DE19958726A1 - Production of colored and-or decorative effect multi layer coatings, e.g. for painting cars, involves overcoating basecoat with clearcoat comprising special dual-cure aqueous polyurethane dispersion - Google Patents

Abstract

The invention relates to a method for producing a coloured and/or decorative-effect multi-layered coating on a primed or unprimed substrate. According to said method, a base lacquer layer and a clear lacquer layer are applied one on top of another, the clear lacquer containing an aqueous, blocked isocyanate group which in turn consists of or contains a polyurethane dispersion. The polyurethane consists of aliphatic polyisocyanates, compounds containing functional groups reactive to isocyanate and bonds which can be activated by actinic radiation, low-molecular aliphatic compounds containing functional groups reactive to isocyanate and dispersing functional groups, in addition to neutralising agents for said dispersing functional groups. The blocked isocyanate groups are introduced into the polyurethane dispersion by adding blocked polyisocyanates and/or by reacting blocking agents for isocyanate groups and/or compounds containing blocked isocyanate groups with the polyurethane prepolymers containing isocyanate groups. The aqueous clear lacquer can be a powder slurry.

Description

The present invention relates to a novel process for producing a color and / or effect multicoat paint on a primed or unprimed Substrate. Furthermore, the present invention relates to a new powder slurry.

Automotive OEM and refinish coatings are used by automakers and their customers have growing demands for corrosion resistance, the mechanical stability, such as scratch resistance to washing brushes, the Stone chip resistance and the overall visual impression, including the optical effects, posed. As is known, this is to some extent due to a multi-layered Paint done on a body sheet an electro-dip, a Füllerlackierung or Steinschlagschutzgrundierung and a color and / or effect-giving multi-layer coating of a color and / or effect Basecoat and at least one clearcoat is superimposed.

In addition, but the paint finishes are also still in recent years steadily Increased environmental requirements, such as the reduction of organic content Solvents or complete solvent-free, meet.

In the course of these developments, aqueous paints have gradually become established. Thus, the electrocoating paints have long been almost free of volatiles organic ingredients, especially organic solvents. Likewise, aqueous Coating materials based on polyurethanes available to manufacture of surfacer coats or antistonechip primers (cf. Patent Specifications DE-A-40 05 961 and EP-A-0 548 873).

The use of water-based paints, as described for example in the patent DE-C-197 22 862 has brought significant progress and permanently reduces the emissions of volatile organic compounds.

Meanwhile, solvent-free or largely solvent-free clearcoats such as Aqueous two-component (2K) or multi-component (3K, 4K) clearcoat materials,  Powder clearcoats, powder slurry clearcoats or liquid, solvent-free, with actinic Radiation curable clearcoats (100% systems) are available.

Actinic radiation can be electromagnetic radiation such as visible light, UV light or X-rays or corpuscular radiation like Act electron radiation.

Waterborne two-component (2K) or multi-component (3K, 4K) clearcoat materials For example, from the German patent DE-A-44 21 823. Two component (2K) or multi-component (3K, 4K) clearcoat materials included known as the essential ingredients hydroxyl-containing binder and Polyisocyanates as crosslinking agents, which are stored separately until their use Need to become.

Powder clearcoats are known for example from German Patent DE-A-42 22 194 or the product information of BASF Lacke + Farben AG, "powder coatings", 1990 known. Powder clearcoats are known to be essential constituents epoxide group-containing binders and polycarboxylic acids as crosslinking agents.

Powder slurry clearcoats are described, for example, in US Pat. No. 4,268,542 international patent application WO 96/32452 and the German patent applications DE-A-195 18 392.4 and DE-A-196 13 547 are known or are not in the German patent application DE-A-198 14 471.7. Powder slurry clearcoats are known to contain powder clearcoats in an aqueous Medium dispersed.

Clearcoats curable with actinic radiation are known, for example, from the patents EP-A-0 540 884, EP-A-0 568 967 or US-A-4,675,234. They contain known to be curable with actinic light and / or electron radiation low molecular weight, oligomeric and / or polymeric compounds, preferably rad lenhärtbare binders, in particular based on ethylenically unsaturated prepolymer and / or ethylenically unsaturated oligomers, optionally one or more reac tivverdünner and optionally one or more photoinitiators. Examples suitable radiation-curable binders are (meth) acrylic functional  (Meth) acrylic copolymers, polyether acrylates, polyester acrylates, unsaturated polyesters, Epoxy acrylates, urethane acrylates, amino acrylates, melamine acrylates, silicone acrylates and the corresponding methacrylates. Binders are preferably used which are free from are aromatic structural units.

From the European patent application EP-A-0 928 800 is a thermally and with actinic radiation curable dual cure coating material known in the art Urethane (meth) acrylate having free isocyanate groups and (meth) acryloyl groups, a Photoinitiator and an isocyanate-reactive compound, in particular a polyol or Polyamine, contains. This dual cure coating offers the opportunity to use the Property profiles of coating material and coating to vary and targeted to adapt to different uses.

The disadvantage of the known dual-cure coating materials is that it is so-called two-component systems, in which the components, the free Isocyanate groups until application in the absence of water or separately from the constituents containing the isocyanate-reactive groups must be in order to avoid premature networking. But this requires one higher technical and planning effort in storage, production and the Application.

Preferably, the known water-based paints and clearcoats in the context of Production of color and / or effect multicoat paint systems according to the Processed so-called wet-in-wet process. As is known, in the case of the wet-in- wet-process a basecoat applied to a primed or ungrounded substrate, after which the resulting basecoat film is dried, overcoated with a clearcoat and the resulting clearcoat layer co-cures with the basecoat layer, thereby the multi-layer coating of color and / or effect basecoat and protective clearcoat results.

In the wet-on-wet process, the individual clearcoat types have specific strengths and weaknesses.  

Thus, the aqueous clearcoats on or after their application, a breach in the show dried aqueous basecoat. Powder clearcoats can not do one have sufficient course during curing, resulting in structured surfaces leads.

After curing, clearcoats based on two-component (2K) - or Although multi-component (3K, 4K) clearcoats are weather-stable, they are often not sufficiently resistant to abrasion. With actinic radiation curable clearcoats have in their Curing often has a strong shrinkage, resulting in internal delamination Tension leads. Moreover, they can be more complex shaped after their application Substrates in the shadow areas are cured only insufficient. powder slurry Clearcoats are more or less compatible with some commonly used waterborne basecoats incompatible, causing cracking (mud cracking) in the multi-layer coating and Delamination of the layers may result.

From the German patent application DE-A-196 45 761 are hydrophilic self-crosslinking Polyurethanes are known which blocked olefinically unsaturated groups and terminal ones Contain isocyanate groups. The blocking agents, however, are not closer specified. These known hydrophilic self-crosslinking polyurethanes are used for Preparation of graft copolymers according to the emulsion polymerization method used. The resulting dispersions of the graft copolymers become Production of water-based paints and not used by clearcoats. The production Color and / or effect multi-layer coatings according to the wet-on-wet process, in which basecoat films are overcoated with clearcoat films, followed by cures both layers together, is not addressed in the patent application. Nor does the combination of thermal curing and curing with actinic Radiation (dual cure) described in the patent application.

