EP1242496A1 - Method for producing coatings from coating materials, which can be cured thermally and by using actinic radiation - Google Patents

Abstract

The invention relates to a method for producing coatings from coating materials, which can be cured thermally and by using actinic radiation, on primed or non-primed substrates by: (1) applying at least one coating material, which can be cured thermally and by using actinic radiation, to a primed or non-primed substrate, whereby producing a layer that is comprised of the coating material, and; (2) curing the layer by using heat and actinic radiation. The inventive method is characterized in that a coating material is used that consists of:(A) compounds, which, with a statistical mean, contain at least one free isocyanate group and at least one bond per molecule that can be activated by means of actinic radiation; (B) (meth)acrylate copolymerizates that contain hydroxyl groups, and optionally of; C) additives selected from the group comprised of pigments, fillers, nanoparticles, bonding agents, reactive diluents, cross-linking agents for thermal curing, solvents, water, UV absorbers, light stabilizers, radical scavengers, initiators, catalysts for thermal cross-linking, degassing agents, slip additives, polymerization inhibitors, defoaming agents, emulsifiers, wetting and dispersing agents, adhesion promoters, flow-controlling agents, film-forming auxiliary agents, sag control agents (SCA), rheology controlling additives (thickeners), flame proofing agents, siccatives, drying agents, skinning inhibitors, corrosion inhibitors, waxes and delustering agents.

Description

Process for the production of coatings from coating materials curable thermally and with actinic radiation

The present invention relates to a new process for producing coatings from coating materials curable thermally and with actinic radiation.

Coating materials curable thermally and with actinic radiation, which are also referred to as dual-cure coating materials, and processes for producing coatings therefrom are known from European patent specification EP-A-0 928 800. The known coating material necessarily contains a urethane (meth) acrylate which has (meth) acrylate groups and free isocyanate groups, a UV polymer initiator (photoinitiator) which initiates the radical polymerisation and an isocyanate-reactive compound. Possible isocyanate-reactive compounds are polyols such as polyesters from diols and triols and diacarboxylic acids, hindered amines from maleic esters and cycloaliphatic primary diamines, polyether polyols or hydroxyl-containing (meth) acrylate copolymers.

The known dual-cure coating material has the advantage that, on the one hand, an incomplete thermal hardening, which is consciously carried out, for example, to protect thermally sensitive substrates, with UV hardening, or an incomplete hardening, for example in the shadow areas of complex-shaped substrates can be compensated with UV light with the thermal hardening, so that overall a very good result results in both cases.

However, it is disadvantageous that the use of photo initiators leads to sometimes odor-intensive emissions of decay products and or to yellowing of the coatings. The object of the present invention is to find a new process for the production of coatings from dual-cure coating materials which, while preserving the advantages of the dual-cure systems described, delivers coatings which are non-yellowing and emission-free.

Accordingly, the new process for the production of coatings from thermally and actinic radiation-curable coating materials on primed and unprimed substrates was carried out

(1) application of at least one thermally and with actinic radiation curable coating material to the primed or unprimed substrate or to a basecoat layer thereon, whereby a layer results from the coating material, and

(2) curing the layer with heat and current radiation,

found using a coating material consisting of

A) at least one compound which, on a statistical average, has at least one free isocyanate group and at least one bond which can be activated with actinic radiation per molecule and

B) at least one hydroxyl-containing (meth) acrylate copolymer

or from at least one component (A), at least one component (B) and

C) at least one additive selected from the group consisting of color and / or effect pigments, organic and inorganic, transparent or opaque fillers, nanoparticles, oligomers and polymeric binders, thermally and / or reactive thinners curable with actinic radiation, crosslinking agents for thermal curing, low and high-boiling organic solvents ("long solvents"), water, UV absorbers, light stabilizers, radical scavengers, thermolabile radical initiators, catalysts for thermal

Crosslinking, deaerating agents, slip additives, polymerization inhibitors. Defoamers, emulsifiers, wetting and diperging agents, adhesion promoters, leveling agents, film-forming aids, sag control agents (SCA), rheology-controlling additives (thickeners), flame retardants, siccatives, drying agents, skin-preventing agents,

Corrosion inhibitors, waxes and matting agents;

consists.

In the following, the new process for producing coatings from coating materials curable thermally and with actinic radiation is referred to as the “process according to the invention”.

In view of the prior art, it was surprising and unforeseeable for the person skilled in the art that the special combination of the components (A) and (B) or (A), (B) and (C) is thermal and without the use of photoinitiators can be cured with actinic radiation, the curing with actinic radiation taking place at comparatively low temperatures below 50 ° C.

The method according to the invention is used to produce coatings, in particular single-layer and multi-layer clearcoats and color and / or effect coatings, on primed or unprimed substrates. Suitable substrates are all surfaces to be painted which are not damaged by hardening of the paintwork thereon with combined use of heat and actinic radiation; these are e.g. B. metals, plastics, wood, ceramics, stone, textiles, fiber composites, leather, glass, glass fibers, glass and rock wool, mineral and resin-bound building materials, such as plaster and cement boards or roof tiles, as well as composites of these materials. Accordingly, the method according to the invention is also suitable for applications outside of automotive painting. This is particularly important for the painting of furniture and industrial painting, including coil coating, container coating and the impregnation or coating of electrical components. As part of industrial painting, it is suitable for painting practically all parts for private or industrial use such as radiators, household appliances, small parts made of metal such as screws and nuts, hubcaps, rims, packaging or electrical components such as motor windings or transformer windings.

In the case of electrically conductive substrates, primers can be used which are produced in a customary and known manner from electrocoat materials (ETL). Both anodic (ATL) and cathodic (KTL) electrodeposition coatings, but especially KTL, come into consideration for this. In the case of metal, the substrate can also be subjected to a surface treatment, for example galvanizing or phosphating or anodizing. have undergone

In automotive OEM painting in particular, a filler or a stone chip protection primer is applied to the fully cured or only dried electrodeposition coating (ETL). This layer of paint is cured either on its own or together with the electrocoat layer below. The applied filler layer can also only be dried or partially cured, after which it is coated with the lacquer layers above and, if necessary, with the electrocoat layer underneath is fully cured (extended wet-on-wet process). In the context of the present invention, the term primer also includes the combination of electro-dip coating and filler coating or stone chip protection primer.

