonionic groups.

[0178] The eighth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the dispersible groups include polyoxyethylene groups.

[0179] The ninth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the dispersible groups comprise poly(ethylene oxide), poly(propylene oxide), and / or copolymers of ethylene oxide and propylene oxide.

[0180] The tenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the functional groups reacting with the thiol functional groups include olefinic groups, isocyanate groups, and / or epoxy groups.

[0181] The eleventh aspect of this disclosure relates to a coating composition according to the tenth aspect, wherein the ratio of thiol groups to olefinic groups is 1:3 to 3:1, such as 1:2 to 2:1 or 1:1.5 to 1.5:1.

[0182] The twelfth aspect of this disclosure relates to a coating composition according to any of the foregoing aspects, wherein the polyurethane resin is present in the coating composition as an aqueous dispersion.

[0183] The thirteenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the crosslinking agent comprises an acrylate containing two or more hydroxyl groups.

[0184] The fourteenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the basic catalyst comprises an amine, such as a tertiary amine.

[0185] The fifteenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the volatile acid comprises a carboxylic acid group, a sulfonic acid group, or an aminosulfonic acid group having a vapor pressure of at least 1 mm Hg, such as at least 1.5 mm Hg or at least 1.65 mm Hg, at 25°C or at a desired curing temperature.

[0186] The sixteenth aspect of this disclosure relates to a coating composition according to the fifteenth aspect, wherein the desired curing temperature is an ambient temperature, such as 23°C, and the volatile acid comprises C1–C5 carboxylic acids, such as formic acid, acetic acid, propionic acid, lactic acid, isobutyric acid, etc. just Butyric acid and / or isovaleric acid.

[0187] The seventeenth aspect of this disclosure relates to a coating composition according to the fifteenth aspect, wherein the curing temperature is 40°C to 240°C, such as 45°C to 210°C or 50°C to 140°C, and the volatile acid comprises a C2–C group containing 1 to 5, such as 1 to 4 or 1 to 3 carboxylic acid groups. 22 Straight-chain, branched, or cyclic aliphatic or aromatic carboxylic acids, such as isononanoic acid and isostearic acid.

[0188] The eighteenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the coating composition comprises at least 0.01 wt%, such as at least 0.05 wt%, or at least 0.1 wt%, and at most 0.5 wt%, such as at most 0.45 wt%, or at most 0.4 wt%, of the volatile acid, and may be from 0.01 wt% to 0.5 wt%, such as from 0.01 wt% to 0.45 wt%, or from 0.05 wt% to 0.4 wt%, of the amount of the volatile acid, wherein the wt% is based on the total weight of the coating composition.

[0189] The nineteenth aspect of this disclosure relates to a coating composition according to any of the preceding aspects, wherein the coating composition has at least 20 wt%, such as at least 21 wt%, or at least 22 wt%, or at least 23 wt%, or at least 24 wt%, or at least 25 wt%, and at most 65 wt%, such as at most 50 wt%, or at most 45 wt%, or at most 42 wt%, as determined according to ASTM D2369-20; or 20 wt% to 65 wt%, such as 20 wt% to 50 wt%, or 21 wt% to 45 wt%, or 22 wt% to 42 wt%, or 25 wt% to 42 wt%, of total resin solids.

[0190] The twentieth aspect of this disclosure relates to a coating composition according to any of the foregoing aspects, wherein the coating composition has a viscosity of 10 to 500 cps, such as 20 to 100 cps, as measured using a cone-plate viscometer at 25°C and 900 rpm.

[0191] The twenty-first aspect of this disclosure relates to a method of forming a coating on at least a portion of a substrate, the method comprising: applying a coating composition according to any of the preceding aspects onto at least a portion of the substrate; and exposing the coating composition to a sufficient amount of energy for a sufficient amount of time to allow the coating composition to cure.

[0192] The 22nd aspect of this disclosure relates to the method according to the 21st aspect, wherein the coating composition is applied using methods including spraying, scraping, brushing, dipping, and / or precision application.

