Paintable and Painted Materials With Structured Surfaces

Abstract

The invention relates to a paintable material having a structured surface made of plastic containing amino groups, wherein at least a part of the amino groups on the structured surface has been functionalized covalently with vinyl groups by grafting a functionalizing reagent. Painted materials having structured paint surfaces can be obtained from these paintable material, wherein the invention also relates to said painted materials as well as to their production methods. The invention further relates to the use of a vinyl functionalization as a substitute for a primer layer or foundation in the painting of structured surfaces made of plastic containing amino groups with radiation-curing paints.

Claims

1. A paintable material having a surface made of a plastic containing amino groups, wherein the surface is structured and that at least a part of the amino groups on the structured surface of the plastic containing amino groups has been functionalized covalently with vinyl groups by grafting a functionalizing reagent.

2. The paintable material according to claim 1, wherein the functionalizing reagent has at least one vinyl group and at least one group reactive towards the amino groups of the plastic containing amino groups.

3. The paintable material according to claim 1, wherein the functionalizing reagent has a molecular weight of 90 to 2000, preferably of 95 to 1100, and more preferably of 95 to 600.

4. The paintable material according to claim 3, wherein the further group in the functionalizing reagent, which is reactive towards the amino groups of the plastic containing amino groups, is selected from the group consisting of epoxides, anhydrides, acid chlorides, acid azides, sulfonyl chlorides, ketones, aldehydes, carboxylic acids, esters, in particular N-hydroxysuccinimide esters, imido esters, or carbonates, carbodiimides, isocyanates, isothiocyanates, alkyl halides, aryl halides, alkynes and vinyl groups such as, for example, acrylate, methacrylate, or acrylamide.

5. The paintable material according to claim 4, wherein the further group in the functionalizing reagent, which is reactive towards the amino groups of the plastic containing amino groups, is also a vinyl group.

6. The paintable material according to claim 5, wherein the grafting comprises applying the functionalizing reagent in an amount of less than 5 g/m.sup.2, in particular less than 2 g/m.sup.2 or less than 1 g/m.sup.2 to the structured surface of the plastic containing amino groups, and subsequently heating or irradiating with UV or electron beams.

7. The paintable material according to claim 4, wherein the functionalizing reagent is selected from the group consisting of di-, tri-, tetra-, penta- or even higher functional acrylates, methacrylates, vinyl ethers and allyl ethers, wherein the functionalizing reagent may in particular be selected from the group consisting of trimethylolpropane triacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, hexanediol diacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate neopentyl glycol diacrylate, and propoxylated or ethoxylated variants of these compounds, polyalkylene glycol diacrylates, in particular polyethylene glycol diacrylates, divinyl ethers, in particular diethylene glycol divinyl ethers, triethylene glycol divinyl ethers or cyclohexanedimethanol divinyl ethers, and diallyl ethers.

8. The paintable material according to claim 7, wherein the vinyl groups in the material surface and/or in the functionalizing reagent are selected from the group consisting of acrylates, methacrylates, vinyl ethers, allyl ethers and vinyl aromatic compounds, the latter being selected in particular from styrene, C.sub.1-4-alkyl-substituted styrene, stilbene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, tert-butoxystyrene and vinylpyridine.

9. The paintable material according to claim 8, wherein the plastic containing amino groups is selected from the group consisting of aminoplast resins, aminopolysiloxanes, polyvinylamines, polyalkyleneimines, aminoepoxide resins, and polyurethanes having terminal amino groups.

10. The paintable material according to claim 9, wherein the plastic containing amino groups is an aminoplast resin, in particular a melamine-formaldehyde resin or a melamine-urea-formaldehyde resin.

11. The paintable material according to claim 10, wherein the material is a sheet-shaped or board-shaped material, in particular a wooden material board; a carrier coated with a plastic containing amino groups; an impregnated or coated paper or a laminate containing one or more impregnated or coated papers, in particular a DPL, HPL or CPL, a compact board or another layered material.

12. A painted material having a structured paint surface which can be obtained by: (a) providing a paintable material according to claim 11, (b) applying a layer of a radiation-curing paint to the vinyl group-modified, structured plastic surface of the material, (c) radiation-curing the paint layer.

13. The painted material according to claim 12, wherein the radiation-curing paint is a topcoat and the painted material does not contain a paint primer or undercoat layer.

14. The painted material according to claim 12, wherein the total amount of radiation-curing paint applied to the plastic surface is less than 20 g/m.sup.2, in particular less than 15 g/m.sup.2 or less than 10 g/m.sup.2.