With the method according to the invention, primed or non-primed plastics such. B. 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 (short names according to DIN 7728T1) can be painted. The plastics to be painted can of course also be polymer blends, modified plastics or fiber-reinforced plastics. The plastics typically used in vehicle construction, in particular motor vehicle construction, can also be used.

In the case of non-functionalized and / or non-polar substrate surfaces, these can be subjected to a pretreatment, such as with a plasma or with flame treatment, or provided with a hydro primer in a known manner before the coating.

In a first advantageous variant of the process according to the invention, in the first process step the coating material described below, to be used according to the invention and curable thermally and with actinic radiation, is applied to the primed or unprimed substrate, resulting in a layer of the dual-cure coating material to be used according to the invention. This process variant is used in particular in the production of single-layer clearcoats or color and / or effect coatings. In a second advantageous variant of the method according to the invention, in the first method step the dual-cure coating material to be used according to the invention is applied to at least one basecoat layer located on the substrate. The basecoat layer can also be a pigmented dual-cure coating material. The base lacquer layer is preferably merely dried or partially cured, so that it can be cured together with the layer made of the dual-cure coating material (wet-on-wet method).

In a third variant of the process according to the invention, the pigmented dual-cure coating material to be used according to the invention is applied in the first process step and covered with a customary and known clearcoat, after which the two layers are cured together (wet-on-wet process).

The second and the third, but in particular the second, variant of the method according to the invention are used above all for the production of multi-layer color and / or effect coatings.

The application of the dual-cure coating material to be used according to the invention can be carried out by all customary application methods, such as e.g. Spraying, knife coating, painting, pouring, diving, watering. Dribbling or rolling take place. The substrate to be coated can rest as such, with the application device or system being moved. However, the substrate to be coated, in particular a coil, can also be moved, the application system being stationary relative to the substrate or being moved in a suitable manner.

Spray application methods are preferably used, such as compressed air spraying. Airless spray. High rotation, electrostatic spray application (ESTA), possibly combined with hot spray applications such as hot air - hot spraying. The application can be carried out at temperatures of max. 70 to 80 ° C are carried out so that suitable application viscosities are achieved without a change or damage to the dual-cure coating material to be used according to the invention and its overspray, which may need to be reprocessed, occurring under the briefly acting thermal load. For example, hot spraying can be designed such that the dual-cure coating material to be used according to the invention is heated only very briefly in or shortly before the spray nozzle.

The spray booth used for the application can be operated, for example, with a circulation that can be tempered, if necessary, which is equipped with a suitable absorption medium for the overspray, e.g. B. the dual-cure coating material to be used according to the invention itself is operated.

The application is preferably carried out when illuminated with visible light of a wavelength of more than 550 μm or with exclusion of light if the water-based lacquer is curable thermally and with actinic radiation. This avoids a material change or damage to the dual-cure coating material to be used according to the invention and to the overspray.

In general, the dual-cure coating materials to be used according to the invention are applied in a wet layer thickness such that, after they have hardened, coatings result in the layer thicknesses necessary and advantageous for their functions. In the case of a base coat they are 5 to 50, preferably 5 to 40, particularly preferably 5 to 30 and in particular 10 to 25 μm, and in the case of a clear coat they are 10 to 100, preferably 15 to 80, particularly preferably 20 to 75 and in particular 25 to 70 μm. Of course, the application methods described above can also be used in the production of the other lacquer layers in the process according to the invention.

In the context of the method according to the invention, the layer of the dual-cure coating material to be used according to the invention is cured thermally and with actinic radiation after its application. The methods of thermal curing described below and the methods of curing with actinic radiation described below are preferably used here.

Under actinic radiation, electromagnetic radiation is like visible light,

UV radiation and X-rays, in particular UV radiation, or

To understand corpuscular radiation like electron radiation. UV radiation and or electron radiation, in particular UV radiation, are preferably used.

In the context of the method according to the invention, curing can take place immediately after the application of the layer made of the dual-cure coating material to be used according to the invention. If necessary, layers of paint that are not yet fully cured can also be cured. According to the invention, it is advantageous if the primer is already fully cured.

Curing can take place after a certain rest period or flash-off time. It can have a duration of 30 s to 2 h, preferably 1 min to 1 h and in particular 1 min to 45 min. The rest time is used, for example, for the course and degassing of the layers and for the evaporation of volatile constituents such as any solvent that may still be present. When curing with actinic radiation, a dose of 1,000 to 2,000, preferably 1,100 to 1,900, particularly preferably 1,200 to 1,800, very particularly preferably 1,300 to 1,700 and in particular 1,400 to 1,600 mJ / cm ^{2 is} preferably used. If necessary, this hardening can be supplemented with actinic radiation from other radiation sources. In the case of electron beams, work is preferably carried out under an inert gas atmosphere. This can be ensured, for example, by supplying carbon dioxide and / or nitrogen directly to the surface of the clear lacquer layer I. In the case of curing with UV radiation, it is also possible to work under inert gas in order to avoid the formation of ozone.

The usual and known radiation sources and optical auxiliary measures are used for curing with actinic radiation. Examples of suitable radiation sources are flash lamps from VISIT, high-pressure or low-pressure mercury vapor lamps, which may be doped with lead to open a radiation window up to 405 nm, or electron beam sources. Their arrangement is known in principle and can be adapted to the conditions of the workpiece and the process parameters. In the case of workpieces of complex shape, such as those intended for automobile bodies, the areas (shadow areas) which are not directly accessible to radiation, such as cavities, folds and other undercuts due to construction, can be combined with point, small area or all-round emitters, combined with an automatic movement device for irradiating cavities or Edges to be (partially) cured.

