EP0435236A1

EP0435236A1 - Coating systems for providing surfaces with chromatic decorative effects in relief

Info

Publication number: EP0435236A1
Application number: EP90125438A
Authority: EP
Inventors: Giorgio Vernizzi; Peppino Raffellini; Lucio Trevisan; Milco Ferreti
Original assignee: Oece Industrie Chimiche SpA
Current assignee: Oece Industrie Chimiche SpA
Priority date: 1989-12-29
Filing date: 1990-12-24
Publication date: 1991-07-03
Also published as: CA2033378A1; IT8922876A0; IT1237547B; IT8922876A1

Abstract

A process is described for obtaining coated surfaces with chromatic decorative effects in relief, by applying simultaneously or in quick succession to the surface to be coated at least two different coatings of which the physico-chemical characteristics are so different as to totally prevent or considerably limit diffusion of the coatings into each other.

Description

State of the art

The following method is normally used to obtain coated objects with special chromatic effects: a coating layer is spread over the surface to be coated, the system is cross-linked and/or dried and a second coating layer different from the first is then spread over the dried coated surface, the cross-linking and/or drying operation being then repeated to obtain the desired effect. In this manner, coated surfaces with a very wide range of polychromatic effects can be prepared industrially.
It is not known to be able to obtain such polychromatic decorative effects, including relief effects, by the simultaneous or quick-succession application of two or more different coatings before the initially applied coating has dried.

