EP2209859A1 - Coating agents based on incompatible polymers and electrically charged particles - Google Patents

Abstract

The invention relates to coating agents containing at least one polymer (P1), at least one polymer (P2) that is incompatible with polymer (P1) in the solid phase and/or a cross-linking agent (V) that is incompatible with polymer (P1) in the solid phase. Polymers (P1) and/or (P2) comprise at least one functional group (a) which reacts by forming covalent bonds when the coating agent is cured. The coating agent contains 0.1 to 30 percent by weight of electrically charged inorganic particles (AT) which have an average diameter (D) of <1 μm and in which the average ratio D/d between the average particle diameter (D) and the average particle thickness (d) is >50, the percentage by weight being in relation to the non-volatile components of the coating agent. The invention further relates to a method for producing OEM composite layers which are resistant to flying stones and consist of an anti-corrosive layer that is directly applied to the substrate, a filler layer, and a final layer of coating lacquer preferably consisting of a lacquer primer and a final clear lacquer layer, at least one layer being formed from the aforementioned coating agent.

Description

 Coating compositions based on incompatible polymers and electrically charged particles

The provision of impact-resistant coatings on metallic substrates is of particular importance in the automotive industry. A number of requirements are placed on a filler or a rockfall protection ground. Thus, after curing, the surfacer layer is said to have a high resistance to stone chips, in particular to multilayer coating, and at the same time a good adhesion to corrosion protection coating, in particular a cathodic electrocoat, and to the basecoat, good filling properties (covering the structure of the substrate) at layer thicknesses of about 20 to 35 .mu.m and cause a good Appearance in the final clear coat. Furthermore, suitable coating materials are preferably, in particular for ecological reasons, poor or largely free of organic solvents.

Coating compositions for fillers are known and described for example in EP-A-0 788 523 and EP-A-1 192 200. There, water-dilutable polyurethanes are described as binders for fillers, which are intended to ensure stone chip resistance, in particular with comparatively low layer thicknesses. When loaded in stone impact tests occur in the fillers of the prior art in OEM layer structures (corrosion protection layer (especially KTL) filler basecoat clearcoat) despite good stone chip resistance, ie a relatively small number of damage, but often damage to the paint layer in which the unprotected metal substrate is exposed by uncontrolled crack propagation in the OEM layer structure and subsequent delamination at the interface between metal and KTL. WO-A-01/04050 discloses inorganic anionic or cationic layer fillers for aqueous coating compositions having good barrier properties, which are modified with organic compounds for widening the spacing of the layers in the filler, which have at least two ionic groups are separated by at least 4 atoms. Double-layered hydroxides, in particular hydrotalcite types, can be used as cationic fillers. The coating compositions described in WO-A-01/04050 are used for coatings with very good barrier properties to gases and liquids, wherein the fillers are not intended to influence the curing process. A use of the coating compositions for improving the damage patterns after impact loading in OEM layer structures, in particular for the reduction of the exposed substrate surface, is not known.

Furthermore, it is known from scientific publications that the phase morphology of polymers can be influenced by the addition of nanoparticles. For example, N. Hasegawa et al. (Polym. Bull. 51 (2003), 77-83) and R. Krishnamoorti et al. (J. Chem. Phys. 115 (2001), 7166, ibidem 7175) reported on the control of the spatial arrangement of the microdomains of block copolymers by the presence of layered silicate particles as template. G. He et al. (J. Polym., Part B: Polym. Phys. 44 (2006), 2389) modeled the phase behavior of binary polymer blends in the presence of particles, inter alia, as a function of particle number, particle size, and affinity of the particle surface to the polymer components. The influence of phyllosilicates with different aspect ratios on the spinodal segregation behavior in the model system of polystyrene and polyvinyl methyl ether has been described by K. Yurekli et al. (Macromolecules 36 (2003), 7256.). All systems described so far are binary systems with defined polymers in terms of their molecular weight distribution. Such model polymers are synthetically complex to produce and due to their uniform primary structure (sequence of monomer units) not suitable as a coating agent for OEM layer structures.

WO-A-2005/052077 discloses coating compositions, in particular for the production of surfacer layers, which comprise a film-forming component comprising binder resin having functional groups and a crosslinker having at least two functional groups which after application and subsequent hardening in form a bicontinuous phase morphology of the cured layer. This is achieved by using preferably a water-dispersible polymer component which is incompatible with the polyurethane component in addition to the polyurethane component used as the binder resin in the film-forming component. The incompatibility of the polymer components is described by the interaction parameter x (Chi) according to the lattice model of Flory and Huggins, and by the correlation of the interaction parameter with the difference of the Hildebrand solubility parameter δ of the polymer components.

The coating compositions described in WO-A-2005/052077 have improved damage patterns as filler layer in OEM layer structures after curing. However, there is a need for further improvement of the stone chip resistance of surfacer layers and, in particular, for further improvement of the damage patterns. Furthermore, the setting of the bicontinuous morphology of the segregated phases in the hardened layer according to WO-A-2005/052077 is dependent not only on the thermodynamic influence of the interaction parameters of the binders x (chi). The Flory and Huggins model is limited to polymers without specific interactions such as hydrogen bonds or ionic attraction or repulsion, respectively (Paul J. Flory, Principles of Polymer Chemistry, Cornell University Press (New York), 1953). In the case of polyurethanes with NH groups capable of forming hydrogen bonds and with ion-forming groups, as used for formulating waterborne paints (see, for example, EP-A-0 788 523 and EP-A-1 192 200), both types of interaction are to be expected , As is known, hydrogen bonds in segmented polyurethanes lead to the formation of microdomains of the hard segments containing urethane groups (The Polyurethanes Book, Wiley, 2002 - ISBN 0470850418). G. Wilkes and A. Aneja (Polymer 44 (2003), 7221) were able to show, on the basis of segmented model polyurethanes, that the formation of hard microdomains can also take place without the presence of hydrogen bonds.

Furthermore, it is known that the spinodal separation of incompatible polymers is a function of temperature. Thus, a room-temperature-incompatible, spinodal-segregating polymer mixture can be compatible at higher temperatures and form a homogeneous phase (the system displays a so-called UCST = upper critical solution temperature) or vice versa (the system exhibits an LCST = lower critical solution temperature). The fillers described in WO-A-2005/052077 contain polymer blends whose phase behavior is not adequately described by Flory's enthalpic interaction parameter, moreover they are formulated into pigmented lacquers which can be characterized as microcomposites, ie they contain pigment particles on a micrometer scale in high pigment-to-binder (= polymer mixture) ratios. The resulting optical properties of the films of such systems excludes their broad applicability, for example in effect basecoats or clearcoats. From theoretical papers by A.Balasz and V.Ginzburg et al. (J. Polym. See Part B: Polym. Phys. 44 (2006), 2389 and J. Chem. Phys. 115 (2001), 3779) it is also known that the nodal demixing of binary polymer systems by the presence of particles as a function of other physical parameters (for example osmotic hydrodynamic effects) both hindered (eg immobile, non-neutral particles, ie particles with a Affinity for a polymer component, provide a thermodynamic barrier to the moving phase boundary) as well as being accelerated (mobile, non-neutral particles change to the phase to which their particle surface has a higher affinity). Moreover, the micro-meter scale pigments to be regarded as immobile particles of WO-A-2005/052077 act mechanically exclusively as a reinforcing component in the microcomposite, ie they lead to an increase in rigidity, measurable for example as an increased modulus of elasticity or as increased tensile strength. This property, which is positive for many applications, is of limited use for improving the resistance to chipping, since it is not only important for a projectile penetrating into the material to reduce its penetration depth through an increased resistance (= increased strength of the material) also to increase the toughness of matter displaced during penetration of the projectile, that is, its ability to dissipate the kinetic energy introduced without premature cracking and uncontrolled crack propagation leading to flaking of the paint material (delamination). Thus, D. Gersappe (Phys. Rev. Lett., 89 (2002), 058301) has shown that particles can increase the toughness of a given polymeric material, if they can be mobile in the polymer matrix on a timescale comparable to polymer motions. Works by B. Finnigan et.al. (Macromolecules 38 (2005), 7386) have also shown on nanocomposites of segmented polyurethanes and layered silicates that larger, immobile particles (clocks of silicates with a high aspect ratio) concentrate local mechanical stress and thus cavities in the adjacent matrix cause premature mechanical failure of the material.