The facilities and conditions of these hardening methods are described, for example, in R. Holmes, UN. and EB Curing Formulations for Printing Inks, Coatings and Paints, SITA Technology, Academic Press, London, United Kindom 1984. In this case, the curing can take place in stages, ie by multiple exposure or irradiation with actinic radiation. This can also be done alternately, ie alternately curing with UV radiation and electron radiation.

The thermal curing also has no special features in terms of method, but is carried out according to the customary and known methods, such as heating in a forced air oven or irradiation with IR lamps. As with curing with actinic radiation, thermal curing can also be carried out in stages. The thermal curing advantageously takes place at temperatures below 100 ° C., in particular 90 ° C.

Thermal curing and curing with actinic radiation are used simultaneously or in succession. If the two curing methods are used in succession, thermal curing can be started, for example, and curing with actinic radiation can be ended. In other cases, it may prove advantageous to start and end the curing with actinic radiation. Particular advantages result if the layer of the dual-cure coating material to be used according to the invention is first cured thermally in two separate process steps and then with actinic radiation.

Of course, the curing methods described above can also be used in the process according to the invention for curing the other lacquer layers.

The single- or multi-layer clearcoat or color and / or effect coating resulting from the process according to the invention can also be coated with a layer of an organically modified ceramic material, as it is commercially available, for example, under the brand Ormocer®.

The dual-cure coating material to be used for the process according to the invention consists of the two components (A) and (B) or the three components (A), (B) and (C).

Constituent (A) is at least one compound which contains on average at least one, in particular at least two, free isocyanate group (s) and at least one, in particular at least two, bonds which can be activated with actinic radiation per molecule. Compound (A) is preferably free from aromatic structures.

In the context of the present invention, a bond which can be activated with actinic radiation is understood to mean a bond which becomes reactive when irradiated with actinic radiation and which undergoes polymerization reactions and / or crosslinking reactions with other activated bonds of its type which take place according to 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 are therefore used with very particular preference in accordance with the invention. For the sake of brevity, they are referred to below as "double bonds".

Particularly suitable double bonds are, for example, in (meth) acrylate,

Ethacrylate, crotonate, cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl,

Norbomenyl, isoprenyl, isopropenyl, AUyl or butenyl groups; Dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, allyl or Contain butenyl ether groups or dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, AUyl or butenyl ester groups. Of these, the acrylate groups offer very special advantages, which is why they are used according to the invention in a particularly preferred manner.

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

The compound (A) can be obtained by reacting polyisocyanates which contain on average at least 2.0, preferably more than 2.0 and in particular more than 3.0 isocyanate groups per molecule with compounds which have at least one, in particular one, contain bond which can be activated with actinic radiation and contain at least one, in particular one, isocyanate-reactive group.

There is basically no upper limit to the number of isocyanate groups in the polyisocyanates; According to the invention, however, it is advantageous if the number does not exceed 15, preferably 12, particularly preferably 10, very particularly preferably 8.0 and in particular 6.0.

Examples of suitable polyisocyanates are polyurethane prepolymers containing isocyanate groups, which can be prepared by reacting polyols with an excess of preferably aliphatic and cycloaliphatic diisocyanates and are preferably of low viscosity. In the context of the present invention, the term “cycloaliphatic diisocyanate” denotes a diisocyanate in which at least one isocyanate group is bonded to a cycloaliphatic radical. Examples of suitable cycloaliphatic diisocyanates are isophorone diisocyanate (= 5-isocyanato-1-isocyanatomethyl-1, 3, 3-trimethyl-cyclohexane), 5-isocyanato-1 - (2-isocyanatoeth-l-yl) -l, 3,3-trimethyl -cyclohexane, 5-isocyanato- 1- (3-isocyanatoprop-l-yl) -l, 3,3-trimethyl-cyclohexane, 5-isocyanato- (4-isocyanatobut-l-yl) -l, 3,3-trimethyl -cyclohexane, l-isocyanato-2- (3-isocyanatoprop-l-yl) cyclohexane, 1-isocyanato-2- (3-isocyanatoeth-l -yl) cyclohexane, 1-isocyanato-2- (4-isocyanatobut-l -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, especially isophorone diisocyanate.

Examples of suitable acyclic aliphatic diisocyanates to be used according to the invention are trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, ethyl ethylene diisocyanate,

Trimethylhexane diisocyanate, heptane methylene diisocyanate or diisocyanates derived from dimer fatty acids, as sold by the Henkel company under the trade name DDI 1410 and described in the patents DO 97/49745 and WO 97/49747, in particular 2-heptyl-3,4-bis (9 - isocyanatononyl) -l-pentyl-cyclohexane, or 1,2-, 1,4- or 1,3-

Bis (isocyanatomethyl) cyclohexane, 1,2-, 1,4- or 1,3-bis (2-isocyanatoeth-l-yl) cyclohexane, 1,3-bis (3-isocyanatoprop-l-yl) cyclohexane or 1, 2-, 1,4- or 1,3-

Bis (4-isocyanatobut-l-yl) cyclohexane.

Of these, hexamethylene diisocyanate is of particular advantage and is therefore used with very particular preference in accordance with the invention.

It can also have isocyanurate, biuret, allophanate, iminooxadiazinedione, urethane, urea, carbodiimide and / or uretdione groups Polyisocyanates are used which are prepared in a customary and known manner from the diisocyanates described above. Examples of suitable production processes and polyisocyanates are, for example, from the patents CA-A-2,163,591, US-A-4,419,513, US-A-4,454,317, EP-A-0 646 608, US-A-4,801,675, EP-A-0 183 976, DE-A-40 15 155, EP-A-0 303 150, EP-A-0 496 208, EP-A-0 524 500, EP-A-0 566 037, US-A-5,258,482, US- A-5,290,902, EP-A-0 649 806, DE-A-42 29 183 or EP-A-0 531 820.

