WO2020234268A1

WO2020234268A1 - Method for coating a surface

Info

Publication number: WO2020234268A1
Application number: PCT/EP2020/063905
Authority: WO
Inventors: Ingo Hörsting; Sebastian Frerick; Kai Thiele; Beatrice Wontora; Georg Bender
Original assignee: Brillux Gmbh & Co. Kg
Priority date: 2019-05-20
Filing date: 2020-05-19
Publication date: 2020-11-26
Also published as: EP3973023A1; DE102019113331A1

Abstract

The invention relates to a method for coating a surface, at least comprising the steps (1) applying a UV-curing glaze to a surface, wherein the UV-curing glaze contains, in relation to the total weight of the glaze in each case, 20 to 90 wt% of binder, 5 to 60 wt% of reactive diluent and 0.1 to 20 wt% of photo initiator, and wherein the UV-curing glaze has a viscosity of 10 to 1000 mPa-s at a shear rate of 1000 s^-1, (2) curing the glaze applied in step a. by means of UV-A radiation, and a system comprising a UV-curing glaze and a UV radiator, a use of a UV-curing glaze or of a system comprising a UV-curing glaze and a UV-radiator for coating a surface and a UV-curing glaze.

Description

Process for coating a surface

The invention relates to a method for coating a surface, a system comprising a glaze and a UV radiator, a use of a glaze or a system for coating a surface, and a UV-curing glaze.

Applying glazes to pieces of furniture, doors, door frames or garden furniture beautifies the glazed objects and protects the objects from external influences such as moisture, microbial infestation, oxidation processes and / or mechanical effects. In order to obtain the best possible adhesive, permanent and visually appealing glaze on an object, multiple applications of thin glaze layers are necessary. First of all, the surface of the object to be glazed is usually pre-processed before the first application, in particular by grinding. In the next step, the glaze is applied thinly to the surface using a brush or roller. You then have to wait until the glaze has completely hardened in order to sand the surface and reapply a thin layer of glaze. If necessary, these steps have to be repeated several times in order to be able to guarantee adequate protection of the object with good adhesion of the glaze. The complete hardening of the glaze is the most time-consuming step of the

Procedure. The complete hardening of common solvent-based glazes can take between six and twelve hours at room temperature, so that often several days have to be planned for coating objects. This is particularly problematic when immobile objects such as door frames are to be glazed by craftsmen on site at the customer's premises. This represents an organizational challenge for customers and craftsmen, which also entails considerable costs for the customer. One approach to solving this problem in the industrial sector is the use of solvent-free glazes, which can harden more quickly. These include 2-component systems, radiation-curing coatings and powder glazes.

Well-known solvent-free glazes are designed for industrial use in special coating systems and are not suitable for

Painter application on furniture, especially not for mobile use on the construction site.

In addition, with radiation-curing coatings such as UV-curing glazes, for example, there is the problem that the oxygen present in the atmosphere can hinder the complete and uniform curing of the glaze. Consequently, additional precautions must be taken regularly for the curing of UV-curing glazes, with which the oxygen content in the

Ambient air is controlled. This is achieved, for example, in UV coating systems through controlled, shielded chambers for the

UV curing of the coating. However, such an approach does not allow the flexible application of a coating glaze to objects such as furniture, doors or door frames directly at the customer's site.

The object of the present invention is thus to provide a method with which objects such as pieces of furniture, doors, door frames or garden furniture can be coated uniformly and completely in a short time. This should also be possible directly with the customer.

In addition, the glaze applied to the surface of an object in the course of the process should adhere well to the object, be resistant to mechanical effects and / or weathering and / or be visually appealing

Give up appearance. A further object of the invention is to provide a method that can be carried out simply and by means of which objects can be glazed with little effort.

Another object of the invention is to provide a method in which a glaze can be applied in a common application by means of rolling, brushing and spraying.

All or some of these objects are achieved according to the invention by a method according to claim 1, a system according to claim 25, a use according to

Claim 26, as well as a glaze according to Claim 28, solved.

Advantageous refinements of the invention are specified in the dependent claims and are explained in detail below.

Surprisingly, it has been found that the coating of furniture, doors, door frames and other objects can be accelerated considerably if a method is used for coating a surface which comprises at least the following steps:

a. Application of a UV-curing glaze to a surface, the UV-curing glaze, based on the total weight of the glaze,

i. 20 to 90% by weight binder,

ii. 5 to 60% by weight reactive diluent and

iii. 0.1 to 20 wt.% Photoinitiator,

contains and wherein the UV-curing glaze has a viscosity of 10 to 1000 mPa s at a shear rate of 1000 s ^-1 , and

b. Hardening the in step a. applied glaze using UV-A radiation.

With the method according to the invention, objects can be coated with common painting utensils directly on site. With the method according to the invention, a particularly uniform hardening of the applied glaze is achieved can also be applied particularly thinly and evenly in the course of the method according to the invention. The inventive method can

Surface coating can be sanded off directly after curing using UV-A radiation. In this way, a particularly efficient, quick and simple workflow can be guaranteed.

The UV-curing glaze used in the process according to the invention with a viscosity of 10 to 1000 mPa-s at a shear rate of 1000 s ^-1 can be applied with conventional painting utensils such as brushes or rollers and cured immediately afterwards using UV-A radiation. The mentioned viscosity enables the application of a glaze layer with a small layer thickness, whereby an excellent appearance is achieved. By setting the viscosity mentioned, the UV-curing glaze is optimally handleable for mobile use

Application and subsequent curing by means of UV-A radiation on site at the construction site. On the one hand, the selected viscosity ensures good penetration of the UV-curing glaze into the surface of the material to be coated, in particular wood. This contributes to the good adhesion properties of the coatings produced with the method according to the invention. On the other hand, the setting of the viscosity mentioned leads to a uniform viscosity

Coating result without undesired drop formation or smearing of the glaze. The method according to the invention also provides a film coating which protects the coated surface particularly well against mechanical and / or chemical effects.

In the context of the invention, glazes are understood to mean, in particular, coatings that have a maximum hiding power of 90% at 50 ml / m ² , measured in accordance with standard EN ISO 6504-3, in particular standard EN ISO 6504-3: 2007, method B on black and white cards (Section 5.1.2). Glazes within the meaning of the invention are in particular transparent or semitransparent or

translucent. Experimental studies have shown that, in particular, the ratio of binder, thinner reactive and photoinitiator to one another is of essential importance for the uniform curing of the UV-curing glaze. In this way, the glaze can be uniformly and completely cured on site directly at the customer's premises without any measures to control the oxygen concentration. With the method according to the invention, a considerable reduction in costs can also be achieved for the customer.

