EP3046778B2 - Thermo transfer films for the dry lacquering of surfaces - Google Patents

Description

The present invention relates to thermal transfer foils and their use for the dry coating of surfaces. The invention also relates to the production of such thermal transfer foils and a method for coating or varnishing surfaces of objects using the thermal transfer foils according to the invention.

The surfaces of objects are usually coated using the wet paint process, i. H. a liquid paint is applied to the surface to be coated and then dried, creating a layer of paint on the surface. In the case of industrial painting, painting usually takes place in painting lines, with longer drying lines regularly being necessary for drying, during which the paint is dried and cured with a comparatively high expenditure of energy. Such methods are therefore time-, energy- and personnel-intensive. In addition, after the painting is finished, the coating devices of the painting lines have to be cleaned, which leads to downtimes. In addition, the waste generated when cleaning the machines must be disposed of as hazardous waste. Some two-component paints have a limited pot life and any unused residue must also be disposed of as hazardous waste.

There have been various reports of coating or painting techniques in which one or more layers of paint are transferred to the surface to be coated using hot stamping foils, also referred to as thermal transfer foils. These films comprise a carrier film on which one or more polymer layers and optionally an adhesive layer are arranged. During coating, the at least one polymer layer is transferred from the carrier film to the surface to be coated by means of pressure and/or heat. In this way, the at least one polymer layer forms a lacquer layer on the surface to be coated without organic solvents having to be used in the coating process. By combining decorative and lacquer layers, a wide variety of surface designs can be achieved in a very simple and reproducible manner.

the EP 573676 describes a method for applying a lacquer with colored decoration to a substrate, for example on wood or plastic surfaces, in which a film is used which has a decorative layer applied to a carrier with release properties and a partially crosslinked lacquer layer applied to the decorative layer. The film is applied to the surface to be coated with the paint layer and transferred to the surface with the decorative layer by pressure and elevated temperature, with the paint layer curing at the same time. Thermally curable lacquers are used as lacquers. Due to the high temperatures required in the paint curing process, the selection of substrates is severely restricted.
Out of EP1702767 thermal transfer foils are known which have a decorative layer arranged on a carrier layer and a heat-activatable adhesive layer arranged on the decorative layer, the carrier layer having a metallic functional layer lying directly on the decorative layer, which facilitates the detachment of the decorative layer from the carrier layer and thus improves the transfer of the Decorative layer should ensure on the substrate. The metallization limits the decorative layer.

the EP1970215 in turn describes thermal transfer films suitable for the coating of surfaces, which have a base lacquer layer connected to a carrier film and also functioning as a separating layer, a colored decorative layer and a transfer layer with an adhesive effect, the layers being based on aqueous coating systems which contain heat-drying aqueous polymer dispersions as binders. The surface hardness and abrasion resistance of the coatings obtained are often unsatisfactory. Highly abrasion-resistant coatings cannot be obtained with the thermal transfer films described there. EP-A-0 210 620 describes a method for producing a film having a textured lacquer layer. the EP2078618 describes thermal transfer films which have at least one topcoat layer arranged on a carrier film and a thermally activatable adhesive layer, the topcoat layer preferably being based on an aqueous coating composition which contains a dispersed polyurethane which is curable by UV radiation. It is true that the thermal transfer foils described there lead to improved surface hardness in comparison with thermal transfer foils whose lacquer layers are based on heat-drying aqueous polymer dispersions. However, this is not satisfactory for some applications. In addition, the use of aqueous coating agents is associated with an increased drying effort in the production of the thermal transfer foils. The coatings described there are not always satisfactory in terms of abrasion resistance and surface properties. Highly abrasion-resistant coatings cannot be obtained with the thermal transfer films described there.

Surprisingly, it has been found that thermal transfer films which have at least one coating layer arranged on the carrier film and which is based on a non-aqueous, radiation-curable, liquid composition which contains at least 60% by weight, in particular at least 70% by weight, based on the total weight the composition containing crosslinkable components selected from organic oligomers containing ethylenically unsaturated double bonds and mixtures of these oligomers with monomers containing at least one ethylenically unsaturated double bond and having a heat-sealable polymeric adhesive layer (4) containing at least one UV contains radiation-curable component and is based on at least two aqueous polymer dispersions, at least one polymer dispersion containing a UV-curable polymer in dispersed form and at least one further polymer dispersion containing a self-crosslinking polymer in dispe contains rged form, are particularly suitable for coating surfaces. The use of such thermal transfer foils leads to particularly resistant surfaces that adhere particularly well to the coated substrates. In addition, the use of non-aqueous, radiation-curable coating compositions with a high proportion of crosslinkable components allows the targeted adaptation of the thermal transfer film for different substrates, namely for both hard and highly elastic substrates. In contrast to thermal transfer foils with lacquer layers based on thermally curable coating agents, the temperature load on the material to be coated during the transfer of the lacquer layer(s) to the surface to be coated is comparatively low, since final curing can easily be carried out by irradiating the coated surface with UV radiation and no subsequent tempering is necessary.

Due to the use of liquid compositions with a high proportion of crosslinkable components, which are cured by high-energy radiation, in particular by UV radiation, long drying times can also be omitted in the production of the thermal transfer foils, so that their production can be carried out very efficiently.

1. a) eine Trägerfolie (2),
2. b) wenigstens eine, z. B. ein, zwei oder drei, unmittelbar auf der Trägerfolie (2) angeordnete Lackschicht(en) (3),
3. c) wenigstens eine, insbesondere genau eine heißsiegelbare, polymere Klebeschicht (4),

• wobei die Lackschicht auf einer nicht-wässrigen, strahlungshärtbaren, flüssigen Zusammensetzung basiert, die wenigstens 60 Gew.-%, insbesondere wenigstens 70 Gew.-%, bezogen auf das Gesamtgewicht der Zusammensetzung, härtbare Bestandteile enthält, die ausgewählt sind unter organischen Oligomeren, die ethylenisch ungesättigte Doppelbindungen aufweisen und Gemischen dieser Oligomere mit Monomeren, die wenigstens eine ethylenisch ungesättigte Doppelbindung aufweisen und wobei die heißsiegelbare polymere Klebeschicht (4) wenigstens einen strahlungshärtbaren Bestandteil enthält, der ausgewählt ist unter organischen Oligomeren und Polymeren, die ethylenisch ungesättigte Doppelbindungen aufweisen,
• wobei die Klebeschicht (4) auf wenigstens zwei wässrigen Polymerdispersionen basiert, wobei wenigstens eine Polymerdispersion ein durch UV-Strahlung härtbares Polymer in dispergierter Form enthält und wobei wenigstens eine weitere Polymerdispersion ein selbstvernetzendes Polymer in dispergierter Form enthält.

Die Erfindung betrifft auch die Herstellung der erfindungsgemäßen Thermotransferfolien, welche die folgenden Schritte umfasst:

1. i. das Aufbringen der nicht-wässrigen, strahlungshärtbaren, flüssigen Zusammensetzung, wobei man eine durch energiereiche Strahlung härtbare Beschichtung erhält;
2. ii. Bestrahlung der in Schritt i. erhaltenen härtbaren Beschichtung mit energiereicher Strahlung, insbesondere mit UV-Licht, wobei man die Lackschicht (3) erhält;
3. iii. gegebenenfalls Aufbringen einer Dekorschicht auf die härtbare Beschichtung oder auf die Lackschicht (3); und
4. iv. Aufbringen der heißsiegelbaren, polymeren Klebeschicht (4).

Ein weiterer Gegenstand der Erfindung ist die Verwendung der erfindungsgemäßen Thermotransferfolien zur Trockenlackierung von Gegenständen.
Gegenstand der Erfindung ist auch ein Verfahren zum Beschichten von Oberflächen von Gegenständen, umfassend die folgenden Schritte:

1. a) Aufbringen der erfindungsgemäßen Thermotransferfolie (1) mit der Klebeschicht auf die zu beschichtende Oberfläche;
2. b) Heißsiegeln der Transferfolie, wobei man eine mit der Transferfolie beschichtete Oberfläche erhält;
3. c) Bestrahlung der mit der Transferfolie beschichteten Oberfläche mit energiereicher Strahlung, insbesondere mit UV- oder Elektronenstrahlung, speziell mit UV-Strahlung; und
4. d) gegebenenfalls Ablösen der Trägerfolie (2).

Die erfindungsgemäßen Thermotransferfolien weisen wenigstens eine Lackschicht auf, die auf einer nicht-wässrigen, strahlungshärtbaren, flüssigen Zusammensetzung basiert. Hierunter versteht man, dass die Lackschicht bzw. die Lackschichten durch Härtung einer oder mehrerer Schichten der flüssigen strahlungshärtbaren Zusammensetzung durch Bestrahlung mit energiereicher Strahlung, insbesondere mit UV-Strahlung, erhalten werden. Anders als bei Lackschichten auf Basis wässriger Beschichtungsmittel mit strahlungshärtbaren Bindemitteln weisen die erfindungsgemäßen Lackschichten, die unter Verwendung nicht-wässriger, strahlungshärtbarer, flüssiger Zusammensetzungen hergestellt werden, eine gleichmäßigere Struktur und Vernetzung innerhalb der Lackschicht und weniger Fehlstellen auf. Dies ist vermutlich darauf zurückzuführen, dass anders als in den wässrigen Beschichtungsmitteln, die härtbaren, d. h. polymerisierbaren, Bestandteile in der noch ungehärteten Beschichtung eine kohärente Phase bilden, so dass sich die kovalenten Bindungen, welche beim Bestrahlen zwischen den härtbaren Bestandteilen der Zusammensetzung gebildet werden, gleichmäßig innerhalb der Schicht ausbilden können.Accordingly, a first subject matter of the present invention relates to a thermal transfer film (1), comprising:

1. a) a carrier film (2),
2. b) at least one, e.g. B. one, two or three lacquer layer(s) (3) arranged directly on the carrier film (2),
3. c) at least one, in particular precisely one, heat-sealable polymeric adhesive layer (4),

• wherein the lacquer layer is based on a non-aqueous, radiation-curable, liquid composition which contains at least 60% by weight, in particular at least 70% by weight, based on the total weight of the composition, of curable components which are selected from organic oligomers which have ethylenically unsaturated double bonds and mixtures of these oligomers with monomers which have at least one ethylenically unsaturated double bond and wherein the heat-sealable polymeric adhesive layer (4) contains at least one radiation-curable component selected from organic oligomers and polymers which have ethylenically unsaturated double bonds,
• wherein the adhesive layer (4) is based on at least two aqueous polymer dispersions, wherein at least one polymer dispersion contains a UV-curable polymer in dispersed form and wherein at least one further polymer dispersion contains a self-crosslinking polymer in dispersed form.

The invention also relates to the production of the thermal transfer films according to the invention, which comprises the following steps:

1. i. applying the non-aqueous radiation-curable liquid composition to obtain an energetic radiation-curable coating;
2. ii. Irradiation of the in step i. curable coating obtained with high-energy radiation, in particular with UV light, the lacquer layer (3) being obtained;
3. iii. optionally applying a decorative layer to the curable coating or to the lacquer layer (3); and
4. IV. Application of the heat-sealable, polymeric adhesive layer (4).