The systems of the prior art described above all have an impact-sensitive and reproducible damage image under impact load, in particular when they are applied as thin layers or in layer structures, in particular in OEM layer structures, to impact-loaded substrates.

Task and solution

In the light of the prior art, the object of the present invention is to provide coating compositions which after hardening have a readily controllable and defined layer morphology. Preferably, the coating compositions, preferably based on ecologically advantageous aqueous coating materials, be used for impact-resistant coatings with a significantly improved damage pattern, in particular with a significant reduction of delamination of the OEM composite at the interface between metal and corrosion protection layer and thus with a significant reduction the exposed substrate surface after impact loading.

Surprisingly, it has been found that a coating composition comprising at least one polymer (P1), at least one incompatible with polymerizate (P1) in the solid phase polymer (P2) and / or with the polymer (P1) in the solid phase incompatible crosslinking agent (V ), wherein the polymers (P1) and / or (P2) have at least one functional group (a), which reacts with the curing of the coating agent to form covalent bonds, and 0.1 to 30 wt .-%, based on the nonvolatile Constituents of the coating agent, electrically charged inorganic particles (AT) whose average particle diameter (D), in the case of non-circular Particle diameter corresponds to the particle diameter of the longest surface diagonal of the particle, <1μm and whose average ratio D / d of the average particle diameter (D) to average particle thickness (d)> 50, the task of the invention solves outstanding.

Furthermore, a process has been found for the production of impact-resistant OEM layer composites consisting of a corrosion protection layer applied directly to the substrate, a filler layer, a basecoat film and a final clearcoat film, wherein at least one layer of the coating material of the invention is formed.

Description of the invention

As components essential to the invention, the coating composition of the invention contains at least one polymer (P1), at least one polymer (P1) incompatible with polymer (P1) in the solid phase and / or a crosslinking agent (V) which is incompatible with the polymer (P1) in the solid phase Polymers (P1) and / or (P2) have at least one functional group (a) which reacts on curing of the coating agent to form covalent bonds, and 0.1 to 30 wt .-%, based on the nonvolatile constituents of the coating composition , electrically charged inorganic particles (AT) whose average particle diameter (D) (in the case of non-circular particles corresponds to the particle diameter of the longest surface diagonal of the particle) <1μm and their average ratio D / d of the particle diameter (D) to the average particle thickness (d)> 50.

The polymer (P1) is incompatible with the polymer (P2) and / or with the crosslinking agent (V) in the solid phase, that is (P1) forms in thermodynamic equilibrium with (P2) and / or with (V) in a solid mixture phase interfaces.

According to the approach of Hildebrand for describing the compatibility between two polymers, the description of the interaction parameter x (Chi) is possible by the difference of the cohesive energy densities or the solubility parameter δ of the polymer components, which can be deduced from the quotient of the enthalpy of evaporation and the molar volume of the mixture components , Such solubility parameters δ alone involve the enthalpic interactions between the polymeric blend components, the preferred critical value for segregation of a binary polymer blend of components (P1) and (P2) or (P1) and (V) being the difference [ δ (P1) - δ (P2) and / or δ (V)] the solubility parameter according to Hildebrand δ (P1) of the polymer (P1) and δ (P2) of the polymer (P2) and / or δ (V) of the Crosslinking agent (V) to at least 1, preferably at least 1, 5, more preferably at least 2 can be defined (see also WO-A-2005/052077).

As polymers (P1) and (P2), in principle, all polymers are suitable which are incompatible. The polymers are preferably selected from the group of polyurethanes, polyesters, polyamides, polyethers, polyepoxides and / or polyacrylates, polyurethanes and / or polyesters being particularly preferred. The polymers (P1) and / or (P2) have at least one functional group (a) which reacts to form covalent bonds on curing of the coating agent.

The reaction of the functional groups (a) can be induced by radiation and / or thermally. Radiation-reactive groups (a) are usually groups which become reactive upon irradiation with actinic radiation and can preferably undergo reactions with other activated groups of their type to form covalent bonds which proceed according to a radical and / or ionic mechanism. Examples of suitable groups are CH single bonds, CC, CO, CN, CP or C-Si single or double bonds, with CC double bonds being preferred. In one embodiment of the invention, the radiation-crosslinkable groups (a) preferably react with themselves.

In the preferred embodiment of the invention, the reaction of the functional groups (a) is thermally induced, the groups (a) reacting with themselves, that is with further groups (a), and / or preferably with complementary functional groups (b) , The selection of the functional groups (a) and the complementary functional groups (b) depends firstly on the fact that they are used in the preparation of the polymers (P1) and / or (P2) and in the preparation, storage and application of the coating compositions no unwanted reactions, in particular no premature crosslinking, enter and secondly thereafter, in which temperature range the crosslinking should take place.

Examples of groups which react with themselves (a) are: methylol, methylol ether, N-alkoxymethylamino and in particular alkoxysilyl groups.

Examples of preferred pairs of groups (a) and complementary functional groups (b) according to the invention are: hydroxyl groups (a) with acid, acid anhydride, carbamate, optionally etherified methylol groups and / or optionally blocked isocyanate groups as functional group ( b), amino groups (a) with acid, acid anhydride, epoxy and / or isocyanate groups as functional Group (b), epoxy groups (a) having acid and / or amino groups as the functional group (b), and mercapto groups (a) having acid, acid anhydride, carbamate and / or isocyanate groups as the functional group (b). In a particularly preferred embodiment of the invention, the complementary functional groups (b) are part of a crosslinking agent (V), which is described below.

In particular, hydroxyl, amino and / or epoxy groups are preferred as groups (a). Particularly preferred groups (a) are hydroxyl groups, where the OH numbers of the polymers (P1) and / or (P2) according to DIN EN ISO 4629 are preferably between 10 and 200, more preferably between 15 and 150.

The functional groups (a) are introduced into the polymers (P1) and / or (P2) via the incorporation of suitable molecular units in a manner known to the person skilled in the art.

In a preferred embodiment of the invention, the polymers (P1) and / or (P2), preferably (P1) and (P2), water-dispersible polymers (WP1) and / or (WP2) and in particular selected from the group of water-dispersible polyurethanes , Polyesters, polyamides, polyethers, polyepoxides and polyacrylates, with water-dispersible polyurethanes and / or polyesters being very particularly preferred.

For the purposes of the invention, water-dispersible means that the polymers (WP1) and / or (WP2) in the aqueous phase form aggregates having an average particle diameter of preferably <500, more preferably <200 and most preferably <100 nm, or are dissolved in a molecular dispersion. The size of the aggregates consisting of polymer (WP1) and / or (WP2) can be prepared in a manner known per se by introduction of hydrophilic groups on the polymer (WP1). and / or (WP2) be accomplished. The water-dispersible polymers (WP1) and / or (WP2) preferably have mass-average molecular weights Mw (determinable by gel permeation chromatography with polystyrene as standard) of from 1,000 to 100,000 daltons, more preferably from 1,500 to 50,000 daltons.