According to a preferred embodiment of the method according to the invention, the UV-curing glaze has a viscosity of 50 to 800 mPas, preferably from 100 to 700 mPas, more preferably from 200 to 600 mPas or, at a shear rate of 1000 s ^-1 particularly preferably from 300 to 500 mPa · s. It has been shown that a glaze with such a viscosity can be applied particularly well to surfaces with ordinary painting utensils such as brushes and rollers, adheres well to the surface, does not smear, has a long processing time and only when treated with UV-A - Radiation cures quickly and completely.

The desired viscosity of the UV-curing glaze can be achieved in different ways that are familiar to the person skilled in the art. One way to

Adjusting the viscosity consists in that a binder is selected as the binder of the UV-curing glaze which, at a shear rate of 100 s ^{-1, has} a viscosity of 65 to 300 mPa-s, preferably from 70 to 200 mPa-s or particularly preferably from 80 to 150 mPa-s. If the binder has a viscosity in this range, a homogeneous glaze can be produced particularly well, which can be easily applied to surfaces using common painting utensils.

Suitable binders are known to the person skilled in the art and are described in more detail below.

Alternatively or in combination, the viscosity can be adjusted by selecting a compound as the reactive diluent for the UV-curing glaze which, at a shear rate of 100 s ^{-1, has} a viscosity of 0.1 to 60 mPa · s, preferably of 1 to 40 mPa · s, preferably from 3 to 30 mPa · s or particularly preferably from 5 to 20 mPa · s. A reactive thinner with such a viscosity helps ensure that the glaze is sufficiently thin to be spreadable. In addition, a reactive thinner with such a viscosity can mix particularly well with the binder and in this way ensure a homogeneous glaze.

Suitable reactive thinner are known to the person skilled in the art and are described below by way of example.

When reactive thinners are mentioned here or elsewhere, substances are meant which reduce the viscosity of a glaze for processing and which are part of the subsequent hardening of the glaze by copolymerization

hardened glaze. The differences between binders and

Reactive diluents are known to the person skilled in the art. In particular, the reactive thinner has a lower viscosity than the binder.

Methods for determining the viscosity of coating agents are the

Known to those skilled in the art. In particular, the viscosity can be determined with an MCR 92 rheometer at a temperature of 20 ° C. In particular, a plate geometry (diameter 50 mm) can be used for plate-on-plate measurement (distance 0.5 mm). 100 s ^-1, or from 0.01 - - preferably a shear ramp of 0.01 s in this case is driven 1000 ^{sec -1.}

The choice of the amount and type of binder can have an impact on that

Curing speed of the UV-curing glaze after application on the

Have surface. According to a preferred embodiment, contains

UV-curing glaze from 30 to 80% by weight, preferably from 35 to 75% by weight, more preferably from 40 to 72% by weight or particularly preferably from 45 to 70% by weight, based in each case on the total weight of the glaze, binder . With this content of binder, a particularly complete and uniform curing of the UV-curing glaze can be achieved by means of UV-A radiation. Basically, any binders that can be cured by means of UV-A radiation are suitable for the UV-curing glaze. According to a preferred embodiment of the method according to the invention, the binder of the UV-curing glaze contains a compound selected from the group consisting of unsaturated esters, unsaturated polyesters, unsaturated ethers, unsaturated polyethers, epoxy acrylates, epoxy resins, (meth) acrylic acid, (meth) acrylic acid esters, polyester acrylates ,

Polyether acrylates, polyurethanes, polyurethane acrylates, glycidyl (meth) acrylates, unsaturated acrylate resins, polydialkylsilanes with terminal silanol groups, hydroxyalkyl acrylates, polydialkylsilanes with terminal epoxy groups,

alkoxylated trimethylol propane triacrylate and mixtures thereof. These

Compounds have proven to be particularly suitable for curing by means of UV-A radiation. In addition, these binders do not result in undesirable yellowing of the glaze. A combination of two different compounds as binders for the UV-curing glaze has proven to be particularly advantageous, since in this way particularly stable polymer networks can be formed.

A particular challenge when applying and curing a UV-curing glaze on objects such as furniture, doors, door frames or garden furniture at the customer arises from the oxygen, which can inhibit the curing of the glaze. Oxygen radicals can react with the polymerizing components of the binder and / or the reactive thinner of the glaze and lead to the termination or slowdown of the polymerization reaction. As a result, the glaze may not harden completely or evenly. Surprisingly, it has been shown that this problem can be completely overcome if the binding agent of the UV-curing glaze has at least one functional group, one of which is in a reaction with a radical

Hydrogen atom is split off homolytically.

If here or elsewhere from a functional group from which a hydrogen atom is homolytically split off in a reaction with a radical, the When we are talking about a group is meant that provides a hydrogen radical in reaction with a radical such as a peroxy radical. With homolytically split off it is meant that a hydrogen radical (and not a positively charged hydrogen ion) is released from the functional group.

The functional group by which to react with a radical one

Hydrogen atom is split off homolytically, can here for example be contained in one of the compounds mentioned above as binders, for example by modifying the corresponding compound by introducing such a functional group. Alternatively, a compound that has such a functional group can also be added to the glaze as a further compound. In this alternative, there are consequently at least two compounds next to one another as binders, the first compound preferably being a common binder that cures under UV-A radiation and the second compound being a compound which comprises a functional group , of which a hydrogen atom homolytically in a reaction with a radical

is split off.