From the German patent DE-C-197 22 862 is a Fremdvernetzendes Graft copolymer obtainable by dissolving in a dispersion of a olefinically unsaturated, hydrophilic functional groups having polyurethane on a statistical average from 0.05 to 1.1 polymerizable pendent and / or terminal double bonds per molecule of olefinically unsaturated monomers polymerized. The known externally crosslinking graft copolymers of DE-C-197 22 862  are present as primary dispersions and are very good for the production of aqueous Externally crosslinking coating materials, in particular water-based paints, suitable. When Crosslinking agents may contain blocked isocyanates. The externally networked Water-based paints can be advantageous for the production of color and / or effect Multi-layer coatings can be used by the wet-in-wet process. The patent does not describe the use of the primary dispersions for the preparation of Clearcoats that can be cured thermally and with actinic radiation.

In the context of the present invention, the term "self-crosslinking" denotes the Property of a binder (for the term see Rompp Lexikon Lacke and Printing inks, Georg Thieme-Verlag, Stuttgart, New York, 1998, "Binders", p. 73 and 74) to engage in self-crosslinking reactions. The prerequisite for this is that in the binders already both types of complementary reactive functional Contain groups that are necessary for networking. As externally crosslinking On the other hand, such coating materials are referred to, wherein one type of complementary reactive functional groups in the binder, and the other kind in a hardener or crosslinking agent. In addition, this is on Römpp Lexikon Lacke und Druckfarben, Georg Thieme-Verlag, Stuttgart, New York, 1998, "Hardening", pages 274 to 276, especially page 275, below.

In the non-prepublished German patent application entitled "With UV Radiation and thermally curable aqueous polyurethane dispersions and their Use "(internal file number of BASF Aktiengesellschaft: O. Z. 0050/50768, filed on 05.10.1999) becomes a thermally curable and with actinic radiation Clearcoat based on an aqueous polyurethane dispersion described Hydroxyl groups, blocked isocyanate groups and olefinically unsaturated groups and dispersing ionic groups. The use of these clearcoats in The wet-in-wet process is not described herein.

Non-prepublished German patent application DE-A-199 08 013.5 describes a structurally viscous, with actinic radiation and optionally thermally curable powder slurry containing solid spherical particles having an average particle size of 0.8 to 20 microns and a maximum particle size of 30 microns, wherein the powder clearcoat slurry has a content of ion-forming dispersing groups of 0.05 to 1 meq / g, corresponding to an average acid number or amine number of 3 to 56 g KOH / g solids (MEQ acid or amine of 0.05 to 1.0 meq / g of solids), preferably to 28 (MEQ acid or amine: 0.5) and especially to 17 (MEQ acid or amine: 0.3), a neutralizing agent content of 0.05 to 1 meq / g and a viscosity of (i) 50 to 1000 mPa.s at a shear rate of 1000 s ^-1 , (ii) 150 to 8000 mPa.s at a shear rate of 10 s ^-1 and (iii) 180 to 12000 mPa.s at a shear rate of 1 s ^-1 . In addition, the powder clearcoat slurry may contain binders with reactive functional groups such as hydroxyl groups, which may undergo thermal crosslinking reactions with crosslinking agents such as blocked isocyanates. Thus, here the blocked isocyanate groups are introduced by adding a separate compound having at least one blocked isocyanate group in the powder clearcoat slurry.

In the not previously published German patent application DE-A-199 08 018.6 is a Dual Cure Powder Clearcoat Slurry that contains ingredients that work with both actinic radiation activatable groups (A) as well as complementary reactive functional groups (B) that undergo thermal crosslinking reactions such as Hydroxyl groups / blocked isocyanate groups or carboxyl groups / epoxide groups, contain. However, the content of acid groups in these components is not closer specified. In addition, they do not primarily serve to disperse the ingredients, but their networking.

There is therefore still a need for a process for producing color and / or effect multicoat paint systems, the disadvantages of the prior Technology no longer has, but safe and reliable Which provides color, effect, gloss and D.O.I. (distinctiveness of the reflected image), of the highest optical quality, a smooth, structure-free, hard, flexible and scratch-resistant surface have weather-, chemical- and etch-resistant, not yellowing and no cracking and delamination of the Show layers.

The object of the present invention is to meet this need.

Accordingly, the novel process for producing a multicoat color and / or effect coating on a primed or unprimed substrate has been found in which a basecoat film and at least one clearcoat film are applied to one another, at least one of the clearcoat materials comprising at least one aqueous polyurethane dispersion having an acid number of 5.0 contains or consists of 100 mg KOH / g

• A) at least one aliphatic polyisocyanate having an isocyanate functionality of 2.0 to 6.0,
• B) at least one compound having at least one isocyanate-reactive functional group and at least one with actinic radiation activatable bond,
• C) at least one low molecular weight aliphatic compound having at least two isocyanate-reactive functional groups,
• D) at least one compound having at least one isocyanate-reactive functional group and at least one dispersing functional group,
• E) at least one neutralizing agent for the dispersing functional Groups of compound D),
• F) at least one blocking agent for isocyanate groups and / or at least a compound having at least one blocked isocyanate group as well possibly
• G) at least one compound other than compounds B) to F) an isocyanate-reactive functional group

is constructed, wherein the blocked isocyanate groups on the implementation of Blocking agent F) with the polyurethane prepolymers containing isocyanate groups, the from the reaction of a stoichiometric excess of the compounds A) with the Compounds B) and optionally C) and with a dispersibility in aqueous media sufficient amount of compounds D) and E) result in the Polyurethane dispersion are introduced.  

In the following, the new method for producing a color and / or effect multicoat paint on a primed or unprimed substrate for the sake of brevity referred to as "inventive method".

Other inventive objects will be apparent from the description.

In view of the prior art, it was surprising and not for the expert Foreseeable that the object on which the present invention was based, with the aid of inventive method could be solved. In particular, it was surprising that the inventive method color and / or effect Provides multi-layer coatings, even on complex shaped substrates completely cured, highly scratch resistant and resistant to chemicals. Particularly noteworthy is that by means of the method according to the invention multi-layer coatings, the optionally also comprise primers, based solely on aqueous Lacquers can be produced.

The inventive method is used to produce color and / or effect Multilayer coatings on primed or unprimed substrates.

The substrates are all surfaces to be painted, which by curing the coatings applied thereto are not damaged by the application of heat, into consideration; these are z. B. metals, plastics, wood, ceramics, stone, textile, Fiber composites, leather, glass, glass fibers, glass and rock wool, mineral and Resin-bound building materials, such as gypsum and cement boards or roof tiles, as well as composites of these materials. Accordingly, the inventive method is also for applications suitable outside the automotive paint shop. This is particularly true for the Painting of furniture and industrial painting, including coil coating, containers Coating and impregnation or coating of electrotechnical components, in Consideration. In the context of industrial coatings, it is suitable for painting virtually all parts for private or industrial use such as radiators, Household appliances, small metal parts such as nuts and bolts, hubcaps, rims, Emballagen or electrical engineering components such as motor windings or Transformer windings.  

In the case of electrically conductive substrates primers may be used which are in customary and known manner of electrocoating (ETL) are produced. Therefor come both anodic (ATL) and cathodic (KTL) electrodeposition paints, but especially KTL, into consideration. In the case of metal, the substrate may also be one Surface treatment, such as galvanization or phosphating or anodization.

In particular, in automotive OEM finishing is on the fully cured or the merely dried electrocoating (ETL) a filler or a Rockfall protection primer applied. This paint layer is either on its own or completely with the underlying electrodeposition paint layer hardened. The applied surfacer coat can also be merely dried or partially after which they are cured with the overlying varnish layers as well optionally completely cured with the underlying electrodeposition coating becomes (extended wet-in-wet method). Within the scope of the present invention the term primer also the combination of electrocoating and Surfacer or antistonechip primer.