[0193] The 23rd aspect of this disclosure relates to a method according to any one of the 21st or 22nd aspects, wherein the substrate includes iron, steel, aluminum, plastic, wood, composite materials, glass, synthetic materials, paper, leather and / or another coating.

[0194] The 24th aspect of this disclosure relates to a method according to any one of the 21st to 23rd aspects, wherein the coating composition is cured by exposure to environmental conditions, elevated temperature, and / or photochemical radiation.

[0195] The twenty-fifth aspect of this disclosure relates to the method according to the twenty-fourth aspect, wherein the coating composition is cured by exposure to elevated temperatures of 40°C to 240°C, 45°C to 210°C, or 50°C to 140°C.

[0196] The 26th aspect of this disclosure relates to a method according to any one of the 21st to 25th aspects, wherein the coating composition has a curing time of 30 seconds to 24 hours, such as 1 minute to 12 hours, 5 minutes to 8 hours, 10 minutes to 4 hours, 30 seconds to 10 minutes, or 45 seconds to 5 minutes at a curing temperature.

[0197] The 27th aspect of this disclosure relates to a method according to any one of the 21st to 26th aspects, wherein the coating composition has a curing time affected by the amount of acid and basic catalyst present in the coating composition.

[0198] The 28th aspect of this disclosure relates to a method according to any one of the 21st to 27th aspects, wherein the coating is applied over one or more previously applied coatings, and / or the coating is part of a multilayer coating composition.

[0199] The twentieth aspect of this disclosure relates to a method according to any one of the twenty-first to twenty-eighth aspects, wherein the coating is applied onto a base coat.

[0200] The thirtieth aspect of this disclosure relates to a method according to any one of the twenty-first to twenty-eighth aspects, wherein the coating is applied onto a primer coating.

[0201] The thirty-first aspect of this disclosure relates to a method according to any one of the twenty-first to twenty-eighth aspects, wherein the coating is a top coating, such as a transparent coating.

[0202] The thirty-second aspect of this disclosure relates to a method according to any one of the twenty-first to twenty-eighth aspects, wherein the coating is a single coating.

[0203] The thirty-third aspect of this disclosure relates to a method according to any one of the twenty-first to thirty-second aspects, wherein the coating has a dry film thickness of 0.5 µm to 250 µm, such as 0.5 µm to 200 µm, 0.5 µm to 150 µm, 0.5 µm to 100 µm, 0.5 µm to 75 µm, 0.5 µm to 65 µm, 0.5 µm to 55 µm, 0.5 µm to 52 µm, 1 µm to 250 µm, 1 µm to 200 µm, 1 µm to 100 µm, 1 µm to 65 µm, 1 µm to 60 µm, 1 µm to 55 µm, 5 µm to 250 µm, 5 µm to 200 µm, 5 µm to 100 µm, 5 µm to 65 µm, 5 µm to 60 µm, or 5 µm to 55 µm.

[0204] The thirty-fourth aspect of this disclosure relates to a substrate at least partially coated according to any one of the twenty-first to thirty-third aspects.

[0205] The thirty-fifth aspect of this disclosure relates to a substrate as described in the thirty-fourth aspect, wherein the substrate includes a vehicle substrate.

[0206] Example

[0207] The aspects of this disclosure are further illustrated by the following examples. It will be apparent to those skilled in the art that many modifications can be made to the materials and methods without departing from the scope of this disclosure.

[0208] Thiol equivalent weight

[0209] As used herein, “thiol equivalent weight” can be determined, and in the following example, as follows: A thiol-terminated polyurethane sample (0.2–0.6 g) is dissolved in 1 ml of pyridine and 30 ml of methyl ethyl ketone and toluene in a 1:1 weight ratio. The solution is titrated with 0.1 N iodine solution by colorimetric analysis until a persistent pale yellow color is observed in the solution. The thiol solid equivalent weight is calculated using the following equation.

[0210]

[0211] The reported thiol equivalent weight is the average of three repeated measurements.

