Method for transferring an embossed structure to the surface of a coating

Abstract

The present disclosure relates to a method for transferring an embossed structure to at least a part of a surface of a coating (B2), using a composite (F1B1) composed of a substrate (F1) and of an at least partially embossed and at least partially cured coating (B1), where the coating (B2) and the coating (B1) of the composite (F1B1) have embossed structures which are mirror images of one another. Also described herein is a composite (B2B1F1). Further described herein is a use of this composite for producing an at least partially embossed coating (B2) in the form of a free film or a composite (B2KF2) composed of a substrate (F2), at least one adhesive (K), and the coating (B2).

Claims

1. A method for transferring an embossed structure to at least a part of a surface of a coating (B2), using a composite (F1B1) composed of a substrate (F1) and of an at least partially embossed and at least partially cured coating (B1), where the coating (B2) and the coating (B1) of the composite (F1B1) have embossed structures which are mirror images of one another, the method comprising: (1) applying a coating composition (B2a) to at least a part of an at least partially embossed surface of a composite (B1F1) comprising the substrate (F1), and the at least partially embossed and at least partially cured coating (B1), to give a composite (B2aB1F1), and (2) (2) at least partially curing the applied coating composition (B2a) to give a composite (B2B1F1) comprising the substrate (F1), the at least partially embossed and at least partially cured coating (B1), and the at least partially cured coating (B2), and (3) removing the coating (B2) from the composite (B2B1F1) to restore the composite (B1F1) used in step (1), where the coating (B2), on its surface previously facing the coating (B1) within the composite (B2B1F1), has a negative image of the at least partially embossed surface of the coating (B1) of the composite (B1F1) used in step (1) and restored in that step, wherein: the coating (B2) in step (3) is obtained as a free film by peeling from the composite (B2B1F1) with additional restoration of the composite (B1F1), or the coating (B2) is obtained in step (3) in three stages in a form of a composite (B2KF2), the method further comprising: (3a) applying an adhesive (K) to at least a part of a surface of the composite (B2B1F1), on its side having the coating (B2), to give a composite (KB2B1F1), (3b) applying a substrate (F2) to the composite (KB2B1F1) obtained after stage (3a), to at least a part of its surface having the adhesive (K), or vice-versa, to give a composite (F2KB2B1F1), and (3c) peeling the composite (B1F1) from the composite (F2KB2B1F1) to give a composite (F2KB2), where the coating (B2) of this composite has on its surface at least partially the negative image of the at least partially embossed surface of the coating (B1) of the composite (B1F1), where the coating composition (B1a) used for producing the coating (B1) of the composite (B1F1) used in step (1) and restored in step (3) is a radiation-curable coating composition, wherein the radiation-curable coating composition (B1a) comprises at least one component (a) in an amount in a range from 40 to 95 wt %, at least one additive as component (b) in an amount in a range from 0.01 to 5 wt %, at least one photoinitiator as component (c) in an amount in a range from 0.01 to 15 wt %, and at least one component (d), comprising at least one carbon double bond, in an amount in a range from 0 to 45 wt %, where (i) the components (a), (b), (c), and (d) are each different from one another, (ii) the stated amounts of the components (a), (b), (c), and (d) are each based on a total weight of the coating composition (B1a), and (iii) the amounts of all components present in the coating composition (B1a) add up to 100 wt %, and where component (a) comprises at least three structural units, each different from one another or at least partially identical, of formula (I) ##STR00007## in which radicals R.sup.1 in each case independently of one another are a C.sub.2-C.sub.8 alkylene group, radicals R.sup.2 in each case independently of one another are H or methyl, and m each independently of one another are an integral parameter in a range from 1 to 15, but with proviso that m is at least 2 in at least one of the structural units of the formula (I) within the component (a).

2. The method as claimed in claim 1, wherein the coating (B2) is obtained as a free film by peeling from the composite (F2KB2) obtained after stage (3c).

3. The method as claimed in claim 1, wherein the at least partially embossed and at least partially cured coating (B1) of the composite (F1B1) used in step (1) has embossments in a micrometer and/or nanometer range.

4. The method as claimed in claim 1, wherein the composite (B1F1) used in step (1) is a composite composed of a film web (F1) and of a coating (B1) which is applied thereto and is at least partially embossed and at least partially cured.

5. The method as claimed in claim 1, wherein the composite (B1F1) used in step (1) and restored after step (3) is reusable and can be used repeatedly for transferring at least one embossed structure.