A further object of the invention is the use of the thermal transfer films according to the invention for the dry coating of objects.
The invention also relates to a method for coating surfaces of objects, comprising the following steps:

1. a) applying the thermal transfer film (1) according to the invention with the adhesive layer to the surface to be coated;
2. b) heat sealing the transfer film to obtain a transfer film coated surface;
3. c) irradiation of the surface coated with the transfer film with high-energy radiation, in particular with UV or electron beams, especially with UV radiation; and
4. d) optionally detaching the carrier film (2).

The thermal transfer films according to the invention have at least one lacquer layer which is based on a non-aqueous, radiation-curable, liquid composition. This means that the lacquer layer or lacquer layers are obtained by curing one or more layers of the liquid radiation-curable composition by irradiation with high-energy radiation, in particular with UV radiation. Unlike paint layers based on water-based coating agents with radiation-curable binders, the lacquer layers according to the invention, which are produced using non-aqueous, radiation-curable, liquid compositions, have a more uniform structure and crosslinking within the lacquer layer and fewer defects. This is probably due to the fact that, unlike in aqueous coating compositions, the curable, ie polymerizable, components form a coherent phase in the still uncured coating, so that the covalent bonds formed between the curable components of the composition on irradiation can form evenly within the layer.

The radiation-curable, liquid compositions used to produce the lacquer layer contain at least 60% by weight, in particular at least 70% by weight, e.g. B. 60 to 99% by weight, in particular 70 to 95% by weight, based on the total weight of the composition, of curable components which have ethylenically unsaturated double bonds. Here, the components are preferably selected such that the composition contains 1.5 to 8 mol, in particular 2.0 to 7 mol and especially 2.5 to 6.5 mol of ethylenically unsaturated double bonds per kg of the coating composition.

The ethylenically unsaturated double bonds of the curable components of the liquid, radiation-curable composition which forms the coating layer are preferably in the form of acrylic groups, methacrylic groups, allyl groups, fumaric acid groups, maleic acid groups and/or maleic anhydride groups, in particular at least 90% or 100%, based on the total amount of the ethylenically unsaturated double bonds contained in the composition, in the form of acrylic or methacrylic groups and especially in the form of acrylic groups. The acrylic and methacrylic groups may be in the form of (meth)acrylamide or (meth)acrylate groups, with the latter being preferred. In particular, at least 90% or 100%, based on the total amount of the ethylenically unsaturated double bonds present in the composition, of the curable components of the radiation-curable composition which forms the lacquer layer have acrylate groups.

According to the invention, the liquid, radiation-curable compositions which are used to produce the coating layer contain at least one oligomer which has ethylenically unsaturated double bonds. The oligomers preferably have an average functionality in the range from 1.5 to 10, in particular in the range from 2 to 8.5, i. H. the number of ethylenically unsaturated double bonds per molecule is on average in the range from 1.5 to 10 and in particular in the range from 2 to 8.5. Mixtures of different oligomers with different functionality are also suitable, the average functionality preferably being in the range from 1.5 to 10, in particular in the range from 2 to 8.5.

The oligomers typically have a linear or branched basic structure which carries on average more than one ethylenically unsaturated double bond, preferably in the form of the aforementioned acrylic groups, methacrylic groups, allyl groups, fumaric acid groups, maleic acid groups and/or maleic anhydride groups, in particular in the form of acrylic or methacrylic groups, where the ethylenically unsaturated double bonds can be bonded to the basic structure via a linker or are part of the basic structure. Suitable oligomers are primarily oligomers from the group of polyethers, polyesters, polyurethanes and epoxide-based oligomers. Preference is given to oligomers which have essentially no aromatic structural units and mixtures of oligomers with aromatic groups and oligomers without aromatic groups.

In particular, the oligomers are selected from polyether (meth)acrylates, i. H. Polyethers with acrylic or methacrylic groups, polyester (meth)acrylates, d. H. Polyesters with acrylic or methacrylic groups, epoxy (meth)acrylates, d. H. Reaction products of polyepoxides with hydroxyl-functionalized acrylic or methacrylic compounds, urethane (meth)acrylates, i. H. Oligomers which have a (poly)urethane skeleton and acrylic or methacrylic groups, for example reaction products of polyisocyanates with hydroxyl-functionalized acrylic or methacrylic compounds, and unsaturated polyester resins, d. H. Polyesters which have several ethylenically unsaturated double bonds, preferably present in the polymer backbone, e.g. B. condensation products of maleic acid or fumaric acid with aliphatic diols or polyols, and mixtures thereof.

In contrast to the monomers, which can also be contained in these curable compositions, the oligomers typically have a molecular weight (number average) of at least 400 g/mol, in particular at least 500 g/mol, e.g. B. in the range of 400 to 4000 g / mol and in particular in the range of 500 to 2000 g / mol. In contrast, the monomers typically have molecular weights below 400 g/mol, e.g. B. in the range of 100 to <400 g / mol.

Suitable polyether (meth)acrylates are primarily aliphatic polyethers, especially poly(C ₂ -C ₄ )-alkylene ethers, which have on average 2 to 4 acrylate or methacrylate groups. Examples of these are the Laromer® grades ^PO33F , LR8863, GPTA, LR8967, LR8962, LR9007 from BASF SE, some of which are mixtures with monomers.

Suitable polyester (meth)acrylates are primarily aliphatic polyesters which have an average of 2 to 6 acrylate or methacrylate groups. Examples of these are the Laromer® grades ^PE55F , PE56F, PE46T, LR9004, PE9024, PE9045, PE44F, LR8800, LR8907, LR9032, PE9074, PE9079, PE9084 from BASF SE, some of which are mixtures with monomers.

Suitable polyurethane acrylates are primarily compounds containing urethane groups which have an average of 2 to 10, in particular 2 to 8.5, acrylate or methacrylate groups and which are preferably obtainable by reacting aromatic or aliphatic di- or oligoisocyanates with hydroxyalkyl acrylates or hydroxyalkyl methacrylates. Examples of these are the ^Laromer® types UA19T, UA9028, UA9030, LR8987, UA9029, UA9033, UA9047, UA9048, UA9050, UA9072, UA9065 and UA9073 from BASF SE, some of which are mixtures with monomers.

In preferred embodiments of the invention, the radiation-curable, liquid composition which forms the lacquer layer comprises at least one oligomer selected from urethane acrylates and polyester acrylates and mixtures thereof, and optionally one or more monomers.

In particular embodiments of the invention, the radiation-curable, liquid composition which forms the lacquer layer comprises at least one urethane acrylate and optionally one or more monomers.

In other particular embodiments of the invention, the radiation-curable, liquid composition which forms the lacquer layer comprises at least one polyester acrylate and optionally one or more monomers.

In specific embodiments of the invention, the radiation-curable, liquid composition that forms the lacquer layer comprises at least one urethane acrylate and at least one polyester acrylate and optionally one or more monomers.

In further specific embodiments of the invention, the radiation-curable, liquid composition which forms the lacquer layer comprises at least one aliphatic urethane acrylate and at least one aromatic urethane acrylate or at least two different aliphatic urethane acrylates and optionally one or more monomers.

In further specific embodiments of the invention, the radiation-curable, liquid composition which forms the lacquer layer comprises at least one aliphatic urethane acrylate, at least one aromatic urethane acrylate and at least one polyester acrylate and optionally one or more monomers.

In addition to the oligomers containing ethylenically unsaturated double bonds, the crosslinkable components of the radiation-curable, liquid composition used to produce the coating layer can contain one or more monomers, which are also referred to as reactive diluents. The monomers typically have molecular weights below 400 g/mol, e.g. B. in the range of 100 to <400 g / mol. Suitable monomers generally have 1 to 6, in particular 2 to 4, ethylenically unsaturated double bonds per molecule. The ethylenically unsaturated double bonds are preferably present in the form of the aforementioned acrylic groups, methacrylic groups, allyl groups, fumaric acid groups, maleic acid groups and/or maleic anhydride groups, in particular in the form of acrylic or methacrylic groups and specifically as acrylate groups.

Preferred monomers are selected from esters of acrylic acid with 1- to 6-hydric, in particular 2- to 4-hydric, aliphatic or cycloaliphatic alcohols, which preferably have 2 to 20 carbon atoms, such as monoesters of acrylic acid with C ₁ -C ₂₀ - alkanols, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, (5-ethyl-1,3-dioxan-5-yl)methanol, phenoxyethanol, 1,4-butanediol or 4-tert-butylcyclohexanol; diesters of acrylic acid with ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol or tripropylene glycol; Triesters of acrylic acid with trimethylolpropane or pentaerythritol and the tetraesters of acrylic acid with pentaerythritol. Examples of suitable monomers are, above all, trimethylolpropane diacrylate, trimethylolpropane triacrylate, ethylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, phenoxyethyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, 4-t-butylcyclohexyl acrylate, 4-hydroxybutyl acrylate and trimethylolformal monoacrylate (acrylic acid-(5-ethyl-1,3- dioxan-5-yl)methyl ester).

In preferred embodiments of the invention, the radiation-curable liquid composition forming the lacquer layer comprises at least one oligomer, e.g. B. 1, 2 or 3 oligomers, in particular at least one, z. 1, 2 or 3 of the oligomers mentioned as preferred and at least one monomer, e.g. B. 1, 2 or 3 monomers, in particular at least one, z. B. 1, 2 or 3, of the monomers mentioned as preferred. In these compositions, the oligomer preferably forms the major part of the curable components of the composition, e.g. H. the oligomer(s) make up at least 50% by weight, in particular at least 60% by weight, based on the total amount of oligomer and monomer. The weight ratio of oligomer to monomer is in particular in the range from 1:1 to 20:1 and especially in the range from 3:2 to 10:1.

In other, likewise preferred embodiments of the invention, the radiation-curable, liquid composition, which is used to produce the lacquer layer, comprises exclusively or almost exclusively, i. H. at least 90% by weight, in particular at least 95% by weight, especially at least 99% by weight, based on the total amount of radiation-curable components of the composition, of one or more oligomers, e.g. B. 2, 3 or 4 oligomers, in particular 2, 3 or 4 of the oligomers mentioned as preferred. The proportion of the monomers is then accordingly at most 10% by weight, in particular at most 5% by weight, especially at most 1% by weight or at 0% by weight, based on the total amount of radiation-curable components of the composition. Such compositions preferably contain at least one polyester acrylate and/or polyurethane acrylate and at least one polyether acrylate.

In addition to the curable components, the radiation-curable, liquid composition used to produce the coating layer generally contains one or more other components, such as photoinitiators, inert fillers, abrasives, flow control agents, coloring components, in particular color pigments, organic solvents and the like. According to the invention, these components make up no more than 40% by weight, in particular no more than 30% by weight, e.g. B. 1 to 40 wt .-%, in particular 5 to 30 wt .-%, based on the total weight of radiation curable liquid composition. The radiation-curable, liquid composition preferably contains no or no more than 10% by weight, based on its total weight, of non-polymerizable volatile components. In this context, volatile constituents are understood to be substances which have a boiling point or an evaporation point below 250° C. at atmospheric pressure, for example organic solvents.