The preferred water-dispersible polyurethanes (WP1) and / or (WP2) can be prepared from building blocks, as described, for example, in DE-A-35 45 618 or DE-A-40 05 961. Into the polyurethane molecules are preferably incorporated groups capable of forming anions which, after neutralization, ensure that the polyurethane resin can be stably dispersed in water. Suitable groups capable of forming anions are preferably carboxyl, sulfonic acid and phosphonic acid groups, more preferably carboxyl groups. The acid number of the water-dispersible polyurethanes (WP1) and / or (WP2) according to DIN EN ISO 3682 is preferably between 10 and 80 mg KOH / g, more preferably between 20 and 60 mg KOH / g. To neutralize the groups capable of forming anions, preference is given to using ammonia, amines and / or amino alcohols, for example di- and triethylamine, dimethylaminoethanolamine, diisopropanolamine, morpholines and / or N-alkylmorpholines. Hydroxyl groups are preferably used as the functional group (a), the OH numbers of the water-dispersible polyurethanes (WP1) and / or (WP2) according to DIN EN ISO 4629 preferably being between 10 and 200 and particularly preferably between 15 and 150.

Particularly preferred water-dispersible polyurethanes (WP1) and / or (WP2) are composed of hydroxy-functional polyester precursors, which gene preferably with mixtures of Bisisocyanatoverbindun-, such as, preferably hexamethylene diisocyanate, isophorone diisocyanate, TMXDI, 4,4 ^{'methylene-bis-} (cyclohexyl isocyanate), 4 ^' 4'-methylene-bis (phenyl isocyanate), 1, 3-bis (1-isocyanato-1-methylethyl) benzene) and compounds capable of forming anions, in particular 2,2-bis (hydroxymethyl) propionic acid, are converted to the polyurethane. Optionally, the polyurethanes can be branched by the proportionate use of polyols, preferably triols, more preferably 1,1,1-tris (hydroxymethyl) propane, corresponding to 0 to 40, preferably 0 to 30, mol% of the equivalents of hydroxyl groups used being constructed. The hydroxy-functional polyester precursors are preferably composed of diols and dicarboxylic acids, as described, for example, in DE-A-36 36 368 or DE-A-40 05 961. Particular preference is given to using mixtures of aromatic and / or aliphatic dicarboxylic acids and of aliphatic diols, where from 10 to 90 mol%, preferably from 20 to 80 mol%, based on the dicarboxylic acid and / or the diol mixture, of dicarboxylic acids and / or or diols which have at least one aliphatic side group consisting of at least 6 carbon atoms.

The water-dispersibility of the polyurethanes is achieved by neutralization of the groups capable of anion formation, preferably with amines, more preferably with diethanolamine, with a degree of neutralization of between 80 and 100%, based on the total of neutralizable groups, being preferred.

The preferred water-dispersible polyesters (WP1) and / or (WP2) can be prepared from building blocks, as also described, for example, in DE-A-36 36 368 or DE-A-40 05 961. In the polyester molecules are preferably incorporated groups capable of forming anions, which after their neutralization ensure that the polyester resin can be stably dispersed in water. Suitable groups capable of forming anions are preferably carboxyl, sulfonic acid and phosphonic acid groups, more preferably carboxyl groups. The acid number DIN EN ISO 3682 of the polyester resins is preferably between 10 and 100 mg KOH / g, more preferably between 20 and 80 mg KOH / g. For neutralization of For the formation of anions capable groups are preferably also ammonia, amines and / or amino alcohols such as di- and triethylamine, dimethylaminoethanolamine, diisopropanolamine, morpholines and / or N-alkylmorpholines used. Hydroxyl groups are preferably used as the functional group (a), the OH numbers DIN EN ISO 4629 of the water-dispersible polyester preferably being between 10 and 200 and more preferably between 20 and 150. Particularly preferred water-dispersible polyesters (WP1) and / or (WP2) are composed of hydroxy-functional polyester precursors of mixtures of aromatic and aliphatic dicarboxylic acids with mixtures of aliphatic diols and polyols, preferably triols, preferably 1,1,1-tris (hydroxymethyl) - Propane representable. The polyols are preferably used in stoichiometric excess, so that the polyester precursors preferably have acid numbers of less than 1 and hydroxyl numbers of between 100 and 500. The molecular weights are preferably between 300 and 1,000. The water-dispersible polyesters are obtained by esterification of the polyester precursors with compounds capable of forming anions, in particular 1, 2,4-benzenetricarboxylic anhydride. The water-dispersibility of the polyesters is preferably achieved by neutralization of the groups capable of forming anions, preferably with amines, more preferably with diethanolamine, a degree of neutralization of between 80 and 100%, based on the total of the neutralizable groups, being preferred.

The polymers (P1 and (P2) are preferably present in the coating material according to the invention in proportions of from 10 to 95% by weight, preferably from 20 to 80% by weight, based on the non-volatile constituents of the coating agent. The crosslinking agent (V) used in the preferred embodiment of the invention has at least two crosslinkable functional groups (b) which are used as complementary functional groups with the functional groups (a) of the polymers (P1) and (P2) or (WP1) and (WP2) and / or other constituents of the binder upon curing of the coating agent to form covalent bonds. The functional groups (b) can be reacted by radiation and / or thermally. Preference is given to thermally crosslinkable groups (b).

Preference is given in the crosslinking agent (V) to thermally crosslinkable groups (b) which react with the preferred functional groups (a) selected from the group of the hydroxyl, amino and / or epoxy groups. Particularly preferred complementary groups (b) are selected from the group of the carboxyl groups, the optionally blocked polyisocyanate cyanate groups, the carbamate groups and / or the methylol groups, which are optionally partially or completely etherified with alcohols.

Very particular preference is given in the crosslinking agent (V) to functional complementary groups (b) which react with the particularly preferred hydroxyl groups as functional groups (a), where (b) is preferably selected from the group of the optionally blocked polyisocyanate groups and / or the methylol groups, which may be partially or completely etherified with alcohols.

The crosslinking agent (V) is present in the coating composition preferably in proportions of from 5 to 60% by weight, preferably from 10 to 50% by weight, based on the nonvolatile constituents of the coating composition.

In a preferred embodiment of the invention, the crosslinking agent V is selected from the group of water-dispersible Crosslinking agent (WV). To prepare such water-dispersible crosslinking agents (WV), the above-described groups capable of forming anions are preferably incorporated into the crosslinker molecules, which after their neutralization ensure that the crosslinking agent (WV) can be stably dispersed in water. Suitable groups capable of forming anions are preferably carboxyl, sulfonic acid and phosphonic acid groups, more preferably carboxyl groups. In order to neutralize the groups capable of forming anions, it is also preferable to use the abovementioned ammonia, amines and / or amino alcohols in the amounts described above.

Examples of polyisocyanates which are suitable as preferred crosslinking agents (V) and suitable blocking agents are described, for example, in EP-A-1 192 200, where the blocking agents have in particular the function of preventing an undesired reaction of the isocyanate groups with the reactive groups (a) of the polymers ( P1) and / or (P2) or (WP1) and / or (WP2) and with further reactive groups and with the water in the coating agent before and during application. The blocking agents are selected in such a way that the blocked isocyanate groups deblock again only in the temperature range in which the thermal crosslinking of the coating agent is to take place, in particular in the temperature range between 120 and 180 degrees C, and undergo crosslinking reactions with the functional groups (a).

Particularly preferred polyisocyanates as crosslinking agents (V) are selected from the group of water-dispersible polyisocyanates (WV) which are prepared by reacting polyisocyanates, preferably the isocyanurate-trimerized hexamethylene diisocyanate or isophorone diisocyanate, with compounds capable of forming anions, preferably 2,2-bis- (hydroxymethyl) propionic acid, and the blocking agent, such as preferably 3,5-dimethylpyrazole, diethyl malonate or O- xime, more preferably butanone oxime, can be obtained. The molar ratio of polyisocyanate, preferably trimerized diisocyanate, to the compound capable of forming anions, preferably 2,2-bis (hydroxymethyl) propionic acid, is preferably between 1: 1 and 2: 1, more preferably between 1.1: 1 and 1, 5: 1.