The process according to the invention may also include primed or unprimed Plastics such. ABS, AMMA, ASA, CA, CAB, EP, UF, CF, MF, MPF, PF, PAN, PA, PE, HDPE, LDPE, LLDPE, UHMWPE, PET, PMMA, PP, PS, SB, PUR, PVC, RF, SAN, PBT, PPE, POM, PUR-RIM, SMC, BMC, PP-EPDM and UP (abbreviations according to DIN 7728T1). The plastics to be painted can Of course, polymer blends, modified plastics or fiber-reinforced Be plastics. It can also usually in vehicle construction, in particular Automotive, used plastics are used.

In the case of non-functionalized and / or non-polar substrate surfaces, these can before coating in a known manner a pretreatment, such as with a plasma or by flaming, subjecting or hydro priming.

According to the invention, in a first process step, a thermal and optionally with actinic radiation curable pigmented basecoat, in particular  a water-based paint, applied to the primed or ungrounded substrate, whereby the Basecoat layer results.

Examples of suitable aqueous basecoats are known from the patents EP-A-0 089 497, EP-A-0 256 540, EP-A-0 260 447, EP-A-0 297 576, WO 96/12747, EP-A-0 523 610, EP-A-0 228 003, EP-A-0 397 806, EP-A-0 574 417, EP-A-0 531 510, EP-A-0 581 211, EP-A-0 708 788, EP-A-0 593 454, DE-A-43 28 092, EP-A-0 299 148, EP-A-0 394 737, EP-A-0 590 484, EP-A-0 234 362, EP-A-0 234 361, EP-A-0 543 817; WO 95/14721, EP-A-0 521 928, EP-A-0 522 420, EP-A-0 522 419, EP-A-0 649 865, EP-A-0 536 712, EP-A-0 596 460, EP-A-0 596 461, EP-A-0 584 818, EP-A-0 669 356, EP-A-0 634 431, EP-A-0 678 536, EP-A-0 354 261, EP-A-0 424 705, WO 97/49745, WO 97/49747 or US Pat EP-A-0 401 565.

The application of the waterborne basecoat can be achieved by all common application methods, such as As spraying, knife coating, brushing, pouring, dipping, watering, trickling or rolling respectively. In this case, the substrate to be coated can rest as such, wherein the Application device or system is moved. However, even the one to be coated Substrate, in particular a coil to be moved, wherein the application system relative to Substrate is resting or moved in a suitable manner.

Preferably, spray application methods are used, such as Compressed air spraying, airless spraying, high rotation, electrostatic spray application (ESTA), optionally combined with hot spray application such as hot air Hot spraying. The application can be carried out at temperatures of max. 70 to 80 ° C performed be so that suitable application viscosities are achieved without that in the short term acting thermal stress a change or damage of the Waterborne paints and his possibly reprocessed overspray occur. Thus, the hot spraying can be designed so that the water-based paint only very briefly in the or just before the spray nozzle is heated.

The spray booth used for the application, for example, with a optionally circulating, which can be operated with a suitable Absorption medium for the overspray, z. B. the water-based paint itself, is operated.  

The application is preferably when illuminated with visible light of a wavelength of over 550 microns or in the absence of light when the water-based paint thermally curable and with actinic radiation. This will be a material Change or damage to the water-based paint and overspray avoided.

Of course, the application methods described above can also in the production of the other paint layers in the context of the method according to the invention be applied.

In the context of the process according to the invention, the waterborne basecoat layer is after their application cured thermally or thermally and with actinic radiation. Because of their high content of pigments, which strongly absorb the actinic radiation and / or sprinkle, the aqueous basecoat film is preferably thermally cured. In this case, the methods of the thermal methods described below are preferred Curing and optionally the methods of curing described below actinic radiation applied.

In the context of the process according to the invention, the thermal curing can be immediate take place after application of the aqueous basecoat. Optionally, this can the underlying, not yet fully cured lacquer layers of Primer to be cured with. According to the invention it is advantageous if the Primer is already fully cured before applying the water-based paint.

In the context of the process according to the invention, the aqueous basecoat film is used preferably not cured, but only dried or partially cured. That is, that none of the existing functional groups capable of thermal crosslinking be converted or only a part thereof, for example up to 90, preferably up to 80 and in particular up to 70 mol%, is reacted.

In the method according to the invention, the aqueous basecoat film or the Waterborne coating, in particular the aqueous basecoat film, with a Clearcoat I from a clearcoat thermally curable with actinic radiation I. overlayed. It is essential for the process according to the invention that it is possible to use as clearcoat I uses a clearcoat to be used according to the invention, which comprises an aqueous  Contains or consists of polyurethane dispersion, which from the below described Starting products A), B), C), D), E) and F) and optionally G) is constructed.

In general, the basecoat film and clearcoat film will be in a wet film thickness applied, that after their curing layers with the necessary for their functions and advantageous layer thicknesses result. In the case of the base coat it is 5 to 50, preferably 5 to 40, more preferably 5 to 30 and in particular 10 to 25 μm, and in the case of clearcoats, it is 10 to 100, preferably 15 to 80, particularly preferably 20 to 75 and in particular 25 to 70 microns.

In a first variant of the method according to the invention, the clearcoat film I for cured alone. This assumes that the underlying layers of paint already completely cured.

In a second, preferred variant of the method according to the invention is the Clearcoat I I cured together with the basecoat.

Curing can take place after a certain rest period. It can last for 30 seconds to 2 h, preferably 1 min to 1 h and especially 1 min to 45 min. The Rest period serves, for example, for the course and degassing of the clearcoat film I and to evaporate volatiles such as water and possibly still existing solvents. The rest period can be increased by the application of elevated temperatures to 90 ° C and / or by a reduced air humidity <10 g of water / kg of air, in particular < 5g / kg of air, supported and / or shortened, provided that no damage or damage occurs Changes in the paint layers occur, such as premature complete networking.

In a first preferred variant, the curing of the clearcoat film I takes place alone with actinic radiation, resulting in advantageous technical effects, if this no photoinitiators are used in clearcoat I. Preferably, this is Variant the waterborne basecoat already completely or at least partially hardened.

In a second preferred variant, the curing of the clearcoat film I takes place thermally and with actinic radiation, wherein no photoinitiator needs to be present.  

Preferably, in this variant, the aqueous basecoat is not or only partially hardened.

In a further variant, the curing of the clearcoat film I alone takes place thermally, wherein initiators of free-radical polymerization are used in clearcoat I can. Preferably, in this variant, the aqueous basecoat is not or only partially cured.

Preferably, the curing is carried out with actinic radiation with UV radiation and / or electron beams. Preferably, a dose of from 1,000 to 2,000, preferably from 1,100 to 1,900, particularly preferably from 1,200 to 1,800, very particularly preferably from 1,300 to 1,700 and in particular from 1,400 to 1,600 mJ / cm ^{2 is} used. Optionally, this cure can be supplemented with actinic radiation from other sources. In the case of electron beams, it is preferable to operate under an inert gas atmosphere. This can be ensured, for example, by supplying carbon dioxide and / or nitrogen directly to the surface of the clearcoat film I. Even in the case of curing with UV radiation, to avoid the formation of ozone, under inert gas can be used.

For curing with actinic radiation, the usual and known Radiation sources and optical aids applied. Examples of suitable Radiation sources are flash lamps of the company VISIT, mercury high or low-pressure vapor lamps, which are optionally doped with lead to a Beam windows open up to 405 nm, or electron beam sources. Their arrangement is known in principle and can the conditions of the workpiece and the Process parameters are adjusted. For complicated shaped workpieces like them are intended for automotive bodies, the non-direct radiation accessible areas (shadows) such as cavities, folds and others Design-related undercuts with point, small area or Rundumstrahlern associated with an automatic movement device for the Irradiation of cavities or edges (partially) cured.  