Examples of suitable compounds which contain at least one bond which can be activated with actinic radiation and at least one isocyanate-reactive group are

Allyl alcohol or 4-butyl vinyl ether;

- Hydroxyalkyl esters of acrylic acid or methacrylic acid, especially acrylic acid, which are obtainable by esterification of aliphatic diols, for example the low-molecular diols B) described above, 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 contains up to 20 carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl, bis (hydroxymethyl) cyclohexane acrylate or methacrylate; Of these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are particularly advantageous and are therefore used with particular preference in accordance with the invention; or

Reaction products from cyclic esters, such as epsilon-caprolactone, and these hydroxyalkyl or cycloalkyl esters. The polyisocyanates are reacted with the compounds which contain at least one bond which can be activated with actinic radiation and at least one isocyanate-reactive group in a molar ratio such that, on average, at least one free isocyanate group remains per molecule.

From a methodological point of view, this implementation has no peculiarities, but takes place as described, for example, in European Patent EP-A-0 928 800.

The content of compounds (A) in the dual-cure coating materials to be used according to the invention can vary very widely. It depends in particular on the functionality and the amount of component (B) and any reactive diluent (C) present.

The dual-cure coating material of the invention further consists of at least one hydroxyl-containing (meth) acrylate copolymer (B).

The (meth) acrylate copolymers (B) containing hydroxyl groups contain primary and / or secondary hydroxyl groups. It is a very important advantage of the process according to the invention that both types of hydroxyl groups can be used. This enables the reactivity of the (meth) acrylate copolymers (B) containing hydroxyl groups to be controlled in a targeted manner via steric effects.

Highly suitable hydroxyl-containing (meth) acrylate copolymers (B) are obtained by copolymerizing the olefinically unsaturated monomers (b) described below, at least one of which contains at least one hydroxyl group and is essentially free of acid groups.

Examples of suitable monomers containing hydroxyl groups (b1) are hydroxyalkyl esters of acrylic acid, methacrylic acid of another alpha, beta ethylenically unsaturated carboxylic acid which is derived from an alkylene glycol which is esterified with the acid, or can be obtained by reacting the acid with an alkylene oxide, in particular hydroxyalkyl esters of acrylic acid, methacrylic acid or ethacrylic acid in which the hydroxyalkyl group contains up to 20 carbon atoms, such as 2 -Hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl acrylate, methacrylate, ethacrylate or crotonate; 1,4-bis (hydroxymethyl) cyclohexane, octahydro-4,7-methano-1H-indene-dimethanol or methyl propanediol monoacrylate, monomethacrylate, monoethacrylate or monocrotonate; or reaction products from cyclic esters, such as, for example, epsilon-caprolactone and these hydroxyalkyl esters; or olefinically unsaturated alcohols such as allyl alcohol or polyols such as trimethylolpropane mono- or diallyl ether or pentaerythritol mono-, di- or triallyl ether. These more functional

Monomers (bl) are generally only used in minor amounts. In the context of the present invention, minor amounts of higher-functional monomers are understood to mean amounts which do not lead to crosslinking or gelling of the polyacrylate resins. The proportion of trimethylolpropane diallyl ether can thus be 2 to 10% by weight, based on the total weight of the monomers (b1) to (b6) used to prepare the (meth) acrylate copolymers (B) containing hydroxyl groups. be. The monomers (bl) can be used as the sole monomers (b) using at least one (meth) acrylate (bl). According to the invention, however, it is advantageous to use them in combination with other monomers (b).

Examples of suitable further monomers (b) are:

Monomers (b2):

(Meth) acrylic or alkyl cycloalkyl esters with up to 20 carbon atoms in the alkyl radical, especially methyl. Ethyl, propyl, n-butyl, sec.-butyl, tert- Butyl, hexyl, ethylhexyl, stearyl and lauryl acrylate or methacrylate; cycloaliphatic (meth) acrylic acid esters, especially cyclohexyl, isobomyl, dicyclopentadienyl, octahydro-4,7-methano-1H-indene methanol or tert-butylcyclohexyl (meth) acrylate; (Meth) acrylic acid oxaalkyl ester or oxacycloalkyl ester such as ethyl triglycol (meth) acrylate and

Methoxyoligoglycol (meth) acrylate with a molecular weight Mn of preferably 550; or other ethoxylated and / or propoxylated hydroxyl-free (meth) acrylic acid derivatives. These can be used in minor amounts of higher functional (meth) acrylic acid alkyl or cycloalkyl esters such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, pentane-1, 5-diol, hexane, 1,6-diol, octahydro 4,7-methano-1H-indene-dimethanol or cyclohexane-1,2-, 1,3- or -1,4-diol-di (meth) acrylate; Trimethylolpropane di- or tri (meth) acrylate; or pentaerythritol di, tri or tetra (meth) acrylate; contain. In the context of the present invention, minor amounts of higher-functional monomers (b2) are understood to mean those amounts which do not lead to crosslinking or gelling of the polyacrylate resins.

Monomers (b3): At least one acid group, preferably a carboxyl group, ethylenically unsaturated monomer carrying per molecule or a mixture of such monomers. Acrylic acid and / or methacrylic acid are particularly preferably used as component (b3). However, other ethylenically unsaturated carboxylic acids with up to 6 carbon atoms in the molecule can also be used. Examples of such acids are ethacrylic acids, crotonic acid, maleic acid, fumaric acid and itaconic acid. Furthermore, ethylenically unsaturated sulfonic or phosphonic acids or their partial esters can be used as component (b3). Other suitable monomers (b3) are maleic acid mono (meth) acryloyloxyethyl ester, succinic acid mono (meth) acryloyloxyethyl ester and phthalic acid mono (meth) acryloyloxyethyl ester. Monomers (b4):

Vinyl esters of monocarboxylic acids with 5 to 18 carbon atoms in the molecule, branched in the alpha position. The branched monocarboxylic acids can be obtained by reacting formic acid or carbon monoxide and water with olefins in the presence of a liquid, strongly acidic catalyst; the olefins can be cracked products of paraffinic hydrocarbons, such as mineral oil fractions, and can contain both branched and straight-chain acyclic and / or cycloaliphatic olefins. When such olefins are reacted with formic acid or with carbon monoxide and water, a mixture of carboxylic acids is formed in which the carboxyl groups are predominantly located on a quaternary carbon atom. Other olefinic starting materials are e.g. Propylene trimer, propylene tetramer and diisobutylene. However, the vinyl esters can also be prepared from the acids in a manner known per se, e.g. by allowing the acid to react with acetylene. Because of the good availability, vinyl esters of saturated aliphatic monocarboxylic acids having 9 to 11 carbon atoms which are branched on the alpha carbon atom are particularly preferably used.