Description of the invention

A process constituting one aspect of the invention has been discovered which enables coated surfaces with chromatic decorative effects in relief, to be obtained by applying at least two different coatings to the surface. These different coatings are applied simultaneously or in quick succession, within 1 to 5 seconds. In this latter case the successive coatings are applied on the first coating before this has dried (wet on wet).
The essential condition to enable the process of the invention to be effected is that the coatings have such physico-chemical characteristics that diffusion of the coatings into each other is totally prevented or at least considerably limited.
A further aspect of the invention is therefore represented by combinations of coatings which do not diffuse substantially into each other and which when spread simultaneously or in quick succession over the object to be coated give rise to chromatic decorative effects in relief.
A further aspect of the invention is represented by the coated objects with chromatic decorative effects in relief obtained by using the aforesaid coatings and process.
To prevent mutual diffusion, the constituent coatings of the coating systems according to the invention must satisfy well defined requirements.
An essential requirement is incompatibility of the constituent coatings of the system. This occurs for example if one of the coatings is a physically driable coating or an unsaturated polyester resin-based coating and the other a water-based coating.
If the coatings are compatible, mutual diffusion can be prevented by special additives which produce substantial differences in the viscosity and/or surface tension and/or specific gravity of the coatings, so making them incompatible. The differences in said physical properties produce interaction between the two coatings to prevent their diffusion, by which particular decorative effects in relief are produced, with a wide range of chromatic variations.
Additives which induce substantial viscosity differences are for example micronized silicas of Aerosil (Degussa) type, cellulose acetobutyrates of CAB (Eastman Kodak) type, polysaccharides and cellulose derivatives of ethylcellulose and carboxymethylcellulose (Hercules) type, montmorillonites of Kronos (NL Chemicals) type, vinyl and acrylic polymers and copolymers of VAGH (Union Carbide) type.
Additives which induce substantial surface tension differences are for example silicone oils of Baysilone A (Bayer) type, methylpolysiloxanes of Tego Wet (Goldschmidt) type, acrylic polymers of Madaflow (Monsanto) type, fluoroderivatives of F.C. (3 Emme) type, oxyethylated surfactants of Etilon (Henkel) type, etc.
The required substantial difference in specific gravity can be induced by adding suitable fillers to one of the coatings. Even a different quantity of different pigments in the coatings can result in a specific gravity difference such as to prevent mutual diffusion of the coatings.
In addition to the already stated decorative effects of high aesthetic merit, the advantages of the process of the invention compared with processes of the known art are the obtaining of a surface with chromatic structures by the application of a smaller number of coats, a higher yield and a faster coating cycle as only one drying stage is required instead of two or more, with consequent productivity increase; the possibility of embellishing supports made of common material such as fibre or chipboard panels of waste wooden material; and the possibility of personalizing decorative effects by setting selected applicational parameters.
The coating systems of the invention consist of combinations of coatings, each chosen from: polyurethane coatings comprising two components (to be mixed together at the moment of use), coatings based on binders with ethylenic unsaturations, physically driable single-component coatings and coatings in the form of aqueous solutions, dispersions or emulsions.
As stated, the constituent coatings of each coating system can be either of different type and thus incompatible (such a solvent-based coating and a water-based coating) or of the same type. In this latter case they must contain additives which induce a substantial difference between the coatings in terms of their surface tension and/or density and/or viscosity, to produce the interactions necessary to prevent diffusion of one coating into another.
In two-component polyurethane coatings, the hydroxyl component has a dry residue of between 20 and 80% and consists of a solution of resins with mobile hydrogens such as saturated polyester, polyol, saturated acrylic and medium-short oil alkyd resins, hydroxylated vinyl polymers, cellulose derivatives etc., dissolved in organic solvents chosen from ethyl, butyl, isobutyl, methoxypropyl or ethoxypropyl acetates, ketones such as methylethylketone, acetone, cyclohexanone, methylisobutylketone, and aromatic solvents such as toluene and xylenes. Organic and inorganic pigments of various type and colour such as titanium dioxide, carbon black, phthalocyanine, iron oxides etc. or soluble colorants and dyes can be added to these solutions, as, if required, fillers such as calcium carbonate, kaolin, silica, talc, zinc stearate, waxes etc., and surface additives such as low molecular weight silicone oils, acrylic polymers, surfactants etc.
The isocyanic component of said two-component polyurethane coatings consists of solutions of polyisocyanates, isocyanic oligomers and prepolymers, with dry residues between 10 and 95%, dissolved in mixtures of anhydrous solvents such as acetates, ketones, aromatics and glycolether acetates similar to those described for the hydroxyl component.
The coatings based on binders with ethylenic unsaturations, in which the filming process takes place by radical reactions activated by redox systems and/or by U.V-visible radiation have a dry residue of between 30 and 95% and consist of unsaturated polyester, polyester acrylate, epoxyacrylate, urethaneacrylate, acrylic, vinylic or siliconacrylate resins; reactive unsaturated monomers of various kinds such as styrene, hexanedioldiacrylate, TPGDA, TMPDA, N-vinylpyrrolidone, vinylacetate, trimethylolpropane-diallylether etc. with possible addition of organic solvents chosen from those indicated heretofore for the two-component polyurethane coatings. Also present are pigments, fillers and surface additives similar to those indicated heretofore for the polyurethane resins; and photoinitiators containing the benzoyl group, which may be substituted; accelerators formed from derivatives or organic salts of transition metals such as cobalt, chromium, manganese etc.
If the filming process is activated by redox systems possibly associated with U.V.-visible radiation, organic peroxides such as cyclohexanoneperoxide, methylethylketoneperoxide, benzoylperoxide, acetylacetoneperoxide, cumenehydroperoxide, peresters etc. are added at the moment of use. Alternatively, instead of being added to the coatings in question, said peroxides can be dissolved in a solution of nitrocellulose polymer to be spread over the surface to be coated before the constituent coatings of the coating system according to the invention are applied (either simultaneously or in quick succession).
The physically driable single-component coatings have a dry residue of between 5 and 70% and consist of vinyl, acrylic, polyurethane, nitrocellulose, polyvinylbutyral etc. polymers, dissolved in organic solvents such as ketones, acetates, aromatics, alcohols, glycolether esters; they can also contain pigments, fillers and surface additives similar to those defined initially for the two-component polyurethane coatings.
The coatings formed from aqueous solutions, dispersions or emulsions have a dry residue of between 10 and 80% and consist of acrylic, acrylourethane, vinyl etc. resins dissolved, emulsified or dispersed in water, and in addition to pigments, fillers and surface additives already defined for the other coatings, they can contain small quantities of plasticizer and/or coalescent agents. The filming process for said coatings, which occurs by evaporation of the water, can be supplemented by reactions on the carboxyl and/or hydroxyl functions present by particular cross-linking agents, in accordance with known methods.
The constituent coatings of the coating systems according to the invention are applied either simultaneously or in quick succession, within 1 to 5 seconds, using for example curtain coaters with two heads positioned next to each other or at a determined distance apart, or double feed sprayers with their nozzles positioned next to each other or at a determined distance apart.
A particular apparatus suitable for the purpose is described in a patent application filed by the applicant simultaneously with the present application. This apparatus, which according to the effect to be obtained can be positioned next to a normal curtain coater head or at a determined distance upstream or downstream from it, which we have called "mechanical brush", is provided with nozzles which allow controlled delivery of the coating either discontinuously, in intermittent or droplet form, or as a continuous flow, both methods being adjustable in terms of intensity and frequency.
The essential elements of this apparatus are shown in Figures 1 to 3. Figure 1 is a view from the top of part of the tank containing the coating product; Figure 2 is a section on the line A-A and Figure 3 is a section on the line B-B.
The apparatus comprises: a tank 1 of parallelepiped shape for containing the coating product and housing in threaded seats in its base various delivery heads 2 on which dispensing rods 3 act to distribute the coating over the surface to be coated. The dispensing rods are operated by rockers and a camshaft 4 driven by a variable speed motor.
The delivery machine can be incorporated into an independent unit or be positioned next to, in front of or behind the head of a conventional curtain coater.
Varying the speed of rotation of the camshaft varies the time between the opening periods of each delivery head.
As the speed of advancement of the material to be coated and the camshaft r.p.m. are interdependent in terms of obtaining droplets at a constant rate, it follows that a wide range of droplet rates can be obtained by varying the speed of advancement of the material to be coated and/or the camshaft r.p.m.
The position of the cams on the camshaft can be adjusted at will to vary the rate of droplet delivery by one delivery head compared with the others.
A special camshaft is used to obtain intermittent lines. Such intermittent lines can also be adjusted in terms of line length, width and gap length.
A "continuous line delivery device" can be mounted on the upper heads of the dispensing rods to halt the camshaft and so obtain continuous delivery by the delivery heads. Adjustment is again possible in this case to obtain thicker or thinner lines. Further details of this apparatus are available from the industrial invention patent application filed by the applicant simultaneously with the present application.
This apparatus has proved particularly suitable for implementing the process of the invention in that with normal known coating application systems (sprayers, rollers, single or multi-head curtain coaters) the possibility for creating variable decorative effects is limited because a continuous film is always obtained. In contrast the "mechanical brush" apparatus enables the coating to be delivered in various rows of droplets, various rows of continuous lines or various rows of intermittent lines, or combinations of these, and the dimensions and arrangement of the droplets and lines can be modified to obtain asymmetric and fantasy patterns and shapes which are always reproducible.
The following non-limiting examples are given to better illustrate the invention.

