EP3416754A1

EP3416754A1 - Method for producing a multi-layered coating

Info

Publication number: EP3416754A1
Application number: EP16705526.8A
Authority: EP
Inventors: Cathrin CORTEN; Dirk EIERHOFF; Patrick WILM; Klaus-Juergen KANNGIESSER; Joerg Schwarz
Original assignee: BASF Coatings GmbH
Current assignee: BASF Coatings GmbH
Priority date: 2016-02-19
Filing date: 2016-02-19
Publication date: 2018-12-26
Also published as: KR20180114045A; JP2019511956A; WO2017140380A1; CN108698081A; JP6650047B2; RU2708852C1; US20210205845A1

Abstract

The invention relates to a method for producing a multi-layered coating on a metallic substrate, in which a base coat layer or a plurality of directly consecutive base coat layers are produced directly on a metallic substrate that has been coated with a hardened electrophoretic dip coating, a clear coat layer being produced directly on the one or the uppermost of the plurality of base coat layers, and the one or the plurality of base coat layers and the clear coat layer subsequently being hardened together. The method is characterised in that at least one base coat employed in the production of the base coat layers contains at least one pre-dispersed mixture (vdM), said mixture (vdM) comprising at least one polyamide (P) with an acid value of less than 20 mg KOH/g, at least one polymer resin (H) differing from said polyamide, as well as water and at least one organic solvent.

Description

Process for producing a multicoat paint system

The present invention relates to a process for producing a multicoat paint system in which a basecoat film or several directly successive basecoat films are produced directly on a metallic substrate coated with a cured electrocoating, a clearcoat film is produced directly on one or the uppermost of the multiple basecoat films, and then the one or more basecoat films and the clearcoat film are cured together. In addition, the present invention relates to a multi-layer coating, which was prepared by the process according to the invention.

State of the art

Multicoat paint systems on metallic substrates, for example multicoat paint systems in the automotive industry, are known. As a rule, such multicoat paint systems, when viewed from the metallic substrate, comprise an electrodeposition coating layer, a layer applied directly to the electrodeposition coating layer, usually referred to as surfacer layer, at least one layer containing color and / or effect pigments and usually referred to as basecoat layer and a clearcoat layer.

The basic compositions and functions of the layers mentioned and the coating compositions necessary for the construction of these layers, that is to say electrocoating paints, so-called fillers, coating agents and clearcoats which contain colorants and / or effect pigments known as basecoats, are known. For example, the electrophoretically applied electrodeposition coating layer basically serves to protect the substrate from corrosion. The surfacer layer serves primarily to protect against mechanical stress, such as, for example, falling rocks, and also to fill in unevennesses in the substrate. The next layer, referred to as the basecoat layer, is primarily responsible for the production of aesthetic properties such as color and / or effects such as the flop, while the subsequent clearcoat layer then serves in particular the scratch resistance and the gloss of the multi-layer coating. The production of these multicoat paint systems takes place in the prior art such that initially an electrodeposition paint, in particular a cathodic electrodeposition paint, is applied or deposited electrophoretically on the metallic substrate, for example an automobile body. The metallic substrate can be pretreated differently prior to the deposition of the electrodeposition coating, for example, known conversion coatings such as phosphate coatings, in particular zinc phosphate coatings, can be applied. The deposition process of the electrocoating generally takes place in corresponding electrocoating pools. After application, the coated substrate is removed from the basin, optionally rinsed and flashed and / or intermediately dried, and finally the applied electrodeposition paint is cured. In this case, layer thicknesses of about 15 to 25 micrometers are desired. Subsequently, the so-called filler is applied directly to the cured electrodeposition coating layer, optionally flashed off and / or intermediately dried and then cured. In order for the cured surfacer layer to be able to fulfill the abovementioned objects, layer thicknesses of, for example, 25 to 45 micrometers are desired. Directly onto the cured surfacer layer, a so-called basecoat containing color and / or effect pigments is then applied, optionally flashed off and / or intermediately dried, and a clearcoat applied directly to the basecoat film thus prepared without separate curing. Subsequently, the basecoat film and optionally also previously flashed and / or intermediately dried clearcoat film are cured together (wet-in-wet process). While the cured basecoat film generally has comparatively small layer thicknesses of, for example, 10 to 20 micrometers, layer thicknesses of, for example, 30 to 60 micrometers are desired for the cured clearcoat film in order to achieve the application-technological properties described. The application of filler, basecoat and clearcoat can be carried out, for example, via the application methods of pneumatic and / or electrostatic spray application known to those skilled in the art. Filler and basecoat are now increasingly used for environmental reasons as aqueous coating materials.

Such multicoat paint systems and processes for their preparation are described for example in DE 199 48 004 A1, page 17, line 37, to page 19, line 22, or also in DE 100 43 405 C1, column 3, paragraph [0018], and column 8, paragraph [0052] to column 9, paragraph [0057], in conjunction with column 6, paragraph [0039] to column 8, paragraph [0050 ].

Even though the multicoat paint systems produced in this way can generally meet the requirements of application technology properties and aesthetic profiles set by the automotive industry, the simplification of the described and comparatively complex production process is increasingly becoming the focus of automobile manufacturers for ecological and economic reasons.

Thus, there are approaches in which it is attempted to dispense with the separate curing step of the coating agent applied directly to the cured electrodeposition coating layer (the coating agent referred to as a filler in the standard method described above), if appropriate also to reduce the layer thickness of the coating layer produced from this coating composition , In the specialist world, this coating layer, which is not separately cured, is then often referred to as the basecoat film (and no longer as the filler film) or, in contrast to a second basecoat film applied thereto, is referred to as the first basecoat film. Sometimes even attempts to completely dispense with this coating layer (in which case only a so-called base coat layer is prepared directly on the electrocoating, which is covered with a clear coat without separate curing step, so ultimately also waives a separate curing step). Thus, instead of the separate curing step and an additional final curing step, only a final curing step should be carried out after application of all coating layers applied to the electrodeposition coating layer.

The omission of a separate curing step of the coating agent applied directly to the electrodeposition coating layer is very advantageous from an ecological and economical point of view. Because this leads to energy savings and the entire manufacturing process can of course be much more stringent. Thus, instead of the separate curing step, it is advantageous that the coating layer produced directly on the electrodeposition coating layer is flashed off only at room temperature and / or intermediately dried at elevated temperatures, without curing, which is known to require regularly increased curing temperatures and / or long curing times.

The problem, however, is that in this form of production nowadays often the required application technology and aesthetic properties can not be obtained.

Thus, by dispensing with the separate curing of the coating layer applied directly to the electrodeposition coating layer, for example the first basecoat film, prior to the application of further coating agents, for example a second basecoat material and a clearcoat, unwanted air, solvent and / or moisture inclusions may form may be noticeable in the form of bubbles below the surface of the overall finish and may break during the final cure. The resulting holes in the paint, also called pinholes and digester, lead to a disadvantageous visual appearance. The amount of organic solvent or water produced as a result of the overall structure of the first basecoat film, second basecoat film and clearcoat and the amount of air introduced by the application is too great for the entire amount to escape from the multi-coat finish without a defect during the final curing step. In the case of a conventional manufacturing process as described above, in which the so-called filler layer is baked separately prior to the production of a usually comparatively thin (and therefore containing only comparatively little air, organic solvents and / or water) basecoat, the solution of this problem is of course clear less demanding.

But even in the production of multi-layer coatings, in which the use of the standard process referred to as a filler coating agent is completely dispensed with, that is, systems in which so only a so-called basecoat is applied directly to the cured electrodeposition coating layer, One often encounters the described problems with pinholes and stoves. Because depending on the application and use of the multicoat paint system to be produced, completely dispensing with the coating referred to as filler layer in the standard process generally requires a thicker basecoat than the standard systems in order to obtain the desired properties. In this case too, the total layer thickness of coating layers, which must be cured in the final curing step, is substantially higher than in the standard process.

Also, other relevant properties are not always achieved to a satisfactory extent in the construction of multi-layer coatings over the described method. Thus, for example, the achievement of a high-quality overall impression (appearance), which in particular is influenced by a good course of the coating compositions used, or the minimization of specks is a challenge. The rheological properties of the coating compositions must be appropriately matched to the described process control.

It is generally known to use a wide variety of rheological aids to adjust the rheological properties.

For example, EP 0 877 063 A2 discloses aqueous coating compositions which contain a polyamide, usually employed in aqueous compositions, as a rheology aid, which, owing to its intended use in aqueous systems, is distinguished by a comparatively high acid number of usually greater than 30 mg KOH / g. Aqueous coating compositions which have such polyamides with a comparatively high acid number usually used in aqueous compositions are furthermore known from WO 2009/100938 A1 and EP 2 457 961 A1. However, a disadvantage of the presence of such a polyamide as a rheology aid in aqueous coating compositions is in particular the occurrence of specks in the processing of a corresponding aqueous coating agent in a method as described above. Also known are aqueous coating compositions containing a metal silicate commonly used as a rheology aid in aqueous coating compositions, such as the commercially available metal silicate "Laponite® RD." However, the disadvantage here is the increased occurrence of pinholes and / or poor processing during processing by means of the above described method.

From DE 40 28 386 A1, aqueous coating compositions are known which contain a polyamide as sole rheology aid. The polyamide is added in the preparation of the compositions as such, that is, in particular not in the form of a mixture with other components. Nothing is disclosed of the above-described special production process of multicoat paint systems and related requirements.

The use of polyamides with lower acid numbers per se as rheology aids is known in principle, however, such polyamides are generally used in the prior art in solvent-based (based on organic solvents) coating compositions.

Task and technical solution

An advantage would therefore be a process for the production of multicoat paint systems in which a separate curing step as described above for the coating agent applied directly to the electrodeposition coating can be dispensed with and the multicoat paint system produced nevertheless has excellent application-technological, in particular aesthetic properties. Exactly this task is the present invention.

It was found that the stated objects could be achieved by a novel process for producing a multicoat paint system (M) on a metallic substrate (S) (1) production of a hardened electrodeposition coating layer (E.1) on the metallic substrate (S) by electrophoretic application of an electrodeposition paint (e.1) to the substrate (S) and subsequent hardening of the electrodeposition paint (e.1),

(2) Preparation (2.1) of a basecoat film (B.2.1) or (2.2) of several directly successive basecoat films (B.2.2.x) directly on the cured electrodeposition coating (E.1) by (2.1) applying an aqueous basecoat (b .2.1) directly onto the electrodeposition coating layer (E.1) or (2.2) directly successive application of several basecoats (b.2.2.x) to the electrodeposition coating layer (E.1),

(3) production of a clearcoat film (K) directly on (3.1) the basecoat film (B.2.1) or (3.2) of the topmost basecoat film (B.2.2.x) by applying a clearcoat material (k) directly to (3.1) the basecoat film ( B.2.1) or (3.2) the topmost basecoat layer (B.2.2.X),

(4) joint curing of the (4.1) basecoat film (B.2.1) and the clearcoat film (K) or (4.2) of the basecoat films (B.2.2.x) and the clearcoat film (K), characterized in that the basecoat (b. 2.1) or at least one of the basecoats (b.2.2.x) at least one predispersed mixture (vdM), wherein the mixture (vdM) at least one polyamide (P) having an acid number of less than 20 mg KOH / g, at least one of the Polyamide comprises various polymeric resin (H) and water and at least one organic solvent.

The abovementioned method is also referred to below as the method according to the invention and is accordingly the subject of the present invention. Preferred embodiments of the method according to the invention are given in the description below and in the subclaims.

Furthermore, the present invention is a multi-layer coating, which was prepared by the method according to the invention. The inventive method allows the production of multi-layer coatings waiving a separate curing step of the coating layer produced directly on the electrodeposition coating layer. For better clarity, this coating layer is referred to in the context of the present invention as a basecoat film. Instead of separate curing, this basecoat film is cured together with optionally further basecoat films below the clearcoat film and the clearcoat film together. Nevertheless, result from the application of the method according to the invention multi-layer coatings, which have excellent application technology, in particular aesthetic properties.

In particular, it was surprising that it is possible to obtain the described aesthetic properties, that is positive, precisely by using a polyamide (P) having an acid number of less than 20 mg KOH / g in an aqueous basecoat and its use in the process described above Influences on particular specks, pinholes and flow defects to get. Because it is precisely these polyamides are usually used in solvent-based coating compositions due to their hydrophobic character. However, the solution of the problem only succeeds if the polyamide is used in the form of a predispersed special mixture (vdM) in the preparation of the aqueous basecoat.

Detailed description

First, some terms used in the context of the present invention will be explained.

The application of a coating agent to a substrate or the production of a coating layer on a substrate are as follows. The respective coating agent is applied such that the coating layer produced therefrom is arranged on the substrate, but does not necessarily have to be in direct contact with the substrate. For example, other layers may be arranged between the coating layer and the substrate. For example, in step (1), the cured electrodeposition coating layer (E.1) is formed on the metallic substrate (S), but between the substrate and the substrate Electrocoating layer may be arranged as described below conversion coating such as zinc phosphating.

The same principle applies to the application of a coating agent (b) to a coating layer (A) produced by means of another coating agent (a) or to the production of a coating layer (B) on another coating layer (A). The coating layer (B) does not necessarily have to be in contact with the coating layer (A), it merely has to be arranged above it, that is to say on the side of the coating layer (A) facing away from the substrate.

By contrast, applying a coating agent directly to a substrate or producing a coating layer directly on a substrate is understood as follows. The respective coating agent is applied such that the coating layer produced therefrom is arranged on the substrate and is in direct contact with the substrate. In particular, no other layer is arranged between the coating layer and the substrate.

The same naturally applies to the application of a coating composition (b) directly to a coating layer (A) produced by means of another coating agent (a) or to the production of a coating layer (B) directly on another coating layer (A). In this case, the two coating layers are in direct contact, so they are arranged directly on top of each other. In particular, there is no further layer between the coating layers (A) and (B). Of course, the same principle applies to a direct sequential application of coating compositions or the production of directly successive coating layers.

In the context of the present invention, flash drying, intermediate drying and hardening are to be understood as meaning the term contents familiar to the person skilled in the art in connection with processes for producing multicoat paint systems. Thus, the term bleeding is basically understood to mean the evaporation or evaporation of organic solvents and / or water of a coating agent applied during the production of a coating at usually ambient temperature (ie room temperature), for example 15 to 35 ° C. for a period of for example, 0.5 to 30 minutes. During the flash-off, organic solvents and / or water which are contained in the applied coating agent evaporate. In any case, since the coating material is still flowable directly after application and at the beginning of venting, it can run during the venting process. Because at least one applied by spray application coating agent is usually applied droplet-shaped and not in a homogeneous thickness. However, it is flowable by the organic solvents contained and / or water and can thus form a homogeneous, smooth coating film by the bleeding. At the same time, organic solvents and / or water evaporate successively, so that after the ablation phase, a comparatively smooth coating layer has formed, which contains less water and / or solvent compared to the applied coating composition. However, the coating layer is not yet ready for use after it has been flashed off. It is, for example, no longer flowable, but still soft or sticky, possibly only dried. In particular, the coating layer is not yet cured as described below.

Intermediate drying is therefore also understood to mean the evaporation or evaporation of organic solvents and / or water of a coating agent applied during the production of a coating, usually at a temperature of, for example, 40 to 90 ° C., higher than the ambient temperature, for a duration of, for example, 1 to 60 min. Even with intermediate drying, the applied coating agent will thus lose a proportion of organic solvents and / or water. With respect to a particular coating agent is generally considered that the intermediate drying in comparison to bleeding at, for example, higher temperatures and / or for a longer period of time is done, so compared to bleeding and a higher proportion of organic solvents and / or water from the escaped coating layer escapes. But even the intermediate drying gives no coating layer ready for use Condition, that is, not a cured as described below coating layer. For example, a typical sequence of flash and intermediate drying would be to flash off an applied coating layer for 3 minutes at ambient temperature and then to dry at 60 ° C. for 10 minutes. However, a final distinction between the two terms is neither necessary nor wanted. For the sake of clarity, these terms are used to make it clear that one of the curing described below can be preceded, variable and sequential conditioning a coating layer. In this case, depending on the coating agent, the evaporation temperature and evaporation time, more or less high proportions of the organic solvent contained in the coating agent and / or water evaporate. Optionally, even a proportion of the polymers contained in the coating agent can already be crosslinked or intertwined with one another as a binder as described below. However, both during the drying and during the intermediate drying, no ready-to-use coating layer is obtained, as is the case with the curing described below. As a result, curing is clearly differentiated from flash off and intermediate drying.

