Aqueous dispersion containing cationic polyvinyl alcohol-modified polymer particles and an aqueous electrodeposition coating material containing the dispersion

Abstract

The present invention relates to an aqueous dispersion comprising cationic polyvinyl alcohol modified polymer particles, an aqueous electrocoating material comprising said dispersion, and a method for producing a substrate at least partially coated with said aqueous electrocoating material. The aqueous dispersion can be prepared by reacting an intermediate comprising at least one polyvinyl alcohol polymer chain with a compound comprising at least one epoxide group and at least two blocked primary amino groups. The aqueous coating composition comprising said aqueous dispersion provides improved leveling properties during film formation and improved edge protection of the substrate without adversely affecting surface roughness and adhesion and deposition properties.

Description

Technical Field

[0001] The present invention relates to an aqueous dispersion containing cationic polyvinyl alcohol-modified polymer particles, an aqueous electrodeposition coating material containing the dispersion, and a method for producing a substrate at least partially coated with the aqueous electrodeposition coating material. The aqueous dispersion can be prepared by reacting an intermediate containing at least one polyvinyl alcohol polymer chain with a compound containing at least one epoxide group and at least two blocked primary amino groups. The aqueous coating composition containing the aqueous dispersion improves the leveling properties during film formation, improves the edge protection of the substrate, and does not adversely affect the surface roughness, adhesion, and deposition properties.

Background Art

[0002] A common requirement in the automotive sector is that the metal components used in manufacturing must be protected from corrosion. The requirements regarding corrosion prevention to be achieved are very strict, especially because manufacturers often provide guarantees against rust perforation over the years. Such corrosion prevention is usually achieved by coating the component or the substrate used in its manufacture with at least one coating suitable for the purpose, typically an electrocoating.

[0003] The electrocoating process can be either anodic or cathodic. Typically, the article to be coated functions as the cathode. The electrocoating process is economically and environmentally advantageous because of the high transfer efficiency of the coating resin to the substrate and the low concentration of organic solvents when used. Another advantage of electrodeposition coating compositions and processes is that the applied coating composition forms a uniform and continuous layer on various metal substrates regardless of shape or configuration. This is particularly advantageous when applying the coating as an anticorrosion coating on substrates with irregular surfaces such as the body of an automobile. A uniform and continuous coating layer formed on all parts of the metal substrate provides the maximum anticorrosion effect.

[0004] Electrodeposition coating baths typically contain an aqueous dispersion or emulsion of a film-forming material such as an epoxy resin having ion stabilization. The dispersion is typically a two-phase system of one or more finely divided solids, liquids, or combinations thereof in a continuous liquid medium such as water or a mixture of water and an organic co-solvent. An emulsion is a dispersion of droplets in a liquid medium, preferably water or a mixture of water and various co-solvents. Thus, an emulsion is a type of dispersion.

[0005] For automotive or industrial applications, the electrodeposition coating composition is formulated to be a curable composition by using a self-crosslinking resin or by including a crosslinking agent. During electrodeposition, the coating composition containing the ionically charged resin is submerged in an electrodeposition coating bath in which the charged resin is dispersed, and then a potential is applied between the substrate and an electrode of opposite charge, for example, a stainless steel electrode, to deposit it on the conductive substrate. The charged coating particles are plated or deposited on the conductive substrate, and then the coated substrate is heated to cure the coating.

[0006] Suitable automotive metals include cold rolled steel ("CRS"), electrogalvanized steel ("EGS"), hot dip galvanized steel ("HDG"), galvanneal (annealed hot dip galvanized steel), aluminum and aluminum alloys, and other zinc alloy-coated metals. To improve the adhesion of the electrodeposition coating to the metal surface, the metal is typically treated with a zinc phosphate conversion coating.

[0007] An ongoing problem with cathodic electrocoating compositions has been the lack of edge protection or edge coverage of the substrate. Said edge protection is usually a compromise between edge coverage and good fluidity / leveling of the coating film surface formed after application. In the art, using cationic epoxy microgels in electrocoating compositions to improve edge coverage is known, particularly for high film build electrocoating in the ASM (Automotive Supply Metals) market. This is because the presence of these microgels significantly increases the melt viscosity, thereby reducing the flow of the coating composition applied away from the edges of the substrate. However, this significant increase in melt viscosity no longer provides sufficient leveling of the coating composition applied on the substrate, and thus the coating surface becomes rough.

[0008] In the art, it is also known to add water-soluble polyvinyl alcohol polymers to aqueous electrocoating compositions to enhance edge protection. Without wishing to be bound by this theory, the presence of the polyvinyl alcohol polymer is thought to cause aggregation of the inorganic pigments present in the composition after deposition, thereby forming a highly viscous layer close to the substrate that also covers the edges. However, the edge coverage achieved by said viscous layer is very low and is not necessarily sufficient to achieve the desired edge protection.

[0009] Therefore, it would be advantageous to have a polymer resin that can be used in an aqueous electrocoating material as a binder, which provides a higher film thickness at the edges of the substrate and thus leads to improved edge protection. At the same time, said binder should provide a sufficiently low-viscosity melt layer at the coating surface to achieve good fluidity / leveling properties of the applied coating material. However, the improvement in edge protection should not adversely affect the storage stability or deposition process of the electrocoating material. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0010] Therefore, an object of the present invention is to provide a polymer resin that can be incorporated into an aqueous electrodeposition coating material, which can bring a higher film thickness of the electrodeposition coating material to the edge of a substrate, and thus improve the edge coverage rate. Furthermore, the cured layer obtained from the aqueous electrodeposition coating material should have sufficient surface smoothness and adhesion to the substrate. Moreover, the aqueous electrodeposition coating material should have high storage stability, appropriate particle size, filterability, and electrochemical deposition properties.

Means for Solving the Problems

[0011] The above object is achieved by the subject matter recited in the claims and by the preferred embodiments of that subject matter described in the following description.

[0012] Accordingly, a first subject of the present invention is an aqueous dispersion (AD) containing cationic polymer particles, wherein the aqueous dispersion (AD) a) preparing an aqueous dispersion of an intermediate (I1) by reacting a compound (C1) containing at least one free isocyanate group and at least two epoxide groups with (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and then subsequently dispersing the intermediate (I1) in water by a process; b) reacting the aqueous dispersion of the intermediate (I1) obtained in step (a) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups; c) optionally, diluting the aqueous dispersion with an aqueous solution, and d) optionally, at least partially removing the organic solvent present in the dispersion obtained in step (c), obtained by at least one acid is present in step a) and / or step b) and / or step c).

[0013] The aqueous dispersion (AD) identified above is also referred to hereinafter as the aqueous dispersion of the present invention and is thus the subject matter of the present invention. Preferred embodiments of the aqueous dispersion of the present invention will be apparent from the following description and from the dependent claims.

[0014] In light of the prior art, what was unexpected and unpredictable to those skilled in the art was that the object underlying the present invention could be achieved by covalently bonding a polyvinyl alcohol polymer to a cationic epoxy microgel. The polyvinyl alcohol polymer covalently bonded to the cationic epoxy microgel acts as a physical anchor function for the pigment-rich layer, whereby the cationic microgel is fixed to the layer, resulting in a high film thickness at the edge of the substrate. Further, due to the anchor function, the cationic microgel is retained inside the formed coating layer, and a certain stratification having a low-viscosity molten layer is formed on the coating surface. Said stratification is necessary for good fluidity and leveling properties. The cationic epoxy microgel functionalized with a polyvinyl alcohol polymer can be formulated as an aqueous dispersion and can be incorporated into an aqueous electrocoating composition as a binder without any difficulty. The incorporation of said functionalized microgel does not adversely affect the adhesion of the coating film and the cured coating layer and the deposition characteristics of the electrocoating composition.

[0015] A further subject matter of the present invention is a method for preparing an aqueous dispersion (AD) containing cationic polymer particles, said method comprising the following steps: (1) Preparing an aqueous dispersion of an intermediate (I1) by reacting a compound (C1) containing at least one free isocyanate group and at least two epoxide groups with (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and subsequently dispersing the intermediate (I1) in water by a process (2) Reacting the aqueous dispersion of the intermediate (I1) obtained in step (1) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups, (3) Optionally, diluting the aqueous dispersion with an aqueous solution, and (4) Optionally, at least partially removing the organic solvent present in the dispersion obtained after step (3), comprising, At least one acid is present in step (1) and / or step (2) and / or step (3).

[0016] Another subject of the present invention is the following components, (A) At least one aqueous dispersion (AD) of the present invention, or at least one aqueous dispersion (AD) prepared by the method of the present invention, (B) At least one further binder B different from the cationic polymer particles contained in the aqueous dispersion (AD), (C) At least one crosslinking agent (CL), (D) At least one pigment, (E) Optionally at least one additive, and (F) Optionally at least one catalyst which is an aqueous electrocoating material.

[0017] Yet another subject of the present invention is a method for producing a substrate that is at least partially coated, said method comprising the following steps: (a) Contacting the substrate at least partially with the aqueous electrocoating material (ECM) of the present invention, (b) Forming a coating film from the aqueous electrocoating material, (c) Optionally, rinsing the coating film formed in step (b) with an aqueous solution (b), (d) Curing the coating film obtained after step (b) or optionally (c), and (e) Optionally, applying at least one further coating layer and curing said coating layer comprising.

[0018] The last subject of the present invention is a substrate at least partially coated by the method of the present invention.

Embodiments for Carrying Out the Invention

[0019] For determining certain characteristic variables, the measuring methods used in the context of the present invention can be found in the Examples section. Unless otherwise indicated, these measuring methods are used to determine the respective characteristic variables. In the context of the present invention, when citing a standard without any indication of an effective official period, the citation is, implicitly, the version of the standard effective on the filing date, or, if no effective version exists at that time, the latest version.

[0020] Any film thickness reported in the context of the present invention should be understood as the dry film thickness. Thus, in each case, this is the thickness of the cured film. Therefore, when it is reported that a coating material is applied at a specific film thickness, this means that the coating material is applied so as to have the described film thickness after curing.

[0021] Any temperature revealed in the context of the present invention should be understood as the ambient temperature of the room in which the substrate or the coated substrate is placed. Thus, it does not mean that the substrate itself is required to have that temperature.

[0022] The aqueous dispersion of the present invention: The aqueous dispersion of the present invention contains cationic polymer particles, and in the particles, the polymer exists in the form of relatively small individual particles or individual microparticles. The microparticles are preferably at least partially intramolecularly crosslinked. The latter means that the polymer structure present in the particles corresponds to a typical macroscopic network having a three-dimensional network structure.

[0023] The cationic polymer particles preferably exhibit a structure intermediate between a branched crosslinked system and a macroscopic crosslinked system, and thus combine the properties of a macromolecule having a network structure and being soluble in a suitable organic solvent with an insoluble macroscopic network. Therefore, the fraction of the crosslinked polymer can only be determined, for example, by separating the solid polymer after removing water and any organic solvent, and then extracting the fraction of the polymer that is not intramolecularly crosslinked. The phenomenon utilized here is that microgel particles, which are originally soluble in a suitable organic solvent, retain their internal network structure even after isolation and behave like a macroscopic network in the solid state.

[0024] The expression "aqueous" is known to those skilled in the art in this context. It basically refers to a system that contains a significant proportion of water as the dispersion medium rather than consisting solely or predominantly of an organic solvent (also called a solvent) as the dispersion medium. Preferred embodiments of the aqueous characteristics defined based on the maximum amount of the organic solvent and / or based on the amount of water are described below.