The systems and conditions of these curing methods are described, for example, in R. Holmes, U.V. and E.B. Curing Formulations for Printing Inks, Coatings and Paints, SITA Technology, Academic Press, London, United Kingdom 1984.

Here, the curing can be done in stages, d. H. through multiple exposure or Irradiation with actinic radiation. This can also be done alternately, d. h., that is cured alternately with UV radiation and electron radiation.

The thermal curing has no special features, but takes place by the usual and known methods such as heating in a convection oven or Irradiate with IR lamps. As in the case of curing with actinic radiation, the thermal hardening gradually. Advantageously, the thermal Curing at temperatures above 100 ° C. In general, it is recommended here Temperatures of 180 ° C, preferably 170 ° C and especially 150 ° C not to exceed.

Are the thermal curing and curing together with actinic radiation applied, these methods can be used simultaneously or alternately. If the two curing methods used alternately, for example, with the thermal curing started and ended with curing with actinic radiation become. In other cases, it may prove advantageous to cure with Actinic radiation to begin and end hereby. Special benefits result when the clearcoat I in two separate steps first with actinic Radiation and then thermally cured.

Of course, the curing methods described above in the context the method according to the invention also for curing the other lacquer layers be applied.

The by the above-described embodiment of the invention Method resulting color and / or effect multi-layer coating can still with a layer of organically modified ceramic material, like it For example, under the brand Ormocer® commercially available coated.  

In an alternative embodiment of the method according to the invention, a clearcoat film I of a thermally and / or actinic radiation-curable clearcoat I is applied to the surface of the basecoat film, in particular aqueous basecoat film, and

• - partially by itself,
• Partially, together with the basecoat,
• - together with the basecoat layer completely or
• - completely by itself

cured thermally and / or with actinic radiation, the above in detail described methods are used.

Subsequently, on the surface of the clearcoat film I or the clearcoat I, a further clearcoat film II is applied from a clearcoat II curable thermally and / or with actinic radiation, after which

• - the Karlack layer II alone or
• - together with the underlying not yet fully cured paint layers

thermally and / or fully cured with actinic radiation, the above described methods are used.

For the further alternative of the method according to the invention, it is essential that at least one of the clearcoats I or II a clearcoat to be used according to the invention is that contains or consists of an aqueous polyurethane dispersion, which consists of the starting materials A), B), C), D), E) and F) described below optionally G) and thus curable thermally and with actinic radiation. The other clearcoat may then be one of the customary and known ones described above Clearcoats or a common and well-known one-component (1K) clearcoat, as he For example, in the patents DE-A-42 04 518, US-A-5,474,811, US-A-5,356,669, US-A-5,605,965, WO 94/10211, WO 94/10212, WO 94/10213, EP-A-0 594 068, EP-A-0 594 071 or EP-A-0 594 142. This one-component (1K) -  Clearcoats contain, as is known, hydroxyl-containing binders and Crosslinking agents such as blocked polyisocyanates, tris (alkoxycarbonylamino) triazines and / or aminoplast resins. In another variant they contain as binders Polymers with pendant carbamate and / or allophanate groups and optionally carbamate- and / or allophanate-modified aminoplast resins as crosslinking agents.

For the inventive method and the resulting color and / or It is advantageous if multicoat paint systems are effective if the clearcoat is II is a clearcoat to be used according to the invention.

Also in this embodiment of the method according to the invention can resulting color and / or effect multi-layer coating still with a layer from an organically modified ceramic material such as, for example, under the trademark Ormocer® is commercially available coated.

The thermal and actinic process to be used for the process according to the invention Radiation curable clearcoat contains an aqueous polyurethane dispersion or consists of this. In the aqueous polyurethane dispersion can be activated with actinic radiation Bonds, isocyanate-reactive functional groups, blocked isocyanate groups and containing dispersing functional groups as essential functional groups. The The aqueous polyurethane dispersion to be used according to the invention is therefore in the beginning Self-crosslinking.

In the context of the present invention is under a with actinic radiation activable bond understood a bond that upon irradiation with actinic Radiation becomes reactive and with other activated bonds of its kind Polymerization reactions and / or crosslinking reactions, which after radical and / or ionic mechanisms. Examples of suitable bonds are carbon-hydrogen single bonds or carbon-carbon, Carbon-oxygen, carbon-nitrogen, carbon-phosphorus or Carbon-silicon single bonds or double bonds. Of these, the Carbon-carbon double bonds are particularly advantageous and therefore very particularly preferably used according to the invention. For the sake of brevity they will be in hereinafter referred to as "double bonds".  

Particularly suitable double bonds are, for example, in (meth) acrylate, Ethacrylate, crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl, Norbornenyl, isoprenyl, isopropenyl, allyl or butenyl groups; dicyclopentadienyl, Norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ether groups or Dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or Butenylestergruppen included. Of these, the acrylate groups offer very special Advantages, why they are very particularly preferably used according to the invention.

Examples of suitable isocyanate-reactive functional groups are thio, hydroxyl, Amino and / or imino groups, in particular thio, hydroxyl and / or amino groups.

Preferably, the isocyanate groups are blocked with the blocking agents F) known from US-A-4,444,954. Examples of suitable blocking agents F) are

• a) phenols such as phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, tert-butylphenol, hydroxybenzoic acid, esters of this acid or 2,5-di-tert.-butyl 4-hydroxytoluene;
• b) lactams, such as ε-caprolactam, δ-valerolactam, γ-butyrolactam or β- propiolactam;
• c) active methylenic compounds, such as diethyl malonate, dimethyl malonate, Acetoacetic acid ethyl or methyl ester or acetylacetone;
• d) alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, n-amyl alcohol, t-amyl alcohol, lauryl alcohol, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, Diethylene glycol monoethyl ether, propylene glycol monomethyl ether, Methoxymethanol, Glycolic acid, Glycolic acid esters, Lactic acid, Lactic acid esters, Methylolurea, methylolmelamine, diacetone alcohol, ethylene chlorohydrin,  Ethylene bromohydrin, 1,3-dichloro-2-propanol, 1,4-cyclohexyldimethanol or acetone cyanohydrin;
• e) mercaptans such as butylmercaptan, hexylmercaptan, t-butylmercaptan, t-butyl dodecyl; 2-mercaptobenzothiazole, thiophenol, methylthiophenol or ethylthiophenol;
• f) acid amides such as acetoanilide, acetoanisidine amide, acrylamide, methacrylamide, Acetic acid amide, stearic acid amide or benzamide;
• g) imides such as succinimide, phthalimide or maleimide;
• h) amines such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, Carbazole, aniline, naphthylamine, butylamine, dibutylamine or butylphenylamine;
• i) imidazoles such as imidazole or 2-ethylimidazole;
• j) ureas such as urea, thiourea, ethyleneurea, ethylene thiourea or 1,3-diphenylurea;
• k) carbamates such as N-phenylcarbamic acid phenyl ester or 2-oxazolidone;
• l) imines such as ethyleneimine;
• m) oximes such as acetone oxime; Formaldoxime, acetaldoxime, acetoxime, Methyl ethyl ketoxime, diisobutyl ketoxime, diacetyl monoxime, benzophenone oxime or chlorohexanone oximes;
• n) salts of sulfurous acid such as sodium bisulfite or potassium bisulfite;
• o) hydroxamic acid esters such as benzylmethacrylohydroxamate (BMH) or allyl methacrylohydroxamate; or
• p) substituted pyrazoles, in particular dimethylpyrazole or triazoles; such as  
• q) mixtures of these blocking agents, in particular dimethylpyrazole and triazoles, Malonic esters and acetoacetic esters or dimethylpyrazole and succinimide.