15. The painted material according to claim 12, wherein the paint layer is an excimer-cured paint layer and/or has a gloss value of less than 10, preferably less than 5, in each case measured according to EN ISO 2813 with the 60° geometry.

16. The paintable material according to claim 11 or respectively a painted material, wherein the structured material surface or respectively the structured paint surface has an Rz value measured according to DIN EN ISO 4287 of at least 10 .Math.m, in particular at least 15 .Math.m or at least 20 .Math.m.

17. The paintable material or respectively the painted material according to claim 16, wherein the surface structure of the structured material surface or respectively the structured paint surface is a decorative structure originally produced by embossing, lamination, calendering, etching, lasering or printing, which in particular represents the surface structure of wood, natural stone, artificial stone, ceramics, metal, mosaics, floorboards, tiles, joints or another decorative structure visible to the naked eye.

18. A method of producing a paintable material according to claim 11 comprising the following steps: c) providing a material having a structured surface made of a plastic containing amino groups, d) covalent functionalization of the structured surface with vinyl groups by (i) contacting the structured surface with a functionalizing reagent having at least one vinyl group and at least one further group reactive towards the amino groups of the plastic containing amino groups, and (ii) performing a chemical reaction to generate a covalent bond between the second reactive group of the functionalizing reagent and an amino group on the structured surface of the plastic containing amino groups, thereby obtaining a structured surface covalently modified with vinyl groups.

19. The method of producing a painted material having a structured paint surface according to claim 17, comprising the following steps: a) performing a process, or providing a paintable material, b) applying a layer of radiation-curing paint to the structured surface of the material functionalized with vinyl groups, c) radiation curing of the paint layer.

20. The use of a vinyl functionalization as a substitute for a primer layer or undercoat in the painting of structured surfaces of plastics containing amino groups with radiation-curing paints.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] FIG. 1: shows a paintable or painted material according to the invention, which is board-shaped and whose surface has a structuring that imitates a wood grain,

[0112] FIG. 2: shows cross-sections through various paintable board-shaped materials according to the invention to illustrate the structure of these materials and their surface layers, with FIG. 2a showing a laminate, FIG. 2b a layered material and FIG. 2c a wooden material,

[0113] FIG. 3: shows a schematic detailed view of the material surface made from a plastic containing amino groups, showing how an amino group present there can react with the functionalizing reagent according to the invention to result in a vinyl functionalization of the material surface,

[0114] FIG. 4: shows cross-sections through various board-shaped materials painted according to the invention, wherein the materials in question are those shown in FIG. 2, the surface of which has been functionalized according to the invention and then painted with a radiation-curing paint,

[0115] FIG. 5: shows schematic representations of the structured material surface before and after painting and, if necessary, functionalization, FIG. 5a showing a structured material surface before any functionalization or painting, FIG. 5b showing a surface primed or respectively undercoated according to the state of the art and then painted, FIG. 5c showing a paintable material surface functionalized with vinyl groups according to the invention, and FIG. 5d showing a functionalized surface after painting as shown in FIG. 5c,

[0116] FIG. 6: shows a schematic representation of the production process for the paintable or respectively painted material according to the invention.

[0117] FIG. 7: shows an example profile to explain the roughness parameters R.sub.z and R.sub.t used here.

TABLE-US-00002 List of reference signs 1 Material 1′ Paintable material 1″ Painted material 2 Surface made of a plastic containing amino groups 3 Structuring 4 Uppermost layer 5 Carrier board 6 Backer 7 Core 8 Functionalizing reagent 9 Vinyl group 10 Spacer 11 Covalent bond 12 Layer of radiation-curing paint 13 Primer or undercoat layer 14 First feed conveyor belt 15 Second feed conveyor belt 16 Third feed conveyor belt 17 Belt conveyor system 18 Melamine resin impregnated decorative paper 19 Melamine resin impregnated overlay paper 20 Press stack 21 Short-cycle press 22 Structured press sheet 23 Apparatus for applying the functionalizing reagent 24 First radiation source 25 High-energy radiation 26 Apparatus for applying of the radiation-curing paint 27 Excimer radiation source 28 Excimer radiation 29 Second radiation source 30 Feeding conveyor belt

DESCRIPTION OF THE INVENTION

[0118] FIG. 1 shows a plan view of a paintable or painted material 1 according to the invention. In both cases, the characteristic structuring 3 of the surface can be seen (structured surface of plastic containing amino groups or structured paint surface), which in the embodiment shown simulates a wood grain. The material 1 is board-shaped and may have a decor (e.g., a wood decor) that is consistent with the structuring 3. The material 1 has a surface made of a plastic containing amino groups 2, into which the structuring 3 is introduced.