[0025] An aqueous dispersion (AD) is obtained by reacting an aqueous dispersion of an intermediate (I1) containing a polyvinyl alcohol polymer group with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups. When diluted with water, the blocked primary amino groups are deblocked, and thus cationic polymer particles are obtained. The cationic polymer particles are at least partially neutralized with at least one acid to promote the dispersion of the cationic particles in water.

[0026] Aqueous dispersion of intermediate (I1): An aqueous dispersion of an intermediate (I1) containing a polyvinyl alcohol polymer group can be prepared by (a) reacting an aqueous solution (C2a-i) of a polyvinyl alcohol polymer with a compound (C1) containing free isocyanate groups and epoxy groups, or (b) reacting a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent with the compound (C1), and then dispersing the prepared intermediate (I1) in water (step (a)). Particularly preferably, the aqueous dispersion of the intermediate (I1) is prepared by alternative (a), i.e., by reacting an aqueous solution (C2a-i) of a polyvinyl alcohol polymer with the compound (C1) in the presence of at least one acid, which is described in detail below. When the aqueous dispersion (AD) prepared from these intermediates (I1) is used in an aqueous electrodeposition coating material, the surface roughness is reduced and the edge coverage of a substrate coated with the aqueous electrodeposition coating material is improved.

[0027] Preferred compounds (C1) contain exactly one free isocyanate group and exactly two epoxide groups. Such compounds (C1) have an epoxy equivalent weight (EEW) of 300 to 700 g / equivalent, preferably 350 to 650 g / equivalent, more preferably 400 to 600 g / equivalent, even more preferably 450 to 550 g / equivalent, and very preferably 500 to 530 g / equivalent, determined in accordance with DIN EN ISO3001:1999-11.

[0028] Suitable compounds (C1) useful for the preparation of the aqueous intermediate (I1) can be obtained by reacting at least one compound (C1-1) containing at least two epoxide groups, particularly at least three epoxide groups, with at least one compound (C1-2) containing at least one amine group, and further reacting the resulting product with at least one compound (C1-3) containing at least two free isocyanate groups.

[0029] Particularly preferably, the compound (C1-1) is a reaction product of propoxylated pentaerythritol and epichlorohydrin.

[0030] Suitable amine group-containing compound (C1-2) is a secondary amine, preferably C1-C 10 Dialkylamine, more preferably C2-C6 dialkylamine, and very preferably C3 dialkylamine may be selected.

[0031] The compound (C1-3) containing at least two free isocyanate groups is preferably an alicyclic, aliphatic-alicyclic, aromatic, aliphatic-aromatic and / or alicyclic-aromatic diisocyanate, dimers and trimers of the described diisocyanates, and mixtures thereof, preferably aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane 4,4'-diisocyanate, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, and m-tetramethylxylylene diisocyanate (m-TMXDI), and very preferably isophorone diisocyanate.

[0032] Compounds (C1-1), (C1-2) and (C1-3) may be reacted in a molar ratio of 1:5:5 to 1:1:1, preferably 1:3:3 to 1:1:1, and very preferably 1:1:1.

[0033] In the context of the present invention, the term "polyvinyl alcohol polymer" refers to a random copolymer or block copolymer containing polymer building blocks of general formula (I), or a homopolymer consisting of polymer building blocks of general formula (I): -[-C(R 1 )-C(R 1 )(OH)-]- (I).

[0034] The polyvinyl alcohol polymer is advantageous according to the present invention and is therefore preferably used. The polymer building blocks of formula (I) may be linked head-to-head or head-to-tail. Advantageously, a substantial majority of the polymer building blocks of formula (I) are linked head-to-tail.

[0035] Residue R in formula (I) 1 is selected from a hydrogen atom, or a substituted or unsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl group.

[0036] Examples of suitable alkyl groups are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, amyl, hexyl, and 2-ethylhexyl. Examples of suitable cycloalkyl groups are cyclobutyl, cyclopentyl, and cyclohexyl. Examples of suitable alkylcycloalkyl groups are methylenecyclohexane, ethylenecyclohexane, and propane-1,3-diylcyclohexane.

[0037] Examples of suitable cycloalkylalkyl groups are 2-, 3- and 4-methyl-, -ethyl-, -propyl- and -butylcyclohex-1-yl. Examples of suitable aryl groups are phenyl, naphthyl, and biphenylyl. Examples of suitable alkylaryl groups are ethylene- and propane-1,3-diyl-benzene. Examples of suitable cycloalkylaryl groups are 2-, 3- and 4-phenylcyclohex-1-yl. Examples of suitable arylalkyl groups are 2-, 3- and 4-methyl-, -ethyl-, -propyl- and -butylphen-1-yl. Examples of suitable arylcycloalkyl groups are 2-, 3- and 4-cyclohexylphen-1-yl.

[0038] The above group R 1may be substituted. For this purpose, electron-withdrawing or electron-donating atoms or organic groups may be used. Examples of suitable substituents are halogen atoms, especially chlorine or fluorine, nitrile groups, nitro groups, partially or fully halogenated, especially chlorinated and / or fluorinated, alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl, cycloalkylaryl, arylalkyl and arylcycloalkyl groups, those exemplified above, especially tert-butyl, aryloxy, alkyloxy and cycloalkyloxy groups, especially phenoxy, naphthoxy, methoxy, ethoxy, propoxy, butyloxy or cyclohexyloxy, arylthio, alkylthio and cycloalkylthio groups, especially phenylthio, naphthylthio, methylthio, ethylthio, propylthio, butylthio or cyclohexylthio, hydroxyl groups, and / or primary, secondary and / or tertiary amino groups, especially amino, N-methylamino, N-ethylamino, N-propylamino, N-phenylamino, N-cyclohexylamino, N,N-dimethylamino, N,N-diethylamino, N,N-dipropylamino, N,N-diphenylamino, N,N-dicyclohexylamino, N-cyclohexyl-N-methylamino or N-ethyl-N-methylamino.

[0039] Group R 1 When mainly contains hydrogen atoms, that is, when other groups R 1 are present only to a small extent, it is advantageous according to the present invention. In the context of the present invention, the term "to a small extent" means that it preferably changes and does not impair or completely change the performance characteristics of the polyvinyl alcohol polymer, especially the solubility profile in water. Group R 1 When contains only hydrogen atoms, that is, when the polymer building block of formula (I) is derived from virtual polyvinyl alcohol, particularly advantageous results are obtained. Therefore, polyvinyl alcohol polymers containing these polymer building blocks are particularly preferably used.

[0040] In addition to the polymer building blocks of general formula (I), the polyvinyl alcohol polymers for use according to the invention in particular comprise polymer building blocks of general formula (II) -[-C(R 2 )-C(R 2 )(OC(O)R 3 )-] (II) and further contain.

[0041] In general formula (II), the group R 2 has the definition as shown above in relation to the residue R 1 , and a hydrogen atom is also particularly advantageous here and is therefore particularly preferably used.

[0042] The group R 3 represents an alkyl group having 1 to 10 carbon atoms, preferably methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, amyl, hexyl, or 2-ethylhexyl, and particularly preferably methyl. Thus, a particularly preferred polymer building block of general formula (II) is derived from vinyl acetate. The polymer building blocks II may be linked head-to-head or head-to-tail. Advantageously, most of the polymer building blocks of general formula (II) are linked head-to-tail.

[0043] Polyvinyl alcohol polymers containing the building blocks of general formulas (I) and (II) are particularly preferably used within the scope of the present invention.

[0044] The polyvinyl alcohol polymer may further contain conventional and known ethylenically unsaturated monomers, such as the following. - (Meth)acrylate esters substantially free of acid groups, - Monomers having at least one hydroxyl group per molecule and substantially free of acid groups, such as hydroxyalkyl esters of acrylic acid, methacrylic acid or other alpha, beta-olefinically unsaturated carboxylic acids, derived from alkylene glycols esterified with an acid or obtainable by reacting an alpha, beta-olefinically unsaturated carboxylic acid with an alkylene oxide, - Monomers having at least one acid group per molecule convertible into the corresponding acid anion group, - Vinyl esters of alpha-branched monocarboxylic acids having 5 to 18 carbon atoms in the molecule, - Reaction products of acrylic acid and / or methacrylic acid with glycidyl esters of alpha-branched monocarboxylic acids having 5 to 18 carbon atoms per molecule, - Cyclic and / or acyclic olefins, such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, cyclohexene, cyclopentene, norbornene, butadiene, isoprene, cyclopentadiene and / or dicyclopentadiene, especially ethylene, - (Meth)acrylamide, - Monomers containing an epoxy group, such as glycidyl esters of ethylenically unsaturated carboxylic acids, - Vinyl aromatic hydrocarbons, - Nitriles, - Vinyl compounds, especially vinyl halides and / or vinylidene dihalides, N-vinylpyrrolidone or vinyl ethers, and - Allyl compounds, especially allyl ethers and allyl esters.

[0045] When these monomers are used, they are present only to a minor extent in the polyvinyl alcohol polymer, but this term is also used here in the meaning explained above. Among these monomers, acyclic olefins, especially ethylene and propylene, especially ethylene, offer special advantages and are preferably used if necessary.

[0046] Advantageously, the polyvinyl alcohol polymer has a degree of polymerization of 100 to 20,000, preferably 200 to 15,000, particularly preferably 300 to 12,000, and especially 400 to 10,000.

[0047] The amount of the polymer building block of general formula (I) in the polyvinyl alcohol polymer is advantageously 50 to 99.9 mol%, more preferably 60 to 99.9 mol%, even more preferably 70 to 99 mol%, and very preferably 80 to 99 mol%.

[0048] In the context of the present invention, polyvinyl alcohol polymers containing particularly advantageous polymer building blocks of general formulas (I) and (II) bring very special advantages and are thus very particularly preferably used according to the present invention. These polyvinyl alcohol polymers are also referred to as polyvinyl alcohol for short by those skilled in the art.

[0049] As is known, polyvinyl alcohol is not available directly from the polymerization process but is instead prepared by a polymer-analogous reaction of hydrolysis of polyvinyl acetate. Particularly advantageous commercially customary polyvinyl alcohols have a molecular weight of 10,000 to 500,000 Da, preferably 15,000 to 320,000 Da, and particularly 20,0000 to 300,000 Da.

[0050] Particularly preferably, the polyvinyl alcohol polymer has a viscosity at 20 °C of at least 2 mPa·s, preferably 2 to 60 mPa·s, more preferably 10 to 60 mPa·s, even more preferably 30 to 50 mPa·s, very preferably 45 to 49 mPa·s, as determined at a concentration of 4% by mass in water in accordance with DIN 53015:2018-07.

[0051] Preferred polyvinyl alcohol polymers have a degree of hydrolysis of 70 to 100 mol%, preferably 70 to 95 mol%, very preferably 86 to 89 mol%.

[0052] The aqueous solution (C2a-i) preferably contains 5 to 15% by mass, preferably 5 to 10% by mass, of a polyvinyl alcohol polymer and 85 to 95% by mass, preferably 90 to 95% by mass, of water, in each case based on the total mass of the aqueous solution (C2a-i). Particularly preferably, the aqueous solution (C2a-i) contains 5 or 10% by mass of a polyvinyl alcohol polymer and 90 to 95% by mass of water, in each case based on the total mass of the aqueous solution (C2a-i).

