Aqueous dispersion of a crosslinking component for cationic paint binders

Abstract

The present invention relates to an aq. dispersion (XD) of a crosslinking component (X) for cationic amino-containing resins which contain -OH groups and / or primary or secondary amine groups, (X) being an amine-containing blocked polyisocyanate and the reaction product of a mixture comprising at least one polyisocyanate comprising more than 2 isocyanate groups per molecule; at least one polyol comprising at least three -OH groups per molecule, wherein two of the -OH groups are more reactive towards isocyanate than the other one(s); at least one amine comprising at least one tertiary amine group and additionally at least two groups being reactive towards isocyanate; at least one blocking agent; and at least one neutralizing acid; the at least one amine having at least one tertiary amine group which is laterally pending from the backbone of (X), and the nitrogen atom of the at least one laterally pending tertiary amine group being separated from the backbone of (X) by at least one intervening atom. It also relates to a method for making (XD) and to the use thereof for coating a substrate by cathodic electrodeposition, a coating bath for cathodic electrodeposition, a water-dilutable paint, a method for making the paint as well as to the use thereof.

Description

[0001] AQUEOUS DISPERSION OF A CROSSLINKING COMPONENT FOR CATIONIC PAINT BINDERS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an aqueous dispersion of a crosslinking component for cationic amino-containing resins as well as to a water-dilutable paint for cathodically depositable electrodip coatings comprising said aqueous dispersion. The present invention further relates to a coating bath for cathodic electrodeposition comprising said aqueous dispersion. The present invention further relates to a process for making the aqueous dispersion, a process for making the water-dilutable paint, as well as a use of the aqueous dispersion or of the water-dilutable paint for coating a substrate by cathodic electrodeposition.

[0004] BACKGROUND OF THE INVENTION

[0005] Cationic electrodeposition (CED) paints (also known as e-coats) are widely used for coating car bodies due to their excellent corrosion resistance and uniform coverage. Typically these paints comprise of a film-forming binder resin (e.g. a cationic epoxy-amine-adduct) and a thermal crosslinker (e.g. a blocked polyisocyanate). A key element in the formulation of CED paints is the crosslinker, which facilitates the curing process to form a robust and resilient film. Blocked polyisocyanate crosslinkers are commonly employed due to their stability at room temperature and reactivity upon heating. This thermal activation allows for controlled curing, which is essential for achieving desired coating properties. Often the crosslinker alone is not dispersible in water, but rather co-dispersed together with the neutralized cationic binder resin to form micelles that comprise both, the binder resin and the crosslinker. These aqueous dispersions have a fixed ratio between binder resin and crosslinker which can not be easily adapted by the paint producer. There is a desire in the art to have crosslinkers for CED paints available which are in the form of aqueous dispersions and which can easily be mixed with the cationic film forming binder in any ratio by the paint producer. US Patent Number 5,977,247 relates to curing agents, for aqueous coating compositions, which are present as solvent-free aqueous dispersions and whose properties are at least equal to those of the conventional solvent-containing systems. Furthermore, in efforts to also enhance energy efficiency and reduce processing times, there is an ongoing industry-wide push towards coatings that cure at lower temperatures without compromising performance. Achieving low-temperature curing, or low bake performance, typically involves the use of specific blocking agents that can unblock at reduced temperatures. Traditional blocking agents such as methyl ethyl ketoxime (MEKO) and pyrazoles have been utilized for this purpose in many coating formulations.

[0006] W02023 / 078670 A1 relates to self-emulsifying blocked polyisocyanate dispersions that are able to perform curing at a lower temperature, which have a good storage stability and from which the obtained coating films show satisfying performance. The blocking agent for the isocyanate is particularly selected from oximes, pyrazoles and active methylene compounds.

[0007] However, reliance on these traditional blocking agents presents several challenges. Some of these agents are e.g. associated with regulatory and environmental concerns, leading to increased scrutiny and potential restrictions on their use. Additionally, they may impart unwanted characteristics to the coatings, such as discoloration or odor, and could affect the overall hydrolytic stability and shelf life of the coating formulations. Another consideration in the development of aqueous CED paints is the storage stability (in particular the colloidal stability) of the crosslinker dispersions. Stability is crucial to ensure consistent application properties and performance over the product's lifespan.

[0008] EP1956056 A2 relates to cathodic electrodeposition coating compositions that can be bake cured at low temperatures. Undesired pressure build-up within the containers due to decomposition of the polyisocyanate on storage is prevented by the presence of at least one polybasic acid in a proportion of 1 to 50 meq (milliequivalents) acid per 100 g of resin solids. While effective in maintaining dispersion stability, the inclusion of such acids can introduce formulation complexities and may influence the curing behavior and final properties of the coatings.

[0009] Given the above-mentioned challenges, there is still a continuing need for advancements in the field of cathodic electrodeposition paints. Such developments would enhance formulation flexibility, regulatory compliance, and overall performance of CED coatings in various applications.

[0010] AIM OF THE INVENTION

[0011] It is therefore an object of embodiments of the present invention to provide aqueous dispersions of a blocked isocyanate hardener that address low-temperature curing without dependence on harmful blocking agents, as well as improvements in storage stability without additional stabilizing components, and that have a low content of volatile organic compound (VOC). The aqueous dispersions should preferably further have a high solids content, a low particle size as well as a low amount of acid equivalents (MEQ acid value).

[0012] SUMMARY OF THE INVENTION

[0013] In a first aspect, the present invention relates to an aqueous dispersion of a crosslinking component for cationic amino-containing resins which contain hydroxyl groups and / or primary or secondary amine groups, the crosslinking component being an amine-containing blocked polyisocyanate and the reaction product of a reaction mixture comprising:

[0014] a) at least one polyisocyanate comprising more than 2 isocyanate groups per molecule,

[0015] b) at least one polyol comprising at least three hydroxyl groups per molecule, wherein two of the hydroxyl groups are more reactive towards isocyanate than the other one(s),

[0016] c) at least one amine comprising at least one tertiary amine group and additionally at least two groups being reactive towards isocyanate,

[0017] d) at least one blocking agent,

[0018] e) at least one neutralizing acid, and

[0019] f) optionally an organic co-solvent;

[0020] the at least one amine having at least one tertiary amine group which is laterally pending from the backbone of the crosslinking component and the nitrogen atom of the at least one laterally pending tertiary amine group being separated from the backbone by at least one intervening atom.

[0021] This allows the crosslinking component to provide low bake performance without using classical low bake blocking agents while maintaining storage stability without polybasic acids.

[0022] In a second aspect, the invention relates to a water-dilutable paint for cathodically depositable electrodip coatings comprising:

[0023] a) a cationic amino-containing resin with OH and / or primary or secondary amine groups;

[0024] b) the aqueous dispersion of a crosslinking component of the first aspect; c) optionally, a curing catalyst. The aqueous crosslinker dispersion provides low bake performance to the cathodic electrocoat paint.

[0025] In a third aspect, the invention relates in one embodiment to a process for making the aqueous dispersion of the first aspect, comprising:

[0026] a) providing a mixture of the polyol, blocking agent, and optional co-solvent at 50-150°C;

[0027] b) adding the polyisocyanate, preferably over 0.5-10.0 hrs;

[0028] c) adding the amine, preferably over a period of less than 5.0 hrs;

[0029] d) adding the neutralizing acid, preferably diluted in 20-80% water; and e) adding water and stirring to form the aqueous dispersion.

[0030] This provides a controlled way to make the aqueous crosslinker dispersion.

[0031] In another embodiment of the third aspect, the invention relates to a process for making the aqueous dispersion of the first aspect, comprising:

[0032] a-1 ) providing a mixture of the at least one polyol, the at least one blocking agent, the amine(s), and optional co-solvent at 30-150°C;

[0033] b-1) adding the polyisocyanate, preferably over 0.5-10.0 hrs;

[0034] c-1) adding the neutralizing acid, preferably diluted in 20-80% water; and d-1) adding water and stirring to form the aqueous dispersion.

[0035] This provides an efficient way to make the aqueous crosslinker dispersion.

[0036] In a fourth aspect, the invention relates to a process for making the cathodic electrocoat paint of the second aspect by mixing:

[0037] - the cationic amino epoxy resin,

[0038] - the aqueous crosslinker dispersion, and

[0039] - optionally a curing catalyst.

[0040] In a fifth aspect, the invention relates to a cathodic electrodeposition bath comprising the aqueous crosslinker dispersion of the first or third aspect. This bath enables low bake electrocoating.

[0041] In a sixth aspect, the invention relates to using the aqueous crosslinker dispersion of the first or third aspect, or using the cathodic electrocoat paint of the second or fourth aspect, for cathodically electrocoating a substrate. This provides coatings with low bake performance.

[0042] It is an advantage of embodiments of the present invention that

[0043] - low bake performance is achieved without the use of classical low bake blocking agents such as MEKO or pyrazoles. - storage stability is maintained without the need for polybasic acids.

[0044] - stable dispersions with high solids content, low MEQ acid values, and low particle sizes can be obtained.