[0119] FIG. 2 shows cross-sections through three exemplary materials 1 that can be used according to the invention and may look as shown in FIG. 1 in plan view. The material 1 shown in FIG. 2a is a laminate consisting of a carrier board 5, an underlying backer 6 and an overlying uppermost layer 4. The backer 6 is typically a paper soaked in synthetic resin, which is used to equalize the tensions on the top and bottom side. The carrier board 5 can be a wooden material board, such as an MDF or HDF board. However, it can also be a plastic or compact board made of kraft papers impregnated with phenolic resin. The uppermost layer 4 typically consists of at least one melamine resin impregnated decorative paper and an overlying melamine resin impregnated overlay, which have been hot pressed together with the carrier board 5 and the backer 6 to form the material 1. This causes the layers of the laminate to bond together and the melamine or synthetic resin to cure. On the upper side of the uppermost layer 4 of material 1, there is a surface of a plastic containing amino groups 2 because of the cured melamine resin present there. The amino groups are terminal remaining primary amino groups and the secondary amino groups of the cured melamine resin (melamine-formaldehyde resin).

[0120] Also visible in the cross-section is the structuring 3 of the surface already shown in plan view in FIG. 1, which is shown here schematically as indentations, as can be produced for example with structured press sheets. However, it is of course also possible to apply structuring measures (e.g., 3D printing), which would then result in elevations in the surface or a combination of elevations and depressions. The shown surface of plastic containing amino groups 2 may already have been functionalized with vinyl groups according to the invention, in which case the material 1 is a paintable material 1′ according to the invention. Otherwise, the material 1 shown is the starting material for the method according to the invention for producing the paintable material 1′.

[0121] The material 1 shown in FIG. 2b represents a layered material, e.g., a compact board. The core 7 is formed by a stack of phenolic resin impregnated kraft papers (e.g., 90 layers), and the uppermost layer 4 can again be a melamine resin impregnated decorative paper and an overlying melamine resin impregnated overlay, as in FIG. 2a, which together with the core 7 of impregnated papers have been hot pressed to form the material 1. What has already been said about FIG. 2a applies accordingly to the other characteristics.

[0122] As shown in FIG. 2c, the material 1 can also be just a carrier board 5 provided with structuring 3. Said carrier board has a surface made of a plastic containing amino groups 2. The carrier board 5 may, for example, be made of or coated with the plastic containing amino groups. The carrier board 5 may also be a wooden material board (e.g., particleboard, fiberboard or OSB board) obtained from particles containing lignocellulose which have been glued with an aminoplastic binder and pressed to form the wooden material board. The amino groups on surface 2 are then terminal remaining primary amino groups and the secondary amino groups of the cured aminoplast resin. The carrier board has structuring 3 at least on the top surface 2. What has been said for FIG. 2a applies accordingly.

[0123] FIG. 3 schematically shows a detailed view of the reactions that occur on the surface of a plastic containing amino groups 2 shown in FIGS. 1 and 2 during functionalization with the functionalizing reagent 8 according to the invention. In FIG. 3a and FIGS. 3c, a single secondary amino group (-NHR) is shown representatively in each case in the surface made of a plastic containing amino groups 2. It goes without saying that the surface made of a plastic containing amino groups 2 will contain many such secondary, but also primary amino groups (—NH.sub.2), each of which can also react appropriately with the functionalizing reagent 8. The functionalizing reagent 8 has at least three molecular moieties: (1) a first functional group A, which has a vinyl group 9, (2) a second functional group B, this being a group reactive toward the amino groups of the plastic containing amino groups, and (3) the intervening molecular moiety, referred to herein as the “spacer” 10. In case of more complex molecules, the spacer length denotes the shortest path between groups A and B. Preferably, the spacer length is between 2 and 20 carbon atoms, in particular between 2 and 10 carbon atoms, although other heteroatoms may be present between the carbon atoms. The functionalizing reagent 8 is thus an at least bifunctional molecule, since it has at least the functional groups A and B.

[0124] In FIGS. 3a and 3b, the functionalizing reagent 8 is shown only schematically. The functional group A shown in FIG. 3a may be any functional group comprising a vinyl group 9. Group A can also consist of a vinyl group. The functional group B shown in FIG. 3a may be any group reactive toward the amino groups of the plastic containing amino groups. Group B may be, for example, an epoxide, acid anhydride, acid chloride, acid azide, sulfonyl chloride, ketone, aldehyde, carboxylic acid, ester, especially N-hydroxysuccinimide ester, imido ester, or carbonates, carbodiimide, isocyanate, isothiocyanate, alkyl halide, aryl halide, alkyne, or a vinyl group, such as acrylate, methacrylate, or acrylamide. In FIGS. 3c and 3d, hexanediol diacrylate (HDDA) is shown as an example of a specific functionalizing reagent 8. In this symmetrically structured molecule, both group A and group B are acrylate groups. The spacer 10 here consists of six —CH.sub.2—groups.