Accordingly, hardening of a coating layer is understood to mean the transfer of such a layer into the ready-to-use state, that is to say into a state in which the substrate equipped with the respective coating layer can be transported, stored and used as intended. A cured coating layer is thus no longer particularly soft or sticky, but conditioned as a solid coating film, which no longer substantially changes its properties such as hardness or adhesion to the substrate even upon further exposure to curing conditions as described below.

As is known, coating compositions can basically be cured physically and / or chemically, depending on the constituents contained, such as binders and crosslinking agents. In chemical hardening, thermal-chemical curing and actinic-chemical hardening may be considered. A coating composition may, for example if it is thermally-chemically curable, be self-crosslinking and / or externally-crosslinking. The statement that a coating agent is self-crosslinking and / or externally crosslinking is within the scope of the present invention understand that this coating agent contains polymers (also called polymers) as a binder and optionally crosslinking agents, which can crosslink together accordingly. The underlying mechanisms as well as usable binders and crosslinking agents (film-forming components) are described below.

In the context of the present invention, "physically curable" or the term "physical curing" means the formation of a cured coating layer by release of solvent from polymer solutions or polymer dispersions, the curing being achieved by entanglement of polymer chains. Such coating compositions are generally formulated as one-component coating compositions.

In the context of the present invention, "thermally-chemically curable" or the term "thermal-chemical curing" means the crosslinking of a lacquer layer initiated by chemical reaction of reactive functional groups (formation of a hardened coating layer), the energetic activation of this chemical reaction by thermal energy is possible. In this case, different functional groups which are complementary to one another can react with one another (complementary functional groups) and / or the formation of the hardened layer is based on the reaction of autoreactive groups, that is to say functional groups which react with each other with groups of their type. Examples of suitable complementary reactive functional groups and autoreactive functional groups are known, for example, from German Patent Application DE 199 30 665 A1, page 7, line 28, to page 9, line 24.

This crosslinking can be a self-crosslinking and / or an external crosslinking. If, for example, the complementary reactive functional groups are already present in an organic polymer used as a binder, for example a polyester, a polyurethane or a poly (meth) acrylate, self-crosslinking is present. An external crosslinking is present, for example, when a (first) organic polymer containing certain functional groups, for example hydroxyl groups, with a known crosslinking agent, for example a polyisocyanate and / or a melamine resin, responding. The crosslinking agent thus contains reactive functional groups which are complementary to the reactive functional groups present in the (first) organic polymer used as binder.

In particular, in the case of external crosslinking are the per se known one-component and multi-component systems, in particular two-component systems into consideration.

In thermally-chemically curable one-component systems, the components to be crosslinked, for example organic polymers as binders and crosslinking agents, are present next to one another, that is to say in one component. The prerequisite for this is that the components to be crosslinked only react effectively with one another at elevated temperatures of, for example, above 100 ° C., that is, undergo curing reactions. Otherwise, the components to be crosslinked would have to be stored separately from one another and mixed with one another shortly before application to a substrate, in order to avoid premature, at least proportional, thermochemical curing (compare two-component systems). As an example of a combination, hydroxy-functional polyesters and / or polyurethanes with melamine resins and / or blocked polyisocyanates may be mentioned as crosslinking agents.

In thermally-chemically curable two-component systems, the components to be crosslinked, for example the organic polymers as binders and the crosslinking agents, are present separately from one another in at least two components which are combined only shortly before application. This shape is selected when the components to be crosslinked are effectively reacting at ambient temperatures or slightly elevated temperatures of, for example, 40 to 90 ° C. As an example of a combination, hydroxy-functional polyesters and / or polyurethanes and / or poly (meth) acrylates with free polyisocyanates as crosslinking agents may be mentioned.

It is also possible that an organic polymer has as binder both self-crosslinking and externally crosslinking functional groups and then combined with crosslinking agents. In the context of the present invention, the term "actinic-chemical hardening" or the term "actinic-chemical curing" is to be understood as meaning the hardening using actinic radiation, namely electromagnetic radiation such as near infrared (NIR) and UV radiation, in particular UV radiation, as well as corpuscular radiation such as electron radiation for curing is possible. Curing by UV radiation is usually initiated by free-radical or cationic photoinitiators. Typical actinically curable functional groups are carbon-carbon double bonds, which usually radical photoinitiators are used. The actinic hardening is therefore also based on a chemical crosslinking.

Of course, when curing a chemically curable coating agent is always a physical cure, that is a entanglement of polymer chains occur. The physical hardening can even make up the majority. Nevertheless, such a coating composition, insofar as it contains at least a proportion of film-forming components which are chemically curable, is referred to as chemically curable.

It follows from the above that, depending on the nature of the coating composition and the components contained therein, curing is effected by different mechanisms, which of course also make different conditions necessary during the curing, in particular different curing temperatures and curing times.

In the case of a purely physically curing coating agent, curing preferably takes place between 15 and 90 ° C. over a period of 2 to 48 hours. In this case, the curing of flash-off and / or intermediate drying thus differs possibly only by the duration of the conditioning of the coating layer. A differentiation between flash off and intermediate drying is also not useful. It would be possible, for example, first to ventilate or temporarily dry a coating layer produced by applying a physically curable coating composition at 15 to 35 ° C. for a period of, for example, 0.5 to 30 minutes and then to cure at 50 ° C. for a period of 5 hours. However, at least some of the coating materials to be used in the process according to the invention, that is to say electrodeposition paints, aqueous basecoats and clearcoats, are preferably thermally-chemically curable, more preferably thermally-chemically curable and externally crosslinking.

In principle and in the context of the present invention, the curing of thermally-chemically curable one-component systems preferably takes place at temperatures of 100 to 250 ° C., preferably 100 to 180 ° C. for a period of 5 to 60 minutes, preferably 10 to 45 min is carried out, since these conditions are usually necessary to convert the coating layer by chemical crosslinking reactions in a cured coating layer. Accordingly, a pre-cure buffing and / or intermediate drying phase occurs at lower temperatures and / or for shorter times. For example, in such a case, it may be flashed off at 15 to 35 ° C for a period of, for example, 0.5 to 30 minutes, and / or intermediately dried at a temperature of, for example, 40 to 90 ° C for a period of, for example, 1 to 60 minutes.

Basically, and in the context of the present invention, the curing of thermally-chemically curable two-component systems at temperatures of for example 15 to 90 ° C, in particular 40 to 90 ° C for a period of 5 to 80 minutes, preferably 10 to 50 min can be performed. Accordingly, a pre-cure buffing and / or intermediate drying phase occurs at lower temperatures and / or for shorter times. For example, in such a case it is no longer useful to distinguish between the terms evaporation and intermediate drying. A pre-curing or intermediate drying phase can, for example, take place at 15 to 35 ° C. for a period of, for example, 0.5 to 30 minutes, but at any rate at lower temperatures and / or for shorter times than the subsequent curing.

Of course, this does not exclude that a thermally-chemically curable two-component system is cured at higher temperatures. For example, in the step (4) of the method according to the invention described in more detail below, a basecoat film or several basecoat films together with a clearcoat cured. If both thermally chemically curable one-component and two-component systems are present within the layers, for example a one-component basecoat and a two-component clearcoat, the joint curing is of course determined by the curing conditions necessary for the one-component system.

All temperatures explained in the context of the present invention are understood to mean the temperature of the room in which the coated substrate is located. What is meant is not that the substrate itself must have the appropriate temperature.

The measuring methods to be used in the context of the present invention for the determination of specific parameters can be found in the example section. Unless explicitly stated otherwise, these measurement methods should be used to determine the respective parameter.

If reference is made in the context of the present invention to an official standard without reference to the official period of validity, this naturally includes the version of the standard applicable at the filing date or, if no valid version at that time, the last valid version.

The method according to the invention

In the context of the method according to the invention, a multicoat system is built up on a metallic substrate (S).

Substrates containing or consisting of, for example, iron, aluminum, copper, zinc, magnesium and their alloys, as well as steel in a wide variety of shapes and compositions are generally suitable as metallic substrates (S). Preferred are iron and steel substrates, for example typical iron and steel substrates as used in the automotive industry. The substrates can be shaped as desired, that is, it can be, for example, simple sheets or even complex components such as in particular car bodies and parts thereof. The metallic substrates (S) can be pretreated prior to stage (1) of the process according to the invention in a manner known per se, that is to say for example purified and / or provided with known conversion coatings. A cleaning can be done mechanically, for example by means of wiping, grinding and / or polishing and / or chemically by pickling by etching in acid or alkali baths, for example by means of hydrochloric or sulfuric acid. The cleaning with organic solvents or aqueous cleaners is of course possible. Pretreatment by application of conversion coatings, in particular by means of phosphating and / or chromating, preferably phosphating, can also take place. In any case, the metallic substrates are preferably conversion-coated, in particular phosphated, preferably provided with a zinc phosphating.

In step (1) of the process according to the invention, a hardened electrodeposition coating layer (E.1) is applied to the metallic substrate (S) by electrophoretic application of an electrodeposition paint (e.1) to the substrate (S) and subsequent curing of the electrodeposition paint (e.1). produced.

The electrodeposition paint (e.1) used in step (1) of the process according to the invention may be a cathodic or anodic electrodeposition paint. It is preferably a cathodic electrodeposition paint. Electrocoating paints have long been known to the skilled person. These are aqueous coating materials which must be capable of being electrophoretically applied to a metallic substrate. In any case, they contain anionic or cationic polymers as binders. These polymers contain functional groups that are potentially anionic, that is, that can be converted into anionic groups, for example, carboxylic acid groups, or functional groups that are potentially cationic, that is, that can be converted into cationic groups, for example, amino groups. The conversion into charged groups is usually achieved by the use of appropriate neutralizing agents (organic amines (anionic), organic carboxylic acids such as formic acid (cationic)), which then produce the anionic or cationic polymers. As a rule, and thus preferably additionally, the electrocoating paints contain typical anti-corrosive pigments. The cathodic electrodeposition paints preferred in the context of the invention preferably contain cationic polymers as binders, in particular hydroxy-functional polyetheramines, which preferably have aromatic structural units. Such polymers are generally obtained by reacting corresponding bisphenol-based epoxy resins with amines such as mono- and dialkylamines, alkanolamines and / or dialkylaminoalkylamines. These polymers are used in particular in combination with blocked polyisocyanates known per se. Reference may be made by way of example to the electrodeposition paints described in WO 9833835 A1, WO 931 6139 A1, WO 0102498 A1 and WO 2004018580 A1.

The electrodeposition coating (e.1) is therefore preferably a chemically-thermally curable coating composition, in which case it is in particular externally crosslinking. The electrocoat material (e.1) is preferably a thermally-chemically curable one-component coating composition. Preferably, the electrocoating (e.1) contains a hydroxy-functional epoxy resin as a binder and a fully blocked polyisocyanate as a crosslinking agent. The epoxy resin is preferably cathodic, in particular containing amino groups.

The electrophoretic application of such an electrocoating paint (e.1) taking place within the scope of step (1) of the method according to the invention is also known. The application is electrophoretically. That is, to be coated metallic workpiece is first dipped in a dip containing the paint and an electric DC field is applied between the metallic workpiece and a counter electrode. Thus, the workpiece acts as an electrode which migrates non-volatile constituents of the electrodeposition paint due to the described charge of the polymers used as binders through the electric field to the substrate and deposit on the substrate, whereby an electrodeposition coating layer is formed. For example, in the case of a cathodic electrodeposition paint, the substrate is thus connected as a cathode, where the hydroxide ions formed there by the electrolysis of water neutralize the cationic binder, so that it is deposited on the substrate and forms an electrodeposition coating. It is then an application by the electrophoretic dipping method. After application of the electrodeposition coating (e.1), the coated substrate (S) is removed from the basin, optionally rinsed with, for example, water-based rinsing solutions, then optionally aerated and / or intermediately dried, and finally the applied electrodeposition coating is cured.

The applied electrodeposition paint (e.1) (or the applied, not yet cured electrodeposition coating) is, for example, at 15 to 35 ° C for a period of, for example, 0.5 to 30 minutes and / or at a temperature of preferably 40 to 90 ° C for a period of, for example, 1 to 60 minutes between dried.

The applied to the substrate electrodeposition coating (e.1) (or the applied, not yet cured electrodeposition coating layer) is preferably at temperatures of 100 to 250 ° C, preferably 140 to 220 ° C for a period of 5 to 60 minutes, preferably 10 bis Cured for 45 minutes, whereby the cured electrodeposition coating layer (E.1) is produced.

The specified flash off, intermediate drying and curing conditions apply in particular to the preferred case that the electrodeposition coating (e.1) is a chemically-thermally curable one-component coating composition as described above. However, this does not exclude that the electrodeposition coating is a curable coating agent in other ways and / or other Ablüft-, Zwischentrocknungs- and curing conditions are used.

The layer thickness of the cured electrodeposition coating layer is, for example, 10 to 40 micrometers, preferably 15 to 25 micrometers. All layer thicknesses specified in the context of the present invention are understood as dry layer thicknesses. It is therefore the layer thickness of the respective cured layer. If, therefore, it is stated that a lacquer is applied in a certain layer thickness, it is to be understood that the lacquer is applied in such a way that the said layer thickness results after hardening.

In step (2) of the process according to the invention (2.1) a basecoat film (B.2.1) is prepared or (2.2) there are several directly successive Basecoat layers (B.2.2.x) produced. The layers are produced by applying (2.1) an aqueous basecoat material (also called aqueous basecoat) (b.2.1) directly to the cured electrodeposition coating layer (E.1) or (2.2) applying several basecoats in succession (b.2.2.x). on the cured electrodeposition coating (E.1).

The directly successive application of several basecoats (b.2.2.x) to the cured electrodeposition coating layer (E.1) is thus understood to mean that first a first basecoat is applied directly to the electrodeposition coat and then a second basecoat is applied directly to the layer of the first base coat is applied. An optionally third basecoat is then applied directly to the layer of the second basecoat. This process can then be repeated analogously for further basecoats (ie a fourth, fifth, etc. basecoat).

The basecoat film (B.2.1) or the first basecoat film (B.2.2.x) is thus arranged directly on the cured electrodeposition coating (E.1) after production.

The terms basecoat and basecoat film in relation to the coating agents and coating layers applied in step (2) of the process of the invention are used for the sake of clarity. The basecoat films (B.2.1) and (B.2.2.x) are not cured separately, but cured together with the clearcoat. Curing thus takes place analogously to the curing of so-called basecoats used in the standard method described in the introduction. In particular, the coating compositions used in stage (2) of the process according to the invention are not hardened separately, as are the coating compositions designated as fillers in the standard process.

The aqueous basecoat (b.2.1) used in step (2.1) is described in detail below. In a first preferred embodiment, however, it is at least chemically-thermally curable, particularly preferably externally crosslinking. In this case, the basecoat (b.2.1) is preferably a one-component coating agent. The basecoat material (b.2.1) preferably contains a combination of at least one hydroxyl-functional polymer as binder selected from the group consisting of polyacrylates, polyurethanes, polyesters and copolymers of the abovementioned Polymers, for example polyurethane polyacrylates, and at least one melamine resin as a crosslinking agent.

Depending on the field of application equally possible and thus a second preferred embodiment, it is, however, to use basecoats (b.2.1), which only small amounts of less than 5 wt .-%, preferably less than 2.5 wt .-%, based on the Total weight of the basecoat, on crosslinking agents such as melamine resins in particular. Again preferred in this embodiment is that no crosslinking agents are included. Nevertheless, an excellent quality of the overall structure is achieved. An advantage of the non-use of crosslinking agents and the consequently lower complexity of the paint lies in the increase of formulation freedom for the basecoat. Also storage stability may be better due to the avoidance of possible reactions of the reactive components.

