Aqueous coating compositions containing aqueous dispersions of polyamides as thickeners - Patent Application 20070122997

Abstract

The present invention relates to an aqueous coating composition comprising at least one binder (A) comprising at least one polymer resin (A1), at least one pigment (B), and at least one thickener (C), wherein the thickener is an aqueous dispersion of a polyamide having a volume-based particle size distribution with a x10 quantile of at least 30 nm, a x50 quantile of at least 60 nm, and a x90 quantile of at most 2000 nm. The present invention also relates to a method of using the aqueous coating composition for at least partially coating an optionally coated substrate with a basecoat film, a coating method of this kind, and the substrate coated accordingly.

Description

[Technical Field]

[0001] The present invention relates to an aqueous coating composition comprising at least one binder (A) comprising at least one polymer resin (A1), at least one pigment (B), and an aqueous dispersion of at least one polyamide as a thickener. The present invention also relates to a method for using the aqueous coating composition for at least partially coating an optionally coated substrate with a base coat film, to a coating method of this kind, and to the substrates coated accordingly. [Background technology]

[0002] It is known to apply multiple coating films one on top of the other to a substrate, particularly in the field of automotive finishing, but also in other fields where coatings with good decorative effect and advantageous mechanical properties such as adhesion are required. Multi-coat paint systems are preferably applied here in the "basecoat / clearcoat" process, i.e., a pigmented basecoat material is applied first, and after a short flushing time, a clearcoat material is applied on top of it without a baking step (wet-on-wet process). The basecoat and clearcoat are then baked together. The "basecoat / clearcoat" process has become particularly important in the application of metallic effect paints for automobiles.

[0003] Economic and environmental reasons dictate the use of aqueous coating compositions when applying such multi-coat paint systems, particularly when applying the basecoat film.

[0004] The coating compositions for producing these basecoat films should be processable in the aforementioned "wet-on-wet" process. That is, after a very short pre-drying time without a baking step, it should be possible to apply a clearcoat film thereover without the occurrence of cosmetic defects such as pinholes, pits, and / or flow defects. To at least minimize such defects, the applied coating compositions typically contain, among other agents, suitable rheological aids.

[0005] Furthermore, for basecoat / clearcoat metallic effect paints, there are further requirements that must be met. The metallic effect is crucially dependent on the orientation of the metallic pigment particles within the coating film. Therefore, metallic effect basecoat materials processed by a "wet-on-wet" process must result in a coating film in which, after application, the metallic pigments are present in a preferred spatial orientation and this orientation is rapidly fixed so that it is not destroyed during further finishing operations. Suitable variables for characterizing the metallic effect are the brightness of the hue and the flop index.

[0006] EP 0 877 063 A2 discloses an aqueous coating composition containing a polyamide to ensure sufficient sedimentation stability of the pigments present in the composition. However, a disadvantage of the presence of such a polyamide as the only rheological aid in the aqueous coating composition is the occurrence of bits during processing, especially by the "wet-on-wet" process.

[0007] EP 1 153 989 A1 discloses an aqueous coating composition that contains, in addition to a polyamide such as the commercially available polyamide Disparlon® AQ-600, a metal silicate, such as the commercially available metal silicate Laponite® RD, as a further rheological aid. However, a disadvantage of the presence of such a metal silicate in an aqueous coating composition, especially in combination with the polyamide specified in EP 1 153 989 A1, is that pinholes and / or pits often occur when processing by a "wet-on-wet" process.

[0008] EP 3 183 068 B1 discloses an aqueous coating composition containing a polyamide-based thickener. The goal is to achieve excellent application properties while not adversely affecting the metallic effect of the coating composition. The thickener is prepared by mixing a polyamide with a polymeric resin, i.e., a polyurethane resin, in an organic solvent. The polyamide is added as a melt, and the resulting mixture is then mixed with water. The final step is the removal of the organic solvent. In addition to the considerable complexity of this procedure, the thickener's preparation already introduces a significant amount of specific polyurethane resin (i.e., binder resin), significantly limiting the formulation freedom of the resulting coating composition.

[0009] Furthermore, while polyamides offer certain technical advantages when used as thickeners (see above), it is generally known that they can have adverse effects, particularly on adhesive properties and appearance, and storage stability also remains an issue. Therefore, a need exists for aqueous coating compositions, particularly coating compositions such as basecoat compositions, that are suitable for processing by a "wet-on-wet" process, that do not suffer from the above-identified drawbacks. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] EP 0 877 063 A2 [Patent Document 2] EP 1 153 989 A1 [Patent Document 3] EP 3 183 068 B1 Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the object of the present invention is to provide an aqueous coating composition, more particularly an aqueous basecoat composition, that has advantages over coating compositions known from the prior art. A particular object of the present invention is to provide a coating composition that is notable for its advantageous application properties and that poses fewer environmental concerns than commonly employed compositions. Specifically, excellent rheological properties are desirable, while at the same time, adverse effects on appearance, storage stability, adhesion, and pitting should be avoided. Similarly, the composition should have a high degree of formulation flexibility, meaning that there is no significant need to include additive resin compounds, such as those required in EP 3 183 068 B1. [Means for solving the problem]

[0012] This object is achieved by the subject matter set forth in the claims and also by preferred embodiments of this subject matter set forth in the following description.

[0013] A first subject of the present invention is therefore a method for at least partially coating an optionally precoated substrate with a base coat film, at least one binder (A) comprising at least one polymer resin (A1) and optionally at least one crosslinker (A2); at least one pigment (B), and at least one thickening agent (C); an aqueous coating composition comprising: wherein the thickener (C) is an aqueous dispersion of a polyamide having a volume-based particle size distribution with a x10 quantile of at least 30 nm, a x50 quantile of at least 60 nm and a x90 quantile of at most 2000 nm.

[0014] Surprisingly, it has been found that the aqueous coating compositions of the present invention are particularly suitable for the "basecoat / clearcoat" process for applying a basecoat film to a substrate surface that has been optionally coated with a primer coat, and thus can be used as a basecoat coating composition.

[0015] It has also been surprisingly found that, in particular, the presence of the specific thickener (C) used according to the invention makes it possible to prevent the occurrence of pinholes, bits and flow defects that are often observed when typical rheological auxiliaries, such as, for example, Laponite®, are used in combination with polyamides or when polyamides are used alone as thickeners.

[0016] Furthermore, it has surprisingly been found that the presence of the particular thickener (C) used in particular according to the invention does not adversely affect appearance, color shift, storage stability and deposition properties.

[0017] Additionally, the coating compositions of the present invention are distinguished by the fact that they are water-based and therefore present fewer environmental concerns than conventional coating compositions that contain large amounts of organic solvents. DETAILED DESCRIPTION OF THE INVENTION

[0018] The terms "pops", "pinholes", "flops", "bits", "sediments" and "flow defects" are known to those skilled in the art and are defined, for example, in Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag 1998.

[0019] In connection with the coating composition of the present invention, the term "comprises" in the sense of the present invention has, for example, the meaning "consists of" in one preferred embodiment. In this preferred embodiment, as well as the components water, (A), (B) and (C), (D) and / or (E) and / or organic solvents can optionally be present in the coating composition of the present invention. All components here can in each case be present in the coating composition of the present invention in their preferred embodiments described below.

[0020] The proportions in weight percent of the components present in the coating composition of the present invention, i.e., water, (A), (B) and (C), optionally (D) and / or (E) and / or organic solvent, are based on the total weight of the coating composition and preferably total 10 weight percent.

[0021] Coating Composition The aqueous coating composition of the present invention comprises water as the liquid diluent.

[0022] The term "aqueous" in connection with the coating composition of the present invention preferably refers to a liquid coating composition that contains water as its liquid diluent, i.e., liquid solvent and / or dispersion medium, as a primary component. Thus, the aqueous coating composition of the present invention is preferably substantially free of organic solvents. However, optionally, the coating composition of the present invention may contain organic solvents in the proportions described above. Examples of such organic solvents include heterocyclic, aliphatic, or aromatic hydrocarbons, monofunctional or polyfunctional alcohols, ethers, esters, ketones, and amides, such as N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl glycol, butyl glycol, and their acetates, butyl diglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, acetone, isophorone, or mixtures thereof. The proportion of these organic solvents is preferably at most 40.0% by weight, more preferably at most 35.0% by weight, very preferably at most 30.0% by weight, and even more preferably at most 25.0% by weight, in each case based on the total proportion of liquid diluent, i.e., liquid solvent and / or dispersion medium, present in the coating composition of the present invention. In this context, the expression "substantially free of organic solvents" in relation to the coating composition of the present invention accordingly preferably means that the proportion of organic solvents therein is at most 40.0% by weight, more preferably at most 35.0% by weight, very preferably at most 30.0% by weight, and even more particularly preferably at most 25.0% by weight, in each case based on the total proportion of liquid diluents, i.e., liquid solvents and / or dispersion media, present in the coating composition of the present invention. In particular, the expression "substantially free of organic solvents" in relation to the coating composition of the present invention means that the proportion of organic solvents therein is at most 10.0% by weight to 35.0% by weight, based on the total proportion of liquid diluents, i.e., liquid solvents and / or dispersion media, present in the coating composition of the present invention. The coating composition of the present invention preferably contains at most 25% by weight, more preferably at most 20% by weight, of an organic solvent or organic solvents, based on the total weight of the coating composition.

[0023] The coating composition of the present invention is preferably a base coat composition, i.e. a coating composition suitable for producing a base coat film. The term "base coat" is known to those skilled in the art and is defined, for example, in Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag 1998.

[0024] The coating composition of the present invention preferably has a percentage solids, i.e., solid content, in the range of 10 to 50% by weight, more preferably in the range of 15 to 45% by weight, and most preferably in the range of 15 to 50% by weight, based on the total weight of the coating composition. Those skilled in the art know how to determine the percentage solids or solid content, i.e., the non-volatile fraction. The non-volatile fraction is determined according to the determination method described below.

[0025] Binder (A) The binder (A) used in the aqueous coating composition of the present invention is preferably a binder that is dispersible or soluble in water.