[0053] Compound (C1) may be reacted with compound (C2a-i) in a ratio of 1:10 to 10:1, preferably 1:10 to 2:1, very preferably 1:10 to 1:1, where each ratio is based on the solids content of compound (C1) and (C2a-i).

[0054] When the aqueous dispersion of intermediate (I1) is prepared by the alternative (b) described above, dispersion (C2a-ii) preferably contains 50 to 60% by mass of a polyvinyl alcohol polymer and 40 to 50% by mass of at least one organic solvent S1, in each case based on the total mass of dispersion (C2a-ii).

[0055] In this regard, suitable organic solvents S1 are selected from aliphatic and / or aromatic hydrocarbons, ketones, esters, amides, methylal, butyral, 1,3-dioxolane, glycerol formal, hydrocarbons and mixtures thereof, preferably ketones, very preferably methyl isobutyl ketone.

[0056] Compound (C1) may be reacted with compound (C2a-ii) in a mass ratio of 1:20 to 1:10, preferably 1:17 to 1:15.

[0057] Compound (C3): The aqueous dispersion of intermediate (I1) is reacted with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups (step (b)). Particularly preferably, at least one acid is present during said reaction.

[0058] A suitable compound (C3) can be obtained by reacting at least one compound (C3-1) containing at least one epoxide group with at least one compound (C3-2) containing at least one aromatic group and at least two hydroxyl groups in the presence of at least one solvent S2, and then further reacting the resulting product with at least one polyamine (C3-3) containing at least two blocked primary amino groups and at least one free secondary amino group.

[0059] A preferred compound (C3-1) has an epoxy equivalent weight (EEW) of 100 - 300 g / equivalent, more preferably 150 - 250 g / equivalent, very preferably 170 - 200 g / equivalent, determined in accordance with DIN EN ISO3001:1999-11, and / or a viscosity at 20 °C of 30,000 - 50,000 mPa*s, very preferably 35,000 - 37,000 mPa*s, determined in accordance with DIN EN ISO12058-1:2018-11.

[0060] A suitable compound (C3-2) is selected from compounds in which at least one hydroxyl group, preferably both hydroxyl groups, is directly bonded to at least one aromatic moiety. Particularly preferably, the compound (C3-2) is selected from bisphenol A.

[0061] To facilitate the reaction between compounds (C3-1) and (C3-2), it is advantageous to use at least one catalyst. A particularly preferred catalyst is triphenylphosphine.

[0062] The product obtained by reacting compounds (C3-1) and (C3-2) preferably has an epoxy equivalent weight (EEW) of 800 - 2,000 g / equivalent, more preferably 900 - 1,500 g / equivalent, very preferably 980 - 1,100 g / equivalent, determined in accordance with DIN EN ISO3001:1999-11.

[0063] Compounds (C3-1), (C3-2) and (C3-3) may be reacted in a molar ratio of 10:6:1 to 7:4:1.

[0064] At least one solvent S2 present during the reaction of compound (C3-1) and (C3-2) may be selected from aliphatic and / or aromatic hydrocarbons, ketones, esters, alcohols, amides, methylal, butyral, 1,3-dioxolane, glycerol formal and mixtures thereof, preferably alcohols, very preferably phenoxypropanol and / or isobutanol.

[0065] The polyamine (C3-3) has an amine equivalent of 120 to 130 g / equivalent. The amine equivalent can be determined, for example, as described in the Examples section. The term "polyamine" refers to a compound containing at least two primary amine groups and at least one secondary amine group in the context of the present invention. The amine groups may be present as free amine groups or in a blocked form. A blocked amino group is one in which the hydrogen residue on the nitrogen present in the free amino group is substituted by reaction with a blocking agent, as is known. Such a blocked amino group can no longer participate in condensation or addition reactions possible with free amino groups. These reactions become possible only after removing the blocking agent to generate free amino groups. Thus, this principle is similar to the principle of capped or blocked isocyanates, which is also known in the field of polymer chemistry.

[0066] Particularly preferably, the polyamine (C3-3) is obtained by reacting the polyamine (A) with at least one blocking agent (BA). Particularly preferably, the primary amino groups of the polyamine are blocked with at least one blocking agent known per se, such as a ketone and / or an aldehyde. Reacting the primary amine with such a blocking agent produces a ketimine and / or an aldimine with the release of water. The said ketimine and / or aldimine no longer contain any nitrogen-hydrogen bonds, which means that typical condensation reactions or addition reactions of the amino group with further functional groups, such as isocyanate groups, do not occur.

[0067] The reaction conditions for preparing this type of blocked primary amine, for example, a ketimine, are known. Thus, by way of example, such blocking may be carried out by introducing heat into a mixture of the primary amine and an excess of ketone that functions simultaneously as a solvent for the amine. The water of the formed reaction is preferably removed during the reaction to prevent the possibility of the reverse reaction (debocking) of the reversible blocking from occurring. The reaction conditions for the debocking of the blocked primary amino groups are also known per se. For example, simply transferring the blocked amine into the aqueous phase is sufficient to shift the equilibrium back to the debocking side as a result of the concentration pressure exerted by the water, whereby free primary amino groups and free ketone are produced with the consumption of water.

[0068] Suitable blocking agents (BA) may be selected from acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, cyclohexanone or mixtures thereof, preferably methyl ethyl ketone and / or methyl isobutyl ketone. Preferred blocking agents are ketones, and in particular such ketones can be used as solvents for the reaction products of compounds (C3-1) and (C3-2). It has already been shown above that the preparation of the corresponding primary amines blocked with ketones proceeds with particularly good results with excess ketone. Thus, by using a ketone for blocking, it is possible to use the corresponding preferred preparation procedure for the blocked amines without the need for the inconvenient removal of costly residual blocking agents. Instead, the solution obtained during the preparation of polyamine (C3-3) can be used directly for the preparation of compound (C3) without removing the residual blocking agent (BA) present in the polyamine solution (C3-3).

[0069] Furthermore, the blocking with ketones and / or aldehydes, more specifically the preferred blocking with ketones, and the associated preparation of ketimines and / or aldimines has the advantage that the primary amino groups are selectively blocked. The secondary amino groups present are clearly not blocked and thus remain free. As a result, a polyamine (C3-C) containing not only two blocked primary amino groups but also one or two free secondary amino groups can be easily prepared from the corresponding polyamine (A) containing free secondary and primary amino groups by the aforementioned preferred blocking reaction.

[0070] Polyamine (C3-3) may be prepared by blocking the primary amino groups of polyamine (A) containing two primary amino groups and at least one secondary amino group. Ultimately preferred are any aliphatic, aromatic, or araliphatic (mixed aliphatic-aromatic) polyamines (A) known per se and having two primary amino groups and at least one secondary amino group. This means that not only the described amino groups, but also aliphatic, aromatic, or araliphatic groups themselves may be present. For example, a monovalent group located as a terminal group of the secondary amino group or a divalent group located between two amino groups is possible. The term "aliphatic" in the context of the present invention refers to any organic group that is not aromatic. For example, a group that is present in the same manner as the described amino groups may be an aliphatic hydrocarbon group, in other words, a group consisting only of carbon and hydrogen and not being aromatic. These aliphatic hydrocarbon groups may be linear, branched, or cyclic and may be saturated or unsaturated. These groups may, of course, include both cyclic and linear or branched moieties. It is also possible for the aliphatic group to contain heteroatoms, more specifically, in the form of crosslinking groups such as ether groups, ester groups, amide groups, and / or urethane groups. The possible aromatic groups are similarly known and no further explanation is necessary.

[0071] Preferably, polyamine (C3-3) has three or four amino groups, and these groups are selected from the group consisting of blocked primary amino groups and free secondary amino groups. A particularly preferred polyamine (C3-3) is one consisting of two blocked primary amino groups, one secondary amino group, and an aliphatic saturated hydrocarbon group. The term "blocked primary amino group" is used in the present invention when at least 95 mol% of any primary amino groups present in polyamine (A) are blocked by reaction with the above-mentioned blocking agent (BA) (determinable by IR spectroscopy; see the Examples section).

[0072] Examples of preferred polyamines (A) from which polyamines (C3-3) can be prepared by blocking primary amino groups are diethylenetriamine, 3-(2-aminoethyl)aminopropylamine, dipropylenetriamine, N1-(2-(4-(2-aminoethyl)piperazin-1-yl)ethyl)ethane-1,2-diamine (one secondary amino group, two primary amino groups for blocking), triethylenetetramine, N,N'-bis(3-aminopropyl)ethylenediamine (two secondary amino groups, two primary amino groups for blocking) and mixtures thereof, very preferably from diethylenetriamine.

[0073] As described above, polyamine (C3-3) is reacted with the product obtained from the reaction of compounds (C3-1) and (C3-2) (hereinafter referred to as product (C3-1 / 2)). Thus, the preparation of compound (C3) involves the reaction of product (C3-1 / 2) with polyamine (C3-3) by an addition reaction between the epoxide group of product (C3-1 / 2) and the free secondary amino group of polyamine (C3-3). This reaction is known per se, and subsequently, by ring-opening of the epoxide group from compound (C3), polyamine (C3-3) binds to polymer (C3-1 / 2). Thus, it will be readily apparent that in the preparation of compound (C3), it is preferred not to use any other amines having free or blocked primary or secondary amino groups. Compound (C3) can be prepared by established techniques known in bulk or in solution, particularly preferably by reaction of (C3-1 / 2) and (C3-3) in an organic solvent. Said solvent is selected from commonly used organic solvents, preferably from isobutanol and methyl isobutyl ketone.

[0074] Aqueous dispersion (AD): After reacting the aqueous dispersion of intermediate (I1) with compound (C3), the resulting dispersion can be diluted with an aqueous solution (step (c)). Said aqueous solution can contain at least one acid and / or auxiliary agent, for example typical emulsifiers and protective colloids.

[0075] At least one acid present in step (a) and / or (b) and / or (c) is preferably selected from organic acids. Suitable organic acids are, for example, carboxylic acids, sulfonic acids and phosphonic acids. Preferably, carboxylic acids are used. Examples of suitable carboxylic acids include lactic acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, malic acid, and tartaric acid. Particularly preferably, acetic acid is used in step (a) and / or (b) and / or (c).

[0076] Furthermore, the organic solvent present in the aqueous dispersion (AD) can be at least partially removed. The removal of at least one organic solvent can be carried out by any known method, for example, by vacuum distillation at a temperature slightly above room temperature, for example, 30 - 60 °C.

[0077] The cationic polymer particles present in the aqueous dispersion (AD) preferably have an average particle size (z-average) of 100 - 1,000 nm, more preferably 100 - 700 nm, even more preferably 100 - 600 nm, and very preferably 100 - 400 nm, determined in accordance with DIN EN ISO22412:2018-09.

[0078] The proportion of the cationic polymer particles in the aqueous dispersion (AD) is preferably 15 - 40% by mass, very preferably 20 - 30% by mass, in each case relative to the total mass of the aqueous dispersion (AD). This proportion can be determined, for example, via the solids content of the aqueous dispersion (AD) as described in the Examples section.

[0079] The total amount of water in the aqueous dispersion is preferably 60 - 85% by mass, very preferably 70 - 80% by mass, in each case relative to the total mass of the aqueous dispersion (AD).