Examples of suitable dispersing functional groups are (potentially) anionic Groups such as carboxylic acid, sulfonic acid or phosphonic acid groups, in particular Carboxylic acid groups. They are to be used in the invention Polyurethane dispersion present in an amount such that an acid number of 5.0 to 100, preferably 6.0 to 90, preferably 7.0 to 80, particularly preferably 8.0 to 70, completely particularly preferably 9.0 to 60 and in particular 10 to 50 mg KOH / g results.

For the process according to the invention it is essential that the polyurethane dispersion so from the starting products A) to F) described below and, if appropriate, G) is prepared that the essential functional groups described above in a component, i. H. the polyurethane.

The polyurethane to be used according to the invention therefore preferably contains on a statistical average

• - At least one, preferably at least two and in particular at least three of above-described activatable with actinic radiation bonds,
• - At least one, preferably at least two and in particular at least three of Blocked isocyanate groups described above and
• - At least one, preferably at least two and in particular at least three of Isocyanate-reactive functional groups described above.

The polyurethane is in the polyurethane dispersions to be used according to the invention preferably in an amount of, based on the dispersion, 5 to 80, preferably 10 to 70, more preferably 15 to 60, most preferably 20 to 50 and in particular 25 to 40 wt .-% included.  

The aqueous polyurethane dispersion or the polyurethane contained therein is constructed from at least one aliphatic, including cycloaliphatic polyisocyanate A) with an isocyanate functionality of 2.0 to 6.0, preferably 2.0 to 5.0, preferably 2.0 to 4.5 and especially 2.0 to 3.5. In the context of the present invention the term "cycloaliphatic diisocyanate" means a diisocyanate wherein at least one Isocyanate group is bonded to a cycloaliphatic radical.

Examples of suitable cycloaliphatic polyisocyanates A) having an isocyanate functionality of 2.0 are isophorone diisocyanate (= 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethyl- cyclohexane), 5-isocyanato-1- (2-isocyanatoeth-1-yl) -1,3,3-trimethylcyclohexane, 5- Isocyanato-1- (3-isocyanatoprop-1-yl) -1,3,3-trimethylcyclohexane, 5-isocyanato (4- isocyanatobut-1-yl) -1,3,3-trimethylcyclohexane, 1-isocyanato-2- (3-isocyanatoprop-1-yl) - cyclohexane, 1-isocyanato-2- (3-isocyanatoeth-1-yl) cyclohexane, 1-isocyanato-2- (4- isocyanatobut-1-yl) cyclohexane, 1,2-diisocyanatocyclobutane, 1,3- Diisocyanatocyclobutane, 1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2- Diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane Dicyclohexylmethane-2,4'-diisocyanate or dicyclohexylmethane-4,4'-diisocyanate, in particular isophorone diisocyanate.

Examples of suitable, acyclic aliphatic to be used according to the invention Diisocyanates are trimethylene diisocyanate, tetramethylene diisocyanate, pentame thylene diisocyanate, hexamethylene diisocyanate, ethylethylene diisocyanate, trimethylhexane diisocyanate, heptanemethylene diisocyanate or diisocyanates derived from Dimer fatty acids, such as those sold under the trade name DDI 1410 by Henkel sold and described in the patents DO 97/49745 and WO 97/49747 in particular 2-heptyl-3,4-bis (9-isocyanatononyl) -1-pentyl-cyclohexane, or 1,2-, 1,4- or 1,3-bis (isocyanatomethyl) cyclohexane, 1,2-, 1,4- or 1,3-bis (2-isocyanatoeth-1) yl) cyclohexane, 1,3-bis (3-isocyanatoprop-1-yl) cyclohexane or 1,2-, 1,4- or 1,3-bis (4- isocyanatobut-1-yl) cyclohexane.

Of these, hexamethylene diisocyanate is of particular advantage and therefore becomes very particularly preferably used according to the invention.  

Examples of suitable polyisocyanates A) having an isocyanate functionality <2 are Polyisocyanates, in particular based on hexamethylene diisocyanate, the isocyanurate Biurethane, allophanate, iminooxadiazinedione, urethane, urea, carbodiimide and / or Have urethione groups and in the usual and known manner from the above Diisocyanates described are available. Of these, the allophanate groups are advantageous and are therefore particularly preferably used according to the invention.

Examples of suitable compounds B) having at least one, in particular one, functional group and at least one activatable with actinic radiation bond per molecule

• Allyl alcohol or 4-butyl vinyl ether;
• Hydroxyalkyl esters of acrylic acid or methacrylic acid, in particular the Acrylic acid obtained by esterification of aliphatic diols, for example the above-described low molecular weight diols B), with acrylic acid or Methacrylic acid or by reaction of acrylic acid or methacrylic acid with an alkylene oxide, in particular hydroxyalkyl esters of acrylic acid or methacrylic acid in which the hydroxyalkyl group has up to 20 carbon atoms contains, such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3 Hydroxybutyl, 4-hydroxybutyl, bis (hydroxymethyl) cyclohexane acrylate or methacrylate; of these are 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate particularly advantageous and are therefore particularly preferred according to the invention used; or
• - reaction products of cyclic esters, such as. Epsilon-caprolactone, and these hydroxyalkyl or cycloalkyl esters.

Examples of suitable low molecular weight aliphatic compounds C) with at least two, in particular two, isocyanate-reactive functional groups are polyols, in particular diols, polyamines, in particular diamines, and amino alcohols. Usually, the polyols and / or polyamines in addition to the diols and / or Diamines in minor amounts are used to branch into the polyurethanes introduce. In the context of the present invention are subordinate amounts  To understand amounts that cause no gelling of the polyurethanes in their preparation. This applies mutatis mutandis to the amino alcohols.

Examples of suitable diols C) are ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, 1,2-, 1,3-, 1,4- or 1,5-pentanediol, 1,2-, 1,3-, 1,4-, 1,5- or 1,6 hexanediol, Hydroxypivalic acid neopentyl ester, neopentyl glycol, diethylene glycol, 1,2-, 1,3- or 1,4- Cyclohexanediol, 1,2-, 1,3- or 1,4-cyclohexanedimethanol, trimethylpentanediol, Ethylbutylpropanediol, the positionally isomeric diethyloctanediols, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-methylpropanediol-1,3, 2-phenyl-2-methylpropanediol-1,3, 2-propyl-2-ethylpropanediol-1,3, 2-di-tert-butylpropanediol-1,3, 2-butyl-2-propylpropanediol-1,3, 1-dihydroxymethyl-bi cyclo [2.2.1] heptane, 2,2-diethylpro-1,3-diol, 2,2-dipropylpropane-1,3-diol, 2-cyclo hexyl 2-methylpropanediol-1,3,2,5-dimethylhexanediol-2,5, 2,5-diethylhexanediol-2,5, 2-ethyl-5-methylhexanediol-2,5, 2,4-dimethylpentanediol-2,4, 2,3-dimethylbutanediol-2,3, Dihydroxymethylcyclohexane, bis (hydroxycyclohexyl) propane, tetramethylcyclobutanediol, Cyclooctanediol or norbornanediol.

Examples of suitable polyols C) are trimethylolethane, trimethylolpropane or glycerol, Pentaerythritol or homopentaerythritol or sugar alcohols such as threit or erythritol or Pentites such as arabitol, adonite or xylitol or hexites such as sorbitol, mannitol or dulcitol.