The basecoat (b.2.1) can be applied by the methods known to those skilled in the art for the application of liquid coating compositions, for example by dipping, knife coating, spraying, rolling or the like. Preferably, spray application methods are used, such as compressed air spraying (pneumatic application), airless spraying, high rotation, electrostatic spray application (ESTA), optionally combined with hot spray application such as hot air (hot spraying). Most preferably, the basecoat (b.2.1) is applied via the pneumatic spray application or the electrostatic spray application. The application of the basecoat (b.2.1) thus produces a basecoat film (B.2.1), ie a layer of the basecoat (b.2.1) applied directly to the electrodeposition coating (E.1).

The applied basecoat (b.2.1) or the corresponding basecoat film (B.2.1) is flashed off after application, for example, at 15 to 35 ° C for a period of, for example, 0.5 to 30 minutes and / or at a temperature of preferably 40 to 90 ° C for a period of, for example, 1 to 60 minutes between dried. Preference is first vented at 15 to 35 ° C for a period of 0.5 to 30 min and then inter-dried at 40 to 90 ° C for a period of, for example, 1 to 60 min. The described Ablüft- and Intermediate drying conditions apply in particular to the preferred case that the basecoat (b.2.1) is a chemically-thermally curable one-component coating composition. However, this does not exclude that the basecoat (b.2.1) is a curable coating material in other ways and / or other ablating and / or intermediate drying conditions are used.

The basecoat film (B.2.1) is not cured within step (2) of the process according to the invention, that is preferably not exposed to temperatures above 100 ° C. for a period of more than 1 minute, especially preferably not at temperatures above 100 ° C. exposed. This results clearly and directly from the below described step (4) of the method according to the invention. Since the basecoat film is only cured in stage (4), it can not be cured in stage (2), because then curing in stage (4) would no longer be possible.

The aqueous basecoats (b.2.2.x) used in step (2.2) of the process according to the invention are also described in detail below. In a first preferred embodiment, at least one of the basecoats used in step (2.2) is in any case chemically-thermally curable, in particular preferably externally crosslinking. Again, this applies to all basecoats (b.2.2.x). In this case, at least one basecoat (b.2.2.x) is preferably a one-component coating composition, and this is more preferably the case for all basecoats (b.2.2.x). At least one of the basecoats (b.2.2.x) preferably contains a combination of at least one hydroxy-functional polymer as binder selected from the group consisting of polyacrylates, polyurethanes, polyesters and copolymers of said polymers, for example polyurethane polyacrylates, and at least one melamine resin crosslinking agent. Again, this applies to all basecoats (b.2.2.x).

Depending on the field of application, it is equally possible and thus likewise a preferred embodiment to use at least one basecoat (b.2.2.x) which only contains small amounts of less than 5% by weight, preferably less than 2.5% by weight. based on the total weight of the basecoat, on crosslinking agents such as in particular melamine resins. Again preferred in this embodiment is that no crosslinking agents are included. Prefers the above applies to all basecoats used (b.2.2.x). Nevertheless, an excellent quality of the overall structure is achieved. Advantages are again formulation freedom and storage stability.

The basecoats (b.2.2.x) can be applied by the methods known to those skilled in the art for the application of liquid coating compositions, for example by dipping, knife coating, spraying, rolling or the like. Preferably, spray application methods are used, such as compressed air spraying (pneumatic application), airless spraying, high rotation, electrostatic spray application (ESTA), optionally combined with hot spray application such as hot air (hot spraying). Most preferably, the basecoats (b.2.2.x) are applied via the pneumatic spray application and / or the electrostatic spray application.

Within the scope of step (2.2) of the process according to the invention, the following designation is appropriate. The basecoats and basecoats are generally characterized by (b.2.2.x) and (B.2.2.x), while in naming the specific individual basecoats and basecoats, the x can be replaced by correspondingly appropriate other letters.

The first basecoat and the first basecoat film can be labeled a, the topmost basecoat and the topmost basecoat film can be labeled z. These two basecoats or basecoats are present in the stage (2.2) in any case. Optionally interposed layers may be consecutively labeled b, c, d and so on.

By applying the first basecoat material (b.2.2.a), a basecoat film (B.2.2.a) is thus produced directly on the cured electrodeposition paint film (E.1). The at least one further basecoat film (B.2.2.x) is then prepared directly on the basecoat film (B.2.2.a). If several further basecoat films (B.2.2.x) are produced, these are prepared directly in succession. For example, exactly one more base coat layer (B.2.2.x) can be produced, which then directly in the finally produced multicoat paint system is arranged below the clearcoat layer (K) and thus can be referred to as basecoat film (B.2.2.Z) (see also Figure 2). It is also possible, for example, for two further basecoat films (B.2.2.x) to be prepared, in which case the film produced directly on the basecoat film (B.2.2.a) is (B.2.2.b) and finally directly below the clearcoat film (K) layer can again be referred to as (B.2.2.z) (see also Figure 3).

The basecoats (b.2.2.x) can be identical or different. It is also possible to produce several basecoat films (B.2.2.x) with the same basecoat and one or more further basecoat films (B.2.2.x) with one or more other basecoats.

The applied basecoats (b.2.2.x) are usually flashed off on their own and / or with each other and / or inter-dried. Preference is also in the context of stage (2.2) at 15 to 35 ° C for a period of 0.5 to 30 min and flashed at 40 to 90 ° C for a period of, for example, 1 to 60 minutes between dried. The sequence of flash-offs and / or intermediate drying of one or more base coat layers (B.2.2.x) can be adapted depending on the requirements of the individual case. The above-described preferred stripping and intermediate drying conditions apply in particular to the preferred case that at least one basecoat (b.2.2.x), preferably all basecoats (b.2.2.x) are chemically-thermally curable one-component coating compositions. However, this does not rule out that the basecoats (b.2.2.x) are curable coating agents in other ways and / or that other ablating and / or intermediate drying conditions are used.

If a first basecoat film is prepared by applying a first basecoat and another basecoat film by applying the same basecoat, then obviously both layers are based on the same basecoat. However, the application is obviously carried out in two stages, so that the corresponding basecoat in the sense of the method according to the invention corresponds to a first basecoat (b.2.2.a) and another basecoat (b.2.2.z). The described construction is often also referred to as a single-layer basecoat layer structure produced in two jobs. Since, however, due to the technical conditions in a paint shop between the first job and the second job, a certain period of time always elapses, during which the substrate, for example the automobile body, is conditioned at, for example, 15 to 35 ° C. and thus vented, the characterization of this structure as a two-layer basecoat construction is formally more distinct. The described process control is thus assigned to the second variant of the method according to the invention.

Some preferred variants of the basecoat layer sequences of the basecoats (b.2.2.x) are explained as follows.

It is possible to produce a first basecoat film by, for example, electrostatic spray application (ESTA) or pneumatic application of a first basecoat directly on the cured electrodeposition coating, to vent and / or intermediate dry as described above and then to apply a second basecoat film directly by applying a second basecoat different from the first basecoat manufacture. The second basecoat can also be applied by electrostatic spray application or by pneumatic application, whereby a second basecoat film is produced directly on the first basecoat film. Of course, between and / or after the orders, it is possible to ventilate again and / or to dry them off. This variant of step (2.2) is preferably selected when first a color-preparing basecoat layer as described in more detail below is to be prepared directly on the electrodeposition coat layer and then a basecoat layer having a color and / or effect as described in greater detail below is produced directly on the first basecoat film shall be. The first basecoat film is then based on the paint-primer basecoat, the second basecoat film on the color and / or effect basecoat. It is also possible, for example, to apply this second basecoat material in two stages as described above, whereby two further, directly successive basecoat films are then formed directly on the first basecoat film, both based on the same basecoat.

It is also possible to produce three basecoat films directly following one another directly on the cured electrodeposition coating layer, the basecoat films on based on three different basecoats. For example, a color-preparing basecoat film, a further coat based on a color and / or effect basecoat and a further coat based on a second color and / or effect basecoat can be prepared. Between and / or after the individual and / or after all three orders can be ventilated again and / or intermediately dried.

Thus, in the context of the present invention, preferred embodiments comprise that two or three basecoat films are produced in stage (2.2) of the process according to the invention. It is then preferred that the basecoat layer prepared directly on the cured electrodeposition coating layer is based on a color-preparing basecoat. The second and optionally present third layer are based either on one and the same color and / or effect basecoat or on a first color and / or effect basecoat and a different second color and / or effect basecoat.

The basecoat films (B.2.2.x) are not cured within stage (2) of the process according to the invention, that is to say preferably not exposed to temperatures above 100 ° C. for a period of more than 1 minute, preferably not temperatures above 100 ° C. C exposed. This results clearly and directly from the below described step (4) of the method according to the invention. Since the basecoat films are only cured in stage (4), they can not be cured in stage (2), because then curing in stage (4) would no longer be possible.

The application of the basecoats (b.2.1) and (b.2.2.x) takes place in such a way that the basecoat film (B.2.1) and the individual basecoat films (B.2.2.x) have a layer thickness after curing in step (4) of, for example, 5 to 50 micrometers, preferably 6 to 40 micrometers, particularly preferably 7 to 35 micrometers. In stage (2.1), it is preferred to produce higher layer thicknesses of 15 to 50 micrometers, preferably 20 to 45 micrometers. In step (2.2), the individual basecoat films have rather comparatively lower layer thicknesses, the overall structure then again having layer thicknesses which are of the order of magnitude of one basecoat film (B.2.1). lie. For example, in the case of two basecoat films, the first basecoat film (B.2.2.a) preferably has film thicknesses of 5 to 35, in particular 10 to 30 micrometers, the second basecoat film (B.2.2.z) preferably film thicknesses of 5 to 35 micrometers, in particular 10 to 30 micrometers, the total layer thickness does not exceed 50 microns.

In step (3) of the process according to the invention, a clearcoat film (K) is prepared directly on (3.1) the basecoat film (B.2.1) or (3.2) of the topmost basecoat film (B.2.2.z). This preparation is carried out by appropriate application of a clearcoat (k).

The clearcoat (k) may be a transparent coating agent known per se to the person skilled in the art in this sense. Under transparent is to be understood that a layer formed with the coating agent is not color-covering, but is constituted so that the color of the underlying base paint assembly is visible. As is known, however, this does not exclude that a clearcoat in minor amounts may also contain pigments which may, for example, support the color depth of the overall structure.

These are aqueous or solvent-containing transparent coating compositions which may be formulated both as one-component and as two-component or multi-component coating compositions. Also suitable are powder slurry clearcoats. Preference is given to solvent-based clearcoats.

The clearcoats (k) used can in particular be thermally-chemically and / or chemically-actinically curable. In particular, they are thermally-chemically curable and externally crosslinking.

The clearcoats therefore usually and preferably contain at least one (first) polymer as binder with functional groups and at least one crosslinker with a functionality complementary to the functional groups of the binder. At least one hydroxy-functional poly (meth) acrylate polymer is preferably used as the binder and a free polyisocyanate as the crosslinking agent. Suitable clearcoats are described, for example, in WO 2006042585 A1, WO 2009077182 A1 or WO 2008074490 A1.

The clearcoat (k) is applied by the methods known to those skilled in the application of liquid coating compositions, for example by dipping, knife coating, spraying, rolling or the like. Preferably, spray application methods are used, such as compressed air spraying (pneumatic application), and electrostatic spray application (ESTA).

The clearcoat (k) or the corresponding clearcoat film (K) is preferably flashed after the application at 15 to 35 ° C for a period of 0.5 to 30 minutes or intermediate dried. Such ablating or intermediate drying conditions apply in particular to the preferred case that the clearcoat (k) is a chemically-thermally curable two-component coating composition. However, this does not exclude that the clearcoat (k) is a curable coating agent in other ways and / or other flash or intermediate drying conditions are used.

The application of the clearcoat material (k) takes place in such a way that the layer thickness of the clearcoat layer after curing in step (4) has a layer thickness of, for example, 15 to 80 micrometers, preferably 20 to 65 micrometers, particularly preferably 25 to 60 micrometers.

Of course, within the scope of the process according to the invention, it is not excluded that after the application of the clearcoat (k) further coating agents, for example further clearcoats, are applied and in this way further coating layers, for example further clearcoat films, are produced. Such further coating layers are then cured, for example, also in the step (4) described below. However, preferably only one clearcoat (k) is applied and then cured as described in step (4). In stage (4) of the process according to the invention, a joint curing of the (4.1) basecoat film (B.2.1) and the clearcoat film (K) or (4.2) of the basecoat films (B.2.2.x) and the clearcoat film (K) takes place.

The joint curing is preferably carried out at temperatures of 100 to 250 ° C, preferably 100 to 180 ° C for a period of 5 to 60 minutes, preferably 10 to 45 min. Such curing conditions apply in particular to the preferred case that the basecoat film (B.2.1) or at least one of the basecoat films (B.2.2.x), preferably all basecoat films (B.2.2.x) are based on a chemically-thermally curable one-component coating composition , As described above, such conditions are usually required to achieve curing of such a one-component coating composition as described above. If, for example, the clearcoat material (k) is also a chemically-thermally curable one-component coating composition, the corresponding clearcoat film (K) is of course also cured under these conditions. The same obviously applies to the preferred case that the clearcoat (k) is a two-component chemical-thermally curable coating agent.

However, the above does not exclude that the basecoats (b.2.1) and (b.2.2.x) and the clearcoats (k) are otherwise curable coating agents and / or other curing conditions are used.

After completion of step (4) of the process according to the invention, a multicoat system according to the invention results (see also FIGS. 1 to 3).

The basecoat materials to be used according to the invention

The basecoat (b.2.1) contains a special pre-dispersed mixture (vdM). This mixture contains at least one polyamide (P) having an acid number of less than 20 mg KOH / g, at least one polymeric resin other than the polyamide (H), and water and at least one organic solvent. The components mentioned are described below. The mixture (vdM) is predispersed. In addition, the basecoat (b.2.1) contains this predispersed mixture. This means that the components which the mixture (vdM) should contain after its completion, are dispersed to the same mixture before the mixture is added as such in the context of the preparation of the basecoat. It is therefore essential to the invention that the mixture (vdM) is added as such. Thus, the phrase "the base coat contains the predispersed blend" is synonymous with the phrase "the pre-dispersed blend is used as such in the manufacture of the base coat".

Preparation of the basecoat (b.2.1) thus comprises the following steps: (i) dispersing the components which the mixture (vdM) is to contain before these components are brought into contact with the further constituents of the basecoat (ie predispersion). (ii) addition of the predispersed mixture (vdM) to the otherwise finished basecoat (b.2.1) or presentation of the mixture (vdM) and addition of the further constituents of the basecoat (b.2.1) or addition of the mixture (vdM) to a part of the other Components of the basecoat (b.2.1) and addition of the remaining part of the other constituents of the basecoat (b.2.1).

The term dispersion (or predispersion) is to be understood as follows based on the expert knowledge familiar to the person skilled in the art. It is the conversion of a mixture of different components, at least some of which are not completely miscible with each other and thus form different phases when simply combined, in a macroscopically homogenized form. The term dispersion is understood as a generic term for the homogenization of immiscible phases, that is, for example, includes solid-liquid and liquid-liquid systems.

Of course, depending on the components contained, after dispersing, a certain microscopic phase separation may or may not be present in the mixture. For in addition to a fundamentally possible molecularly dissolved character of a mixture, this may for example also have emulsion character. The terms macro- and microscopic stand here obviously for a visible with the eye or just not visible phase separation or homogenization.

How a dispersion has to be carried out in an individual case is known and can optionally be determined by simple targeted experiments (see also examples). As a rule, dispersion takes place by introduction of energy into a mixing system, as a result of which the droplets of the different phases are successively reduced and thus the interface between the two phases is successively increased. Overcoming the interfacial tension or creating an enlarged interface requires energy. This energy is regularly introduced mechanically, in particular via shear forces. The introduction of the shear forces takes place regularly via the stirring of the system, for example in typical stirring units such as a dissolver.

Typically, good dispersion is achieved when stirring speed and rate of addition and addition of the components are adjusted so that even a temporary macroscopic phase separation does not occur, but within the system a macroscopically homogenized form over the entire production time. This is therefore preferred within the scope of predispersing the mixture (vdM). Even if a certain phase separation can take place after storage taking place after the dispersion, the system can easily be stirred up again into a homogeneous mold. The dispersing preferably takes place in such a way that a torus-like flow pattern is established, that is to say a so-called donut effect (donut effect) is observed. This term is known to the person skilled in the art.