6. The method as claimed in claim 1, wherein the composite (F1B1) which is used in step (1) and which is composed of the substrate (F1) and of an at least partially embossed and at least partially cured coating (B1) is at least obtainable by (4) applying the radiation-curable coating composition (B1a) to at least a part of a surface of the substrate (F1), (5) at least partially embossing the radiation-curable coating composition (B1a), applied at least partially to the surface of the substrate (F1), by means of at least one embossing tool (P1) having at least one embossing die (p1), (6) at least partially curing the radiation-curable coating composition (B1a), applied to at least a part of the surface of the substrate (F1) and at least partially embossed, by radiation curing, to give a composite (F1B1) composed of substrate (F1) and of at least partially embossed and at least partially cured coating (B1), where throughout a duration of the at least partial curing the coating composition (B1a) is in contact with the at least one embossing die (p1) of the at least one embossing tool (P1), and (7) removing the composite (F1B1) from the embossing tool (P1).

7. The method as claimed in claim 1, wherein a solids content of the coating composition (B1a) is >90 wt %, based on a total weight of the coating composition (B1a).

8. The method as claimed in claim 1, wherein m is at least 2 in each of the at least three structural units of the formula (I) of component (a).

9. The method as claimed in claim 1, wherein a fraction of ether segments [OR.sup.1].sub.m present in the structural units of formula (I) in the component (a) is at least 35 wt %, based on a total weight of component (a).

10. A method for producing a coating (B2), embossed at least partially on one of its surfaces, in the form of a free film, using a composite (B2B1F1) comprising: a substrate (F1), an at least partially embossed and at least partially cured coating (B1), and an at least partially cured coating (B2) applied to (B1), where the coating (B1) is producible by at least partially curing a coating composition (B1a), applied to at least a part of a surface of the substrate (F1) and at least partially embossed, by radiation curing, where the coating composition (B1a) is a radiation-curable coating composition, wherein the coating composition (B1a) comprises: at least one component (a) in an amount in a range from 40 to 95 wt %, at least one additive as component (b) in an amount in a range from 0.01 to 5 wt %, at least one photoinitiator as component (c) in an amount in a range from 0.01 to 15 wt %, and at least one component (d), comprising at least one carbon double bond, in an amount in a range from 0 to 45 wt %, where (i) the components (a), (b), (c), and (d) are each different from one another, (ii) the stated amounts of the components (a), (b), (c), and (d) are each based on a total weight of the coating composition (B1a), and (iii) the amounts of all components present in the coating composition (B1a) add up to 100 wt %, and where component (a) comprises at least three structural units, each different from one another or at least partially identical, of formula (I) ##STR00008## wherein radicals R.sup.1 in each case independently of one another are a C.sub.2-C.sub.8 alkylene group, radicals R.sup.2 in each case independently of one another are H or methyl, and m each independently of one another are an integral parameter in a range from 1 to 15, but with proviso that m is at least 2 in at least one of the structural units of the formula (I) within the component (a).

11. A method for producing a composite (B2KF2) comprising a substrate (F2), at least one adhesive (K), and the coating (B2), using a composite (B2B1F1) comprising: a substrate (F1), an at least partially embossed and at least partially cured coating (B1), and an at least partially cured coating (B2) applied to (B1), where the coating (B1) is producible by at least partially curing a coating composition (B1a), applied to at least a part of a surface of the substrate (F1) and at least partially embossed, by radiation curing, where the coating composition (B1a) is a radiation-curable coating composition, wherein the coating composition (B1a) comprises: at least one component (a) in an amount in a range from 40 to 95 wt %, at least one additive as component (b) in an amount in a range from 0.01 to 5 wt %, at least one photoinitiator as component (c) in an amount in a range from 0.01 to 15 wt %, and at least one component (d), comprising at least one carbon double bond, in an amount in a range from 0 to 45 wt %, where (i) the components (a), (b), (c), and (d) are each different from one another, (ii) the stated amounts of the components (a), (b), (c) and (d) are each based on a total weight of the coating composition (B1a), and (iii) the amounts of all components present in the coating composition (B1a) add up to 100 wt %, and where component (a) comprises at least three structural units, each different f rom one another or at least partially identical, of formula (I) ##STR00009## wherein radicals R.sup.1 in each case independently of one another are a C.sub.2-C.sub.8 alkylene group, radicals R.sup.2 in each case independently of one another are H or methyl, and m each independently of one another are an integral parameter in a range from 1 to 15, but with proviso that m is at least 2 in at least one of the structural units of the formula (I) within the component (a).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows schematically a side view of an apparatus which can be used for implementing steps (4) to (7) of the method of the invention for producing a composite (F1B1), i.e., for producing a master film, and which is used for exemplary illustration of the method of the invention in relation to steps (4) to (7). By means of this apparatus it is possible to transfer structures such as microstructures and/or nanostructures, by means of an embossing tool (P1), to a substrate (F1) coated with (B1a), and, after curing, to produce a composite (F1B1)referred to as master film web (8) within FIG. 1which can be used as master film.