According to a particularly preferred embodiment of the process according to the invention, the functional group from which a hydrogen atom is homolytically split off in a reaction with a radical is selected from thiol, amine and ether. With thiols, amines and / or ethers as the functional group, particularly uniform and rapid curing of the glaze can be guaranteed by means of UV-A radiation. Thiols have the highest reactivity and efficiency and are therefore particularly suitable for glazes that are to be used directly. However, with long storage times (over 6 months) under certain conditions (over 35 ° C), thiols can lead to an increase in the viscosity of the stored glaze due to side reactions. A particularly good one

On the other hand, storage stability can be achieved with amines and / or ethers as functional group, of which a hydrogen atom in a reaction with a radical

is split off homolytically, achieve. In a preferred embodiment of the method according to the invention, the binder contains a compound which contains both a functionality that leads to a polymerization reaction by means of UV-A radiation and a functional group from which a hydrogen atom is homolytically split off in a reaction with a radical . Such compounds include, for example, compounds selected from the group consisting of mercapto-, amino- or alkoxy-modified unsaturated esters, mercapto-, amino- or alkoxy-modified unsaturated polyesters, mercapto-, amino- or alkoxy-modified unsaturated ethers, mercapto- , amino- or alkoxy-modified unsaturated polyethers, mercapto, amino- or alkoxy-modified epoxy acrylates, mercapto, amino- or alkoxy-modified epoxy resins, mercapto, amino- or alkoxy-modified (meth) acrylic acid, mercapto, amino - Or alkoxy-modified (meth) acrylic acid esters, mercapto-, amino- or alkoxy-modified polyester acrylates, mercapto-, amino- or alkoxy-modified polyether acrylates, mercapto-, amino- or alkoxy-modified polyurethanes, mercapto-, amino- or alkoxy -modified polyurethane acrylates, mercapto-, amino- or alkoxy-modified glycidyl (meth) acrylates, mercapto-, amino- or alkoxy-modified acrylate resins, mercapto-, amine o- or alkoxy-modified polydialkylsilanes with terminal silanol groups, mercapto-, amino- or alkoxy-modified hydroxyalkyl acrylates, mercapto-, amino- or alkoxy-modified polydialkylsilanes with terminal epoxy groups, alkoxylated

Trimethylolpropane triacrylate and mixtures thereof are suitable. It has been found to be particularly advantageous if the molar ratio of functional group of which is a hydrogen atom in a reaction with a radical

is split off homolytically, to a functional group which leads to a polymerization reaction by means of UV-A radiation, is from 1: 100 to 10: 1, in particular from 1:20 to 1: 1. One advantage of this embodiment of the method according to the invention is that particularly uniform curing can be achieved.

In a further preferred embodiment of the method according to the invention, at least two compounds are combined with one another as binders, wherein the first compound polymerizes by means of UV-A radiation and the second compound contains a functional group from which a hydrogen atom is homolytically split off in a reaction with a radical. Experimental studies have shown that particularly uniform and complete curing is achieved if the first compound is selected from the group consisting of unsaturated esters, unsaturated polyesters, unsaturated ethers, unsaturated polyethers, epoxy acrylates, epoxy resins, (meth) acrylic acid, (meth ) Acrylic acid esters,

Polyester acrylates, polyether acrylates, polyurethanes, polyurethane acrylates,

Glycidyl (meth) acrylates, unsaturated acrylate resins, polydialkylsilanes with terminal silanol groups, hydroxyalkyl acrylates, polydialkylsilanes with terminal

Epoxy groups, alkoxylated trimethylolpropane triacrylate and mixtures thereof and the second compound contains a thiol, amine and / or ether group.

It is particularly advantageous if the second compound is selected from the group consisting of pentaerythritol tetrakis (3-mercaptopropionate), 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol, trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3 mercaptoacetate),

Trimethylolpropane tris (3-mercaptoacetate), 4-t-butyl-1,2-benzenedithiol, bis- (2-mercaptoethyl) sulfide, 4,4'-thiodibenzenethiol, benzenedithiol, glycol dimercaptoacetate, glycol dimercaptopropionate ethylene bis (3-mercaptopropionate),

Polyethylene glycol dimercaptoacetate, polyethylene glycol di (3-mercaptopropionate), pentaerythritol tetrakis (3-mercapto-propionate), mercapto-methyltetrahydrothiophene, tris- (3-mercaptopropyl) isocyanurate, 2-mercaptoethylsulfide (1,2,3- mercaptomercethylsulfide, 1,2,3-mercaptomercethyl-trimethyl) ) -1,3-propanedithiol, dipentaerythrithiol, 1,2,4-trimercaptomethylbenzene, 2,5-dimercaptomethyl-1,4-dithiane,

Bisphenofluorenbis (ethoxy-3-mercaptoproprionate), 4,8-bis (mercaptomethyl) -3,6,9-trithia-l, ll-undecanedithiol, 2-mercaptomethyl-2-methyl-l, 3-propanedithiol, 1,8- Dimercapto-3,6-dioxaoctane, thioglycerol bismercapto-acetate, allyl ethers, benzyl ethers and mixtures thereof. A particularly smooth and non-adhesive surface is achieved by using pentaerythritol tetrakis (3-mercaptopropionate) as the second connection. The combination of ethoxylated trimethylolpropane triacrylate is the first to produce a particularly homogeneous, deep-hardening glaze Compound and pentaerythritol tetrakis (3-mercaptopropionate) achieved as the second compound. According to this preferred embodiment of the invention, the ratio of first to second compound can be selected within a wide range, a weight ratio of first to second compound of 65:35 to 95: 5, in particular from 70:30 to 90:10, being particularly advantageous

has turned out.

In order to ensure complete hardening and good applicability of the glaze on the surface, the glaze contains 5 to 60% by weight of reactive thinner. Particularly good flow and curing properties can be achieved if the UV-curing glaze is from 10 to 50% by weight, preferably from 15 to 45% by weight, preferably from 20 to 40% by weight, more preferably from 25 to 38% by weight. % or most preferably from 28 to 35% by weight, each based on the total weight of the glaze,

Contains reactive thinner. A reactive diluent content of less than 5% by weight leads to poor flow behavior and impaired applicability of the glaze. A reactive thinner content of more than 60% by weight, on the other hand, leads to poor adhesion of the glaze to the surface and increased adhesion

Smearability of the glaze.

The reactive thinner in the glaze serves, on the one hand, to create the right ones

To achieve the flow properties of the glaze, on the other hand, the reactive thinner serves to ensure uniform curing of the glaze. It has been found that the reactive thinner solves these tasks particularly well when the reactive thinner is selected from the UV-curing glaze

Monoacrylsäureestern, in particular octyl acrylate, decyl acrylate, phenoxyethyl acrylate, Norbonylacrylat, dicyclopentadienyl acrylate, polyfunctional Acrylestern of polyalcohols, in particular hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, Acrylester of polyfunctional polyether alcohols, in particular diethylene glycol acrylate, dipropylene glycol diacrylate, acrylate of ethoxylated glycerol, acrylate of trimethylolpropane, acrylate of di-trimethylol propane , Acrylic acid ester of pentaerythritol, Acrylic acid esters of dipentaerythritol, vinyl ethers, in particular

Diethylene glycol vinyl ether, triethylene glycol divinyl ether,

3-methacryloxypropyltrimethoxysilane or N-vinyl compounds, in particular N-vinylpyrrolidone, N-vinylimidazole, N-vinylcaprolactam, and mixtures thereof.