A predispersion or the preparation of a predispersed mixture can also be carried out, for example, by adding typical auxiliaries (additives). Mention may be made here in particular of further typical surface-active additives (emulsifiers) described in more detail below. The use of such additives is preferred in the context of the present invention. Also possible the use of defoamers known per se, which can suppress foaming that is possible due to the introduction of energy.

In any case, two components of the mixture (vdM) are the polyamide (P) and water. The polyamide is not soluble in water, especially because of its low acid number. For this reason, it can not be converted into a macroscopically homogeneous mixture (vdM) with water without the described predispersion. Accordingly, the polyamide (P) as such is not to be effectively integrated into the aqueous basecoat (b.2.1). A direct addition in the production of the basecoat leads to incompatibilities, which lead to, for example, specks in the coating finally produced. All the more surprising was that the addition in the form of the predispersed mixture leads to such excellent aesthetic properties of the resulting multi-layer coating. Thus, the polyamide provided per se for coating compositions based on organic solvents shows an excellent effect as rheological aids in the systems according to the invention which are based on water-based coating agents.

It is believed that the polymeric resin (H) and the organic solvents, as components of the mixture, have a dispersing action, thus assisting or even facilitating predispersion. Of course, this effect can be supported again by the emulsifiers already described above.

The predispersing of the mixture (vdM) is preferably carried out at a temperature in the range of 15 to 30 ° C over a period of 5 to 60 minutes, preferably over a period of 5 to 30 minutes. The dispersion can be carried out by means of commercially available devices, in particular dissolvers, for example with the device "Dispermat® LC30" from VWA-Getzmann, Germany Such devices usually have a stirring disk (toothed disk) in a stirred container the diameter of the stirring disk to the diameter of the stirred container in a range of 1: 1, 1 to 1: 2.5. Preferably, the peripheral speed of the stirring disk in carrying out the predispersion in a range of 15 to 25 m / s, particularly preferably 15 to 20 m / s The filling height of the stirred tank is preferably in a range of 60 up to 90%, based on the total height of the stirred tank. Preferably, the diameter of the stirring disc is greater than the distance of the stirring disc to the bottom of the stirred container.

The mixture (vdM) may contain varying amounts and types of polyamides (P), polymeric resins (H) and organic solvents, as well as varying amounts of water. The components can be easily matched to one another by a person skilled in the art in order then to obtain a macroscopically homogeneous (that is, predispersed) mixture. It is advantageous, for example, to use as the polymeric resin (H) such that should be integrated into the aqueous basecoat as a binder or crosslinking agent anyway. In this way, a higher freedom of formulation is gained.

The polyamide (P) has an acid number of less than 20 mg KOH per g. Preferably, the polyamide (P) has an acid number of less than 15 mg KOH per g, more preferably less than 10 mg KOH per g, most preferably less than 8 mg KOH per g and even more preferably <7 mg KOH per g, on.

Polyamide (P) preferably has an acid number in a range from 0 to less than 20.0 mg KOH per g, more preferably in a range from 0.1 to less than 15.0 mg KOH per g, most preferably in a range from 0 , 1 to less than 10.0 mg KOH per g, and more preferably in a range of 0.1 to less than 8.0 mg KOH per g. In a further preferred embodiment, the polyamide (P) has an acid number in a range from 0.1 to less than 10 mg KOH per g, more preferably in a range from 0.1 to 9 mg or from 0.5 to 9 mg KOH per g, most preferably in a range from 0.1 to 8 mg or from 0.5 to 8 mg KOH per g, more preferably in a range from 0.1 to <7 mg or from 0.5 to <7 mg KOH per g. The acid number is determined according to the method described below.

Any conventional polyamide known to those skilled in the art can be used as long as this polyamide has an acid number of less than 20 mg KOH per g. The corresponding polyamide may be a polyamide homo- or copolymer act. It is also possible to use a mixture of two or more different polyamides (P).

The polyamide (P) preferably has an amine number of less than 9 mg KOH per g, particularly preferably less than 8 mg KOH per g, most preferably of <7 mg KOH per g. Preferably, the polyamide used as the polymeric resin (P1) has an amine number in a range of 0.1 to less than 10 mg KOH per g, more preferably in a range of 0.1 to 9 mg, or from 0.5 to 9 mg KOH per g, most preferably in a range from 0.1 to 8 mg or from 0.5 to 8 mg KOH per g, more preferably in a range from 0.1 to <7 mg or from 0.5 to <7 mg KOH per g. The person skilled in the art is familiar with determination methods for determining the amine number. Preferably, the amine number is determined according to DIN 1 6945 (date: March 1989).

Preferably, the polyamide (P) has a number average molecular weight in a range of 100 g / mol to 5,000 g / mol, more preferably in a range of 150 g / mol to 4,000 g / mol, most preferably in a range of 200 g / mol to 3,000 g / mol, more preferably in a range of 250 g / mol to 2,000 g / mol, most preferably in a range of 400 g / mol to 1,500 g / mol Methods for determining the number average molecular weight known. The determination of the number average molecular weight is carried out according to the method described below.

Preferably, the polyamide (P) is obtainable by reacting at least one polycarboxylic acid (C1a) with at least one polyamine (C1b), optionally in the presence of at least one monocarboxylic acid, in particular at least one C12-C24 monocarboxylic acid, and / or at least one monoamine, for example a C2-Ci2 monoamine.

Preferably, the polyamide (P) is obtainable by reacting at least one polycarboxylic acid (C1a) selected from the group consisting of aliphatic C3-C22 dicarboxylic acids, polymers such as dimers and trimers of aliphatic C12-C24 monocarboxylic acids, and mixtures thereof, with at least one aliphatic C2-C12 diamine (C1b). Preferably, the reaction of at least one polycarboxylic acid (C1a) and at least one polyamine (C1b) is carried out in a preferably organic solvent.

Preferably, polyamide (P) is obtainable by reacting at least one polycarboxylic acid (C1a), preferably at least one polycarboxylic acid selected from the group consisting of aliphatic C3-C22 dicarboxylic acids, polymers such as dimers and trimers of aliphatic Ci2-C24 monocarboxylic acids, and mixtures thereof , with at least one polyamine (C1 b), preferably with at least one aliphatic C2-Ci2-diamine (C1 b), wherein the reaction product then obtained is optionally subsequently reacted with at least one monoamine and / or a monocarboxylic acid, thereby the acid number and optionally also adjust the amine number.

Polyamides (P) are commercially available. Examples which may be mentioned are the commercially available products Thixatrol® P220X-MF, Disparlon® A6900-20X, Disparlon® A650-20X, Disparlon® A670-20M, Disparlon F-9030, Luvotix® AB, Luvotix® PA 20 XA, Luvotix® R-RF , Luvotix® HT-SF, Luvotix® HAT 400, Luvotix® HT, Troythix® 250 XF, Byk-430, and Byk-431.

Suitable polymeric resins (H) are the resins known to the person skilled in the art in this connection. Depending on the individual case, it may be suitable for the relevant (co) polymers of ethylenically unsaturated monomers, polyaddition resins and / or polycondensation resins. Examples of suitable (co) polymers are (meth) acrylate (co) polymers or partially saponified polyvinyl esters, in particular (meth) acrylate copolymers. Examples of suitable polyaddition resins and / or polycondensation resins are polyesters, alkyds, polyurethanes, polylactones, polycarbonates, polyethers, epoxy resins, epoxy resin-amine adducts, amino resins such as melamine resins, polyureas, polyamides, polyimides, polyester-polyurethanes, polyether-polyurethanes or polyester-polyethers. polyurethanes. Depending on the individual case, the resin component and its proportion of the mixture (vdM) can easily be matched by the person skilled in the art to the further components and their proportions, in order then to obtain a macroscopically homogeneous (that is, predispersed) mixture. Preferred polymeric resins (H) are polyesters, especially those having an acid number in a range of 20 to 50 mg KOH per g and an OH number in a range of 20 to 300 mg KOH per g.

The polyesters particularly preferably have an acid number in a range from 20 to 45 mg KOH per g, very particularly preferably in a range from 25 to 40 mg KOH per g, particularly preferably in a range from 30 to 38 mg KOH per g, on.

The polyesters particularly preferably have an OH number in a range from 25 to 250 mg KOH per g, very particularly preferably in a range from 25 to 200 mg KOH per g, particularly preferably in a range from 25 to 150 mg KOH per g or in a range of 30 to 120 mg KOH per g, on. The determination of the OH number is carried out according to the method described below.

The polyesters preferably have a number-average molecular weight in a range from 500 g / mol to 100 000 g / mol, more preferably in a range from 700 g / mol to 90 000 g / mol, very particularly preferably in a range of 1000 g / mol to 80 000 g / mol, more preferably in a range of 1000 g / mol to 60 000 g / mol or in a range of 2000 g / mol to 60 000 g / mol or in a range of 2000 g / mol to 50,000 g / mol, most preferably in a range of 2,000 g / mol to 10,000 g / mol or in a range of 2,000 g / mol to 6,000 g / mol.

In a preferred embodiment, the polyester is at least obtainable by reacting at least one polymerized aliphatic C 12-24 monocarboxylic acid with at least one diol and / or polyol. The corresponding polyester may be a polyester homo- or copolymer. In the context of the present invention, the term "at least available" is understood to mean that, in addition to the at least one polymerized aliphatic C 12 -C 24 -monocarboxylic acid and the at least one diol and / or polyol, further starting components are optionally used to prepare the polyester (P2) For example, at least one C12-C24 aliphatic monocarboxylic acid and / or at least one dicarboxylic acid and / or at least one a tricarboxylic acid selected from the group consisting of aliphatic C3-C12 dicarboxylic acids, cycloaliphatic C5-C12 dicarboxylic acids, aromatic C8-C12 dicarboxylic acids, aliphatic C5-C12 tricarboxylic acids, cycloaliphatic C6-C12 tricarboxylic acids and aromatic C9-C12 tricarboxylic acids. Also to be mentioned are lactones or hydroxycarboxylic acids.

For the purposes of the present invention, the term "polymerized aliphatic C 12-24 monocarboxylic acid" is preferably understood as meaning a polymer, in particular a dimer and / or trimer of an aliphatic C 12-24 monocarboxylic acid.

Also skilled in the art are preparation processes for the preparation of polymers, especially dimers and trimers, of aliphatic C 12-24 monocarboxylic acids, i. to provide polymerized aliphatic Ci2-C24 monocarboxylic acids, such as dimerized, trimerized and / or higher polymerized, in particular dimerized and / or trimerized, aliphatic C12-C24 monocarboxylic known, for example from DE 25 06 21 1 A1, US 2,793,219 A and US Pat. No. 2,955,121 A. The polymerized aliphatic C.sub.14-C.sub.22 monocarboxylic acids may optionally be monosubstituted or polysubstituted, for example, twice, three times, four times or five times, preferably with at least one substituent selected from the group consisting of OH, O-Ci-4-aliphatic Radicals, = O, NH 2, NH (Ci-4-aliphatic radicals), N (Ci-4-aliphatic radicals), wherein the substitution can take place on the same or different carbon atoms. As starting material for the preparation of such polymerized aliphatic C12-C24 monocarboxylic acids at least monounsaturated aliphatic C12-C24 monocarboxylic acids are used. The resulting polymerized as dimerized and trimerized aliphatic Ci2-C24 monocarboxylic acids can be separated from each other by distillation and also in each case from higher-value polymerization and optionally subjected to further reaction reactions such as hydrogenation.

Preferably, the at least one used for preparing the polyester polymerized aliphatic Ci2-C24 monocarboxylic acid is a dimerized and / or trimerized, especially at least one dimerized, Ci2-C24 monocarboxylic acid. A dimerized monocarboxylic acid is therefore in particular a dicarboxylic acid.

Polymerized, especially dimerized and trimerized C12-C24 monocarboxylic acids are commercially available. Examples of commercially available dimerized fatty acids are the products Empol 1003, Empol 1005, Empol 1008, Empol 1012, Empol 101 6, Empol 1026, Empol 1028, Empol 1061, Empol 1062, Pripol 1006, Pripol 1009, Pripol 1012, Pripol 1013, Pripol 1017 Pripol 1022, Pripol 1025, Pripol 1027 from Croda and, for commercially available trimerized fatty acids, the products Empol 1043 from BASF and Pripol 1040 from Croda.

The polyester is preferably obtainable at least by reacting at least one aliphatic polymerized, preferably at least one dimerized and / or trimerized, aliphatic C 12-24 monocarboxylic acid and optionally at least one aliphatic C 12-24 monocarboxylic acid with at least one C 2 C 20 polyol and / or C 2 -C2o-diol.

Preferably, the polymerized aliphatic C12-C24 monocarboxylic acid obtainable from the at least one polymerized aliphatic C12-C24 monocarboxylic acid used for the preparation of the polyester used as polymeric resin (P2) are present in the polyester in an amount ranging from 10 to 80 mol%, preferably 10 to 60 mol -%, particularly preferably 10 to 40 mol%, based on the total weight of the polyester, before. It is clear to a person skilled in the art that the polymerized aliphatic C 12-24 monocarboxylic acid used is not completely integrated into the polyester, but rather in the reaction of the at least one polyol and / or diol with the at least one polymerized aliphatic C 12-24 monocarboxylic acid With elimination of water by formation of ester bonds for the construction of structural units present in the polyester comes. The at least one polymerized aliphatic C 12-24 monocarboxylic acid used to prepare the polyester used as polymeric resin (P2) is particularly preferably a dimerized and / or trimerized C 12-24 monocarboxylic acid and the structural unit obtainable therefrom is present in the polyester in an amount in one Range from 12 to 38 mol%, very particularly preferably in a range from 14 to 36 mol% or in a range from 1 6 to 34 mol% or in a range from 18 to 32 mol% % or in a range of 20 to 30 mol% or in a range of 22 to 28 mol%, particularly preferably in a range of 23 to 26 mol%, each based on the total weight of the polyester.

The other starting compounds which can be used for the preparation of polyesters, such as, for example, polyols, such as diols or further dicarboxylic acids or monocarboxylic acids or else lactones and hydroxycarboxylic acids, are known to the person skilled in the art and require no further mention at this point.

The person skilled in the art is suitable polyesters which can be used as polymeric resin (H) and their preparation, for example from DE 40 09 858 A1.

Suitable organic solvents which are present in addition to water in any case in the mixture (vdM), the components known to the expert in this context in question. Examples of such organic solvents are (hetero) cyclic, (hetero) aliphatic or (hetero) aromatic hydrocarbons, monohydric or polyhydric alcohols, ethers, esters, ketones and amides, such as. As N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, toluene, xylene, butanol, ethyl and butyl glycol and their acetates, butyldiglycol, diethylene glycol dimethyl ether, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, isophorone or mixtures thereof.

The emulsifiers already mentioned above, preferably in the mixture (vdM), hereinafter also referred to as emulsifiers (E), may be the components known to the person skilled in the art in this connection. The emulsifiers are preferably selected from the group consisting of lecithins and C 12-24 fatty alcohol polyglycol ethers. The polyglycol ethers used may be completely or partially etherified with C 12-24 fatty alcohols. A suitable lecithin, ie a suitable phospholipid, is for example Lipotin® A, which is commercially available. Also suitable is soy lecithin. Suitable C12-C24 fatty alcohol polyglycol esters are, for example, the commercially available products Lutensol® ON 60 and Lutensol® XP 70. As a consequence, preferred proportions and ratios of the compulsory or preferred components contained in the mixture (vdM) are specified.

If at least one emulsifier (E) is used to prepare the mixture (vdM), the relative weight ratio of the polymeric resins (H) to the component (E) is preferably in the range from 50: 1 to 1.5: 1, particularly preferably Range of 35: 1 to 1, 75: 1, most preferably in the range of 30: 1 to 1, 5: 1, particularly preferably in the range of 10: 1 to 2: 1.

Preferably, the at least one emulsifier (E) in the mixture (vdM) in an amount of 0.1 to 10 wt .-%, particularly preferably from 0.1 to 7.5 wt .-%, most preferably from 1, 5 to 5 wt .-%, each based on the total weight of the mixture (vdM) before.