(2) The master transfer apparatus (30) shown in FIG. 1 operates according to a transfer principle wherein the desired negative structures are embossed directly, from a structured press cylinder or a press roll, which here is a master press cylinder (17), into the as yet uncured coating layer applied to the master film web (8b), corresponding to a composite (F1B1a), and this coating layer is then at least partially cured, with the structures applied thereon, curing taking place in situ by means of a lighting unit (3), to give the master film web (8)corresponding to a composite (F1B1). In this method, the film web (8a) used as substrate (F1) is drawn off from a film web roller (18), which contains only the carrier material, in other words the pure film without applied master coating, and is guided via various deflection roller systems and web tensioning systems, and is introduced into an embossing region (1) of the apparatus. There, the film web (8a) runs into a region between a pressuring roll (4) and the master press cylinder (17), and is provided outside the press region, in the coating application device (27), with the as yet uncured master coating layer (corresponding to the coating composition B1a). This application of coating corresponds to step (4) of the method of the invention. In the embossing region (1), in which the master film web (8b) with the as yet uncured master coating layer runs along a section of the outer surface of the master press cylinder (17), the microstructures and/or nanostructures embossed into the outer surface of the master press cylinder (17) are introduced as a negative image into the master coating layer of the master film web (8b) and are transferred. This corresponds to step (5) of the method of the invention. The master film web (8b) comprising the uncured coating composition (B1a) is then cured, in accordance with step (6) of the method of the invention. Curing here takes place at least partially in situ by irradiation with a lighting unit (3), by means of UV radiation, as for example by means of a unit formed of UV-LEDs. The resulting master film (8), in other words the composite (F1B1), is subsequently taken off, in accordance with step (7) of the method of the invention, from the outer surface of the master press cylinder (17), and the master film web (8) thus completed is spooled up onto a film web roller (19). The film web roller (19) then contains the completed master film web (8) with the master coating layer applied thereon and with the negative images of the microstructures and/or nanostructures embossed therein. This film web roller (19) can be removed and then used in an apparatus for implementing steps (1) to (3) of the method of the invention.

(3) Coating Compositions (B1a) and (B2a)

(4) Coating Composition (B1a)

(5) The coating composition (B1a) is a radiation-curable coating composition. The terms radiation-curable and radiation-curing are interchangeable here. The term radiation curing refers preferably to radical polymerization of polymerizable compounds by virtue of electromagnetic and/or particulate radiation, examples being (N)IR light in the wavelength range of =>400-1200 nm, preferably 700-900 nm, and/or UV light in the wavelength range of =100 to 400 nm, preferably of =200 to 400 nm and more preferably =250 to 400 nm, and/or electronic radiation in the range from 150 to 300 keV and more preferably with a radiation dose of at least 80, preferably 80 to 3000 mJ/cm.sup.2. Radiation curing is carried out with particular preference using UV radiation. The coating composition (B1a) may be cured by use of a suitable radiation source. Consequently, (B1a) is preferably a UV radiation-curing coating composition.

(6) The coating composition (B1a) comprises the at least one component (a) in an amount in a range from 40 to 95 wt %, preferably in a range from 45 or >45 to 90 wt %, more preferably in a range from 50 or >50 such as 55 to 85 wt %, very preferably in a range from 55 or 60 to 80 wt %, the at least one additive as component (b) in an amount in a range from 0.01 to 5 wt %, preferably in a range from 0.05 to 4.5 wt %, more preferably in a range from 0.1 to 4 wt %, very preferably in a range from 0.2 or 0.5 to 3 wt %, at least one photoinitiator as component (c) in an amount in a range from 0.01 to 15 wt %, preferably in a range from 0.1 to 12 wt %, more preferably in a range from 0.5 to 10 wt %, the at least one component (d), having at least one carbon double bond, in an amount in a range from 0 to 45 wt %, preferably in a range from 0 to 40 wt %, more preferably in a range from 0 to 35 wt %, very preferably in a range from 0 to 30 wt %, based in each case on the total weight of the coating composition (B1a).