[0026] The term "binder" in the sense of the present invention preferably refers to the non-volatile fraction of the coating composition responsible for film formation, more particularly the polymer resin responsible for film formation, excluding the pigment (B) and fillers present therein, in accordance with DIN EN ISO 4618 (German edition, date: March 2007). The non-volatile fraction can be determined according to the method described below. The term binder (A) consequently includes not only the polymer resin (A1), but also any crosslinking agent (A2) preferably present in the respective coating composition. However, the thickener (C) is preferably not included in the term binder (A).

[0027] Suitable polymer resins (A1) are all conventional polymer resins (A1) known to those skilled in the art, such as self-crosslinking polymer resins and non-self-crosslinking polymer resins (A1). When non-self-crosslinking polymer resins (A1) are used, the binder (A) used according to the present invention may further comprise a crosslinking agent (A2). Suitable polymer resins (A1) with optionally present crosslinkers (A2) are, for example, those disclosed in EP 3 247 755 B1, EP 3 229 976 B1, WO 2014033135 A1, EP 0 228 003 A1, DE 44 38 504 A1, EP 0 593 454 B1, DE 199 48 004 A1, EP 0 787 159 B1, DE 40 09 858 A1, DE 44 37 535 A1, and WO 2005 / 021168 A1, more in particular in EP 3 247 755 B1, EP 3 229 976 B1, WO 2014033135 A1, EP 0 228 003 A1, DE 199 48 004 A1, DE 40 09 858 A1 and DE 44 37 535 A1.

[0028] The binder (A) preferably comprises at least one polymeric resin (A1) optionally having reactive functional groups that allow crosslinking reactions.

[0029] The polymer resin (A1) in the binder (A1) used according to the present invention preferably has a crosslinkable reactive functional group. Any conventional crosslinkable reactive functional group known to those skilled in the art is suitable in this context. At least one polymer resin in the binder (A) preferably has at least one functional reactive group selected from the group consisting of primary amino groups, secondary amino groups, hydroxyl groups, thiol groups, carboxyl groups, groups with at least one C=C double bond, such as vinyl groups or (meth)acrylate groups, and epoxide groups. The polymer resin (A1) in the binder (A) preferably has a functional hydroxyl group.

[0030] For the purposes of the present invention, the expressions "(meth)acrylic" or "(meth)acrylate" encompass in each case the definitions "methacrylic" and / or "acrylic" and "methacrylate" and / or "acrylate".

[0031] If the polymer resin (A1) in the binder (A) has crosslinkable functional groups such as hydroxyl groups, the proportion of crosslinkable functional groups such as hydroxyl groups is preferably in the range of 0.1% to 7.0% by weight, more preferably 0.25 to 6.5% by weight, very preferably 0.50 to 6.0% by weight, and more particularly preferably 0.75 to 5.5% by weight, in each case based on the total weight of the solids content of the polymer resin (A1) in the binder (A).

[0032] The polymer resin (A1) and the optional crosslinking agent (A2) may be exothermically or endothermically curable or crosslinkable. The polymer resin (A1) and the optional crosslinking agent (A2) may be more particularly thermally curable or crosslinkable. The polymer resin (A1) and the optional crosslinking agent (A2) are preferably curable or crosslinkable in a temperature range of from -20°C to 250°C. The polymer resin (A1) and the optional crosslinking agent (A2) are preferably crosslinkable at room temperature or at a temperature in the range of from 15°C to 80°C. Room temperature for the purposes of the present invention preferably means a temperature in the range of from 18°C ​​to 23°C. Alternatively, the polymer resin (A1) and the optional crosslinking agent (A2) may be crosslinkable only at higher temperatures, such as temperatures of ≥ 80°C, more preferably ≥ 110°C, and very preferably ≥ 140°C or ≥ 150°C. Particularly advantageously, the polymer resin (A1) and optionally the crosslinking agent (A2) present are crosslinkable at temperatures between 50 and 150°C, more preferably between 70 and 150°C, very preferably between 80 and 150°C.

[0033] The binder (A) preferably comprises at least one polymer resin (A1) selected from the group consisting of polyurethanes, polyesters, polyamides, polyureas, polystyrenes, polycarbonates, poly(meth)acrylates, vinyl ester-based resins, epoxy resins, phenyl formaldehyde resins, melamine formaldehyde resins, phenolic resins, and silicone resins, and mixtures thereof. Preferably, 70 to 100% by weight of the polymer resin is selected from at least one of the aforementioned polymers. Among the aforementioned polymers, preferably, both homopolymers and copolymers are mentioned in each case. These resins and their preparation are known to those skilled in the art. Suitable polyesters are known, for example, from DE 40 09 858 A1. Suitable polyurethanes are known, for example, from DE 199 48 004 A1 and EP 0 228 003 A1. The term "polyurethane" preferably includes, in particular, polyurethane-poly(meth)acrylates, i.e., polyurethane-modified poly(meth)acrylates. Such polyurethane poly(meth)acrylates are known to those skilled in the art, for example from DE 44 37 535 A1 and EP 3 229 976 B1.

[0034] The binder (A) preferably contains at least one polymer resin (A1) selected from the group consisting of polyurethane, polyurea, polyester, and poly(meth)acrylate, and preferably 70 to 100% by mass of the polymer resin in the binder is selected from at least one of the aforementioned polymers.

[0035] It is also possible for two or more different polymer resins (A1) to be present in the binder (A), for example two or three polymer resins (A1) which are in each case different from one another.

[0036] In a particularly preferred embodiment, the binder (A) comprises, as polymer resin (A1), at least one polyurethane (preferably 70 to 100% by weight of the polymer resin constitutes such a polyurethane), and / or, as polymer resin (A1), at least one poly(meth)acrylate (preferably 70 to 100% by weight of the polymer resin selected from such poly(meth)acrylates), and / or, as polymer resin (A1), at least one polyester (preferably 70 to 100% by weight of the polymer resin selected from such polyesters).

[0037] The binder (A) may comprise a polymeric resin (A1) cured or crosslinked with the participation of isocyanate groups and / or oligomerized or polymerized isocyanate groups, very preferably at least one corresponding polyurethane and / or polyester and / or poly(meth)acrylate.

[0038] When the binder (A) contains at least one polyurethane as the polymer resin (A1), polyurethane base resins prepared by the polyaddition reaction of hydroxyl-containing compounds, such as diol-containing polyols (e.g., hydroxyl-containing polyesters or hydroxyl-containing polyethers, and mixtures and copolymers thereof), with at least one isocyanate or polyisocyanate (including aromatic and aliphatic isocyanates, di-, tri-, and / or polyisocyanates) are particularly suitable. Typically, this requires a stoichiometric conversion of the OH groups of the polyol with the isocyanate groups of the polyisocyanate. However, the stoichiometric ratio used can be varied, since the polyisocyanate can be added to the polyol component in amounts that result in "overcrosslinking" or "undercrosslinking." In addition to the reaction of isocyanate groups with OH groups, other crosslinking reactions that can occur include, for example, dimerization and trimerization of isocyanates (to form uredione or isocyanurate). Suitable polyisocyanates and isocyanates include all polyisocyanates and isocyanates, respectively, employed and described as crosslinking agents (A2).

[0039] When the binder (A) contains at least one polyurethane as the polymer resin (A1), it is preferably prepared using a polyester polyol as the prepolymer polyol component. Suitable polyester polyols include, in particular, at least one polyol, such as at least one diol, such as ethylene glycol, propylene glycol (1,2-propanediol), trimethylene glycol (1,3-propanediol), neopentyl glycol, 1,4-butanediol, and / or 1,6-hexanediol, or at least one triol, such as a compound derived from 1,1,1-trimethylolpropane (TMP), and at least one dicarboxylic acid, such as adipic acid, terephthalic acid, isophthalic acid, orthophthalic acid, and / or dimethylolpropionic acid, and / or at least one dicarboxylic acid derivative, such as a dicarboxylic acid ester and / or a compound derived from a dicarboxylic acid anhydride, such as phthalic anhydride. Particularly preferred are polyester polyols of this type used as prepolymer polyol components, which are derived from at least one diol and / or triol selected from the group consisting of 1,6-hexanediol, neopentyl glycol, trimethylolpropane, and mixtures thereof, and at least one dicarboxylic acid (or at least one dicarboxylic acid derivative thereof) selected from the group consisting of adipic acid, terephthalic acid, isophthalic acid, orthophthalic acid, dimethylolpropionic acid, and mixtures thereof. To prepare the polyurethane resin contained in the binder (A), it is preferred to use at least one such polyester polyol together with at least one crosslinker (A2), more particularly at least one polyisocyanate such as HDI or IPDI.

[0040] To enable solutions or dispersions of this type of polyurethane and / or polyurea resin in water, it is common to incorporate ionic and / or hydrophilic segments into the polyurethane and / or polyurea chains in order to stabilize the dispersion. The soft segments used in the case of polyurethanes preferably represent 20 to 100 mol % of the total diol, preferably polyester diol, and have a number average molecular weight M of 500 to 5000 g / mol, preferably 1000 to 3000 g / mol. n The number average molecular weight may be determined by the method described below.

[0041] When the binder (A) comprises at least one poly(meth)acrylate-based polymer resin, in particular a C of acrylic acid and / or methacrylic acid 1~6 They are preferably prepared using a mixture of monomers or oligomers of esters, such as alkyl esters. Polymer synthesis is achieved by the reaction of the C—C double bonds of these monomers. Such poly(meth)acrylate-based resins can be prepared, for example, by radical polymerization initiated by the decomposition of organic peroxides.

[0042] If the binder (A) further comprises at least one crosslinking agent (A2) in addition to at least one polymer resin (A1), suitable crosslinking agents include all conventional crosslinking agents known to those skilled in the art, such as aminoplast resins, phenoplast resins, polyfunctional Mannich bases, melamine resins, benzoguanamine resins, β-hydroxyalkylamides, tris(alkoxycarbonylamino)triazines, epoxides, free and / or blocked polyisocyanates, especially blocked polyisocyanates, and also compounds having an average of at least two transesterifiable groups, such as reaction products of malonic acid diesters with polyisocyanates, or reaction products of malonic acid with monoisocyanates and polyhydric alcohol esters and partial esters. Particularly preferred crosslinking agents are blocked polyisocyanates. When blocked polyisocyanates are selected as the crosslinking agent, the aqueous coating composition of the present invention is preferably formulated as a one-component composition (1-K). When an unblocked polyisocyanate is selected as the crosslinker, the aqueous coating composition of the present invention is preferably formulated as a two-component composition (2-K).