[0125] According to the invention, the functionalizing reagent 8 is applied to the surface made of a plastic containing amino groups 2, resulting in the arrangement shown schematically in FIGS. 3a and 3c. By setting the appropriate reaction conditions, a reaction occurs at the surface 2 between amino groups present there and the reactive group B of the functionalizing reagent 8, and thus the functionalizing reagent is grafted onto an amino group at the surface of the plastic containing amino groups, forming a covalent bond 11 as shown in FIGS. 3b and 3d. The surface 2 has thus been covalently functionalized with vinyl groups 9, which are now available there for reaction with, for example, a radiation-curing paint. FIGS. 3b and 3d) thus show a detailed view of the functionalized surface of a paintable material 1′ according to the invention.

[0126] The reaction conditions, which are symbolically represented by a reaction arrow between FIGS. 3a and 3b or respectively 3c and 3d, depend strongly on the nature and chemistry of the reactive group B in the functionalizing reagent. If the reactive group B is a vinyl and in particular an acrylate group, irradiation with high-energy radiation such as electron beams or UV light is sufficient for the aza-Michael addition shown in FIGS. 3c and 3d to occur.

[0127] The material surfaces functionalized with vinyl groups can then be painted or stored. When a non-reversible reaction is chosen for functionalization (e.g., aza-Michael addition), material surfaces functionalized with vinyl groups have proven to be well storable. However, it is also advantageous to further process the functionalized material surfaces directly, in particular to paint them, since in this case, excess functionalizing reagent does not interfere and, on the contrary, can be directly incorporated by polymerization into the paint layer. In the case of storage, it is recommended to take precautions to avoid soiling or smearing, such as individual board storage, storage with intermediate layer or cleaning off the excess. According to a preferred embodiment, functionalization with vinyl groups is immediately followed by painting of the functionalized material surface.

[0128] If painted directly, it does not interfere because the reagent is incorporated by polymerization. FIGS. 4a – 4c show the materials already discussed in connection with FIGS. 2a – 2c, but this time after vinyl functionalization according to the invention and subsequent painting. Directly on top of the uppermost layer 4, which has been functionalized with vinyl groups (not shown), there is now a layer of radiation-curing paint 12. For example, a commercially available acrylate topcoat can be applied directly to a structured melamine resin surface functionalized according to the invention in a layer thickness of 5-15 g/m.sup.2. The fact that primers or undercoats can be dispensed with according to the invention means that the paint layer 12 can be applied in such a thin layer that the structuring 3 present in the uppermost layer 4 of material 1 is retained even after painting (compare FIGS. 2a – 2c before painting with FIGS. 4a – 4c after painting). It is thus possible, for example, to obtain structured aminoplast resin surfaces, such as those shown schematically in plan view in FIG. 1, in painted form. The inventors have surprisingly found that when such a surface structuring 3 is combined with a matte paint 12 or an excimer curing of the paint layer 12, natural-looking material surfaces that are virtually indistinguishable from the original (e.g., real wood parquet) in terms of appearance, feel and temperature sensation, while having improved surface properties (e.g., micro-scratch, weathering and chemical resistance) are created.

[0129] FIG. 5 serves to illustrate the advantages of the invention compared to the prior art. FIG. 5a shows an enlargement of the cross-section through the uppermost layer 4, such as can also be seen in FIGS. 2a – 2c. The uppermost layer 4 has a structuring 3 and is made of or contains a plastic containing amino groups (e.g., a melamine resin), providing it with a surface of plastic containing amino groups 2. If such a melamine resin surface were to be painted with a radiation-curing paint 12 according to the prior art (e.g., an acrylate paint), a primer or undercoat layer 13 would first have to be applied to the structured melamine resin surface, since radiation-curing paints adhere very poorly to it. The multi-layer paint structure 12, 13 results in a considerable paint layer thickness -compared to the largest elevation and depth difference in structuring 3 (Rz value). Overpainting causes the structuring to be lost. According to the prior art, it therefore makes no sense, for example, to paint over a melamine resin surface having a wood structure (cf. FIG. 1), as is frequently used, for example, as a furniture surface or flooring laminate. Such painting would nullify any structuring that was originally introduced.