Monomers (b5):

Reaction product of acrylic acid and / or methacrylic acid with the glycidyl ester of a monocarboxylic acid with 5 to 18 carbon atoms per molecule branched in the alpha position. The reaction of acrylic or methacrylic acid with the glycidyl ester of a carboxylic acid with a tertiary alpha carbon atom can be carried out before, during or after the polymerization reaction. The reaction product of acrylic and / or methacrylic acid with the glycidyl ester of Versatic® acid is preferably used as component (b5). This glycidyl ester is commercially available under the name Cardura® E10. In addition, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pages 605 and 606. Monomers (b6):

Essentially free of ethylenically unsaturated monomers such as

Olefins such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene,

Cyclohexene, cyclopentene, norbornene, butadiene, isoprene, cyclopentadiene and / or dicyclopentadiene;

(Meth) acrylic saxaxides such as (meth) acrylic acid amide, N-methyl, N, N-dimethyl, N-ethyl, N, N-diethyl, N-propyl, N, N-dipropyl, N-butyl,

N, N-dibutyl, N-cyclohexyl and / or N, N-cyclohexyl-methyl- (meth) acrylic acid amide;

Monomers containing epoxy groups, such as the glycidyl ester of acrylic acid, methacrylic acids, ethacrylic acids, crotonic acid, maleic acid,

Fumaric acid and / or itaconic acid;

vinyl aromatic hydrocarbons, such as styrene, alpha-alkylstyrenes, in particular alpha-methylstyrene, arylstyrenes, in particular diphenylethylene, and / or vinyltoluene:

Nitriles such as acrylonitrile and / or methacrylonitrile:

Vinyl compounds such as vinyl chloride, vinyl fluoride, vinylidene dichloride, vinylidene difluoride; N-vinylpyrrolidone; Vinyl ethers such as ethyl vinyl ether. n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether,

Isobutyl vinyl ether and / or vinyl cyclohexyl ether; Vinyl esters such as vinyl acetate, vinyl propionate. Butyrate. Vinyl pivalate, vinyl ester of Versatic® acids, which are sold under the brand name VeoVa® by the company Deutsche Shell Chemie (in addition, Römpp Lexicon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, page 598 and pages 605 and 606, referenced) and / or the vinyl ester of 2-methyl-2-ethylheptanoic acid; and or

- Polysiloxane macromonomers, which have a number average molecular weight

Mn from 1,000 to 40,000, preferably from 2,000 to 20,000, particularly preferably 2,500 to 10,000 and in particular 3,000 to 7,000 and on average 0.5 to 2.5, preferably 0.5 to 1.5, ethylenically unsaturated double bonds per molecule, such as they in DE-A-38 07 571 on pages 5 to 7, DE-A 37 06 095 in columns 3 to 7, the

EP-B-0 358 153 on pages 3 to 6, in US-A 4,754,014 in columns 5 to 9, in DE-A 44 21 823 or in the international patent application WO 92/22615 on page 12, line 18 to page 18, line 10, or acryloxysilane-containing vinyl monomers, which can be prepared by reacting hydroxyl-functional silanes with epichlorohydrin and then reacting the reaction product with methacrylic acid and or hydroxyalkyl esters of (meth) acrylic acid.

According to the invention, it is particularly advantageous to select the monomers (b) in such a way that hydroxyl-containing (meth) acrylate copolymers (B) result, which preferably have an OH number of 100 to 250, preferably 130 to 210, preferably acid numbers of 0 to 80, preferably 0 to 50, very particularly preferably 0 to 15, preferably glass transition temperatures Tg from -25 to +80

° C, preferably -20 to +40 ° C, and preferably number average molecular weights of 1,500 to 30,000, preferably 1,500 to 15,000, very particularly preferably 1,500 to 5,000 (determined by

Gel permeation chromatography with polystyrene as the internal standard).

The glass transition temperature Tg of the (meth) acrylate copolymers (B) containing hydroxyl groups is determined by the type and amount of those used Monomers (bl) and optionally (b2), (b3), (b4), (b5) and or (b6) determined. The person skilled in the art can select the monomers (b) with the aid of the following formula from Fox, with which the glass transition temperatures Tg of (co) polymers, in particular polyacrylate resins, can be approximately calculated:

n = x 1 / Tg = Σ Wn / Tg _n ; Σ _n W _n = ln = l

Tg = glass transition temperature of the hydroxyl group

(Meth) acrylate copolymer (B) W _n = weight fraction of the nth monomer

Tg _n = glass transition temperature of the homopolymer from the nth monomer x = number of different monomers

From a methodological point of view, the preparation of the hydroxyl-containing (meth) acrylate copolymers (B) has no special features, but is carried out according to the customary and known methods of radical polymerization in the presence of at least one polymerization initiator in bulk or in solution.

Examples of suitable polymerization initiators are free radical initiators such as dialkyl peroxides such as di-tert-butyl peroxide or dicumyl peroxide; Hydroperoxides such as cumene hydroperoxide or tert-butyl hydroperoxide; Peresters, such as tert-butyl perbenzoate, tert-butyl perpivalate, tert-butyl per-3,5,5-trimethyl hexanoate or tert-butyl per-2-ethyl hexanoate; Azodinitriles such as azobisisobutyronitrile; CC-cleaving initiators such as benzpinacol silyl ether. Oil-soluble initiators are preferably used. The initiators will preferably in an amount of 0.1 to 25% by weight, particularly preferably from 0.75 to 10% by weight, based on the total weight of the monomers (b).