[0043] Particularly preferred crosslinking agents (A2) are water-dispersible or water-soluble melamine resins, preferably melamine-formaldehyde condensation products, more particularly etherified melamine-formaldehyde condensation products. The water solubility or dispersibility of these products depends not only on the degree of condensation (which should be as low as possible) but also on the etherification component, with only the lowest etherification components in the alkanol or ethylene glycol monoether series producing water-soluble condensates. The most important are methanol-etherified (methylated) melamine resins. When using a solubilizing agent as an optional additional additive, it is also possible to dissolve or disperse ethanol-, propanol-, and / or butanol-etherified melamine resins, more particularly the corresponding etherified melamine-formaldehyde condensation products, in the aqueous phase.

[0044] The isocyanates used are preferably (hetero)aliphatic, (hetero)alicyclic, (hetero)aromatic, or (hetero)aliphatic-(hetero)aromatic isocyanates. Preference is given to diisocyanates containing 2 to 36, in particular 6 to 15, carbon atoms. Preferred examples include 1,2-ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4-(2,4,4)-trimethyl-1,6-hexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), 1,9-diisocyanato-5-methylnonane, 1,8-diisocyanato-2,4-dimethyloctane, 1,12-dodecane diisocyanate, ω,ω'-diisocyanatodipropyl ether, cyclobutene 1,3-diisocyanate, cyclohexane 1,3- and -1,4-diisocyanate, 3-isocyanatomethyl-3,5,5-trimethyl-cyclohexyl isocyanate (isophorone diisocyanate), anate, IPDI), 1,4-diisocyanatomethyl-2,3,5,6-tetramethylcyclohexane, decahydro-8-methyl (1,4-methanonaphthalene-2 ​​(or 3), 5-ylenediisocyanate, hexahydro-4,7-methanoindan-1 (or 2), 5 (or 6)ylenediisocyanate, hexahydro-4,7-methanoindan-1 (or 2), 5 (or 6)ylenediisocyanate, 2,4- and / or 2,6-hexahydrotoluylenediisocyanate (H6-TDI), 2,4- and / or 2,6-toluenediisocyanate (TDI), perhydro-2,4'-diphenylmethane diisocyanate, perhydro-4,4'-diphenylmethane diisocyanate (H 12MDI), 4,4'-diisocyanato-3,3',5,5'-tetramethyldicyclohexylmethane, 4,4'-diisocyanato-2,2',3,3',5,5',6,6'-octamethyldicyclohexylmethane, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,4-diisocyanatomethyl-2,3,5,6-tetramethylbenzene, 2-methyl-1,5-diisocyanatopentane (MPDI), 2 Examples of suitable polyisocyanates include 1,4-ethyl-1,4-diisocyanatobutane, 1,10-diisocyanatodecane, 1,5-diisocyanatohexane, 1,3-diisocyanatomethylcyclohexane, 1,4-diisocyanatomethylcyclohexane, tetramethylxylylene diisocyanate (TMXDI), 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane (NBDI), and mixtures of these compounds. Polyisocyanates with higher isocyanate functionality can also be used. Examples include trimerized hexamethylene diisocyanate and trimerized isophorone diisocyanate. Mixtures of polyisocyanates can also be utilized. Organic polyisocyanates suitable as crosslinker (A2) of the present invention can also be prepolymers derived from polyols, including, for example, polyether polyols or polyester polyols. The blocked polyisocyanate may be any desired isocyanate whose isocyanate groups are reacted with a compound that renders the resulting blocked polyisocyanate particularly stable to hydroxyl groups and amino groups, such as primary and / or secondary amino groups, at room temperature, i.e., at a temperature of 18 to 23° C., but reacts at elevated temperatures, for example, ≧80° C., more preferably ≧110° C., very preferably ≧130° C., particularly preferably ≧140° C., or 90° C. to 300° C., or 100 to 250° C., more preferably again 125 to 250° C., very preferably 150 to 250° C. Any desired suitable aliphatic, alicyclic, or aromatic alkyl monoalcohol can be used for blocking the isocyanate.Examples include aliphatic alcohols such as methyl, ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, 3,3,5-trimethylhexyl, decyl, and lauryl alcohol; alicyclic alcohols such as cyclopentanol and cyclohexanol; and aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol. Other suitable blocking agents include hydroxylamines such as ethanolamine, oximes such as methyl ethyl ketone oxime, acetone oxime, and cyclohexanone oxime, and amines such as dibutylamine and diisopropylamine.

[0045] The aqueous coating composition of the present invention preferably comprises as crosslinker (A2) at least one optionally alkylated melamine-formaldehyde condensation product.

[0046] The crosslinking agent (A2) is preferably a crosslinking agent in dispersion or solution in water. To promote crosslinking, a suitable catalyst can be added to the aqueous coating composition. Those skilled in the art are also aware of such catalysts.

[0047] The aqueous coating composition of the present invention preferably has a solids content for the at least one binder (A) in the range of 10 to 60% by weight, more preferably 15 to 40% by weight, very preferably 20 to 35% by weight, in each case based on the total weight of the aqueous coating composition.

[0048] The aqueous coating composition of the present invention preferably comprises the crosslinker (A2) in an amount of 5 to 40% by weight, preferably 10 to 35% by weight, more preferably 15 to 30% by weight, based on the total weight of the polymer resin (A1) in the coating composition, these amounts being in each case based on the respective solids content.

[0049] Pigment (B) The coating composition of the present invention comprises at least one pigment (B).

[0050] The pigment (B) is preferably in the form of a dispersion or solution in water.

[0051] Particularly suitable as pigments (B) are organic and / or inorganic, colouring and / or extending pigments, more particularly pigments which preferably have at least two of these properties.

[0052] In one embodiment, the at least one pigment (B) is an effect pigment or a mixture of at least one effect pigment with at least one pigment that is not itself an effect pigment but is preferably selected from the group consisting of organic and inorganic, color and extender pigments, and pigments that preferably have at least two of these properties.

[0053] Those skilled in the art are familiar with the concept of effect pigments. Corresponding definitions can be found, for example, in Roempp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag 1998. Effect pigments are preferably pigments that impart optical effects or color and optical effects, more particularly optical effects. Corresponding classification of pigments is carried out in accordance with DIN 55945 (date: December 2011). The pigment (B) is selected from the group consisting of optionally coated organic or inorganic effect pigments, for example optionally coated metallic effect pigments, optionally coated metal oxide effect pigments, optionally coated effect pigments composed of metals and non-metals, and optionally coated non-metallic effect pigments.

[0054] Explicit examples include silicate-coated metallic effect pigments and optionally coated non-metallic effect pigments, such as pearlescent pigments, more particularly mica pigments. More preferably, pigment (B) is selected from the group consisting of metallic effect pigments and silicate-coated metallic effect pigments.

[0055] Examples of metal effect pigments are aluminum effect pigments, iron effect pigments, or copper effect pigments. Preferred are optionally coated, for example silanized and / or chromated, aluminum effect pigments, more particularly the products available from Eckart, such as Stapa® Hydrolac, Stapa® Hydroxal, Stapa® Hydrolux and Stapa® Hydrolan, most preferably Stapa® Hydrolux and Stapa® Hydrolan. The effect pigments (B) used according to the present invention may be in any conventional form known to those skilled in the art, for example in leaflet and / or platelet form, more particularly in (corn) flake or silver dollar form.

[0056] Examples of effect pigments composed of metals and non-metals include iron oxide coated aluminum pigments, glass leaflets coated with metal, more particularly aluminum, or interference pigments comprising a reflective layer made of metal, more particularly aluminum, as described, for example, in European Patent Application EP 0 562 329 A2.

[0057] Examples of non-metallic effect pigments include pearlescent pigments, more particularly mica pigments, graphite pigments coated with metal oxides and having platelet morphology, interference pigments that do not contain a metallic reflective layer and show strong color flop, effect pigments based on iron oxides, or organic liquid crystal effect pigments.

[0058] For further details regarding the effect pigments which are preferably employed according to the invention as pigment (B), see Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag, 1998, p. 176 "Effect pigments" and p. 380 and 381 "Metal oxide-mica pigments" to "Metallic pigments".

[0059] Suitable pigments as non-effect pigments (B) may be selected from the group consisting of organic and inorganic, color and extender pigments, preferably pigments having at least two of these properties, and nanoparticles. Examples of suitable inorganic color pigments include white pigments such as titanium dioxide, white zinc, zinc sulfide, or lithopone; black pigments such as carbon black, iron manganese black, or spinel black; chromatic pigments such as chromium oxide, chromium oxide hydrate green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, ultramarine violet or cobalt violet and manganese violet, red iron oxide, cadmium sulfoselenide, molybdate red, or ultramarine red; brown iron oxide, mixed brown, spinel phase and corundum phase, or chrome orange; or yellow iron oxide, nickel titanium yellow, chrome titanium yellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow, or bismuth vanadate. Examples of suitable organic color pigments include monoazo pigments, disazo pigments, anthraquinone pigments, benzimidazole pigments, quinoacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindolinone pigments, azomethine pigments, thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments, or aniline black. Examples of suitable extender pigments or fillers include chalk, calcium sulfate, barium sulfate, silicates such as talc or kaolin, oxides such as silica, aluminum hydroxide or magnesium hydroxide, or organic fillers such as textile fibers, cellulose fibers, polyethylene fibers, or polymer powders; for further details, see "Fillers" on page 250 of Römpp Lexikon, Lacke und Druckfarben, Georg Thieme Verlag, 1998. The nanoparticles are preferably selected from the group consisting of main group metals and transition group metals and their compounds. The main group metals and transition group metals are preferably selected from the metals of main groups 3 to 5, transition groups 3 to 6, and groups 1 and 2 of the periodic table of the elements, and also from the lanthanides.Particularly preferred for use are boron, aluminum, gallium, silicon, germanium, tin, arsenic, antimony, silver, zinc, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and cerium, more particularly aluminum, silicon, silver, cerium, titanium, and zirconium. The metal compounds are preferably oxides, oxide hydrates, sulfates, or phosphates. Silver, silicon dioxide, aluminum oxide, aluminum oxide hydrate, titanium dioxide, zirconium oxide, cerium oxide, and mixtures thereof are preferred, more preferably silver, cerium oxide, silicon dioxide, aluminum oxide hydrate, and mixtures thereof, most preferably aluminum oxide hydrate, and most particularly boehmite. These nanoparticles preferably have an average primary particle size of less than 50 nm, more preferably 5 to 50 nm, and particularly preferably 10 to 30 nm. The primary particle size here is preferably determined by a laser diffraction method, more preferably by a laser granulometry method according to ISO 13320-1 (date: September 2009).