It has been found that particularly good flow and

Let the glaze achieve reaction properties if two or more

different reactive thinners can be combined with one another. Oxybis (methyl-2, l-ethanediyl) diacrylate and / or 1,1,1-trihydroxymethylpropyl triacrylate have proven to be particularly suitable reactive diluents for the glaze according to the method according to the invention. If the glaze used in the process according to the invention contains, as a reactive thinner, the combination of oxybis (methyl-2, l-ethanediyl diacrylate (DPGDA) and 1,1,1-trihydroxymethylpropyl triacrylate (TMPTA), which is particularly advantageous for homogeneous hardening of the glaze), this is a ratio of DPGDA and TMPTA from 80:20 to 99: 1, in particular from 90:10 to 95: 5, shown to be particularly advantageous.

So that the curing polymerization of the glaze following the application of the glaze by means of UV-A radiation in step b. the process can take place, the glaze contains 0.1 to 20 wt.% Photoinitiator. It has been shown here that it is ideal for initiating the curing polymerization if the UV-curing glaze is from 0.5 to 15% by weight, preferably from 1 to 10% by weight, or more preferably from 2 to 8% by weight, each based on the total weight of the glaze, contains photoinitiator. With such amounts of photoinitiator, rapid and uniform curing is guaranteed. A photoinitiator content of less than 0.1% by weight leads to an inhomogeneous and sometimes incomplete curing process. A salary

Photoinitiator greater than 20% by weight does not lead to any further improvement and, due to the relatively high costs for photoinitiators, leads to a less economical process management. In principle, all photoinitiators known to the person skilled in the art are suitable for coatings for the process according to the invention. A particularly homogeneous glaze can be obtained if the photoinitiator of the UV-curing glaze is selected from diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L) , Phenyl bis (2,4,6-trimethylbenzoyl) - phosphine oxide, l- [4- (4-benzoylphenylsulfanyl) phenyl) -2-methyl-2- (4-methylphenylsulfonyl) propan-l-one, 2-hydroxy- 2-methyl-l-phenylpropanone, 2- isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone,

difunctional ketosulfone, 4,4'-bis (diethylamino) benzophenone, benzil dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, α-aminophenyl ketone, bisbenzyolphosphine oxide, 2-morpholin-N-yl-2-2 (4-methylthiobenzoyl) propane, 2-hydroxy-2 benzoyl propane, 1-hydroxycyclohexyl phenyl ketone, benzoin ether, benzil, and mixtures thereof. Experimental studies have shown that the combination of a phosphine oxide photoinitiator, such as TPO, TPO-L or phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide with 1- [4- (4-benzoylphenylsulfanyl) phenyl) -2-methyl-2- (4-methylphenylsulfonyl) propan-l-one is particularly suitable for use in the process according to the invention. With this combination of photoinitiators, particularly homogeneous curing is achieved. In addition, with the preferred photoinitiators it can be ensured that the UV-curing glaze does not show any yellowing during and / or after curing. The ratio of the combination of phosphine oxide photoinitiator to 1- [4- (4-benzoylphenylsulfanyl) phenyl) -2-methyl-2- (4-methylphenylsulfonyl) propan-1-one is from 30:70 to 70:30 ,

in particular from 40:60 to 60:40 or from about 50:50, turns out to be particularly advantageous for uniform curing.

Depending on the area of application of the glaze, the requirements for the optical appearance of the glaze can vary. According to one embodiment of the invention, pigments and / or matting agents can be used in the UV-curing glaze in order to achieve certain optical properties. According to a preferred embodiment of the method according to the invention, the UV-curing glaze contains 0.1 to 15% by weight, based on the total weight of the glaze, organic and / or inorganic pigments, the glaze also with the organic and / or inorganic pigments having a hiding power of a maximum of 90% at 50 ml / m ² , measured in accordance with standard EN ISO 6504-3: 2007, in particular EN ISO 6504-3: 2007, on black and white Cards raised, has. By adding “transparent” pigments, a particularly appealing and high-quality appearance can be achieved.

Transparent iron oxide pigments have proven particularly suitable here

exposed. Transparent iron oxide pigments are

Iron oxide pigments with an average particle size of less than 0.1 gm,

in particular less than 0.05 gm or 0.01 gm, which due to their size are permeable to visible light or pigments with a specific BET surface area of more than 80 m ² / g. Pigments with a specific BET surface area of 100 m ² / g are referred to as highly transparent. Processes for the production of such transparent iron oxide pigments are described in EP 0 704 499 B1 and EP 0 704 499 B1

EP 0 704 501 A1 can be found.

Methods for determining the particle size are known to the person skilled in the art.

For example, the maximum particle size can be determined using a grindometer according to DIN EN ISO 1524, in particular according to DIN EN ISO 1524: 2013-06. The mean particle size can in particular denote the D 50 value. The D 50 value can in particular denote the size at which 50%, for example 50% by weight, are smaller than the specified size. For example, 50%, for example 50% by weight, of the particles would then pass through a theoretical mesh size. Methods for determining the mean particle size, in particular the D 50 value, are known to the person skilled in the art. The mean particle size, in particular the D 50 value, can be determined, for example, by creating a particle size distribution. The measurement can be carried out, for example, by means of light scattering, in particular by means of laser diffractometry or photon correlation spectroscopy. In particular, the mean particle size, in particular the D 50 value, can be measured in a liquid medium, for example an aqueous medium. The measurement can in particular in accordance with ISO 13321, in particular IS013321: 1996, and / or ISO 22412, in particular ISO 22412: 2008. For example, a Malvern Mastersizer 2000 or 3000 can be used to determine the mean particle size, in particular the D 50 value. Further possibilities for determining the mean particle size, in particular the Dso value, are light and / or laser diffraction. Furthermore, the mean particle size, in particular the Dso value, can be determined with the aid of an ultracentrifuge or with chromatographic

Methods, for example the Capillary Hydrodynamic Fractionation (CHDF) can be determined.