[0045] - low bake performance is achieved with non-classical blocking agents, potentially reducing regulatory concerns associated with traditional agents. - the aqueous dispersion allows for low volatile organic compound formulations and enhanced storage stability.

[0046] - low cure temperature coatings are possible, leading to energy savings and reduced processing times.

[0047] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying examples illustrating the principles of the invention.

[0048] DETAILED DESCRIPTION OF THE INVENTION

[0049] The following terms are provided to aid in the understanding of the invention.

[0050] As used herein, the wording "more reactive towards isocyanate than the other one(s)" refers to hydroxyl groups in the polyol that have a higher reactivity with isocyanate groups, such that they react more readily or at a faster rate under identical reaction conditions. Examples of more reactive hydroxyl groups include primary hydroxyl groups compared to secondary or tertiary hydroxyl groups.

[0051] As used herein, the term “aqueous dispersion” refers to a liquid system where very small polymer particles or droplets (the dispersed phase), preferably particles or droplets having an average particle size (determined according to DIN ISO 13321) of below 200 nm, are uniformly dispersed in water (the continuous phase). These particles or droplets are typically water-insoluble and are stabilized (typically by electrostatic repulsion) within the water phase to prevent them from clumping or coalescing together. The continuous phase predominantly comprises water, however, organic co-solvents can optionally be present.

[0052] As used herein, the wording "groups being reactive towards isocyanate" refers to functional groups capable of reacting with isocyanate groups to form covalent bonds. Such groups include, but are not limited to, hydroxyl groups, primary amine groups, secondary amine groups and mercaptan groups. As used herein, the term "blocking agent" refers to a compound that reacts with isocyanate groups to form a blocked isocyanate, which prevents premature reaction but can regenerate the free isocyanate group under specific conditions such as heat. Examples of blocking agents include (but are not limited to) oximes, pyrazoles, active methylene compounds, aliphatic alcohols, cycloaliphatic alcohols, aromatic alcohols, glycol ethers, lactams, mercaptans, imidazoles, triazoles, amines, imines, hydroxylamines, hydroxyalkyl esters, and mixtures thereof.

[0053] As used herein, the term "neutralizing acid" refers to an acid used to neutralize basic groups in the resin or dispersion, to form cationic salt groups and to enhance water dispersibility of the resin. Examples of neutralizing acids include (but are not limited to) formic acid, acetic acid, propanoic acid, lactic acid, oxalic acid, glycolic acid, citric acid, malic acid, adipic acid, succinic acid, fumaric acid, benzoic acid, methansulphonic acid and any combinations thereof.

[0054] As used herein, the term "non-volatile content" refers to the percentage by weight of the aqueous dispersion that remains after the removal of all volatile components under specified conditions. It is determined by weighing a sample of the aqueous dispersion followed by drying the sample of the dispersion at a defined temperature and time, such as heating at 125°C for one hour, weighing the residue of solid or liquid material after drying, and calculating the weight percentage of the residue by dividing the weight of the residue by the weight of the original sample. For example, a non-volatile content of 25.0 to 55.0% means that after drying, this percentage of the original sample weight remains as solid or liquid material.

[0055] As used herein, the wording "and mixtures thereof" indicates that the components listed may be used individually or in any combination. For instance, when referring to blocking agents selected from a specific group "and mixtures thereof," it means that the blocking agent can be any one of the listed compounds or any combination of two or more of them.

[0056] In the first aspect, the present invention relates to an aqueous dispersion (XD) of a crosslinking component (X) for cationic amino-containing resins which contain hydroxyl groups and / or primary or secondary amine groups, wherein the crosslinking component (X) is an amine-containing blocked polyisocyanate. Specifically, the crosslinking component (X) is the reaction product of a reaction mixture comprising (or, in other words, the crosslinking component (X) is obtainable by reacting the following reactants):

[0057] a) at least one polyisocyanate (I) comprising (on average) more than two isocyanate groups per (polyisocyanate) molecule (or, comprising (on average) more than two isocyanate groups in one (polyisocyanate) molecule),

[0058] b) at least one polyol (PO) comprising at least three hydroxyl groups per (polyol) molecule, wherein two of the hydroxyl groups are more reactive towards isocyanate than the other one(s),

[0059] c) at least one amine (A) comprising at least one tertiary amine group and additionally at least two, preferably two groups being reactive towards isocyanate,

[0060] d) at least one blocking agent (BA),

[0061] e) at least one neutralizing acid (NA), and

[0062] f) optionally an organic co-solvent (S);

[0063] with the at least one amine (A) having at least one tertiary amine group which is laterally pending from the backbone of the crosslinking component (X), and the nitrogen atom of the at least one laterally pending tertiary amine group being separated from the backbone by at least one, preferably by one to six, more preferably by one to four, intervening atom(s), preferably (the intervening atom(s) being (a)) carbon atom(s). This composition of reaction mixture allows the obtained crosslinking component (X) to provide low bake performance without using classical low bake blocking agents (such as MEKO or pyrazoles) while maintaining storage stability without the need for polybasic acids.

[0064] Throughout the present specification, “aqueous dispersion (XD) of a crosslinking component (X)” is also referred to as “aqueous crosslinker dispersion” or “crosslinker dispersion”.

[0065] As used herein, the term "reaction product" refers to the chemical compound or mixture resulting from the chemical reaction of the specified reactants under given conditions, particularly, the chemical reaction between isocyanate groups and groups being reactive towards isocyanate. The reaction product encompasses all possible products formed from the reactants, including the desired products and any by-products.

[0066] The crosslinking component (X) is the amine-containing blocked polyisocyanate formed from the reaction mixture comprising (or obtained by reacting) the polyisocyanate(s) (I) with more than two isocyanate groups per molecule, the polyol(s) (PO) with at least three hydroxyl groups per molecule where two of the hydroxyl groups are more reactive towards isocyanate than the other(s), the amine(s) (A) with at least one tertiary amine group and at least two groups reactive towards isocyanate, the blocking agent(s) (BA), the neutralizing acid(s) (NA), and optionally the organic cosolvents) (S). The at least one amine (A) introduces tertiary amine groups that are laterally pending from the backbone of the crosslinking component (X), the nitrogen atom comprised in the laterally pending tertiary amine group is separated from the backbone by at least one intervening atom, which is critical for providing the desired properties.

[0067] As used herein, the term “on average” refers to the average number of isocyanate groups per (polyisocyanate) molecule, in other words, the molar amount of isocyanate groups divided by the molar amount of the polyisocyanate molecules.

[0068] As used herein, the wording "separated from the backbone of the crosslinking component (X) by at least one intervening atom" means that the nitrogen atom comprised in the tertiary amine group (or, the nitrogen atom of the tertiary amine group) is attached to the main chain of the crosslinking component through at least one atom, said one atom serving as a spacer (referred to as spacer atom). This spacer atom prevents the nitrogen atom comprised in the tertiary amine group from being directly bonded to the backbone, allowing for improved flexibility and reactivity. An example of an intervening atom is the carbon atom of a methylene (-CH2-) group.

[0069] Preferably, the at least one polyisocyanate (I) does (on average) not comprise 2 or less isocyanate groups per molecule. More preferably, the at least one polyisocyanate (I) comprises (on average) between 2 and 4, even more preferably between 2.1 and 3.5 isocyanate groups per molecule.

[0070] The difference in reactivity towards isocyanate of the hydroxyl groups comprised in the at least one polyol (PO) can have several reasons of which the skilled person is well aware, for example the reactivity of a primary hydroxyl group is higher than the reactivity of a secondary hydroxyl group, and the reactivity of a secondary hydroxyl group is higher than the reactivity of a tertiary hydroxyl group. Preferably, the polyol (PO) comprises at least three hydroxyl groups per molecule, wherein two of the hydroxyl groups are primary hydroxyl groups and the at least one remaining hydroxyl group(s) is (are) secondary or tertiary hydroxyl group(s). More preferably, the polyol (PO) comprises three hydroxyl groups per molecule, wherein two of the hydroxyl groups are primary hydroxyl groups and one hydroxyl group is a secondary or tertiary hydroxyl group, even more preferably the polyol (PO) is selected from the list consisting of glycerol, 1 ,2,6-hexantriol, and mixtures thereof.

[0071] In a preferred embodiment, the polyol (PO) is the reaction product of a cyclic alkylene carbonate (CAC) with an alkanolamine (AA), which is a convenient way to synthesize the polyol component with the desired hydroxyl functionalities. As used herein, the wording "the reaction product of a cyclic alkylene carbonate (CAC) with an alkanolamine (AA)" refers to a polyol obtained by reacting a cyclic alkylene carbonate compound, such as propylene carbonate, with an alkanolamine, such as diethanolamine. This reaction yields a polyol with multiple hydroxyl groups suitable for use in the dispersion. Preferably, the cyclic alkylene carbonate (CAC) is a cyclic C2-C8-alkylene carbonate, more preferably a cyclic C3-C8-alkylene carbonate, most preferably propylene carbonate. Preferably, the alkanolamine (AA) is a dialkanolamine, more preferably a dialkanolamine comprising two primary hydroxyl groups, most preferably diethanolamine, dipropanolamine, or mixtures thereof. In a most preferred embodiment, the polyol (PO) is the reaction product of propylene carbonate and diethanolamine.