[0060] The amount of pigment (B) employed in the coating composition of the present invention can vary widely depending on the inventive use of the pigment coating composition. The amount of pigment (B) based on the coating composition of the present invention is preferably 0.1 to 80% by weight, more preferably 0.5 to 70% by weight, very preferably 1.0 to 60% by weight, particularly preferably 1.5 to 50% by weight, and most particularly preferably 2.0 to 40% by weight.

[0061] Thickener (C) The coating composition of the present invention comprises at least one thickener (C) which is an aqueous dispersion of a polyamide having a volume-based particle size distribution with a x10 quantile of at least 30 nm, a x50 quantile of at least 60 nm, and a x90 quantile of at most 2000 nm.Thus, the thickener (C) is an aqueous dispersion of a specific polyamide, more particularly a polyamide having a specific particle size distribution within the aqueous dispersion.

[0062] It has surprisingly been found that these particular polyamide dispersions comprising particles of a particular particle size distribution provide the technical effects and solve the problems described in the background section. Specifically, the application of the above dispersions in aqueous coating compositions provides technical advantages over aqueous coating compositions comprising standard polyamide dispersions (or other polyamide thickeners not having the particular particle size distribution as defined above) as thickeners.

[0063] Preferably, the aqueous polyamide dispersion (C) has a volume-based particle size distribution with a x10 quantile of 30 to 120 nm, a x50 quantile of 60 to 300 nm, and a x90 quantile of 200 to 2000 nm, more preferably in the following ranges: a x10 quantile of 50 to 90 nm, a x50 quantile of 100 to 250 nm, and a x90 quantile of up to 1000 nm, or a x10 quantile of 60 to 80 nm, a x50 quantile of 100 to 200 nm, and a x90 quantile of 300 to 550 nm.

[0064] Polyamides and their preparation are generally known to those skilled in the art. For example, their preparation involves the addition of at least one polycarboxylic acid, preferably an aliphatic C3-C 22 Dicarboxylic acids, aliphatic C 14 ~C 22 At least one polycarboxylic acid selected from the group consisting of polymers such as dimers and trimers of monocarboxylic acids, e.g., dimeric fatty acids, and mixtures thereof, is mixed with at least one polyamine, preferably at least one aliphatic C2-C 12 and a diamine, wherein the reaction product obtained by the process is optionally subsequently contacted with at least one preferably basic neutralizing agent. For details of the polyamide and the individual processes for its production, see below.

[0065] The preparation of aqueous dispersions of polyamides is also generally known, for example by a batch procedure, i.e., by feeding a melt of the polyamide and adding water continuously (e.g., dropwise) or by continuously adding the polyamide to the respective aqueous phase, for example, after raising its temperature to, for example, 80 to 140°C, to thereby incorporate the polyamide in the form of a melt into the aqueous dispersion. Of course, such preparations may also involve the application of known additives, such as emulsifiers or dispersants, to promote the formation of such dispersions.

[0066] The production of the particular aqueous dispersions of polyamides as applied in accordance with the present application is a continuous production, more particularly a continuous jet production, i.e. (i) continuously introducing a jet stream of water and fluid (liquefied, e.g., molten) polyamide into a reactor via an inlet therein; (ii) continuously dispersing the jet stream, and thus the water and polyamide, in the reactor; and (iii) continuously discharging the aqueous dispersion thus produced from the reactor through an outlet of the reactor; to obtain aqueous polyamide dispersions.

[0067] The jet flow can be manipulated and adjusted to individual needs using conventional pumps, such as gear or piston pumps.

[0068] Preferably, the water and polyamide are heated to a temperature above 100° C., ie the formation of the dispersion in the jet reactor also takes place at such a high temperature.

[0069] In the context of the present invention, it is important that the polyamide is included in the coating composition of the present invention in the form of a specific aqueous dispersion as outlined above. This allows the aqueous dispersion to be applied directly to the composition. Alternatively, the aqueous dispersion can be applied via an intermediate (i.e., the aqueous dispersion of the polyamide is included in an intermediate, such as a specific premix or slurry, which is then applied during the preparation of the coating composition).

[0070] The coating composition of the present invention comprises at least one aqueous dispersion of at least one thickener (C), which is an aqueous polyamide dispersion having a volume-based particle size distribution with a x10 quantile of at least 30 nm, a x50 quantile of at least 60 nm, and a x90 quantile of at most 2000 nm. Thus, thickener (C) is an aqueous dispersion of a particular polyamide, more particularly a polyamide having a particular particle size distribution within the aqueous dispersion.

[0071] The coating composition of the invention preferably has a solids content, with respect to the at least one polyamide of the dispersion, in the range of 0.1 to 10% by weight, more preferably 0.2 to 7.5% by weight, very preferably 0.3 to 5% by weight and more particularly preferably 1.0 to 9.0% by weight, in each case based on the total weight of the coating composition.

[0072] polyamide The polyamide used is preferably obtained by reaction of at least one polycarboxylic acid (C1a) with at least one polyamine (C1b).

[0073] The term "polycarboxylic acid" in the sense of the present invention preferably also refers to the corresponding polycarboxylic acid derivatives, such as the corresponding polycarboxylic acid esters and / or polycarboxylic acid anhydrides, which can be used to prepare polyamides.

[0074] For the purposes of the present invention, the term "polycarboxylic acid" (C1a) preferably includes carboxylic acids having two or more carboxyl groups, for example, 2, 3, 4, 5, or 6 carboxyl groups. Polycarboxylic acids more preferably have two or three carboxyl groups. Polycarboxylic acids having two carboxyl groups are dicarboxylic acids, and polycarboxylic acids having three carboxyl groups are tricarboxylic acids. The polycarboxylic acids (C1a) used in the present invention may be aromatic, semi-aromatic, alicyclic, semi-alicyclic, or aliphatic, and are preferably aliphatic. The polycarboxylic acids (C1a) used in the present invention preferably have 4 to 66 carbon atoms per molecule.

[0075] Particularly preferably, the polycarboxylic acid (C1a) used in preparing the polyamide (C1) employed in the present invention is an aliphatic C3-C 22 Dicarboxylic acids, aliphatic C 14 ~C 22 The polycarboxylic acids (C1a) used in preparing the polyamides (C1) employed in the present invention are selected from the group consisting of polymers of monocarboxylic acids, more particularly dimers and trimers, and mixtures thereof. Highly preferably, the polycarboxylic acids (C1a) used in preparing the polyamides (C1) employed in the present invention are aliphatic C3-C 22 Dicarboxylic acids, aliphatic C3-C 22 dimers of monocarboxylic acids, and mixtures thereof.

[0076] The term “aliphatic C3~C 22 The term "dicarboxylic acid" in the sense of the present invention refers to aliphatic C3-C6 dicarboxylic acids, preferably saturated or unsaturated, preferably saturated, having a total of 3 to 22 carbon atoms, i.e. 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 or 22 carbon atoms. 22 Dicarboxylic acids, preferably aliphatic C3-C having a total of 3 to 20 carbon atoms, i.e., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms 20Dicarboxylic acids, in each case having exactly two -C(=O)-OH groups, i.e., for example, C1-C2, which have a total of 1 to 20 carbon atoms as well as these two -C(=O)-OH groups. 20 Aliphatic C3-C with aliphatic radicals 22 The term "aliphatic" here preferably encompasses acyclic saturated or unsaturated, preferably unsaturated, branched or unbranched aliphatic radicals. Those skilled in the art will recognize that C3-C 22 The unsaturated bond in dicarboxylic acid is C4-C 22 It is clear that this is only possible for dicarboxylic acids. An unsaturated aliphatic radical in this context has at least one, preferably one, two, three, four, or five, more preferably one, two, three, or four, and very preferably one, two, or three carbon-carbon double bonds. Aliphatic C3-C 22 The dicarboxylic acid may be a natural or synthetic dicarboxylic acid. 22 Dicarboxylic acids are OH, OC 1~4 Aliphatic radicals, =O, NH2, NH(C 1~4 Aliphatic radical), N(C 1~4 The substituents may be on the same or different carbon atoms, and may be optionally substituted one or more times, for example, two, three, four, or five times, with at least one substituent selected from the group consisting of aliphatic radicals, such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, and hexadecanedicarboxylic acid. 22 Dicarboxylic acids are preferred.