The polymerization is expediently carried out at a temperature of 80 to 200 ° C., preferably 110 to 180 ° C.

The organic solvents (C) described below which are inert to isocyanate groups, in particular mixtures of aromatic hydrocarbons or esters, ethers and or ketones, or reactive diluents (C) for thermal crosslinking are preferably used as solvents. The solvents can serve as additive (C) in the dual-cure coating material to be used according to the invention.

The (meth) acrylate copolymers (B) containing hydroxyl groups can be prepared by a two-stage process or a one-stage process.

In the two-stage process

1. a mixture of the monomers (bl) and optionally (b2), (b4), (b5) and / or (b6) or a mixture of parts of the monomers (bl) and optionally (b2), (b4), ( b5) and / or (b6) is polymerized in an organic solvent and

2. after at least 60% by weight of the mixture consisting of (bl) and optionally (b2), (b4) (b5) and / or (b6) has been added, the monomer (b3) and any present Rest of the monomers (bl) and optionally (b2), (b4). (b5) and / or (b6) added and further polymerized. In addition, however, it is also possible to initially introduce the monomers (b4) and / or (b5) together with at least part of the solvent and to meter in the remaining monomers. In addition, the monomers (b4) and / or (b5) can also be added only partially together with at least part of the solvent and the rest of these monomers can be added as described above. For example, at least 20% by weight of the solvent and about 10% by weight of the monomers (b4) and (b5) and, if appropriate, parts of the monomers (bl) and (b6) are preferably introduced.

It is preferred that the initiator feed be started some time, generally about 1 to 15 minutes, before the monomers feed. A method is further preferred in which the initiator addition begins at the same time as the addition of the monomers and is terminated about half an hour after the addition of the monomers has ended. The initiator is preferably added in a constant amount per unit of time. After the addition of the initiator has ended, the reaction mixture is kept at the polymerization temperature (as a rule 1.5 hours) until all of the monomers used have essentially been completely reacted. "Substantially completely converted" is intended to mean that preferably 100% by weight of the monomers used have been reacted, but it is also possible that a low residual monomer content of at most up to about 0.5% by weight, based on the Weight of the reaction mixture can remain unreacted.

The monomers (b) for the preparation of the hydroxyl-containing (meth) acrylate copolymers (B) are preferably polymerized with a not too high polymerization solid, preferably with a polymerization solid of 80 to 50% by weight, based on the monomers (b) ,

The preparation of the (meth) acrylate copolymers (B) containing hydroxyl groups also has no particular features in terms of apparatus, but takes place with the help of the methods known and known in the plastics field of continuous or discontinuous copolymerization under normal pressure or overpressure in stirred tanks, autoclaves, tubular reactors or Taylor reactors.

Examples of suitable copolymerization processes are described in the patents DE-A-197 09 465, DE-C-197 09 476, DE-A-28 48 906, DE-A-195 24 182, EP-A-0 554 783, WO 95 / 27742 or WO 82/02387.

Examples of suitable hydroxyl-containing (meth) acrylate copolymers (B) are commercially available and are sold, for example, by Bayer AG under the Desmophen® A brand, DSM under the Uracron® brand and Synthopol under the Synthalat® brand.

The content of hydroxyl-containing (meth) acrylate copolymers (B) in the dual-cure coating materials to be used according to the invention can vary very widely. It depends in particular on the functionality and the amount of component (A) and any reactive diluent (C) that is present.

The constituents (A) and (B) or (B) and (C) and (A) are preferably used in a quantitative ratio (B): (A) or [(B) + (C)]: (A) that the molar ratio of hydroxyl groups to isocyanate groups is 3: 1 to 1: 2, preferably 2: 1 to 1: 1, 5 and in particular 1.5: 1 to 1: 1.

The third component of the dual-cure coating material to be used according to the invention is at least one additive (C), selected from the group consisting of color and or effect pigments, organic and inorganic, transparent or opaque fillers, nanoparticles. oligomeric and polymeric binders, thermal and / or with actinic Radiation-curable reactive thinners, crosslinking agents for thermal curing, low and high-boiling organic solvents ("long solvents"), water, UV absorbers, light stabilizers, radical scavengers, thermolabile free radical initiators, catalysts for thermal crosslinking, deaerating agents, slip additives, anti-foaming agents, inhibitors, Emulsifiers, wetting and diperging agents, adhesion promoters, leveling agents, film-forming aids, sag control agents (SCA), rheology control additives (thickeners), flame retardants, siccatives, drying agents, skin-preventing agents, corrosion inhibitors, waxes and matting agents.

The type and amount of the additives (C) depend on the intended use of the coatings produced using the process according to the invention.

If the dual-cure coating material to be used according to the invention is used to produce solid-color top coats or basecoats, it contains color and / or effect pigments (C) and, if appropriate, opaque fillers. If the dual-cure coating material to be used according to the invention is used for the production of clearcoats, these additives (C) are naturally not contained therein.

Examples of suitable effect pigments (C) are platelet pigments such as commercially available aluminum bronzes, aluminum bronzes chromated according to DE-A-36 36 183, and commercially available stainless steel bronzes as well as non-metallic effect pigments, such as pearlescent or interference pigments. In addition, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 176, "Effect Pigments" and pages 380 and 381 "Metal Oxide Mica Pigments" to "Metal Pigments". Examples of suitable inorganic color pigments (C) are titanium dioxide, iron oxides, Sicotrans yellow and carbon black. Examples of suitable organic coloring pigments (C) are thioindigo pigments indanthrene blue, chromophot, irgazine orange and heliogen green. In addition, Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 180 and 181, "iron blue pigments" to "iron oxide black", pages 451 to 453 "pigments" to "pigment volume concentration", page 563 "thioindigo pigments" and See page 567 “Titanium dioxide pigments”.

Examples of suitable organic and inorganic fillers (C) are chalk, calcium sulfates, barium sulfate, silicates such as talc or kaolin, silicas, oxides such as aluminum hydroxide or magnesium hydroxide or organic fillers such as textile fibers, cellulose fibers, polyethylene fibers or wood flour. In addition, reference is made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, 1998, pages 250 ff., "Füllstoffe".