Examples of components containing methylol groups as preferred crosslinking agents (V) are, in particular, water-dispersible aminoplast resins (WV) _1, as described, for example, in EP-A-1 192 200. It is preferred to use aminoplast resins, in particular melamine-formaldehyde resins, which react with the functional groups (a), in particular with hydroxyl groups, in the temperature range between 100 and 180.degree. C., preferably between 120 and 160.degree. Particularly preferred aminoplast resins as crosslinking agents (V) or (WV) are selected from the group of hexamethoxymethyl-melamine-formaldehyde resins.

In a very particularly preferred embodiment of the invention, as crosslinking agents (V) and / or (WV), combinations of the abovementioned blocked polyisocyanates with the abovementioned amino resins are used. The mixing ratio of the blocked polyisocyanates to the aminoplast resins is preferably between 4: 1 and 1: 4, preferably between 3: 1 and 1: 3 (ratio of the non-volatile components of both components).

In the coating composition according to the invention are from 0.1 to 30 wt .-%, preferably between 0.5 and 25 wt .-%, particularly preferably between 1 and 20 wt .-%, based on the non-volatile constituents of the coating agent, electrically charged inorganic Particles (AT) contain their mean particle diameter (D), in the case of non-circular particles the particle diameter corresponds to the longest surface diagonal of the particle, D <1 μm and their ratio D / d of average particle diameter (D) to the average particle thickness (d)> 50, preferably D / d> 100, more preferably D / d> 200, and whose charge is compensated with inorganic and / or organic counterions (GI). The mean particle diameters can be determined by the evaluation of TEM (Tunnel Electron Microscope) images, while the particle thicknesses (d) are determined experimentally by X-ray structure analysis, AFM (Atomic Force Microscopy) profile measurements on single platelets and computational knowledge of the molecular structure , The average particle diameter (D) of the electrically charged inorganic particles (AT) is preferably between 50 and 800 nm, more preferably between 100 and 500 nm, and the particle thickness (d) is preferably between 0.1 and 1.0 nm, especially preferably between 0.15 and 0.75 nm.

The number and mobility of the particles required for the control of the phase morphology can be controlled with the aforementioned particles, depending on whether they are dispersed as individual particles dispersed in the matrix (exfoliated state), as individually dispersed stacks with plane-parallel individual particles comprising polymeric matrix material between the individual particles (intercalated state) or as sparsely dispersed agglomerates of stacks of the individual particles are distributed into the organic matrix.

Usually, the layer distances between the electrically charged inorganic particles determined by X-ray diffraction are indicated. The layer spacing comprises the sum of the layer thickness (d) of a particle and the distance between two such particles. The latter is dependent on the nature of the counterions therein, which neutralize the electrical charge carriers of the particles, and on the presence of swelling electrically neutral molecules, such as water or organic solvents. It is known, for example, that the layer spacing in montmorillonite as a function of Water content of most naturally occurring environmental conditions varies between 0.97 and 1.5 nm (J. Phys. Chem. B, 108 (2004) 1255).

In one embodiment of the invention, the preparation of the electrically charged inorganic particles (AT) can be carried out by exchanging the naturally occurring or the synthesis-related counterions of the layered minerals with the inorganic and / or organic counterions (GI) according to methods known per se. For this example, the electrically charged inorganic particles (AT) in a suitable liquid medium, which is able to swell the interstices between the individual layers and in which the inorganic and / or organic counterions (GI) are dissolved, suspended and subsequently isolated again (Langmuir 21 (2005), 8675).

In the ion exchange, preferably more than 15 mol%, particularly preferably more than 30 mol%, of the synthesis-related counterions are replaced by the inorganic and / or organic counterions (G1). Depending on the size and the spatial orientation of the counterions (G1), the layer structures are generally widened, wherein the distance between the electrically charged layers is preferably widened by at least 0.2 nm, preferably by at least 0.5 nm. The inorganic and / or organic counterions (GI) used for at least partial compensation of the charge and for widening the layers of the inorganic particles (AT) are constructed as follows. The charge carriers are preferably cationic and / or anionic groups, such as in the case of the organic counterions (G) preferably alkyl-substituted sulfonium and / or phosphonium ions, which preferably do not cause discoloration of the layer upon curing of the layer produced according to the invention, and preferably anions as anions the carboxylic acid, the sulfonic acid and / or the phosphonic acid. In the case of the inorganic counterions (GI), alkali metal and alkaline earth metal ions preferably function as charge carriers and, as anions, preferably anions of mineral acids, which likewise preferably do not cause discoloration of the layer when the layer produced according to the invention is cured.

Examples of suitable substances for the preparation of the inorganic particles (AT) are clay minerals, in particular naturally occurring smectite types, such as montmorillonite, saponite, hectorite, fluorohectocrite, beidellite, nontronite, vermiculite, halloysite and stephanite or synthetically produced smectite types, such as Laponite or SOMASIF (synthetic fluorinated sheet silicate from CO-OP Chemical Co., Japan). The abovementioned minerals have a negative surface charge which is compensated by positively charged inorganic and / or organic counterions (G1).

Particularly preferred for the purposes of the invention are cationically charged inorganic particles (AT), in particular the mixed hydroxides of the formula:

(M _{( 1.x)} ²⁺ M _x ³⁺ (OH) ₂ ) (A _{x / y} ^y -) n H ₂ O

where M ^{2+ are} divalent cations, M ^{3+ are} trivalent cations and (A) are anions of valency y, where x is from 0.05 to 0.5.

Particularly preferred divalent cations M ²⁺ calcium, zinc and / or magnesium ions and / or as trivalent cations M ³⁺ aluminum ions and / or as anions (A) phosphate ions, sulfate ions and / or carbonate ions, because these ions largely ensure that no change in hue occurs during curing of the layer according to the invention. The synthesis of the mixed hydroxides is known (E. Kanezaki, Preparation of Layered Double Hydroxides in terface Science and Technology, VoM, Chapter 12, 345ff - Elsevier, 2004, ISBN 0-12-088439-9). It usually takes place from the mixtures of the salts of the cations in the aqueous phase at defined, constant basic pH values. The mixed hydroxides containing the anions of the metal salts are obtained as inorganic counterions embedded in the interstices. The synthesis in the presence of carbon dioxide is usually obtained the mixed hydroxide with embedded carbonate ions. If the synthesis is carried out in the absence of carbon dioxide or carbonate in the presence of organic anions or their acid precursors, the mixed hydroxide with intervening organic anions (coprecipitation method or template method) is generally obtained. An alternative synthetic route for the preparation of the mixed hydroxides consists either in the hydrolysis of the metal alcoholates in the presence of the desired anions to be incorporated (US Pat. No. 6,514,473).

In a further embodiment of the invention, it is possible to carry out the incorporation of the inorganic and / or organic anions as counterions (G1) by ion exchange on mixed hydroxides with incorporated carbonate ions. This can be done, for example, in particular in the preparation of hydrotalcites and hydrocalumites by rehydration of the amorphous calcined mixed oxide in the presence of the desired anions to be deposited. The CaI- cination of the mixed hydroxide, containing embedded Carbona- tions, at temperatures <800 ⁰ C provides the amorphous mixed oxide to obtain the layer structures.