Examples of suitable diamines C) are hydrazine, ethylenediamine, propylenediamine, 1,4- Butylenediamine, piperazine, 1,4-cyclohexyldimethylamine, hexamethylenediamine-1,6, Trimethylhexamethylenediamine, methanediamine, isophoronediamine or 4,4'- Diaminodicyclohexylmethane.

Examples of suitable polyamines C) are diethylenetriamine, triethylenetetramine, Dipropylenediamine and dibutylenetriamine.

Examples of suitable amino alcohols C) are ethanolamine, diethanolamine or Triethanolamine.

Of these compounds C) diethanolamine offers particular advantages and is therefore preferably used according to the invention.  

Examples of suitable compounds D) with at least one isocyanate-reactive functional group and at least one dispersing functional group, especially a (potentially) anionic group, are mercapto, hydroxy, amino or iminocarboxylic acids, phosphonic acids or sulfonic acids such as mercaptoacetic acid (Thioglycolic acid), mercaptopropionic acid, mercaptosuccinic acid, hydroxyacetic acid, Hydroxydecanoic acid, hydroxydodecanoic acid, 12-hydroxystearic acid, Hydroxyethanesulfonic acid, hydroxypropanesulfonic acid, mercaptoethanesulfonic acid, Mercaptopropanesulfonic acid, aminopropanesulfonic acid, glycine, iminodiacetic acid, 2,2-di methylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2- Dimethylolpentanoic acid, α, δ-diaminovaleric acid, 3,4-diaminobenzoic acid, 2,4- Diaminotoluenesulfonic acid or 2,4-diamino-diphenyl ether sulfonic acid. They are in Amounts used that result in the acid numbers described above.

Examples of suitable neutralizing agents E) for the potentially anionic groups of Compound D) are alkali and alkaline earth hydroxides, oxides, carbonates or bicarbonates and ammonia or amines, such as. Trimethylamine, triethylamine, Tributylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, Diethylethanolamine, methyldiethanolamine, 2-aminomethylpropanol, Dimethylisopropylamine or dimethylisopropanolamine.

Examples of suitable compounds G) which differ from the compounds B) to F) and have an isocyanate-reactive functional group, are ethanol, propanol, n- Butanol, sec-butanol, tert-butanol, amyl alcohols, hexanols, fatty alcohols, phenol, Allyl alcohol or ethylhexylamine. They are preferably i. V. m. higher functional Compounds C) is used, in particular for gelling the polyurethanes in their To avoid production.

The preparation of the polyurethane to be used according to the invention can thus be controlled be that result in aqueous polyurethane dispersions containing liquid particles. However, the selection of the starting materials described above, in particular the starting products D) and A), are made according to type and quantity so that the Variation of glass transition temperature and / or acid number of polyurethanes finely divided solid particles result, i. h., That it is a powder slurry according to the invention.  

Preferably, these solid fine particles have an average particle size of 3.0 to 10 microns, especially 3.0 to 5 microns, on.

From a methodological point of view, the preparation of the aqueous polyurethane dispersion from the The starting materials described above no special features, but takes place according to the usual and known methods of preparation of aqueous Polyurethane dispersions, as described for example in the aforementioned, the Waterborne paints relating to patents are described. So will for example, in a preferred procedure in a first process step at least one compound B) with a molar excess of at least one Compound A) converted to an adduct which activatable with actinic radiation Contains bonds and free isocyanate groups. The adduct is in a second Process step with at least one compound D) and optionally C) to a Reacted prepolymers containing isocyanate groups. In another Process step is at least one neutralizing agent E) and optionally at least one compound C) is added so that a partially or completely neutralized prepolymer results. The neutralized prepolymer is in a fourth Process step implemented with a compound F). Should thereafter still free Isocyanate groups are present, these are preferably at least one Compounds G) and / or C) reacted, whereby the invention to be used Polyurethane results. This is transferred into an aqueous medium, whereby the According to the invention to be used polyurethane dispersion results.

The aqueous medium contains essentially water. In this case, the aqueous medium in minor amounts organic solvents curable with actinic radiation Reaktivverdünner, photoinitiators, initiators of radical polymerization and / or other paint additives and / or other dissolved solid, liquid or gaseous organic and / or inorganic, low and / or high molecular weight substances. in the For the purposes of the present invention, by the term "minor amount" is meant one Amount understood that does not cancel the aqueous character of the aqueous medium. However, the aqueous medium may also be pure water.

As radiation-curable reactive diluents are low molecular weight polyfunctional ethylenically unsaturated compounds into consideration. Examples of suitable compounds  of this type are esters of acrylic acid with polyols, such as neopentyl glycol diacrylate, Trimethylolpropane triacrylate, pentaerythritol triacrylate or pentaerythritol tetraacrylate; or Reaction products of hydroxyalkyl acrylates with polyisocyanates, in particular aliphatic polyisocyanates. In addition, on Römpp Lexikon Lacke and Printing inks, Georg Thieme-Verlag, Stuttgart-New York, 1998, "Reactive thinner", Page 491, referenced.

If photoinitiators are used with, they are in the invention to polyurethane dispersion used preferably in proportions of 0.1 to 10 wt .-%, 1 to 8 Wt .-% and in particular 2 to 6 wt .-%, each based on the total amount of Dispersion, included.

Examples of suitable photoinitiators are those of the Norrish II type, whose Mechanism of action on an intramolecular variant of the hydrogen Abstraction reactions, as in many ways in photochemical Reactions occur (for example, Römpp Chemie-Lexikon, 9th extended and revised edition, Georg Thieme-Verlag Stuttgart, Vol. 4, 1991, referenced) or cationic photoinitiators (for example, Römpp Lexikon Lacke and Druckfarben, Georg Thieme Verlag Stuttgart, 1998, pages 444 to 446, referenced), in particular benzophenones, benzoins or benzoin ethers or phosphine oxides. It can Also, for example, the commercially under the name Irgacure® 184, Irgacure® 1800 and Irgacure® 500 from Ciba Geigy, Genocure® MBF from Rahn and Lucirin® TPO BASF AG available products.

In addition to the photoinitiators common sensitizers such as anthracene can be effective in Quantities are used.

Furthermore, the polyurethane dispersion according to the invention may still contain at least one Initiator of thermal crosslinking included. These form radicals from 80 to 120 ° C, which start the crosslinking reaction. Examples of thermolabile radical initiators are organic peroxides, organic azo compounds or C-C cleaving initiators such as Dialkyl peroxides, peroxycarboxylic acids, peroxodicarbonates, peroxide esters, hydroperoxides, Ketone peroxides, azodinitriles or benzpinacol silyl ethers. C-C cleaving initiators are particularly preferred, since in their thermal cleavage no gaseous  Decomposition products are formed, which could lead to disturbances in the paint layer. When used with, their amounts are generally between 0.1 to 10 Wt .-%, preferably 0.5 to 8 wt .-% and in particular 1 to 5 wt .-%, respectively based on the total amount of the dispersion.

Examples of suitable further customary additives are transparent organic and inorganic fillers, thermally curable reactive diluents, low-boiling and / or high-boiling organic solvents ("long solvents"), UV absorbers, Light stabilizers, radical scavengers, catalysts for crosslinking, deaerating agents, Slip additives, polymerization inhibitors, defoamers, emulsifiers, wetting agents, Adhesion promoters, leveling agents, film-forming aids, rheology-controlling additives or Flame retardants. Further examples of suitable paint additives are in the textbook "Paint Additives" by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998, described. They are used in the usual and known, effective amounts.