The radiation-curable, liquid composition used to produce the coating layer preferably contains at least one photoinitiator. Photoinitiators are substances which, when exposed to UV radiation, i. H. Light with a wavelength below 420 nm, in particular below 400 nm, decomposes with the formation of free radicals and thus triggers a polymerization of the ethylenically unsaturated double bonds. The radiation-curable, liquid composition preferably contains at least one photoinitiator which has at least one absorption band which has a maximum in the range from 220 to 420 nm, in particular in the range from 240 to 400 nm and which is coupled with the initiation of the decomposition process. The nonaqueous, liquid, radiation-curable composition preferably contains at least one photoinitiator which has at least one absorption band with a maximum in the range from 220 to 420 nm, in particular a maximum in the range from 240 to 400 nm.

Examples of suitable photoinitiators are

• alpha-hydroxyalkylphenones and alpha-dialkoxyacetophenones such as 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl ]phenyl}-2-methylpropan-1-one, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone or 2,2-dimethoxy-1-phenylethanone;
• phenylglyoxalic acid esters such as phenylglyoxalic acid methyl ester;
• Benzophenones such as benzophenone, 2-hydroxybenzophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4-dimethylbenzophenone, 3,4-dimethylbenzophenone, 2,5-dimethylbenzophenone, 4-benzoylbiphenyl, or 4-methoxybenzophenone;
• benzil derivatives such as benzil, 4,4'-dimethylbenzil and benzil dimethyl ketal;
• benzoins such as benzoin, benzoin ethyl ether, benzoin isopropyl ether and benzoin methyl ether;
• acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethoxy(phenyl)phosphoryl-(2,4,6-trimethylphenyl)methanone and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide;
• Titanocene such as the product sold by BASF SE under the name Irgacure ^® 784,
• Oxime esters such as the product sold by BASF SE under the name Irgacure ^® OXE01 and OXE02,
• alpha-aminoalkylphenones such as 2-methyl-1-[4(methylthio)phenyl-2-morpholinopropan-1-one, 2-(4-methylbenzyl)-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone or 2 -Benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone.

Preferred photoinitiators are primarily selected from the groups of alpha-hydroxyalkylphenones, alpha-dialkoxyacetophenones, phenylglyoxalic acid esters, benzophenones, benzoins and acylphosphine oxides.

The liquid, radiation-curable composition preferably contains at least one photoinitiator which has an absorption band with a maximum λ _max in the range from 230 to 340 nm.

The non-aqueous, liquid, radiation-curable composition used to produce the lacquer layer preferably contains at least two different photoinitiators in which the maxima of the absorption bands differ, preferably by at least 40 nm and in particular by at least 60 nm.

In particular, such a non-aqueous, liquid, radiation-curable composition contains a mixture of at least two different photoinitiators, with at least one photoinitiator (hereinafter photoinitiator I) having an absorption band with a maximum λ _max in the range from 340 to 420 nm and especially in the range from 360 to 420 nm and wherein at least one further photoinitiator (hereinafter photoinitiator II) has an absorption band with a maximum λ _max in the range from 220 to 340 and especially in the range from 230 to 320 nm. The weight ratio of the total amount of photoinitiators I to the total amount of photoinitiators II is preferably in the range from 2:1 to 1:20.

Preferred photoinitiators which have an absorption band with a maximum λ _max in the range from 220 to 340 and especially in the range from 230 to 320 nm are the aforementioned alpha-hydroxyalkylphenones, alpha-dialkoxyacetophenones, phenylglyoxalic acid esters, benzophenones and benzoins.

Preferred photoinitiators which have an absorption band with a maximum λ _max in the range from 340 to 420 nm and especially in the range from 360 to 420 nm are the aforementioned acylphosphine oxides.

In preferred embodiments, the photoinitiators comprise at least one alpha-hydroxyalkylphenone or alpha-dialkoxyacetophenone and at least one acylphosphine oxide and optionally a phenylglyoxylic acid ester and optionally a benzophenone. The weight ratio of acylphosphine oxide to alpha-hydroxyalkylphenone or alpha-dialkoxyacetophenone is preferably in the range from 2:1 to 1:20.

The total amount of photoinitiators is typically in the range from 0.5 to 10% by weight, in particular 1 to 5% by weight, based on the total weight of the non-aqueous liquid radiation-curable composition.

The nonaqueous, liquid, radiation-curable compositions according to the invention can also be formulated without an initiator, particularly when the subsequent curing takes place by means of electron beams.

Furthermore, the non-aqueous, liquid, radiation-curable compositions can contain one or more fillers, i. H. solid particulate components which are insoluble in the oligomers and the monomers. These include, above all, aluminum oxides, for example in the form of corundum, and silicon dioxide, such as pyrogenic silica and synthetic, amorphous silica, e.g. B. Precipitated silica. The mean particle sizes of the fillers (weight average) can vary over a wide range and are typically in the range from 1 nm to 100 μm, in particular in the range from 10 nm to 50 μm, depending on the type of filler. The total amount of filler will generally not exceed 40%, especially 30% by weight based on the total weight of the composition and, if included, will typically range from 1 to 39.5% by weight and especially in the range of 2 to 29% by weight.

The non-aqueous, liquid, radiation-curable compositions preferably contain one or more abrasives. Abrasives are fillers that give the paint layer increased surface hardness and improved abrasion resistance. These include above all corundum, quartz powder, glass powder, e.g. B. glass flakes and nanoscale silica.

In addition, the non-aqueous, liquid, radiation-curable compositions can contain one or more other additives, for example flow control agents, e.g. B. siloxane-containing polymers such as polyether siloxane copolymers, and UV stabilizers, z. B. sterically hindered amines (so-called HALS stabilizers).

Typical compositions of the non-aqueous, liquid, radiation-curable compositions which are used to produce the lacquer layer are given in Tables A1, A2 and A3 below. Table A1: raw material Amount [% by weight] ¹⁾ Urethane acrylate, functionality about 2.0 to 6.0 15 - 30 Polyester acrylate, functionality 3.0 to 3.5 5 - 15 Trimethylolpropane formal monoacrylate 5 - 15 trimethylolpropane triacrylate 10 - 20 dipropylene glycol diacrylate 10 - 20 Aliphatic urethane acrylate, functionality 1.5 to 3.5 3 - 15 aluminum oxide (corundum) 20 - 30 Fumed silica 0.1 - 5 phenyl glyoxylate 0.5 - 3 acylphosphine oxide 0.2 - 1 alpha-hydroxyalkylphenone 0.5 - 3 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Urethane acrylate, functionality about 2.0 to 6.0 20 - 35 Aliphatic urethane acrylate, functionality 1.5 to 2.0 12 - 25 Trimethylolpropane formal monoacrylate 5 - 15 phenoxyethyl acrylate 10 - 20 dipropylene glycol diacrylate 10 - 20 Synthetic silica 5 - 15 Fumed silica 0.1 - 5 leveling agent (e.g. polyethersiloxane) 0.2 - 5 phenyl glyoxylate 0.5 - 3 acylphosphine oxide 0.1 - 0.5 alpha-hydroxyalkylphenone 0.5 - 3 benzophenone 0.5 - 3 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Mixture of two or three polyester acrylates, average functionality 2.0 to 4.0 40 - 65 Trimethylolpropane formal monoacrylate 5 - 20 Acrylate of an ethoxylated phenol 5 - 20 dipropylene glycol diacrylate 5 - 20 Fumed silica 1 - 10 leveling agent (e.g. polyethersiloxane) 0.2 - 5 phenyl glyoxylate 0.5 - 3 acylphosphine oxide 0.1 - 1 alpha-hydroxyalkylphenone 0.5 - 3 benzophenone 0.5 - 3 1) based on the total weight of the composition

The thermal transfer foils according to the invention can have one or more lacquer layers arranged one on top of the other, which according to the invention are based on the above-described non-aqueous, liquid, radiation-curable compositions.

The total layer thickness of the paint layer, i. H. in the case of several paint layers, the sum of all layer thicknesses is typically in the range from 10 to 120 μm, in particular in the range from 30 to 80 μm. In the case of one layer, the layer thickness of the lacquer layer is therefore preferably in the range from 10 to 120 μm, in particular in the range from 30 to 80 μm. In the case of several layers, the individual layer thicknesses are typically in the range from 10 to 100 μm, in particular in the range from 20 to 70 μm.

In a first embodiment of the invention, the thermal transfer film according to the invention comprises exactly one lacquer layer arranged on the carrier film.

In a further embodiment, the thermal transfer film according to the invention comprises a lacquer layer arranged on the carrier film and one or more, e.g. B. one or two further coating layers based on the non-aqueous, liquid, radiation-curable compositions described above. The lacquer layers can be arranged directly one on top of the other. A decorative layer can also be provided between two lacquer layers in order to give the object coated with the thermal transfer film a colored design.

Decorative layers typically have layer thicknesses in the range from 0.5 to 5 μm, in particular in the range from 0.5 to 2.5 μm and especially in the range from 1 to 1.5 μm.

Furthermore, the thermal transfer films according to the invention have at least one polymeric adhesive layer, in particular precisely one adhesive layer. The adhesive layer is either arranged directly on the lacquer layer or, in the case of several lacquer layers, directly on the uppermost lacquer layer, or a decorative layer can also be provided between the lacquer layer and the adhesive layer.

According to the invention, the adhesive layer is heat-sealable, ie it is not tacky at room temperature and develops its adhesive effect only when heated. The adhesive layer contains at least one component that crosslinks when exposed to UV light. This component is an organic oligomer or polymer that has ethylenically unsaturated double bonds. The adhesive layer is based on at least two aqueous polymer dispersions, at least one polymer dispersion containing a UV-curable polymer in dispersed form and at least one further polymer dispersion containing a self-crosslinking polymer in dispersed form.
Preferably, the heat-sealable adhesive sheet of the present invention comprises at least one polymer as a main component. The polymer itself can be radiation-curable or it can be blended with one or more radiation-curable oligomers or polymers which have ethylenically unsaturated double bonds.
The polymers, which form the main component of the heat-sealable adhesive layer, are crosslinkable, ie they crosslink when heated or when irradiated with UV light to form covalent bonds between the polymer chains.
In particular, it has proven to be advantageous that the adhesive layer comprises both oligomeric and/or polymeric components that can be crosslinked by heating and components that can be crosslinked by exposure to UV radiation. This is achieved in that the adhesive layer comprises both polymers, which crosslink when heated, and oligomers or polymers, which are crosslinked through the action of UV radiation. The adhesive layer can also contain so-called dual-cure polymers, ie polymers which crosslink both when exposed to high-energy radiation and when heated.
According to the invention, the adhesive layer contains at least one water-insoluble polymer from an aqueous polymer dispersion, which is usually used for the production of adhesive layers, and in particular from pure acrylate polymers, Styrene acrylate polymers, polyurethanes, in particular polyester urethanes and polyether urethanes, and which is self-crosslinking, and at least one radiation-curing oligomer or polymer from an aqueous polymer dispersion.

Physically drying polymers are those polymers which, on drying, form a solid polymer film in which the polymer chains are not crosslinked. Self-crosslinking polymers are those polymers which, on drying, form a solid polymer film in which the polymer chains are crosslinked. Self-crosslinking polymers have reactive functional groups, for example hydroxyl groups, carboxyl groups, isocyanate groups, blocked isocyanate groups, ketocarbonyl groups or epoxide groups, which can react with one another or with the reactive groups of a crosslinking agent to form covalent bonds.