Alternatively, the ion exchange can be carried out in an aqueous or alcoholic aqueous medium in the presence of the acid precursors of the organic anions to be stored. Depending on the acidity of the precursor of the inorganic and / or organic anion to be incorporated, it is necessary to treat it with dilute mineral acids as counterion (GI) in order to remove the carbonate ions. The organic anions (OA) used as counterions (GI) in one embodiment of the invention for at least partial compensation of the charge and for widening the layers of the abovementioned mixed hydroxides are preferably simply charged. The charge carriers are preferably anionic groups (AG), particularly preferably anions of the carboxylic acid, the sulfonic acid and / or the phosphonic acid. In a further preferred embodiment of the invention, the organic anions (OA) carry, as counterions (G1), additionally functional groups (c) which react with the functional groups (a) of the binder BM and / or the functional groups (b) of the crosslinker during curing react the coating agent to form covalent bonds. The groups (c) can be radiation and / or thermally curable. Preference is given to thermally curable groups (c), as listed above in the description of groups (a) and (b). The functional groups (c) are particularly preferably selected from the group of hydroxyl, epoxy and / or amino groups. The functional groups (c) are preferably separated from the anionic groups of the organic anions (OA) as counterions (GI) by a spacer (SP), where (SP) is selected from the group optionally containing heteroatoms, such as nitrogen, oxygen and or sulfur, modified and optionally substituted aliphatic and / or cycloaliphatic compounds having a total of 3 to 30 carbon atoms, preferably between 4 and 20 carbon atoms, more preferably between 5 and 15 carbon atoms, optionally with heteroatoms such as nitrogen, oxygen and / or or sulfur, modified and optionally substituted aromatics having a total of 3 to 20 carbon atoms, preferably between 4 and 18 carbon atoms, more preferably between 5 and 15 carbon atoms, and / or the partial structures of the abovementioned cycloaliphatic and aromatic compounds, wherein in the substructures in particular at least 3 coal atoms and / or heteroatoms between the functional group (c) and the anionic group (AG) are located. Particular preference is given to the spacers (SP) of the organic anions (OA) as counterions (G) which are optionally substituted phenyl or cyclohexyl radicals which contain the functional group (c) in m- or p-

Position to the anionic group (AG) have. In particular, carboxyl group and / or sulfonate groups are used here as functional group (c) hydroxyl and / or amino groups and as anionic group (AG). Very particularly preferred as organic anions (OA) as counterions (G) are m- or p-aminobenzenesulfonate, m- or p-hydroxybenzenesulfonate, m- or p-aminobenzoate and / or m- or p-hydroxybenzoate.

In the case of the abovementioned particularly preferred mixed hydroxides, which, as a result of the synthesis, preferably contain carbonate as anion (A), preferably more than 15 mol%, particularly preferably more than 30 mol%, of the anions (A) are replaced by the organic anions during ion exchange ( OA) replaced as counterions (GI).

The modification of the cationically charged inorganic particles (AT) is preferably carried out in a separate process prior to incorporation into the coating composition according to the invention, this process being particularly preferably carried out in an aqueous medium. The electrically charged inorganic particles (AT) modified with the organic counterions are preferably prepared in a synthesis step. The particles thus produced have only a very low intrinsic color, they are preferably colorless. The preferred cationically charged particles modified with organic anions (OA) as counterions (GI) can be prepared in a synthesis step, in particular from the metal salts of the cations and the organic anions (OA). ne aqueous alkaline solution of the organic anions (OA) as counter ions (GI) an aqueous mixture of salts of divalent cations M ²⁺ and the trivalent cations M ³⁺ registered until the desired stoichiometry is set. The addition is preferably carried out under CO ₂ -free atmosphere, for example nitrogen and stirring at temperatures between 10 and 100 degrees C, preferably at room temperature, wherein the pH of the aqueous reaction mixture, preferably by adding alkaline hydroxides, preferably NaOH, in the range of 8 to 12, preferably between 9 and 11 is maintained. After addition of the aqueous mixture of the metal salts, the resulting suspension is aged at the abovementioned temperatures over a period of 0.1 to 10 days, preferably 3 to 24 hours, the resulting precipitate, preferably by centrifugation, isolated and washed several times with deionized water , Thereafter, a suspension of the cationically charged particles (AT) modified with the organic anions (OA) as counterions (GI) with a solids content of from 5 to 50% by weight, preferably from 10 to 40% by weight, of the purified precipitate with water .-%, discontinued.

The crystallinity of the layered double hydroxides obtained depends on the chosen synthesis parameters, the type of cations used, the ratio of the M ² VM ³⁺ cations and the type and amount of anions used and should be as large as possible. The crystallinity of the mixed hydroxide phase can be expressed as the calculated size of the coherent scattering domains from the analysis of the corresponding X-ray diffraction lines, eg the reflections [003] and [110] in the case of the Mg-Al hydrotalcite. For example, Eliseev et al. (Doklady Chemistry 387 (2002), 777) explain the influence of thermal aging on the increase in the domain size of the investigated Mg-Al hydrotalcite and explain this with the progressive incorporation of remaining existing tetredrically coordinated aluminum into the mixed hydroxide layer as octahedrally coordinated aluminum, as evidenced by the relative intensities of the corresponding signals in the ²⁷ Al NMR spectrum.

The electrically charged inorganic particles (AT) or the above-described suspensions of the electrically charged inorganic particles (AT) can in principle be incorporated during each phase in the process according to the invention for preparing the coating composition, that is before, during and / or after the addition of the remainder Components of the coating agent.

For controlling the phase morphology of the thin films, a difference in the affinity of the electrically charged inorganic particles (AT) for the incompatible polymers (P1), (P2) and / or the crosslinking agent (V) is preferred. In a particularly preferred embodiment of the invention, at least one component from the group (P1), (P2) and (V) has a difference in hydrophilicity compared with the other components, preferably by a suitable selection of the components of the polymers described above (P1) or (WP1), (P2) or (WP2) and the crosslinker (V) or (WV) is set. In a very particularly preferred embodiment of the invention, the polymer (P1) or (WP1) is more hydrophobic than the polymer (P2) or (WP2) and / or the crosslinking agent (V) or (WV), wherein as polymers (P1) or (WP1) polyurethanes and as polymers (P2) or (WP2) polyesters and as crosslinking agents (V) or (VW) polyisocyanates and / or aminoplast resins are particularly preferred. Depending on their surface condition, the electrically charged inorganic particles (AT) accumulate in the more hydrophilic or hydrophobic phase. The surface condition of the electrically charged inorganic particles (AT) is preferably controlled by the ion exchange capacity of the particles (AT) and / or by the selection of the counterions (G1). The ion exchange capacity is set, for example, in the preferred mixed hydroxides by the ratio of divalent to trivalent cations, which is more preferably between 1: 1 and 4: 1.

Furthermore, small, preferably inorganic counter ions with high charge density, such as particularly preferred ammonium, alkali metal or alkaline earth metal ions as cations, and particularly preferably phosphate ions, sulfate ions or carbonate ions as anions, cause the formation of a hydrophilic surface of the particles (AT) and thus cause greater affinity to the hydrophilic phase. Larger, preferably organic, counter ions having a comparatively lower charge density, such as particularly preferably tetraalkylammonium ions, trialkylsulfonium ions or tetraalkylphosphonium ions as cations, and particularly preferably organic anions of the carboxylic acid, the sulfonic acid and / or the phosphonic acid, in particular the above-described organic counterions, which are suitable for modifying the Particularly preferred cationically charged inorganic anisotropic particles (AT) are used, usually cause the formation of a hydrophobic surface and thus a greater affinity for the hydrophobic phase.

By a suitable selection of the mixing ratio of the more hydrophilic component, preferably formed from the polymer (P2) or (WP2) and / or the crosslinking agent (V) or (WV), to the more hydrophobic component, preferably formed from the polymer (P1) or (WP1 ), and by appropriate selection of anisotropic particles (T) having a hydrophilic or hydrophobic surface, disperse, bicontinuous or macroscopically stratified in two layers, or an organized layer structure in thin layers Layers are made. In a preferred embodiment of the invention, a mixing ratio of hydrophilic components to hydrophobic components of 10: 1 to 0.2: 1, more preferably from 6: 1 to 1: 1, is selected. Upon addition of electrically charged particles, preferably cationically charged inorganic anisotropic particles (AT), particularly preferably mixed hydroxides of the aforementioned formula, in combination with anions as counterions (G1) with high charge density, in particular with carbonate anions, bicontinuous results after the coating agent has cured or macroscopically in two layers stratified structures, while in the case of the combination of cationically charged inorganic anisotropic particles (AT), more preferably the mixed hydroxides of the aforementioned formula, with anions as counterions (GI) with lower charge density, in particular m- or p -Aminobenzolsulfonat, m- or p-hydroxybenzenesulfonate, m- or p-aminobenzoate and / or m- or p-hydroxybenzoate, disperse or bicontinuous structures result.