[0077] “Aliphatic C 14 ~C 22 The term "monocarboxylic acid" in the sense of the present invention refers to aliphatic C carboxylic acids, preferably saturated or unsaturated, preferably unsaturated, having a total of 14 to 22 carbon atoms, i.e. 14, 15, 16, 17, 18, 19, 20, 21 or 22 carbon atoms. 14 ~C 22Monocarboxylic acids, preferably aliphatic C having a total of 16 to 20 carbon atoms, i.e., 16, 17, 18, 19, or 20 carbon atoms 16 ~C 22 Monocarboxylic acids, aliphatic C12 carboxylic acids, which in each case have exactly one -C(=O)-OH group, i.e., as well as this one -C(=O)-OH group, have an aliphatic radical having a total of 13 to 21 carbon atoms, i.e., 13, 14, 15, 16, 17, 18, 19, 20 or 21 carbon atoms, preferably 15 to 19 carbon atoms, i.e., 15, 16, 17, 18 or 19 carbon atoms. 14 ~C 22 It refers to a monocarboxylic acid. Here, the term "aliphatic" preferably includes acyclic saturated or unsaturated, preferably unsaturated, branched or unbranched aliphatic radicals. Here, the unsaturated aliphatic radical has at least one, preferably 1, 2, 3, 4, or 5, more preferably 1, 2, 3, or 4, and very preferably 1, 2, or 3 carbon double bonds. Aliphatic C 14 ~C 22 The monocarboxylic acid may be a natural or synthetic fatty acid. 14 ~C 22 Monocarboxylic acids are OH, OC 1~4 Aliphatic radicals, =O, NH2, NH(C 1~4 Aliphatic radical), N(C 1~4 and optionally substituted one or more times, for example, two, three, four, or five times, with at least one substituent selected from the group consisting of myristic, pentadecanoic, palmitic, margaric, stearic, nonadecanoic, arachidic, henicosanoic, docosanoic, myristoleic, palmitoleic, petroselinic, oleic, elaidic, wasenic, gadoleic, icosenoic, cetoleic, erucic, linoleic, linolenic, calendulic, punicic, elaiostearic, arachidonic, timnodonic, clupanodonic, and cervonic acids. 14 ~C 22Monocarboxylic acids are preferred. Aliphatic C carboxylic acids selected from the group consisting of palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, wasenic acid, gadoleic acid, icosenoic acid, linoleic acid, linolenic acid, calendulic acid, punicic acid, elaiostearic acid, arachidonic acid, and thymnodonic acid. 16 ~C 20 Monocarboxylic acids are preferred. Aliphatic C carboxylic acids are selected from the group consisting of stearic acid, petroselinic acid, oleic acid, elaidic acid, vasenic acid, linoleic acid, linolenic acid, calendulic acid, punicic acid, and elaostearic acid, more particularly selected from the group consisting of stearic acid, oleic acid, linoleic acid, and linolenic acid, and most preferably selected from the group consisting of oleic acid, linoleic acid, and linolenic acid. 18 Monocarboxylic acids are preferred.

[0078] Those skilled in the art will recognize aliphatic C 14 ~C 22 To provide polymers of monocarboxylic acids, more particularly dimers and trimers, i.e., polymerized, e.g., dimerized, trimerized aliphatic C 14 ~C 22 Monocarboxylic acids and more highly polymerized aliphatic C 14 ~C 22 Processes for the preparation of monocarboxylic acids are known, for example, from DE 25 06 211 A1, US 2,793,219A, and US 2,955,121A. Polymerized aliphatic C 14 ~C 22 The monocarboxylic acid is preferably OH, OC 1~4 Aliphatic radicals, =O, NH2, NH(C 1~4 Aliphatic radical), N(C 1~4 The polymerized aliphatic C groups may be optionally substituted one or more times, for example, two, three, four, or five times, with at least one substituent selected from the group consisting of aliphatic radicals, and the substitutions may be on the same or different carbon atoms. 14 ~C 22 The starting material used to prepare the monocarboxylic acid is at least a monounsaturated aliphatic C14 ~C 22 The resulting polymerized, e.g., dimerized and trimerized, aliphatic C 14 ~C 22 The monocarboxylic acids are in each case separated from one another and from the higher polyvalent polymerization products by distillation and can optionally be subjected to further conversion reactions, such as, for example, hydrogenation.

[0079] The term "polyamine" (C1b) in the sense of the present invention preferably refers to a compound having at least two, preferably terminal, primary amino groups. However, in total, the polyamine may have up to 10 amino groups, i.e., in addition to at least two primary amino groups, up to 8 further amino groups, preferably primary or secondary amino groups. A "polyamine" in the sense of the present invention may be a (hetero)aliphatic, (hetero)alicyclic, or (hetero)aromatic polyamine. The polyamine is preferably a diamine or triamine, more preferably a diamine. The polyamine (C1b) used in the present invention preferably has 2 to 20, more preferably 2 to 12 carbon atoms per molecule. The polyamine preferably has OH, OC, or OH groups. 1~4 Aliphatic radicals, =O, NH2, NH(C 1~4 Aliphatic radical), N(C 1~4 aliphatic radicals), the substitutions can be on the same or different carbon atoms.

[0080] Highly preferably, the polyamines (C1b) used to prepare the polyamides (C1) used in the present invention are aliphatic C2-C 20 Highly preferably, the polyamine (C1b) used to prepare the polyamide (C1) used in the present invention is selected from the group consisting of aliphatic C2-C 12 The diamine is selected from the group consisting of diamines.

[0081] “Aliphatic C2~C20 The term "diamine" in the sense of the present invention refers to an aliphatic C2-C3 diamine, preferably saturated or unsaturated, preferably saturated, having a total of 2 to 20 carbon atoms, i.e. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. 20 Diamines, preferably aliphatic C2-C having 2 to 12 carbon atoms, i.e., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms 12 The term "aliphatic" refers to a diamine, which in each case has exactly two, preferably terminal, -NH2 groups. The term "aliphatic" here preferably encompasses acyclic saturated or unsaturated, preferably saturated, branched or unbranched aliphatic radicals. An unsaturated aliphatic radical in this context has at least one, preferably 1, 2, 3, 4, or 5, more preferably 1, 2, 3, or 4, and very preferably 1, 2, or 3 carbon double bonds. Aliphatic C2-C 20 Diamines are OH, OC 1~4 Aliphatic radicals, =O, NH2, NH(C 1~4 Aliphatic radical), N(C 1~4 aliphatic radicals), and the substitutions can be on the same or different carbon atoms. 20 The diamine is preferably selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane (hexamethylenediamine), 1,7-diaminoheptane, 1,8-diaminooctane (octamethylenediamine), 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, and 1,12-diaminododecane.

[0082] The polyamide is preferably an aliphatic C3-C 22 Dicarboxylic acids, aliphatic C 14 ~C 22at least one polycarboxylic acid (C1a) selected from the group consisting of polymers such as dimers and trimers of monocarboxylic acids, and mixtures thereof, and at least one aliphatic C2-C 12 It can be obtained by reaction with diamine (C1b).

[0083] The reaction of at least one polycarboxylic acid (C1a) with at least one polyamine (C1b) is carried out in a solvent, preferably an organic solvent. The polyamide is preferably a polyamine used as component (C1b), more particularly an aliphatic C2-C 12 per amino group of the diamine, at least 1.0 mol, more preferably at least 1.1 mol, very preferably at least 1.2 mol or at least 1.4 mol of polycarboxylic acid (C1a), more particularly aliphatic C3-C 22 Dicarboxylic acids and aliphatic C 14 ~C 22 It is prepared using a polycarboxylic acid (C1a) selected from the group consisting of dimers of monocarboxylic acids.

[0084] For example, 1 mole of aliphatic C2-C 12 If a diamine is used as component (C1b), then in this case at least 1.0 mol, more preferably at least 1.1 mol, very preferably at least 1.2 mol or at least 1.4 mol of an aliphatic C3-C 22 Dicarboxylic acids and aliphatic C 14 ~C 22 Polycarboxylic acids (C1a) selected from the group consisting of dimers of monocarboxylic acids are used to prepare the polyamides.

[0085] The polyamide preferably has an acid number in the range of 1 to 200 mg, more preferably 20 to 120 mg, and very preferably 30 to 100 mg KOH per g of polyamide. Those skilled in the art know how to measure the acid number. The acid number is preferably determined according to DIN EN ISO 2114 (dated June 2002).

[0086] The acid value of the polyamide used in the present invention can be controlled and adjusted by contacting and reacting the polyamide obtained after the reaction with at least one neutralizing agent, preferably through the amount of neutralizing agent used. Corresponding suitable, preferably basic, neutralizing agents are known to those skilled in the art. One preferred neutralizing agent is an amino alcohol, and dimethylethanolamine (DMEA) is particularly suitable.

[0087] The polyamide is preferably produced by a process comprising at least the following steps: at least one polycarboxylic acid (C1a), preferably aliphatic C3-C 22 Dicarboxylic acids, aliphatic C 14 ~C 22 At least one polycarboxylic acid selected from the group consisting of polymers such as dimers and trimers of monocarboxylic acids, and mixtures thereof, is mixed with at least one polyamine (C1b), preferably at least one aliphatic C2-C 12 By reacting with diamine (C1b), You can get The reaction product obtained by this step is then optionally contacted with at least one neutralizing agent, preferably a basic one. The acid value of the reaction product obtained by this step can be adjusted or reduced by reacting the free carboxyl groups with the neutralizing agent. The at least one neutralizing agent is preferably used in an amount such that 60 to 90 mol %, more preferably 70 to 90 mol % or 75 to 85 mol % of the free carboxyl groups are neutralized.

[0088] The polyamide used in the present invention preferably has a melting point in the range of 50°C to 120°C, more preferably in the range of 55°C to 100°C.

[0089] Further thickeners (D) The coating composition of the present invention may optionally comprise at least one additional thickener (D) different from component (C), such as at least one thickener (D) selected from the group consisting of metal silicates, poly(meth)acrylic acid-based thickeners, polyurethane-based thickeners, polymer waxes, and mixtures thereof.

[0090] The metal silicates are preferably selected from the group of smectites. Particularly preferably, the smectites are selected from the group of montmorillonite and hectorite. Montmorillonite and hectorite are in particular selected from the group consisting of aluminum magnesium silicate, and also sodium magnesium and sodium magnesium fluorolithium phyllosilicates. These inorganic phyllosilicates are sold under the trade name Laponite®.

[0091] The poly(meth)acrylic acid-based thickeners are optionally crosslinked and / or neutralized with a suitable base. Examples of such poly(meth)acrylic acid-based thickeners include "alkali swellable emulsions" (ASEs) and their hydrophobically modified variants, "hydrophilically modified alkali swellable emulsions" (HASEs). The poly(meth)acrylic acid-based thickeners are preferably anionic. Corresponding products such as Rheovis® AS 1130 are commercially available.