[0072] Without being bound by theory, it is believed that the use of the polyol (PO) in combination with the polyisocyanate (I) as in the present invention is essential to create a crosslinking component (X) with a sufficient amount of isocyanate end groups and a balanced degree of branching without running into issues with high viscosity or gelling during the synthesis of (X).

[0073] In embodiments of the present invention, the reaction mixture (for obtaining crosslinking component (X)) comprises:

[0074] a) 20-80 % by weight, preferably 25-70 % by weight, more preferably 30-60 % by weight, of the at least one polyisocyanate (I), b) 1-30 % by weight, preferably 1-20 % by weight, more preferably 2-15 % by weight, of the at least one polyol (PO),

[0075] c) 1-15 % by weight, preferably 2-13 % by weight, more preferably 3-12 % by weight, of the at least one amine (A),

[0076] d) 10-50 % by weight, preferably 15-45 % by weight, more preferably 20-40 % by weight, of the at least one blocking agent (BA),

[0077] e) 0.5-8 % by weight, preferably 1-6 % by weight, more preferably 1-4 % by weight, of the at least one neutralizing acid (NA), and

[0078] f) 0-20 % by weight, preferably 0-15 % by weight, more preferably 0-10 % by weight, of the optional organic co-solvent (S);

[0079] where the sum of components (I), (PO), (A), (BA), (NA), and (S) equals to 100 % by weight. This reaction mixture provides an optimal composition for the crosslinking component (X).

[0080] In another, alternative, embodiment, the reaction mixture (for obtaining crosslinking component (X)) comprises:

[0081] a) 20-80 % by weight, preferably 25-70 % by weight, more preferably 30-60 % by weight, of the polyisocyanate (I),

[0082] b) 1-30 % by weight, preferably 1-20 % by weight, more preferably 2-15 % by weight, of the polyol (PO),

[0083] c) 1-15 % by weight, preferably 2-13 % by weight, more preferably 3-12 % by weight, of the amine (A),

[0084] d) 10-50 % by weight, preferably 15-45 % by weight, more preferably 20-40 % by weight, of the blocking agent (BA),

[0085] e) 0.5-8 % by weight, preferably 1-6 % by weight, more preferably 1-4 % by weight, of the neutralizing acid (NA), and

[0086] f) 0.5-20 % by weight, preferably 1-15, more preferably 2-10 % by weight, of the organic co-solvent (S);

[0087] where the sum of components (I), (PO), (A), (BA), (NA), and (S) equals 100 % by weight. The crosslinking component (X) of the present invention may only comprise the minimum necessary amount of organic co-solvent (S) in order to manage the viscosity of the crosslinking component (X) during synthesis and facilitate the dispersion in water on the one hand, and on the other hand keep the content of volatile organic compound (VOC) of the aqueous dispersion (XD) at a low level. Finding thereto the suitable amount of organic co-solvent (S) (still within the ranges given in the above embodiments), for use in the reaction mixture for obtaining crosslinking component (X), is well within the practice of those skilled in the art. It is an advantage of embodiments of the present invention that the aqueous dispersion (XD) allows for low volatile organic compound formulations having enhanced storage stability.

[0088] Preferably, the organic co-solvent (S) is an inert solvent. As used herein, the term “inert solvent” refers to an organic solvent that does not comprise groups being reactive towards isocyanate. Suitable organic co-solvents (S) may be acetone, butanone, methyl isobutyl ketone (MIBK), cyclohexanone, N-methyl-2-pyrrolidone (NMP), acetonitrile, dimethyl sulfoxide (DMSO), tetrahydrofurane (THF), 1,4-dioxane, C1-C4-alkyl-C1-C4-alkanoates, bis(2-(2-butoxyethoxy)ethoxy)methane (butylcarbitol formal), and any combinations thereof. More preferably, the organic co-solvent (S) is an inert solvent and has at a temperature of 293.15 K a vapour pressure of less than 0.01 kPa. Most preferably, the organic co-solvent (S) is bis(2-(2-butoxyethoxy)ethoxy)methane (butylcarbitol formal).

[0089] Preferably, the weight percentage of organic co-solvent (S) comprised in the aqueous dispersion (XD), having at a temperature of 293.15 K a vapour pressure of 0.01 kPa or more, is less than 5, more preferably less than 3, most preferably less than 1.

[0090] Preferably, the ratio of the molar amount of blocking agent (BA) over the molar amount of isocyanate groups comprised in polyisocyanate (I) is in the range of from 0.2 to 0.8, more preferably in the range of from 0.3 to 0.7, most preferably in the range of from 0.35 to 0.65.

[0091] In embodiments of the present invention, the blocking agent (BA) is selected from the group consisting of oximes (for example, but not limited to, formamide oxime, acetaldoxime, acetoxime, methylethyl ketoxime, methylisobutyl ketoxime, diethyl ketoxime, diacetyl monoxime, benzophenoxime, cyclopentanoneoxime, cyclohexanoneoxime, or any combinations thereof), pyrazoles (for example, but not limited to, pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-bromo-3,5- dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-benzyl-3,5-dimethylpyrazole, methyl 5-methylpyrazole-3-carboxylate, 3-methyl-5-phenylpyrazole, 3,5-dimethylpyrazole-4-carboxanilide, or any combinations thereof), active methylene compounds (a compound comprising a methylene group directly bonded to two electron withdrawing groups such as for example, but not limited to, dimethyl malonate, diethyl malonate, diisopropyl malonate, ethyl acetoacetate, isopropyl acetoacetate, methyl acetoacetate, isopropyl acetoacetate, acetylacetone, or any combinations thereof), aliphatic alcohols, cycloaliphatic alcohols, aromatic alcohols (for example but not limited to phenol, cardanol, derivatives of cardanol, or any combinations thereof), glycol ethers (for example, but not limited to, butylglycol, butyldiglycol, or any combinations thereof), lactams, mercaptans, imidazoles, triazoles, amines, imines, hydroxylamines, hydroxyalkyl esters (for example, but not limited to, hydroxyethyl(meth)acrylate), and mixtures thereof. More preferably, the blocking agent (BA) is selected from the group consisting of glycol ethers, hydroxyalkyl esters, and mixtures thereof, most preferably selected from the group consisting of butyldiglycol, hydroxyethyl(meth)acrylate, and mixtures thereof.

[0092] In another preferred embodiment the blocking agent (BA) is selected from the group consisting of alpha-hydroxy amide, alpha-hydroxy ester, alpha-hydroxy thioester, or mixtures thereof. As used herein, the term "alpha-hydroxy amide" refers to an organic compound having at least one alpha-hydroxy amide moiety that includes a hydroxyl functional group covalently bonded to an alphacarbon of an amide group. As used herein, the term "alpha-hydroxy ester" refers to an organic compound having at least one alpha-hydroxy ester moiety that includes a hydroxyl functional group covalently bonded to an alpha-carbon of an ester group. As used herein, the term "alpha-hydroxy thioester" refers to an organic compound having at least one alpha-hydroxy thioester moiety that includes a hydroxyl functional group covalently bonded to an alpha-carbon of a thioester group, more preferably the blocking agent (BA) is selected from the group consisting of alkyl glycolamide, alkyl lactamide, and mixtures thereof.

[0093] Preferably, the crosslinking component (X) is substantially free of unblocked (or free) isocyanate group-containing compounds and the water-dilutable paint (P) can be formulated as one-component paint formulation. “Substantially free of unblocked isocyanate group-containing compounds” in the context of the present invention refers to the specific content of free isocyanate groups (based on crosslinking component (X)) preferably being not more than 100 mmol / kg, more preferably being not more than 50 mmol / kg, and most preferably being not more than 20 mmol / kg.

[0094] In embodiments of the present invention, the polyisocyanate (I) is an oligomer based on aromatic, aliphatic or cycloaliphatic diisocyanates, preferably selected from the group consisting of 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,4-naphthylene diisocyanate, 1 ,5-naphthylene diisocyanate, biphenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, and mixtures thereof. As used herein, the wording "oligomer based on aromatic, aliphatic or cycloaliphatic diisocyanates" refers to a polyisocyanate formed by reacting or polymerizing diisocyanate monomers to create molecules with more than two isocyanate groups, wherein the number of repeating units within the polyisocyanate is less than 10, preferably less than 8, most preferably from 2 to 6. Examples include biurets, isocyanurates, or uretdiones derived from diisocyanates such as 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, and mixtures thereof.

[0095] In an alternative and more preferred embodiment, the polyisocyanate (I) is oligomeric MDI, which is the mixture of oligomeric reaction products according to formula (1 ), with n ranging from 0 to 5, and which has on average between 2.0 and 3.0, more preferably from 2.2 to 2.9 isocyanate groups per molecule. Usually, oligomeric MDI is the reaction product of formaldehyde, aniline and phosgene.