All of the structures produced in this way have in common that they have a significantly improved damage pattern compared with the prior art, in particular with regard to the reduction of the delamination of the layer and with regard to the proportion of the completely removed layer, after impact loading.

In addition to the abovementioned components essential to the invention, the coating composition according to the invention may contain further, optionally water-dispersible binders in proportions of up to 40% by weight, preferably of up to 30% by weight and more preferably of up to 20% by weight, based on the non volatile constituents of the coating agent. The coating composition according to the invention may also contain paint additives in effective amounts. Thus, for example, pigments and effect pigments in customary and known amounts may be part of the coating composition. The pigments can consist of organic or inorganic compounds and are listed by way of example in EP-A-1 192 200. Further usable additives are, for example, UV absorbers, radical scavengers, slip additives, polymerization inhibitors, defoamers, emulsifiers, wetting agents, leveling agents, film-forming auxiliaries, rheology-controlling additives and preferably catalysts for the reaction of the functional groups a, b and / or c, and additional crosslinking agents for the functional groups a, b and / or c. Further examples of suitable paint additives are described, for example, in the textbook "Lackadditive" by Johan Bieleman, Verlag Wiley-VCH, Weinheim, New York, 1998. The abovementioned additives are preferably present in the coating composition according to the invention in proportions of up to 40% by weight, preferably to 30 wt .-% and particularly preferably from to 20 wt .-%, based on the nonvolatile constituents of the coating composition.

The preferably aqueous coating compositions according to the invention are preferably prepared by first mixing all constituents of the coating composition apart from the modified inorganic particles and the preferably used aminoplast component of the crosslinking agent (V) or (WV). The suspension of the electrically charged inorganic particles (AT) optionally modified with the organic counterions (OG) is added to the resulting mixture while stirring until the suspension is completely dissolved, as determined by optical methods, in particular by visual methods Appraisal, followed.

The resulting mixture is preferably heated at temperatures between 10 and 50 degrees C for a period of 2 to 30 minutes, preferably from 5 to 20 minutes, preferably at room temperature, treated with ultrasound while stirring, wherein in a particularly preferred embodiment, the tip of an ultrasonic source is immersed in the mixture. During the ultrasonic treatment, the temperature of the mixture may rise by 10 to 60K. The dispersion thus obtained is preferably aged for at least 12 hours with stirring at room temperature. Thereafter, the crosslinking agent (V) or (WV) is added with stirring and the dispersion is preferably adjusted with water to a solids content of 15 to 50 wt .-%, preferably 20 to 40 wt .-%.

The coating materials of the invention are preferably applied in such a wet film thickness that after curing in the finished layers, a dry film thickness between 1 and 100 .mu.m, preferably between 5 and 75 .mu.m, more preferably between 10 and 60 A / m, in particular between 15 and 50 microns results.

The application of the coating agent in the process according to the invention can be carried out by customary application methods, such as, for example, spraying, knife coating, brushing, pouring, dipping or rolling. Preferably, spray application methods are used, such as compressed air spraying, airless spraying, high rotation spraying and electrostatic spraying (ESTA). The application is usually carried out at temperatures of a maximum of 70 to 80 degrees C, so that suitable application viscosities can be achieved without a change or damage of the coating agent and its optionally reprocessed overspray occurs during the momentarily acting thermal load. The radiation curing of the applied layer with the coating composition according to the invention with groups which can be crosslinked by radiation is carried out with actinic radiation, in particular with UV radiation. preferably in an inert atmosphere, as described for example in WO-A-03/016413.

The preferred thermal curing of the applied layer of the coating composition of the invention with thermally crosslinkable groups is carried out by the known methods, such as by heating in a convection oven or by irradiation with infrared lamps. Advantageously, the thermal curing is carried out at temperatures between 100 and 180 degrees C, preferably between 120 and 160 degrees C ₁ for a time between 1 minute and 2 hours, preferably between 2 minutes and 1 hour, more preferably between 3 and 30 minutes. If substrates, such as metals, are used, which are highly resistant to high temperatures, the curing can also be carried out at temperatures above 180 ° C. In general, however, temperatures of 160 to 180 degrees C should not be exceeded. If, on the other hand, substrates are used, such as plastics, which can only be thermally loaded to a maximum limit, the temperature and the time required for the curing process must be matched to this maximum limit.

Within the scope of the present invention, it has also been found that the exposed substrate surface can be considerably reduced after impact loading of substrates coated with OEM layer assemblies when the coating compositions described above are used.

Very particular preference is given to the use of the abovementioned coating compositions for producing surfacer layers which, after impact exposure, have a significantly reduced exposure of the substrate surface. Especially in classic OEM OEM paint systems, in which on the metallic substrate and / or a plastic substrate, a multilayer structure consisting of an electrodeposited layer, seen from the substrate, preferably a cathodically deposited layer, a surfacer layer, and a final topcoat layer, preferably consisting of a basecoat layer and a final clearcoat layer is applied, filler layers prepared from the coating compositions of the invention are particularly advantageous.

In a preferred method, the coating agent according to the invention is applied to a substrate precoated with an electrodeposition coating layer. Particularly preferred is the coating of metal and / or plastic substrates, which are precoated with a cathodic dip. The electrocoat material, in particular the cathodic dip paint, is preferably cured before application of the coating composition according to the invention. In a further preferred method, a final topcoat is applied to the layer formed from the coating composition of the invention, preferably a basecoat and finally a clearcoat, preferably in two further stages. In a particularly preferred process, the layer of the coating composition according to the invention is first cured and then preferably applied in a first step, an aqueous basecoat and after a Zwischenabüftung for a time between 1 to 30 minutes, preferably between 2 and 20 minutes, at temperatures between 40 and 90 degrees C, preferably between 50 and 85 degrees C, and in a second step with a clearcoat, preferably a two-component clearcoat, overcoated, wherein the basecoat and clearcoat are cured together.

In a further preferred embodiment of the invention, the filler layer produced with the coating composition according to the invention before applying the basecoat film for a time between 1 to 30 minutes, preferably between 2 and 20 minutes, at temperatures between 40 and 90 degrees C, preferably between 50 and 85 Degassed grade C. After that, filler layer, basecoat layer and clearcoat layer are cured together.

The coatings produced with the coating composition according to the invention, in particular the OEM structures, consisting of an electrodeposited corrosion protection layer from the substrate, from the filler layer produced with the coating composition according to the invention and a final topcoat layer, preferably from a colorant basecoat and a final coat Clearcoat, show excellent resistance to impact, especially against stone chipping. Compared to commercially available fillers and demixed systems, a reduction in the proportion of the damaged surface and a very significant reduction in the proportion of the completely removed surface, that is to say the area fraction of the unprotected metal substrate, are observed in particular. In addition to these outstanding properties, the coatings produced with the coating compositions of the invention have excellent condensation resistance, excellent adhesion to the corrosion protection layer and the basecoat layer and excellent stability of the inherent color after curing. Furthermore, filler layers having a comparatively low stoving temperature and a good topcoat level can be achieved with the coating composition according to the invention.

The following examples are intended to illustrate the invention.