(7) The presence of component (d) in the inventively employed coating composition (B1a) is therefore merely optional, as evident from the lower limit of 0 wt % indicated respectively above. With preference, the coating composition (B1a) contains component (d) in an amount of up to 30 wt %, based on the total weight of the coating composition (B1a).

(8) The components (a), (b), (c) and (d) are each different from one another. The stated amounts of the components (a), (b), (c) and (d) are based in each case on the total weight of the coating composition (B1a). The amounts of all the components present in the coating composition (B1a), i.e., the amounts of components (a), (b) and (c) and also optionally (d), and also of further components optionally present, in (B1a) add up to 100 wt %.

(9) Component (a) has at least three structural units, in each case different from one another or at least partially identical, of the formula (I)

(10) ##STR00003## in which the radicals R.sup.1 in each case independently of one another are a C.sub.2-C.sub.8 alkylene group, the radicals R.sup.2 in each case independently of one another are H or methyl, and the parameters m each independently of one another are an integral parameter in a range from 1 to 15, preferably in a range from 1 to 10, more preferably in a range from 1 to 8 or 2 to 8, very preferably in a range from 1 to 6 or 2 to 6, more particularly in a range from 1 to 4 or 2 to 4, but with the proviso that in at least one of the structural units of the formula (I) the parameter m is at least 2, preferably at least 3.

(11) Component (a) preferably has at least three identical structural units of the formula (I).

(12) The symbol

(13) ##STR00004##
here stands for a bond of the respective radical to the superordinate structure of the component (a)in other words, for example, for a bond of the radical [OR.sup.1].sub.mOC(O)C(R.sup.2)CH.sub.2 within the structural unit of the formula (I) to the superordinate structure of the component (a). This bonding takes place preferably via a linking of the oxygen atom of the radical [OR.sup.1].sub.mto a carbon atom of the superordinate radical. Similar comments apply in respect of the other structural units of the formula (I). It is clear that all at least three structural units of the formula (I) are combined within a single component, namely component (a).

(14) The component (a) preferably has precisely three structural units of the formula (I). In that case component (a) has precisely three functional (meth)acrylic groups. Alternatively, the structural units of the formulae (I) may each also be present more than three times as part of the component (a). In that case, for example component (a) may have more than three functional (meth)acrylic groups, as for example 4, 5 or 6 (meth)acrylic groups.

(15) The aforementioned radicals R.sup.1 each independently of one another are a C.sub.2-C.sub.8 alkylene group, preferably a C.sub.2-C.sub.6 alkylene group, more preferably a C.sub.2-C.sub.4 alkylene group, very preferably, each independently of one another, an ethylene group and/or a propylene group, especially preferably ethylene. In particular, all radicals R.sup.1 are ethylene. Suitable as propylene groups in each case are radicals R.sup.1 which have a structure CH.sub.2CH.sub.2CH.sub.2 or a structure CH(CH.sub.3)CH.sub.2 or a structure CH.sub.2CH(CH.sub.3). Particularly preferred in each case, however, is the propylene structure CH.sub.2CH.sub.2CH.sub.2.

(16) The parameters m, in each case independently of one another, are an integer in a range from 1 to 15. Since component (a) has at least three of the structural units of the formulae (I), and since the parameter m is at least 2 in at least one of the structural units of the formula (I), component (a) includes a total of at least four ether groups of the general formula OR.sup.1.

(17) With preference, component (a) in total has at least five, more preferably at least six, ether groups of the general formula OR.sup.1. The number of ether groups of the general formula OR.sup.1 within component (a) is situated preferably in a range from 4 to 18, more preferably in a range from 5 to 15, very preferably in a range from 6 to 12.

(18) The fraction of the ether segments [OR.sup.1].sub.m present in the structural units of the formula (I) of component (a) is preferably in total at least 35 wt %, more preferably at least 38 wt %, very preferably at least 40 wt %, more preferably still at least 42 wt %, more particularly at least 45 wt %, based in each case on the total weight of component (a).

(19) Component (a) preferably has a molecular weight (M.sub.n) in the range from 300 to 2000 g/mol, more preferably from 350 to 1500 g/mol, more particularly from 400 to 1000 g/mol.

(20) Particularly preferred for use as component (a) is at least one compound of the general formula (IVa) and/or (IVb),

(21) ##STR00005## in which, in each case independently of one another, R.sup.1 and R.sup.2 and also m have the definitions given above in connection with the structural units (I), including the preferred embodiments thereof stated above, and R.sup.3 is H, C.sub.1-C.sub.8 alkyl, OH or OC.sub.1-8 alkyl, more preferably is C.sub.1-C.sub.4 alkyl, OH or OC.sub.1-4 alkyl, and very preferably is C.sub.1-C.sub.4 alkyl or OH, or R.sup.3 is the radical [OR.sup.1].sub.mOC(O)C(R.sup.2)CH.sub.2, in which R.sup.1, R.sup.2 and m have the definitions stated above in connection with the structural unit (I), including the preferred embodiments thereof stated above.