EXAMPLE 1

The coating system consists of a green unsaturated polyester coating and a grey coating of physically driable type.
The unsaturated polyester coating has the following percentage formulation:
The coating should have a viscosity of about 30-35 seconds (Ford cup 4. ASTM-1800-82 method). If necessary, this value is attained by adding ethyl acetate.
The physically driable single component coating has the following percentage formulation:
The viscosity should be 15-20 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
10 g/m² of a solution containing 15% of methylethylketone peroxide and 8% of a nitrocellulose polymer of Hacolor (Hagedorn) type dissolved in ethylacetate are applied by roller to fibre panels treated with melamine paper.
They are heated to 45-50°C for 50 seconds by hot air circulation after which the green polyester coating is applied by a curtain coater in a quantity of about 120 g/m².
After a second, using the mechanical brush of Figures 1 to 3, the grey single-component coating is applied by dripping, in a quantity of about 35 g/m².
The thus treated panels are subjected to the following drying cycle:

15 minutes in an oven at 45-50°C by hot air circulation
15 minutes of U.V. irradiation by high power lamps (100 W/cm)
60 minutes at ambient temperature.

A glossy film properly hardened and adhering to the support is obtained, of green colour with grey relief spots the dimensions and frequency of which depend on the state of adjustment of the mechanical brush.
The quality decorative effect obtained is properly reproducible.

EXAMPLE 2

The coating system is the same as described in Example 1, with only the conditions of application with the mechanical brush and the drying cycle being varied.
10 g/m² of a solution containing 15% of methylethylketone peroxide and 8% of a nitrocellulose polymer of Hacolor (Hagedorn) type dissolved in ethylacetate are applied by roller to fibre panels treated with melamine paper.
They are heated to 45-50°C for about 60 seconds by hot air circulation after which the green unsaturated polyester coating is applied by a curtain coater in a quantity of about 120 g/m².
Two seconds later, using the mechanical brush, the grey single-component is applied in the form of continuous lines in a quantity of about 60 g/m².
The thus treated panels are subjected to the following drying cycle:

20 minutes in an oven at 40-50°C by hot air circulation
15 minutes of U.V. irradiation by high power lamps (100 W/cm)
70 minutes at ambient temperature.