[0080] The total proportion of the cationic polymer particles and water in the aqueous dispersion (AD) is preferably at least 90% by mass, preferably at least 95% by mass, and very preferably at least 98% by mass, in each case relative to the total mass of the aqueous dispersion. The proportion of the cationic polymer particles and water can be determined by summing the amount of the particles (e.g., determined by the solid content as described above) and the amount of water. Despite the low proportion of further components such as organic solvents, the aqueous dispersion (AD) exhibits high storage stability. Furthermore, since the amount of the solvent present in the dispersion (AD) is small, an additional fraction of the organic solvent required for formulating the electrodeposition coating material can be added without significantly increasing the overall VOC of the aqueous electrodeposition coating material.

[0081] The method of the present invention for producing an aqueous dispersion A further aspect of the present invention is a method for preparing an aqueous dispersion (AD) containing cationic polymer particles, said method comprising the following steps: (1) Preparing an aqueous dispersion of the intermediate (I1) by reacting a compound (C1) containing at least one free isocyanate group and at least two epoxide groups with (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and subsequently dispersing the intermediate (I1) in water by a process, (2) Reacting the aqueous dispersion of the intermediate (I1) obtained in step (1) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups, (3) Optionally, diluting the aqueous dispersion with an aqueous solution, and (4) Optionally, at least partially removing the organic solvent present in the dispersion obtained after step (3), comprising, at least one acid is present in step (1) and / or step (2) and / or step (3).

[0082] Regarding the compounds used in the method of the present invention and the preferred embodiments of the steps carried out by the method of the present invention, the aqueous dispersion (AD) of the present invention is referred to. Therefore, what has been described about the aqueous dispersion of the present invention is also applied mutatis mutandis to further preferred embodiments of the method of the present invention.

[0083] The aqueous electrocoating composition of the present invention: The aqueous dispersion (AD) of the present invention is used in the preparation of an aqueous electrocoating material. Thus, a further aspect of the present invention is an aqueous electrocoating material (ECM), which comprises the following components, (A) At least one aqueous dispersion (AD) of the present invention, or at least one aqueous dispersion (AD) prepared by the method of the present invention, (B) At least one further binder B different from the cationic polymer particles contained in the aqueous dispersion (AD), (C) Optionally at least one crosslinking agent (CL), (D) At least one pigment, (E) Optionally at least one additive, and (F) Optionally at least one catalyst and contains.

[0084] "Aqueous electrocoating material (ECM)" in the context of the present invention preferably means that the electrocoating material contains a proportion of water of at least 20% by mass, preferably at least 25% by mass, very preferably at least 50% by mass, in each case relative to the total amount of solvents (i.e., water and organic solvents) present. The proportion of water is preferably 70 - 100% by mass, more specifically 75 - 100% by mass, very preferably 80 - 100% by mass, in each case relative to the total amount of solvents present.

[0085] Aqueous dispersion (AD): The electrodeposition coating material preferably contains the above-mentioned aqueous dispersion (AD) in a total amount of 0.5 to 20% by mass, more preferably 1 to 15% by mass, even more preferably 1.5 to 10% by mass, and very preferably 2 to 4% by mass, in each case based on the total mass of the aqueous electrodeposition coating material (ECM).

[0086] Binder B, which is different from the cationic particles in the aqueous dispersion (AD): The term "binder", in the context of the present invention and in accordance with DIN EN ISO 4618 (German version, date: March 2007), preferably refers to the non-volatile fraction of the composition of the present invention involved in film formation (excluding any pigments and fillers in the composition), and more specifically, to the polymer resin involved in film formation. The non-volatile fraction may be determined by the method described in the Examples section.

[0087] Binder B may be self-crosslinkable and / or externally crosslinkable. The self-crosslinkable binder B contains reactive functional groups that can undergo a crosslinking reaction by heat with itself and / or complementary reactive functional groups in the self-crosslinkable binder B. In contrast, the externally crosslinkable binder B contains reactive functional groups that can undergo a crosslinking reaction by heat with complementary reactive functional groups in the crosslinking agent CL. Suitable reactive functional groups for the externally crosslinkable binder B are hydroxyl groups, thiol groups, and primary and secondary amino groups, especially hydroxyl groups. Suitable complementary reactive functional groups present in the crosslinking agent CL or, in the case of a self-crosslinkable binder, in binder B are blocked isocyanate groups, hydroxymethylene groups, and alkoxymethylene groups, preferably methoxymethylene groups and butoxymethylene groups, and especially methoxymethylene groups. The use of an externally crosslinkable binder having a hydroxyl group is preferred.

[0088] The amount of at least one binder B in the electrocoating material of the present invention is particularly guided by its solubility and its dispersibility in an aqueous medium, and its functionality regarding its crosslinking reaction with itself or a crosslinking agent CL, and can thus be easily determined by a person skilled in the art based on their general technical knowledge. Preferably, at least one binder B is present in a total amount of 50 to 90% by mass based on the solid content of the electrocoating material (ECM).

[0089] At least one binder B preferably contains latent cationic groups and / or cationic groups. Examples of suitable latent cationic groups that can be converted to cations by a neutralizing agent and / or a quaternizing agent are primary, secondary or tertiary amino groups, secondary sulfide groups or tertiary phosphine groups, especially tertiary amino groups or secondary sulfide groups. Examples of suitable cationic groups are primary, secondary, tertiary or quaternary ammonium groups, tertiary sulfonium groups or quaternary phosphonium groups, preferably quaternary ammonium groups or tertiary sulfonium groups, especially quaternary ammonium groups. Examples of suitable neutralizing agents for latent cationic groups are inorganic and organic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, lactic acid, dimethylolpropionic acid or citric acid, especially formic acid, acetic acid or lactic acid.

[0090] Examples of suitable binders B containing latent cationic groups or cationic groups are resins containing primary, secondary, tertiary or quaternary amino groups or ammonium groups and / or tertiary sulfonium groups, and preferably having an amine value between 20 and 250 mg KOH / g and a mass average molecular weight between 300 and 10,000 daltons. In particular, amino (meth)acrylate resins, amino epoxy resins, amino epoxy resins having terminal double bonds, amino epoxy resins having primary and / or secondary hydroxyl groups, amino polyurethane resins, amino-containing polybutadiene resins or modified epoxy resin-carbon dioxide-amine reaction products are used.

[0091] Alternatively, binder B may contain an anionic group and / or a latent anionic group. Examples of suitable latent anionic groups that can be converted to anions by a neutralizing agent are carboxylic acid groups, sulfonic acid groups or phosphonic acid groups, especially carboxylic acid groups. Examples of suitable anionic groups are carboxylate groups, sulfonate groups or phosphonate groups, especially carboxylate groups. Examples of suitable neutralizing agents for latent anionic groups are, for example, ammonia, ammonium salts such as ammonium carbonate or ammonium hydrogen carbonate, and amines such as trimethylamine, triethylamine, tributylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, diethylethanolamine, methyldiethanolamine, triethanolamine and the like.

[0092] The amount of the neutralizing agent is generally selected such that 1 to 100 equivalents, preferably 50 to 90 equivalents, of the latent cationic groups or latent anionic groups of binder B are neutralized.

[0093] Examples of suitable binder B1 for anion-precipitable electrodeposition coating materials are known from German Patent Application DE2824418A1. They are preferably polyester, epoxy resin ester, poly(meth)acrylate, maleate oil or polybutadiene oil, having a mass average molecular weight of 300 to 10,000 daltons and an acid value of 35 to 300 mg KOH / g.

[0094] Particularly preferred aqueous coating materials (ECM) are cathodically precipitable and thus contain at least one binder (B) having the above-mentioned cationic groups.

[0095] Any crosslinking agent CL The aqueous electrocoating material (ECM) of the present invention may contain at least one crosslinking agent CL as component (b). Preferably, at least one externally crosslinkable binder B is used in combination with at least one crosslinking agent CL. Particularly preferably, at least one externally crosslinkable binder B containing a latent cationic group or a cationic group is used in combination with at least one crosslinking agent CL.

[0096] Suitable crosslinking agents CL include all conventional and known crosslinking agents containing suitable complementary reactive functional groups. The crosslinking agent CL is preferably selected from the group consisting of blocked polyisocyanates, melamine-formaldehyde resins, tris(alkoxycarbonylamino)triazines, and polyepoxides. The crosslinking agent CL is more preferably selected from the group consisting of blocked polyisocyanates and highly reactive melamine-formaldehyde resins. Particularly preferably, a blocked polyisocyanate is used.

[0097] The blocked polyisocyanate CA can be prepared from conventional and known polyisocyanates containing isocyanate groups bonded to aliphatic, alicyclic, araliphatic and / or aromatic groups. It is preferred to use a polyisocyanate having 2 to 5 isocyanate groups per molecule and having a viscosity of 100 to 10,000 mPa·s, preferably 100 to 5,000 mPa·s, and particularly 100 to 2,000 mPa·s (23°C). Furthermore, the polyisocyanate may be modified to be hydrophilic or hydrophobic.

[0098] Suitable polyisocyanates include aliphatic polyisocyanates, aromatic polyisocyanates or mixtures of aromatic polyisocyanates and aliphatic polyisocyanates. Here, not only monomeric polyisocyanates, dimers or trimers of polyisocyanates, but also oligomeric polyisocyanates or polymeric polyisocyanates can be used. Preferred isocyanates are those whose monomeric constituents contain from about 3 to about 36, more specifically from about 8 to about 15 carbon atoms. Examples of such suitable monomeric polyisocyanates are diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethyl ethylene diisocyanate, methyl trimethylene diisocyanate, trimethyl hexamethylene diisocyanate, xylylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and 4,4'-diisocyanatodicyclohexylmethane. Polyisocyanates with a higher isocyanate functionality, such as tris(4-isocyanatophenyl)methane, 2,4,4'-triisocyanatodiphenylmethane, or bis(2,5-diisocyanato-4-methylphenyl)methane can also be used. These polyisocyanates may be used in the form of dimers or trimers, or can also serve as building blocks for oligomeric polyisocyanates or polymeric polyisocyanates. Furthermore, mixtures of polyisocyanates can also be utilized.

[0099] Examples of suitable blocking agents for the preparation of blocked polyisocyanate CA are as follows: - Phenols, such as phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, tert-butylphenol, hydroxybenzoic acid, esters of this acid or 2,5-di-tert-butyl-4-hydroxytoluene, - Lactams, such as ε-caprolactam, δ-valerolactam, γ-butyrolactam or β-propiolactam, - Active methylene compounds, such as diethyl malonate, dimethyl malonate, methyl or ethyl acetoacetate or acetylacetone, - Alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, n-amyl alcohol, tert-amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, methoxymethanol, glycolic acid, glycol esters, lactic acid, lactic acid esters, methylol urea, methylol melamine, diacetone alcohol, ethylene chlorohydrin, ethylene bromohydrin, 1,3-dichloro-2-propanol, acetocyanohydrin, 1,4-cyclohexyl-dimethanol or propanediol, - Mercaptans, such as butyl mercaptan, hexyl mercaptan, tert-butyl mercaptan, tert-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol or ethylthiophenol, - Acid amides, such as acetanilide, acetanisidine amide, acrylamide, methacrylamide, acetamide, stearamide or benzamide, - Imides, such as succinimide, phthalimide or maleimide, - Amines, such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine or butylphenylamine, - Imidazole, such as imidazole or 2-ethylimidazole, - Urea, such as urea, thiourea, ethyleneurea, ethylenethiourea or 1,3-diphenylurea, - Carbamate, such as phenyl N-phenylcarbamate or 2-oxazolidone, - Imine, such as ethyleneimine, - Oxime, such as acetone oxime, formaldehyde oxime, acetal oxime, acetoxy oxime, methyl ethyl ketoxime, diisobutyl ketoxime, diacetyl monoxime, benzophenone oxime or chlorohexanone oxime, - Sulfite salts, such as sodium bisulfite or potassium bisulfite, - Hydroxamic acid esters, such as benzyl methacrylohydroxamate (BMH) or allyl methacrylohydroxamate, or - Substituted pyrazole, imidazole or triazole, and - 1,2-polyols, such as ethylene glycol, propylene glycol, and 1,2-butanediol, - 2-hydroxy esters, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and mixtures of these blocking agents BA.