The BET surface area can be determined according to the ISO 9277 standard, in particular according to the ISO 9277: 2010 standard, by means of gas adsorption.

According to one embodiment, inorganic pigments are preferred as pigments

Pigments used. Examples of inorganic pigments are oxides such as titanium dioxide, iron oxides, e.g. P.Y. 42, P.R. 101, P.Bk. 11, chrome oxide green, e.g. P.G. 17,

Chromium oxides, e.g. P.Br. 29, mixed phase pigments e.g. Cobalt Oxides Blue P.B. 28 and Green P.G. 50, bismuth vanadate P.Y. 184, rutile-tin-zinc P.O. 216, rutile-tin-zinc-titanium P.Y. 213, silicates, e.g. Ultramarine blue P.B. 29 and carbon, e.g. Soot P.Bk. 7th

According to a further embodiment, organic pigments are preferably used as pigments. Examples of organic pigments are azo pigments, e.g.

Aiylid Yellow (Monoazo) P.Y. 74, polycyclic pigments, e.g. Quinacridones P.R. 122, Perinone P.O. 43, pyrazolo-quinazolone P.O. 67, diketo-pyrrolo-pyrrole (DPP) P.R. 254, Dioxazine P.V. 23 and metal complex pigments, e.g. Copper Phthalocyanine Blue P.B. 15: 3 and Green P.G. 7th

The names of the inorganic and organic pigments used above correspond to the Generic Names of the Color Index of the British Society of Dyers and Colourists. According to a further preferred embodiment of the invention, the UV-curing glaze contains 0.1 to 20% by weight, in particular 1 to 15% by weight or 3 to 12% by weight, in each case based on the total weight of the glaze, matting agent. In this way, a glaze with a particularly attractive, homogeneous gloss level can be obtained. Matting agents selected from silicon dioxide, micronized polypropylene wax coated with silica, silicas, silicates, polyethylene, polypropylene and copolymers or mixtures thereof have proven to be particularly suitable for creating a velvety appearance. If, on the other hand, the use of matting agents is dispensed with, a particularly shiny glaze can be obtained.

In principle, the UV-curing glaze used in the method according to the invention already has a good shelf life or shelf life. However, this can be increased even further if the UV-curing glaze contains 0.01 to 3% by weight of inhibitor, based in each case on the total weight of the glaze. The inhibitor prevents unwanted partial polymerization of the binder and / or the reactive diluent and in this way increases the shelf life and storage stability of the glaze. According to a preferred embodiment of the invention, the glaze contains a larger amount of photoinitiator than inhibitor, in particular at least 0.5 or at least 1% by weight more photoinitiator than inhibitor, based on the total weight of the glaze. This ensures that the inhibitor does not interfere with the curing polymerization.

According to a further preferred embodiment, the UV-curing glaze is essentially free of volatile organic solvents which have a boiling point of below 240 ° C. at 1013 mbar. The UV-curing glaze is particularly preferably essentially free of one or more volatile organic compounds

Solvents selected from the group consisting of special boiling point petrol, solvent petrol, white spirit, tetralin, decalin, gum turpentine oil, root turpentine oil, pine oil, benzene, toluene, xylene, cumene, trimethylbenzene

Tetramethylbenzene, diethylbenzene, methylene chloride, chloroform, carbon tetrachloride, Ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone,

Cyclohexanone, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methoxypropanol, methoxypropyl acetate, 1,2-propanediol, butyl glycol,

Diacetone alcohol, dimethylformamide, phenol, cresol, N-methylpyrrolidone,

Dimethyl sulfoxide and mixtures thereof. When we are talking about essentially free of volatile organic solvents, this means in particular that the UV-curing glaze is less than 100 ppm, in particular less than 10 ppm, based on the total weight of the glaze, volatile organic

Contains solvent. If such organic solvents are not used in the UV-curing glaze, the process can be carried out in a particularly environmentally friendly way. In addition, there is increased security for users

guaranteed, as they do not come into contact with harmful solvents.

Methods for determining the boiling point of solvents are known to the person skilled in the art, for example the measurement here is by means of dynamic

Differential scanning calorimetry (DSC) is an option. Alternatively, the boiling point can also be determined, for example, by means of a distillation device.

According to a further preferred embodiment, the UV-curing glaze applied in the method according to the invention is essentially free of water. When we are talking about essentially free of water, this means in particular that the glaze contains less than 1000 ppm, in particular less than 100 ppm or 10 ppm, based on the total weight of the glaze, water. This ensures that no irregularities or drops form in the applied glaze. In addition, this is a particularly good one

Achieved storage stability of the glaze.

The in step a. the process to be applied glaze can also be further, the

Those skilled in the art contain ingredients. So depending on the application the flow properties, optical properties or the miscibility of the glaze can be further improved if the UV-curing glaze at least one of

Contains leveling agents, defoamers, rheological additives, preservatives, deaerators, anti-floating agents or lubricants. Typical representatives of these classes of compounds are known to those skilled in the art. Come as a leveling agent

for example, in particular solutions of a multiacrylic, modified polymethylsiloxane in tripropylene glycol diacrylate in question. Preferred defoamers are hydrocarbons, n-alkanes, cycloalkanes, iso-alkanes, aromatics, mono- and diglycerides, dimethylpolysiloxane and / or silicone oils. The in the course of the

The glaze applied according to the invention preferably contains a total of from 0.01 to 5% by weight, in particular from 0.1 to 2% by weight, based on the

Total weight of the glaze, leveling agent, defoamer, rheological additives,

Preservatives, deaerators, anti-floating agents and / or lubricants.

It is particularly advantageous for the flow properties of the glaze if the glaze is from 0.01 to 0.5% by weight, preferably from 0.05 to 0.2% by weight, based on the

Total weight of the glaze, contains leveling agent. A particularly homogeneous one

Coating that is free from bubbles can be used in the course of the invention

Method can be achieved in particular in that the UV-curing glaze contains from 0.1 to 1% by weight, preferably from 0.3 to 0.7% by weight, based on the total weight of the glaze, defoamers.