These pigments and fillers (C) can also be incorporated into the dual-cure coating materials using pigment pastes. the hydroxyl-containing (meth) acrylate copolymers (B) described above are suitable.

Examples of suitable binders (C) are thermally curable hydroxyl-containing or curable with actinic radiation, linear and / or branched and or block-like, comb-like and / or randomly constructed poly (mefh) acrylates or acrylate copolymers, polyesters, alkyds, polyurethanes, acrylated polyurethanes, acrylated polyesters Polylactones, polycarbonates, polyethers, epoxy resin-amine adducts, (meth) acrylate diols, partially saponified polyvinyl esters or polyureas or (me) acrylic functional (meth) acrylate copolymers curable with actinic radiation. Polyether acrylates, polyester acrylates, unsaturated polyesters, epoxy acrylates, urethane acrylates, Amino acrylates, melamine acrylates, silicone acrylates and the corresponding methacrylates.

Examples of suitable thermally curable reactive diluents (C) are positionally isomeric diethyloctanediols or hydroxyl group-containing hyperbranched compounds or dendrimers.

Examples of suitable reactive thinners (C) curable with actinic radiation are those described in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, on page 491 under the keyword “reactive diluents”.

Examples of suitable crosslinking agents (C) for thermal curing are amino resins, compounds or resins containing anhydride groups, compounds or resins containing epoxy groups,

Tris (alkoxycarbonylamino) triazines, compounds or resins containing carbonate groups, blocked and / or unblocked polyisocyanates, beta-hydroxyalkylamides and compounds with on average at least two groups capable of transesterification, for example reaction products of diesters of malonic acid and polyisocyanates or of esters and partial esters of polyhydric alcohols of malonic acid Monoisocyanates as described in the Exxropaean patent EP-A-0 596 460.

Examples of suitable low-boiling organic solvents (C) and high-boiling organic solvents (C) (“long solvents”) are ketones such as methyl ethyl ketone or methyl isobutyl ketone, esters such as ethyl acetate or butyl acetate, ethers such as dibutyl ether or ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, Butylene glycol or

Dibutylene glycol dimethyl, diethyl or dibutyl ether, N-methylpyrrolidone or Xylenes or mixtures of aromatic hydrocarbons such as Solvent Naphtha® or Solvesso®.

Examples of suitable light stabilizers (C) are HALS compounds, benzotriazoles or oxalanilides.

Examples of suitable thermolabile free radical initiators (C) are the initiators described above, which are used in the preparation of the hydroxyl-containing (metha) acrylate copolymers (B).

Examples of suitable catalysts (C) for crosslinking are dibutyltin dilaurate, lifhium decanoate or zinc octoate;

An example of a suitable deaerating agent (C) is diazadicycloundecane;

Examples of suitable emulsifiers (C) are nonionic emulsifiers, such as alkoxylated alkanols and polyols, phenols and alkylphenols or anionic emulsifiers such as alkali metal salts or ammonium salts of alkane carboxylic acids, alkane sulfonic acids, and sulfonic acids of alkoxylated alkanols and polyols, phenols and alkylphenols.

Examples of suitable wetting agents (C) are siloxanes, fluorine-containing compounds, carboxylic acid half-esters, phosphoric acid esters, polyacrylic acids and their copolymers or polyurethanes.

An example of a suitable adhesion promoter (C) is tricyclodecanedimethanol;

Examples of suitable film-forming aids (C) are cellulose derivatives. Examples of suitable transparent fillers (C) are those based on silicon dioxide, aluminum oxide or zirconium oxide; In addition, reference is made to the Römpp Lexicon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, 1998, pages 250 to 252.

Examples of suitable Sag control agents (C) are ureas, modified ureas and or silicas, as described, for example, in references EP-A-192 304, DE-A-23 59 923, DE-A-18 05 693, WO 94/22968 , DE-C-27 51 761, WO 97/12945 or "färbe + lack", 11/1992, pages 829 ff.

Examples of suitable rheology-controlling additives (C) are those known from the patents WO 94/22968, EP-A-0 276 501, EP-A-0 249 201 or WO 97/12945; crosslinked polymeric microparticles, such as are disclosed, for example, in EP-A-0 008 127; inorganic layered silicates such as aluminum magnesium silicates, sodium magnesium and

Montmorillonite type sodium magnesium fluorine lithium layered silicates; Silicas such as aerosils; or synthetic polymers with ionic and / or associative groups such as polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid, polyvinyl pyrrolidone, styrene-maleic anhydride or ethylene-maleic anhydride copolymers and their derivatives or hydrophobically modified ethoxylated urethanes or polyacrylates;

An example of a suitable matting agent (C) is magnesix stearate.

Further examples of the additives (C) listed above and examples of suitable UV absorbers, radical scavengers, leveling agents,

Flame retardants, siccatives, drying agents, skin preventives, corrosion inhibitors and waxes (C) are described in the textbook »Paint Additives« by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998.

Water can also be used as additive (C) if aqueous dual-cure coating materials are to be produced.

The additives (C) are used in customary and known, effective amounts.

The production of the dual-cure substance mixtures according to the invention has no special features, but is carried out in a customary and known manner by mixing the constituents (A), (B) and (C) described above in suitable mixing units such as stirred kettles, dissolvers, agitator mills or extruders the methods suitable for the production of the respective dual cure substance mixtures according to the invention.

Since the dual-cure coating material to be used according to the invention is a two-component system in which the component (A) must be stored separately from the component (B) until it is used because of its high reactivity, the components ( A) and (C) a component I and from component (A) and optionally an additive which is inert to isocyanate groups (C), in particular an organic solvent (C), a component II. Components I and II are then combined shortly before the dual-cure coating materials are used.