[0100] The amount of the crosslinking agent CL in the electrodeposition coating material of the present invention is particularly guided by the functionality of these crosslinking agents regarding the crosslinking reaction with the cationic polymer particles present in the aqueous dispersion (AD) and the binder B described above, and thus can be easily determined by those skilled in the art based on their general technical knowledge. Preferably, at least one crosslinking agent CL is present in a total amount of 15 to 30% by mass based on the total solid content of the electrodeposition coating material (ECM).

[0101] Pigment The aqueous electrocoating material (ECM) of the present invention further contains at least one pigment. The pigment is preferably selected from the group consisting of conventional and known coloring pigments, effect pigments, conductive pigments, magnetic shielding pigments, fluorescent pigments, extender pigments, and anticorrosive pigments. The total amount of the content is preferably in the range of 0.1 to 30% by mass, or in the range of 0.5 to 20% by mass, more preferably in the range of 1.0 to 15% by mass, very preferably in the range of 1.5 to 10% by mass, and more specifically in the range of 2 to 5% by mass, or in the range of 2 to 4% by mass, or in the range of 2 to 3.5% by mass, based on the total mass of the aqueous electrocoating material (ECM) in each case.

[0102] Additive: The electrodeposition coating material (ECM) of the present invention may further contain at least one conventional additive. The expression "additive" defines the presence of substances as molecularly independent units in the aqueous electrodeposition coating material (ECM), and in particular not as components reactively incorporated into binders, resins, etc. Suitable additives include fillers such as calcium sulfate, barium sulfate, silicates such as talc or kaolin, silica, oxides such as aluminum hydroxide or magnesium hydroxide, nanoparticles, organic fillers such as textile fibers, cellulose fibers, polyethylene fibers or wood flour, free radical scavengers, slip additives, polymerization inhibitors, defoamers, emulsifiers, especially non-ionic emulsifiers such as alkoxylated alkanols and polyols, phenols and alkylphenols or anionic emulsifiers such as alkoxylated alkanols and polyols, phenols and alkylphenols of alkancarboxylic acids, alkanesulfonic acids and sulfonic acids of alkali metal salts or ammonium salts, wetting agents such as siloxanes, fluorine compounds, carboxylic acid monoesters, phosphate esters, polyacrylic acid and its copolymers, or polyurethanes, adhesion promoters, leveling agents, film-forming aids such as cellulose derivatives, flame retardants, organic solvents, low molecular weight, oligomers and high molecular weight reactive diluents that can participate in thermal crosslinking, especially polyols such as tricyclodecane dimethanol, dendrimer polyols, highly branched polyesters, metathesis oligomers or polyols based on branched alkanes having more than 8 carbon atoms in the molecule, anti-cratering agents, polyvinyl alcohol polymers and mixtures thereof. The total amount of the additive is preferably 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, very preferably 0.1 to 10% by mass, particularly preferably 0.1 to 5% by mass, and more specifically 0.1 to 2.5% by mass based on the total mass of the aqueous electrodeposition coating material (ECM).

[0103] Catalyst: The electrodeposition coating material (ECM) of the present invention may further contain at least one crosslinking catalyst. Suitable catalysts are organic and inorganic salts and complexes of tin, lead, antimony, bismuth, iron or manganese, preferably inorganic and organic salts, and complexes of bismuth and tin. Preferred tin catalysts are selected from dibutyltin oxide or dibutyltin dilaurate.

[0104] Preferred inorganic salts of bismuth include bismuth nitrite.

[0105] Preferred organic salts and complexes of bismuth are selected from bismuth subsalicylate, bismuth lactate, bismuth ethylhexanoate and bismuth dimethylolpropionate. Particularly preferably, bismuth subsalicylate (C7H5O4Bi) or bismuth subsitrate is used as the crosslinking catalyst.

[0106] The electrodeposition coating material of the present invention preferably contains a total amount of catalyst, particularly bismuth subsalicylate, of 0.05 to 5% by mass, more preferably 0.1 to 4% by mass, and particularly 0.2 to 4% by mass, based on its solid content.

[0107] Preparation of Aqueous Electrodeposition Coating (ECM) The electrodeposition coating material of the present invention is prepared by mixing and homogenizing the above-described constituent components (A), (B), and (D), and optionally (C), (E), and (F) using conventional and known mixing techniques and apparatuses, such as stirring tanks, stirring mills, extruders, kneading apparatuses, Ultra Turrax (registered trademark), in-line dissolvers, static mixers, micromixers, gear-type dispersers, pressure relief nozzles, and / or microfluidizers. Particularly preferably, the aqueous dispersion (AD) is mixed with the binder B and optionally the crosslinking agent CL, and then the pigment paste and further additives are added. The pigment and the bismuth-containing catalyst are preferably incorporated into the electrodeposition coating material in the form of a pigment paste or a pigment preparation (see Roempp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998, "Pigment preparations", page 452).

[0108] What has been described above regarding the aqueous dispersion (AD) of the present invention and the method of the present invention for producing the aqueous dispersion (AD) also applies mutatis mutandis to further preferred embodiments of the aqueous electrodeposition coating composition of the present invention.

[0109] Method of the present invention for producing a substrate at least partially coated: The aqueous electrodeposition coating material (ECM) of the present invention can be used to at least partially coat a conductive substrate, such as a metal substrate. The conductive substrate preferably includes an automotive vehicle or a part thereof.

[0110] Therefore, a further subject of the present invention is a method for producing a substrate at least partially coated by bringing the substrate into contact with the aqueous electrodeposition coating material of the present invention, forming a film from the said material, and curing the formed film. This method can further include rinsing the formed film and applying at least one further coating layer onto the cured electrodeposition coating material.

[0111] Step (a): In step (a) of the method of the present invention, the substrate is brought into at least partial contact with the aqueous electrocoating material (ECM) of the present invention. "Contact" in the sense of the present invention means applying the aqueous electrocoating material to the substrate. The application of the electrocoating material (ECM) to the substrate or the formation of a coating film on the substrate is understood as follows: The electrocoating material (ECM) is applied such that a coating film formed from the material is disposed on the substrate, but it is not necessarily in direct contact with the substrate. Thus, other layers can be present between the coating film and the substrate. For example, a conversion coating, such as a zinc phosphate coating, may be disposed between the substrate and the cured electrocoating layer. This application can be achieved, for example, by immersing the substrate in the aqueous electrocoating material or by spraying or roll-applying the material onto the substrate. Preferably, the application is achieved by immersing the substrate in the material.

[0112] Preferably, the coating of the substrate in step (a) is carried out by electrophoretic, preferably cataphoretic, deposition of this coating material onto the substrate surface. This is preferably achieved by introducing the substrate at least partially, preferably completely, into an immersion coating bath containing the electrocoating material (ECM) of the present invention and applying a voltage between the substrate and at least one counter electrode. In this case, the counter electrode may be disposed in the immersion coating bath. Alternatively or additionally, the counter electrode may be present separately from the immersion coating bath, for example, via an anion-exchange membrane permeable to anions. In this case, the anions formed in the immersion coating are transported through the membrane from the coating material into the anolyte, making it possible to adjust or maintain the pH of the immersion coating bath. The counter electrode is preferably separate from the immersion coating bath. The passage of current between the anode and the cathode is accompanied by the deposition of a firmly adhering coating film on the cathode, i.e., on the substrate.

[0113] Step (a) of the method of the present invention is preferably carried out at a temperature in the range of 25 to 35 °C and a voltage of 120 to 350 V, preferably 140 to 300 V. The voltage may be kept constant during the described period. However, alternatively, during the deposition period, the voltage may adopt different values within the range of the minimum and maximum values mentioned above, for example, going back and forth from the minimum to the maximum of the deposition voltage, or rising linearly or stepwise. In step (a) of the method of the present invention, preferably, a complete coating of the substrate with the aqueous electrocoating material (ECM) of the present invention is carried out by complete electrophoretic, preferably cataphoretic deposition over the entire surface of the substrate.

[0114] In step (a) of the method of the present invention, the aqueous electrocoating material (ECM) of the present invention is preferably applied such that the resulting cured electrocoating film has a dry film thickness in the range of 5 to 70 μm, more preferably 10 to 60 μm, and particularly preferably 20 to 50 μm.

[0115] Optional step (b): In step (b), the coating film formed in step (a) may be rinsed with an aqueous solution. In one embodiment, the aqueous solution mainly contains water, but may also contain a small amount of further additives. In another embodiment, the aqueous solution consists of an ultrafiltrate obtained from the aqueous electrocoating material (ECM). By carrying out optional step (b), the excess aqueous electrocoating material (ECM) on the at least partially coated substrate present after step (a) can be reused in the dip coating bath.

[0116] Step (c): In step (c) of the method of the present invention, after step (a) or (b), the coating film obtained by at least partially applying the aqueous electrocoating material (ECM) of the present invention on the substrate is cured.

[0117] The curing of an electrodeposited coating is understood to mean the conversion of such a coating into a state in which it can be used immediately, i.e., a state in which the substrate provided with each coating can be transported, stored, and used as intended. More specifically, the cured coating is no longer soft or sticky, but is adjusted as a solid coating film, and even when further exposed to the curing conditions, no further significant change occurs in its properties, such as hardness or adhesion to the substrate.

[0118] Step (c) of the method of the present invention is preferably carried out by baking, after step (a) or (b), preferably in an oven. Here, curing is preferably carried out at a substrate temperature in the range of 100 to 250 °C, more preferably 130 to 190 °C. Step (c) is preferably carried out over a duration of 10 to 30 minutes, more preferably 15 minutes.

[0119] Optional step (d): After curing the coating layer in step (c), at least one further coating layer may be applied onto the cured coating layer. The resulting electrodeposit coating can then be overcoated by wet-on-wet technology with a surfacer, or a stone chip resistant primer, and a clear topcoat material, or alternatively, with a basecoat material and a clearcoat material. The surfacer film or the stone chip resistant primer film and the clear topcoat film are preferably baked separately. The basecoat film and the clearcoat film are preferably baked together. By this procedure, a multi-coat paint system with outstanding performance characteristics is obtained.

[0120] What has been described about the aqueous dispersion (A) of the present invention, the method of the present invention for producing the aqueous dispersion (AD) of the present invention, and the aqueous electrodeposition coating composition (ECM) of the present invention also applies mutatis mutandis to further preferred embodiments of the method of the present invention for producing a substrate at least partially coated.