A glossy film properly polymerized and adhering to the support is obtained, of green colour with bas-relief lines the dimensions and distance apart of which depend on the state of adjustment of the mechanical brush.
The decorative effect is properly reproducible.

EXAMPLE 3

The coating system consists of two two-component polyurethane coatings.
The first blue polyurethane coating is prepared by mixing together at the moment of use 1 part of component A and 1 part of component B. The two components have the following percentage formulation:
The coating obtained by mixing the two components should have a viscosity of 15-20 seconds (Ford cup 4). If necessary, this value is attained by adding ethylacetate.
The second yellow polyurethane coating is prepared by mixing together at the moment of use 2 parts of the following component A and 1 part of the following component B. These two components have the following percentage formulation:
The coating obtained by mixing the two components should have a viscosity of 25-30 seconds (Ford cup 4). If necessary, this value is attained by adding ethylacetate.
Using the mechanical brush, the first blue polyurethane coating is applied to filler-treated chipboard panels as a rapid series of droplets in a quantity of about 55 g/m². This is immediately followed, two seconds later, by application of the yellow polyurethane coating by a curtain coater in a quantity of about 110 g/².
The thus prepared panels are subjected to the following drying cycle:

5 minutes at ambient temperature with air changes
70 minutes in an oven at 45-50°C with hot air circulation.

A properly polymerized adherent film is obtained, with its surface in the form of small arched regions surrounding large blue openings.
The effect is properly reproducible.

EXAMPLE 4

The coating system consists of the products described in Example 3, but the yellow polyurethane coating has a viscosity of 10-15 seconds (Ford cup 4): it is now applied with two airbrushes.
The two coatings are applied simultaneously to filler-treated chipboard panels, the blue one in a quantity of about 110 g/m², the yellow one in a quantity of 120 g/m².
The thus treated panels are subjected to the following drying cycle:

A properly hardened film adhering to its support is obtained, with a glossy surface having relief graining of irregular design with colours ranging from yellow to blue, and with a considerable green component.

EXAMPLE 5

The coating system consists of a red physically driable coating and a black unsaturated polyester coating.
The physically driable coating has the following percentage formulation:
The viscosity should be 15-25 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
The unsaturated polyester coating has the following percentage formulation:
The viscosity should be 25-30 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
10 g/m² of a solution containing 15% of acetylacetone peroxide and 10% of a nitrocellulose polymer of Norma 34E (Sipe Nobel) type dissolved in ethylacetate are applied by roller to fibre laminate panels.
They are heated to 45-50°C for 65 seconds by hot air circulation, after which about 20 g/m² of the red coating are applied by slow dripping using the mechanical brush, followed, three seconds later, by about 120 g/m² of the black unsaturated polyester coating using a curtain coater.
The thus coated panels are then subjected to the following drying cycle:

10 minutes at 40-50°C by hot air circulation
15 minutes of U.V. irradiation by high power lamps (80-120 W/cm)
45 minutes at ambient temperature.

A film properly polymerized and adhering to the support is obtained, having a black glossy surface with opaque red spots in bas-relief. The decorative effect can be reproduced by keeping all operating conditions unaltered.

EXAMPLE 6

The coating system is the same as in Example 5, whereas the application and drying cycles are varied.
15 g/m² of a solution containing 15% of acetylacetone peroxide and 10% of a nitrocellulose polymer dissolved in ethylacetate are applied to fibre laminated panels.
They are heated to 45-50°C for 65 seconds by hot air circulation, after which about 110 g/m² of the red coating are applied by curtain coater, followed by about 40 g/m² of the black unsaturated polyester coating by rapid dripping using the mechanical brush.
The thus coated panels are then subjected to the following drying cycle:

15 minutes at 40-45°C by hot air circulation
15 minutes of U.V. irradiation by high power lamps (100 W/cm)
70 minutes at ambient temperature.

A glossy film properly polymerized and adhering to the support is obtained, having a red satin-like surface with tangential glossy black relief spots. The effect is properly reproducible.