[0096]

[0097] The at least one amine (A) is a compound comprising at least one tertiary amine group and additionally at least two groups being reactive towards isocyanate. Preferably, for the majority of molecules referring to amine (A), all the at least two groups being reactive towards isocyanate actually react with isocyanate groups comprised in polyisocyanate (I), thereby forming a reaction product where the at least one tertiary amine group is laterally pending from the (branched) backbone. More preferably, for more than 90% of molecules referring to amine (A), all the at least two groups being reactive towards isocyanate actually react with isocyanate groups comprised in polyisocyanate (I).

[0098] In embodiments of the present invention, the at least one amine (A) is a compound according to formula (2) or according to formula (3), preferably according to formula (2):

[0099] R2 R2

[0100] / /

[0101] TA — R1 — N TA — R1 — C R4

[0102] R3(2)R3(3)

[0103] wherein

[0104] TA is a linear or branched aliphatic tertiary amine, preferably a C1 to C4 dialkylamino group, more preferably a dimethylamino group, or a tertiary amine part of a cyclic aliphatic alkyl radical or of an aromatic alkyl radical,

[0105] R1 is a linear alkyl radical comprising at least one, preferably at least two, more preferably at least three, even more preferably from one to six, most preferably from one to four carbon atom(s); a branched alkyl radical comprising at least two, preferably at least three, even more preferably from two to six, most preferably from two to four carbon atoms; a cyclic aliphatic alkyl radical comprising at least four, preferably at least five, even more preferably from four to eight, most preferably from four to six carbon atoms; or an aromatic alkyl radical comprising at least five, preferably at least six, most preferably six carbon atoms, even most preferably R1 is a linear alkyl radical comprising from two to four carbon atoms,

[0106] N is a nitrogen atom,

[0107] C is a carbon atom,

[0108] R2 is a hydroxyl group, or a linear, branched, or cyclic aliphatic alkyl radical comprising at least one, preferably one, hydroxyl group,

[0109] R3 is a linear, branched, or cyclic aliphatic alkyl radical comprising at least one, preferably one, hydroxyl group,

[0110] R4 is hydrogen, a linear, branched, or cyclic aliphatic alkyl radical comprising from one to six carbon atoms, or an aromatic alkyl radical comprising six carbon atoms, preferably R4 is hydrogen. If TA is a linear or branched aliphatic tertiary amine, R1 is preferably linked to TA through a carbon-nitrogen bond. If TA is a tertiary amine part of a cyclic aliphatic radical, R1 is preferably linked to TA through a carbon-nitrogen bond or through a carboncarbon bond. If TA is a tertiary amine part of an aromatic alkyl radical, R1 is preferably linked to TA through a carbon-carbon bond.

[0111] As used herein, the wording "tertiary amine part of a cyclic aliphatic alkyl radical or of an aromatic alkyl radical" refers to a structural unit where the nitrogen atom of the tertiary amine is a member of the cyclic aliphatic or of the aromatic ring structure. Most preferably, the at least one amine (A) is selected from the group consisting of 1 ,T-{[3-(dimethylamino)propyl]imino}-bis-2-ethanol; 1 ,1'-{[3- (dimethylamino)propyl]imino}-bis-2-propanol (Jeffcat® DPA from Huntsman); 3-dimethylamino-1 ,2-propanediol; N,N-bis-(2-hydroxyethyl)isonicotinamide, and mixtures thereof.

[0112] It is desirable that the aqueous dispersion (XD) has a high non-volatile content. Preferably, the aqueous dispersion (XD) has a non-volatile content (determined according to DIN EN ISO 3251) of from 25.0 to 55.0 %, more preferably of from 30.0 to 55 %, most preferably of from 32 to 55%. Still, the dynamic viscosity of the aqueous dispersion (XD) preferably requires to be in a practical range. It is therefore preferable that the dynamic viscosity of the aqueous dispersion (XD) (determined according to DIN EN ISO 3219) is below 1,000 mPa.s, more preferably below 500 mPa.s, most preferably below 250 mPa.s. Even more preferably, the dynamic viscosity of the aqueous dispersion (XD) ranges from 10 to 1 ,000 mPa.s, more preferably from 10 to 500 mPa.s, most preferably from 10 to 250 mPa.s.

[0113] For the dispersibility of the crosslinking component (X) in water it is necessary that the amine groups of the amine-containing blocked polyisocyanate are at least partially neutralized by at least one neutralizing acid (NA), to form (or thereby forming) cationic salt groups. Preferably, at least 20 %, more preferably at least 25 %, most preferably at least 30 % of the amine groups of the amine-containing blocked polyisocyanate are neutralized by at least one neutralizing acid (NA). Suitable neutralizing acid (NA) may be inorganic, for example, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid and perchloric acid. Suitable acids may also be organic, for example, mono-or poly-carboxylic acids which are optionally substituted with a hydroxyl group, or sulphonic acids. Particularly, the organic acids may be C1-C10-monocarboxylic acids, C1 -C10-dicarboxylic acids, C1-C10-tricarboxylic acids, C1-C10-hydroxymonocarboxylic acids, C1-C10-hydroxydicarboxylic acids, C1-C10-hydroxytricarboxylic acids, C1 -C10-alkyl sulphonic acids, C7-C18-alkyl aryl sulphonic acids, and any combinations thereof. Examples of the organic acids may include, but are not limited to, formic acid, acetic acid, propanoic acid, butanoic acid, lactic acid, glycolic acid, 3-hydroxy butanoic acid, 2-hydroxyisobutanoic acid, malic acid, oxalic acid, malonic acid, methyl malonic acid, succinic acid, methyl succinic acid, adipic acid, pimelic acid, suberic acid, glutaric acid, citric acid, tartaric acid, fumaric acid, benzoic acid, methansulphonic acid and any combinations thereof. Suitable organic acids may particularly be selected from the group consisting of formic acid, acetic acid, propanoic acid, lactic acid, oxalic acid, glycolic acid, citric acid, malic acid, adipic acid, succinic acid, fumaric acid, benzoic acid, methansulphonic acid and any combinations thereof. The molar amount of neutralizing acid (NA) present in the aqueous dispersion (XD) is expressed as the amount of acid equivalents (MEQ acid value) based on the nonvolatile content of the dispersion. As used herein, the term "amount of acid equivalents (MEQ acid value)" refers to the millimoles of neutralized basic functional groups per 100 grams of non-volatile content in the dispersion. It quantifies the amount of neutralizing acid (NA) that neutralizes the basic groups, such as tertiary amine groups, in the resin. A certain amount of acid equivalents (MEQ acid value) is necessary to provide a stable aqueous dispersion, however, a too high amount of acid equivalents is undesirable. Such a high amount of acid equivalents requires a high electrical current during electrodeposition of the dispersion, because more cationic groups need to be discharged in order to deposit the same amount of coating. In turn, the higher the electrical current during electrodeposition, the higher is also the heat generation caused by the metal substrates which demands an energy consuming cooling system. In addition to that, the quality of the coverage of hard-to-reach areas like cavities and edges is usually lower, the higher the electrical current is during deposition. Preferably, the amount of acid equivalents (MEQ acid value determined according to DIN EN ISO 15880) of the aqueous dispersion (XD) is below 40 mmol / 100 g, more preferably below 38 mmol / 100 g, most preferably below 36 mmol / 100 g, based on non-volatile content. The MEQ acid value being below 40 mmol / 100 g indicates a low level of neutralization. More preferably, the amount of acid equivalents of the aqueous dispersion (XD) is from 5 to 40 mmol / 100 g, more preferably from 10 to 38 mmol / 100 g, most preferably from 15 to 36 mmol / 100 g, based on non-volatile content. In order to provide storage stable aqueous dispersions it is usually preferable that the polymer particles or droplets have a small (average) particle size. As used herein, the term "average particle size" refers to the mean diameter of particles in the aqueous dispersion, measured by dynamic light scattering (DLS). An average particle size below 200 nm means that the majority of particles in the dispersion have diameters smaller than 200 nanometers, which influences the stability and application properties of the dispersion. There exist several methods to characterize the (average) particle size of aqueous dispersions, a popular method being based on dynamic light scattering, where the (average) particle size is expressed as Z-average value (or Z-average mean, or z-average diameter, or Z-average particle size). Preferably, the aqueous dispersion (XD) has an average particle size (determined according to DIN ISO 13321) of below 500 nm, more preferably in the range between 10 and 300 nm, most preferably in the range between 30 and 250 nm.

[0114] Any feature of the first aspect can be as correspondingly described in any of the other aspects of the invention.

[0115] In the second aspect, the invention relates to a water-dilutable paint (P) for cathodically depositable electrodip coatings comprising

[0116] a) a cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups;

[0117] b) the aqueous dispersion (XD) of a crosslinking component (X) according to the first aspect of the invention; and

[0118] c) optionally, a curing catalyst.

[0119] The inclusion of the aqueous crosslinker dispersion provides low bake performance to the cathodic electrocoat paint, allowing for curing at lower temperatures compared to traditional systems.