[0121] The coated substrate of the present invention: A further subject of the present invention is a conductive substrate that has been at least partially coated by the method of the present invention.

[0122] What has been described above regarding the aqueous dispersion (AD) of the present invention, the method of the present invention for producing the aqueous dispersion (AD), the aqueous electrocoating material (ECM) of the present invention, and the method of the present invention for producing a substrate that is at least partially coated also applies mutatis mutandis to further preferred embodiments of the coated substrate according to the present invention.

[0123] 1. An aqueous dispersion (AD) containing cationic polymer particles, wherein the aqueous dispersion (AD) a) preparing an aqueous dispersion of intermediate (I1) by reacting a compound (C1) containing at least one free isocyanate group and at least two epoxide groups with (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and then subsequently dispersing the intermediate (I1) in water by a process, b) reacting the aqueous dispersion of intermediate (I1) obtained in step (a) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups, c) optionally, diluting the aqueous dispersion with an aqueous solution, and d) optionally, at least partially removing the organic solvent present in the dispersion obtained in step (c), obtained by an aqueous dispersion in which at least one acid is present in step a) and / or step b) and / or step c).

[0124] 2. The aqueous dispersion according to clause 1, wherein the compound (C1) contains exactly one free isocyanate group and exactly two epoxide groups.

[0125] 3. An aqueous dispersion according to section 1 or 2, wherein the compound (C1) has an epoxy equivalent weight (EEW) of 300 to 700 g / equivalent, preferably 350 to 650 g / equivalent, more preferably 400 to 600 g / equivalent, even more preferably 450 to 550 g / equivalent, and very preferably 500 to 530 g / equivalent, determined in accordance with DIN EN ISO 3001:1999-11.

[0126] 4. An aqueous dispersion according to any of the preceding sections, wherein the compound (C1) is obtained by reacting at least one compound (C1-1) containing at least two epoxide groups, in particular at least three epoxide groups, with at least one compound (C1-2) containing at least one amine group, and further reacting the resulting product with at least one compound (C1-3) containing at least two free isocyanate groups.

[0127] 5. An aqueous dispersion according to section 4, wherein the compound (C1-1) is a reaction product of propoxylated pentaerythritol and epichlorohydrin.

[0128] 6. An aqueous dispersion according to section 4 or 5, wherein the compound (C1-2) is selected from secondary amines, preferably C1-C 10 dialkylamines, more preferably C2-C6 dialkylamines, and very preferably C3 dialkylamines.

[0129] 7. An aqueous dispersion according to any of sections 4 to 6, wherein the compound (C1-3) is selected from alicyclic, aliphatic-alicyclic, aromatic, aliphatic-aromatic and / or alicyclic-aromatic diisocyanates, dimers and trimers of the described diisocyanates, and mixtures thereof, preferably aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane 4,4'-diisocyanate, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, and m-tetramethylxylylene diisocyanate (m-TMXDI), and very preferably isophorone diisocyanate.

[0130] 8. An aqueous dispersion according to any one of paragraphs 4 to 7, wherein compounds (C1-1), (C1-2) and (C1-3) are reacted in a molar ratio of 1:5:5 to 1:1:1, preferably 1:3:3 to 1:1:1, very preferably 1:1:1.

[0131] 9. An aqueous dispersion according to any one of the preceding paragraphs, wherein the polyvinyl alcohol polymer is a copolymer of vinyl alcohol and at least one ethylenically unsaturated monomer preferably selected from vinyl acetate, vinyl acetal, ethylene and / or propylene.

[0132] 10. An aqueous dispersion according to any one of the preceding paragraphs, wherein the polyvinyl alcohol polymer has a vinyl alcohol fraction of 50 to 99.9 mol%, preferably 60 to 99.9 mol%, more preferably 70 to 99 mol%, very preferably 80 to 99 mol%.

[0133] 11. An aqueous dispersion according to any one of the preceding paragraphs, wherein the polyvinyl alcohol polymer has a viscosity at 20 °C of at least 2 mPa·s, preferably 2 to 60 mPa·s, more preferably 10 to 60 mPa·s, even more preferably 30 to 50 mPa·s, very preferably 45 to 49 mPa·s, determined at a concentration of 4% by mass in water in accordance with DIN 53015:2018-07.

[0134] 12. An aqueous dispersion according to any one of the preceding paragraphs, wherein the polyvinyl alcohol polymer has a degree of hydrolysis of 70 to 100 mol%, preferably 70 to 95 mol%, very preferably 86 to 89 mol%.

[0135] 13. An aqueous dispersion according to any one of the preceding paragraphs, wherein the aqueous solution (C2a-i) contains 5 to 15% by mass of the polyvinyl alcohol polymer, preferably 5 to 10% by mass of the polyvinyl alcohol polymer, and 85 to 95% by mass, preferably 90 to 95% by mass of water, in each case based on the total mass of the aqueous solution (C2a-i).

[0136] 14. An aqueous dispersion according to any of the preceding paragraphs, wherein compound (C1) is reacted with compound (C2a-i) in a ratio of 1:10 to 10:1, preferably 1:10 to 2:1, very preferably 1:10 to 1:1, each ratio being based on the solids content of compounds (C1) and (C2a-i).

[0137] 15. An aqueous dispersion according to any of paragraphs 1 to 12, wherein dispersion (C2a-ii) contains 50 to 60% by mass of a polyvinyl alcohol polymer and 40 to 50% by mass of at least one organic solvent S1, in each case based on the total mass of dispersion (C2a-ii).

[0138] 16. An aqueous dispersion according to paragraph 15, wherein organic solvent S1 is selected from aliphatic and / or aromatic hydrocarbons, ketones, esters, amides, methylal, butyral, 1,3-dioxolane, glycerol formal, hydrocarbons and mixtures thereof, preferably ketones, very preferably methyl isobutyl ketone.

[0139] 17. An aqueous dispersion according to any of paragraphs 1 to 12 and 15 to 16, wherein compound (C1) is reacted with compound (C2a-ii) in a mass ratio of 1:20 to 1:10, preferably 1:17 to 1:15.

[0140] 18. An aqueous dispersion according to any of the preceding paragraphs, wherein at least one compound (C3-1) containing at least one epoxide group is reacted with at least one compound (C3-2) containing at least one aromatic group and at least two hydroxyl groups in the presence of at least one solvent S2, and the resulting product is further reacted with at least one polyamine (C3-3) containing at least two blocked primary amino groups and at least one free secondary amino group to obtain compound (C3).

[0141] 19. An aqueous dispersion according to paragraph 18, wherein compound (C3-1) is reacted with compound (C3-2) in the presence of at least one catalyst, in particular triphenylphosphine.

[0142] 20. An aqueous dispersion according to section 18 or 19, wherein the product obtained by reacting compounds (C3-1) and (C3-2) has an epoxy equivalent weight (EEW) of 800 to 2,000 g / equivalent, preferably 900 to 1,500 g / equivalent, and very preferably 980 to 1,100 g / equivalent, determined in accordance with DIN EN ISO3001:1999-11.

[0143] 21. An aqueous dispersion according to any of sections 19 to 20, wherein compounds (C3-1), (C3-2) and (C3-3) are reacted in a molar ratio of 10:6:1 to 7:4:1.

[0144] 22. An aqueous dispersion according to any of sections 18 to 21, wherein compound (C3-1) has an epoxy equivalent weight (EEW) of 100 to 300 g / equivalent, preferably 150 to 250 g / equivalent, and very preferably 170 to 200 g / equivalent, determined in accordance with DIN EN ISO3001:1999-11.

[0145] 23. An aqueous dispersion according to any of sections 18 to 22, wherein compound (C3-1) has a viscosity at 20 °C of 30,000 to 50,000 mPa*s, preferably 35,000 to 37,000 mPa*s, determined in accordance with DIN EN ISO12058-1:2018-11.

[0146] 24. An aqueous dispersion according to any of sections 18 to 23, wherein compound (C3-2) is selected from compounds in which at least one hydroxyl group, preferably both hydroxyl groups, is directly bonded to at least one aromatic moiety.

[0147] 25. An aqueous dispersion according to any of sections 18 to 24, wherein compound (C3-2) is selected from bisphenol A.

[0148] 26. An aqueous dispersion according to any of paragraphs 18 to 25, wherein at least one solvent S2 is selected from aliphatic and / or aromatic hydrocarbons, ketones, esters, alcohols, amides, methylal, butyral, 1,3-dioxolane, glycerol formal, and mixtures thereof, preferably alcohols, very preferably phenoxypropanol and / or isobutanol.

[0149] 27. An aqueous dispersion according to any of paragraphs 18 to 26, wherein the polyamine (C3-3) has an amine equivalent of 120 to 130 g / equivalent.

[0150] 28. An aqueous dispersion according to any of paragraphs 18 to 27, wherein the polyamine (C3-3) is obtained by reacting a polyamine (A) with at least one blocking agent (BA).

[0151] 29. An aqueous dispersion according to paragraph 28, wherein the polyamine (A) is selected from diethylenetriamine, 3-(2-aminoethyl)aminopropylamine, dipropylenetriamine, N1-(2-(4-(2-aminoethyl)piperazin-1-yl)ethyl)ethane-1,2-diamine, triethylenetetramine, N,N'-bis(3-aminopropyl)ethylenediamine, and mixtures thereof, preferably diethylenetriamine.

[0152] 30. An aqueous dispersion according to paragraph 28 or 29, wherein at least one blocking agent (BA) is selected from acetone, methyl ethyl ketone, methyl isobutyl ketone, diisopropyl ketone, cyclopentanone, cyclohexanone, and mixtures thereof, preferably methyl ethyl ketone and / or methyl isobutyl ketone.

[0153] 31. An aqueous dispersion according to any of the preceding paragraphs, wherein at least one acid is selected from organic acids, preferably carboxylic acids, very preferably acetic acid.

[0154] 32. An aqueous dispersion according to any of the preceding paragraphs, wherein the polymer particles have an average particle size (z-average) of 100 to 1,000 nm, preferably 100 to 700 nm, more preferably 100 to 600 nm, and very preferably 100 to 400 nm, determined in accordance with DIN EN ISO 22412:2018-09.

[0155] 33. An aqueous dispersion according to any of the preceding paragraphs, wherein the aqueous dispersion (AD) contains cationic polymer particles in a total amount of 15 to 40% by mass, preferably 20 to 30% by mass, in each case based on the total mass of the aqueous dispersion (AD).

[0156] 34. An aqueous dispersion according to any of the preceding paragraphs, wherein the aqueous dispersion (AD) contains water in a total amount of 60 to 85% by mass, preferably 70 to 80% by mass, in each case based on the total mass of the aqueous dispersion (AD).

[0157] 35. An aqueous dispersion according to any of the preceding paragraphs, wherein the total proportion of the cationic polymer particles and water in the aqueous dispersion (AD) is at least 90% by mass, preferably at least 95% by mass, and very preferably at least 98% by mass, in each case based on the total mass of the aqueous dispersion.

[0158] 36. A method for preparing an aqueous dispersion (AD) containing cationic polymer particles, comprising the following steps: (1) Preparing an aqueous dispersion of intermediate (I1) by reacting a compound (C1) containing at least one free isocyanate group and at least two epoxide groups with (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and subsequently dispersing the intermediate (I1) in water in a step; (2) Reacting the aqueous dispersion of intermediate (I1) obtained in step (1) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups. (3) Optionally, a step of diluting the aqueous dispersion with an aqueous solution, and (4) Optionally, a step of at least partially removing the organic solvent present in the dispersion obtained after step (3), comprising a method in which at least one acid is present in step (1) and / or step (2) and / or step (3).