[0212] Example 1 - Polyurethane Dispersion PUD-1

[0213] Table 1. Polyurethane dispersions (ionic dispersions; PUD-1)

[0214]

[0215] 1 Poly(tetrahydrofuran) polyols are available from BASF (Southfield, Michigan, USA).

[0216] 2 Dipropylene glycol dimethyl ether is available from Dow (Midland, Michigan, USA).

[0217] The contents of charge 1, as shown in Table 1, were added to a four-necked reaction flask equipped with a stirrer, gas inlet, thermometer, and condenser. After the exothermic reaction subsided, the temperature was raised to 80°C and maintained for 2 hours. Charge 2 was added, and the reaction was allowed to proceed exothermically. Once the exothermic reaction subsided, the reaction was maintained at 80°C until no NCO level was detected, as measured by infrared spectroscopy. Charge 3 was added. An aqueous dispersion was produced by dispersing 680 g of the resulting material into charge 4, which was heated to 60°C. The final dispersion had a measured solids content of 34.4% by weight, and the thiol equivalent weight was measured based on 714 g / mol iodine solids.

[0218] Example 2: Polyurethane dispersion – nonionic

[0219] Table 2 Polyurethane dispersions (nonionic dispersions; PUD-2)

[0220]

[0221] 3 Methoxylated polyethylene glycol 350 is available from Dow (Midland, Michigan, USA).

[0222] 4 Aliphatic polyisocyanate resins based on hexamethylene diisocyanate are available from Covestro (Pittsburgh, Pennsylvania, USA).

[0223] 5 Dipropylene glycol dimethyl ether is available from Dow (Midland, Michigan, USA).

[0224] Add the contents of charge 1 to a four-necked reaction flask equipped with a stirrer, gas inlet, thermometer, and condenser, as shown in Table 2. After the exothermic reaction subsides, raise the temperature to 80°C and maintain it for 2 hours. Add charge 2, then add charge 3. Allow the reaction to proceed exothermically. Once the exothermic reaction subsides, maintain the reaction at 80°C until no NCO level is detectable, as measured by infrared spectroscopy. The measured solids content of the solvent-based resin is 80.5% by weight, and the measured thiol equivalent weight based on solids is 441 g / mol iodine. An aqueous dispersion with a theoretical solids content of 40% by weight is produced by dispersing 200 g of material into charge 4.

[0225] Examples 3 to 5: Blends 1, 2 and 3

[0226] Blends of ionic and nonionic resin systems are shown in Table 3. Blends of PUD-1 and PUD-2 were prepared prior to coating formulation. The resins were added to 4-ounce glass jars in the amounts shown in Table 3. The blends were diluted to the desired solids level using deionized water. The mixture was stirred until homogeneous. An emulsion dispersion was obtained for each example.

[0227] Table 3

[0228]

[0229] Example 6

[0230] Thiol-acrylate coating formulations were prepared in 20 mL vials. Coatings were formulated using a 1:1 ratio of thiol equivalents to acrylate equivalents, as shown in Table 4. The order of addition for mixing is listed in the formulation information below. Each formulation was applied to ED7100 electrophoretic coated steel plates available from ACT Test Panel Technologies (273 Industrial Dr., Hillsdale, MI49242) using an 8-mil square bar. The panels were flash-cured at ambient conditions for 10 minutes, then cured in a 60°C oven for 45 minutes. The panels were then post-cured at ambient conditions for 24 hours, and MEK resistance and König hardness were then evaluated.

[0231] Table 4

[0232]

[0233] 6 Ethoxylated (3)-trimethylolpropane triacrylate, available from Sartomer (Exton, Pennsylvania, USA).

[0234] 7 A 10% by weight solution of 1,4-diazabicyclo[2.2.2]octane in deionized water.

[0235] 8 Silicone surfactants are available from BYK-Chemie GmbH (Wessel, Germany).

[0236] These examples demonstrate that, compared to pure ionomer systems, the use of nonionic resins allows for improved catalyst efficacy, increased curing performance, and enhanced hardness development, as evidenced by the higher König hardness and MEKDR ratings in Examples 6-1 to 6-4 compared to Example 6-5. The desired curing and viscosity balance was achieved by adjusting the ratio of nonionic to ionomer resins. Viscosities were determined using a CAP 2000 viscometer available from Brookfield (AMETEK Brookfield) at 25°C and 900 rpm using rotor #1.