The coatings produced with the aid of the method according to the invention, in particular the single- and multi-layer clearcoats and color and / or effect coatings, are of the highest optical quality in terms of color, effect, gloss and DOI (distinctiveness of the reflected image), have a smooth, structureless, hard, flexible and scratch-resistant surface, are odorless and weather, chemical and etch resistant, do not yellow and show no cracking and delamination of the layers.

The coated or unprimed substrates coated with these coatings therefore have a particularly long service life and a particularly high utility value, which makes them technically and economically particularly attractive for manufacturers, users and end users.

Examples and comparative tests

Examples 1 to 3 and comparative experiments VI and V2

The production of clearcoats and clearcoats by the process according to the invention (Examples 1 to 3) and the process according to the invention (comparative experiments VI and V2)

For Examples 1 to 3, the constituents (A), (B) and (C) given in Table 1 and for the comparative experiments VI and V2, the constituents (A) and (C) given in Table 1 and those not according to the invention to be used mixed together. The mixing ratios were chosen so that a molar ratio of hydroxyl groups to isocyanate groups of 1.43 resulted.

Table 1: The composition of the clearcoats to be used according to the invention (Examples 1 to 3 and of the clearcoats not to be used according to the invention (comparative experiments VI and V2)

Example and

Comparison attempt VI V2 1 2 3

Roskydal® UA 2337 ^a) 11.6 8.2985 4.838 5.272 5.272

Desmophen® RD 181 ^b) 11.2

Uralac® AN 623 ^c) - 12.86 -

Uracron® CY 467 ^d) - - 19.248 -

Uracron® XP 476 ^e) - - - 16.36 -

Desmophen® A 450 °. , , , 19.091

Butyl acetate 11.2 12.853 19.248 15.454 19.091

Solvent mixture ^s) 65.98 65.973 56.658 62.905 56.538

Dibutyltin dilaurate ^h) 0.02 0.014 0.008 0.009 0.008

a) acrylated polyisocyanate from Bayer AG; b) hydroxyl-containing polyester from Bayer AG;

c) hydroxyl-containing alkyd resin from DSM;

d) hydroxyl-containing polyacrylate resin from DSM;

e) hydroxyl group-containing polyacrylate resin from DSM;

f) polyacrylate resin from Bayer AG containing hydroxyl groups;

g) methyl ethyl ketone / methyl isobutyl ketone / butyl acetate / ethyl acetate / xylene in a mixing ratio of 20/10/10/10/15/3;

h) 1% in xylene.

The clear coats described above were applied to glass plates using a 200 μm box doctor blade. After an evaporation time of 10 minutes, they are physically pre-dried in a forced air dryer. The subsequent curing with UV radiation was carried out with two CK lamps (80 W / cm) at a speed of 5.5 m / min. The resulting clearcoats were allowed to cool for ten minutes. Then their pendulum hardness was determined according to König (DLN 53157; Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart. New York, "Pendulum damping test", page 436). The test results can be found in Table 2.

Table 2: The König pendulum hardness that in the procedure according to the invention (Examples 1 to 3) and that in not Procedure according to the invention (comparative experiments VI and V2) produced clearcoats

Example and comparison test: VI V2 1 2 3

Pendulum hardness (s): - - 114.8 112 105

The test results make it clear that only the dual-cure clearcoats to be used according to the invention can deliver hard clearcoats.

Claims

Process for the production of coatings from coating materials curable thermally and with actinic radiation

1. Process for the production of coatings from coating materials curable theoretically and with actinic radiation on primed and unprimed substrates

(1) Application of at least one thermally and with actinic

Jet curable coating material onto the primed or unprimed substrate or onto a basecoat layer thereon, whereby a layer results from the coating material, and

(2) curing the layer with heat and current radiation,

using a coating material consisting of

A) at least one compound that is statistical

At least one free isocyanate group xmd at least one bond that can be activated with actinic radiation xmg and molecule

B) at least one hydroxyl-containing (meth) acrylate copolymer

or from at least one component (A). at least one component (B) and C) at least one additive selected from the group consisting of color and / or effect pigments, organic and inorganic, transparent or opaque fillers, nanoparticles, oligomeric and polymeric binders, thermally and / or reactive diluents curable with actinic radiation, crosslinking agents for the thermal curing, low and high-boiling organic solvents ("long solvents"), water, UV absorbers, light stabilizers, radical scavengers, thermolabile free radical initiators, catalysts for thermal crosslinking, deaerators,

Slip additives, polymerization inhibitors, defoamers, emulsifiers, wetting xmd detergents, adhesion promoters, flow control agents, film-forming aids, sag control agents (SCA), rheology-controlling additives (thickeners), flame retardants, siccatives, drying agents,

Anti-skinning agents, corrosion inhibitors, waxes xmd matting agents;

consists.

2. The method according to claim 1, characterized in that UV radiation is used as actinic radiation.

3. The method according to claim 1 or 2, characterized in that as activatable with actinic bonds carbon-hydrogen

Single bonds or carbon-carbon, carbon-oxygen, carbon-nitrogen, carbon-phosphorus or carbon-silicon single bonds or double bonds can be used.

4. The method according to claim 3, characterized in that one uses carbon-carbon double bonds.

5. The method according to claim 4, characterized in that (meth) acrylate, ethacrylate, crotonate, cinnamate, vinyl ether,

Vinyl ester, dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, AUyl or butenyl groups; Dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, AUyl or butenyl ether groups or dicyclopentadienyl, norbomenyl, isoprenyl, isopropenyl, AUyl or butenyl ester groups are used.

6. The method according to claim 5, characterized in that one uses acrylate groups.

7. The method according to any one of claims 1 to 6, characterized in that the coatings are single and multi-layer clearcoats and coloring and / or effect coatings.

8. The method according to any one of claims 1 to 7, characterized in that the basecoat is made of a dual-cure coating material.

9. The method according to any one of claims 1 to 8, characterized in that the components (A) and (B) or (B) and (C) and (A) in one

Quantity ratio (B): (A) or [(B) + (C)]: (A) are used so that the molar ratio of hydroxyl groups to isocyanate groups is 3: 1 to 1: 2.