According to a preferred embodiment, the process according to the invention comprises process step a. UV-curing glaze to be applied essentially consisting of 20 to 90% by weight of binder, 5 to 60% by weight of reactive thinner, 0.1 to 20% by weight of photoinitiator, each based on the total weight of the glaze. When it is said here that the glaze consists essentially of the components mentioned, this means that the glaze is at least 80% by weight, in particular to

at least 85% by weight or 90% by weight, preferably at least 95% by weight, even more preferably at least 97% by weight, consists of the components mentioned. Up to 20% by weight (or up to 15, 10, 5 or 3% by weight) of the glaze can according to this Embodiment consist of other components, pigments, matting agents, defoamers, leveling agents and / or inhibitors in particular being possible. Such a UV-curing glaze can be cured particularly quickly and inexpensively in the method according to the invention.

Alternatively, in the process according to the invention, there is process step a.

UV-curing glaze to be applied consisting of 20 to 90% by weight of binder, 5 to 60% by weight of reactive thinner, 0.1 to 20% by weight of photoinitiator, each based on the

Total weight of the glaze In this case, the glaze does not contain any other components besides binding agent, reactive thinner and photoinitiator. In this way, objects can be coated in a particularly simple and inexpensive manner.

The process step b. of the method according to the invention relates to the hardening of the in step a. applied glaze using UV-A radiation. In order to be able to carry out this process step directly at the customer, it has proven to be useful in practical studies if the UV-A radiation is used for curing the in step a.

applied glaze is given off by a UV lamp. According to a

preferred embodiment, the UV-A radiation for curing the in step a. applied glaze is emitted by a portable UV lamp. If a UV emitter, in particular a portable UV emitter, is used for curing the glaze in process step b. used, the inventive method can be carried out in a simple manner directly at the customer, the hardening process taking place within a few seconds and thus the entire process

Coating processes at the customer's can be accelerated considerably. With the UV lamp, in particular with the portable UV lamp, the can on a

The glaze applied to the object can be cured evenly and even corners and edges of the object can be easily reached.

When a portable UV lamp is mentioned here or elsewhere, this means a UV lamp that can be carried without great effort by the average user in terms of shape, size and weight and for curing in process step b. of the method according to the invention can be used.

In particular, a portable UV radiator is not a UV radiator that is basically fixed in a stationary manner. The portable UV lamp can also be attached to a suitable tripod.

In this case, a portable UV radiator preferably comprises a handle so that the user can move the portable UV radiator easily.

According to a particularly preferred embodiment of the method according to the invention, the radiation emitted by the UV radiator has at least 90%, preferably at least 95% or particularly preferably at least 97%, based on the total radiation emitted by the UV radiator, a wavelength of more than 315 nm. A UV lamp that has radiation with a wavelength of more than 315 nm to this extent is particularly safe for users. In this way, the user is exposed to almost no short-wave and particularly high-energy UV-B and / or UV-C radiation, which is known as

classified as hazardous to health. In addition, with radiation with a

Wavelength of more than 315 nm ensures particularly even hardening of the glaze over the entire depth.

The in process step b. The UV radiator used preferably has a weight of less than 10 kg, preferably less than 7.5 kg, more preferably less than 5 kg, even more preferably less than 4 kg, more preferably less than 3 kg or particularly preferably from less than 2.5 kg. If the UV lamp has such a weight, it can be easily transported to the customer and can be used flexibly and easily on site.

A particular challenge when coating complex objects with decorations, windings, corners and / or highlights is to ensure that the glaze hardens evenly in the different areas of the

Object to achieve. Practical studies have shown this to be particularly good succeeds if the UV radiator has a radiation exit area of 0.1 to 300 cm ² , preferably 50 to 200 cm ² , more preferably 75 to 150 cm ² or particularly preferably 90 to 110 cm ² . With such a radiation exit surface, areas of an object that are otherwise difficult to access, such as surfaces behind corners or edges, can be completely and uniformly cured.

According to a further preferred embodiment of the method according to the invention, the radiation emitted by the UV radiator has an intensity of 30 to 1000 mW / cm ² , preferably 50 to 500 mW / cm ² or more preferably 100 at a wavelength of 365 nm to 405 nm up to 200 mW / cm ² , each measured at a distance of 20 mm with a surface sensor for UV-A radiation with a spectrum from 340 to 405 nm and with a maximum intensity of 5 W / cm ² . With a UV lamp that has such an intensity at a wavelength of 365 nm to 405 nm, the glaze can be cured particularly evenly.

According to a further embodiment, the UV radiator has an electrical power consumption of 40 to 300 W, preferably 50 to 200 W, preferably 60 to 150 W, more preferably 65 to 100 W, more preferably 68 to 72 W or particularly preferred of about 70 W. With a UV lamp that has such a power consumption, a particularly environmentally friendly and inexpensive process with good and uniform curing of the glaze is possible.

In principle, the described method according to the invention can be carried out on completely different surfaces. Basically, surfaces comprising metal, plastic, wood, glass, ceramics, paper, cardboard, wood chips and / or natural resin are possible. The method according to the invention is particularly suitable for coating surfaces made of wood or wood-based materials, in particular

Wood-based materials based on solid wood (e.g. solid wood, glued wood, glued laminated timber, rod plywood, laminated wood or veneer plywood such as multiplex),

Wood chip materials (e.g. chipboard) or wood fiber materials (e.g. Fibreboard). Visually particularly attractive and well-protecting glazes are obtained according to the method according to the invention if the surface comprises a material made of natural wood and / or a wood look.

In the case of natural wood, it is particularly solid wood, in which the wood can be assigned to a tree species.

Materials made of wood look are materials that are not made entirely of wood, but have a base made of cardboard, wood chip and / or plastic, on which a layer of wood or a layer of another material, which is due to the material or due to a paint finish

or coating has a wood-like appearance, is applied. A surface made of a material with a wood look can consequently also comprise wood.

According to a preferred embodiment, the surface is the surface of a table, a door, a door frame, a worktop, a chest of drawers, a stool, a cupboard, a chair, a shelf, a frame or a piece of furniture. If the surface of such an object is coated by the method according to the invention, the coating is particularly time-efficient and can be carried out directly at the customer's site, which leads to cost savings for the customer.

The invention further provides a system comprising a UV-curing glaze and a UV radiator, the UV-curing glaze, in each case based on the

Total weight of the glaze,

20 to 90% by weight binder,

5 to 60% by weight reactive diluent and

0.1 to 20 wt.% Photoinitiator,

contains and wherein the UV-curing glaze has a viscosity of 10 to 1000 mPa-s at a shear rate of 1000 s ^-1 . Such a system is suitable

excellent for coating surfaces. With the UV lamp, the previously UV-curing glaze applied to a surface is cured directly and

to be edited. Objects can be coated quickly and inexpensively with the system according to the invention.