[0130] By contrast, the invention makes it possible to paint over structured aminoplast resin surfaces. FIG. 5c shows a paintable surface according to the invention, similar to FIG. 5a as an enlargement of the cross-section through the uppermost layer 4, as also shown for example in FIGS. 2a – 2c. As in FIG. 5a, the uppermost layer 4 in FIG. 5c also has a surface of plastic containing amino groups 2, into which a structuring 3 has been introduced. However, as is apparent from a comparison of FIG. 5a with 5c, the paintable material 1′ according to the invention in FIG. 5c has a surface functionalized with vinyl groups 9 (see also FIGS. 3b and 3d). As shown in FIGS. 5d, a layer of radiation-curing paint 12 can be applied directly to this surface functionalized with vinyl groups 9 according to the invention, without first having to apply a primer or undercoat layer 13. FIG. 5d shows the applied layer of radiation-curing paint even before radiation curing, as can be seen from the vinyl groups 9 still being present. During the radiation-induced radical polymerization of the paint layer 12, the vinyl groups 9 present on the surface 2 polymerize into the paint film, which is thereby covalently anchored in the uppermost layer 4 of the material. This explains the observed excellent adhesion of radiation-curing paints to the paintable material surfaces provided by the invention. Since the vinyl groups 9 introduced into the surface 2 react into the paint during radiation-curing, they are no longer detectable following radiation-curing of the paint layer 12. In cross-section, therefore, a material painted according to the invention simply appears as if no primer or undercoat layer had been used. Only the paint film itself is visible on the substrate.

[0131] In contrast to the prior art (see FIG. 5c), according to the invention, when a structured material surface is painted, its structuring is retained even after painting, since substantially lower paint layer thicknesses can be achieved if the primer or undercoat layer is omitted. FIG. 5d therefore shows the structured paint layer present in the painted material according to the invention, which corresponds to the structuring of the material surface before painting (cf. FIGS. 5a or 5c with FIG. 5d).

[0132] FIG. 6 shows an example of a system and a method for producing a paintable material according to the invention, which is then directly further processed to a painted material according to the invention. Via a first, second and third feed conveyor belt 14, 15, 16, a wooden material board as carrier 5 with backer 6 on the underside (shown as liquid backer attached to the underside, the latter can also be fed via a separate fourth feed conveyor belt) as well as a melamine resin impregnated decorative paper 18 and melamine resin impregnated overlay 19 are placed on a feed conveyor belt 30 as press stack 20. For simplicity, the feed conveyor 30 is drawn as a continuous conveyor belt. In practice, however, this involves several separate conveyor belts whose speeds and surface properties are adapted to the respective method step. The press stack 20 then passes through a short-cycle press 21, which is equipped with a structured press sheet 22 on the side facing the overlay paper. In this example, the structure provided in the press sheet is the negative image of the wood grain shown in FIG. 1. In the short-cycle press, the press stack is pressed at 180° C. to 230° C. and a specific pressing pressure (active pressure on the board surface) of 50 to 300 N/cm.sup.2 to form material 1, which is a laminate panel having a surface 2 containing amino groups and provided with a structuring 3. Both terminal primary amino groups and secondary amino groups are present in the cured melamine resin at surface 2. Material 1 corresponds to a material having a structured surface known from the prior art, as it is produced in many variations as flooring or furniture components and is already available in intermediate stock.

[0133] The production of material 1 is therefore shown in the upper part of FIG. 6 for the sake of completeness only. Material 1 is storable and the method can be interrupted here. Above all, the numerous materials 1 already available with structured surfaces 2, 3 containing amino groups can be used in practice. These can be introduced to the method according to the invention for surface functionalization with subsequent painting without pretreatment. This is another advantage of the solution according to the invention.

[0134] The material 1 with structured surface 2, 3 containing amino groups is fed to an apparatus 23 for applying the functionalizing reagent 8 according to the invention. In the embodiment shown, a functionalizing reagent having two acrylate groups is used (e.g., dipropylene glycol diacrylate, tripropylene glycol diacrylate, or hexanediol diacrylate). In the apparatus 23, the functionalizing reagent 8 is applied to the structured surface 2, 3 containing amino groups of the material 1. In FIG. 6, the application of the functionalizing reagent 8 in the apparatus 23 is shown as spraying. However, numerous alternative application methods are also possible as detailed in the description, in particular application via a roller as shown in FIG. 6 for the apparatus for applying the radiation-curing paint 26.

[0135] In the next step, the applied functionalizing reagent 8 is caused to react with the amino groups on the surface 2 of the material by setting the appropriate reaction conditions. If the group in the functionalizing reagent that is reactive toward the amino groups of the material surface is a vinyl group, in particular one that is adjacent to an electron-withdrawing group (such as in an acrylate group), the reaction can take the form of a radiation-induced aza-Michael addition.