[0120] As used herein, the wording "water-dilutable paint for cathodically depositable electrodip coatings" refers to paints formulated for application by the cathodic electrodeposition process, where the substrate to be coated acts as the cathode, attracting positively charged paint particles from the aqueous dispersion to form a uniform film. This method is commonly used in automotive and industrial coatings for corrosion protection. As used herein, the wording “cationic amino-containing resins which contain hydroxyl groups and / or primary or secondary amine groups” refers to resins that comprise amine groups, preferably tertiary amine groups, as cationic salt groups (if converted into by a neutralizing acid) and / or as substituents which can be (further) converted into cationic salt groups, and that (further also) comprise hydroxyl groups and / or primary or secondary amine groups as isocyanate-reactive functional groups. Examples of cationic amino-containing resins include resins such as amino(meth)acrylic resins, aminopolyurethane resins, amino group-containing polybutadiene resins, epoxy resin-carbon dioxide-amine-reaction products, and epoxy-amine-adduct resins, preferably epoxy-amine-adduct resins. The epoxy-amine-adduct resins preferably are adducts of (unmodified or modified) polyepoxides with primary and / or secondary amines, for example as described in EP 1956056 A2, EP 1171530 A1, US 5236564 A, US 5236564 A and US 6274649 B. Examples of suitable polyepoxides include polyglycidyl ethers obtainable from polyphenols and epihalohydrin, more particularly epichlorohydrin. Preferred polyphenols are, more particularly, bisphenol A and bisphenol F. Suitable polyphenols also include, but are not limited to, 4,4'dihydroxybenzophenone, 1 , 1 -bis(4-hydroxyphenyl)ethane, 1 , 1 -bis(4-hydroxyphenyl)isobutane, 2,2-bis(4-hydroxy-tert-butylphenyl)propane, bis(2-hydroxynaphthyl)methane, 1 ,5-dihydroxynaphthalene, and phenolic novolak resins. Suitable polyepoxides also include, but are not limited to, polyglycidyl ethers of polyhydric alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1 ,4-propylene glycol, 1 ,5-pentanediol, 1 ,2,6-hexanetriol, glycerol, and 2,2-bis(4-hydroxycyclohexyl)propane; polyglycidyl esters of polycarboxylic acids, such as oxalic acid, succinic acid, glutaric acid, terephthalic acid, hexahydrophthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid; hydantoin epoxides, epoxidized polybutadiene, and polyepoxide compounds obtained by epoxidizing an olefinically unsaturated aliphatic compound. Modified polyepoxides are polyepoxides in which some of the reactive groups have been reacted with a modifying compound. Examples of modifying compounds include

[0121] i) compounds containing carboxyl groups,

[0122] for example, (saturated or unsaturated) monocarboxylic acids, such as benzoic acid, 2-ethylhexanoic acid, Versatic acid; aliphatic, cycloaliphatic and / or aromatic dicarboxylic acids of different chain lengths, such as (meth)acrylic acid or poly(meth)acrylic acid, adipic acid, sebacic acid, isophthalic acid, fatty acids or dimeric fatty acids;

[0123] hydroxyalkylcarboxylic acids such as lactic acid, dimethylolpropionic acid;

[0124] or carboxylcontaining polyesters; or

[0125] ii) compounds containing amine groups, for example, diethylamine, ethylhexylamine, diamines with secondary amine groups such as N,N'-dialkylalkylenediamines (e.g. dimethylethylenediamine), N,N'-dialkylpolyoxyalkylenamines (e.g. N,N'-20 dimethylpolyoxypropylenediamine), cyanoalkylated alkylenediamines (e.g. N,N'bis(cyanoethyl)ethylenediamine), cyanoalkylated polyoxyalkylendiamines (e.g. N,N'bis(cyanoethyl)polyoxypropylenediamine), polyaminoamides such as aminoterminated reaction products of diamines, polycarboxylic acids, and monocarboxylic acids, or reaction products of one mole of diaminohexane with two moles of monoglycidyl ether or monoglycidyl ester, especially glycidyl esters of alpha-branched fatty acids such as Versatic acid; or

[0126] iii) compounds containing hydroxyl groups, for example, neopentyl glycol, bisethoxylated neopentyl glycol, neopentyl glycol hydroxypivalate, dimethylhydantoin-N,N'-diethanol, hexane-1,6-diol, hexane-2,5-diol, 1 ,4-bis(hydroxymethyl)cyclohexane, 1, 1-isopropylidenebis(p-phenoxy)-2-propanol, trimethylolpropane, pentaerythritol, or amino alcohols such as triethanolamine, methyldiethanolamine, or hydroxyl-containing alkylketimines, such as aminomethylpropane-1 ,3-diol methylisobutyl ketimine or tris(hydroxymethyl)aminomethane cyclohexanone ketimine, or also polyglycol ethers, polyester polyols, polyether polyols, polycaprolactone polyols, or polycaprolactam polyols of different functionalities and molecular weights; or

[0127] iv) saturated or unsaturated fatty acid methyl esters which are transesterified in the presence of sodium methoxide with hydroxyl groups of the epoxy resins.

[0128] The primary and / or secondary amines suitable for forming adducts with polyepoxides include, but are not limited to, mono- and dialkylamines, such as methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine and methylbutylamine; alkanolamines, such as methylethanolamine and diethanolamine; dialkylaminoalkylamines, such as dimethylaminoethylamine, diethylaminopropylamine and dimethylaminopropylamine; alkylene polyamines, such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine and triethylenetetramine. The amines may contain other groups as well, provided that those groups do not disrupt the reaction of the amine with the epoxide group and not lead to any gelling of the reaction mixture. Secondary amines are particularly suitable for forming adducts with polyepoxides.

[0129] Preferably, a curing catalyst is comprised in the water-dilutable paint (P). As used herein, the term "curing catalyst" refers to a substance added to accelerate the crosslinking reaction during the curing process of the coating. Curing catalysts promote the reaction between the resin and crosslinking agent (crosslinking component) at lower temperatures or shorter times. The curing catalysts which are preferably used for the invention are compounds of elements of groups 4, 7, 8, 9, 12, 13, 14, and 15 of the fourth, fifth and sixth period of the periodic system of elements, particularly preferably, of the elements Ti, Mn, Fe, Co, Ni, Zn, Cd, Ge, Sn, Pb, Sb, and Bi. More preferred curing catalysts are compounds that are well soluble in water, such as salts of these elements that dissociate into ions, in an aqueous system, and chelate compounds of these elements, where the chelate former may be an organic hydroxy acid such as lactic acid, 2,2-bishydroxymethyl propionic acid, an aminoacid such as N,N,N’,N’-ethylenediamine tetraacetic acid, nitrilotriacetic acid, and beta-alanine, or a multifunctional amine, or a hydroxyamine. Other useful compounds are organometallic compounds such as alkoxy metal oxides, and metal salt of organic acids or hydroxy acids. Even more preferred curing catalysts are the methane sulphonates, lactates and bishydroxymethyl-propionates of bismuth, tin, lead, and titanium, as well as mixtures thereof. Most preferably the curing catalyst is the bismuth salt of methane sulphonates, lactates, bishydroxymethyl-propionates, as well as mixtures thereof.

[0130] Alternatively, the curing catalyst (if present in the water-dilutable paint (P)) comprises an organic curing catalyst. As used herein, the term "organic curing catalyst" refers to organic compounds that do not contain metal or complexes with metal that function as curing catalysts. The organic curing catalyst may comprise a guanidine. It will be understood that "guanidine," as used herein, refers to guanidine and derivatives thereof. Examples of suitable guanidines are presented in US 2025 / 0043165 A1. Preferably, the water-dilutable paint (P) comprises a weight percentage of a) from 30 to 80, more preferably from 35 to 70, most preferably from 40 to 70, of the cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups;

[0131] b) from 20 to 70, more preferably from 25 to 65, most preferably from 30 to 60, of the aqueous dispersion (XD) according to the first aspect of the invention; and c) from 0.5 to 10, more preferably from 1 to 8, most preferably from 1 to 5, of the curing catalyst

[0132] based on the total weight of water-dilutable paint (P) being 100%.

[0133] The paint may further include various additives such as grinding resins, emulsifiers, pigments, fillers, anti-cratering additives, waxes, anti-corrosion pigments, and mixtures thereof to enhance its properties and performance. These are typical paint additives used to improve film characteristics, and enhance overall film performance.

[0134] In the context of the present invention, coating is also referred to as film, coating film, and paint film.

[0135] Any feature of the second aspect can be as correspondingly described in any of the other aspects of the invention.

[0136] In the third aspect, the invention relates to a process for making the aqueous dispersion (XD) of the crosslinking component (X) as described in the first aspect. The process provides a controlled way to make the crosslinker dispersion and comprises the following steps:

[0137] a) providing a mixture of the at least one polyol (PO), the at least one blocking agent (BA), and optionally the organic co-solvent (S) at a temperature between 50-150°C, preferably between 60-120°C, more preferably between 70-110°C; b) adding the polyisocyanate(s) (I) to the mixture from step (a), preferably over a period of 0.5-10.0 hours, more preferably over a period of 0.5-8.0 hours, to form (or thereby forming) an intermediate reaction mixture;

[0138] c) adding the amine(s) (A) to the mixture from step (b), preferably over a period of less than 5.0 hours, more preferably over a period of less than 3.0 hours, to continue the reaction;

[0139] d) adding the neutralizing acid(s) (NA), preferably as a dilution in 20-80 % by weight water, to neutralize the mixture; and e) adding water to the mixture from step (d) and stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X).