What has been said in connection with the method according to the invention for UV-curing glaze also applies equally to the UV-curing glaze

system according to the invention.

What has been said in connection with the method according to the invention for the UV radiator also applies equally to the UV radiator of the system according to the invention.

What has been said in connection with the method according to the invention for the surface to be coated applies equally to surfaces that are with the

system according to the invention can be coated.

The invention is furthermore directed to the use of a UV-curing glaze or a system comprising a UV-curing glaze and a UV radiator for coating a surface, the UV-curing glaze in each case based on the total weight of the glaze,

20 to 90% by weight binder,

5 to 60% by weight reactive diluent and

0.1 to 20 wt.% Photoinitiator,

contains and wherein the UV-curing glaze at a shear rate of 1000 s ^-1

Has a viscosity of 10 to 1000 mPa · s.

use according to the invention. What has been said in connection with the method according to the invention for the UV radiator also applies equally to the UV radiator according to the invention

Use.

What has been said in connection with the method according to the invention for the surface to be coated also applies equally to the surface to be coated for the use according to the invention.

In addition, the invention is directed to a UV-curing glaze, the UV-curing glaze, based in each case on the total weight of the glaze,

20 to 90% by weight binder,

5 to 60% by weight reactive diluent and

0.1 to 20 wt.% Photoinitiator,

contains and wherein the UV-curing glaze has a viscosity of 10 to 1000 mPa-s at a shear rate of 1000 s ^-1 .

What has been said in connection with the method according to the invention for UV-curing glaze also applies equally to the UV-curing glaze according to the invention.

The invention is explained in more detail below by means of examples, which, however, only serve the purpose of illustration and are not limiting.

Examples

A matt UV-curing glaze (formulation A) with the following formulation shown in Table 1 was produced by mixing the ingredients given in Table 1, the doses in each case in% by weight:

Table 1

The viscosity of the matt UV-curing glaze was measured using an MCR92 rheometer from Anton Paar ^® at 20 ° C. with a PP50 measuring system (plate geometry;

Diameter 50 mm; Distance 0.5 mm) at a shear rate of 1000 s ^-1 with a shear ramp of 0.01 - 1000 s ^-1 . The viscosity of the matted UV-curing glaze was determined to be 449 mPa · s. The matted UV-curing glaze according to formulation A was good

Shelf life. No increase in viscosity could be observed on storage in the oven for 14 days at 50 ° C.

A part of the matted UV-curing glaze became thin with a usual after mixing on a previously cleaned and sanded table made of solid wood

Paintbrush applied, a glaze with a dry layer thickness of 50 gm was obtained. The glaze was then irradiated with a

UVAHAND LED ^® UV lamps from Hönle AG UV Technology (lamp part weight 1.9 kg) cured. Ten minutes after the layer had hardened, the coated surface was sanded again and a second layer of the matt UV-curing glaze with a dry layer thickness of 50 gm was applied applied and cured with the UVAHAND LED® UV lamp. The coated surface had a velvety soft optical impression and the glaze applied had a high degree of transparency. The entire coating of the table was completed within a period of 2 hours.

Other parts of the matt UV-curing glaze were mixed with different color pigment tinting concentrates from the Brillux Alkyd Tinting Concentrate ^{® range in} order to achieve a specific shade. The formulations are given in Table 2.

Table 2; Quantities in% by weight

The viscosity of the tinted UV-curing glazes pine and rosewood was tested as described above for the matt UV-curing glaze. This resulted in a viscosity of 372 mPa-s for the UV-curing glaze with the shade of pine and a viscosity of 367 mPa-s for the UV-curing glaze with the shade of rosewood. The tinted UV-curing glazes could be used in accordance with the matted UV Apply hardening glaze (formulation A) to objects such as tables and cure quickly.

Another, high-gloss UV-curing glaze (formulation B) with the following formulation shown in Table 3 was produced by mixing the ingredients given in Table 3, the doses in each case in% by weight:

Table 3

The high-gloss UV-curing glaze of formulation B could easily be brushed onto objects in a manner analogous to the matted UV-curing glaze of formulation A and could be cured quickly by means of UV lamps. In this way, articles coated with a high gloss were obtained.

Claims

Patent claims

1. A method for coating a surface at least comprising the steps a. Application of a UV-curing glaze to a surface, the UV-curing glaze, based in each case on the total weight of the glaze, i. 20 to 90% by weight binder,

ii. 5 to 60% by weight reactive diluent and

iii. 0.1 to 20 wt.% Photoinitiator,

contains and wherein the UV-curing glaze has a viscosity of 10 to 1000 mPa-s at a shear rate of 1000 s ^-1 ,

b. Hardening the in step a. applied glaze using UV-A radiation.

2. The method according to claim 1, characterized in that the UV-curing glaze at a shear rate of 1000 s ^{-1 has} a viscosity of 50 to 800 mPa-s, in particular from 100 to 700 mPa-s, from 200 to 600 mPa-s or from 300 to 500 mPa · s.

3. The method according to any one of claims 1 or 2, characterized in that the binder of the UV-curing glaze at a shear rate of 100 s ^{-1 has} a viscosity of 65 to 300 mPa-s, in particular from 70 to 200 mPa-s or of 80 to 150 mPa · s.

4. The method according to any one of the preceding claims, characterized in that the reactive diluent of the UV-curing glaze at a shear rate of 100 s ^{-1 has} a viscosity of 0.1 to 60 mPa-s, in particular from 1 to 40 mPa-s, of 3 to 30 mPa-s or from 5 to 20 mPa-s.

5. The method according to any one of the preceding claims, characterized in that the UV-curing glaze from 30 to 80% by weight, in particular from 35 to 75% by weight, from 40 to 72% by weight or from 45 to 70% by weight contains binding agent, based on the total weight of the glaze.

6. The method according to any one of the preceding claims, characterized in that the binder of the UV-curing glaze contains a compound which comprises at least one functional group from which a hydrogen atom is split off homolytically in a reaction with a radical, the functional group in particular is selected from thiol, amine and ether.