[0237] Example 7

[0238] Thiol-epoxy coating formulations were prepared in 20 mL vials. Coatings were formulated using a 1:1 ratio of thiol equivalents to epoxy equivalents, as shown in Table 5. The order of addition of the mixtures is listed in the formulation information below. Each formulation was applied to ED7100 electrophoretic coated steel plates, available from ACT Test Panel Technologies (273 Industrial Dr., Hillsdale, MI 49242), using an 8-mil square bar. The panels were flash-cured at ambient conditions for 10 minutes, then placed in a 60°C oven for 45 minutes. The panels were then post-cured at ambient conditions for 24 hours, and MEK resistance and König hardness were then evaluated.

[0239] Table 5

[0240]

[0241] 7 A 10% by weight solution of 1,4-diazabicyclo[2.2.2]octane in deionized water.

[0242] 8 Silicone surfactants are available from BYK-Chemie GmbH (Wessel, Germany).

[0243] 9 Sorbitol polyglycidyl ether-based epoxy crosslinking agent is available from Nagase Specialty Materials N.A. LLC (Itasca, Illinois, USA).

[0244] Compared to pure ionomer resin systems, the use of nonionic resins allows for improved catalyst efficacy, increased curing performance, and enhanced hardness development, as demonstrated by the higher König hardness and MEKDR ratings in Examples 7-1 to 7-4 compared to Example 7-5. The introduction of nonionic resins also allows for improved viscosity relationships, with the viscosity of the blended PUD systems being lower than that of the nonionic-only system in Example 7-1, and the viscosity of the blends in Examples 7-2 to 7-4 being similar to or between the viscosity of Example 7-5 and that of Example 7-1. The desired curing and viscosity balance was achieved by adjusting the ratio of nonionic to ionomer resins. Viscosities were determined using a CAP 2000 viscometer available from Brookfield (AMETEK Brookfield) at 25°C and 900 rpm using rotor #1.

[0245] Example 8

[0246] These examples demonstrate the beneficial effects of using volatile acids to delay the curing response of the nonionic polyurethane and acrylate curing system in Example 2.

[0247] Table 6

[0248]

[0249] 7 A 10% by weight solution of 1,4-diazabicyclo[2.2.2]octane in deionized water.

[0250] 8 Silicone surfactants are available from BYK-Chemie GmbH (Wessel, Germany).

[0251] 10 Ethoxylated (3)-trimethylolpropane triacrylate, available from Sartomer (Exton, Pennsylvania, USA).

[0252] 11 The gel time was too short to measure the viscosity.

[0253] The examples shown in Table 6 were formulated with a 1:1 equivalent ratio of thiol to acrylate. The order of addition was: first the thiol-functionalized resin, then the triacrylate monomer and all other components except the initiator catalyst. The formulation was then stirred until a homogeneous, emulsion-like mixture was obtained. The catalyst was then added and stirred. The film was applied to an ED7100 electrophoretic coated steel plate, available from ACT Test Panel Technologies (273 Industrial Dr., Hillsdale, MI 49242), using an 8-mil square doctor blade. The film was then baked at 60°C for 45 minutes. After the panel was post-cured for one hour, MEK resistance and König hardness were tested.

[0254] The formulation and properties of the coatings are shown in Table 6. The uncatalyzed formulation (Example 8-1) showed a useful initial viscosity but did not exhibit any curing on the panel. Adding an amine catalyst (Example 8-2) induced curing, but it was too fast for reasonable application. Including volatile acids in a 1:1 molar ratio (Examples 8-3, 8-4, and 8-5) extended the gel time while still delivering curing on the panel. Viscosities were determined using a CAP 2000 viscometer available from Brookfield (AMETEK Brookfield) at 25°C and 900 rpm using rotor #1.