[0140] Alternatively, the process comprises the following steps:

[0141] a) providing the polyisocyanate(s) (I) at a temperature between 50-150°C, preferably between 60-120°C, more preferably between 70-110°C;

[0142] b) adding a mixture of the at least one polyol (PO), the at least one blocking agent (BA), and optionally the organic co-solvent (S) to the polyisocyanate(s) (I) from step (a), preferably over a period of 0.5-10.0 hours, more preferably over a period of 0.5-8.0 hours, to form (or thereby forming) an intermediate reaction mixture;

[0143] c) adding the amine(s) (A) to the mixture from step (b), preferably over a period of less than 5.0 hours, more preferably over a period of less than 3.0 hours, to continue the reaction;

[0144] d) adding the neutralizing acid(s) (NA), preferably as a dilution in 20-80 % by weight water, to neutralize the mixture; and

[0145] e) adding water to the mixture from step (d) and stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X).

[0146] Further alternatively, the reaction mixture of steps a) to c) is provided in a first vessel and in a second vessel water and the neutralizing acid(s) (NA) is / are provided as a mixture, and the reaction mixture of steps a) to c) is added to the second vessel while stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X). Further alternatively, the reaction mixture of steps a) to d) is provided in a first vessel and in a second vessel water is provided, optionally in a mixture with further neutralizing acid(s) (NA), and the reaction mixture of steps a) to d) is added to the second vessel while stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X).

[0147] Further alternatively, the process comprises the following steps:

[0148] a-1 ) providing a mixture of the at least one polyol (PO), the at least one blocking agent (BA), the amine(s) (A), and optionally the organic co-solvent (S) at a temperature between 30-150°C, preferably between 35-120°C, more preferably between 40-110°C; b-1) adding the polyisocyanate(s) (I) to the mixture from step (a-1 ), preferably over a period of 0.5-10.0 hours, more preferably over a period of 0.5-8.0 hours, to form (or thereby forming) an intermediate reaction mixture;

[0149] c-1) adding the neutralizing acid(s) (NA), preferably as a dilution in 20-80 % by weight water, to neutralize the mixture; and

[0150] d-1 ) adding water to the mixture from step (c-1 ) and stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X).

[0151] Further alternatively, the reaction mixture of steps a-1) to b-1) is provided in a first vessel and in a second vessel water and the neutralizing acid(s) (NA) is / are provided as a mixture, and the reaction mixture of steps a-1) to b-1) is added to the second vessel while stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X). Further alternatively, the reaction mixture of steps a1) to c-1) is provided in a first vessel and in a second vessel water is provided, optionally in a mixture with further neutralizing acid(s) (NA), and the reaction mixture of steps a-1) to c-1) is added to the second vessel while stirring to form (or thereby forming) the aqueous dispersion (XD) of the crosslinking component (X).

[0152] In a further preferred embodiment, the reaction mixture may comprise a reaction catalyst. The reaction catalyst is suitable to promote the reaction between the at least one polyisocyanate(s) (I) and the at least one polyol (PO), the at least one blocking agent (BA) and the amine(s) (A). The reaction catalyst can be the same as or different from the curing catalyst (optionally comprised in the water-dilutable paint (P)), preferably the reaction catalyst is a metal-organic compound that is soluble in the reaction mixture, most preferably the reaction catalyst is Bi-neodecanoate or dibutyl-tin-dilaurate. In embodiments, the aqueous dispersion (XD) comprises the curing catalyst, and / or the additive(s) (e.g. grinding resins, emulsifiers, pigments, fillers, anticratering additives, waxes, anti-corrosion pigments, and mixtures thereof), and / or the cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups. The curing catalyst and / or the additive(s) (e.g. grinding resins, emulsifiers, pigments, fillers, anti-cratering additives, waxes, anti-corrosion pigments, and mixtures thereof) may be added during or after the process for making the aqueous dispersion (XD). The cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups may be added during or after the process for making the aqueous dispersion (XD), preferably the cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups may be added before adding water to the reaction mixture or before the reaction mixture is added to the second vessel where the water is provided.

[0153] Any feature of the third aspect can be as correspondingly described in any of the other aspects of the invention.

[0154] In the fourth aspect, the invention relates to a process for making the cathodic electrocoat paint (P) as described in the second aspect, the process comprising the step of mixing the cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups; the aqueous dispersion (XD) according to the first aspect; and optionally, a curing catalyst. The process comprises mixing the components mentioned (i.e. the cationic amino-containing resin, the aqueous dispersion (XD) and the optional curing catalyst) in any possible sequence to form the paint (P). The curing catalyst is preferably used. Optionally, the curing catalyst, if used, may, at least partially, be (already) present in a pre-mix together with the cationic amino-containing resin and / or together with the aqueous dispersion (XD), and which pre-mix is then further mixed with the aqueous dispersion (XD) or cationic amino-containing resin, and optionally further mixed with further curing catalyst (if any still, i.e. in case the curing catalyst to be used was only partially present in the pre-mix). Further optionally, the curing catalyst, if used, may be introduced into the paint (P) together with additives (e.g. together with grinding resins or together with grinding resins and pigments).

[0155] Any feature of the fourth aspect can be as correspondingly described in any of the other aspects of the invention.

[0156] In the fifth aspect, the invention relates to a coating bath for cathodic electrodeposition comprising the aqueous crosslinker dispersion (XD) of the first or third aspect. As used herein, the wording "coating bath for cathodic electrodeposition" refers to a bath containing the aqueous dispersion and other components necessary for the electrodeposition process. The bath allows for the uniform deposition of the coating onto electrically conductive substrates when an electric current is applied. This bath enables low bake electrocoating processes, providing energy savings and efficiency. Any feature of the fifth aspect can be as correspondingly described in any of the other aspects of the invention. In the sixth aspect, the invention relates to using the aqueous crosslinker dispersion (XD) of the first or third aspect, or using the cathodic electrocoat paint (P) of the second or fourth aspect, for coating a substrate by cathodic electrodeposition. This provides coatings with low bake performance. Preferably, the substrate coated according to the sixth aspect of the invention is an electrically conductive substrate, more preferably a metal substrate.

[0157] Any feature of the sixth aspect can be as correspondingly described in any of the other aspects of the invention.

[0158] The following examples are intended to illustrate the process for making the aqueous dispersion (XD) and the water-dilutable paint (P) according to the invention, the products obtained therefrom and the application thereof and are not intended to limit the invention.

[0159] EXAMPLES

[0160] In the specification, and also in the examples, the following parameters and test methods have been used to describe physicochemical properties of the compounds and substances:

[0161] - amine value (mg KOH / g) according to DIN 53176

[0162] - NCO content (%) according to DIN EN ISO 11909

[0163] - non-volatile content (%) according to DIN EN ISO 3251, 1 hour / 125°C / 1 g - amount of acid equivalents (MEQ acid value) according to DIN EN ISO 15880 - dry film thickness according to DIN EN ISO 2178 (measuring principle 4.3) - Acetone test: 2 mL of acetone were placed onto the coating film and the time measured until the coating film could be scratched.

[0164] Example 1 : Reaction product of propylene carbonate with diethanol amine

[0165] 105 parts by weight of diethanol amine and 102 parts by weight of propylene carbonate were reacted at a temperature of 110 °C in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet until an amine value of less than 14 mg KOH / g was reached. The reaction product predominantly was a carbamate compound comprising two primary and one secondary hydroxyl groups.

[0166] Example 2: Aqueous dispersion (XD) of a crosslinking component (X)

[0167] 487 parts by weight of butyldiglycol, 207 parts by weight of the reaction product of diethanol amine and propylene carbonate from Example 1 and 120 parts by weight of butylcarbitol formal (bis(2-(2-butoxyethoxy)ethoxy)methane, CAS Registry Number 143-29-3) were filled in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet. The initial charge was heated to 80 °C and 990 parts of oligomeric MDI (polyisocyanate having on average 2.6 isocyanate groups per molecule, NCO content 31.9 %) were dosed into the reactor over 60 minutes with continuous stirring. After finishing dosing the temperature was held at 80 °C for further 60 minutes, then 163.5 parts by weight of 1 ,1'-{[3-(dimethylamino)propyl]imino}-bis-propane-2-ol were slowly added to the flask and stirred for another 60 minutes. A mixture of 40 parts by weight of deionized water and 35 parts per weight of formic acid (85 % by weight) were added and stirred for 15 minutes. Then 2508 parts per weight of deionized water were added to the flask obtaining an aqueous dispersion of an amine-containing blocked polyisocyanate. The characteristics of the dispersion are shown in Table 1. The resulting product is an aqueous dispersion of a crosslinking component having tertiary amine groups which are laterally pending from the backbone and where the nitrogen atoms of the laterally pending tertiary amine groups are separated from the backbone by three intervening carbon atoms.