7. The method according to any one of the preceding claims, characterized in that the binder of the UV-curing glaze is a compound selected from the group consisting of unsaturated esters, unsaturated polyesters, unsaturated ethers, unsaturated polyethers, epoxy acrylates, epoxy resins, (meth) acrylic acid, ( Meth) acrylic acid esters, polyester acrylates, polyether acrylates, polyurethanes, polyurethane acrylates, glycidyl (meth) acrylates, unsaturated acrylate resins, polydialkylsilanes with terminal silanol groups,

Hydroxyalkyl acrylates, polydialkylsilanes with terminal epoxy groups, alkoxylated trimethylolpropane triacrylate and mixtures thereof.

8. The method according to any one of the preceding claims, characterized in that the UV-curing glaze from 10 to 50% by weight, in particular from 15 to 45% by weight, from 20 to 40% by weight, from 25 to 38% by weight or from 28 to 35% by weight, based in each case on the total weight of the glaze, contains reactive thinner.

9. The method according to any one of the preceding claims, characterized in that the reactive diluent of the UV-curing glaze is selected from

Monoacrylic acid esters, especially octyl acrylate, decyl acrylate,

Phenoxyethyl acrylate, norbonylacrylate, dicyclopentadienyl acrylate,

polyfunctional acrylic esters of polyalcohols, in particular Hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, acrylic esters of multifunctional polyether alcohols, in particular diethylene glycol acrylate, dipropylene glycol diacrylate, acrylic acid esters of ethoxylated glycerol, acrylic acid esters of trimethylol propane

Acrylic acid esters of di-trimethylolpropane, acrylic acid esters of pentaerythritol, acrylic acid esters of dipentaerythritol, vinyl ethers, in particular

Diethylene glycol vinyl ether, triethylene glycol divinyl ether or N-vinyl compounds, in particular N-vinylpyrrolidone, N-vinylimidazole, N-vinylcaprolactam, and mixtures thereof.

10. The method according to any one of the preceding claims, characterized in that the UV-curing glaze from 0.5 to 15% by weight, in particular from 1 to 10% by weight or from 2 to 8% by weight, based in each case on the total weight contains the glaze, photoinitiator.

11. The method according to any one of the preceding claims, characterized in that the photoinitiator of the UV-curing glaze is selected from

Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, ethyl (2,4,6-trimethylbenzoylphenylphosphinate, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, 1- [4- (4-benzoylphenylsulfanyl) phenyl) - 2-methyl-2- (4-methylphenylsulfonyl) propan-l-one, 2-hydroxy-2-methyl-l-phenylpropanone, 2- isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, difunctional ketosulphone, 4,4 ' -bis (diethylamino) benzophenone,

Benzil dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, α-aminophenyl ketone, bisbenzyolphosphine oxide, 2-morpholin-N-yl-2-2 (4-methylthiobenzoyl) propane, 2-hydroxy-2-benzoylpropane, 1-hydroxycyclohexylphenyl benzene and mixtures thereof, benzoin ethers.

12. The method according to any one of the preceding claims, characterized in that the UV-curing glaze contains 0.1 to 15% by weight, based on the total weight of the glaze, organic and / or inorganic pigments.

13. The method according to any one of the preceding claims, characterized in that the UV-curing glaze 0.1 to 20 wt.%, In particular 1 to 15 wt.% Or 3 to 12 wt.%, Each based on the total weight of the glaze,

Contains matting agent, the matting agent being selected in particular from silicon dioxide, micronized polypropylene wax coated with silica, silicas, silicates, polyethylene, polypropylene, copolymers and

Mixtures thereof.

14. The method according to any one of the preceding claims, characterized in that the UV-curing glaze contains 0.01 to 3 wt -Methoxyphenol, 4-methoxyphenol,

Butylated hydroxytoluene, hydroquinone, benzophenones, benzotriazoles and mixtures thereof.

15. The method according to any one of the preceding claims, characterized in that the UV-curing glaze is essentially free of organic

Solvents that have a boiling point of up to 240 ° C at 1013 mbar.

16. The method according to any one of the preceding claims, characterized in that the UV-curing glaze contains at least one of leveling agents, defoamers, rheological additives, preservatives, deaerators, anti-floating agents or lubricants.

17. The method according to any one of the preceding claims, characterized in that the UV-A radiation for curing the in step a. applied glaze is given off by a UV lamp, in particular a portable UV lamp.

18. The method according to claim 17, characterized in that the radiation emitted by the UV emitter has at least 90%, in particular at least 95% or at least 97%, based on the total radiation emitted by the UV emitter, a wavelength of more than 315 nm.

19. The method according to any one of claims 17 or 18, characterized in that the UV radiator has a weight of less than 10 kg, in particular less than 7.5 kg, less than 5 kg, less than 4 kg, or less than 3 kg less than 2.5 kg.

20. The method according to any one of claims 17 to 19, characterized in that the UV radiator has a radiation exit area of 0.1 to 300 cm ² , in particular from 50 to 200 cm ² , from 75 to 150 cm ² or from 90 to 110 cm ² .

21. The method according to any one of claims 17 to 20, characterized in that the radiation emitted by the UV radiator at a wavelength of 365 nm to 405 nm has an intensity of 30 to 1000 mW / cm ² , in particular from 50 to 500 mW / cm ² or 100 to 200 mW / cm ² , each at a distance of 20 mm with a

Area sensor for UV-A radiation with a spectrum from 340 to 405 nm and measured with a maximum intensity of 5 W / cm ² .

22. The method according to any one of claims 17 to 21, characterized in that the UV radiator has an electrical power consumption of 40 to 300 W, in particular from 50 to 200 W or from 60 to 150 W or from 65 to 100 W or from 68 to 72 W or about 70 W.

23. The method according to any one of the preceding claims, characterized in that the surface comprises a material made of natural wood and / or wood look.

24. The method according to any one of the preceding claims, characterized in that it is the surface of a table, a door, a A door frame, a worktop, a chest of drawers, a stool, a cupboard, a chair, a shelf, a frame or a piece of furniture.

25. System comprising a UV-curing glaze and a UV radiator, the UV-curing glaze as defined in one of claims 1 to 16 and the UV radiator as defined in one of claims 17 to 22.

26. Use of a UV-curing glaze, which is as defined in one of claims 1 to 16, or a system according to claim 25 for coating a surface.

27. Use according to claim 26, characterized in that the surface is defined as in one of claims 23 to 24.

28. UV-curing glaze, wherein the UV-curing glaze is as defined in one of claims 1 to 16.