[0255] Example 9

[0256] These examples demonstrate the beneficial effects of using volatile acids to delay the curing response of the nonionic polyurethane and epoxy curing systems in Example 2.

[0257] As shown in Table 7, the examples were formulated with a 1:1 equivalent ratio of thiol to epoxy. The order of addition was to add the thiol-functionalized resin first, followed by the epoxy monomer. The formulation was then stirred until a homogeneous emulsion was obtained. The catalyst was then added and stirred. The film was applied to an ED7100 electrophoretic coated steel plate, available from ACT Test Panel Technologies (273 Industrial Dr., Hillsdale, MI 49242), using an 8-mil square doctor blade. The film was then baked at 60°C for 45 minutes. After the panel was post-cured for one hour, MEK resistance and König hardness were tested.

[0258] As shown in Table 7, the uncatalyzed formulation (Example 9-1) showed a useful initial viscosity relationship but did not exhibit any curing on the panel. Adding an amine catalyst (Example 9-2) induced curing, but this was too rapid for reasonable application, resulting in a short gel time of 10 minutes. Including volatile acids in a 1:1 molar ratio (Examples 9-3, 9-4, and 9-5) extended the gel time while still delivering curing on the panel. Viscosities were determined using a CAP2000 viscometer, available from Brookfield (AMETEK Brookfield), at 25°C and 900 rpm using rotor #1.

[0259] Although specific embodiments of this disclosure have been described above for illustrative purposes, it will be apparent to those skilled in the art that various modifications may be made to the details of this disclosure without departing from the scope defined in the appended claims.

[0260] Table 7

[0261]

[0262] 7 A 10% by weight solution of 1,4-diazabicyclo[2.2.2]octane in deionized water.

[0263] 8 Silicone surfactants are available from BYK-Chemie GmbH (Wessel, Germany).

[0264] 12 Sorbitol polyglycidyl ether-based epoxy crosslinking agent is available from Nagase Specialty Materials N.A. LLC (Itasca, Illinois, USA).

Claims

1. A coating composition comprising: One or more polyurethane resins, wherein the polyurethane resins comprise thiol functional groups and dispersible groups; One or more crosslinking agents, said crosslinking agent comprising functional groups that react with said thiol functional groups; Alkaline catalysts; and Volatile acid.

2. The coating composition according to claim 1, wherein the dispersible groups of the polyurethane resin comprise ionic groups and / or nonionic groups, such that when ionic and nonionic groups are present, they are present in a ratio of ionic to nonionic groups of 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:

80.

3. The coating composition according to any of the preceding claims, wherein the polyurethane resin comprises a blend or combination of ionic and nonionic polyurethane resins, the blend or combination having a ratio of ionic to nonionic groups of 80:20 to 5:95, such as 60:40 to 10:90, 50:50 to 15:85, or 65:35 to 20:

80.

4. The coating composition according to any of the preceding claims, wherein the dispersible group comprises an ionic group containing a carboxyl group, and / or the dispersible group comprises a polyoxyethylene group, such as poly(ethylene oxide), poly(propylene oxide), and / or a copolymer of ethylene oxide and propylene oxide.

5. The coating composition according to any of the preceding claims, wherein the functional group reacting with the thiol functional group comprises an olefinic group, an isocyanate group, and / or an epoxy group, wherein the ratio of the thiol group to the functional group reacting with the thiol functional group is 1:3 to 3:1, such as 1:2 to 2:1 or 1:1.5 to 1.5:

1.

6. The coating composition according to any of the preceding claims, wherein the crosslinking agent comprises an acrylate containing two or more hydroxyl groups.

7. The coating composition according to any of the preceding claims, wherein the alkaline catalyst comprises an amine, such as a tertiary amine.

8. The coating composition according to any of the preceding claims, wherein the volatile acid comprises a carboxylic acid group, a sulfonic acid group, or an aminosulfonic acid group having a vapor pressure of at least 1 mm Hg, such as at least 1.5 mm Hg or at least 1.65 mm Hg, at 25°C or at the desired curing temperature.