[0168] Example 3: Aqueous dispersion of a crosslinking component not according to the invention

[0169] 487 parts by weight of butyldiglycol, 114 parts by weight of propylene glycol and 240 parts by weight of butylcarbitol formal were filled in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet. The initial charge was heated to 80 °C and 990 parts of oligomeric MDI (polyisocyanate having on average 2.6 isocyanate groups per molecule, NCO content 31.9 %) were dosed into the reactor over 60 minutes with continuous stirring. After finishing dosing the temperature was held at 80 °C for further 60 minutes, then 163.5 parts by weight of 1 ,1'-{[3-(dimethylamino)propyl]imino}-bis-propane-2-ol were slowly added to the flask and stirred for another 60 minutes. A mixture of 40 parts by weight of deionized water and 33 parts per weight of formic acid (85 % by weight) were added and stirred for 15 minutes. Then 10684 parts per weight of deionized water were added to the flask obtaining an aqueous dispersion of an amine-containing blocked polyisocyanate. The characteristics of the dispersion are shown in Table 1. Example 4: Aqueous dispersion of a crosslinking component not according to the invention

[0170] 487 parts by weight of butyldiglycol, 207 parts by weight of the reaction product of diethanol amine and propylene carbonate from Example 1 and 120 parts by weight of buty Icarbitol formal were filled in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet. The initial charge was heated to 80 °C and 891 parts of oligomeric MDI (polyisocyanate having on average 2.6 isocyanate groups per molecule, NCO content 31.9 %) were dosed into the reactor over 60 minutes with continuous stirring. After finishing dosing the temperature was held at 80 °C for further 60 minutes, then 76.7 parts by weight of dimethylaminopropylamine (DMAPA) were slowly added to the flask and stirred for another 60 minutes. A mixture of 40 parts by weight of deionized water and 42.6 parts per weight of formic acid (85 % by weight) were added and stirred for 15 minutes. Then 2510 parts per weight of deionized water were added to the flask obtaining an aqueous dispersion of an amine-containing blocked polyisocyanate. The characteristics of the dispersion are shown in Table 1.

[0171] Example 5: Aqueous dispersion (XD) of a crosslinking component (X)

[0172] 391 parts by weight of hydroxyethyl methacrylate, 207 parts by weight of the reaction product of diethanol amine and propylene carbonate from Example 1, 120 parts by weight of butylcarbitol formal (bis(2-(2-butoxyethoxy)ethoxy)methane, CAS Registry Number 143-29-3), 2 parts of hydroquinone and 4 parts of butylhydroxytoluene were filled in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet. The initial charge was heated to 40 °C and 990 parts of oligomeric MDI (polyisocyanate having on average 2.6 isocyanate groups per molecule, NCO content 31.9 %) were dosed into the reactor over 60 minutes with continuous stirring. The temperature was allowed to raise to 80°C. After finishing dosing the temperature was held at 80 °C for further 60 minutes, then 163.5 parts by weight of 1 ,1'-{[3-(dimethylamino)propyl]imino}-bis-propane-2-ol were slowly added to the flask and stirred for another 60 minutes. A mixture of 40 parts by weight of deionized water and 35 parts per weight of formic acid (85 % by weight) were added and stirred for 15 minutes. Then 2508 parts per weight of deionized water were added to the flask obtaining an aqueous dispersion of an amine-containing blocked polyisocyanate. The characteristics of the dispersion are shown in Table 1. The resulting product is an aqueous dispersion of a crosslinking component having tertiary amine groups which are laterally pending from the backbone and where the nitrogen atoms of the laterally pending tertiary amine groups are separated from the backbone by three intervening carbon atoms.

[0173] Example 6: Aqueous dispersion (XD) of a crosslinking component (X)

[0174] 487 parts by weight of butyldiglycol, 207 parts by weight of the reaction product of diethanol amine and propylene carbonate from Example 1, 120 parts by weight of butylcarbitol formal (bis(2-(2-butoxyethoxy)ethoxy)methane, CAS Registry Number 143-29-3) and 163.5 parts by weight of 1 ,1'-{[3-(dimethylamino)propyl]imino}-bis-propane-2-ol were filled in a 4-necked flask equipped with a stirrer, a condenser, a nitrogen gas inlet and a nitrogen gas outlet. The initial charge was heated to 40 °C and 990 parts of oligomeric MDI (polyisocyanate having on average 2.6 isocyanate groups per molecule, NCO content 31.9 %) were dosed into the reactor over 60 minutes with continuous stirring. The temperature was allowed to raise to a maximum of 100°C. After finishing dosing the temperature was held at 80 °C for further 60 minutes. A mixture of 40 parts by weight of deionized water and 35 parts per weight of formic acid (85 % by weight) were added and stirred for 15 minutes. Then 3031 parts per weight of deionized water were added to the flask obtaining an aqueous dispersion of an amine-containing blocked polyisocyanate. The characteristics of the dispersion are shown in Table 1. The resulting product is an aqueous dispersion of a crosslinking component having tertiary amine groups which are laterally pending from the backbone and where the nitrogen atoms of the laterally pending tertiary amine groups are separated from the backbone by three intervening carbon atoms.

[0175] The aqueous dispersions according to the invention (Example 2, Example 5, Example 6) had a high solids content, a low particle size as well as a low amount of acid equivalents (MEQ acid value). In contrast, the aqueous dispersion of comparative Example 3 had to be diluted to a very low solids content in order to reach an acceptable dynamic viscosity and the particle size was much too high. For comparative Example 4, in order to reach an aqueous dispersion with an acceptable solids content and a low particle size, a high amount of neutralizing acid was necessary and consequently the amount of acid equivalents (MEQ acid value) was too high. The storage stability of the aqueous dispersions was determined by visual evaluation. The aqueous dispersion of comparative Example 3 partially precipitated after 2 weeks of storage at room temperature, whereas the aqueous dispersions of Example 2, Example 5, Example 6 Table 1

[0176]

[0177] and comparative Example 4 did not show any precipitate on storage under the same conditions. In view of the above it is shown that stable dispersions with high solids content, low MEQ acid values, and low particle sizes can be obtained.

[0178] Example 7: Water-dilutable paint for cathodic electrodeposition (CED paint) CED paint was prepared using the aqueous dispersions of crosslinking component according to Example 2, Example 5 and Example 6, accordingly. The dispersion of cationic amino-containing resin was synthesized as described in Example 1 of EP1956056 A2: A mixture of 666 parts by weight of methoxypropanol, 319 parts by weight of bisphenol A, 591 parts by weight of an adduct of 2 mol epoxy resin (based on bisphenol A I epichlorhydrine; epoxy equivalent weight 190) and 1 mol polypropylene glycol with a molecular weight of 400 g / mol and 886 parts by weight of epoxy resin (based on bisphenol A I epichlorhydrine; epoxy equivalent weight 190) was heated to 45°C and stirred for 1 hour. 121 parts by weight of diethanolamine and 81.5 parts by weight of dimethyl aminopropylamine were then added and the batch was stirred for 2 hours at 125°C. The methoxypropanol was then distilled off under vacuum and the batch was diluted with 240 parts by weight of hexyl glycol. After cooling to 95°C and stirring for 30 minutes at 95°C, 48 parts by weight of aqueous formic acid at 50 wt.% were added and the batch was stirred for 30 minutes. The batch was then converted into an aqueous dispersion having a solids content of 37.5 wt.% by adding deionized water. The dispersion of cationic amino-containing resin was then mixed with the aqueous dispersions of crosslinking component in a ratio according to Table 2 and homogenized for 15 min. Then deionized water and Bi-catalyst were added and stirred for another 15 minutes. After that anti-cratering additive was added and mixed for 15 minutes. Finaly, deionized water was added for viscosity adjustment. The resulting CED paints had a non-volatile content of 15%.

[0179] Table 2

[0180]

[0181] 1according to Example 1 of EP1956056 A2

[0182] 2aqueous solution of an organic bismuth salt with a total metal content of 12 % by weight (based on total weight of the Bi-catalyst) and a non-volatile content of 20 %.

[0183] 3aqueous solution of a cationic acrylic copolymer, 25 % solids content

[0184] Example 8: Deposition of CED paint from a coating bath, cure and paint film performance

[0185] The deposition of CED paint was done in a rectangular plastic basin with a capacity of 3.5 liters. A stainless steel electrode was attached to the edge of the basin as an anode and the substrate to be coated was provided as a cathode by immersing in the paint in parallel at a distance of 12 cm. A propeller stirrer was mounted in between, which homogenized the paint near the bottom at 400-500 revolutions per minute. During deposition the paint was maintained at a temperature of 32 °C. The preselected voltage (see Table 3) was applied over a period of 140 seconds. The steel quality of the used substrates was pre-treated steel (GARDOBOND® 26SW42OC, from Chemetall). After coating, the sheet metal was removed from the coating bath and thoroughly rinsed with deionized water, then dried at room temperature, and finally cured in a paint dryer at constant temperature (see Table 3) for 25 minutes.