Preferably, the relative weight ratio of the polymeric resins (H) and the polyamides (P) in the mixture (vdM) to each other is in a range of 20: 1 to 1: 1, more preferably in a range of 17.5 to 1.2: 1, most preferably in a range of 15: 1 to 2: 1.

Preferably, the polyamide (P) in the mixture (vdM) in an amount in a range of 0.1 to 15 wt .-%, particularly preferably from 0.2 to 12.5 wt .-%, most preferably from 0 From 5 to 10% by weight, more preferably from 0.75 to 9% by weight, most preferably from 1 to 8% by weight, or from 1 to 7% by weight, based in each case on the total weight of the mixture, available.

Preferably, the at least one polymeric resin (H) in the blend (vdM) is in an amount ranging from 5.0 to 40 wt%, more preferably from 7.5 to 35.0 wt%, each on the total weight of the mixture, present.

The determination or determination of the proportion of various components such as a polymeric resin or a polyamide on a mixture (vdM) or a basecoat is determined by the determination of the solid (also called non-volatile content, solids content or solids content) of the dispersion, Solution or dissolution of the respective component added to the mixture or basecoat.

The term solids content (non-volatile content) is to be understood as meaning the proportion by weight which remains under evaporation as a residue under defined conditions (measurement method see example part).

The proportion of organic solvents in the mixture (vdM) is for example from 5 to 60 wt .-%, preferably 10 to 55 wt .-%, each based on the total weight of the mixture.

The proportion of water in the mixture (vdM) can vary widely and is for example from 2 to 70 wt .-%, each based on the total weight of the mixture.

Preferably, the above-described components, namely the polyamides (P), the resins (H), the emulsifiers (E) and water and organic solvents at least 90 wt .-%, preferably at least 95 wt .-% of the mixture (vdM) ,

The proportion of the mixture (vdM), based on the total amount of the basecoat (b.2.1), is preferably from 5 to 30 wt .-%, particularly preferably 7.5 to 25 wt .-%.

In this case, the procedure is preferably such that the at least one polyamide (P) in a proportion of 0.05 to 5 wt .-%, particularly preferably in an amount in a range of 0.1 to 4.0 wt .-%, completely particularly preferably in an amount in a range from 0.15 to 3.0% by weight, more preferably in an amount in a range from 0.2 to 2.0% by weight, based in each case on the total weight of the basecoat material ( b.2.1), contained in the basecoat.

In the case of a possible specification on basecoats containing preferred blends (vdM) in a particular range of shares, the following applies. The mixtures (vdM) which do not fall into the preferred group may of course continue to be included in the basecoat. The special share range then applies only to the preferred group of mixtures (vdM). However, it is preferred that for the Total content of mixtures consisting of mixtures (vdM) of the preferred group and mixtures (vdM), which do not fall into the preferred group, also the specific share range applies.

Thus, if a restriction to a range of from 5 to 35% by weight and a preferred group of mixtures (vdM) were to be carried out, this proportion range evidently initially applies only to the preferred group of mixtures (vdM). However, it would then be preferred that a total of all originally included mixtures (vdM), also from 5 to 35 wt .-% are included. Thus, if 25% by weight of mixtures (vdM) of the preferred group are used, then at most 10% by weight of the mixtures (vdM) of the non-preferred group can be used.

In the context of the present invention, the abovementioned principle applies to all the components of the basecoat material mentioned and their ranges of proportions, for example the pigments mentioned below or also the crosslinking agents mentioned below, such as melamine resins.

The basecoat (b.2.1) to be used according to the invention preferably contains at least one pigment. By this are to be understood per se known coloring and / or optically effecting pigments.

Such color pigments and effect pigments are those skilled in the art, for example, in Römpp Lexikon coatings and printing inks, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 176 and 451 described. The terms coloring pigment and color pigment as well as the terms optically effecting pigment and effect pigment are interchangeable.

Preferred effect pigments are, for example, platelet-shaped metallic effect pigments such as platelet-shaped aluminum pigments, gold bronzes, fire-colored bronzes and / or iron oxide aluminum pigments, pearl pigments such as fish-silver, basic lead carbonate, bismuth oxychloride and / or metal oxide mica pigments and / or other effect pigments such as platelet-shaped graphite, platelet-shaped iron oxide, multilayer Effect pigments from PVD films and / or liquid crystal polymer Pigments. Particular preference is given to platelet-shaped metallic effect pigments, in particular platelet-shaped aluminum pigments.

Typical color pigments include, in particular, inorganic color pigments, such as white pigments, such as titanium dioxide, zinc white, zinc sulfide or lithopone; Black pigments such as carbon black, iron manganese black or spinel black; Colored 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 and manganese violet, iron oxide red, cadmium sulfoselenide, molybdate red or ultramarine red; Iron oxide brown, mixed brown, spinel and corundum phases or chrome orange; or iron oxide yellow, nickel titanium yellow, chromium titanium yellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow or bismuth vanadate.

The proportion of the pigments is preferably in the range from 1, 0 to 40.0 wt .-%, preferably 2.0 to 35.0 wt .-%, particularly preferably 5.0 to 30.0 wt .-%, each based on the total weight of the aqueous basecoat (b.2.1).

The aqueous basecoat (b.2.1) contains at least one polymer as a binder, in particular at least one polymer selected from the group consisting of polyurethanes, polyesters, poly (meth) acrylates and / or copolymers of said polymers, especially polyesters, poly (meth) acrylates and / or polyurethane-poly (meth) acrylates. At least one polymer as a binder is always proportionally or completely contained by the addition of the mixture (vdM). Preferably, however, at least one further polymer is used as binder, which is not added in the form of the mixture (vdM). The basecoat material (b.2.1) preferably comprises at least one polymer selected from the group consisting of polyurethanes, polyesters, poly (meth) acrylates and / or copolymers of said polymers, which is not present in the form of the mixture (vdM).

Preferred polyesters are described, for example, in DE 4009858 A1 in column 6, line 53 to column 7, line 61 and column 10, line 24 to column 13, line 3 or WO 2014/033135 A2, page 2, line 24 to page 7, line 10 and page 28, line 13 to page 29, line 13 described. Preferred polyurethane-poly (meth) acrylate copolymers ((meth) acrylated polyurethanes) and their preparation For example, in WO 91/15528 A1, page 3, line 21 to page 20, line 33 and DE 4437535 A1, page 2, line 27 to page 6, line 22 described. The polymers described as binders are preferably hydroxy-functional and more preferably have an OH number in the range from 15 to 200 mg KOH / g, more preferably from 20 to 150 mg KOH / g. Particularly preferably, the basecoats contain at least one hydroxy-functional polyurethane-polyacrylate copolymer, more preferably at least one hydroxy-functional polyurethane-poly (meth) acrylate copolymer and at least one hydroxy-functional polyester.

Also preferably used are poly (meth) acrylates, in particular those which can be prepared by multistage free-radical emulsion polymerization of olefinically unsaturated monomers in water. Particularly preferred are poly (meth) acrylate-based polymeric resins, which by

i. Polymerization of a mixture of olefinically unsaturated monomers A by emulsion polymerization in water using an emulsifier and a water-soluble initiator,

ii. Polymerization of a mixture of olefinically unsaturated monomers B by emulsion polymerization in water using an emulsifier and a water-soluble initiator in the presence of under i. polymer obtained, this mixture of olefinically unsaturated monomers B preferably containing at least one polyunsaturated monomer,

iii. Polymerization of a mixture of olefinically unsaturated monomers C by emulsion polymerization in water using an emulsifier and a water-soluble initiator in the presence of the under ii. obtained polymerizate,

can be produced.

The proportion of polymers as binders which are not added in the form of the mixture (vdM) to the basecoat can vary widely and is preferably in the range from 1.0 to 25.0% by weight, preferably 3.0 to 20.0 Wt .-%, particularly preferably 5.0 to 15.0 wt .-%, each based on the total weight of the basecoat (b.2.1). In addition, the basecoat (b.2.1) may contain at least one typical crosslinking agent known per se. If it contains a crosslinking agent, it is preferably at least one aminoplast resin and / or at least one blocked polyisocyanate, preferably an aminoplast resin. Among the aminoplast resins, melamine resins are particularly preferred.

If the basecoat (b.2.1) contains crosslinking agents, the proportion of these crosslinking agents, in particular aminoplast resins and / or blocked polyisocyanates, more preferably amino resins, including preferably melamine resins, preferably in the range of 0.5 to 20.0 wt .-%, preferably 1, 0 to 15.0 wt .-%, particularly preferably 1, 5 to 10.0 wt .-%, each based on the total weight of the basecoat (b.2.1).

In addition, the basecoat (b.2.1) may contain at least one other additive (additive). Examples of such additives are residue-free or substantially residue-free, thermally decomposable salts, of the polymers mentioned above, different physical, thermal and / or actinic radiation curable polymers as binders, other crosslinking agents, organic solvents, reactive diluents, transparent pigments, fillers, molecularly soluble dyes , Nanoparticles, light stabilizers, antioxidants, deaerators, emulsifiers, slip additives, polymerization inhibitors, radical polymerization initiators, adhesion promoters, flow control agents, film-forming aids, sag-control agents (SCAs), flame retardants, corrosion inhibitors, waxes, siccatives, biocides and matting agents. Such additives are used in the usual and known amounts.

The solids content of the basecoat (b.2.1) may vary according to the requirements of the case. In the first place, the solids content depends on the viscosity required for application, in particular spray application. It is of particular advantage that the basecoat material to be used according to the invention can nevertheless have a viscosity at comparatively high solids, which permits adequate application. Preferably, the solids content of the basecoat is at least 1 6.5%, preferably at least 18.0%, more preferably at least 20.0%.

In the conditions mentioned, that is to say at the stated solids contents, preferred basecoats (b.2.1) have a viscosity of 40 to 150 mPa · s, in particular 70 to 120 mPa · s, at 23 ° C. and a shear stress of 1000 l / s (For more details on the measuring method, see the example section). In the context of the present invention, a viscosity in this range at the specified shear stress is referred to as the spray viscosity (processing viscosity). As is known, coating compositions are applied at spray viscosity, that is to say they have a viscosity under the conditions then present (high shear stress) which, in particular, is not too high in order to allow effective application. This means that the adjustment of the spray viscosity is important in order to be able to apply a paint at all by spraying methods and to ensure that a complete, uniform coating film can be formed on the substrate to be coated.

The basecoat (b.2.1) to be used according to the invention is aqueous, ie it is a system which contains as solvent mainly water and organic solvents only in minor proportions.

The proportion of water in the basecoat (b.2.1) is preferably from 35 to 75 wt .-%, more preferably 45 to 70 wt .-%, each based on the total weight of the basecoat.

It is again preferred that the percentage sum of the solids of the basecoat and the proportion of water in the basecoat is at least 70% by weight, preferably at least 75% by weight. Preferred among these are ranges of from 75 to 95% by weight, in particular from 80 to 90% by weight.

This means, in particular, that preferred basecoats contain principally polluting components, in particular organic solvents, in relation to the solids of the basecoat, at only small proportions. Preferably, the ratio of the volatile organic content of the basecoat material (in% by weight) and the solids content of the basecoat material (analogous to the above representation here in wt. %) from 0.1 to 1.5, more preferably from 0.2 to 1.0. In the context of the present invention, the volatile organic content is the proportion of the basecoat which is calculated neither in relation to the proportion of water nor to the solids.

A further advantage of the basecoat (b.2.1) is that it can be prepared without the use of organic solvents harmful to health and the environment such as N-methyl-2-pyrrolidone, dimethylformamide, dioxane, tetrahydrofuran and N-ethyl-2-pyrrolidone , Accordingly, the basecoat preferably contains less than 10% by weight, preferably less than 5% by weight, more preferably less than 2.5% by weight of organic solvents selected from the group consisting of N-methyl-2-pyrrolidone, Dimethylformamide, dioxane, tetrahydrofuran and N-ethyl-2-pyrrolidone. Preferably, the basecoat is completely free of these organic solvents.

The preparation of the basecoats can be carried out using the customary and known for the production of basecoats mixing methods and mixing units.

For the basecoats (b.2.2.x) used in the process according to the invention, at least one of these basecoats has the features essential to the invention described for the basecoat (b.2.1). This means in particular that at least one of the basecoats (b.2.2.x) contains at least one mixture (vdM). The preferred features and embodiments described in the description of the basecoat (b.2.1) also preferably apply to at least one of the basecoats (b.2.2.x). Preferably, the above applies to all basecoats used (b.2.2.x).

In the preferred variants of stage (2.2) of the process according to the invention described above, a first basecoat material (b.2.2.a) is first applied, which may also be referred to as a color-preparing basecoat material. It thus serves as a basis for at least one subsequent color and / or effect basecoat layer, that is, a layer which can then optimally fulfill their function of dyeing and / or effecting.

In a particular embodiment, a color-preparing basecoat is substantially free of colored pigments and effect pigments. Especially preferred contains such a basecoat less than 2 wt .-%, preferably less than 1 wt .-% of colored pigments and effect pigments, each based on the total weight of the aqueous basecoat. The color-preparing basecoat preferably contains black and / or white pigments in this embodiment, particularly preferably both types of these pigments. It preferably contains 5 to 30 wt .-%, preferably 10 to 25 wt .-% of white pigments and 0.01 to 1, 00 wt .-%, preferably 0.1 to 0.5 wt .-% black pigments, each based on the total weight of the basecoat. The resulting white, black and especially gray color, which can be adjusted by the ratio of white and black pigments in different brightness levels, represents an individually adaptable basis for the then following basecoat layer construction, so that the color and / or the effect of the following basecoat construction can be optimally used. The pigments are known to the person skilled in the art and also described above. Titanium dioxide is preferred as white pigment, carbon black being preferred as black pigment. As already described, however, this basecoat may of course also contain colored and / or effect pigments. This variant is particularly suitable if the resulting multicoat system is to have a high chromatic hue, for example a very deep red or yellow. If pigments in a correspondingly colored color are also added to the color-preparing basecoat, a further improved coloring can be achieved.

The color and / or effect basecoat (s) for the second or the second and third basecoat layers within this embodiment are adjusted according to the ultimately desired color scheme of the overall structure. If a white, black or gray color is desired, the at least one further basecoat material contains the corresponding pigments and, with regard to the pigment composition, ultimately resembles the paint-priming basecoat material. If a colorful and / or effect coating is desired, for example a varnished varnish or a metallic effect varnish, corresponding colored and / or effect pigments are used in amounts of, for example, from 1 to 15% by weight, preferably from 3 to 10% by weight. , in each case based on the total weight of the basecoat used. Colored pigments belong to the group of color pigments, the latter also including achromatic color pigments, such as black or white pigments. Such basecoats can Of course, for brightness adjustment additionally still black and / or white pigments included.

The inventive method allows the production of multi-layer coatings on metallic substrates waiving a separate curing step. Nevertheless, the use of the method according to the invention results in multicoat paint systems which have optical or aesthetic properties, so that even higher layer thicknesses of the corresponding basecoat films can be built up without any aesthetic loss of quality.

Examples

Solid content (solids, non-volatile content)

The non-volatile content is determined in accordance with DIN EN ISO 3251 (date: June 2008). In this case, 1 g of sample are weighed into a previously dried aluminum dish and dried for 60 minutes at 125 ° C in a drying oven, cooled in a desiccator, and then weighed back. The residue based on the total amount of the sample used corresponds to the nonvolatile fraction. If necessary, the volume of the nonvolatile fraction can be determined according to DIN 53219 (date: August 2009).

layer thicknesses

The layer thicknesses are determined according to DIN EN ISO 2808 (date: May 2007), method 12A using the measuring instrument MiniTest® 3100 - 4100 from ElektroPhysik.

acid number

The acid value is determined in accordance with DIN EN ISO 21 14 (date: June 2002), the procedure being in accordance with "Procedure A." The acid number corresponds to the mass of potassium hydroxide in mg, which is used to neutralize 1 g of sample under the in The acid number of a carboxy-functional component in an otherwise carboxyl group-free sample, for example a polyamide in a as Commercially available solution of the polyamide, can be obtained by appropriate conversion (consideration of the solid, that is the actual active substance of the sample or the amount of polyamide in the solution). It is also possible to isolate the component, for example the polyamide, beforehand and then to determine the acid number of the polyamide itself, that is to say ultimately the solid of the solution obtainable, for example, as a commercial product.