(22) Very particular preference is given to the use as component (a) of at least one compound of the general formula (IVa) in which the radicals R.sup.1 each independently of one another are a C.sub.2-C.sub.8 alkylene group, the radicals R.sup.2 each independently of one another are H or methyl, the parameters m, in each case independently of one another, are an integral parameter in a range from 1 to 15, preferably in a range from 1 to 10, more preferably in a range from 1 to 8 or 2 to 8, very preferably in a range from 1 to 6 or 2 to 6, more particularly in a range from 1 to 4 or 2 to 4, but with the proviso that, in at least one and preferably in all of the structural units of the formula (I), the parameter m is at least 2. R.sup.3 is C.sub.1-C.sub.8 alkyl, OH or OC.sub.1-8 alkyl, more preferably C.sub.1-C.sub.4 alkyl, OH or OC.sub.1-4 alkyl, very preferably C.sub.1-C.sub.4 alkyl or OH.

(23) Especially preferred for use as component (a) are (meth)acrylates of neopentyl glycol, trimethylolpropane, trimethylolethane or pentaerythritol with a total of 4-fold to 20-fold alkoxylation, or of 4-fold to 12-fold alkoxylation, such as ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, neopentyl glycol, trimethylolpropane, trimethylolethane or pentaerythritol. The most preferred are corresponding (meth)acrylates deriving from correspondingly alkoxylated trimethylolpropane. Products of these kinds are available commercially and are sold for example under the designations Sartomer SR 499 and Sartomer SR 502 and also Sartomer SR 415 and Sartomer SR 9035 and also Sartomer SR 501. In the sense of the present invention, the term (meth)acrylic or (meth)acrylate embraces not only methacrylic but also acrylic and not only methacrylate but also acrylate, respectively.

(24) Aside from the optional component (d), the coating composition (B1a) preferably contains no component which has only exactly one or only exactly two ethylenically unsaturated groups such as (meth)acrylic groups. Where (B1a) has no component (d), therefore, (B1a) preferably contains no component which has only precisely one or only precisely two ethylenically unsaturated groups such as (meth)acrylic groups.

(25) Component (b) is an additive. The concept of the additive is known to the skilled person, from Rmpp Lexikon, Lacke und Druckfarben, Thieme Verlag, 1998, page 13, for example. A preferred component (b) used is at least one rheology additive. This term as well is known to the skilled person, from Rmpp Lexikon, Lacke und Druckfarben, Thieme Verlag, 1998, page 497, for example. The terms rheology additive, rheological additive and rheology assistant are interchangeable here. The additive used as component (b) is preferably selected from the group consisting of flow control agents, surface-active agents such as surfactants, wetting agents and dispersants, and also thickeners, thixotropic agents, plasticizers, lubricity and antiblocking additives, and mixtures thereof. These terms are likewise known to the skilled person, from Rmpp Lexikon, Lacke und Druckfarben, Thieme Verlag, 1998, for example. Flow control agents are components which by lowering the viscosity and/or surface tensions help coating compositions to form films which flow out evenly. Wetting agents and dispersants are components which lower the surface tension or, generally, the interfacial tension. Lubricity and antiblocking additives are components which reduce mutual sticking (blocking).

(26) Examples of commercially available additives are the products Efka SL 3259, Byk 377, Tego Rad 2500, Tego Rad 2800, Byk 394, Byk-SILCLEAN 3710, Silixan A250, Novec FC 4430 and Novec FC 4432.

(27) Preferred for use as additive (b) is at least one poly(meth)acrylate and/or at least one siloxane such as at least one oligosiloxane and/or polysiloxane and/or at least one fluorine-containing polymer such as a fluorine-containing, preferably aliphatic polyester. Particularly preferred as component (b) are siloxanes. Especially preferred for use are silicone (meth)acrylates.

(28) For the curing by means of (N) IR and/or UV light, the coating composition (B1a) comprises at least one photoinitiator as component (c). This photoinitiator can be broken down, by light of the irradiated wavelength, into radicals, which are able in turn to initiate a radical polymerization. In the case of curing with electronic radiation, conversely, there is no need for the presence of such photoinitiators. The coating composition (B1a) preferably includes at least one photoinitiator as component (c) which can be broken down, by light of the irradiated wavelength, into radicals which are able in turn to initiate a radical polymerization.