[0092] The polyurethane-based thickener is optionally crosslinked and / or neutralized with a suitable base. Corresponding products such as Rheovis® PU 1250 are commercially available. When at least one polyurethane is used as polymer (C2), the polyurethane-based thickener is preferably different from this polymer (C2). When at least one polyurethane is used as polymer resin (A1), the polyurethane-based thickener is preferably different from this polymer resin (A1).

[0093] Examples of suitable polymer waxes include optionally modified polymer waxes based on ethylene-vinyl acetate copolymers, corresponding products being commercially available, for example, under the trade name Aquatix®.

[0094] When the coating composition of the present invention comprises at least one further thickener (D), the relative weight ratio of thickener (C) to further thickener (D) in the coating composition of the present invention is preferably in the range of 100:1 to 1:1, more preferably in the range of 80:1 to 1:1, all figures being based on the solids content of the components.

[0095] Additive (E) The coating composition of the present invention may contain one or more commonly employed additives as component (E), depending on its desired application. These additives (E) are preferably selected from the group consisting of antioxidants, preservatives, wetting agents, dispersants, emulsifiers, flow control aids, solubilizers, defoamers, wetting agents, stabilizers, preferably heat stabilizers and / or in-process stabilizers, and UV and / or light stabilizers, light protectants, defoamers, inhibitors, catalysts, waxes, wetting agents, dispersants, softeners, flame retardants, reactive diluents, carrier media, resins, waxes, hydrophobizing agents, hydrophilizing agents, impact modifiers, swelling agents, processing aids, plasticizers, and mixtures of the aforementioned additional additives. The amount of additive (E) in the coating composition of the present invention may vary. The amount is preferably 0.01 to 20.0% by mass, more preferably 0.05 to 18.0% by mass, very preferably 0.1 to 16.0% by mass, particularly preferably 0.1 to 14.0% by mass, more particularly preferably 0.1 to 12.0% by mass, and most preferably 0.1 to 10.0% by mass, based on the total mass of the coating composition of the present invention.

[0096] Method for producing aqueous coating composition The present invention further provides a method for making the coating composition of the present invention.

[0097] The coating composition of the present invention can be prepared by first preparing an aqueous dispersion of at least one thickener (C), i.e. at least one polyamide, obtainable as outlined herein.

[0098] Subsequently, the resulting aqueous dispersion of at least one polyamide as thickener (C) is mixed with the further components used according to the invention to prepare the coating composition of the invention, namely components (A) and (B), and optionally (D), (E), an organic solvent, and optionally further water, for example by means of a high-speed stirrer, a stirred tank, a stirred mill, a dissolver, a kneading apparatus, or an in-line dissolver.

[0099] How to use A further subject of the present invention is the use of the coating composition of the present invention for at least partially coating an optionally coated substrate with a basecoat film.

[0100] Examples of suitable substrates include coated metal or plastic articles, such as automobile bodies and parts, including automobiles, trucks, motorcycles, buses, and the like, metal or plastic appliance parts, and the like.

[0101] Method, basecoat film, and substrate A further subject of the present invention is a method for producing a pharmaceutical composition comprising at least one step (a): (a) at least partially coating a substrate, optionally coated with at least one basecoat film, with the aqueous coating composition of the present invention. a method for at least partially coating a substrate that is optionally coated with a basecoat film, comprising:

[0102] Step (a) is carried out by at least partial contact of the substrate with the coating composition of the present invention.

[0103] Step (a) may optionally be followed by a further step (b), which is the application of a further coating film, preferably a clear coat film, to the base coat film applied by step (a). In that case, the method of the present invention is a method for producing a multi-layer coating system.

[0104] A further subject of the present invention is a base coat film obtainable by at least partially coating at least one optionally coated substrate with the aqueous coating composition of the present invention or obtainable by the method of the present invention.

[0105] A further subject of the present invention is a substrate at least partially coated with the aqueous coating composition of the present invention or with the basecoat film of the present invention.

[0106] The coating compositions of the present invention can be applied to the article to be coated directly or after a prior, at least partial application of a primer coating composition, such as a cationically electrodepositable coating composition (cathodic electrocoat material), and, if necessary, after at least partial application of a further coating composition to the cathodic electrocoat. This is preferably followed by drying of these coating films. The coating compositions of the present invention are preferably applied as a paint system to automobile bodies and their components. The metal article to be coated is preferably pre-treated chemically with a phosphate and a chromate, preferably a metal phosphate, more particularly a phosphate such as zinc phosphate. Furthermore, known conventional materials can be employed as undercoating and intermediate coating compositions.

[0107] The coating composition of the present invention can be coated onto these target substrates (including those optionally at least partially coated with an undercoating composition and optionally at least partially coated with an intermediate coating composition by a suitable method) by electrostatic coating, air spray coating, or airless spray coating. The resulting coating film thickness, as a cured coating film, is preferably in the range of 5 to 35 μm, more particularly 10 to 25 μm. The coating film can be dried, for example, by heating at 50 to 100°C (oven temperature) for 2 to 40 minutes, preferably 5 to 20 minutes.

[0108] A clear coating composition can be coated onto the coating film of the coating composition of the present invention, either after curing or without curing, i.e., on the coated surface, by a "2-cure 1-bake" process or a "2-cure 2-bake" process.

[0109] Furthermore, the coating compositions of the present invention are also suitable for use in double coating (wet-on-wet coating) applications where, after a short pre-drying period, a clear coat material is applied and baked together with the first coated film (3C1B).

[0110] To apply this type of clear coat, the clear coating composition of the present invention is first applied to the target substrate by the method described above. The solids content of the coating composition is preferably controlled to 30 to 80% by mass, and the resulting coating film is then cured by heating, or the clear coating composition can be applied to the coated surface of the substrate by electrostatic coating, air spray coating, or airless spray coating, either in an uncured state or after the coating film has been cured. The film thickness of the clear coating composition is preferably generally in the range of 5 to 100 μm, more particularly 20 to 80 μm, based on the cured coating film. The entire coating film can be cured by heating at 100 to 180°C for 10 to 40 minutes.

[0111] Measurement method 1. Determination of Acid Value The acid number is determined using "Method A" in accordance with DIN EN ISO 2114 (date: June 2002). The acid number corresponds to the mass (mg) of potassium hydroxide required to neutralize 1 g of sample under the conditions specified in DIN EN ISO 2114. The stated acid number corresponds to the total acid number stated in the DIN standard.

[0112] 2. Determination of Nonvolatile Fraction The non-volatile content (also called solids content) is determined according to DIN EN ISO 3251 (date: June 2008). This is done by weighing 1 g of sample into a pre-dried aluminum dish, drying it in a drying oven at 130 °C for 60 minutes, then cooling it in a desiccator and weighing it again. The residue relative to the total amount of sample used corresponds to the non-volatile fraction.

[0113] 3. Determining the Film Thickness The thickness of the coating film (layer) is determined according to procedure 12A of DIN EN ISO 2808 (date: May 2007) using a MiniTest® 3100-4100 measuring device (ElektroPhysik).

[0114] 4. Evaluation of homogeneity or occurrence of pits after incorporation of polyamide dispersion into test coating The mixture of the test coating with the polyamide dispersion according to the invention (or the comparative composition) is visually evaluated for the homogeneity of the resulting mixture or for the occurrence of spots (bits), using the following criteria:

[0115] Homogeneity: After 10 minutes of stirring, it is evaluated to what extent a homogeneous mixture is formed, i.e. whether the test coating and the polyamide dispersion can be mixed on a macroscopic scale into a single-phase mixture, or whether two or more phases form during metering or within a few minutes after stirring due to segregation.

[0116] It is assessed qualitatively on a scale of 1 to 5 (1 = very easy to incorporate or very homogeneous / 5 = very difficult to incorporate or very heterogeneous).

[0117] To verify the blending or homogeneity, a commercially available 1 L tin can (diameter: approx. 110 mm / height: approx. 140 mm) is filled two-thirds with the corresponding test coating. After the addition of the respective polyamide dispersion, the mixture is stirred for 10 minutes using a conventional laboratory mixer (e.g., Vollrath, model EWTHV 0.5) with a Lenart disc (diameter: 65 mm). The simplified Reynolds number Re' for the stirring process is up to 1000. R Care must be taken to achieve essentially laminar mixing but not turbulent dispersion.

[0118] Simplified Reynolds number Re' for stirring processes R is known in the art and is defined as follows:

number

[0119] The density of a typical waterborne base coat was determined according to DIN 53217-2:1991-03: 1135 kg m -3 The determined value of is assumed for all water-borne base coats according to the invention and not according to the invention in a simplified manner. For the dynamic viscosity which is actually shear-dependent, a value of 0.1 Pa·s is assumed for all samples (see, for example, www.chemie.de / lexikon / Viskosit%C3%A4t.html of 2018.08.29), and therefore the simplified Reynolds number Re' for the stirring process. R becomes the following term:

[0120]

number

[0121] Bits: After incorporating each polyamide dispersion, the corresponding test varnish was applied to a 9 x 15 cm glass panel with a 150 μm box doctor blade. After leaving the film wet for 60 minutes at room temperature (23 °C), the film was visually evaluated for the presence or absence of mottle by holding it up to a light source to avoid mistaking air pockets for mottle. The evaluation was graded from 1 to 5 (1 = no mottle, 5 = very mottle).

[0122] 5. Determining Stability After Oven Storage / Agitation Test To determine the storage stability of coating compositions according to the invention (or comparative coating compositions), they were either stored for a certain period of time at 40°C or subjected to a stirring test (700 g of material placed in a 1 L tin can with an internally painted lid and stirred for 21 days in a mixing rack at a stirring rate of 20 min-1) according to one of the methods of DIN 53019-1 (dated September 2008) and calibrated under temperature-controlled conditions (23.0°C ± 0.2°C) according to DIN 53019-2 (dated February 2001). The corresponding samples were first sheared for 5 minutes at a shear rate of 1000 s-1 (loading phase) and then for 8 minutes at a shear rate of 1 s-1 (relief phase). The average viscosity level during the loading phase (high shear viscosity) and the level after the 8-minute relief phase (low shear viscosity) are determined from the measurement data, and the values ​​before and after loading are compared by calculating the respective percentage changes.