Examples

Preparation Example 1 Synthesis of the Aqueous Dispersion of a Polyester (Hydrophilic Component WP2) In a reactor with anchor stirrer, nitrogen inlet, reflux condenser and distillation bridge, 14,320 g of 1,6-hexanediol, 3.794 g of trimethylolpropane, 7.193 g of isophthalic acid, 4.570 g of adipic acid, 2.752 g phthalic acid and 0.669 g XyIoI submitted. The reaction mixture is overlaid with nitrogen and heated with stirring to 230 degrees C. The water of reaction is removed until the reaction mixture has an acid number according to DIN EN ISO 3682 of less than 4 mg KOH / g and a viscosity between 11 and 17 dPas (measured at 50 ° C. with a cone-plate viscometer from ICI ) having. Thereafter, the xylene is removed by distillation and the reaction mixture is cooled to 120 ° C. After this, 5.910 g of trimellitic anhydride are added, the reaction mixture is heated to 170 ° C. and the temperature is maintained until the reaction mixture has an acid number between 53 and 56 mg KOH / g and a viscosity between 390 and 630 mPas (measured at 120 ° C. with a Cone and plate viscometer from the company ICI). The resulting polyester has an acid number according to DIN EN ISO 3682 of 60 mg KOH / g and an OH number according to DIN EN ISO 4629 of 140. The reaction mixture is cooled to 120 ° C and 2.127 g of dimethylethanolamine are added. Thereafter, the reaction mixture is cooled to 95 degrees C. The polyester is taken up in 57.862 g of water, the pH is adjusted to 7.2 to 7.6 by adding more dimethyl ethanolamine. The resulting dispersion of the polyester has a solids content of 36% by weight.

Preparation Example 2: Synthesis of the aqueous dispersion of a polvurethane (hydrophobic component WPD

Synthesis of the polyester precursor:

30 g of 1, 6-hexanediol, 16 g of isophthalic acid, 54 g of dimer fatty acid (Pripol 1012 from Unichema) and 0.9 g of xylene are initially charged in a reactor with anchor stirrer, nitrogen inlet, reflux condenser and distillation bridge. The reaction mixture is overlaid with nitrogen and heated with stirring to 230 degrees C. The water of reaction is removed until the reaction mixture has an acid number according to DIN EN ISO 3682 of less than 4 mg KOH / g and a viscosity between 11 and 17 dPas (measured at 50 degrees C with a cone-plate viscometer from. ICI). Thereafter, the xylene is removed by distillation and the reaction mixture is cooled to 50 degrees C. The resulting polyester is taken up in 34.5 g of methyl ethyl ketone. The resulting dispersion of the polyester has a solids content of 36% by weight.

Synthesis of the Polyurethane Dispersion: In a reactor with anchor stirrer, nitrogen inlet and reflux condenser, 21, 386 g of the polyester precursor, 0.289 g of neopentyl glycol, 1.396 g of dimethylolpropionic acid, 7.529 g of methylene bis (4-isocyanatocyclohexane) and 2.502 g of methyl ethyl ketone are charged. The reaction mixture is blanketed with nitrogen and heated with stirring to 85 degrees C until a 1: 1 dilution of the reaction product with N-methylpyrrolidone an isocyanate content of 0.9 to 1, 2 wt .-% and a viscosity between 6 to 7 dPas (measured at 23 degrees C with a cone and plate viscometer from. ICI). Thereafter, 0.784 g of trimethylolpropane are added and the reaction mixture under nitrogen is heated with stirring to 85 ° C. until a 1: 1 dilution of the reaction product with N-methylpyrrolidone has an isocyanate content of less than 0.3% by weight and a viscosity between 12 to 13 dPas (measured at 23 degrees C with a cone-plate viscometer from. ICI). The resulting polyurethane has an acid number DIN EN ISO 3682 of 30 mg KOH / g and an OH number according to DIN EN ISO 4629 of 20.

The resulting polyurethane is taken up in 5.763 g of butyl glycol and 0.537 g of dimethylethanolamine are added. The polyurethane is taken up at a constant temperature of 80 degrees C in 50 g of water and then the methyl ethyl ketone is removed by distillation to a residual content of less than 0.4 wt .-%. The resulting dispersion of the polyurethane is applied to a pH adjusted to 7.2 to 7.4 by adding more dimethyl ethanolamine and water. The dispersion of the polyurethane has a solids content of 31% by weight.

Preparation Example 3 Synthesis of the Aqueous Dispersion of the Blocked Polvovan Coat (Hydrophilic Component WV)

In a reactor equipped with anchor stirrer, nitrogen inlet and reflux condenser, 26.032 g of trimerized hexamethylene diisocyanate (Desmodur 3300 from Bayer) and 8.5 g of N-methylpyrrolidone are charged. To the solution are added 7.891 g of methyl ethyl ketoxime. The reaction mixture is blanketed with nitrogen and kept under stirring at 70 degrees C until an NCO equivalent weight of 890 to 1060 Daltons is reached. After this, 6.077 g of dimethylpropionic acid are added and the reaction mixture is kept under nitrogen at 70.degree. C. with stirring until an NCO equivalent weight of more than 21,000 daltons is reached and a 1: 1 dilution of the reaction product with N-methylpyrrolidone has a viscosity between 4 , 2 to 5.2 dPas (measured at 23 degrees C with a cone-plate viscometer from. ICI). Thereafter, 1.5 g of butanol and 3.33 g of dimethylethanolamine are added and the temperature is maintained at 80 ° C. for 1 hour. The resulting blocked polyisocyanate is taken up in 44 g of water and the resulting dispersion of the blocked polyisocyanate is adjusted to a pH of 7.4 to 7.6 by adding further dimethylethanolamine and water. The dispersion of the blocked polyisocyanate has a solids content of 40 wt .-%.

Preparation Example 4 Synthesis of a Carbonation-Containing Mg / Al-Based Hydrotalcide Suspension An aqueous mixture of MgCl 2 .6H 2 O (1.64 molar) and AlCl 3 .6H 2 O (0.82 molar) is stirred at room temperature with constant stirring over 3 Hours to an aqueous solution of Na ₂ CO ₃ (0.16 molar), wherein the pH is kept constant by addition of 3M NaOH solution at pH = 9, wherein the metered amount of cations is chosen so that a molar ratio of Carbonate counterions to the trivalent Al cation of 1: 1 results. After addition of the aqueous mixture of the metal salts, the resulting suspension is aged at room temperature for 3 hours. The resulting precipitate is isolated by centrifugation and washed 4 times with deionized water. The resulting suspension of the white reaction product Mg2AI (OH) 6 (CO _{3) 0, 5} -2H2O (hydrotalcite suspension) has a solids content of 14.7 wt .-% and a pH value of 7.5.

PREPARATION EXAMPLE 5 Synthesis of a Zn / Al-based Hydrotalcite Suspension Containing Hydrogenation Aqueous mixture of ZnCl 2 .6H 2 O (1.23 molar) and AICl 3 .6H 2 O (0.61 molar) is stirred at room temperature with constant stirring over 3 Hours to an aqueous solution of Na ₂ CO ₃ (0.12 molar), wherein the pH is kept constant by addition of 3M NaOH solution at pH = 9, wherein the metered amount of cations is chosen such that a Molar ratio of the carbonate counterion to the trivalent Al cation of 1: 1 results. After addition of the aqueous mixture of the metal salts, the resulting suspension is aged at room temperature for 3 hours. The resulting precipitate is isolated by centrifugation and washed 4 times with deionized water. The resulting suspension of the white reaction product

Zn2AI (OH) δ (CO _{3) 0, 5} -2H2O (hydrotalcite suspension) has a solids content of 19.9 wt .-% and a pH value of 7.0.

Preparation Example 6 Synthesis of a Mg / Al-Based Hydrotalcite Suspension Modified with 3-Aminobenzenesulfonic Acid

A 0.21 molar aqueous solution of 3-aminobenzenesulfonic acid (3-absa) is an aqueous mixture of MgCl2-6H2O (0.52 molar) and AICI3 6H2O (0.26 molar) at room temperature under nitrogen atmosphere with constant stirring over 3 hours, wherein the metered amount of cations is chosen so that a molar ratio of the 3-para counterion to the trivalent Al cation of 4: 1 results. The pH is kept constant at pH = 10 by addition of a 3 molar NaOH solution.