[0136] For this purpose, the surface 2 of material 1 containing amino groups and to which functionalizing reagent 8 has been added is exposed to a radiation source 24. The high-energy radiation 25 (e.g., UV or electron beams) impinges on the surface 2, where it leads to an aza-Michael addition of an acrylate group of the functionalizing reagent 8 to amino groups in the surface 2 (cf. FIGS. 3a - 3d). The functionalizing reagent 8 is thereby grafted onto the surface 2 of the material, resulting in covalent functionalization of the surface 2 with vinyl groups. The material 1′ functionalized in this manner constitutes the paintable material of the invention.

[0137] The paintable material 1′ can be painted with a radiation-curing paint 12 directly afterwards or in a separate method. For this purpose, the material 1′ passes through an apparatus 26 for applying the radiation-curing paint 12. FIG. 6 shows the application of the paint in apparatus 26 by a roller, however, all methods otherwise known to the person skilled in the art for applying radiation-curing paints are also possible. The applied layer 12 of radiation-curing paint is then cured by high-energy radiation 25, 28 in a manner known from the prior art. In the system shown in FIG. 6, an upstream excimer radiation source 27 is provided in addition to the second radiation source 29 actually required for curing (e.g., a UV lamp or an electron radiator). In this process, the applied paint layer is exposed to excimer radiation 28 (172 nm), resulting in the microstructuring of the paint surface described in more detail in the description. The resulting paintable material 1″ thus not only has a macroscopically structured paint surface corresponding to the surface structuring 3 present in the paintable material (e.g.,

[0138] wood grain, see plan view in FIG. 1), but also an additional microstructuring which produces a special matt finish and also gives the surface of material 1″ anti-fingerprint properties.

[0139] FIG. 7 shows a diagram illustrating the determination of the characteristic values Rz, Rz Max and Rt measured according to DIN EN ISO 4287. Where Rz means: averaged difference of highest and lowest profile (average of the five Rz values shown 1 to 5); Rz Max: highest measured point (largest Rz value determined); Rt: total height of the profile (distance between the highest peak and the lowest valley of the profile over the entire evaluated length In).

Exemplary Embodiments

[0140] Industrially manufactured laminate flooring or furniture surface panels having a structured melamine resin surface from the production of the EGGER company were used in all exemplary embodiments. These were CPL boards having the following layer structure: Backer, MDF core, melamine resin impregnated decorative and overlay paper, with the subsequent structures having been embossed into the latter during pressing by means of appropriately designed press sheets: [0141] ST67 F870 Slate decorative paper, trade name “CERAMIC”, with irregular rough character (all-over structure/no synchronous structure) [0142] ST69 “Natural Pore” decorative paper – Authentic, true-to-decor wood grain in combination with synchronously running surface structure [0143] ST28 “Gladstone Oak” decorative paper (look of classic planked oak), in combination with the synchronous surface structure ST28 Feelwood Nature (feel of sandblasted oak). [0144] F1 wood grain in all-over structure

Test Series 1

[0145] As indicated in the table below, the structured melamine resin surfaces of the boards were either not subjected to any treatment at all (comparative examples 1, 3, 5 and 8) or 0.5 g/m.sup.2 of hexanediol diacrylate (HDDA) was applied by roller application and then irradiated with a UV lamp (examples 2, 7 and 10 according to the invention; irradiation was performed with an 80 watt mercury lamp, at a 10 m/min feed rate with the dose of UV-A >350 mJ/cm.sup.2) or a commercially available UV primer for melamine resin surfaces (ICA UVF5782) was applied in an amount of 4 or 4–5 g/m.sup.2 by roller application and was partially gelled by UV irradiation (comparative examples 4, 6 and 9; irradiation was also performed with an 80 watt mercury lamp, at 10 m/min feed rate with the dose of UV-A >350 mJ/cm.sup.2). The surfaces, which were vinyl-functionalized with HDDA according to the invention or primed according to the prior art, were then painted with commercially available UV topcoat compositions (acrylate coating, ICA UVS5595) and UV cured according to the manufacturer’s instructions. For this purpose, after the topcoat application at 15 m/min, excimer curing (company IST) was performed first, followed by double irradiation with 120 W mercury lamps for final curing.

[0146] The gloss value under 60° and 85° was determined according to ÖNORM EN ISO 2813 (version 2015-01-01). The surface condition was also determined using the profile method according to DIN EN ISO 4287 (October 1998 version). The definition of the Rz value is as given in the description and in FIG. 7.

[0147] The adhesion was determined by means of “Hamberger Hobel”, a standardized testing device from Hamberger Industriewerke, with which a coin test can be performed under defined conditions. A metal piece with a coin-like edge is pushed over the painted area with an adjustable pressure. The result is the force in newtons at which no stress whitening is yet detectable. All results above 15 newtons can generally be considered acceptable.