Preferably, those aforementioned additives are selected with the Water are compatible and in particular are not decomposed by water.

The color and / or produced by the Erflndungsgemäßen method effect multi-layer finishes are what color, effect, gloss and D. O. I. (distinctiveness of the reflected image), of the highest optical quality, have a smooth, structure-free, hard, flexible and scratch-resistant surface, are weatherproof, chemical and etch resistant, do not yellow and show no cracking and Delamination of the layers.

The coated with these color and / or effect multi-layer coatings primed or unprimed substrates therefore have a particularly high Service life and a particularly high utility value, what they are for manufacturers, Users and end users are particularly attractive technically and economically makes.

example The preparation of a multicoat colorant coating after inventive method 1. The preparation of an allophanate from hexamethylene diisocyanate and 2- hydroxyethyl

The allophanate was prepared according to the German patent DE-A-198 60 041, Experimental Part 1.1, Product No. 6. To this was added hexamethylene diisocyanate under nitrogen coverage with 40 mol% (based on the isocyanate) 2- Mixed hydroxyethyl acrylate and heated to 80 ° C. After addition of 200 ppm by weight (based on the isocyanate) N, N, N-trimethyl-N- (2-hydroxypropyl) ammonium-2 ethylhexanoate, the reaction mixture was slowly heated to 120 ° C and this Reaction temperature maintained. At an isocyanate content of the reaction mixture of 13.5 Wt .-%, the reaction was by adding 250 ppm by weight (based on the isocyanate) Di (2-ethylhexyl) phosphate stopped. The reaction mixture was then in Thin-film evaporator at 135 ° C and 2.5 mbar of unreacted Hexamethylene diisocyanate freed. The resulting allophanate had after distillation an isocyanate content of 13.5 wt .-% and a viscosity of 810 mPa.s at 23 ° C.

2. The preparation of an isocyanate group-containing prepolymer

In a stirred tank, 100 parts by weight of the allophanate described above (see Section 1.), 0.13 part by weight of 2,6-di-tert-butyl-p-cresol and 0.1 part by weight Submitted hydroquinone monomethyl ether. After admixing 0.02 parts by weight Dibutyltin dilaurate of 17.5 parts by weight of 3,5-dimethylpyrazole was added Reaction mixture stirred at 70 ° C for three hours.

3. The preparation of the aqueous polyurethane dispersion

To the 2. resulting reaction mixture was 3.3 parts by weight Thioglycolic acid added. Thereafter, the reaction mixture became further stirred for three hours at 70 ° C and then cooled. The content of free Isocyanate groups were hereafter 3 wt .-%. After adding 9.6 Diethanolamine and 4, 4 parts by weight of triethylamine was the  Reaction mixture dispersed in water. This resulted in a stable dispersion with a z average particle size of 320 nm (measured with a PCS Malvern Zetasizer 1000).

For the application, the dispersion was added to a solids content of 30% by weight. % (1 hour, 130 ° C).

4. The preparation of a clearcoat to be used according to the invention

100 parts by weight of the products specified in para. 3. prepared dispersion were 0.1 Parts by weight of a commercially available leveling agent (BYK® 307 from Byk Chemie), 4.0 parts by weight of a commercially available photoinitiator (Genocure® MBF from the company Rahn Chemie), 1.0 parts by weight of a commercially available UV absorber (Tinuvin® 1130 Ciba Specialty Chemicals) and 0.8 parts by weight of a sterically hindered Amines (HALS) (Tinuvin® 292 from Ciba Specialty Chemicals) intimately mixed. The Clearcoat was ready to spray afterwards.

5. The preparation of the multicoat colorant coating

On with a commercial electrodeposition paint (Cathoguard® 500 BASF Coatings AG) cathodically coated steel panels (electrocoating with a Layer thickness of 18-22 microns) were with a cup gun initially a commercial aqueous filler (Ecoprime® R130 from BASF Coatings AG) and applied baked. This resulted in a surfacer coating with a layer thickness of 35 to 40 microns. Subsequently, a black aqueous basecoat was applied to the filler in the same way (Basecoat night black FV96-9400 from BASF Coatings AG) and applied pre-dried at 80 ° C for 10 min. After cooling the panels became a Layer from the according to para. 4. prepared clear coat with a cup gun in one Wet layer thickness of 150 microns applied and for 10 min at room temperature vented and pre-dried for 5 min at 80 ° C (wet-in-wet method).

Subsequently, the test panels were irradiated with UV radiation at a dose of 1,500 mJ / cm ² . They were then baked at 150 ° C for 30 minutes (Dual Cure). This resulted in a basecoat of a layer thickness of 16 .mu.m and a clearcoat of a layer thickness of 45 .mu.m.

The multi-layer coating prepared by the process according to the invention showed a high gloss of 87 ° according to DIN 67530 and a high hardness (pendulum hardness according to König: 195 s).

The scratch resistance of the multi-layer coating was determined after the brush test. For this test were the test panels were after application of the multi-layer coating stored at room temperature for at least 2 weeks before the test is performed has been.

The scratch resistance was determined by means of the BASF brush test described in FIG. 2 on page 28 of the article by P. Betz and A. Bartelt, Progress in Organic Coatings, 22 (1993), pages 27-37. 2000 g instead of the 280 g mentioned therein) was assessed as follows:
In the test, the paint surface was damaged with a screen cloth, which was loaded with a mass. The mesh and the paint surface were wetted abundantly with a detergent solution. The test panel was pushed back and forth by means of a motor drive in strokes under the screen mesh.

The test specimen was with nylon screen mesh (No. 11, 31 μm mesh size, Tg 50 ° C) be stretched eraser (4.5 × 2.0 cm, wide side perpendicular to the direction of the scratch). The Aufla weight was 2000 g.

Before each test, the mesh was renewed, while the running direction of the fabric was stitched parallel to the direction of the thread. About 1 ml of a freshly stirred 0.25% Persil solution was applied with a pipette before the eraser. The number of revolutions of the motor was adjusted so that 80 double strokes were executed in a time of 80 s. After the test, the remaining wash was rinsed with cold tap water and the test panel was dry-blown with compressed air. The gloss was measured according to DIN 67530 before and after damage (measuring direction perpendicular to the direction of the scratch):

Beginning: 87 ° after injury: 81 ° 2 h at 40 ° C: 84 ° 2 h at 60 ° C: 86 °

The brush test showed that the multi-layer coating a high scratch resistance and a had very good reflow behavior.

In addition, the scratch resistance was determined after the sand test. For this purpose, the surface of the paint was subjected to sand (20 g quartz silver sand 1.5-2.0 mm). The sand was placed in a beaker (ground plane cut), which was fixed firmly on the test panel. The same test panels were used as described above in the brush test. By means of a motor drive, the board with the cup and the sand was shaken. The movement of the loose sand caused damage to the paint surface (100 double strokes in 20 s). After the sand load, the test surface was cleaned from abrasion, carefully wiped under a cold water jet and then dried with compressed air. The gloss was measured according to DIN 67530 before and after damage (measuring direction perpendicular to the direction of the scratch):

Beginning: 87 ° after injury: 80 ° 2 h at 40 ° C: 82 ° 2 h at 60 ° C: 85 °

The sand test underpinned the high scratch resistance and the very good reflow behavior the multi-layer coating.