EXAMPLE 7

The coating consists of a two-component black polyurethane coating and a coating in the form of a white aqueous dispersion.
The polyurethane coating is prepared by mixing together at the moment of use two parts of component A and one part of component B.
The two components have the following percentage composition:
The polyurethane coating obtained by mixing the two components should have a viscosity of about 25-35 seconds (Ford cup 4). If necessary, this value is attained by adding ethylacetate.
The coating in aqueous dispersion form has the following percentage composition:
The viscosity should be 25-35 seconds (Ford cup 4). If necessary, this value is attained by adding water.
The black polyurethane coating is applied in a quantity of 60 g/m² in the form of thin continuous lines with the mechanical brush to chipboard panels treated with melamine paper, and two seconds later the water coating is applied in a quantity of 90 g/m² by curtain coater.
Considerable interaction between the two coatings is noted, with the formation of the decorative effect.
The coated panels are then dried at 45-50°C for 90 minutes by hot air circulation.
In this manner a properly hardened satin-like film is obtained having a black surface with regular white lines in relief, with grey edges. The decorative effect is reproducible.

EXAMPLE 8

The coating system comprises the coatings of Example 7.
Using a two-headed curtain coater, the black polyurethane coating in a quantity of 100 g/m₂ and contemporaneously the water coating in a quantity of 80 g/m² are applied to filler-treated chipboard panels.
The panels are then dried for 90 minutes at 45-50°C by hot air circulation.
In this manner a hard film adhering to its support is obtained, having a black opaque surface with white reliefs of irregular shape.

EXAMPLE 9

The coating system consists of a white coating in aqueous dispersion form and a blue physically driable coating.
The aqueous dispersion coating has the following percentage composition:
The viscosity of the coating should be 15-25 seconds (Ford cup 4).
If necessary, this value is attained by adding water.
The viscosity should be 15-25 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
The aqueous coating is applied in a quantity of about 25 g/m² by slow dripping with the mechanical brush to chipboard panels treated with melamine paper, followed, two seconds later, by application of the blue single component in a quantity of 100 g/m² by curtain coater. The coated panels are dried for 90 minutes at 45-50°C in an oven with hot air circulation.
In this manner a hard film adhering to the support is obtained, having a blue satin-like surface with light blue round spots in bas relief. The effect is properly controllable and reproducible.

EXAMPLE 10

The system is the same as in Example 9.
The aqueous coating is applied in a quantity of 100 g/m² by curtain coater to filler-filled fibre panels, followed, three seconds later, by application of the physically driable coating in a quantity of 30 g/m² by slow dripping with the mechanical brush.
The panels are then dried for 90 minutes at 45-50°C by hot air circulation.
In this manner a hard film adhering to the support is obtained, having a white opaque surface with regular blue spots having a light blue halo. The decorative effect is regular and properly repeatable.

EXAMPLE 11

The coating system comprises two aqueous coatings.
The first coating has the following percentage composition:
The viscosity of the coating prepared in this manner is adjusted if necessary to 20-25 seconds (Ford 4 cup) by adding water.
The second coating has the following percentage composition:
The coating viscosity should be 30-35 seconds (Ford cup 4). If necessary, this value is attained by adding water.
The first coating is applied in a quantity of about 130 g/m² by curtain coater to filler-filled fibre panels, followed, three seconds later, by application of the second coating in a quantity of 25 g/m² by slow dripping with the mechanical brush.
The thus treated panels are then dried for 80 minutes at 45-50°C in an oven with hot air circulation.
In this manner a hard film adhering to the support is obtained, having a white surface with light blue shaded nucleate drops (in the form of cells) having a blue core with pearly reflections.

EXAMPLE 12

The coating system consists of the two aqueous coatings described in Example 11.
The first white coating is applied in a quantity of about 130 g/m² by curtain coater to MDF panels treated with melamine paper, followed, one second later, by application of the second blue coating in a quantity of about 40 g/m² by slow dripping with the mechanical brush.
The coated panels are dried at 50 C in an oven with hot air circulation for 80 minutes.
A hard film adhering to the support is obtained, having a white surface with large blue pearlescent cores in relief surrounded by blue haloes also in relief.