The above indication that basically (that is to say, as a rule) the process was carried out according to "Procedure A" of the specified standard is to be understood as follows: In the event that a sample or a previously isolated component does not completely conform to the method described in US Pat An alternative solvent mixture was used to dissolve the sample or component completely, and optionally also at slightly elevated temperatures, for example 30 ° C., to ensure complete dissolution prior to titration Dissolve various polyamide commercial products, for example Disparlon AQ600, in xyloLPropanol 2: 1 v / v.

Although it is basically possible, of course, to determine the acid number with the solvent mixture specified in the standard, in which case not all of the carboxy functions present are detected, but nevertheless a reproducible and representative result is obtained, in the context of the present invention always a completely dissolved Measure sample or component.

OH number

The OH number is determined in accordance with DIN 53240-2 (date: November 2007). The OH groups are reacted by acetylation with an excess of acetic anhydride. Subsequently, the excess acetic anhydride is split by addition of water to acetic acid and titrated back all the acetic acid with ethanolic KOH. The OH number indicates the amount of KOH in mg which is equivalent to the amount of acetic acid bound in the acetylation of 1 g of sample. Determination of the number average and the weight average molecular weight

The determination of the number average molecular weight (M _n ) is carried out by means of gel permeation chromatography (GPC). The determination method is based on DIN 55672-1 (date: August 2007). In addition to the number average molecular weight, this method can also be used to determine the weight-average molecular weight (M _w ) and the polydispersity (ratio of weight-average molecular weight (M _w ) to number-average molecular weight (M _n )). The eluent used is tetrahydrofuran. The determination is made against polystyrene standards. The column material consists of styrene-divinylbenzene copolymers.

Determination of storage stability

To determine the storage stability of the basecoats these are before and after storage at 40 ° C for 2 weeks with a DIN 53019-1 (Date: September 2008) and according to DIN 53019-2 (Date: February 2001) calibrated rotary viscometer under tempered Conditions (23.0 ° C ± 0.2 ° C) examined. The samples are 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 (discharge phase) .The mean viscosity level during the stress ^phase (high shear viscosity) and the level after 8 minutes unloading phase (Low shear viscosity) are determined from the measured data and the values are compared before and after storage by calculating the respective percentage changes.

Painting of water-based paint wedge assemblies

To assess the occurrence of pinholes and the layer thickness-dependent course wedge-shaped multi-layer coatings are prepared according to the following general rules:

Variant A: First water-based paint as a wedge, second water-based paint as a constant coat

A 30 x 50 cm steel sheet coated with a hardened standard KTL (CathoGuard® 800 from BASF Coatings) is carried along on one longitudinal edge two adhesive strips (Tesaband, 19 mm) provided in order to determine layer thickness differences after coating.

The first aqueous basecoat is electrostatically applied as a wedge with a target layer thickness (layer thickness of the dried material) of 0-30 μηι. This is followed by venting for 3 minutes at room temperature, before the second aqueous basecoat is also applied electrostatically in a single application after removal of one of the two adhesive strips. The target layer thickness (layer thickness of the dried material) is 13-1 6 μηι. After renewed flash-off time of 4 minutes at room temperature, the assembly is oven-dried in a circulating air oven at 60 ° C for 10 minutes.

After removal of the second adhesive strip, a commercially available two-component clearcoat material (ProGloss® from BASF Coatings GmbH) having a target layer thickness (layer thickness of the dried material) of 40-45 μm is applied manually to the intermediate dried structure by means of a flow cup gun. The resulting clearcoat is flashed for 10 minutes at room temperature (18 to 23 ° C); then curing in a convection oven at 140 ° C for another 20 minutes.

Variant B: First water-based paint as a constant coat, second water-based paint as a wedge

A 30 x 50 cm steel sheet coated with a hardened standard cathodic electrocoat (CathoGuard® 800 from BASF Coatings) is provided on one longitudinal edge with two adhesive strips (Tesaband, 19 mm) in order to be able to determine layer thickness differences after the coating.

The first aqueous basecoat is applied electrostatically with a target layer thickness (layer thickness of the dried material) of 18-22 μm. This is followed by venting for 3 minutes at room temperature, before the second aqueous basecoat is also applied electrostatically in a single application as a wedge after removing one of the two adhesive strips. The target layer thickness (layer thickness of the dried material) is 0-30 μηι. After renewed flash-off time of 4 minutes at room temperature, the assembly is oven-dried in a circulating air oven at 60 ° C for 10 minutes.

After removal of the second adhesive strip, a commercially available two-component material is manually applied to the temporarily dried structure by means of a flow cup gun. Clearcoat (ProGloss® BASF Coatings GmbH) with a target layer thickness (layer thickness of the dried material) of 40-45 μηι applied. The resulting clearcoat is flashed for 10 minutes at room temperature (18 to 23 ° C); then curing in a convection oven at 140 ° C for another 20 minutes.

Assessment of the occurrence of pinholes

To assess the occurrence of pinholes, multicoat paint systems are prepared in accordance with the methods for painting water-based paint wedge assemblies (Variant A or B, respectively) and then evaluated visually according to the following general specification:

The dry layer thickness of the entire water-based paint system, consisting of the first and the second aqueous basecoat, is controlled and for the basecoat layer thickness wedge the areas of 0-20 μηι and 20 μηι are marked to the end of the wedge on the steel sheet.

The evaluation of the pinholes is done visually in the two separate areas of the waterborne paint wedge. For each area, the number of pinholes is counted. All results are normalized to an area of 200 cm ² . In addition, if necessary, it is recorded from which dry layer thickness of the waterborne base wedge no more needle sticks occur.

Assessment of the layer-thickness-dependent course

To assess the layer thickness-dependent course, multicoat paint systems are prepared according to the methods for painting water-based paint wedge assemblies (variants A or B) and then evaluated according to the following general specification:

The dry film thickness of the entire aqueous basecoat composition, consisting of the one or the first and the second waterborne basecoat, is controlled and for the basecoat film thickness wedge become the ranges of 15-20 μηι and 20- 25 μηι or 10-15 μηπ, 15 -20 μηπ, 20-25 μηπ, 25-30 μηι and optionally 30- 35 μηι marked on the steel sheet. The determination or evaluation of the layer thickness-dependent course is carried out with the help of the measuring device Wave scan by Byk / Gardner within the four previously determined basecoat layer thickness ranges. For this purpose, a laser beam is directed at an angle of 60 ° to the surface to be examined, and there are the fluctuations of the reflected light in a so-called short wave range (0.3 to 1, 2 mm) and in the so-called long wave range (1, 2 to 12 mm) with the aid of the measuring device (long wave = LW, short wave = SW, the lower the values, the better the appearance). In addition, as a measure of the sharpness of an image reflected in the surface of the multi-layer structure, the characteristic "distinctness of imgage" (DOI) is determined with the aid of the measuring device (the higher the value, the better the appearance).

Assessment of the appearance of specks

To assess the appearance of specks, the basecoats are tested according to the following general rules: a) Coating a glass sheet

The corresponding water-based paint is applied by means of a 150 μηι box doctor on a glass plate of dimensions 9 x 15 cm. When wet, as well as after a 60 minute flash off at room temperature, the film is visually assessed for specks by being held against a light source so as not to misinterpret any air pockets as specks. It is given a grade of 1 -5 (1 = no specks / 5 = very many specks) or it is judged in relation to a reference (reference = 0; ++ = much better; + = better; - = worse; = much worse). b) coating a steel sheet

The waterborne basecoat is applied by means of two-coat application on a steel panel measuring 32 × 60 cm coated with a hardened standard cathodic electrocoat (CathoGuard® 800 from BASF Coatings); the application in the first step is carried out electrostatically with a target layer thickness of 8-9 μηπ, in the second step is pneumatically applied after a 2-minute flash off at room temperature with a target layer thickness of 4-5 μηι. The resulting aqueous basecoat film is then dried after renewed flash off at room temperature for 5 minutes in a convection oven for 5 minutes at 80 ° C. On the dried Waterborne basecoat is a commercially available two-component clearcoat (ProGloss BASF Coatings GmbH) with a target layer thickness of 40-45 μηι applied. The resulting clearcoat is flashed off for 10 minutes at room temperature; then curing in a convection oven at 140 ° C for another 20 minutes. The evaluation of specks is done visually; a grade of 1 -5 is awarded (1 = no specks / 5 = very many specks).

Visual assessment for segregation

The basecoats are visually evaluated for stability by storing each in a sealed glass jar at room temperature and / or at 40 ° C for a period of at least four weeks. It is then checked visually whether a separation has taken place or whether the material has changed in terms of its homogeneity. It is given a grade of 1 -5 (1 = very stable, no segregation or no formation of multiple phases / 5 = very unstable, strong demixing or very distinct formation of several phases).

1 . Preparation of mixtures containing polyamides and preparation of aqueous basecoats

The following should be considered with regard to the formulation constituents and their amounts given in the tables below. If reference is made to a commercial product or a manufacturing specification described elsewhere, exactly this commercial product or exactly the product produced within the scope of the referenced specification is meant, irrespective of the particular main designation of the constituent selected in each case.

If a formulation constituent therefore has the main designation "melamine-formaldehyde resin" and if a commercial product is indicated, then the melamine-formaldehyde resin is used as precisely this commercial product shall be. Thus, if reference is made to a preparation rule for a formulation component and, for example, a polymer dispersion having a certain solids results in this preparation, then precisely this dispersion is used. It is not decisive whether the term "polymer dispersion" or merely the active substance, for example "polymer", "polyester" or "polyurethane-modified polyacrylate" was chosen as the main name. This must be taken into account if the amount of the active substance (the polymer) is to be deduced. All parts given in the tables are parts by weight.

1 .1 Preparation of predispersed mixtures (vdM) and other mixtures containing polyamides

The components listed in Tables 1 .1 and 1 .2 are stirred together in the stated sequence with stirring at a temperature of 15-25 ° C. to give mixtures (vdM) 1 to 6 to be used according to the invention. Subsequently, this mixture is homogenized for a further 10 minutes with stirring. Stirring was carried out using the device "Dispermat® LC30" from VWA-Getzmann, Germany, at a circumferential speed of the stirring disk used of 15 to 20 m / s.

Table 1.1: Preparation of mixtures (vdM) 1 to 4

(vdM) 1 (VdM) 2 (vdM) 3 (vdM) 4

Melamine formaldehyde resin (Cymel® 303 of

23.9 26.7

Company Allnex)

Melamine formaldehyde resin (esimene® 755 of

26.7

Company Ineos)

Melamine-formaldehyde resin (Resimene® HM 2608

23.5 of the company Ineos)

Dimethylethanolamine 0.8 0.5 0.5 0.4

Disparlon® A670-20M, available from Kusomoto

13.7 16.2 16.2 14.3

Chemicals, Ltd.

Butyl glycol 32.9 32.5 32.5 28.7 2,4,7,9-tetramethyl-5-decynediol, 52% in BG

3.6 4.9 4.9 4.3

(available from BASF SE)

Polyester; prepared according to Example D, column

25.1 19.2 19.2 28.7

16, Z. 37-59 DE 40 09 858 AI

Table 1.2: Preparation of the mixtures (vdM) 5 and (vdM) 6

Polyester; prepared according to Example D, column 16,

22,50 22,50

Z. 37-59 DE 40 09 858 AI

Dimethylethanolamine 0.45 0.45

2,4,7,9-tetramethyl-5-decynediol, 52% in BG

3.00 3.00

(available from BASF SE)

LIPOTIN® A, available from Evonik Industries AG 3.00 3.00

deionized water 56.05 56.05

Disparlon® ^® 6900-20X available from Kusomoto

15.00

Chemicals, Ltd.

Disparlon® ^® A670-20M available from Kusomoto

15.00

Chemicals, Ltd.

The components listed in Tables 1 .3 are stirred together in the stated sequence while stirring to form polyamide-containing mixtures PM 1 and 2 to be used for comparison. Subsequently, this mixture is stirred vigorously for 10 minutes.

Table 1.3: Preparation of polyamide-containing mixtures PM 1 and 2

PM 1 PM 2

Disparlon® AQ630, available from Kusomoto

Chemicals, Ltd.

Disparlon® AQ600, available from Kusomoto ^

Chemicals, Ltd.

Isobutanol 18.5

deionized water 78.5 31.5

2,4,7,9-tetramethyl-5-decynediol, 52% in BG

(available from BASF SE)

Agitan® 282 from Münzing Chemie GmbH 0.5 The polyamide in the commercial product Disparlon® AQ600 from Kusumoto Chemicals, Ltd. (non-volatile content of the commercial product: 20% by weight) has an acid value of 66 mg KOH / g.

The polyamide in the commercial product Disparlon® AQ630 from Kusumoto Chemicals, Ltd. (non-volatile content of the commercial product: 18% by weight) has an acid number of 75 mg KOH / g.

The polyamide in the commercial product Disparlon® A670-20M from Kusumoto Chemicals, Ltd. (Non-volatile content of the commercial product: 20% by weight) has an acid value of 9 mg KOH / g.

The polyamide in the commercial product Disparlon® 6900-20X from Kusumoto Chemicals, Ltd. (Non-volatile content of the commercial product: 20% by weight) has an acid value of 9 mg KOH / g.

1 .2 Preparation of aqueous basecoats

1 .2A Preparation of aqueous basecoats WBL A1 (comparison) and WBL A2 (comparison)

The components listed in Table A under "aqueous phase" are stirred together in the order indicated to an aqueous mixture, then stirred for 10 minutes and adjusted to a pH of 8 and a spray viscosity of 90 mPa.s using deionized water and dimethanolamine. s at a shear stress of 1291 s ^~ measured with a rotary viscometer (Rheolab QC device with tempering system C-LTD80 / QC Anton Paar) at 23 ° C, set.

Table A: Preparation of waterborne basecoats WBL A1 and WBL A2 WBL A1 WBL A2

Aqueous phase:

3% Na-Mg layered silicate solution 15.23 15.23

deionized water 5.68

1-propoxy-2-propanol 1.41 1.41

2-ethylhexanol 0.87 0.87

Graft copolymer based on polyurethane;

prepared according to page 35, line 33 to page 36, line 22 26,51

(Example D-B2) of WO 2015/007427 Al

Aqueous dispersion of a poly (meth) acrylate emulsion polymer having a non-volatile content 31,23

from 26-28%

Polyester; prepared according to page 28, lines 13 to 33

3.66

(Example BEI) WO 2014/033135 A2

Polyester; prepared according to Example D, column 16, Z. 37-

4.85

59 of DE 40 09 858 AI

Melamine formaldehyde resin (Cymel® 203 of the company

5.44 5.44

Allnex)

10% dimethylethanolamine in water 0.55 0.30

2,4,7,9-tetramethyl-5-decynediol, 52% in BG (available

from BASF SE) 1.09 1.09

Triisobutyl phosphate 1.63 1.63

Polyurethane-modified polyacrylate; manufactured according to

2.91 2.91

P. 7, Z. 55 to p. 8, Z. 23 of DE 4437535 AI

Butyl glycol 4.35 4.35

Isopar® L, available from Exxon Mobile 1.84 1.84

Pluriol® P900, available from BASF SE 0.54 0.54

Hydrosol A170, available from DHC Solvent Chemie

GmbH 0.54 0.54

White paste 25,68 25,68

Black paste 1.53 1.52

Yellow paste 0.54 0.54

Production of white paste

The white paste is made from 50 parts by weight of titanium rutile 2310, 6 parts by weight of a polyester prepared according to Example D, column 1 6, Z. 37-59 of DE 40 09 858 A1, 24.7 parts by weight of a patent application EP 022 8003 B2, S. 8, Z. 6 to 18 prepared binder dispersion, 10.5 parts by weight of deionized water, 4 parts by weight of 2,4,7,9-tetramethyl-5-decynediol, 52% in BG (available from BASF SE), 4.1 parts by weight of butylglycol , 0.4 parts by weight of 10% dimethylethanolamine in water and 0.3 parts by weight of Acrysol RM-8 (available from The Dow Chemical Company). Production of black paste

The black paste is composed of 57 parts by weight of a polyurethane dispersion prepared according to WO 92/15405, page 13, line 13 to page 15, line 13, 10 parts by weight of carbon black (carbon black Monarch® 1400 from Cabot Corporation), 5 parts by weight of a polyester, prepared according to Example D, column 1 6, Z. 37-59 of DE 40 09 858 A1, 6.5 parts by weight of a 10% aqueous dimethylethanolamine solution, 2.5 parts by weight of a commercially available polyether (Pluriol® P900, available from BASF SE ), 7 parts by weight of butyldiglycol and 12 parts by weight of deionized water.