[0159] 37. The following components, (A) At least one aqueous dispersion (AD) according to any of sections 1 to 35, or at least one aqueous dispersion (AD) prepared by the method according to section 36, (B) At least one further binder B different from the cationic polymer particles contained in the aqueous dispersion (AD), (C) Optionally at least one crosslinking agent (CL), (D) At least one pigment, (E) Optionally at least one additive, and (F) Optionally at least one catalyst An aqueous electrocoating material (ECM) comprising

[0160] 38. The aqueous electrocoating material according to section 37, wherein at least one aqueous dispersion (AD) is present in a total amount of 0.5 to 20% by mass, preferably 1 to 15% by mass, more preferably 1.5 to 10% by mass, very preferably 2 to 4% by mass, in each case based on the total mass of the aqueous electrocoating material (ECM).

[0161] 39. A method for producing a substrate at least partially coated, comprising the following steps: (a) A step of bringing the substrate into at least partial contact with the aqueous electrocoating material (ECM) according to section 37 or 38, (b) Optionally, a step of rinsing the coating film formed in step (b) with an aqueous solution, (c) A step of curing the coating film formed after step (a) or after any step (b), and (d) Optionally, applying at least one additional coating layer and curing the coating layer A method comprising the steps of:

[0162] 40. A substrate at least partially coated by the method according to paragraph 39.

Examples

[0163] The present invention will be described in more detail by way of useful examples, but is in no way limited to these useful examples. Furthermore, in the examples, the terms "parts", "%", and "ratio" indicate "parts by mass", "% by mass", and "mass ratio", respectively, unless otherwise indicated.

[0164] 1. Method of measurement 1.1 Solids content (solids, non-volatile fraction) Unless otherwise stated, the solids content (also called the proportion of solids, the content in the solid state, or the proportion of non-volatile matter) was measured in accordance with DIN EN ISO 3251:2019-09 at 130 °C or 180 °C for 30 minutes, with the initial mass of the sample being 1.0 g.

[0165] 1.2 Epoxy equivalent The epoxy equivalent was measured in accordance with DIN EN ISO 3001:2019-08.

[0166] 1.3 Measurement of viscosity The viscosity of Compound C3 was measured at 23 °C at a shear rate of 5,000 s -1 or 10,000 s -1 using a Brookfield CAP000+ viscometer, cone and plate type, cone CAP03, in accordance with DIN EN ISO 3219:1994-10 and DIN 53019-2:2001-02.

[0167] 1.4. Amine equivalent mass The amine equivalent mass (solution) was confirmed as follows: The analytical sample was dissolved in glacial acetic acid at room temperature and titrated with 0.1 N perchloric acid in glacial acetic acid in the presence of crystal violet. From the initial mass of the sample and the consumption of perchloric acid, the amine equivalent mass (solution), that is, the mass of the basic amine solution required to neutralize 1 mole of perchloric acid, was determined.

[0168] 1.5. Degree of Blocking of Primary Amino Groups The degree of blocking of primary amino groups was measured by IR spectroscopic analysis using a Nexus FT IR spectrometer (manufactured by Nicolet), with the assistance of an IR cell (d = 25 μm, KBr window), at an absorption maximum of 3310 cm -1 using the concentration series of the amine used and based on the normalization of the absorption maximum (internal standard) at 1166 cm at 25 °C. -1 at 25 °C.

[0169] 1.6 Average Particle Size (z-Average) The average particle size (z-average) of the cationic particles contained in the aqueous dispersion (AD) was measured in accordance with DIN EN ISO 22412:2018-09.

[0170] 1.7 Salt Spray Test (SST) The corrosion resistance of the coating was measured by a salt spray test. The salt spray test was carried out in accordance with DIN EN ISO 9227 NSS (date: September 2012) for the coated substrate under investigation. The sample under investigation was continuously housed in a chamber at a temperature of 35 °C for 504 hours or 1008 hours, and a mist was generated from a 5% concentration sodium chloride solution with the pH controlled in the range of 6.5 to 7.2. The mist was deposited on the sample under investigation, and the sample was covered with a corrosive salt film.

[0171] Before the salt spray test in accordance with DIN EN ISO9227 NSS, if a cut is made with a blade through the coating of the sample to be investigated down to the substrate, the substrate will corrode along the cut line during the DIN EN ISO9227 NSS salt spray test, so that the sample can be investigated for the level of corrosive erosion of DIN EN ISO4628-8 (03-2013). As a result of the progress of corrosion, the coating is more or less eroded during the test. The degree of erosion (in mm) is an indicator showing the resistance of the coating to corrosion.

[0172] Furthermore, each of the evaluation results shown below is the average of three individual test results. Each individual test result was generated by an individual panel (i.e., the coated test substrate). If the individual panel presented seven individual holes, the individual test result itself of one individual panel regarding the edge protection of the holes is the analytical average of the seven individual holes.

[0173] 1.8 VDA climate change test The VDA climate change test is used to determine the corrosion resistance of the coating on the substrate and is carried out in accordance with DIN EN ISO11997-1:2018-01 (hereinafter referred to as VDA1) in 5 or 10 so-called cycles, or in accordance with VDA233-102 (June 2013) in 12 so-called cycles (hereinafter referred to as VDA2).

[0174] When the coating under test is present on a perforated metal substrate, these holes simulate a realistic metal substrate with a relatively large number of edges / edge zones. Also, for substrates with holes having edges that have not been post-treated, such as sanding or polishing, before starting any pre-treatment and coating process, these substrates are even more difficult in terms of coating and thus corrosion edge protection. The degree of corrosion of the edges of these holes (also called "corrosion of the hole edges" or "edge corrosion") is visually evaluated by observing the degree / portion of corrosion of the hole edges after a climate change test (on an evaluation scale from 0 to 5, where "5" means 100% corrosion (the entire edge of the hole is corroded) and "0" means 0% corrosion).

[0175] Before conducting the climate change test, if a cut is made with a knife through the coating of the sample under test down to the substrate, the substrate will corrode along the cut during the climate change test, so the degree of under-film corrosion of the sample can be tested in accordance with DIN EN ISO4628-8(03-2013). As corrosion progresses, the coating is more or less infiltrated during the test. The degree of erosion (in mm) serves as an indicator of the corrosion resistance of the coating (so-called scribing corrosivity).

[0176] Furthermore, each of the evaluation results shown below is the average of three individual test results. Each individual test result was generated by an individual panel (i.e., the coated test substrate). If an individual panel presented seven individual holes, the individual test result itself for one individual panel regarding edge protection of the holes is the analytical average of the seven individual holes.

[0177] 1.9 Surface roughness The surface roughness was measured in accordance with DIN EN10049:2014-03.

[0178] 1.10 Film build-up The film build-up was measured in accordance with DIN EN ISO2178:2016-11.

[0179] 2. Preparation of an Aqueous Dispersion (AD) of Cationic Polymer Particles 2.1 Preparation of Aqueous Dispersions (AD1) to (AD6) of the Cationic Polymer Particles of the Present Invention Using Solutions of Polyvinyl Alcohol Polymers 2.1.1 Preparation of Compound (C1) 33.6 parts of a liquid epoxy resin (epoxy equivalent weight (EEW) = 220 - 230 g / equivalent) was added to a reactor, and the contents of the reactor were heated to 50°C. Then, 5.1 parts of a dialkylamine was added with stirring, and stirring was continued at 50°C for an additional 1 hour until the epoxy equivalent weight (EEW) of the resulting reaction product (RP1) exceeded 380 g / equivalent.

[0180] In another reactor, 50 parts of methyl isobutyl ketone and 11.2 parts of isophorone diisocyanate were mixed, and the mixture was heated to 70°C with stirring. Then, the reaction product RP1 was added over 1.5 hours with stirring, and stirring was continued at 70°C for 1 hour to obtain a compound (C1) having an epoxy equivalent weight (EEW) in the range of 495 - 520 g / equivalent and a solid content of 49 - 50 mass%.

[0181] 2.1.2 Preparation of Various Aqueous Solutions (C2a - i) of Polyvinyl Alcohol Polymers Various aqueous solutions were prepared according to the following general procedure (see Table 1 for the amounts of polyvinyl alcohol polymer and water): Each amount of polyvinyl alcohol polymer (PVA) (commercially available under the trade name "Mowiol" from Kuraray Co., Ltd.) was slowly added to the first portion of water with vigorous stirring. Then, the solution was heated to 80°C, and the second portion of water was added. The resulting aqueous solution of the polyvinyl alcohol polymer was cooled to 20°C.

[0182]

Table 1

[0183] 2.1.3 Preparation of Various Aqueous Dispersions of Intermediate (I1) Various aqueous dispersions of intermediate (I1) were prepared according to the following general procedure (see Table 2 for amounts): Each amount of compound (C1) prepared as described in item 2.1.1 was dispersed in each amount of the aqueous polyvinyl alcohol polymer solution prepared as described in item 2.1.2 over 10 minutes with stirring at 20°C. After stirring was continued at 20°C for 30 minutes, each amount of acetic acid was added at 20°C over 5 minutes. After the addition was complete, stirring was continued for an additional 2 hours to obtain each intermediate (I1).

[0184]

Table 2

[0185] 2.1.4 Preparation of polyamine (C3-3) Polyamine (C3-3) was prepared from the reaction of diethylenetriamine (manufactured by BASF SE) and methyl isobutyl ketone by azeotropically removing water at 110 - 140°C in methyl isobutyl ketone. Adjusting the amine equivalent mass (solution) to 124 g / equivalent was done by dilution with methyl isobutyl ketone. Blocking of 98.5% of the primary amino groups was determined by IR spectroscopy based on the residual absorption at 3310 cm -1 as determined by IR spectroscopy based on the residual absorption at 3310 cm

[0186] 2.1.5 Preparation of compound (C3) 13.3 parts of a liquid epoxy resin (EEW = 184 - 189 g / equivalent), 6.1 parts of bisphenol A, and 2.2 parts of phenoxypropanol were mixed in a reactor and heated to 150°C, then 0.036 part of triphenylphosphine was added. The contents of the reactor were cooled to 130°C and stirring was continued until the EEW of the resulting reaction product exceeded 1,000 g / equivalent (if necessary, additional triphenylphosphine was added to obtain the EEW). Then, the mixture was diluted with 9.4 parts of isobutanol, cooled to 105°C, and 2.2 parts of polyamine (C3-3) prepared as described in item 2.1.4 was added over 30 minutes. The viscosity of the resulting compound (C3) (35% solution in methoxy - 2,1 - propanol) was 503 mPa*s.

[0187] 2.1.6 Preparation of various aqueous dispersions (AD1) to (AD6) Various aqueous dispersions (AD1) to (AD4) were prepared according to the following general procedure (see Table 3 for amounts): The amounts of the aqueous dispersions of intermediates (I1-1) to (I1-6) and acetic acid were added with stirring to 33.2% by mass of compound C3 prepared as in item 2.1.5. Finally, the mixture was diluted with each amount of water to obtain each aqueous dispersion (AD).

