HK1082712B - Sheet-or web-like, decorative coating film and method for producing the same - Google Patents

Description

The present invention relates to a process for the manufacture of a decorative sheet or rail coating material, in particular a coating film, such a decorative coating film and its use.

Decorative coating films, such as finishing films, are generally known from the state of the art, for example, they are used in the manufacture of furniture and, exceptionally, in the manufacture of laminate flooring.

In particular, in this area of application or for the coating of other areas with high stress, such as in the kitchen or industrial production sector, the abrasion resistance of a coating produced with a coating film is particularly important. The state of the art has shown that methods are available for the use of corundum-containing, duroplastic resins for laminate flooring; the corundum is either contained in a (mostly filler-free) paper carrier, which is then soaked with melamine formaldehyde resin, or suitable papers are imprinted with suitable corundum-containing resins (see, for example, DE 081957 C 791).

An alternative method for the production of abrasion-resistant coatings is revealed in DE 42 19 446: fillers (usually corundum) are added to radiation hardening binders, and the binders are then applied to a carrier in liquid form.

However, the two methods described above are only partially suitable, as far as the state of the art is concerned, and under certain conditions, for the production of film-like coatings which can be cashed and coated at will (i.e. which are highly flexible), since coatings with duroplastic and beam-meshed binders are very brittle, especially with higher layer thicknesses and high mesh density.

DE 41 18 731 A1 describes a method for the production of a coating film in which a supporting layer is successively covered with two layers of wet-in-wet resin, the resin material is matted and a joint curing by electron beam is performed to produce a scratch-resistant film.

The method and device for producing matte coating surfaces are known from EP 0 296 395 A2, which in turn involves the application of two successive coatings of coating on a film substrate, but each layer is irradiated according to the order.

The present invention is therefore intended to create a decorative coating material, in particular in the form of a decorative coating film, which is significantly more flexible than the materials known from the state of the art and is therefore suitable for surface covering and coating tasks, and which is also in a flat shape and does not roll up unwantedly after the manufacturing process has ended.

The problem is solved by the process with the features of the main claim, the coating film with the features of the independent claim 13 and the use after the patent claim 17.

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Such a binding system as a base layer in the present invention is advantageous, on the one hand, in ensuring that the fillers (e.g. corundum) which produce the abrasion resistance can be kept with a high binding effect, but at the same time such a coating is suitable in addition to the extremely adhesive application of the cover layer (covering), whereby, according to the invention, the radial network extending through two layers (covering layer and base layer) ensures good adhesion. Furthermore, the cover layer allows the flat surface to be completely covered by corundum. Accordingly, such a coating can be used to prevent any damage (split or corrosion) resulting from the production process, which can then be effectively prevented by the manufacturing process.

Finally, the binder according to the invention is characterized by high transparency, so that a pattern (e.g. a print) formed in a continuous manner on the underlying paper or plastic support layer remains visible in high image quality after the layering is completed.

The measures described above will then achieve a surprisingly high abrasion resistance of the coating film produced; using the abrasion resistance measurement criteria regulated in EN 13329 values well above 2500 revolutions will be achieved, so that the abrasion class AC3 coatings can be produced in the manner described, which is well above what is possible with the state of the art described at comparable layer thicknesses.

While it is preferable to apply the coating without solvent (so that after curing or interlacing the layer thickness, which is preferably in the range of about 10 to 30 micrometres, remains unchanged in the wet state), it is also possible to use radiation hardened resins for the coating in an aqueous dispersion.

While the invention provides for the coating to be made without abrasive fillers (Al2O3, SiO2, etc.) and, furthermore, without thermal hardening resins, the present invention does not preclude the addition of pigments (such as TiO2) to the coating for staining purposes or the modification of the coating resin by so-called nanoparticles to improve scratch resistance; for the additional disclosure, reference is made to WO 00/22039, which is intended to be included in the present disclosure for the modification process by nanoparticles.

It is particularly desirable to structure the cover layer according to the following methodology before the interlocking: if the underlying support layer has a printing or similar pattern, it is desirable to make a structure of the cover layer corresponding to this (wood) printing or grain effect by aligning the structuring tools according to the pattern.