[0148] The following test results were obtained:

TABLE-US-00003 Sample Functionalization with vinyl groups UV primer UV topcoat Gloss 60° Gloss 85° Rz Δ Rz Hamberger Hobel 1* ST67 - - - 6.2 12.8 21.3 >40 N 2 ST67 0.5 g/m.sup.2 HDDA, UV - 7 g/m.sup.2 3.2 6.9 24.9 3.6 >40 N 3* ST 69 - - 5.2 10.6 61.1 >40 N 4** ST 69 - 4 g/m.sup.2 12 g/m.sup.2 1.8 14.2 22.1 39.0 < 15 N 5* ST 28 - - - 4.1 10.8 55.1 - > 30 N 6** ST 28 - 4-5 g/m.sup.2 7-8 g/m.sup.2 5.8 32.1 43.7 -11.4 < 10 N 7 ST 28 0.5 g/m.sup.2 HDDA, UV - 7 g/m.sup.2 3 11.2 70.9 15.8 >30 N 8* F1 - - - 8.4 23.2 35.1 >40 N 9** F1 - 4-5 g/m.sup.2 7-8 g/m.sup.2 7.6 28.4 28.4 -6.7 < 15 N 10 F1 0.5 g/m.sup.2 HDDA, UV - 7 g/m.sup.2 3.1 12.3 38.0 2.9 >40 N * Not according to the invention (starting product, structured melamine resin surface) ** Not according to the invention (over painted with UV primer and UV paint)

[0149] A comparison of samples 1* and 2 shows that with the functionalization according to the invention it is possible to apply a UV paint directly to a melamine resin surface without any deterioration of the adhesive bond (Hamberger Hobel Coin Test). By using a matte UV paint, the unnaturally high-gloss melamine resin surface can be given a matte appearance (gloss 60° at approx. 3, cf. examples 2, 7 and 10 according to the invention with the corresponding melamine resin surfaces 1*, 5* and 8*) and yet its structured surface matching the decor can be retained or even enhanced (difference [Δ] in the Rz values unchanged to positive in examples 2, 7 and 10 according to the invention). In contrast, the application of a layer of standard UV primer followed by painting results in a strong decrease of the Rz value after painting (see negative difference [Δ] of the Rz values in the comparative examples 4**, 6** and 9**) even with the relatively thin layer thicknesses used (usual for UV primers up to 10 g/m.sup.2, and for topcoats up to 15 g/m.sup.2).

[0150] In addition, the micro-scratch resistance of the surfaces was determined according to DIN EN 16094 (Martin Dale standard for flooring). (Rating 1-5; 1 best rating, 5 worst rating)

TABLE-US-00004 Surface – not painted, (samples 1*, 3*, 5* and 9*) Surface – painted (samples 2, 7 and 10) Martin Dale Test A >A2 A1 Martin Dale Test B >B3 B1

[0151] While the unpainted melamine resin surfaces were very susceptible to micro-scratches, the micro-scratch resistance could be significantly increased by the painting according to the invention, while retaining the original structuring.

[0152] The evaluation of samples 1 to 10 was also performed in a blind test by trained experts of the company EGGER. This evaluation showed that samples 2, 7 and 10 according to the invention had by far the most natural appearance of all 10 samples and could hardly be distinguished from the original to be imitated (veneer/real wood surface, stone/ceramic decors or respectively textile decorative pattern with smooth structure) in terms of their appearance as well as their feel and touch temperature.

Test Series 2

[0153] Similar results to those obtained with the UV primer ICA UVF5782 and topcoat ICA UVS5595 used in test series 1 were also obtained in numerous tests with other commercially available UV primers (tested: Plantag 74170, Remmers UV120-112, Teknos E114203, Sherwin Williams UL/61099-469, Votteler L5405524) and topcoats (tested: Plantag 75773.6, Teknos E120239, Bergolin 2U073, Bona 7720, Akzo Nobel UV TOP 103939). The vinyl functionalization according to the invention was always superior to the commercially available UV primers due to the lower layer thickness and better adhesion.

Test Series 3

[0154] A test series was performed as described for test series 1, except that BDDA was used as the functionalizing reagent instead of HDDA. The results were similar to those of test series 1. The vinyl functionalization according to the invention was always superior to the commercially available UV primers due to the lower layer thickness and better adhesion.

Test Series 4

[0155] A test series was performed as described for test series 1, except that DPGDA was used as the functionalizing reagent instead of HDDA. The results were similar to those of test series 1. The vinyl functionalization according to the invention was always superior to the commercially available UV primers due to the lower layer thickness and better adhesion.