[0188] [Table 3]

[0189] 2.2 Preparation of an aqueous dispersion (AD7) of the cationic polymer particles of the present invention using a dispersion of a polyvinyl alcohol polymer in an organic solvent 2.2.1 Preparation of a dispersion (C2b-ii) of a polyvinyl alcohol polymer in an organic solvent A 60% by mass dispersion of a polyvinyl alcohol polymer in methyl isobutyl ketone was prepared by dispersing 300 grams of a polyvinyl alcohol polymer (commercially available under the trade name "Mowiol" from Kuraray Co., Ltd.) in 200 grams of methyl isobutyl ketone with vigorous stirring at 80°C.

[0190] 2.2.2 Preparation of an aqueous dispersion of intermediate (I1) 30 grams of compound (C1) prepared as in item 2.1.1 was added to 500 grams of the dispersion prepared in item 2.2.1 with stirring at 80°C over 30 minutes. After stirring was continued at 80°C for 3 hours, methyl isobutyl ketone was removed by evaporation. 125 grams of the resulting product was dispersed in 2375 grams of water with vigorous stirring at 20°C, and the temperature was raised to 80°C. Stirring was continued at 80°C for an additional 3 hours to obtain an aqueous dispersion of intermediate (I1).

[0191] 2.2.3 Preparation of compound (C3) 13.3 parts of liquid epoxy resin (EEW = 184 - 189 g / equivalent), 6.1 parts of bisphenol A, and 2.2 parts of phenoxypropanol were mixed in a reactor, heated to 150 °C, and then 0.036 part of triphenylphosphine was added. The contents of the reactor were cooled to 130 °C and stirring was continued until the EEW of the resulting reaction product exceeded 1,000 g / equivalent (additional triphenylphosphine was added if necessary to obtain the EEW). The mixture was then diluted with 9.4 parts of isobutanol, cooled to 105 °C, and 2.2 parts of polyamine (C3 - 3) prepared as in item 2.1.4 was added over 30 minutes. The viscosity of the resulting compound (C3) (35% solution in methoxy - 2,1 - propanol) was 473 mPa·s.

[0192] 2.2.4 Preparation of Aqueous Dispersion (AD7) A mixture of 22.0 parts of the aqueous dispersion of intermediate (I1) prepared as in item 2.2.2 and 0.379 part of acetic acid was added with stirring to 33.2 parts of compound C3 prepared as in item 2.2.3. Finally, the mixture was dispersed in 44.4 parts of water to obtain an aqueous dispersion having a solid content of 22.9% and an average particle size (z - average) of 321 nm.

[0193] 2.3 Preparation of Comparative Example of Aqueous Dispersion of Cationic Polymer Particles (AD - C) 13.3 parts of a liquid epoxy resin (EEW = 184 - 189 g / equivalent), 6.1 parts of bisphenol A, and 2.2 parts of phenoxypropanol were mixed in a reactor, heated to 150 °C, and then 0.036 part of triphenylphosphine was added. The contents of the reactor were cooled to 130 °C, and stirring was continued until the EEW of the resulting reaction product exceeded 1,000 g / equivalent. Then, the mixture was diluted with 3.7 parts of isobutanol, cooled to 105 °C, and 2.2 parts of polyamine (C3 - 3) prepared as in item 2.1.4 was added over 30 minutes. The resulting mixture was diluted with 5.4 parts of isobutanol and 22 parts of water. Then, 0.38 part of acetic acid was added, and the mixture was dispersed in 44.4 parts of water and 0.34 part of isobutanol to obtain an aqueous dispersion having an approximate solid content of 22% by mass and an average particle size (z - average) of approximately 100 nm.

[0194] 3. Preparation of an aqueous electrodeposition coating composition For testing as a cathodic electrodepositable coating material, an aqueous binder dispersion (BD), a pigment paste, each of the above aqueous dispersions (AD), and optionally an aqueous solution PVA - 1 of a polyvinyl alcohol polymer prepared as in item 2.1.2 were combined according to Table 4 below. The procedure here was to introduce the binder dispersion (BD) as an initial charge and dilute it with deionized water. Then, while stirring, each aqueous dispersion (AD) was added. Then, the pigment paste and the optional aqueous solution PVA - 1 were introduced while stirring. In all cases, a stable aqueous electrodeposition coating composition was obtained.

[0195]

Table 4

[0196] 4. Preparation of a coated substrate As test panels, various substrates were used, namely substrate S1 (degreased bare steel), S2 (steel substrate pretreated with a phosphate treatment composition (Gardobond® GB26S 6800 OC)), and S3 (zinc-plated steel substrate pretreated with a phosphate treatment composition (Gardobond® GB26S 6800 OG)). Before coating the substrates with the electrodeposition coating material, strips were cut at the edges of substrate S1 using a tin snip. Before the pretreatment of substrates S2 and S3, seven individual holes were drilled in the substrates. These holes and their edges were not sanded or polished respectively, and each was similar to the unsanded / polished edges of a real substrate.

[0197] The electrodeposition coating materials ECM-1 to ECM-8 prepared as described in item 3 were each aged at room temperature for 24 hours with stirring. Then, the electrodeposition coating materials were respectively deposited onto substrates S1 to S3 connected as the cathode within 2 to 3 minutes at a bath temperature of 32 - 33°C, rinsed with deionized water, and baked in an oven at 175°C (oven temperature) for 25 minutes (oven time). In the case of substrate S1, a deposition voltage of 140 - 160 V was used, while the electrodeposition coating materials for substrates S2 and S3 were deposited using 140 - 260 V.

[0198] 5. Results The corrosion resistance, particularly edge corrosion resistance, surface roughness, and film build-up of the cured electrodeposition coating materials prepared as described in item 4 were measured as described in items 1.7 - 1.10 above. The results are shown in Tables 5 - 7 below.

[0199] [Table 5]

[0200] [Table 6]

[0201] [Table 7]

[0202] 6. Discussion of Results The use of the aqueous dispersions (AD) of the present invention (ECM-2 and ECM-4 to ECM-8) containing a cationic resin containing various amounts of covalently bonded polyvinyl alcohol polymer groups, compared to coating materials (ECM-1 and ECM-3) not containing the dispersion (AD) of the present invention, resulted in a reduction in the surface roughness of the substrate coated with the aqueous coating material containing the aqueous dispersion, and equivalent or even improved edge corrosion protection (see Tables 5 to 7). Without wishing to be bound by this theory, it is believed that the polyvinyl alcohol polymer covalently bonded to the cationic epoxy microgel acts as a physical anchor function for the pigment-rich layer, whereby the cationic microgel is fixed to the layer, resulting in a high film thickness at the edge of the substrate. Furthermore, due to the anchor function, the cationic microgel is retained inside the formed coating layer, forming a certain stratification having a low-viscosity molten layer on the coating surface. Said stratification is necessary for good fluidity and leveling properties.

Claims

1. An aqueous dispersion (AD) containing cationic polymer particles, wherein the aqueous dispersion (AD) is a) preparing an aqueous dispersion of intermediate (I1) with a compound (C1) containing at least one free isocyanate group and at least two epoxide groups, and (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) reacting with a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, and subsequently dispersing the intermediate (I1) in water by the process of b) reacting the aqueous dispersion of the intermediate (I1) obtained in step (a) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups; c) optionally diluting the aqueous dispersion with an aqueous solution, and d) optionally at least partially removing the organic solvent present in the dispersion obtained in step (c); obtained by An aqueous dispersion in which at least one acid is present in step a) and / or step b) and / or step c).

2. The aqueous dispersion according to claim 1, wherein the compound (C1) is obtained by reacting at least one compound (C1-1) containing at least two epoxide groups, particularly at least three epoxide groups, with at least one compound (C1-2) containing at least one amine group, and further reacting the resulting product with at least one compound (C1-3) containing at least two free isocyanate groups.

3. The aqueous dispersion according to claim 1 or 2, wherein the polyvinyl alcohol polymer is a copolymer of vinyl alcohol and at least one ethylenically unsaturated monomer.

4. The aqueous dispersion according to any one of claims 1 to 3, wherein the polyvinyl alcohol polymer has a vinyl alcohol fraction of 50 to 99.9 mol%.

5. The aqueous dispersion according to any one of claims 1 to 4, wherein the polyvinyl alcohol polymer has a viscosity at 20 °C of at least 2 mPa*s as determined at a concentration of 4% by mass in water in accordance with DIN 53015:2018-07.

6. The aqueous dispersion according to any one of claims 1 to 5, wherein the polyvinyl alcohol polymer has a degree of hydrolysis of 70 to 100 mol%.

7. The aqueous dispersion according to any one of claims 1 to 6, wherein the aqueous solution (C2a-i) contains 5 to 15% by mass of a polyvinyl alcohol polymer and 85 to 95% by mass of water, in each case based on the total mass of the aqueous solution (C2a-i).

8. The aqueous dispersion according to any one of claims 1 to 7, wherein at least one compound (C3-1) containing at least one epoxide group is reacted with at least one compound (C3-2) containing at least one aromatic group and at least two hydroxyl groups in the presence of at least one solvent S2, and the resulting product is further reacted with at least one polyamine (C3-3) containing at least two blocked primary amino groups and at least one free secondary amino group to obtain the compound (C3).

9. The aqueous dispersion according to any one of claims 1 to 8, wherein the at least one acid is selected from organic acids.

10. The aqueous dispersion according to any one of claims 1 to 9, wherein the polymer particles have an average particle size (z-average) of 100 to 1,000 nm as determined in accordance with DIN EN ISO 22412:2018-09.

11. The aqueous dispersion according to any one of claims 1 to 10, wherein the aqueous dispersion (AD) contains cationic polymer particles in a total amount of 15 to 40% by mass, in each case based on the total mass of the aqueous dispersion (AD).

12. A method for preparing an aqueous dispersion (AD) containing cationic polymer particles, comprising the following steps: (1) preparing an aqueous dispersion of an intermediate (I1) from a compound (C1) containing at least one free isocyanate group and at least two epoxide groups and (i) an aqueous solution (C2a-i) of a polyvinyl alcohol polymer, or (ii) a dispersion (C2a-ii) of a polyvinyl alcohol polymer in an organic solvent S1, followed by dispersing the intermediate (I1) in water by this process, (2) reacting the aqueous dispersion of the intermediate (I1) obtained in step (1) with a compound (C3) containing at least one epoxide group and at least two blocked primary amino groups, (3) optionally diluting the aqueous dispersion with an aqueous solution, and (4) optionally removing at least part of the organic solvent present in the dispersion obtained after step (3). comprising a method in which at least one acid is present in step (1) and / or step (2) and / or step (3).

13. The following components (A) at least one aqueous dispersion (AD) according to any one of claims 1 to 11, or at least one aqueous dispersion (AD) prepared by the method according to claim 12, (B) at least one further binder B different from the cationic polymer particles contained in the aqueous dispersion (AD), (C) optionally at least one crosslinking agent (CL), (D) at least one pigment, (E) optionally at least one additive, and (F) optionally at least one catalyst An aqueous electrodeposition coating material (ECM) comprising.

14. A method for producing a substrate at least partially coated, comprising the following steps: (a) contacting the substrate at least partially with the aqueous electrodeposition coating material (ECM) according to claim 13, (b) optionally, rinsing the coating film formed in step (b) with an aqueous solution, (c) curing the coating film formed after step (a) or after any step (b), and (d) optionally, applying at least one further coating layer and curing said coating layer A method comprising.

15. A substrate at least partially coated obtained by the method according to claim 14.

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