[0123] 6. Evaluation of runner appearance (limit of sagging) To determine the runner tendency of a coating composition according to the invention (or a comparative coating composition), a multilayer coating is produced in accordance with DIN EN ISO 28199-1 (date: January 2010) and DIN EN ISO 28199-3 (date: January 2010) according to the following general rules: A perforated steel sheet measuring 57 cm x 20 cm and coated with standard EDCoat (CathoGuard® 800 from BASF Coatings GmbH) (according to DIN EN ISO 28199-1, point 8.1, version A) is prepared as per DIN EN ISO 28199-1, point 8.2 (version A). The coating composition according to the present invention or a comparative coating composition is then applied stress-free in a single application using a rotary atomizer as a wedge with a target layer thickness (layer thickness of the dry material) ranging from 5 microns to 40 microns, according to DIN EN ISO 28199-1, point 8.3. The resulting aqueous base coat layer is dried for 10 minutes at 70°C in a convection oven after a 4-minute ventilation period at 18-23°C.

[0124] The rotor inclination is determined in accordance with DIN EN ISO 28199-3, point 4. The layer thickness is determined from the point where the runner extends 10 mm beyond the bottom edge of the hole, plus the layer thickness at which the inclination of the first runner above the hole can be visually observed.

[0125] 7. Determination of color shift during storage To determine the color shift, the coating composition according to the invention (or a comparative composition) is applied as an aqueous base coat to a primer-coated steel panel measuring 32 x 60 cm before and after storage by double electrostatic application to a total layer thickness (dry layer thickness) of 12 to 17 microns. The first application step is followed by a 3-minute ventilation phase at room temperature (18 to 23 °C). This is followed by a further electrostatic application, and the resulting aqueous lacquer layer is ventilated at room temperature for 10 minutes and then dried in a convection oven at 80 °C for 10 minutes.

[0126] A commercially available two-component clear coat (ProGloss® from BASF Coatings GmbH) with a dry layer thickness of 40-45 μm is applied to the dried aqueous base coat layer. The resulting clear coat is left to stand for 10 minutes at room temperature (18-23°C). It is then cured for a further 20 minutes in a convection oven at 140°C. The correspondingly coated substrate is measured using an X-Rite spectrophotometer (X-Rite MA68 multi-angle spectrophotometer). The surface is illuminated with a light source. Spectral detection in the visible range is carried out at different angles. From the spectral measurements thus obtained, taking into account the standard spectral values ​​and the reflectance spectrum of the light source used, the CIEL * a * b * The color values ​​in the color space can be calculated, where L * Hagane lightness, a * is the red-green value, b *denotes the yellow-blue value (see DIN EN ISO 11664-4 of June 2012). This method is described, for example, in ASTM E2194-12, in particular for coatings containing at least one effect pigment as pigment. The parameter used at this point to quantify the hue shift before and after storage of the sample is the mDE * This is the color distance DE averaged over all detection angles. * (also called Delta E, dE or ΔE) and is described in DIN EN ISO 11664-4 of June 2012.

[0127] 8. Determination of Adhesion Properties To determine the adhesive properties of a coating composition according to the invention (or a comparative composition), a multi-layer coating is prepared according to the following general rules: A water-based basecoat was applied by double air pressure application to a metal substrate measuring 10 x 20 cm, which had been coated with a curable ED coat (CatoGuard® 800, BASF Coatings GmbH), resulting in a total layer thickness (dry layer thickness) of 22-26 μm. A 3-minute airing period was performed at room temperature between the first and second air pressure applications. The resulting water-based basecoat layer was then dried in a convection oven at 70°C for 10 minutes after a 5-minute re-airing period at room temperature. A commercial two-component clearcoat (ProGloss, BASF Coatings GmbH) with a target layer thickness of 40-45 μm was applied to the dried water-based basecoat. It was then cured in a convection oven at 140°C for 20 minutes.

[0128] To evaluate the technical properties, the stone chip adhesion of the multilayer coatings was investigated. For this purpose, a stone impact test was carried out according to DIN EN ISO 20567-1, method B. The resulting damage patterns were also evaluated according to DIN EN ISO 20567-1.

[0129] Furthermore, a steam jet test was carried out according to DIN 55662, method B. The crack (St. Andrew's Cross) was installed with a scratch stylus according to Sikkens (see DIN EN ISO 17872 Annex A). The evaluation of the steam jet test results was carried out according to DIN 55662.

[0130] Additionally, a steam jet test according to DIN 55662, method B (with a St. Andrew's Cross attached to a scratch stylus by Sikkens according to DIN EN ISO 17872 Annex A) was carried out on substrates on which a stone impact test according to DIN EN ISO 20567-1, method B had previously been carried out. The following scale was used for the visual assessment of the damage pattern: KW0 = No change in sample KW1 = slight leaching of existing damage KW2 = Clearly visible washout of existing damage in the paint layer KW3 = complete removal of the lacquer layer in the area of ​​the blast plate KW4 = Complete removal of lacquer layer beyond blasting range KW5 = complete paint layer peeling from substrate.

[0131] 9. Evaluation of appearance before and after exposure to condensation water The course or waviness of the coated substrates is evaluated using a Wavescan measuring device from Byk / Gardner. The coated substrates are prepared as described in point 8 (measurement of adhesive properties).

[0132] To evaluate the appearance, a laser beam is projected onto the surface under test at an angle of 60°, and with the help of a measuring device, lower values ​​are registered in the so-called short wavelength range (0.3-1.2 mm) and the so-called long wavelength range (1.2-12 mm) at a measuring distance of 10 cm (long wavelength = LW, short wavelength = SW; the lower the value, the better the appearance). Furthermore, a characteristic "clarity of image" (DOI) is determined with the help of a measuring device as a measure of the clarity of the image reflected by the surface of the multilayer structure (the higher the value, the better the appearance). Furthermore, the du ("dullness") value is determined (the lower the value, the better the appearance).

[0133] Corresponding investigations were carried out on uncontaminated samples and after condensation contamination. For this purpose, the coated substrates are stored for 10 days in a climate chamber according to the test climate CH in accordance with DIN EN ISO 6270-2 (date: September 2005). The coated substrates are then evaluated for curvature or waviness 2 or 24 hours after removal from the climate chamber. In the following, the term CC test (constant temperature and humidity test) is also used.

[0134] 10. Determining Volume-based Particle Size Distribution The volume-based particle size distribution is determined by centrifugation in an optical centrifuge (LUMiSizer 651 dispersion analyzer) according to ISO 13318. The sample (i.e., aqueous dispersion) was diluted with distilled water to 0.5% solids and stirred at room temperature for 24 hours. The sample was then diluted again with distilled water (sample / water volume ratio 1 / 4). The exact measurement conditions were as follows: PA cuvette with 2 mm path length, triplicate measurements, temperature 25°C, wavelength 410 nm, speed 4000 / min, and 0.5% dilution with water.

[0135] Evaluation: x10, x50, x90 quantiles of volume-based particle size distribution Q3(x). Literature values ​​of density and refractive index (density: 930 kg / m 3 ; refractive index: 1.53) was used to calculate the particle size distribution.

[0136] 11. Melting Point Determination The melting point was determined using DCS. For this purpose, a representative sample of 5 mg was prepared according to DIN EN ISO 11357-1. The analyzer was operated according to DIN EN ISO 11357-1 and the corresponding melting point of the analyte was obtained. [Example]

[0137] The following examples and comparative examples are intended to illustrate the present invention but should not be construed as imposing any limitations thereon.

[0138] Examples and Comparative Examples Unless otherwise stated, in each case, parts are parts by weight and % is % by weight.

[0139] 1. Preparation of Intermediate Products 1.1 Preparation of talcum paste P1 A paste P1 was prepared from 24.0 parts by weight (pbw) of polyester resin (prepared according to Example D of DE 40 09 858 A1, column 16, lines 37-59), 24.9 parts by weight of talcum (Microtalc IT extra, Mondo Minerals BV), 0.4 parts by weight of 2,4,7,9-tetramethyl-5-decynediol, 3.4 parts by weight of butyl diglycol, 1.1 parts by weight of 10% dimethylethanolamine in water and 46.2 parts by weight of distilled water.

[0140] 1.2 Preparation of barium sulfate paste P2 A paste P2 was prepared from 39 parts by weight of a polyurethane dispersion (prepared according to EP 0228003 B2, page 8, lines 6-18), 54 parts by weight of barium sulfate (Blanc fix micro, Sachtleben Chemie GmbH), 3.7 parts by weight of butyl glycol, 0.3 parts by weight of Agitan 282 (Muenzing GmbH) and 3 parts by weight of distilled water.

[0141] 2. Preparation of Polyamide PA1 Polyamide PA1 was prepared by introducing 1650 g of dimerized fatty acid (Pripol® 1012, available from Croda) and xylol (49.6 g) into a 5 L reactor equipped with a water separator under stirring. The mixture was heated to 60°C, and subsequently hexamethylenediamine (232.40 g) was introduced portionwise. The reactor was heated to 170°C and maintained at that temperature until the acid number was less than 63 mg KOH / g. The product was then cooled to 60°C and neutralized with DMEA (160.25 g, meaning 100% neutralization had been reached).

[0142] PA1 had an acid number of 56 mg KOH / g, a solids content of 89%, a number average molecular weight of 1222 g / mol (measured by GPC), and a melting point of 60°C.

[0143] 3. Preparation of Aqueous Polyamide Dispersions 3.1 Preparation of dispersion PAV1a by batch procedure Polyamide PA1 (599.4 g) was introduced into a 5 L reactor under stirring and heated to 90 °C. Distilled water (3550 g) was added dropwise to the molten polyamide under stirring within 2 hours. The reactor was then cooled and the resulting dispersion was discharged. The solids content was 12.7%. The product was a clear, light, opaque mixture. No particles could be detected, i.e. the dispersion can be called a solution (see also Table 1 below).