In a particularly preferred embodiment, the adhesive layer contains at least one water-insoluble polymer selected from polyurethanes, in particular polyester urethanes and polyether urethanes, and which is physically drying or self-crosslinking, and at least one radiation-curing oligomer or polymer.

In a likewise particularly preferred embodiment, the adhesive layer contains at least one water-insoluble polymer selected from self-crosslinking pure acrylate polymers and self-crosslinking styrene acrylate polymers, and at least one radiation-curing oligomer or polymer.

In a likewise particularly preferred embodiment, the adhesive layer contains at least one water-insoluble polymer selected from self-crosslinking pure acrylate polymers and self-crosslinking styrene acrylate polymers and at least one water-insoluble polymer selected from polyurethanes, in particular polyester urethanes and polyether urethanes, and which is physically drying or self-crosslinking is, and at least one radiation-curing oligomer or polymer.

The radiation-curable oligomers and polymers of the adhesive layer are basically those oligomers and polymers which have ethylenically unsaturated double bonds. These double bonds are preferably at least 90% or 100%, based on the total amount of the ethylenically unsaturated double bonds, in the form of acrylic or methacrylic groups and especially in the form of acrylic groups. The acrylic and methacrylic groups may be in the form of (meth)acrylamide or (meth)acrylate groups, with the latter being preferred. In particular, the radiation-curable components of the adhesive layer contain acrylate groups to an extent of at least 90% or 100%, based on the total amount of the ethylenically unsaturated double bonds present in the adhesive layer.

The radiation-curable oligomers and polymers of the adhesive layer preferably have an average functionality in the range from 2 to 20, in particular in the range from 2 to 10, i. H. the number of ethylenically unsaturated double bonds per molecule is on average in the range from 2 to 20 and in particular in the range from 2 to 10.

Mixtures of different oligomers or polymers with different functionality are also suitable, the average functionality preferably being in the range from 2 to 20, in particular in the range from 2 to 10.
In particular, the radiation-curable oligomers and polymers of the adhesive layer are selected from polyether (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, for example reaction products of polyisocyanates with hydroxyl-functionalized acrylic or methacrylic compounds, and unsaturated ones polyester resins.

Specifically, the radiation-curable oligomers and polymers of the adhesive layer are selected from polyether (meth)acrylates, epoxy (meth)acrylates and urethane (meth)acrylates.
Suitable polyurethane acrylates are primarily polymers containing urethane groups which have an average of 2 to 10, in particular 2 to 8.5, acrylate or methacrylate groups, in particular polyether urethane arylates, and which are preferably obtainable by reacting polyether urethanes containing isocyanate groups with hydroxyalkyl acrylates or hydroxyalkyl methacrylates . Examples of this are the ^Laromer® types LR 8949, LR 8983 and LR 9005 from BASF SE.
Furthermore, it has proven to be advantageous if the polymers, which preferably form the main component of the heat-sealable adhesive layer, have a glass transition temperature Tg in the uncrosslinked state, determined by means of differential scanning calorimetry (DSC) according to ASTM D3418 in the range from -60 to 90 ° C, in particular 0 to 90°C, and/or they are partially crystalline polymers with a melting point in the range from -60 to 90°C, in particular 0 to 90°C, determined by DSC. If the adhesive composition contains several polymers, these can also have different glass transition temperatures in the uncrosslinked state. It is then preferred that at least part, in particular at least 30% by weight, of these polymers, based on the total amount of the polymer components of the adhesive composition, in the uncrosslinked state have a glass transition temperature Tg in the range from 0 to 90° C., in particular in the range from 20 to 90 °C. Adhesive compositions for producing heat-sealable polymer layers are familiar to the person skilled in the art and can be purchased commercially or produced by mixing commercially available adhesive raw materials according to known guide recipes.

According to the invention, the adhesive layer (4) is based on at least two aqueous polymer dispersions, ie water-based adhesives are used to produce the adhesive layer, ie adhesives which contain the polymers and optionally oligomers in the form of aqueous polymer dispersions. Preference is given to liquid, water-based adhesive compositions which contain no more than 10% by weight of volatile, organic, non-polymerizable components such as organic solvents.
Suitable polymer dispersions are self-crosslinking aqueous polymer dispersions, ie aqueous polymer dispersions which contain a reactive dispersed polymer and optionally a crosslinking agent which reacts with the reactive groups of the reactive polymer on drying and/or heating to form a bond. Particularly suitable are self-crosslinking aqueous pure acrylate dispersions, self-crosslinking aqueous styrene acrylate dispersions and self-crosslinking aqueous polyurethane dispersions, in particular aqueous polyether urethane dispersions and polyester urethane dispersions.

Pure acrylate dispersions are understood as meaning aqueous polymer dispersions based on alkyl acrylates and alkyl methacrylates. Styrene acrylates are understood as meaning aqueous polymer dispersions based on styrene, alkyl acrylates and optionally alkyl methacrylates. Polyurethane dispersions are understood as meaning aqueous dispersions of polyurethanes, in particular polyether urethanes and polyester urethanes.

In the self-crosslinking aqueous polymer dispersions, the polymers have reactive functional groups, for example hydroxyl groups, carboxyl groups, isocyanate groups, blocked isocyanate groups, ketocarbonyl groups or epoxide groups, which can react with the reactive groups of the crosslinking agent to form covalent bonds. Suitable crosslinking agents are compounds with at least two reactive groups, for example hydrazide groups, amino groups, hydroxyl groups, epoxide groups, isocyanate groups. Examples of self-crosslinking aqueous polymer dispersions are the products available under the trade names ^Luhydran® A 849, ^Acronal® 849 S, ^Joncryl® 8330, ^Joncryl® 8383 from BASF SE and ^Alberdingk® AC 2742 from Alberdingk Boley GmbH.

Suitable aqueous polymer dispersions are UV-crosslinkable polymer dispersions, ie polymer dispersions which contain a dispersed polymer which has polymerizable ethylenically unsaturated double bonds, preferably in the form of the aforementioned acrylic groups, methacrylic groups, allyl groups, fumaric acid groups, maleic acid groups and/or maleic anhydride groups, in particular in the form of acrylic - or methacryl groups are present, it being possible for the ethylenically unsaturated double bonds to be bonded to the basic structure via a linker or to be part of the basic structure. Examples of suitable UV-crosslinkable aqueous polymer dispersions are aqueous dispersions of polyester acrylates, urethane acrylates and epoxy acrylates, such as those sold by BASF under the trade names Laromer® ^PE22WN , PE55WN, LR8949, LR8983, LR9005, UA9060, UA9095 and UA9064.

According to the invention, the aqueous adhesive composition contains, in addition to the polymer of a self-crosslinking polymer dispersion, at least one UV-curable component which is generally selected from the aforementioned polymers and oligomers which have ethylenically unsaturated double bonds and which is also present in dispersed form, i. H. in the form of an aqueous polymer dispersion.

The radiation-curable oligomers and polymers of the aqueous adhesive composition are, in particular, oligomers and polymers whose double bonds are at least 90% or 100%, based on the total amount of ethylenically unsaturated double bonds, in the form of acrylic or methacrylic groups and especially in the form of acrylic groups present. The acrylic and methacrylic groups may be in the form of (meth)acrylamide or (meth)acrylate groups, with the latter being preferred.

The radiation-curable oligomers and polymers of the aqueous adhesive composition preferably have on average a functionality in the range from 2 to 20, in particular in the range from 2 to 10, ie the number of ethylenically unsaturated double bonds per molecule is on average in the range from 2 to 20 and in particular in the range from 2 to 10. Mixtures of different are also suitable Oligomers or polymers with different functionality, the average functionality preferably being in the range from 2 to 20, in particular in the range from 2 to 10.

In particular, the radiation-curable oligomers and polymers of the aqueous adhesive composition are selected from polyether (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, and unsaturated polyester resins.

Specifically, the radiation-curable oligomers and polymers of the aqueous adhesive composition are selected from polyether (meth)acrylates, epoxy (meth)acrylates and polyurethane (meth)acrylates.

Suitable polyurethane acrylates are, in particular, polymers containing urethane groups which have on average 2 to 10, in particular 2 to 8.5, acrylate or methacrylate groups and which are preferably obtainable by reacting polyurethanes containing isocyanate groups with hydroxyalkyl acrylates or hydroxyalkyl methacrylates. Examples of these are the ^Laromer® types LR 8949, LR 8983 and LR9005 from BASF SE.

According to the invention, these are mixtures of at least two different aqueous polymer dispersions, namely mixtures of at least one aqueous UV-crosslinkable polymer dispersion, e.g. B. an aqueous urethane acrylate dispersion and / or an aqueous epoxy acrylate dispersion, and at least one self-crosslinking aqueous polymer dispersion, z. B. a self-crosslinking aqueous pure acrylate, styrene acrylate or polyurethane dispersion.

The adhesive compositions used to produce the polymeric adhesive layer can contain the additives customary for this purpose, for example waxes, adhesive resins, defoamers, flow control agents, surfactants, agents for adjusting the pH value, one or more of the aforementioned fillers and UV stabilizers, e.g. B. sterically hindered amines (so-called HALS stabilizers).

The adhesive composition used to prepare the polymeric adhesive layer typically also contains at least one photoinitiator, typically selected from the aforementioned alpha-hydroxyalkylphenones, alpha-dialkoxyacetophenones, phenylglyoxylic esters, benzophenones, benzil derivatives, acylphosphine oxides, oxime esters, alpha-aminoalkylphenones and benzoins. Preferred photoinitiators are primarily selected from the groups of alpha-hydroxyalkylphenones, alpha-dialkoxyacetophenones, phenylglyoxalic acid esters, benzophenones, benzoins and acylphosphine oxides.

The adhesive composition used to produce the polymeric adhesive layer preferably contains at least one photoinitiator which has an absorption band with a maximum λ _max in the range from 230 to 340 nm. In particular, it contains at least two different photoinitiators in which the maxima of the absorption bands differ, preferably by at least 40 nm and in particular at least 60 nm. In particularly preferred embodiments, the photoinitiators include at least one alpha-hydroxyalkylphenone or alpha-dialkoxyacetophenone and at least one acylphosphine oxide as well optionally a phenylglyoxylic acid ester and optionally a benzophenone. The weight ratio of acylphosphine oxide to alpha-hydroxyalkylphenone or alpha-dialkoxyacetophenone is preferably in the range from 2:1 to 1:20. The total amount of photoinitiators is typically in the range from 0.5 to 10% by weight, in particular 1 to 5% by weight % based on the total weight of the adhesive composition used to make the polymeric adhesive layer.