Preparation of the yellow paste

The yellow paste is made from 37 parts by weight of Bayferrox 3910 (available from Lanxess), 49.5 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, lines 26 to 25, Z. 24, 7.5 parts by weight Disperbyk®-184 (available from BYK-Chemie GmbH) and 6 parts by weight of deionized water.

1 .2B Preparation of aqueous basecoats WBL B1 (comparison), WBL B2 (according to the invention) and WBL 3-6 (comparison)

The components listed in Table B under "aqueous phase" are stirred together in the order listed to form an aqueous mixture, which is then stirred for 10 minutes and brought to a pH of 8 and a spray viscosity of 10 ± 10 using deionized water and dimethanolamine 10 mPa-s at a shear stress of 1000 s ^_1 , measured with a rotary viscometer (Rheolab QC device with tempering system C-LTD80 / QC Anton Paar) at 23 ° C, adjusted.

Table B: Preparation of waterborne basecoats WBL B1 to WBL B6

WBL Bl WBL B2 WBL B3 WBL B4 WBL B5 WBL B6

Aqueous phase: 3% NaMg layered silicate solution 13.54

(vdM) 1 17.52

PM 1 12.06 18.09

PM 2 3.95 5.60 Deionized water 8.03 18.81

2-ethylhexanol 1.54 1.54 1.54 1.54 1.54 1.54

Aqueous dispersion of a

Poly (meth) acrylate

An emulsion polymer having a 44.04 44.04 44.04 44.04 44.04 44.04 non-volatile content of

26-28%

Polyester; manufactured according to

Example D, column 16, lines 37-59 of the 4.40 4.40 4.40 4.40 4.40

DE 40 09 858 AI)

Melamine formaldehyde resin

3.96 3.96 3.96 3.96 3.96 (Cymel® 303 from Allnex)

10% dimethylethanolamine in

1.21 1.21 1.21 1.21 1.21 water

2,4,7,9-tetramethyl-5-decyne diol,

52% in BG (available from BASF 0.63 0.63 0.63 0.63 0.63 0.63

SE)

Pluriol® P900, available from BASF

1.26 1.26 1.26 1.26 1.26 1.26 SE

Triisobutyl phosphate 0.55 0.55 0.55 0.55 0.55 0.55

NACU E 2500, available from King

0.72 0.72 0.72 0.72 0.72 0.72

Industries, Inc

Butyl glycol 5,18 5,18 5,18 5,18 5,18

50% by weight solution of

Rheovis® PU1250 in butylglycol

0.63 0.63 0.63 0.63 0.63 0.63

(Rheovis® PU1250 available from

BASF SE)

Black paste 14.31 14.31 14.31 14.31 14.31 14.31

Percentage of polyamide in basecoat: 0.00% 0.48% 0.48% 0.48 0.67% 0.67%

Making black paste

The black paste is composed of 57 parts by weight of a polyurethane dispersion prepared according to WO 92/15405, page 13, line 13 to page 15, line 13, 10 parts by weight of carbon black (carbon black Monarch® 1400 from Cabot Corporation), 5 parts by weight of a polyester, prepared according to Example D, column 1 6, Z. 37-59 of DE 40 09 858 A1, 6.5 parts by weight of a 10% aqueous dimethylethanolamine solution, 2.5 parts by weight of a commercially available polyether (Pluriol® P900, available from BASF SE ), 7 parts by weight of butyldiglycol and 12 parts by weight of deionized water. 1 .2C Preparation of aqueous basecoats WBL B7 and B9 (comparison) and WBL B8 and WBL 10 (according to the invention)

The components listed in Table C under "aqueous phase" are stirred together in the order given to an aqueous mixture, then stirred for 10 minutes and with the aid of deionized water and dimethanolamine to a pH of 8 and an injection viscosity of 60 ± 5 mPa-s (WBL B7, WBL B9) or 80 ± 5 mPa-s (WBL B8, WBL B10) at a shear load of 1000 s ^"1 , measured with a rotary viscometer (Rheolab QC with temperature control system C-LTD80 / QC Anton Paar) at 23 ° C, set.

Table C: Preparation of waterborne basecoats WBL B7 to WBL B10

WBL B7 WBL B8 WBL B9 WBL BIO

Aqueous phase:

3% Na-Mg phyllosilicate solution 12.29 12.29

(vdM) 2 14,45

(vdM) 3 14,44 deionized water 8,74 13,50 8,73 13,50 n-Propanol 0,82 0,82 0,82 0,82 n-Butoxipropanol 1,29 1,29 1,29 1, 29 2-Ethylhexanol 2.60 2.60 2.60 2.60 Aqueous dispersion of a

Poly (meth) acrylate emulsion polymer

42.73 42.73 42.74 42.74 with a non-volatile portion of

26-28%

Polyester; prepared according to Example D,

2,77 2,77

Column 16, Z. 37-59 of DE 40 09 858 AI

Melamine formaldehyde resin (Cymel® 303

3.86

the company Allnex)

Melamine formaldehyde resin (esimene®

3.86

755 of the company Ineos) 10% dimethylethanolamine in water 0.28 0.28

2,4,7,9-tetramethyl-5-decynediol, 52% in

1.30 1.30 1.30 1.30 BG (available from BASF SE)

BYK-346, available from Altana / BYK

0.43 0.43 0.43 0.43

Chemistry GmbH

Isopropanol 1.54 1.54 1.54 1.54

Butyl glycol 0.94 0.94 0.94 0.94

Isopar® L available from Exxon Mobile 0.82 0.82 0.82 0.82

NACU E 2500, available from King

0.40 0.40 0.40 0.39

Industries, Inc

Black paste 13.13 13.13 13.13 13.13

Barium sulphate paste 3.00 3.00 3.00 3.00

Steatite paste 3.05 3.05 3.05 3.05

Making black paste

Preparation of barium sulfate paste

The barium sulfate paste is composed of 39 parts by weight of a polyurethane dispersion prepared according to EP 0228003 B2, page 8, lines 6 to 18, 54 parts by weight of barium sulfate (blanc fixe micro from Sachtleben Chemie GmbH), 3.7 parts by weight of butyl glycol and 0.3 part by weight Agitan 282 (available from Münzing Chemie GmbH) and 3 parts by weight of deionized water.

Making steatite paste

The steatite paste is from 49.7 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, Z. 26 to p. 25, Z. 24, 28.9 parts by weight of steatite (Microtalc IT extra from Mondo Minerals BV), 0.4 parts by weight of Agitan 282 (available from Münzing Chemie GmbH), 1.45 parts by weight of Disperbyk®-184 (available from BYK-Chemie GmbH), 3.1 parts by weight of a commercial grade Polyethers (Pluriol® P900, available from BASF SE) and 1 6.45 parts by weight of deionized water.

1 .2D Preparation of aqueous basecoats WBL B11 (comparison) and WBL B12 (according to the invention)

The components listed under "aqueous phase" in Table D are stirred together in the order listed to form an aqueous mixture, which is then stirred for 10 minutes and brought to a pH of 8 and a spray viscosity of 90 ± 5 using deionized water and dimethanolamine mPa-s at a shear stress of 1000 s ^_1 , measured with a rotary viscometer (device Rheolab QC with tempering C-LTD80 / QC Anton Paar) at 23 ° C, adjusted.

Table D: Preparation of waterborne basecoats WBL B11 and WBL B12

WBL Bll WBL B12

Aqueous phase:

3% NaMg layered silicate solution 4.20

(vdM) 5 8,20

deionized water 6.36 4.57

Butyl glycol 4.00 4.00

2-ethylhexanol 3,55 3,55

Aqueous dispersion of a poly (meth) acrylate emulsion polymer having a non-volatile content of 13.96 13.96

from 26-28%

Polyester; prepared according to Example D, column 16, Z. 37-59

4.85 3.01

DE 40 09 858 AI

deionized water 4,20

30% by weight aqueous heovis® AS 1130 solution,

0.42

available from BASF SE

Melamine-formaldehyde resin (Cymel® 203 from Allnex) 7,70 7,70

2,4,7,9-tetramethyl-5-decynediol, 52% in BG (available

1.80 1.65

from BASF SE) 10% dimethylethanolamine in water 1.08 0.88

Pluriol® P900, available from BASF SE 0.10 0.10

Triisobutyl phosphate 2.50 2.50

White paste 51,90 51,90

Yellow paste 0.12 0.12

Black paste 0.11 0.11

Steatite paste 2,40 2,40

Making white paste

The white paste is composed of 34 parts by weight of titanium rutile 2310, 43.3 parts by weight of an aqueous dispersion of a poly (meth) acrylate emulsion polymer having a nonvolatile content of 26-28%, 3.9 weight percent butyl glycol, 1.6.7 weight parts of deionized water and 2 , 1 part by weight of Disperbyk®-184 (available from BYK-Chemie GmbH).

Making yellow paste

The yellow paste is composed of 47 parts by weight of Sicotan Yellow L 1912, 45 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, line 26 to page 25, line 24, 2.7% by weight of 1-propoxy-2 propanol, 2.8 parts by weight of deionized water, 1.5 parts by weight of Disperbyk®-184 (available from BYK-Chemie GmbH) and 1 part by weight of Aerosil R 972 (available from Evonik Industries).

Making black paste

The black paste is made from 40 parts by weight of Bayferrox 318 M (available from Lanxess), 39 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, line 26 to page 25, line 24, 2.0% by weight 1 -Propoxy-2-propanol, 1 1, 1 parts by weight of deionized water, 0.5 parts by weight of Agitan 282 (available from Münzing Chemie GmbH), 4.4 parts by weight of Pluriol® P900 (available from BASF SE) and 3 parts by weight of 10% dimethylethanolamine in Water produced.

Making steatite paste

The steatite paste is from 49.7 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, Z. 26 to p. 25, Z. 24, 28.9 parts by weight of steatite (Microtalc IT extra from Mondo Minerals BV), 0.4 parts by weight of Agitan 282 (available from Münzing Chemie GmbH), 1.45 parts by weight of Disperbyk®-184 (available from BYK-Chemie GmbH), 3.1 parts by weight of a commercial polyether (Pluriol® P900, available from BASF SE) and 1.65 parts by weight of deionized Water produced.

1 .2E Preparation of aqueous basecoats WBL B13 (comparison) and WBL B14 (according to the invention)

The components listed under "aqueous phase" in Table E are stirred together in the order listed to form an aqueous mixture, which is then stirred for 10 minutes and brought to a pH of 8 and an injection viscosity of 85 ± 5 using deionized water and dimethanolamine mPa-s at a shear stress of 1000 s ^_1 , measured with a rotary viscometer (device Rheolab QC with tempering C-LTD80 / QC Anton Paar) at 23 ° C, adjusted.

Table E: Preparation of waterborne basecoats WBL B13 and WBL B14

3% Na-Mg layered silicate solution

(vdM) 5

1-propoxy-2-propanol

2-ethylhexanol

Aqueous dispersion of a poly (meth) acrylate emulsion polymer having a non-volatile content

from 26-28%

Polyester; prepared according to Example D, column 16, Z. 37-59

DE 40 09 858 AI

Melamine-formaldehyde resin (esimene® HM 2608 of the company

5.44 5.44

Ineos)

10% dimethylethanolamine in water 0.60 0.30

2,4,7,9-tetramethyl-5-decynediol, 52% in BG (available

1.09 1.09

from BASF SE)

Butyl glycol 4.35 4.35

Isopar® L, available from Exxon Mobile 1.84 1.84

Hydrosol A170, available from DHC Solvent Chemie GmbH 0.54 0.54 Pluriol® P900, available from BASF SE 0.54 0.54

Triisobutyl phosphate 1.63 1.63

Tinuvin ^® 384-2, available from BASF SE 0.80 0.80

Tinuvin ^® 123, available from BASF SE 0.40 0.40

White paste 54.31 54.31

Yellow paste 0.12 0.12

Black paste 0.11 0.11

Steatite paste 2.23 2.23

Making white paste

The white paste is composed of 34 parts by weight of titanium rutile 2310, 43.3 parts by weight of an aqueous dispersion of a poly (meth) acrylate emulsion polymer having a nonvolatile content of 26-28, 3.9% by weight of butyl glycol, 1.6.7 parts by weight of deionized water and 2, 1 part by weight of Disperbyk®-184 (available from BYK-Chemie GmbH).

Making yellow paste

Making black paste

Making steatite paste The steatite paste is from 49.7 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, Z. 26 to p. 25, Z. 24, 28.9 parts by weight of steatite (Microtalc IT extra from Mondo Minerals BV), 0.4 parts by weight Agitan 282 (available from Münzing Chemie GmbH), 1.45 parts by weight Disperbyk®-184 (available from BYK-Chemie GmbH), 3.1 parts by weight of a commercial polyether (Pluriol® P900, available from BASF SE) and 1 Made 6.45 parts by weight of deionized water.

1 .2F Preparation of aqueous basecoats WBL B15 (comparison) and WBL B16 (according to the invention)

The components listed under "aqueous phase" in Table F are stirred together in the order indicated to give an aqueous mixture, which is then stirred for 10 minutes and adjusted to a pH of 8 and a spray viscosity of 1 liter using deionized water and dimethanolamine 0 ± 1 0 mPa-s (WBL B15) or 140 ± 1 0 mPa-s (WBL B16) at a shear stress of 1 000 s ^~ measured with a rotary viscometer (Rheolab QC with tempering system C-LTD80 / QC from the company Anton Paar) at 23 ° C.

Table F: Preparation of waterborne basecoats WBL B15 and WBL B16

WBL B15 WBL B16

Aqueous phase:

3% NaMg layered silicate solution 13.10

(vdM) 4 14,65

deionized water 10.53 16.33

n-propanol 0.87 0.87

n-Butoxypropanol 1.38 1.38

2-ethylhexanol 2.77 2.77

Aqueous dispersion of a poly (meth) acrylate emulsion polymer having a non-volatile content of

26-28% 35.24 35.24

Polyester; prepared according to Example D, column 16, Z. 37-59

DE 40 09 858 AI 2.95

Melamine-formaldehyde resin (esimene® HM 2608 of the company

Ineos) 4,10

10% dimethylethanolamine in water 0.30

2,4,7,9-tetramethyl-5-decynediol, 52% in BG (available from

BASF SE) 1.38 1.38 BYK-346, available from Altana / BYK-Chemie GmbH 0.46 0.46

Polyurethane-modified polyacrylate; made gi

7, Z. 55 to p. 8, Z. 23 of DE 4437535 AI 2,77 2,77

Isopropanol 1.64 1.64

Butyl glycol 1.00 1.00

Isopar® L, available from Exxon Mobile 0.87 0.87

NACU E 2500, available from King Industries, Inc. 0.42 0.42

Black paste 12,99 12,99

Blueprint 0.78 0.78

Barium sulphate paste 3.21 3.21

Steatite paste 3.25 3.25

Making black paste

Making blueprint

The blueprint was made from 69.8 parts by weight of a polyurethane dispersion prepared according to WO 92/15405, page 13, line 13 to page 15, line 13, 12.5 parts by weight of Paliogen® Blue L 6482 (available from BASF SE), 1, 5 Parts by weight of a 10% aqueous dimethylethanolamine solution, 1, 2 parts by weight of a commercially available polyether (Pluriol® P900, available from BASF SE) and 15 parts by weight of deionized water.