[0186] To assess the coating properties and layer thickness development in general, a series of depositions was made at different voltages and then baked at 150 °C for 25 minutes. To test the cross-linking density, individual sheets were coated with a dry film thickness of 20 pm (+ / - 2 pm) and then baked at 130, 140, 150, 160 or 180 °C for 25 minutes. Solvent wetting with subsequent scratching (Acetone test) was used to test the crosslinking density. For this purpose, acetone was used as the solvent and a wooden spatula was used for scratching.

[0187] The data from Table 3 demonstrate that a CED paint based on the aqueous dispersion (XD) of a crosslinking component (X) can be deposited and the resulting films show low bake performance (i.e. good acetone resistance at a curing temperature of 140°C and above), even without the use of classical low bake blocking agents (such as MEKO or pyrazoles). This leads to energy savings and reduced processing times as well as to a reduction of potential regulatory concerns associated with traditional blocking agents. Table 3

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[0189]

Claims

CLAIMS1. Aqueous dispersion (XD) of a crosslinking component (X) for cationic aminocontaining resins which contain hydroxyl groups and / or primary or secondary amine groups, the crosslinking component (X) being an amine-containing blocked polyisocyanate and the crosslinking component (X) being the reaction product of a reaction mixture comprisinga) at least one polyisocyanate (I) comprising more than 2 isocyanate groups per molecule,b) at least one polyol (PO) comprising at least three hydroxyl groups per molecule, wherein two of the hydroxyl groups are more reactive towards isocyanate than the other one(s),c) at least one amine (A) comprising at least one tertiary amine group and additionally at least two groups being reactive towards isocyanate,d) at least one blocking agent (BA),e) at least one neutralizing acid (NA), andf) optionally an organic co-solvent (S);the at least one amine (A) having at least one tertiary amine group which is laterally pending from the backbone of the crosslinking component (X), and the nitrogen atom of the at least one laterally pending tertiary amine group being separated from the backbone of the crosslinking component (X) by at least one intervening atom.

2. The aqueous dispersion (XD) according to claim 1, wherein the reaction mixture comprisesa) from 20 to 80 % by weight of the at least one polyisocyanate (I),b) from 1 to 30 % by weight of the at least one polyol (PO),c) from 1 to 15 % by weight of the at least one amine (A),d) from 10 to 50 % by weight of the at least one blocking agent (BA),e) from 0.5 to 8 % by weight of the at least one neutralizing acid (NA), and f) from 0 to 20 % by weight of the optional organic co-solvent (S);wherein the sum of the weight percentages of (I), (PO), (A), (BA), (NA) and (S) equals to 100 % by weight.

3. The aqueous dispersion (XD) according to claim 1 or 2, wherein the non-volatile content is from 25.0 to 55.0 %.

4. The aqueous dispersion (XD) according to any one of claims 1 to 3, wherein the amount of acid equivalents (MEQ acid value) is below 40 mmol / 100 g, based on non-volatile content.

5. The aqueous dispersion (XD) according to any one of claims 1 to 4, wherein the average particle size is below 500 nm.

6. The aqueous dispersion (XD) according to any one of claims 1 to 5, wherein the polyisocyanate (I) is an oligomer based on aromatic, aliphatic or cycloaliphatic diisocyanates, preferably selected from the group consisting of 1 ,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,4- naphthylene diisocyanate, 1 ,5-naphthylene diisocyanate, biphenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'- diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2,2- diphenylpropane-4,4'-diisocyanate, and mixtures thereof.

7. The aqueous dispersion (XD) according to any one of claims 1 to 5, wherein the polyisocyanate (I) is oligomeric MDI.

8. The aqueous dispersion (XD) according to any one of claims 1 to 7, wherein the at least one polyol (PO) comprises two primary hydroxyl groups and at least one secondary or tertiary hydroxyl group.

9. The aqueous dispersion (XD) according to any one of claims 1 to 8, wherein the at least one polyol (PO) is the reaction product of a cyclic alkylene carbonate (CAC) with an alkanolamine (AA).

10. The aqueous dispersion (XD) according to any one of claims 1 to 9, wherein the at least one amine (A) is a compound according to formula (2) or according to formula (3):R2 R2 / / TA — R1 — N TA — R1 — C R4R3(2)R3(3)whereinTA is a linear or branched aliphatic tertiary amine, or a tertiary amine part of a cyclic aliphatic alkyl radical or of an aromatic alkyl radical,R1 is a linear alkyl radical comprising at least one carbon atom, a branched alkyl radical comprising at least two carbon atoms, a cyclic aliphatic alkyl radicalcomprising at least four carbon atoms, or an aromatic alkyl radical comprising at least five carbon atoms,N is a nitrogen atom,C is a carbon atom,R2 is a hydroxyl group, or a linear, branched, or cyclic aliphatic alkyl radical comprising at least one hydroxyl group,R3 is a linear, branched, or cyclic aliphatic alkyl radical comprising at least one hydroxyl group,R4 is hydrogen, a linear, branched, or cyclic aliphatic alkyl radical comprising from one to six carbon atoms, or an aromatic alkyl radical comprising six carbon atoms.

11. The aqueous dispersion (XD) according to any one of claims 1 to 10, wherein the at least one amine (A) is selected from the group consisting of 1,1'-{[3- (dimethylamino)propyl]imino}-bis-2-ethanol; 1 ,1'-{[3-(dimethylamino)propyl]imino}- bis-2-propanol; 3-dimethylamino-1,2-propanediol; N,N-bis-(2- hydroxyethyl)isonicotinamide, and mixtures thereof.

12. The aqueous dispersion (XD) according to any one of claims 1 to 11, wherein the at least one blocking agent (BA) is selected from the group consisting of oximes, pyrazoles, active methylene compounds, aliphatic alcohols, cycloaliphatic alcohols, aromatic alcohols, glycol ethers, lactams, mercaptans, imidazoles, triazoles, amines, imines, hydroxylamines, hydroxyalkyl esters, and mixtures thereof.

13. The aqueous dispersion (XD) according to any one of claims 1 to 12, wherein the weight percentage of organic co-solvent (S), having at a temperature of 293.15 K a vapour pressure of 0.01 kPa or more, is less than 5.

14. Water-dilutable paint (P) for cathodically depositable electrodip coatings comprisinga) a cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups;b) the aqueous dispersion (XD) according to any one of claims 1 to 13;c) optionally, a curing catalyst.

15. The water-dilutable paint (P) according to claim 14 comprising one or more additive(s) selected from the group consisting of grinding resins, emulsifiers, pigments, fillers, anti-cratering additives, waxes, anti-corrosion pigments, and mixtures thereof.

16. A process for making the aqueous dispersion (XD) according to any one of claims 1 to 13, the process comprising the steps ofa) providing a mixture of the at least one polyol (PO), the at least one blocking agent (BA), and optionally the organic co-solvent (S), at a temperature of between 50 and 150°C;b) adding to the mixture of step a) the at least one polyisocyanate (I), preferably over the course of 0.5 to 10.0 hours;c) adding to the mixture of step b) the at least one amine (A), preferably over a period of less than 5.0 hours;d) adding to the mixture of step c) the at least one neutralizing acid (NA), preferably the neutralizing acid (NA) is added as a dilution in water at a weight percentage between 20 and 80, based on the total weight of neutralizing acid (NA) and water being 100 %; ande) adding water to the mixture of step d) and stirring the mixture to form the aqueous dispersion (XD).

17. A process for making the aqueous dispersion (XD) according to any one of claims 1 to 13, the process comprising the steps ofa-1 ) providing a mixture of the at least one polyol (PO), the at least one blocking agent (BA), the amine(s) (A), and optionally the organic co-solvent (S) at a temperature between 30 and 150°C, preferably between 35 and 120°C, more preferably between 40 and 110°C;b-1) adding the polyisocyanate(s) (I) to the mixture from step (a-1), preferably over the course of 0.5 to 10.0 hours, more preferably over the course of 0.5 to 8.0 hours;c-1 ) adding the at least one neutralizing acid(s) (NA), preferably the neutralizing acid (NA) is added as a dilution in water at a weight percentage between 20 and 80, based on the total weight of neutralizing acid (NA) and water being 100 %; andd-1 ) adding water to the mixture from step (c-1 ) and stirring the mixture to form the aqueous dispersion (XD) of the crosslinking component (X).

18. A process for making the water-dilutable paint (P) according to claim 14 or 15, the process comprising the step of mixing the cationic amino-containing resin which contains hydroxyl groups and / or primary or secondary amine groups; the aqueousdispersion (XD) according to any one of claims 1 to 13; and optionally, a curing catalyst.

19. The process according to claim 18, wherein the curing catalyst is, at least partially, comprised as a pre-mix in the cationic amino-containing resin and / or in the aqueous dispersion (XD).

20. A coating bath for cathodic electrodeposition comprising the aqueous dispersion (XD) according to any one of claims 1 to 13, or comprising the aqueous dispersion (XD) prepared by the process according to claim 16 or 17.

21. Use of the aqueous dispersion (XD) according to any one of claims 1 to 13 or obtained by the process according to claim 16 or 17, or use of the water-dilutable paint (P) according to claim 14 or 15 or obtained by the process according to claim 19 or 19, for coating a substrate by cathodic electrodeposition.

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