Examples of typical adhesive compositions include the following compositions, all parts being percentages by weight based on the total weight of the composition: Adhesive composition 1 (UV curable, unpigmented) 30 -70 parts a self-crosslinking aqueous acrylate dispersion (50% by weight) 10-50 parts a radiation-curable polyurethane acrylate dispersion (40-50% by weight), 5-10 Parts of a hydrophobic fumed silica 5-10 Parts of a non-ionic wax dispersion 1.5-3 Parts of a blend of an alpha-hydroxyalkylphenone and benzophenone 0.5-1 Parts of an acylphosphine oxide and optionally the following components 0-20 share water 0.8-1.5 parts a mineral-based defoamer 0.4-1.2 parts a polyethersiloxane copolymer 0.5-1.0 parts a leveling agent containing fluorosurfactant 2-4 parts Butyl glycol as a film-forming agent 0.3-0.5 Parts of a polyurethane thickener 25-45 parts a self-crosslinking aqueous acrylate dispersion (50% by weight) 10-20 parts a radiation-curable aqueous polyetherurethane acrylate dispersion (40-50% by weight) 3-10 parts Epoxy acrylate, water-dilutable 1-5 parts a fumed silica or a combination of a fumed silica and an amorphous synthetic silicate 1-6 parts a non-ionic wax dispersion 2-10 parts a wax, e.g. B. carnauba wax, polyethylene wax, a combination of carnauba wax and polyethylene wax or a combination of several polyethylene waxes 1-3 parts a blend of an alpha-hydroxyalkylphenone and benzophenone 0.5-1 parts an acylphosphine oxide and optionally the following ingredients 0.2-1.0 parts a polyethersiloxane copolymer 1-10 parts Hydroxystyrene Acrylate Copolymer 0.1-5 parts plasticizers, e.g. B. triethyl citrate 0.5-5 parts water 0.5-5 parts Butyl glycol as a film-forming agent 0.01-1 parts base, e.g. B. an organic amine 25-45 parts a self-crosslinking aqueous acrylate dispersion (50% by weight) 5-20 parts a radiation-curable aqueous polyetherurethane acrylate dispersion (40-50% by weight) 3-10 parts Epoxy acrylate, water-dilutable 5-25 parts color pigment, e.g. As titanium dioxide or colored pigment 1-8 parts a fumed silica or an amorphous synthetic silicate or a combination of a fumed silica and an amorphous synthetic silicate 1-6 parts a non-ionic wax dispersion 2-10 parts a wax, e.g. B. carnauba wax, polyethylene wax, a combination of carnauba wax and polyethylene wax or a combination of several polyethylene waxes 1-10 parts Hydroxystyrene Acrylate Copolymer 1-3 parts a blend of an alpha-hydroxyalkylphenone and benzophenone 0.5-1 parts an acylphosphine oxide and optionally the following ingredients 0.1-5 parts plasticizers, e.g. B. triethyl citrate 0.2-1.0 parts a polyethersiloxane copolymer 0.2-1.0 parts a defoamer, e.g. B. a silicone defoamer or a siloxane-free defoamer; 0.3-0.5 parts a leveling agent, e.g. B. a fluorosurfactant-containing leveling agent 0.5-5 parts water 0.5-5 parts Butyl glycol as a film-forming agent 0.01-1 parts base, e.g. B. an organic amine 15 -60 parts a polyester urethane dispersion (40% by weight) 15 -60 parts a self-crosslinking aqueous acrylate dispersion (50% by weight) 10-50 parts a radiation-curable aqueous polyetherurethane acrylate dispersion (40-50% by weight) 1.5-3 parts a blend of an alpha-hydroxyalkylphenone and benzophenone 0.5-1 parts an acylphosphine oxide and optionally the following ingredients 0-20 parts water 0.8-1.5 parts a polysiloxane defoamer 0.4-1.2 parts a polyethersiloxane copolymer 0.5-1.0 parts a leveling agent containing fluorosurfactant 0.01-0.5 Parts of a polyurethane thickener

Furthermore, it may be desirable for the adhesive layer(s) and/or the lacquer layer(s) to be colored. For this purpose, the lacquer layer(s) and/or the adhesive layer(s) can contain one or more coloring components such as organic and/or inorganic pigments or dyes. Examples of these pigments are titanium dioxide as a white pigment, iron oxide pigments such as iron oxide yellow, iron oxide red, iron oxide black, black pigments such as carbon black, phthalocyanine pigments such as heliogen blue or heliogen green, bismuth pigments such as bismuth vanadate yellow and diketopyrrolopyrrole red. Metal pigments such as iron pigments, pearlescent pigments and aluminum pigments can also be included for metallization effects. Preferred pigments typically have particle sizes in the range from 0.1 to 100 μm, in particular in the range from 1 to 50 μm.

Adhesive layers typically have layer thicknesses in the range from 5 to 25 μm.

The thermal transfer films according to the invention naturally have at least one carrier film on which the at least one lacquer layer is arranged. The carrier foils are usually plastic foils made from thermoplastic, flexible polymers. In particular, these are polyester films, polyamide films, polypropylene films, films made from polyvinyl alcohol or polyesteramide films. So-called coextrudate films are also suitable, i. H. foils consisting of several layers, whereby the plastic material in the individual layers can be different. Preferably, the plastic material forming the carrier film is predominantly amorphous. Waxed or siliconized papers are also suitable. The carrier film (2) preferably has a thickness in the range from 3 to 200 μm, in particular from 10 to 100 μm and especially from 20 to 50 μm. Thin carrier films with film thicknesses in the range from 3 to 30 μm are also suitable.

The surface structure of the carrier film on which the layer of lacquer is arranged naturally determines the degree of gloss of the layer of lacquer which is obtained in the coating method according to the invention. Smooth surfaces lead to glossy or high-gloss surfaces, whereas rough surfaces can produce matt effects. It is possible to create coarser structures in the paint surface by heavily structuring the surface.

The surface of the carrier film on which the lacquer layer is arranged can have a customary release layer, which facilitates the detachment of the lacquer layer from the carrier film in the coating method according to the invention.

The thermal transfer foils can be produced in analogy to conventional foil coating technologies, as also described in the prior art cited at the outset, with the difference that no heat drying step is carried out in the production of the lacquer layer, but rather by applying the non-aqueous, radiation-curable, liquid Composition on the carrier film obtained liquid paint layer is at least partially cured by treatment with high-energy radiation such as electron beams or UV radiation.

The non-aqueous, radiation-curable, liquid composition can be applied to the carrier film in step i) of the process according to the invention in a manner known per se, for example by knife-coating, rolling, pouring or spraying. In this way, a coating of the carrier film with the radiation-curable composition is obtained, which can then be cured by treatment with high-energy radiation. The application quantity is usually selected in such a way that a layer thickness in the ranges mentioned above results. As a rule, the amount applied is in the range from 10 to 120 g/m ² , in particular in the range from 30 to 80 g/m ² and, in the case of several layers, preferably in the range from 10 to 100 g/m ² and in particular 20 to 70 g/m 2 ^m2 .

In step ii) of the method according to the invention, the coating obtained in step i) is then high-energy radiation at least partially cured. Optionally, before complete curing, a decorative layer can be applied to the not yet cured or partially cured coating. If necessary, the adhesive layer can also be applied before curing. In step ii) of the method according to the invention, the coating obtained in step i) is preferably only partially cured. Preferably, however, the layer obtained in step i) is at least partially cured before the application of the heat-sealable, polymeric adhesive layer and before the optional application of the decorative layer.

For curing in step ii), the coating obtained in step i) is irradiated with high-energy radiation. The irradiation can take place through the carrier film or by direct irradiation of the coating. Direct irradiation is preferred.

The irradiation can take place by means of electron beams or with UV light, for example with UV lamps or light-emitting diodes emitting UV radiation. UV radiation is preferably used for curing in step ii). In particular, UV radiation in the wavelength range from 200 to 400 nm is used. Medium-pressure or high-pressure mercury lamps are preferably used for this purpose. In many cases, high-pressure mercury lamps doped with gallium or iron are used.

The irradiation in step ii) is preferably carried out in such a way that only partial polymerization of the ethylenically unsaturated double bonds present in the nonaqueous, radiation-curable, liquid composition takes place. The radiation density required for this can be determined by a person skilled in the art through routine experiments.

Typically, the irradiation in step ii) takes place at a radiation density in the range from 80 to 2000 J/m ² , in particular in the range from 110 to 400 J/m ² .

The curing in step ii) can be carried out under an air atmosphere or under a low-oxygen atmosphere with residual oxygen concentrations below 2000 ppm, e.g. B. at residual oxygen concentrations in the range of 50 to 1000 ppm. Curing preferably takes place in air.

If the thermal transfer film according to the invention has several layers of lacquer, the individual layers of lacquer can be applied, for example, in a liquid-liquid application, i. H. the second coat of paint and any further coats of paint are applied to the still liquid first coating before curing. However, the first lacquer layer is preferably at least partially cured by high-energy radiation before the further lacquer layer(s) are applied.

If necessary, a decorative layer is applied to the layer of paint before the application of the adhesive layer or, in the case of several layers of paint, also to the first layer of paint. This decorative layer can be applied in a manner known per se using suitable printing methods, for example flat, gravure, inkjet or digital printing. The lacquer layer is preferably partially cured before the decorative layer is applied, the partial curing preferably being carried out only to the extent that the decorative layer can just still be applied. The printing inks used to produce the decorative layer can be conventional printing inks or UV-curing printing inks.

The heat-sealable adhesive layer can be applied in step iv) of the method according to the invention in a manner known per se. For this purpose, a liquid adhesive composition, in particular an aqueous adhesive composition, is generally applied to the lacquer layer or the decorative layer in a conventional manner, for example by doctor blade, roller, pouring or spraying. The adhesive layer is then dried, for example by heat. The amount of liquid adhesive composition applied is generally chosen so that, after drying, a layer thickness in the above-mentioned ranges results. The amount applied is generally in the range from 5 to 50 g of solids per m ² , in particular in the range from 5 to 15 g of solids per m ² .

For example, the following film structures 1 to 12 can be produced with the method according to the invention by using the steps specified there. Here, the film structures 7 to 12 correspond to the film structures 1 to 6 with the difference that a pigment-containing adhesive composition is used.

Foil structure 1:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable, non-abrasive, colorless composition;
3. 3. Partial hardening of the paint layer using UV radiation;
4. 4. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components;
5. 5. Air heat drying.

Foil structure 2:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable, non-abrasive composition;
3. 3. Partial hardening of the paint layer using UV radiation;
4. 4. Application of a decorative layer by gravure printing or digital printing using a UV-curable ink;
5. 5. Drying of the decorative layer by means of UV radiation;
6. 6. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components to the decorative layer;
7. 7. Air heat drying.

Foil structure 3:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable, non-abrasive composition containing colored pigments;
3. 3. Partial hardening of the colored lacquer layer using UV radiation;
4. 4. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components on the paint layer;
5. 5. Air heat drying.

Foil structure 4:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable composition containing corundum;
3. 3. Drying of the colored lacquer layer by means of UV radiation;
4. 4. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components on the paint layer;
5. 5. Air heat drying.

Foil structure 5:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable composition containing corundum;
3. 3. Partial hardening of the paint layer using UV radiation;
4. 4. Application of a decorative layer by gravure printing or digital printing using a UV-curable ink;
5. 5. Drying of the decorative layer by means of UV radiation;
6. 6. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components to the decorative layer;
7. 7. Air heat drying.