After addition of the aqueous mixture of the metal salts, the resulting suspension is aged at room temperature for 3 hours. The resulting precipitate is isolated by centrifugation and washed 4 times with deionized water.

The resulting suspension of the white reaction product Mg 2 Al (OH) β (3-absa) 2H 2 O (hydrotalcite suspension) has a solids content of 28.6% by weight and a pH of 9.4.

Preparation Examples 7 to 10: Formulation of the Coating Compositions

In a first step, a dispersion of the mixture of coating agent components according to Preparation Examples 1 to 3 (amounts in Table 1 below) is prepared with stirring at room temperature. For this purpose, in the preparation examples 8 to 10, the hydrotalcite suspensions prepared according to Examples 4 to 6 (amounts in Table 1 below) are added with stirring at room temperature and stirring is continued for 12 hours until the hydrotalcite suspensions have completely dissolved (visual inspection). The resulting dispersion is treated with ultrasound for 15 minutes at room temperature while stirring, with the tip of an ultrasound source (Sonotrode UP 100H from Hielscher GmbH) being kept in the dispersion and the amplitude and pulse rate being set to 100% at an operating frequency of 30 kHz become. During the ultrasonic treatment, the temperature of the dispersion rises to 65 degrees C. The resulting dispersion is aged for 12 hours. In Comparative Example 7, a dispersion of the mixture of the coating agent components according to Preparation Examples 1 to 3 (amounts in Table 1 below) is prepared with stirring at room temperature and treated according to Examples 8 to 10 with ultrasound.

Thereafter, the dispersions are mixed with stirring at room temperature with melamine-formaldehyde resin (Maprenal MF 900 from Fa. Ineos Melamine GmbH) (quantities in Table 1 below).

Table 1: Composition of the coating compositions according to Preparation Examples 7 to 10

Examples 11 to 14: Production of OEM layer structures with coating compositions according to Preparation Examples 7 to 10 and testing of stone impact strength

The coating compositions according to the invention prepared according to Preparation Examples 7 (Comparison) and 8 to 10 are applied to pretreated and precoated with a cathodic dip paint steel panels (steel panels from. Chemetall: thickness of the baked cathodic dewax: 21 +/- 2 microns, thickness of the substrate : 750 μm) by means of spraying (automatic coater from Köhne). The resulting layers of the coating compositions are cured for 20 minutes at 140 degrees C, resulting in dry film thicknesses of 30 +/- 3 microns. For the production of an OEM layer structure, a commercially available aqueous basecoat material (FV95-9108 from BASF Coatings AG) is first applied to the boards precoated in this way, flashed off at 80 ° C. for 10 minutes, and finally a solvent-containing 2-component Clearcoat (FF95-0118 Fa. BASF Coatings AG) applied. The aqueous basecoat and the clearcoat are cured together for 20 minutes at 140 degrees C, after which the basecoat film has a dry film thickness of about 15 microns and the clearcoat film has a dry film thickness of 45 microns. The thus coated panels are stored for 3 days at 23 degrees C and 50% relative humidity.

The morphology of the filler layers in the OEM layer structure was investigated and characterized by optical microscopy (Table 2).

Rockfall test:

The coated steel panels prepared as described above are subjected to a rockfall test according to DIN 55996-1, wherein in each case 500 g of cooled iron granules (4 to 5 mm particle diameter, Fa. Würth, Bad Friedrichshall) are used and an air pressure of 2 bar at the bombardment (Model 508 VDA Fa. Erichsen) is set.

After cleaning the test panels thus damaged, they are immersed in a solution of an acidic copper salt, whereby elemental copper is deposited at the locations of the steel substrate at which the coating has been completely removed by the bombardment. The damage pattern on every 10 cm ^{2 of} the damaged and post-treated test panels are recorded by means of image processing software (SIS analysis). The fractions of the surfaces damaged by bombardment and the proportions of the completely removed surfaces, in each case based on the total surface, are evaluated. Table 2 shows the results. Table 2: Damage patterns of the Schichtaufbau- produced with the erfindunqsqäßen Beschich- Tunsmittel as well as with the reference filler

The hydrotalcites containing the more hydrophilic carbonation-containing coating compositions (Examples 12 and 13) have a bicontinuous phase structure or a structure stratified macroscopically after curing, whereas the coating compositions containing the hydrophobic organic counterion-modified hydrotalcites (Example 14) disperse after curing Has phase structure.

Compared with the layer structure (Example 11) produced with the comparative filler (Production Example 7), which also has a disperse phase morphology, the layer structures produced with the coating composition of the invention as filler material have a very significant reduction in the proportion of the completely removed surface, that is of the area fraction of the unprotected metal substrate. The adhesion to the cathodic dip coat and to the base coat layer is also excellent, which is reflected within the error limits of +/- 0.5 in an unchanged or reduced total damage of the surfaces.

The coating produced with the coating composition according to the invention moreover has an excellent condensation resistance and a virtually unchanged inherent color after firing.

Claims

claims:

1. Coating composition comprising at least one polymer (P1), at least one polymer (P2) which is incompatible with polymer (P1) in the solid phase and / or a crosslinking agent (V) which is incompatible with the polymer (P1) in the solid phase, the Polymers (P1) and / or (P2) have at least one functional group (a) which reacts on curing of the coating agent to form covalent bonds, characterized in that the coating agent contains 0.1 to 30% by weight, based on the non-volatile constituents of the coating agent, electrically charged inorganic particles (AT) whose mean particle diameter (D) is <1 / vm and whose average ratio D / d of the average particle diameter (D) to the average particle thickness (d) is> 50, contains.

2. Coating composition according to claim 1, characterized in that the crosslinking agent (V) contains at least two functional groups (b) which react with the functional group (a) to form covalent bonds.

3. Coating composition according to one of claims 1 or 2, characterized in that it comprises an aqueous phase and the polymer (P1) is water-dispersible and / or the polymer (P2) is water-dispersible and / or the crosslinking agent (V) is water-dispersible ,

4. Coating composition according to one of claims 1 to 3, characterized the amount of the difference [δ (P1) -δ (P2) and / or δ (V)] of the solubility parameters according to Hildebrand δ (P1) of the polymer (P1) and δ (P2) of the polymer (P2) and / or δ (V) of the crosslinking agent (V) is at least 1.

5. Coating composition according to one of claims 1 to 4, characterized in that the electrically charged inorganic particles (AT) prior to incorporation into the coating agent in aqueous suspension.

6. Coating composition according to one of claims 1 to 5, characterized in that the electrically charged inorganic particles (AT) are positively charged.

7. Coating composition according to claim 6, characterized in that the electrically charged inorganic particles (AT) to at least one mixed hydroxide of the general formula

(M _{(1 x) 2} ⁺ M _{x 3} ⁺ (OH) ₂ ) (A _{x / y} ^y -) - nH ₂ O

where M ^{2+ are} divalent cations, M ^{3+ are} trivalent cations and (A) are anions of valency y, and optionally at least part of the anions (A) is replaced by singly charged organic anions (OA).

8. Coating composition according to claim 7, characterized in that M ²⁺ zinc and / or magnesium ions are selected as divalent cations and / or are selected as trivalent cations M 3 ⁺ aluminum ions and / or as anions (A) phosphate ions, sulfate ions and / or carbonations are used.

9. A process for the production of impact resistant OEM composite layers, consisting of a directly applied to the substrate corrosion protection layer, a filler layer, a basecoat layer and a final clearcoat layer, characterized in that at least one layer of the coating agent measure GE any one of claims 1 to 8 formed becomes.

10. The method according to claim 9, characterized in that the filler layer is formed from the coating composition according to one of claims 1 to 8.