(29) Photoinitiators such as UV photoinitiators are known to the skilled person. Examples of those contemplated include phosphine oxides, benzophenones, -hydroxyalkyl aryl ketones, thioxanthones, anthraquinones, acetophenones, benzoins and benzoin ethers, ketals, imidazoles or phenylglyoxylic acids and mixtures thereof.

(30) Phosphine oxides are, for example, monoacyl- or bisacylphosphine oxides, as for example 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphinate or bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Benzophenones are, for example, benzophenone, 4-aminobenzophenone, 4,4-bis(dimethylamino)benzophenone, 4-phenylbenzophenone, 4-chlorobenzophenone, Michler's ketone, o-methoxybenzophenone, 2,4,6-trimethylbenzophenone, 4-methylbenzophenone, 2,4-dimethyl-benzophenone, 4-isopropylbenzophenone, 2-chlorobenzophenone, 2,2-dichlorobenzophenone, 4-methoxybenzophenone, 4-propoxybenzophenone or 4-butoxybenzophenone; -hydroxyalkyl aryl ketones are, for example, 1-benzoylcyclohexan-1-ol (1-hydroxycyclohexyl phenyl ketone), 2-hydroxy-2,2-dimethylacetophenone (2-hydroxy-2-methyl-1-phenylpropan-1-one), 1-hydroxyacetophenone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one or a polymer containing in copolymerized form 2-hydroxy-2-methyl-1-(4-isopropen-2-ylphenyl)-propan-1-one. Xanthones and thioxanthones are, for example, 10-thioxanthenone, thioxanthen-9-one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4-diethyl-thioxanthone, 2,4-diisopropylthioxanthone, 2,4-dichlorothioxanthone or chloroxanthenone; anthraquinones are, for example, -methylanthraquinone, tert-butylanthraquinone, anthraquinonecarboxylic esters, benz[de]anthracen-7-one, benz[a]anthracene-7,12-dione, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone or 2-amylanthraquinone. Acetophenones are, for example, acetophenone, acetonaphthoquinone, valerophenone, hexanophenone, -phenylbutyrophenone, p-morpholinopropiophenone, dibenzosuberone, 4-morpholino-benzophenone, p-diacetylbenzene, 4-methoxyacetophenone, -tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone, 1,3,4-triacetylbenzene, 1-acetonaphthone, 2-acetonaphthone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,2-dimethoxy-1,2-diphenylethan-2-one or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one. Benzoins and benzoin ethers are, for example, 4-morpholinodeoxybenzoin, benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether or 7H-benzoin methyl ether. Ketals are, for example, acetophenone dimethyl ketal, 2,2-diethoxyacetophenone, or benzil ketals, such as benzil dimethyl ketal. Photoinitiators which can also be used are, for example, benzaldehyde, methyl ethyl ketone, 1-naphthaldehyde, triphenylphosphine, tri-o-tolylphosphine or 2,3-butanedione. Typical mixtures comprise, for example, 2-hydroxy-2-methyl-1-phenylpropan-2-one and 1-hydroxycyclohexyl phenyl ketone, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone and 1-hydroxycyclohexyl phenyl ketone, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzophenone and 4-methylbenzophenone or 2,4,6-trimethylbenzophenone and 4-methylbenzophenone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

(31) Preferred among these photoinitiators are 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, bis(2,4,6-trimethyl-benzoyl)phenylphosphine oxide, benzophenone, 1-benzoyl-cyclohexan-1-ol, 2-hydroxy-2,2-dimethylacetophenone and 2,2-dimethoxy-2-phenylacetophenone. Preferably, therefore, at least one such photoinitiator is used as component (c). Component (c) is different from components (a), (b) and (d). Commercially available photoinitiators are, for example, the products Irgacure 184, Irgacure 500, Irgacure TPO, Irgacure TPO-L and Lucirin TPO and also Darocure 1173 from BASF SE.

(32) As mentioned above, the use of the at least one component (d) is only optional. Component (d) has at least one, preferably terminal, carbon double bond. This is preferably a (meth)acrylic group. Component (d) preferably has one or two ethylenically unsaturated groups such as, for example, one or two or three or else more (meth)acrylic groups. It is also possible for two or more different components (d) to be used.