The present invention provides an advantageous way of producing a coating film which is suitable for use as cashew film: not only does it (compared with the products known from the state of the art) have significantly increased flexibility (so that even problematic cashew film tasks, such as the coating of profile bars or furniture parts, can be carried out without problems and without fractures or cracks), but the process product according to the invention is also exceptional and does not tend to be partially rolled up or unrolled.

It should be noted that, unlike some products known from the state of the art, the process product of the invention is structurally finished, in particular, in a subsequent coating or casing process on a casing carrier, no further structural or chemical modification of the coating takes place.

According to the further training in the framework of the invention, the desired gloss can be adjusted by adding matting agents; gloss between five and eighty (measured according to DIN 67530 at 60°) is realistically achievable.

Not least because of their superior abrasion resistance values, well above 2500 U (measured according to the method S42 according to EN 13329) the product of the invention or the decorative coating film according to the invention is suitable for high-strength coating surfaces such as floor tiles or floor panels.

Furthermore, since, in comparison with abrasion-resistant surfaces known to the present state of the art, either the abrasion properties are significantly improved or products with comparable abrasion strengths would have a significantly greater layer thickness (with the associated disadvantages of brittleness and lack of suitability for coatings requiring flexibility), it is to be expected that the present invention of the abrasion-resistant coating will open up completely new fields of application and application.

The following illustration of the design, which is the only one to be found in the presentation, shows the advantages, features and details of the invention. Fig. 1 the schematic layer structure of the decorative coating film according to a first preferred embodiment of the present invention.

The rail-shaped support shown in Fig. 1 typically has a 35 to 90 micrometer thick layer of printed paper as the support layer 10. The printing is done in the direction of a two-layer coating, namely a base layer 12 applied directly to the paper layer 10 and a cover layer 14 applied to it. While the base layer 12 is formulated to achieve maximum abrasion resistance and contains abrasive inorganic fillers (in particular Al2O3 and SiO2), the cover layer serves, among other things, to seal the base layer and determines the other surface structural properties, in particular the degree of gloss, surface aesthetics and flatness.

The base layer, with otherwise known coating aggregates as rolling order, applied by means of a slit nozzle or coma rake with a typical layer thickness between about 10 and 100 micrometres, contains aqueous radiation hardening resins between 22% and 95% (in the example: 40%) and inorganic fillers in the form of abrasives as described above, as well as additional colouring pigments (e.g. TiO2) in the range of 10% to 70% in the example, approximately 60%.

A typical formula for the production of the base layer 12 coating material could be implemented as follows:60 parts aqueous radiation hardening resin (IRR 395, 40%ig)40 parts filler (Plakor 30).

The coating is made of a radiation hardening binder which may be either completely solvent free or a radiation hardening aqueous dispersion (max. approximately 50% to 90% water).

Furthermore, the degree of gloss can be adjusted as desired by adding a matte finish (typical gloss between 5 and 80, DIN 69530 at 60°), and so-called slip additives can be added to further increase the scratch resistance.

A typical radiation hardened resin product for the realization of the coating layer is e.g. Ebecryl 1016. The order is again made by known coating possibilities, such as roller, slot nozzle or rackle order, whereby the application is done both inline (directly after a drying of the base layer), as well as in a separate step, offline and in a separate coating system.

The resulting coating film is characterised by very high abrasion resistance, above 1500 turns, usually above 2500 U (method S42 according to EN 13329).

This product is a so-called finishing film, since the binders of the top layer and the base layer are completely hardened and interlocked. Further processing, e.g. by coating on a suitable support material, does not alter the polymer properties. In particular, high pressure and high temperature processing is not necessary for coating.

The film product, in addition to the high abrasion resistance described above, is characterised by high flexibility and low brittleness, so that it can be used in particular in casing and cladding systems for the finishing of various products, such as wood panels, slats and mechanically heavy furniture parts.