The BART (BASF ACID RESISTANCE TEST) was used to determine the resistance of the paint surface to acids, alkalis and water droplets. The multi-layer coating was subjected to further temperature loads on a gradient oven (30 min, 40 ° C and 70 ° C). The test substances (sulfuric acid 1%, 10%, 36%, sulfuric acid 6%, hydrochloric acid 10%, sodium hydroxide 5%, demineralized water: 1, 2) were previously used or 3 drops) defined with a dosing pipette. Following the action of the substances, these were removed under running water and the damage was assessed visually after 24 h according to a predetermined scale:

grading Appearance 0 no defect 1 slight mark 2 Marking / matting / no softening 3 Marking / dulling / color change / softening 4 Cracks / incipient etching 5 Clearcoat removed

Each single mark (spot) was evaluated and the result in a suitable Form (eg, suffrage for a temperature) recorded.

The results of the test can be found in the table.

table

The acid resistance of the multi-layer coating according to BART

The BART underpinned the high acid resistance of the multi-layer coating or the Clearcoat.

Claims (13)

Anspruch [en] A method for producing a multicoat color and / or effect coating on a primed or unprimed substrate in which a basecoat film and at least one clearcoat film are applied to one another, characterized in that at least one of the clearcoat films is curable thermally and with actinic radiation and at least one aqueous polyurethane dispersion containing or consisting of an acid number of 5.0 to 100 mg KOH / g, the

• A) at least one aliphatic polyisocyanate having an isocyanate functionality of 2.0 to 6.0,
• B) at least one compound having at least one isocyanate-reactive functional group and at least one bond activatable with actinic radiation,
• C) at least one low molecular weight aliphatic compound having at least two isocyanate-reactive functional groups,
• D) at least one compound having at least one isocyanate-reactive functional group and at least one dispersing functional group,
• E) at least one neutralizing agent for the dispersing functional groups of compound D),
• F) at least one blocking agent for isocyanate groups and / or at least one compound having at least one blocked isocyanate group and optionally
• G) at least one compound other than compounds B) to F) having an isocyanate-reactive functional group

is constructed, wherein the blocked isocyanate groups on the reaction of the blocking agent F) with the polyurethane prepolymers containing isocyanate groups, from the reaction of a stoichiometric excess of the compounds A) with the compounds B) and optionally C) and with an adequate dispersibility in aqueous media amount Compounds D) and E), are introduced into the polyurethane dispersion. 2. Thermally and actinic radiation curable powder slurry containing or consisting of at least one aqueous polyurethane dispersion of finely divided, solid particles, characterized in that the aqueous polyurethane dispersion has an acid number of 5.0 to 100 mg KOH / g and from

• A) at least one aliphatic polyisocyanate having an isocyanate functionality of 2.0 to 6.0,
• B) at least one compound having at least one isocyanate-reactive functional group and at least one bond activatable with actinic radiation,
• C) at least one low molecular weight aliphatic compound having at least two isocyanate-reactive functional groups,
• D) at least one compound having at least one isocyanate-reactive functional group and at least one dispersing functional group,
• E) at least one neutralizing agent for the dispersing functional groups of compound D),
• F) at least one blocking agent for isocyanate groups and / or at least one compound having at least one blocked isocyanate group and optionally
• G) at least one compound other than compounds B) to F) having an isocyanate-reactive functional group

is constructed, wherein the blocked isocyanate groups on the reaction of the blocking agent F) with the polyurethane prepolymers containing isocyanate groups, from the reaction of a stoichiometric excess of the compounds A) with the compounds B) and optionally C) and with an adequate dispersibility in aqueous media amount Compounds D) and E), are introduced into the polyurethane dispersion. 3. The method according to claim 1, characterized in that

• 1. a basecoat layer of a thermally and optionally curable with actinic radiation pigmented basecoat applied to the surface of the substrate and,
  • 1. (1.1) without curing, drying or partially curing or
  • 2. (1.2) Cures completely thermally and optionally with actinic radiation,

which one

• 1. a clearcoat I applied from the thermally and actinic radiation curable clearcoat I to the surface of the basecoat or basecoat and
  • 1. (2.1) together with the basecoat or
  • 2. (2.2) on its own

completely thermally and / or cured with actinic radiation;
or alternatively

• 1. a clearcoat I applied from a thermally and / or actinic radiation curable clearcoat I to the surface of the basecoat or the basecoat and
  • 1. (2.1) alone in part,
  • 2. (2.2) together with the basecoat partially or
  • 3. (2.3) together with the basecoat layer completely or
  • 4. (2.4) completely by itself

thermally and / or cured with actinic radiation, after which

• 1. a further clearcoat film II of a thermally and / or actinic radiation-curable clearcoat II applied to the surface of the clearcoat I or the clearcoat I, wherein at least one of the clearcoat films I and II is a curable thermally and with actinic radiation clearcoat, after which
  • 1. (3.1) the clearcoat film II alone or
  • 2. (3.2) together with the underlying, not yet completely cured lacquer layers

fully cured thermally and / or with actinic radiation, 4. The method according to claim 1 or 3 and the powder slurry according to claim 2, characterized in that contained in the polyurethane dispersion Polyurethane with actinic radiation activatable bonds, isocyanate-reactive functional groups, blocked isocyanate groups and dispersing functional Groups, in particular (partially) anionic groups containing.   5. The method according to any one of claims 1, 3 or 4 and the powder slurry according to Claim 2 or 4, characterized in that as compounds A) isocyanurate, Biurethane, allophanate, iminooxadiazinedione, urethane, urea, carbodiimide and / or urethdione groups having aliphatic polyisocyanates used become. 6. The method according to any one of claims 1 or 3 to 5 and the powder slurry according to one of claims 2, 4 or 5, characterized in that as with actinischer Radiation activatable bonds carbon-hydrogen single bonds or Carbon-carbon, carbon-oxygen, carbon-nitrogen, Carbon-phosphorus or carbon-silicon single bonds or Double bonds are used. 7. The method and the powder slurry according to claim 6, characterized in that the double bonds as (meth) acrylate, ethacrylate, crotonate, cinnamate, Vinyl ether, vinyl ester, dicyclopentadienyl, norbornenyl, isoprenyl, isoprenyl, Isopropenyl, allyl or butenyl groups; Dicyclopentadienyl, norbornenyl, Isoprenyl, isopropenyl, allyl or butenyl ether groups or Dicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl or Butenylestergruppen present. 8. The method according to any one of claims 1 or 3 to 7 and the powder slurry according to one of claims 2 or 4 to 7, characterized in that as isocyanate-reactive functional groups thio, hydroxyl, amino, imino, Carbamate and / or allophanate, especially thio, hydroxyl and Amino groups, are used. 9. The method according to any one of claims 1 or 3 to 8 and the powder slurry according to one of claims 2 or 4 to 8, characterized in that as (potentially) anionic groups carboxylic acid, sulfonic acid or phosphonic acid groups, in particular carboxylic acid groups. 10. The method according to any one of claims 1 or 3 to 9 and the powder slurry according to one of claims 2 or 4 to 9, characterized in that as  Blocking agents oximes and / or substituted pyrazoles, in particular ketoximes and / or dimethylpyrazole. 11. The method according to any one of claims 1 or 3 to 10 and the powder slurry after one of claims 2 or 4 to 10, characterized in that at least one of the clearcoats I and / or II at least one photoinitiator, at least one Reactive thinner for curing with actinic radiation at least one Initiator of thermal crosslinking and / or at least one customary paint additive contains. 12. Color and / or effect multicoat paint systems on primed or unprimed substrates, preparable by means of the method according to one of Claims 1 or 3 to 11 and / or with the aid of the powder slurry according to one of Claims 2 or 4 to 11.