[0144] 3.2 Preparation of dispersion PAV6a by continuous jet production Polyamine PA1 (120-130 °C) and distilled water (110 °C under pressure) were heated separately. Next, jets of PA1 and water were continuously pumped into a jet reactor (jet size: 300 μm (PA1) and 200 μm (water)). The jets, and thus the polyamide and water, were continuously dispersed (mixed) within the reactor and discharged from the reactor outlet. After the mixing process, the dispersion was rapidly cooled to room temperature. The solids content of the resulting dispersion was adjusted by the pumping speed of the water and polyamide jets, respectively.

[0145] The solids content of dispersion PAV6a was 13% (pump PA1: 242 rpm (100-115 bar), pump water: 1070 rpm (150-160 bar)). The particle size distribution (volume-based) is expressed as the 10th quantile of 69 nm, the 50th quantile of 123 nm, and the 90th quantile of 455 nm.

[0146] Further polyamide dispersions (with different solids content and therefore different water content) were prepared according to the procedures described in 3.1 and 3.2, whereby dispersions PAV2a and PAV5a were prepared according to procedure 3.1, and PAV3a, PAV4a, PAV5a and PAV7a according to procedure 3.2, as summarized in Table 1.

[0147] [Table 1]

[0148] Furthermore, the particle size distribution of commercially available aqueous polyamide dispersions was investigated, as detailed in Table 2.

[0149] [Table 2]

[0150] 4. Preparation of Polyamide Slurry PS Due to the versatility of the aqueous polyamide dispersions described above, various polyamide slurries were prepared. For this purpose, the components listed in Table 3 were mixed in the given order under stirring. After a final step of intensive stirring for 10 minutes, a homogeneous polyamide slurry was formed.

[0151] [Table 3]

[0152] 5. Preparation of aqueous preparations for producing coating compositions PL1 and PL2 The ingredients shown in Table 4 were mixed in the specified order under stirring. After further stirring for 10 minutes, a pH of 8.5 and an applied viscosity of 100 ± 15 mPa·s (1000 s) were prepared using water and diethanolamine. -1 The shear stress was adjusted to 100 MPa (measured with an Anton Paar Rheolab QC / C-LTD80 / QC).

[0153] [Table 4]

[0154] 6. Preparation of the Aqueous Coating Composition Aqueous coating compositions were prepared according to Tables 5.1 and 5.2, whereby the listed ingredients were mixed in the order listed and stirred for 10 minutes.

[0155] [Table 5]

[0156] Aqueous coating compositions WBL11 and WBL12 were also prepared as outlined below (including Table 6). First, the components listed in Table 6 for the "aqueous phase" were mixed in the order indicated. Next, an aluminum premix was formed as outlined in Table 6 and mixed with the aqueous phase. Finally, after stirring for 10 minutes, the aluminum premix was adjusted with water and diethanolamine to a pH of 8.2 and an applied viscosity of 105±15 mPa·s (1000 s). -1 The shear stress was adjusted to 100 MPa (measured with an Anton Paar Rheolab QC / C-LTD80 / QC).

[0157] [Table 6]

[0158] Aqueous coating compositions WBL13-WBL17 were also prepared as outlined below (including Table 7). First, the ingredients listed under "Aqueous Phase" in Table 6 were mixed in the order indicated. Next, an aluminum premix was formed as outlined in Table 6 and mixed with the aqueous phase. Finally, after stirring for 10 minutes, the aluminum premix was adjusted with water and diethanolamine to a pH of 8.0 and an applied viscosity of 85±15 mPa·s (1000 s). -1 The shear stress was adjusted to 100 MPa (measured with an Anton Paar Rheolab QC / C-LTD80 / QC).

[0159] [Table 7]

[0160] Table 8 provides an overview of the complete set of aqueous coating compositions (basecoat formulations) prepared according to the above examples. For better comparability, the compositions are differentiated by inventive and comparative characteristics. Consequently, it is also provided which polyamide dispersions they are made of (directly or via an intermediate, i.e., polyamide slurry). WBLs of the present invention are marked with an asterisk ( * ) is attached.

[0161] [Table 8]

[0162] 7. Performance testing of coating compositions and coating films produced from them The homogeneity and bits of WBL1 to WBL5 and WBL6 to WBL10 were investigated according to the above method, and the results are shown in Tables 9.1 and 9.2.

[0163] [Table 9]

[0164] [Table 10]

[0165] The results showed that the basecoat of the present invention had improved uniformity: no pits were observed in any of the samples examined.

[0166] For WBL11 and WBL12, sagging behavior, storage stability, appearance after CC test, and adhesion were investigated according to the above methods. The results are shown in Tables 9.3 to 9.6.

[0167] [Table 11]

[0168] The maximum coating thickness is 30 μm.

[0169] [Table 12]

[0170] [Table 13]

[0171] [Table 14]

[0172] As a result, it was confirmed that the system WBL12 of the present invention is significantly superior in storage stability, appearance after CC test, and adhesive behavior.

[0173] Next, WBL13 to WBL15 were examined for storage stability, adhesion, sagging behavior, and color shift during storage using the methods described above. The results are shown in Tables 9.7 to 9.10.

[0174] [Table 15]

[0175] [Table 16]

[0176] [Table 17]

[0177] [Table 18]

[0178] The maximum coating thickness for "freshly made" is 30 μm. The maximum coating thickness for "after 2 weeks" is 45 μm.

[0179] The results showed that the system WBL14 of the present invention had significantly better storage stability, adhesive properties, and color shift resistance.

[0180] Finally, WBL16 and WBL17 were investigated for sagging behavior, appearance before and after CC testing, and color shift.

[0181] The results are shown in Tables 9.11 to 9.13.

[0182] [Table 19]

[0183] The maximum coating thickness for "freshly made" is 30 μm. The maximum coating thickness for "after 2 weeks" is 45 μm.

[0184] [Table 20]

[0185] [Table 21]

[0186] This result also shows that the system of the present invention is remarkably superior not only in color shift but also in appearance.

[0187] Overall, the results clearly demonstrate the technical advantages of the coating compositions and basecoats of the present invention when compared to systems that do not meet the requirements regarding particle size distribution of aqueous dispersions of polyamides.

Claims

1. for at least partially coating the optionally coated substrate with a base coat film; at least one binder (A) comprising at least one polymer resin (A1) and optionally at least one crosslinker (A2); at least one pigment (B), and at least one thickener (C), 1. An aqueous coating composition comprising:

1. A coating composition, wherein the thickener (C) is an aqueous dispersion of a polyamide having a volume-based particle size distribution with an x10 quantile of at least 30 nm, an x50 quantile of at least 60 nm, and an x90 quantile of at most 2000 nm.

2. 2. The coating composition of claim 1, wherein the at least one thickener (C) is an aqueous dispersion of polyamide having a volume-based particle size distribution with an x10 quantile of 30 to 120 nm, an x50 quantile of 60 to 300 nm, and an x90 quantile of 200 to 2000 nm.

3. 3. The coating composition according to claim 1 or 2, having a solids content in the range of 0.5 to 15 wt.-%, based on the total weight of the coating composition, for the at least one polyamide in the at least one thickener (C).

4. 3. The coating composition according to claim 1, wherein the polyamide in the thickener (C) has an acid value in the range of 30 to 120 mg of KOH per gram of (C).

5. The polyamide in the thickener (C) is an aliphatic C ３ ~C ２２ Dicarboxylic acids, aliphatic C １４ ~C ２２ At least one polycarboxylic acid selected from the group consisting of polymers, particularly dimers, of monocarboxylic acids, and mixtures thereof, is mixed with at least one aliphatic C ２ ~C １２ 3. The coating composition according to claim 1, which is obtainable by reacting with a diamine.

6. 3. The coating composition according to claim 1, wherein the polyamide in the thickener (C) has a melting point in the range of 50°C to 120°C.

7. 3. The coating composition of claim 1, wherein the pigment (B) comprises at least one effect pigment.

8. 3. The coating composition according to claim 1 or 2, wherein the binder (A) comprises at least one polyurethane, such as a polyurethane-poly(meth)acrylate hybrid polymer, and / or at least one poly(meth)acrylate and / or at least one polyester as at least one polymer resin (A1).

9. 9. The coating composition of claim 8, wherein the binder (A) comprises at least one polyurethane, such as a polyurethane-poly(meth)acrylate hybrid polymer, and at least one poly(meth)acrylate as polymer resins (A1).

10. 10. The coating composition of claim 9, wherein the binder (A) further comprises at least one polyester as polymer resin (A1).

11. 3. The coating composition of claim 1 or 2, comprising at least one further thickener (D) selected from the group consisting of metal silicates, poly(meth)acrylic acid based thickeners, polyurethane based thickeners, polymer waxes, and mixtures thereof.

12. The aqueous dispersion of at least one polyamide as the aqueous dispersion of at least one thickener (C) is prepared by the following continuous production (i) continuously introducing jet streams of water and polyamide into a reactor via inlets therein; (ii) continuously dispersing the jet stream, and thus the water and polyamide, within the reactor; and (iii) continuously discharging the aqueous dispersion thus produced from the reactor through an outlet of the reactor; 3. The coating composition according to claim 1 or 2, wherein the respective aqueous polyamide dispersion is obtained by

13. (I) preparing an aqueous dispersion of at least one thickener (C), which is an aqueous polyamide dispersion having a volume-based particle size distribution with an x10 quantile of at least 30 nm, an x50 quantile of at least 60 nm, and an x90 quantile of at most 2000 nm; (II) mixing the aqueous dispersion of at least one thickener (C) with further components of the coating composition; 10. A method for producing the aqueous coating composition of claim 1, comprising:

14. The step (I) is the following continuous production (i) continuously introducing jet streams of water and polyamide into a reactor via inlets therein; (ii) continuously dispersing the jet stream, and thus the water and polyamide, within the reactor; and (iii) continuously discharging the aqueous dispersion thus produced from the reactor through an outlet of the reactor; to obtain the respective aqueous polyamide dispersion.

15. 10. A method for at least partially coating an optionally coated substrate with a basecoat film, comprising producing said basecoat film using the aqueous coating composition of claim 1.

16. 16. A basecoat film obtainable by at least partially coating at least one optionally coated substrate with the aqueous coating composition of claim 1 or 2 and / or obtainable by the method of claim 15.

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