9. The coating composition of claim 15, wherein the desired curing temperature is an ambient temperature, such as 23°C, and the volatile acid comprises C1–C5 carboxylic acids, such as formic acid, acetic acid, propionic acid, lactic acid, isobutyric acid, etc. just Butyric acid and / or isovaleric acid; or The desired curing temperature is 40°C to 240°C, such as 45°C to 210°C or 50°C to 140°C, and the volatile acid comprises C2–C groups including 1 to 5, such as 1 to 4 or 1 to 3 carboxylic acid groups. 22 Straight-chain, branched, or cyclic aliphatic or aromatic carboxylic acids, such as isononanoic acid and isostearic acid.

10. The coating composition according to any preceding claim, wherein the coating composition comprises at least 0.01 wt%, such as at least 0.05 wt% or at least 0.1 wt% and at most 0.5 wt%, such as at most 0.45 wt% or at most 0.4 wt%, and may be from 0.01 wt% to 0.5 wt%, such as 0.01 wt% to 0.45 wt% or 0.05 wt% to 0.4 wt%, of the volatile acid, wherein the wt% is based on the total weight of the coating composition; and / or The coating composition thereof has at least 20% by weight, such as at least 21% by weight, or at least 22% by weight, or at least 23% by weight, or at least 24% by weight, or at least 25% by weight, and at most 65% by weight, such as at most 50% by weight, or at most 45% by weight, or at most 42% by weight, as determined according to ASTM D2369-20; or 20% by weight to 65% by weight, such as 20% by weight to 50% by weight, or 21% by weight to 45% by weight, or 22% by weight to 42% by weight, or 25% by weight to 42% by weight, of total resin solids.

11. A method of forming a coating on at least a portion of a substrate, the method comprising: The coating composition according to any of the preceding claims is applied to at least a portion of the substrate; as well as Expose the coating composition to a sufficient amount of energy for a sufficient amount of time to allow the coating composition to cure; The coating composition is applied using methods including spraying, scraping, brushing, dipping, and / or precision coating; and The substrates include iron, steel, aluminum, plastic, wood, composite materials, glass, synthetic materials, paper, leather and / or another coating.

12. The method of claim 11, wherein the coating composition is cured by exposure to environmental conditions, elevated temperature, and / or photochemical radiation; The coating composition is cured by exposure to elevated temperatures of 40°C to 240°C, 45°C to 210°C, or 50°C to 140°C; and / or The coating composition has a curing time of 30 seconds to 24 hours, such as 1 minute to 12 hours, 5 minutes to 8 hours, 10 minutes to 4 hours, 30 seconds to 10 minutes, or 45 seconds to 5 minutes at the curing temperature.

13. The method according to claim 11 or 12, wherein the coating composition has a curing time affected by the amount of acid and basic catalyst present in the coating composition.

14. The method according to any one of claims 11 to 13, wherein the coating is applied over one or more previously applied coatings, and / or is part of a multilayer coating composition; The coating is applied onto the base coat; or The coating is applied over a primer coating; or The coating mentioned above is a top coating, such as a transparent coating.

15. The method according to any one of claims 11 to 13, wherein the coating is a single coating.

16. The method according to any one of claims 11 to 15, wherein the coating has a dry film thickness of 0.5 µm to 250 µm, such as 0.5 µm to 200 µm, 0.5 µm to 150 µm, 0.5 µm to 100 µm, 0.5 µm to 75 µm, 0.5 µm to 65 µm, 0.5 µm to 55 µm, 0.5 µm to 52 µm, 1 µm to 250 µm, 1 µm to 200 µm, 1 µm to 100 µm, 1 µm to 65 µm, 1 µm to 60 µm, 1 µm to 55 µm, 5 µm to 250 µm, 5 µm to 200 µm, 5 µm to 100 µm, 5 µm to 65 µm, 5 µm to 60 µm, or 5 µm to 55 µm.

17. A substrate, which is at least partially coated according to the method of any one of claims 11 to 16.

18. The substrate of claim 17, wherein the substrate comprises a vehicle substrate.

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