Foil structure 6:

1. 1. Providing a carrier film;
2. 2. Coating of the carrier film with a liquid, radiation-curable, abrasive-containing composition containing colored pigments;
3. 3. Partial hardening of the colored lacquer layer using UV radiation;
4. 4. Application of a claimed, water-based, pigment-free adhesive composition with radiation-curable components on the paint layer;
5. 5. Air heat drying.

The thermal transfer films thus obtained can then be finished in the usual way, e.g. B. be wound into rolls.

The thermal transfer films according to the invention are particularly suitable for dry coating of the surfaces of objects. As already described at the beginning, the paint layer or layers of paint are transferred to the surface of the object to be coated, hereinafter also referred to as the substrate, by means of heat and/or pressure, with the adhesive layer providing a good adhesive bond between the or the paint layers and the substrate causes. The use of the thermal transfer foils according to the invention is not limited to certain substrates, but they can be used in a wide variety of ways, both with hard and with elastic substrates.

The substrates can be, for example, objects made of plastic, for example ABS, polycarbonate, melamine, polyester, including glass fiber reinforced polyester, hard PVC, soft PVC, rubber, wood including exotic natural wood, wood-based materials, e.g. As veneer, MDF, HDF, chipboard or multiplex boards, mineral fibers, z. As mineral fiber boards, paper, textiles including artificial leather, metal or plastic-coated materials act. The thermal transfer films according to the invention are preferably suitable for smooth, preferably flat or slightly curved surfaces. In principle, however, more complex structures can also be coated in this way. The substrates to be coated can be undecorated or already have decorative surfaces. Exotic natural woods, which often cause problems in wet painting, can be coated particularly advantageously using the thermal transfer films according to the invention, since the ingredients bleed out or adhesion problems are caused. The objects coated using the thermal transfer films according to the invention, e.g. B. wood fiber boards, MDF boards or natural wood boards, which have been primed using the thermal transfer films according to the invention, can easily be further coated with a conventional UV varnish, with no intermediate sanding being required. Alternatively, an object primed in this way can also be dry-coated with a thermal transfer film according to the invention.

The thermal transfer films according to the invention allow objects to be coated with almost no waste. In industrial production, a change from colorless to colored, from matt to glossy, can take place very quickly without a cleaning step being necessary between this change. Drying times are eliminated and work can continue immediately after coating, e.g. B. applied a conventional coat of paint or the coated object are packaged. The carrier film can be detached or initially remain on the coated surface as a protective film. Compared to conventional coating processes, the use of the thermal transfer foils according to the invention allows dust-free coating. In addition, the space requirement and personnel costs are much lower compared to conventional painting processes.

In comparison to the thermal transfer foils known from the prior art, the thermal transfer foils according to the invention provide surfaces with a particularly high quality, in particular high scratch and abrasion resistance. For example, surfaces of quality classes AC3 to AC4 (DIN EN 13329) can be achieved. The surfaces obtained using the thermal transfer films according to the invention regularly show values above 20 N when tested with the Hamberger planer. The surfaces obtained in this way regularly meet the requirements of the highest stress group of the furniture standard DIN 68861.

The use of the thermal transfer foils according to the invention for coating surfaces of objects is typically carried out in a process which comprises the aforementioned steps a) to d), which are described in more detail below and which are carried out analogously to in EP 2078618 A2 described procedure can be carried out. On the relevant content of EP 2078618 A2 is hereby referred to.

In this case, the thermal transfer film according to the invention is first applied to the surface of the substrate to be coated and then heat-sealed. Heat sealing is typically carried out using pressure in suitable presses, the temperature of the press typically being in the range 100 to 250°C, preferably in the range 160 to 220°C. Roller presses are preferred, since only brief contact is required in this way, so that the object temperature does not exceed a value of 70° C., in particular 60° C. Heat-sensitive substrates can also be coated in this way.

The substrate coated in this way is then exposed to high-energy radiation, i. H. with UV or electron beams, whereupon the lacquer layer hardens completely. The irradiation can be carried out before removing the carrier film or afterwards. For a number of applications, it is advantageous to carry out the irradiation before removing the carrier film, since the carrier film then remains on the coated substrate as a protective film.

The irradiation can be done by means of electron beams, e.g. B. using gallium emitters or UV light, for example with UV lamps or UV radiation emitting light-emitting diodes. UV radiation is preferably used for curing in step ii). In particular, UV radiation in the wavelength range from 200 to 400 nm is used. Medium-pressure or high-pressure mercury lamps are preferably used for this purpose. In many cases, high-pressure mercury lamps doped with gallium or iron are used.

Typically, the irradiation in step ii) takes place at a radiation density in the range from 40 to 2000 J/m ² , in particular in the range from 100 to 400 J/m ² .

A system for carrying out the method according to the invention comprises at least one thermal transfer device which is usually used and which preferably has a cutting device and/or a winding device for the carrier film. Depending on the intended use of the finished painted object, the plant may have a first thermal transfer device with which the object is primed and a second thermal transfer device with which the object is top-coated.

A conventional thermal transfer device can be constructed as follows: the thermal transfer foil wound up as a roll is guided from a foil unwinding device to a heated roller press which has at least one driven, heated, optionally rubberized roller, which is optionally height-adjustable. The roller press generally has a counter-pressure roller which is opposite the heated roller and which can be rubberized. This creates the necessary pressure, whereby the layer of paint is transferred by means of the adhesive layer to the surface of an object that is guided between the two rollers. The counter-pressure roller can be designed in such a way that it separates the carrier film from the lacquer layer. The separated carrier film can be removed with a cutting device or fed to a film winding device. Instead of a roller press, a platen press can also be used, which is opened after a predetermined time.

The coated object is then passed with the coated side past a source of high-energy radiation, for example an electron beam or a UV lamp, whereby the coated side of the object is exposed to high-energy radiation and final curing is achieved. The object coated in this way is then fed to a collecting device, for example a stacking device. Before or after the irradiation, the carrier film can be removed with a cutting device or fed to a film winding device.

After detaching the carrier film, the object coated in the thermal transfer device can also be fed to a further thermal transfer device before or after curing by means of high-energy radiation, in which another layer of lacquer is applied to the coated surface of the object using a further thermal transfer film according to the invention. Curing with high-energy radiation preferably takes place after the application of the further lacquer layer, as described above.

A first embodiment of a device for continuously carrying out the method according to the invention with solid substrates has a loading conveyor belt, an unwinding station for the thermal transfer film wound up as a roll, a thermal transfer device with a roller press, as described above, a winding device for the carrier film, a drying tunnel with UV emitter , an outfeed conveyor and a stacking device.

The substrates to be coated, preferably plates, are placed on the conveyor belt and fed through the thermal transfer device at the desired feed rate. Here, the lacquer layer is transferred to the substrate and the carrier film is separated and picked up by the winding device. The paint layer is then cured in the drying tunnel. The winding station can also be arranged after the drying tunnel, so that the carrier film initially remains on the substrate and acts there as a protective film.

A second embodiment of a device for continuously carrying out the method according to the invention with elastic substrates has an unwinding station for the substrate, an unwinding station for the thermal transfer film wound up as a roll, a thermal transfer device with a roller press, as described above, a drying tunnel with a UV emitter and a winding device for the coated substrate.

The substrate to be coated is fed through the thermal transfer device together with the thermal transfer film at the desired feed rate. Here, the thermal transfer film is connected to the substrate. The substrate coated in this way is then fed through the drying tunnel, causing the layer of paint to harden and is picked up by the winding station. After cutting, the carrier film can be removed.

A third embodiment of a device for continuously carrying out the method according to the invention with solid substrates has a conveyor belt, an unwinding station for the thermal transfer foil wound up as a roll, a thermal transfer device with a heated platen press and, if necessary, a winding device for the carrier foil or a cutting device.

The substrates to be coated, preferably plates, are placed on the conveyor belt and fed into the platen press together with the thermal transfer foil. The press is closed and the desired pressure is applied. In this case, the lacquer layer is transferred to the substrate. After opening the press, the substrate is moved out of the press and passed through the drying tunnel, causing the paint layer to harden. In this case, the carrier film can remain on the substrate and serve as a protective film. In this case, the carrier foil can be cut with a cutting device before or after the drying tunnel. Alternatively, it is possible to place the film as a whole in front of the UV channel cut off and fed to the winding device.

A further embodiment of a device for discontinuously carrying out the method according to the invention with solid substrates has a conveyor belt, an unwinding station for the thermal transfer film wound up as a roll, a cutting device, thermal transfer device with heated platen press and a drying tunnel with UV emitter.

The substrate to be coated is placed on the conveyor belt. The thermal transfer foil is unwound to the desired length, placed with the adhesive layer on the substrate to be coated and cut off. Substrate and film are fed into the platen press. The press is closed and the desired pressure is applied. In this case, the lacquer layer is transferred to the substrate. After opening the press, the coated substrate is moved out of the press and passed through the drying tunnel, causing the paint layer to harden. In this case, the carrier film can remain on the substrate and serve as a protective film. Alternatively, it is possible to separate the film in front of the UV channel.

For further details on this, reference is made in particular to FIGS EP 2078618 A2 and the explanations given there.

The following examples serve to illustrate the invention:

I. Feed Materials for Radiation Curable Composition

• Urethane acrylate diluted with 35% by weight dipropylene glycol diacrylate, functionality 2.0: Laromer® ^UA9065 from BASF SE
• Aliphatic urethane acrylate 1, diluted with 35% by weight of dipropylene glycol diacrylate: ^Laromer® UA19T from BASF SE
• Aliphatic urethane acrylate 2 diluted with 30% by weight of trimethylolpropane formal monoacrylate, functionality 1.7: Laromer® ^UA9033 from BASF SE
• Aliphatic urethane acrylate 3, diluted with 30% by weight of hexanediol diacrylate: ^Laromer® LR 8987 from BASF SE
• Polyester acrylate 1, functionality 3.3, hydroxyl number 70: Laromer® ^PE9084 from BASF SE
• Polyester acrylate 2, functionality 3.2, hydroxyl number 50: Laromer® ^PE9074 from BASF SE
• Polyester acrylate 3, functionality 3.1, hydroxyl number 70: Laromer® ^PE55F from BASF SE
• Polyester acrylate 4, functionality 2.5, hydroxyl number 60, blended with 20% by weight of tripropylene glycol diacrylate: ^Laromer® PE9045 from BASF SE
• Phenoxyethyl acrylate: ^Laromer® POEA from BASF SE
• Trimethylolpropane formal monoacrylate: ^Laromer® LR8887 from BASF SE
• Trimethylolpropane triacrylate: ^Laromer® TMPTA from BASF SE
• Dipropylene Glycol Diacrylate (DPGDA)
• Pyrogenic silica: ACE Matt TS 100 from Evonik Industries AG
• Silica-based matting agent (Syloid ED 80)
• Aluminum oxide: Alodur ZWSK F320/280 from Treibacher
• Corundum 1: Alodur F280 from Treibacher
• Corundum 2: Alodur F320 from Treibacher
• Synthetic silica: ^Syloid® RAD 2005 from Grace
• Synthetic, organically modified silica: Gasil ^® UV 70C
• Polyethersiloxane: Tego Glide 435 from Evonik Industries AG
• Deaerator concentrate: Tego Airex 920 from Evonik
• alpha-Hydroxyalkylphenone: ^Irgacure® 184 from BASF SE
• Acylphosphine oxide: ^Irgacure® 2100 from BASF SE
• Phenyl glyoxylate: ^Irgacure® MBF from BASF SE
• Triazine-based UV absorber: Mixture of 2-[4-[(2-Hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5 -triazine and 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine.
• UV stabilizer (HALS): mixture of bis(1,2,2,5,5-pentamethyl-4-piperidyl)sebacate 1-(methyl)-8-(1,2,2,5,5-pentamethyl- 4-piperidyl)sebacate