Test Series 5

[0156] A test series was performed as described for test series 1, except that TMPTA was used as the functionalizing reagent instead of HDDA. The results were similar to those of test series 1. The vinyl functionalization according to the invention was always superior to the commercially available UV primers due to the lower layer thickness and better adhesion.

Test Series 6

Example 1:

[0157] In an analogous manner as described for test series 1, a furniture surface decor H3399 having the structure ST28 (raw template) was functionalized with HDDA (1 g/m.sup.2).

[0158] For the comparative example, a commercially available UV primer (Plantag Primer 74170.5) was used instead at an application amount of 4 g/m.sup.2. According to the technical data sheet, it contains: Propylidynetrimethanol, ethoxylated, ester with acrylic acid; 2-ethylhexyl acrylate and 2-hydroxy-3-phenoxypropyl acrylate. In both cases, a UV paint by the company Plantag 78700.1 (8 g/m.sup.2) was applied as topcoat. According to the technical data sheet, it contains: 1,6-hexanediol diacrylate, acrylic resin and methylbenzoyl formate. In contrast to test series 1, however, no excimer curing was performed. The following results were obtained:

TABLE-US-00005 Rt value Gloss level Hamberger Hobel Martin Dale (DIN EN 16094) Raw template 78.8 .Math.m 4.1 (60°) 40 N B2 / A3 HDDA + Plantag Topcoat 78700.1 78 .Math.m 7.3 (60°) 40 N B1 / A1 Plantag Primer 74170.5 + Plantag Topcoat 78700.1 73 .Math.m 8.5 (60°) 10 N B1 / A1

Example 2:

[0159] In an analogous manner as described for test series 1, a flooring panel having wood decor H1007 “Parquet Oak” and a flatter structure as surface was functionalized with DPGDA (application amount 1.5 g/m.sup.2). For the comparative example, a commercially available UV primer (UVILUX Primer 621-183) was used instead at an application amount of 4 g/m.sup.2. According to the technical data sheet, it contains: exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acrylate, dipropylene glycol diacrylate, 2-propenoic acid, 2-methyl, 2-hydroxyethyl ester and ethyl phenyl (2,4,6-trimethylbenzoyl)phosphinate. In both cases, a UV topcoat of the company Bona (article no. 7720, acrylate paint, application amount 8 g/m.sup.2) was applied and cured with excimer as described in test series 1. The following results were obtained:

TABLE-US-00006 Rt value Gloss level Hamberger Hobel Martin Dale (DIN EN 16094) Raw template 49 .Math.m 8.4 (60°) 40 N B2 / A3 DPGDA + Bona UT 7720 47.2 .Math.m 3.1 (60°) 40 N B1 / A1 UVILUX Primer 621-183 + Bona UT 7720 36 .Math.m 3.3 (60°) 12 N B1 / A1

Example 3:

[0160] In an analogous manner as described for test series 1, a panel with synchronous structure ST 69 on the wood decor H2820 as surface was functionalized with 0.5 g/m.sup.2 TMPTA. For the comparative example, a commercially available UV primer (Bergolin 1U080) was used instead at an application amount of 4 g/m.sup.2. According to the technical data sheet, it contains: 4-(1,1-dimethyl)cyclohexyl acrylate, (5-ethyl-1,3-dioxan-5-yl)methyl acrylate, ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate and 1,1,1-trihydroxymethylpropyl triacrylate. Bergolin UV Topcoat 2U080-090, colorless (unsaturated acrylate resin, 11 g/m.sup.2) was used as topcoat in both cases and cured with excimer as described in test series 1. According to the technical data sheet, the topcoat contains: 1,6-hexanediol diacrylate (5-ethyl-1,3-dioxan-5-yl)methyl acrylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacat ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate and 1,1,1-trihydroxymethylpropyl triacrylate. The following results were obtained:

TABLE-US-00007 Rt value Gloss level Hamberger Hobel Martin Dale (DIN EN 16094) Raw template 65 .Math.m 10.4 (60°) 35 N B2 / A3 TMPTA + Bergolin 2U080 63.8 .Math.m 1.8 (60°) 35 N B1 / A1 Bergolin 1U080 + Bergolin 2U080 54.2 .Math.m 5.2 (60°) 10 N B2 / A2

[0161] As a comparison of the Rt values to examples 1 to 3 shows, the structure is always best preserved with the painting according to the invention. Surfaces painted according to the invention have similarly good Hamberger Hobel results as the melamine resin starting surfaces (raw template), but achieve similarly good values in the Martin Dale test as melamine resin surfaces overpainted with UV paint.