EXAMPLE 13

The coating system consists of a green unsaturated polyester coating, a grey physically driable coating and a white coating in aqueous dispersion form.
The unsaturated polyester coating has the following percentage formulation:
The coating should have a viscosity of about 30-35 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
The grey physically driable coating has the following percentage formulation:
The viscosity should be 15-20 seconds (Ford cup 4). If necessary, this value is attained by adding ethyl acetate.
The white coating in aqueous dispersion form has the following percentage formulation:
The viscosity of the coating prepared in this manner is adjusted if necessary to 20-25 seconds (Ford 4 cup) by adding water.
10 g/m² of a solution containing 15% of cyclohexanone peroxide and 10% of a nitrocellulose polymer of Hacolor (Hagedorn) type dissolved in ethylacetate are applied by roller to filler-treated chipboard panels.
They are heated to 45-50°C for 50 seconds by hot air circulation after which the green unsaturated polyester coating is applied with the first head of the curtain coater in a quantity of about 110 g/m²; one second later, the grey single-component coating is applied by dripping using the mechanical brush, in a quantity of 20 g/m² and contemporaneously the white coating in aqueous dispersion form is applied with the second head of the curtain coater in a quantity of 70 g/m².
The thus treated panels are dried in the following manner:
5 minutes at ambient temperature with air circulation (flash period) 70 minutes in an oven at 45-50°C with hot air circulation.
In this manner a properly hardened film adhering to the support is obtained, of green colour with grey and white spots in relief. The effect is reproducible.

Claims

A process for obtaining coated surfaces with chromatic decorative effects in relief, characterised by applying simultaneously or within 1 to 5 seconds to the surface to be coated at least two different coatings which do not diffuse into each other.
A process as claimed in claim 1, wherein each of the different coatings is chosen from: polyurethane coatings consisting of two components to be mixed together at the moment of use, coatings based on binders with ethylenic unsaturations, physically driable coatings and coatings in solution, dispersion or aqueous emulsion form.
A process as claimed in claims 1 and 2, characterised in that one coating is applied to the surfaces to be coated, and before this coating has gelled a second different coating which does not diffuse into the first is applied.
A process as claimed in claim 3, wherein one of the coatings is a coating based on binders with ethylenic unsaturations and the other is a physically driable coating.
A process as claimed in claim 3, wherein the coatings are two-component polyurethane coatings having different viscosities.
A process as claimed in claim 3, wherein one of the coatings is a two-component polyurethane coating and the other is a coating of aqueous dispersion type.
A process as claimed in claim 3, wherein one of the coatings is a coating of aqueous dispersion type and the other is a physically driable coating.
A process as claimed in claim 3, wherein the coatings are aqueous coatings having different viscosities.
A process as claimed in claims 1 and 2, characterised in that one coating is applied to the surfaces to be coated, and before this coating has gelled a second and a third coating which do not diffuse either into each other or into the first coating are applied.
A process as claimed in claim 9, characterised in that one of the coatings is an unsaturated polyester coating, another is a physically driable coating and the third is a coating of aqueous dispersion form.
A process as claimed in claims 3 and 9, characterised in that one of the coatings comprises unsaturated polyester resins cross-linkable by redox or U.V-redox systems, and the surface to be coated is pretreated with a solution of a physically driable resin and a peroxide.
Coating systems able to provide coated surfaces having chromatic decorative effects, comprising at least two different coatings which do not diffuse into each other.
Coating systems as claimed in claim 12, wherein each of the different coatings is chosen from: polyurethane coatings in the form of two components to be mixed together at the moment of use, coatings based on binders with ethylenic unsaturations, physically driable coatings and coatings in solution, dispersion or aqueous emulsion form.
Coating systems as claimed in claim 13, comprising two different coatings.
Coating systems as claimed in claim 13, comprising three different coatings.
Coating systems as claimed in claim 14, wherein one of the coatings is a coating based on binders with ethylenic unsaturations, and the other is a physically driable coating.
Coating systems as claimed in claim 14, wherein the coatings are two-component polyurethane coatings having different viscosities.
Coating systems as claimed in claim 14, wherein one of the coatings is a two-component polyurethane coating and the other is a coating of aqueous dispersion type.
Coating systems as claimed in claim 14, wherein one of the coatings is a coating of aqueous dispersion type and the other is a physically driable coating.
Coating systems as claimed in claim 14, wherein the coatings are aqueous coatings having different viscosities.
Coating systems as claimed in claim 14, wherein one of the coatings is an unsaturated polyester coating, another is a physically driable coating and the third is a coating of aqueous dispersion form.
Coated articles with chromatic decorative effects, obtained by the process claimed in claims 1 to 11 and by the coating systems claimed in claims 12 to 21.