Preparation of barium sulfate paste

The barium sulfate paste is composed of 39 parts by weight of a polyurethane dispersion prepared according to EP 0228003 B2, page 8, lines 6 to 18, 54 parts by weight of barium sulfate (blanc fixe micro from Sachtleben Chemie GmbH), 3.7 parts by weight of butyl glycol and 0.3 part by weight Agitan 282 (available from Münzing Chemie GmbH) and 3 parts by weight of deionized water. Making steatite paste

The steatite paste is composed of 49.7 parts by weight of an aqueous binder dispersion prepared according to WO 91/15528, p. 23, line 26 to page 25, line 24, 28.9 parts by weight of steatite (Microtalc IT extra from Mondo Minerals BV), 0.4 parts by weight Agitan 282 (available from Münzing Chemie GmbH), 1.45 parts by weight Disperbyk®-184 (available from BYK-Chemie GmbH), 3.1 parts by weight of a commercial polyether (Pluriol® P900, available from BASF SE) and 1 Made 6.45 parts by weight of deionized water.

1 .2G Preparation of aqueous basecoats WBL B17 (comparison) and WBL B18 (according to the invention)

The components listed under "aqueous phase" in Table G are stirred together in the order indicated to form an aqueous mixture, and in the next step, an organic mixture is prepared from the components listed under "organic phase" in Table G and selected from "mixed lacquer". The organic mixture and the mixing varnish are mixed for 10 minutes before this mixture is then added to the aqueous mixture, then it is stirred for 1 0 minutes and brought to pH 8 with the aid of deionized water and dimethanolamine and a spray viscosity of 85 ± 5 mPa-s at a shear stress of 1000 s ^~ measured with a rotary viscometer (Rheolab QC device with tempering system C-LTD80 / QC Anton Paar) at 23 ° C, adjusted.

Table G: Preparation of waterborne basecoats WBL B17 and WBL B18

WBL B17 WBL B18

Aqueous phase: ^■

deionized water 16,48 29,34

Butyl glycol 5.78

(vdM) 6 22,96

Disparlon ^® A670-20M (direct addition) 3.44

Aqueous dispersion of a poly (meth) acrylate

Emulsion polymer with a non-volatile 32,26

Share of 26-28%

Polyester; prepared according to Example D, column 16, Z. 37-59

DE 40 09 858 AI Dimethylethanolamine in water (10% by weight) 0.80 0.91

Rheovis ^® AS 1130 0.75

2,4,7,9-Tetramethyl-5-decynediol in butyl glycol (52 wt%) 0.69

Resimene ^® HM 2608 4.36

Pluriol® ^® P900 1.15

Organic phase: ^·

Butyl glycol 6.89 6.89

Alu Stapa Hydrolux ^® VP56450 5.74 5.74

Mischlack:

Aqueous dispersion of a poly (meth) acrylate

Emulsion polymer with a non-volatile 1.89 1.89

Share of 26-28%)

deionized water 1.17 1.17

2,4,7,9-Tetramethyl-5-decynediol in butylglycol (52 wt%) 0.24 0.24

Dispex ^® Ultra FA 4437 0.10 0.10

Dimethylethanolamine in water (10% by weight) 0.01 0.01

Butyl glycol 0.60 0.60

2. Investigation of basecoats and Mehrschichtlackierunqen, which were prepared using the basecoats

Comparison between waterborne basecoat WBL B2 and waterborne basecoats WBL B1 and WBL B3 to WBL B6

The investigation was carried out with regard to the occurrence of specks, the tendency to segregation and the layer thickness-dependent course. The results are summarized in Tables 2.1 and 2.2.

Table 2.1: Results of investigations regarding stability (segregation) and specks WBL B1 WBL B2 WBL B3 WBL B4 WBL B5 WBL B6

Stability (Visual

Judgment of

segregation)

Speckling (coating

from glass panel)

Specks (coating

of steel substrate)

WBL B1 (containing phyllosilicate) and WBL B2 (to be used according to the invention) have no specks and also show no tendency to phase separation and segregation. The basecoats which have polyamides having a high acid number (WBL B3 to WBL B6) surprisingly show distinct weaknesses in terms of specks and stability; an increase in the amount of the polyamide leads to no improvement. These polyamides are therefore to be used as a rheology aid in waterborne paints significantly worse. As a reference for further investigations, therefore, the system containing phyllosilicate was used.

Table 2.2: Results of investigations with regard to progression (here: SW, LW and DOI)

characteristic value

Layer thickness range 2. Basecoat WBL Bl WBL B2 Appearance

5 μιτι - 10 μιτι 20.2 16.3

10 μιτι - 15 μιτι 19.2 17.6

15 μιτι - 20 μιτι 20.6 20.3

The results show that by using a basecoat to be used according to the invention, the course can be positively influenced, in particular in lower to middle layer thicknesses.

Comparison between water based paints WBL B7 and WBL B9 and the

Waterborne basecoats WBL B8 and WBL B10

The investigation was carried out with regard to the occurrence of pinholes and the layer thickness-dependent course. The results are summarized in Tables 2.3 to 2.5.

Table 2.3: Results of tests for pinholes

Number of pinholes (normalized to 200 cm ² ):

Layer Thickness Area Basecoat Total Layer

(Water-based paint 1 + water-based paint 2)

0-20 μιτι 0 0 0 0 20 μιτι - End of the wedge 0 0 0 0 Sum 0 o · ^" . ^·"·; O

Number of pinholes (normalized to 200 cm ² ):

Paint finish 2. Water-based paint as wedge WBL B7 = WBL BS WBL B9 WBL BIO

Layer Thickness Area Basecoat Total Layer

(Water-based paint 1 + water-based paint 2)

0-20 μm 0 0 0 20 μιτι - End of the wedge 0 0 0 Sum 0 0

The waterborne basecoats WBL B7 to WBL B10 consistently show a very good needle stick robustness.

Table 2.4: Results of the investigations concerning the course (here: SW, LW and DOI of the waterborne basecoat WBL B7 and WBL B8)

Table 2.5: Results of the investigations concerning course (here: LW of the aqueous basecoat WBL B9 and WBL B10)

Painting 1. Water-based paint as wedge WBL AI WBL AI

Painting 2. Water-based Laek constant WBL BS WBL BIO

characteristic value

Coating Thickness 2. Basecoat WBL B9 WBL BIO Appearance

5 μιτι - 10 μιτι 9.2 7.6

10 μιτι - 15 μιτι 9.6 7.4

15 μιτι - 20 μιτι 9.1 7.7

20 μιτι - 25 μιτι 10.2 8.1

25 μιτι - 30 μιτι 11.5 8.9 The results show that the course can be optimized by using the aqueous basecoat materials WBL B8 and WBL B10 according to the invention.

Comparison between waterborne basecoats WBL B1 1 and WBL B12

The investigation was carried out with regard to the storage stability and the layer thickness-dependent course. The results are summarized in Tables 2.6 and 2.7.

Table 2.6: Results of the tests with regard to storage stability

Water-based paint

WBL BU WBL B12

Niederscher- Frisch 3398.5 2456.7

Viscosity (1 s- ¹ ) after 2 weeks storage at 40 ° C 2811.2 2300

in mPa-s change [%] -17% -6%

Hochscher- Fresh 95.43 92.7

Viscosity (1000 s- ¹ ) after 2 weeks storage at 40 ° C 85.59 81.97 in mPa-s Change [%] -10% -12%

With regard to the change in the high-shear viscosity, both aqueous basecoats show comparable behavior. When using a basecoat material to be used according to the invention comprising a mixture (vdM) comprising a polyamide having a low acid number (WBL B12), a significant advantage with respect to the change in the low-shear viscosity is shown compared to the reference (WBL B11).

Table 2.7: Results of investigations with respect to layer thickness-dependent course (here: LW / DOI)

25 μιτι 30 μιτι 13.1 12.4

The results substantiate that a better course (determined here only LW and DOI) can be achieved when using a polyamide according to the invention with a low acid number in all layer thickness ranges.

Comparison between waterborne basecoats WBL B13 and WBL B14

The investigation was carried out with regard to the layer thickness-dependent course. The results are summarized in Table 2.8.

Table 2.8: Results of investigations with regard to coating thickness-dependent course (here: SW / LW / DOI)

25 μιτι - 30 μιτι 35.6 30.5

The use of a basecoat material to be used according to the invention comprising a predispersed mixture comprising a low acid number polyamide (WBL B14) in comparison with the layered silicate-containing reference (WBL B13) leads to a significant improvement in the course, in particular of short waves and of DOI.

Comparison between waterborne basecoats WBL B15 and WBL B1 6

The investigation was carried out with regard to the pinhole robustness and the layer thickness-dependent course. The results are summarized in Tables 2.9 to 2.1 1.

Table 2.9: Results of the investigations concerning pinholes

Number of pinholes (normalized to 200 cm ² ):

Painting 1. Water-based paint as wedge WBL AI WBL AI Paint finish 2. Water-based paint constant WBL BIS WBL BIS

Layer Thickness Area Basecoat Total Layer

(Water-based paint 1 + water-based paint 2}

0-20 μιτι

20 μιτι - end of the wedge

Total ..

Number of pinholes (normalized to 200 cm ² ):

Painting 1. Water-based paint constant WBL AI WBL AI

Paint finish 2. Water-based paint as wedge WBL to WBL B16

Layer Thickness Area Basecoat Total Layer

(Water-based paint 1 + water-based paint 2}

0-20 μm 63 0

20 μιτι - end of the wedge 21 0

Total ^{* * ':} 84 ^·' . ^' .: ^' . ^' . , Q

The aqueous basecoat WBL B16 to be used according to the invention has a significantly better pinhole robustness than the layered silicate-based waterborne basecoat WBL B15.

Table 2.10: Results of tests for pinholes

Number of pinholes (normalized to 200 cm ² ):

Paint finish 2. Water-based paint constant WBL B15 WBL BIß

Layer Thickness Area Basecoat Total Layer

(Water-based paint 1 + water-based paint 2)

0-20 μιτι 7 0

20 μιτι - end of the wedge 2 0

Total/, · . · ^· · 9/0 Number of pinholes (normalized to 200 cm ² ):

Paint finish 2. Water-based paint as wedge WBL to WBL B16

Sehichtdickenbereich base coat total layer

(Water-based paint 1 + water-based paint 2}

0-20 μm

20 μιτι - end of the wedge

total

When WBL A2 is used as the first aqueous basecoat, a significantly lower needle-point level is found for the layered silicate-containing reference (WBL B15); however, slight advantages in the use of the basecoat WBL B16 to be used according to the invention can still be seen.

Table 2.11: Results of investigations with regard to course (here: SW, LW and DOI)

30 μιτι - 40 μιτι 34.6 28.6

The results substantiate that advantages in the systems according to the invention are also achieved during the course, in particular at high layer thicknesses.

Comparison between waterborne basecoats WBL B17 and WBL B18

The investigation was carried out regarding the appearance of specks and the storage stability. The results are summarized in Tables 2.12 and 2.13. Table 2.12: Results of investigations on specks

WBL B17 WBL 18

Speckling (coating

of glass panel}

Speckling (coating

of steel substrate}

Table 2.13: Results of the tests with regard to storage stability

Water-based paint

WBL 817 WBL B18

Niederscher Fresh 3053 nm viscosity (1 s- ¹ ) after 2 weeks storage at 40 ° C 3177 nm in mPa-s Change [%] 4% nm

High shear Fresh 79 nm Viscosity (1000 s ^-1 ) after 2 weeks storage at 40 ° C 85 nm in mPa-s Change [%] 6% nm

The results show that the basecoat WBL B 17 to be used according to the invention has an outstanding quality in terms of storage stability and speck formation. In particular, it has been found that the use of a basecoat WBL B18, which contains the same low acid number polyamide as WBL B 17, but in which the polyamide is introduced directly and not in the form of a predispersed mixture (vdM), has markedly poorer properties.

Overall, the results show that the use of a polyamide having a low acid number in water-based paints surprisingly leads to significantly better properties than the use of polyamides having a higher acid number, which are actually intended for aqueous coating systems. However, these advantages are only obtained if the low-acid polyamide in the form of a predispersed mixture (vdM) is introduced into the aqueous basecoat. Brief description of the pictures

illustration 1

Schematic structure of a multi-layer coating (M) according to the invention arranged on a metallic substrate (S) comprising a cured electrodeposition coating layer (E.1) and a basecoat film (B.2.1) and a clearcoat film (K) which have been cured together.

Figure 2:

Schematic structure of a multi-layer coating (M) according to the invention arranged on a metallic substrate (S) comprising a cured electrodeposition coating layer (E.1), two basecoat films (B.2.2.x), namely a first basecoat film (B.2.2.a) and one above it arranged, topmost basecoat film (B.2.2.z), and a clearcoat film (K), which were cured together.

Figure 3:

Schematic structure of a multi-layer coating (M) according to the invention arranged on a metallic substrate (S) comprising a cured electrodeposition coating layer (E.1), three basecoat films (B.2.2.x), namely a first basecoat film (B.2.2.a), one above it arranged basecoat film (B.2.2.b) and a topmost basecoat film (B.2.2.z), and a clearcoat film (K), which were cured together.

Claims

claims

1 . A method for producing a multi-layer coating (M) on a metallic substrate (S) comprising

(1) production of a hardened electrodeposition coating layer (E.1) on the metallic substrate (S) by electrophoretic application of an electrodeposition paint (e.1) to the substrate (S) and subsequent hardening of the electrodeposition paint (e.1),

2. The method according to claim 1, characterized in that the at least one polyamide (P) has an acid number of less than 15 mg KOH per g.

3. The method according to claim 1 or 2, characterized in that the at least one polyamide (P) has an acid number of 0.1 to less than 15.0 mg KOH per g.

4. The method according to any one of claims 1 to 3, characterized in that the relative weight ratio of the at least one polymeric resin (H) and the at least one polyamide (P) in the mixture (vdM) in a range of 15: 1 to 2, 0: 1 is.

5. The method according to any one of claims 1 to 4, characterized in that the proportion of at least one predispersed mixture (vdM), based on the total amount of the basecoat (b.2.1) or the at least one basecoat (b.2.2.x), 5 to 30 wt .-%, wherein the at least one polyamide (P) in an amount of 0.15 to 3.0 wt .-%, based on the total amount of the basecoat (b.2.1) or the at least one basecoat ( b.2.2.x).

6. The method according to any one of claims 1 to 5, characterized in that in the mixture (vdM) as the polymeric resin (H) at least one polyester is contained, wherein the polyester has an acid number of 20 to 50 mg KOH per g and an OH Number of 20 to 300 mg KOH per g.

7. The method according to any one of claims 1 to 6, characterized in that the basecoat (b.2.1) or at least one of the basecoats (b.2.2.x), preferably all of the basecoats (b.2.2.x), at least one of the polymer comprising at least one polymeric resin (H) as a binder selected from the group consisting of hydroxy-functional polyurethanes, polyesters, polyacrylates and copolymers of these polymers.

8. The method according to any one of claims 1 to 7, characterized in that the basecoat (b.2.1) or at least one of the basecoats (b.2.2.x), preferably all of the basecoats (b.2.2.x), at least one melamine resin as Contains crosslinking agent.

9. The method according to any one of claims 1 to 8, characterized in that the basecoat (b.2.1) or at least one of the basecoats (b.2.2.x), preferably all of the basecoats (b.2.2.x), one-component coating compositions are.

10. The method according to any one of claims 1 to 19, characterized in that the common curing (4) is carried out at temperatures of 100 to 250 ° C for a period of 5 to 60 min.

1 1. Method according to one of claims 1 to 10, characterized in that the percentage sum of the solids and the proportion of water of the basecoat (b.2.1) or at least one of the basecoats (b.2.2.x), preferably all of the basecoats (b. 2.2.x), at least 70 wt .-%, preferably 80 to 90 wt .-%, is.

12. The method according to any one of claims 1 to 1 1, characterized in that the at least one predispersed mixture (vdM) contains at least one emulsifier (E) selected from the group consisting of lecithins and C12-C24 fatty alcohol polyglycol ethers.

13. The method according to any one of claims 1 to 12, characterized in that the at least one polyamide (P) has a number average molecular weight in a range of 250 g / mol to 3,000 g / mol.

14. The method according to any one of claims 1 to 13, characterized in that a car body is used as a metallic substrate.

15. Multi-layer coating (M), which was prepared by the method according to any one of claims 1 to 14.