Claims (19)

1. Process for producing a sheet-like or web-like decorative, abrasion-resistant coating material, in particular coating film, having the steps:

   - coating a support layer (10) made from paper and/or plastic with a liquid or pasty base layer (12) which is free of organic solvents, and which has aqueous, radiation-curing, but no thermally curing resins and an abrasive, preferably inorganic filler,

   - drying the support layer (10) coated with the base layer (12), in particular with heat supply,

   - applying a cover layer (14) containing a radiation-curing resin and no abrasive fillers to the dried, non-crosslinked base layer (12) and

   - joint curing or crosslinking of the cover layer and the radiation-curing resins in the base layer by irradiation of the cover layer using UV and/or electron rays.
2. Process according to claim 1, characterised in that the liquid or pasty base layer (12) is applied at a layer thickness between 10 and 100 micrometres or is applied at such a layer thickness that the base layer in the dried state has a thickness between 20 and 70 micrometres.
3. Process according to claim 1 or 2, characterised in that the cover layer (14) is applied at a layer thickness between 10 and 30 micrometres.
4. Process according to one of claims 1 to 3, characterised in that the radiation-curing resins of the base layer are an aqueous mixture of large-molecular and small-molecular prepolymers, wherein the particle size of the abrasive fillers is preferably adapted to a layer thickness of the base layer (12).
5. Process according to one of claims 1 to 4, characterised in that solvent-free or anhydrous resins or resins in a radiation-curing, aqueous dispersion, which has/have a water content of 70% maximum, are used as a cover layer.
6. Process according to one of claims 1 to 5, characterised in that the cover layer is structured before curing or crosslinking and also preferably the structuring of the cover layer takes place graphically synchronously with a pattern printed onto the support layer (10) before coating.
7. Process according to one of claims 1 to 6, characterised in that the radiation-curing resin of the cover layer is modified as regards its molecular structure by nanoparticles.
8. Process according to one of claims 1 to 7, characterised in that the support layer is a dry web which is selected from the group consisting of preimpregnated paper with thermal or radiation-crosslinkable binder, plastic film, wood veneer, fibrous web or flexible panel substrate.
9. Process according to one of claims 1 to 8, characterised in that drying of the base layer is effected so that the base layer coated with the support layer has a residual moisture below 1% or the support layer coated with the base layer is present being tack-free and windable.
10. Process according to one of claims 1 to 9, characterised by the application of a thermally reactive adhesive to the side of the support layer opposite to the base layer, wherein the adhesive has a coat weight in the range between 2 and 20 gr./m2, preferably 2 to 10 gr./m2, also preferably 2 to 5 gr./m2.
11. Process according to claim 10, characterised in that the adhesive has a reaction temperature < 160°C, preferably < 100°C.
12. Process according to claim 10 or 11, characterised in that the adhesive is selected and arranged so that the step of joint curing or crosslinking of the cover layer and of the base layer does not effect activation of the adhesive.
13. Process according to one of claims 1 to 12, characterised in that the steps of coating the support layer, drying the coated support layer, applying the cover layer and joint curing or crosslinking takes place in a constant, continuous process sequence (in-line).
14. Process according to one of claims 1 to 13, characterised by pressing of the decorative, abrasion-resistant coating material onto a support made from paper, plastic, wood or derived timber products by means of a static press or by means of a continuously operating double-band press at a pressure in the range between 1 and 80 bar and a temperature in the range between 100°C and 180°C.
15. Sheet-like or web-like decorative coating film having

    - a support layer (10) made from paper and/or plastic,

    - a base layer (12) formed on the support layer by aqueous application, and having a radiation-curing, but no thermally curing resin and an abrasive, preferably inorganic filler and

    - a cover layer (14) formed on the base layer and which has a radiation-curing resin jointly crosslinked with the resin of the base layer and no abrasive fillers,

    - wherein the layers are formed and the filler selected so that the coating film has an abrasion resistance of more than 1,500 revolutions, preferably of more than 2,500 revolutions, measured according to EN 13 329 (Method S42).
16. Coating film according to claim 15, characterised in that the base layer and the cover layer in the cured or crosslinked state have a common thickness of less than 50 micrometres and are transparent.
17. Coating film according to claim 15 or 16, characterised in that the support layer made from paper and/or plastic, which is visible through the base layer and the cover layer, has a sample.
18. Coating film according to one of claims 15 to 17, characterised in that the cover layer (14) has a structuring, wherein the structuring is synchronised graphically with a sample or print provided on the support layer.
19. Use of the coating film according to one of claims 15 to 18 for producing floors, in particular flexible floor elements, work panels, doors, window sills, furniture, surfaces of kitchens or of industrial or laboratory environments.