(33) Examples of component (d) are mono-, di-, and/or tri-functional (meth)acrylic esters such as ethylene glycol di(meth)acrylate, 1,2-propanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,1-, 1,2-, 1,3- and 1,4-cyclohexanedimethanol di(meth)acrylate, 1,2-, 1,3- or 1,4-cyclohexanediol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane penta- or hexa(meth)acrylate, pentaerythritol tri- or tetra(meth)acrylate, glyceryl di- or tri(meth)acrylate, and also di- and poly(meth)acrylates of sugar alcohols, such as for example of sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol or isomalt, 2-phenoxyethyl (meth)acrylate, ethyl diglycol (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, trimethylolpropane formal mono(meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate and also lauryl, stearyl, isodecyl, octyl and decyl (meth)acrylate, esters of ,-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, with alcohols having 1 to 20 carbon atoms, preferably optionally hydroxy-substituted alkanols having 1 to 20 carbon atoms, e.g., methyl (meth)acrylic acid ester, ethyl (meth)acrylic acid ester, n-butyl (meth)acrylic acid ester, 2-ethylhexyl (meth)acrylic acid ester, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate.

(34) Especially preferred components (d) are 1,4-butanediol di(meth)acrylate and 1,6-hexanediol di(meth)acrylate and also tricyclodecanedimethanol di(meth)acrylate.

(35) As component (d) it is also possible, additionally or alternatively, to use at least one polyester, polyether, carbonate, epoxide, poly(meth)acrylate and/or urethane (meth)acrylate, and/or unsaturated polyester resin.

(36) Urethane (meth)acrylates are obtainable, for example, by reaction of polyisocyanates with hydroxyalkyl (meth)acrylates and optionally chain extenders such as diols, polyols, diamines, polyamines or dithiols or polythiols. Urethane (meth)acrylates dispersible in water without adding emulsifiers additionally contain ionic and/or nonionic hydrophilic groups, which are introduced into the urethane through synthesis components such as hydroxycarboxylic acids, for example. Such urethane (meth)acrylates contain essentially the following as synthesis components: (a) at least one organic aliphatic, aromatic or cycloaliphatic di- or polyisocyanate, as for example at least one of the polyisocyanates described above in connection with the two-component coating materials, (b) at least one compound having at least one isocyanate-reactive group, preferably one of the hydroxyl-bearing monomers described above in connection with the polyacrylate polyols, and at least one radically polymerizable unsaturated group, and (c) optionally at least one compound having at least two isocyanate-reactive groups, as for example one of the polyhydric alcohols described above in connection with the polyesterols.

(37) The urethane (meth)acrylates preferably have a number-average molar weight M.sub.n of 200 to 20 000, more particularly of 500 to 10 000, very preferably of 600 to 3000 g/mol (determined by gel permeation chromatography with tetrahydrofuran and polystyrene as standard). The urethane (meth)acrylates contain preferably from 1 to 5, more preferably from 2 to 4 mol of (meth)acrylic groups per 1000 g of urethane (meth)acrylate.

(38) Epoxide (meth)acrylates are obtainable by reaction of epoxides with (meth)acrylic acid. Examples of epoxides contemplated include epoxidized olefins, aromatic glycidyl ethers or aliphatic glycidyl ethers, preferably those of aromatic or aliphatic glycidyl ethers. Examples of possible epoxidized olefins include ethylene oxide, propylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, vinyloxirane, styrene oxide or epichlorohydrin; ethylene oxide, propylene oxide, isobutylene oxide, vinyloxirane, styrene oxide or epichlorohydrin are preferred, ethylene oxide, propylene oxide or epichlorohydrin are particularly preferred, and ethylene oxide and epichlorohydrin are especially preferred. Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol/dicyclopentadiene, e.g., 2,5-bis[(2,3-epoxypropoxy)phenyl]octahydro-4,7-methano-5H-indene, tris[4-(2,3-epoxypropoxy)phenyl]methane isomers, phenol-based epoxy novolacs and cresol-based epoxy novolacs. Aliphatic glycidyl ethers are, for example, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,1,2,2-tetrakis[4-(2,3-epoxypropoxy)phenyl]ethane, diglycidyl ethers of polypropylene glycol (,-bis(2,3-epoxypropoxy)poly(oxypropylene) (and of hydrogenated bisphenol A (2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane)). The epoxide (meth)acrylates preferably have a number-average molar weight M.sub.n of 200 to 20 000, more preferably of 200 to 10 000 g/mol and very preferably of 250 to 3000 g/mol; the amount of (meth)acrylic groups is preferably 1 to 5, more preferably 2 to 4, per 1000 g of epoxide (meth)acrylate (determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran as eluent).