The following radiation-curable coating formulations 1 to 7 were prepared by mixing the raw materials mentioned above: Paint formulation 1: raw material Amount [% by weight] ¹⁾ Urethane acrylate diluted with 35% by weight dipropylene glycol diacrylate, functionality 2.0 30.0 Polyester acrylate 1, functionality 3.3 9.0 Trimethylolpropane formal monoacrylate 9.8 trimethylolpropane triacrylate 13.0 Aliphatic urethane acrylate 2 diluted with 30 8.5 % by weight of trimethylolpropane formal monoacrylate, functionality 1.7 aluminum oxide (corundum) 25.0 deaerator concentrate 0.5 Fumed silica 1.0 phenyl glyoxylate 1.6 acylphosphine oxide 0.4 alpha-hydroxyalkylphenone 1.0 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Urethane acrylate diluted with 35% by weight dipropylene glycol diacrylate, functionality 2.0 37.0 Aliphatic urethane acrylate 2 diluted with 30% by weight trimethylolpropane formal monoacrylate, functionality 1.7 24.7 phenoxyethyl acrylate 24.7 Synthetic silica 6.0 Synthetic, organically modified silica 2.5 Fumed silica 1.0 polyether siloxane 0.6 deaerator concentrate 0.5 phenyl glyoxylate 1.0 acylphosphine oxide 0.2 alpha-hydroxyalkylphenone 0.9 benzophenone 0.9 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ polyester acrylate 2 33.4 trimethylolpropane triacrylate 14.3 polyester acrylate 3 10.3 Trimethylolpropane formal monoacrylate 10.5 phenoxyethyl acrylate 11.0 polyester acrylate 4 10.0 deaerator concentrate 0.5 phenyl glyoxylate 1.6 acylphosphine oxide 0.4 alpha-hydroxyalkylphenone 1.0 1) based on the total weight of the composition raw material Amount [% by weight1 ¹⁾ Aliphatic urethane acrylate 3 diluted with 30% by weight hexanediol diacrylate 80 dipropylene glycol diacrylate 10 silicone defoamer 0.35 Silica-based matting agent 7.0 phenyl glyoxylate 1.3 acylphosphine oxide 1.35 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Urethane acrylate diluted with 35% by weight dipropylene glycol diacrylate, functionality 2.0 26.0 Aliphatic urethane acrylate 2 diluted with 30% by weight of trimethylolpropane formal monoacrylate 8.5 Polyester acrylate 1 8.0 Trimethylolpropane formal monoacrylate 7.0 phenoxyethyl acrylate 7.0 trimethylolpropane triacrylate 11.0 Silica-based matting agent 5.0 corundum 1 15.0 corundum 2 10.0 silicone defoamer 0.3 rheology additive 0.2 acylphosphine oxide 2.0 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Aliphatic urethane acrylate 1 diluted with 35% by weight dipropylene glycol diacrylate 34.0 Aliphatic urethane acrylate 2 diluted with 30% by weight of trimethylolpropane formal monoacrylate 11.5 Polyester acrylate 1 10.0 Trimethylolpropane formal monoacrylate 11.0 phenoxyethyl acrylate 10.0 trimethylolpropane triacrylate 14.0 Silica-based matting agent 7.0 silicone defoamer 0.3 acylphosphine oxide 2.0 1) based on the total weight of the composition raw material Amount [% by weight] ¹⁾ Aliphatic urethane acrylate 3 diluted with 30% by weight hexanediol diacrylate 77.0 hexanediol diacrylate 12.0 Silica-based matting agent 5.0 Triazine-based UV absorber 2.0 UV stabilizer 1.0 silicone defoamer 0.35 acylphosphine oxide 1.3 phenyl glyoxylate 1.3 1) based on the total weight of the composition

II. Feed Materials for Adhesive Composition

• Self-crosslinking, aqueous polyacrylate dispersion 1 (50% strength by weight): Acronal® ^A849S from BASF SE
• Self-crosslinking, aqueous multiphase polyacrylate dispersion 2 (48% strength by weight), minimum film-forming temperature 50° C.;
• Aqueous polyester urethane dispersion, 40% by weight, glass transition temperature < -50°C;
• Aqueous polyetherurethane acrylate dispersion 1 (40% by weight): Laromer® ^LR9005 from BASF SE
• Aqueous polyetherurethane acrylate dispersion 2 (40% strength by weight): ^Syntholux® 1014 W from Synthopol Chemie
• Aliphatic epoxy acrylate: ^Laromer® LR 8765 from BASF SE
• Polyethersiloxane emulsion: ^Tego® Wet 270 from Evonik Industries AG
• Polymeric fluorosurfactant: ^Tego® Twin from Evonik Industries AG
• Wetting Additive 1: Siloxane Gemini Surfactant
• Wetting Additive 2: Polyethersiloxane
• Carnauba wax dispersion: CA 30 from Münzing Liquid Technologies GmbH
• Modified polyethylene wax, aqueous dispersion: ^Aquamat® 270 from Byk Chemie GmbH
• Pyrogenic silica: ACE Matt TS 100, from Evonik Industries AG
• Micronized polyethylene wax: ^Aquaflour® 400 from Byk Chemie GmbH
• Synthetic silica: Sylysia from Finma Chemie
• Aqueous polyurethane dispersion: Ecrothan 90 from Ecronova Polymer GmbH
• Dimethylpolysiloxane: ^Tego® Glide 482 from Evonik Industries AG
• Styrene-acrylate copolymer: ^Acronal® S 813 from BASF SE
• Triethyl citrate: Citrofol Al from Jungbunzlauer GmbH
• alpha-Hydroxyalkylphenone: Irgacure ^® 184
• Acylphosphine Oxide: Irgacure ^® 2100
• Bisacylphosphine Oxide: ^Irgacure® 819 DW
• mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone;
• Defoamer: silicone-based emulsion;
• Thickener: Aqueous thickener solution (Vocaflex)
• Aqueous titanium dioxide paste: ^Luconyl® white 0022 from BASF SE

Adhesive composition 1 was prepared by mixing the components listed in the table below. Adhesive formulation 1: raw material Amount [% by weight] ¹⁾ Self-crosslinking aqueous polyacrylate dispersion 1 39.0 Aqueous polyetherurethane acrylate dispersion 1 16.4 Polyethersiloxane Emulsion 0.44 Polymeric fluorosurfactant 0.35 carnauba wax dispersion 1.20 Modified polyethylene wax 7.3 Fumed silica 1.5 Synthetic silica 1.3 Micronized polyethylene wax 1.7 polyurethane dispersion 13.0 dimethylpolysiloxane 0.4 Aliphatic epoxy acrylate 6.1 Styrene acrylate dispersion (50%) 4.4 triethyl citrate 1.75 alpha-hydroxyalkylphenone 1.0 acylphosphine oxide 0.7 benzophenone 0.85 butyl glycol 1.0 water 1.0 amino alcohol 0.17 1) based on the total weight of the composition

Adhesive formulation 2 was prepared by mixing the components listed in the table below. Adhesive formulation 2 raw material Amount [% by weight] ¹⁾ Self-crosslinking aqueous polyacrylate dispersion 2 30.5 Aqueous polyetherurethane acrylate dispersion 2 12.3 Aliphatic epoxy acrylate 6.0 Titanium Dioxide Paste 18.0 Polyethersiloxane Emulsion 0.5 Polymeric fluorosurfactant 0.4 carnauba wax dispersion 1.2 Modified polyethylene wax 5.8 Synthetic silica 3.5 polyurethane dispersion 11.0 Styrene acrylate dispersion (50%) 4.0 triethyl citrate 1.8 alpha-hydroxyalkylphenone 1.0 acylphosphine oxide 1.5 diacylphosphine oxide 0.5 butyl glycol 1.0 water 1.0 1) based on the total weight of the composition

Adhesive formulation 3 (not according to the invention) was prepared by mixing the components listed in the table below. Adhesive formulation 3 (not according to the invention) raw material Amount [% by weight] ¹⁾ Aqueous polyester urethane dispersion 57.5 Aqueous polyetherurethane acrylate dispersion 1 35.8 Wetting additive 1 0.1 Wetting additive 2 0.8 defoamer: 0.1 acylphosphine oxide 0.75 Mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone 2.0 thickener 0.05

Adhesive formulation 4 was prepared by mixing the components listed in the table below. Adhesive formulation 4 raw material Amount [% by weight] ¹⁾ Aqueous polyester urethane dispersion 40.0 Aqueous polyetherurethane acrylate dispersion 1 23.5 Self-crosslinking, aqueous multi-phase polyacrylate dispersion 2 23.5 Wetting additive 1 0.1 Wetting additive 2 0.8

III. Production of the film materials according to the invention:

In the following examples, a device was used for the irradiation, in which the coated or printed film was fed past a Ga-doped mercury lamp with a power of 120 W/cm at a defined feed rate.

For the films of Examples 1, 2 and 3, a UV-curable gravure ink based on an epoxy acrylate was used.

Example 1 (not according to the invention) Film for use as a colored lacquer in the furniture sector

Coating formulation 4 was applied in a layer thickness of 40 g/m ² to an uncolored polyethylene terephthalate carrier film in a layer thickness of 23 μm. The film coated in this way was guided past the Ga-doped mercury radiator at a feed rate of 30 m/min to gel the lacquer layer.

The UV-curable gravure printing ink was then applied to the gelled lacquer layer. For curing, the film printed in this way was passed again past the Ga-doped mercury radiator at a feed rate of 30 m/min.

Adhesive formulation 3 was then applied to the printed lacquer layer in a layer thickness of 15 g/m ² and dried thermally.

Example 2 (not according to the invention) Film for use as a colored lacquer in the furniture sector

Coating formulation 5 was applied in a layer thickness of 70 g/m ² to an uncolored polyethylene terephthalate carrier film in a layer thickness of 23 μm. The film coated in this way was guided past the Ga-doped mercury radiator at a feed rate of 30 m/min to gel the lacquer layer.

The UV-curable gravure printing ink was then applied to the gelled lacquer layer. For curing, the film printed in this way was passed again past the Ga-doped mercury radiator at a feed rate of 30 m/min.

Adhesive formulation 3 was then applied to the printed lacquer layer in a layer thickness of 15 g/m ² and dried thermally.

Coating formulation 6 was applied in a layer thickness of 40 g/m ² to an uncolored polyethylene terephthalate carrier film in a layer thickness of 23 μm. The film coated in this way was guided past the Ga-doped mercury radiator at a feed rate of 30 m/min to gel the lacquer layer.

Example 3 (not according to the invention) Film for use as a clear lacquer in the furniture sector

Adhesive formulation 3 was then applied to the printed lacquer layer in a layer thickness of 15 g/m ² and dried thermally.

Coating formulation 7 was applied in a layer thickness of 45 g/m ² to an uncolored polyethylene terephthalate carrier film in a layer thickness of 23 μm. The film coated in this way was guided past the Ga-doped mercury radiator at a feed rate of 30 m/min to gel the lacquer layer.

The UV-curable gravure printing ink was then applied to the gelled lacquer layer. For curing, the film printed in this way was passed again past the Ga-doped mercury radiator at a feed rate of 30 m/min.

Example 4 (not according to the invention) Film for outdoor use as a colored lacquer

Adhesive formulation 3 was then applied to the printed lacquer layer in a layer thickness of 15 g/m ² and dried thermally.

IV. Testing of the film materials: a) Checking the crosslinking of the adhesive layer

raw material Amount [% by weight] ¹⁾ defoamer: 0.1 acylphosphine oxide 1.0 phenyl glyoxylate 1.0 1) based on the total weight of the composition

The film from Example 3 was laminated to a beech wood panel using a heated roller (180° C., maximum object temperature 50° C.). The film laminated in this way was then irradiated through the film by passing the laminated side at a feed rate of 20 m/min to two UV lamps (mercury lamp and Ga-doped mercury lamp) each with an output of 120 W/cm.

The sample obtained in this way was analyzed by means of ATR-FTIR spectroscopy using a Nicolet FT-IR spectrometer (Nicolet 380) and a Golden ^Gate® probe head. Compared to a non-irradiated sample, there was a significant reduction in the absorption bands at 810 cm-1 (> 40%) and 1410 cm-1 (> 30%) that are characteristic of acrylate groups.

b) Testing the stability of the coating

• P1: Beständigkeit gegen Wassereinwirkung (24 h) nach DIN 68861-1:2011-01. Die Bewertung erfolgte auf einer Skala von 1 (schlecht) bis 5 (gut).
• P2: Beständigkeit gegen Ethanoleinwirkung (6 h) nach DIN 68861-1:2011-01. Die Bewertung erfolgte auf einer Skala von 1 (schlecht) bis 5 (gut).
• P3: Beständigkeit gegen Einwirkung von Ethylacetat (10 s) nach DIN 68861-1:2011-01. Die Bewertung erfolgte auf einer Skala von 1 (schlecht) bis 5 (gut).
• P4: Prüfung mit dem Hamberger Hobel: Hierzu wird ein münzähnlicher Prüfkörper in vorgegebenem Winkel mit variabler Kraft über die zu prüfende Oberfläche gezogen. Das Prüfgerät erlaubt eine stufenlose Einstellung der applizierten Kraft. Angegeben wird die Kraft in Newton bei der gerade noch keine Beschädigung der Oberfläche zu erkennen ist.
• P5: Kratzbeständigkeit im Diamant-Test nach EN 438-2:205. Angegeben ist der Zahlenwert der höchsten angewendeten Kraft, die keinen durchgehenden Oberflächenkratzer hinterlässt.
• P6: Der Gitterschnitttest erfolgte nach DIN EN ISO 2409:2013. Die Bewertung erfolgte auf einer Skala von GT 0 (gute Haftung) bis GT 5 (sehr starkes Abplatzen der Beschichtung).
• P7: Abriebbeständigkeit nach der Falling Sand Methode nach DIN EN 14354:2005-03
• P8: Abriebbeständigkeit nach der S24-Methode nach DIN 13329:2013-12

The following tests were carried out:

• P1: Resistance to water (24 h) according to DIN 68861-1:2011-01. The assessment was made on a scale from 1 (poor) to 5 (good).
• P2: Resistance to the effects of ethanol (6 h) according to DIN 68861-1:2011-01. The assessment was made on a scale from 1 (poor) to 5 (good).
• P3: Resistance to the effects of ethyl acetate (10 s) according to DIN 68861-1:2011-01. The assessment was made on a scale from 1 (poor) to 5 (good).
• P4: Testing with the Hamberger planer: For this purpose, a coin-like test piece is pulled over the surface to be tested at a specified angle with variable force. The test device allows a stepless adjustment of the applied force. The force in Newtons at which there is just no damage to the surface is given.
• P5: scratch resistance in the diamond test according to EN 438-2:205. The number given is the highest force applied that does not leave a continuous surface scratch.
• P6: The cross cut test was carried out according to DIN EN ISO 2409:2013. The evaluation was made on a scale from GT 0 (good adhesion) to GT 5 (very severe chipping of the coating).
• P7: Abrasion resistance according to the falling sand method according to DIN EN 14354:2005-03
• P8: Abrasion resistance according to the S24 method according to DIN 13329:2013-12

The results of tests P1 - P8 are summarized in Table P.

Sample 1:

The film from Example 1 was laminated to an MDF board using a heated roller (180° C., maximum object temperature 50° C.) with constant contact pressure. The sheet laminated in this way was then irradiated through the film by moving the laminated side past two UV lamps (mercury lamp and Ga-doped mercury lamp) with a power of 120 W/cm each at a feed rate of 20 m/min. The backing film was then removed.

Comparative sample V1:

For comparison purposes, the film from Example 1 was laminated to an MDF board using a heated roller (180° C., maximum object temperature 50° C.) with the same contact pressure, but no subsequent irradiation was carried out.

Sample 2:

The production took place analogously to the production of sample 1, the film from example 2 being used instead of the film from example 1.

Comparative sample V2:

The production took place analogously to the production of comparison sample C1, the film from example 2 being used instead of the film from example 1.

Sample 3:

The film from Example 3 was laminated to a beech wood panel using a heated roller (180° C., maximum object temperature 50° C.) with constant contact pressure. The sheet laminated in this way was then irradiated through the film by moving the laminated side past two UV lamps (mercury lamp and Ga-doped mercury lamp) with a power of 120 W/cm each at a feed rate of 20 m/min. The backing film was then removed.

Comparative sample V3:

For comparison purposes, the film from Example 3 was laminated to a beechwood panel using a heated roller (180° C., maximum object temperature 50° C.) with the same contact pressure, but no subsequent irradiation was carried out.

Sample 4:

The film from Example 43 was laminated to a PVC sheet using a heated roller (180° C., maximum object temperature 50° C.) with constant contact pressure. The sheet laminated in this way was then irradiated through the film by moving the laminated side past two UV lamps (mercury lamp and Ga-doped mercury lamp) with a power of 120 W/cm each at a feed rate of 15 m/min. The backing film was then removed.

Comparative sample V4:

For comparison purposes, the film from Example 4 was laminated to a PVC plate using a heated roller (180° C., maximum object temperature 50° C.) with the same contact pressure, but no subsequent irradiation was carried out. Table P: Results of tests P1 - P8 sample UV curing P1 p2 P3 P4 [N] P5 [N] P6 P7 [rpm ^-1 ] P8 [rpm ^-1 ] 1 Yes 5 5 5 20 1.2 GT0 nb nb 2 Yes 5 5 5 19 1.0 GT0 620 1600 3 Yes 5 5 5 18 1.1 GT0 nb nb 4 Yes 5 5 5 19 1.3 GT1 nb nb V1 no 4-5 5 5 13 0.7 GT5 nb nb v2 no 4-5 4-5 5 14 0.6 GT4 630 1550 V3 no 4 4 5 13 0.7 GT4 nb nb V4 no 5 5 5 13 0.7 GT3 nb nb

The results, which are not according to the invention, show that good adhesion can only be achieved if the adhesive layer contains a radiation-curable component which is crosslinked by exposure to UV radiation after lamination.

Claims (13)

1. A thermal transfer foil (1) comprising:

   a) a backing foil (2),

   b) at least one layer (3) of coating material arranged on the backing foil (2),

   c) at least one heat-sealable, polymeric adhesive layer (4),

   where the layer of coating material is based on a non-aqueous, radiation-curable, liquid composition which comprises at least 60% by weight, based on the total weight of the composition, of curable constituents selected from organic oligomers which have ethylenically unsaturated double bonds and mixtures of said oligomers with monomers which have at least one ethylenically unsaturated double bond,

   and where the heat-sealable polymeric adhesive layer (4) comprises at least one radiation-curable constituent which is selected from organic oligomers and polymers which have ethylenically unsaturated double bonds,

   where the adhesive layer (4) is based on at least two aqueous polymer dispersions, where at least one polymer dispersion comprises a UV-radiation-curable polymer in dispersed form, and where at least one other polymer dispersion comprises a self-crosslinking polymer in dispersed form.
2. The thermal transfer foil according to claim 1, wherein the radiation-curable composition which forms the layer of coating material comprises from 1.5 to 8 mols of ethylenically unsaturated double bonds per kg of the composition.
3. The thermal transfer foil according to any of the preceding claims, wherein the oligomers in the radiation-curable composition which forms the layer of coating material have an average of from 1.5 to 10, in particular from 2 to 8, ethylenically unsaturated double bonds per molecule.
4. The thermal transfer foil according to any of the preceding claims, wherein the ethylenically unsaturated double bonds in the oligomers and in the monomers of the radiation-curable composition which forms the layer of coating material take the form of acrylic or methacrylic groups.
5. The thermal transfer foil according to any of the preceding claims, wherein the oligomers of the radiation-curable composition which forms the layer of coating material are selected from the following: polyether (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, unsaturated polyester resins, and mixtures of these.
6. The thermal transfer foil according to any of the preceding claims, wherein the radiation-curable liquid composition comprises at least one photoinitiator which has an absorption band with a maximum λ_max in the range from 220 to 420 nm.
7. The thermal transfer foil according to any of the preceding claims, wherein the thickness of the layer (3) of coating material is from 10 to 120 µm.
8. The thermal transfer foil according to any of the preceding claims, which has a decorative layer between the layer (3) of coating material and the adhesive layer (4).
9. A process for the production of a thermal transfer foil according to any of the preceding claims, comprising:

   i. the application of the non-aqueous, radiation-curable, liquid composition, where a coating curable by high-energy radiation is obtained;

   ii. irradiation, by high-energy radiation, of the curable coating obtained in step i., where the layer (3) of coating material is obtained;

   iii. optionally application of a decorative layer to the curable coating or to the layer (3) of coating material; and

   iv. application of the heat-sealable, polymeric adhesive layer (4).
10. The process according to claim 9, where the irradiation of the coating curable by high-energy radiation takes place before the application of the adhesive layer and before the optional application of the decorative layer.
11. The process according to claim 9 or 110, where the manner of irradiation of the coating curable by high-energy radiation is such as to cause only partial polymerization of the ethylenically unsaturated double bonds comprised in the non-aqueous, radiation-curable, liquid composition.
12. A process for the coating of surfaces of articles, comprising the following steps:

    a) application of the thermal transfer foil (1) according to any of claims 1 to 8 with the adhesive layer to the surface to be coated;

    b) heat-sealing of the transfer foil, where a surface coated with the transfer foil is obtained;

    c) irradiation, with UV radiation or electron beams, of the surface coated with the transfer foil;

    d) optionally release of the backing foil (2).
13. The use of thermal transfer foils according to any of claims 1 to 8 for the dry coating of articles.