(39) (Meth)acrylated poly(meth)acrylates are the corresponding esters of ,-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, more preferably of acrylic acid, with polyacrylate polyols, obtainable by esterifying poly(meth)acrylate polyols with (meth)acrylic acid. The polyacrylate polyols may for example be those as described above in connection with the two-component coating materials.

(40) Carbonate (meth)acrylates are available with various functionalities. The number-average molecular weight M.sub.n of the carbonate (meth)acrylates is preferably less than 3000 g/mol, more preferably less than 1500 g/mol, very preferably less than 800 g/mol (determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran solvent). The carbonate (meth)acrylates are obtainable in a simple way by transesterification of carbonic esters with polyhydric, preferably dihydric, alcohols (diols, e.g., hexanediol) and subsequent esterification of the free OH groups with (meth)acrylic acid or else transesterification with (meth)acrylic esters, as described for example in EP 0 092 269 A1. They are also obtainable by reaction of phosgene, urea derivatives with polyhydric alcohols, dihydric alcohols for example. Also conceivable are (meth)acrylates of polycarbonate polyols, such as the reaction product of one of the stated diols or polyols and a carbonic ester and also a hydroxyl-containing (meth)acrylate. Examples of suitable carbonic esters are ethylene, 1,2- or 1,3-propylene carbonate, dimethyl, diethyl or dibutyl carbonate. Examples of suitable hydroxyl-containing (meth)acrylates are 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, glyceryl mono- and di(meth)acrylate, trimethylolpropane mono- and di(meth)acrylate and also pentaerythritol mono-, di- and tri(meth)acrylate. With preference, the carbonate (meth)acrylates are aliphatic carbonate (meth)acrylates.

(41) Unsaturated polyester resins are preferably synthesized from the following components: (a1) maleic acid or derivatives thereof, (a2) at least one cyclic dicarboxylic acid or derivatives thereof, (a3) at least one aliphatic or cycloaliphatic diol.

(42) Derivatives here refer preferably to the relevant anhydrides in monomeric or else polymeric form, monoalkyl or dialkyl esters, preferably mono- or di-C.sub.1-C.sub.4 alkyl esters, more preferably monomethyl or dimethyl esters or the corresponding monoethyl or diethyl esters, additionally, monovinyl and divinyl esters, and also mixed esters, preferably mixed esters with different C.sub.1-C.sub.4 alkyl components, more preferably mixed methyl ethyl esters.

(43) If (B1a) includes a component (d), that component is preferably at least one urethane (meth)acrylate.

(44) The coating composition (B1a) may comprise at least one further component (e), different from the components (a) to (d), such as, for example, fillers, pigments, thermally activatable initiators such as, for example, potassium peroxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate or benzopinacol, cumene hydroperoxide, dicumyl peroxide, tert-butyl perbenzoate, silylated pinacols, hydroxyl-containing amine N-oxides, such as 2,2,6,6-tetramethylpiperidine-N-oxyl and 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and organic solvents, and also stabilizers. Preferably, however, there are no organic solvents included in (B1a). Component (e) may be present in an amount in a range from 0 to 15 wt %, preferably in a range from 0 to 12 wt %, more preferably in a range from 0 to 10 wt % in (B1a), based in each case on the total weight of the coating composition (B1a).

(45) The solids content of the coating composition (B1a) is preferably 80 wt %, more preferably 90 wt %, very preferably 95 wt %, more particularly 98 or 99 wt %, most preferably 100 wt %, based in each case on the total weight of the coating composition (B1a). The solids content here is determined by the method described below.

(46) The coating composition (B1a) preferably contains no thiols, and especially no trimethylolpropane tris(3-mercaptopropionate).

(47) The double bond conversion of the at least partially cured coating (B1) obtained from (B1a) is preferably at least 70%, more preferably at least 75%, more preferably still at least 80%, very preferably at least 85%, more particularly at least 90%.

(48) Coating Composition (B2a)

(49) Any kind of coating composition may be employed as coating composition (B2a) in step (1) of the method of the invention. The coating composition (B2a) may be a physically drying, thermally curable, chemically curable and/or radiation-curable coating composition (B2a). With preference, the coating composition (B2a) is a chemically curable, a thermally curable and/or radiation-curable coating composition, more preferably a radiation-curable coating composition. Accordingly, the at least partial curing as per step (3) takes place preferably by means of radiation curing. The coating composition (B2a) may be identical to the coating composition (B1a). Preferably, however, (B2a) is different from (B1a). (B2a) is preferably constructed from the alike, but not the same, components (a) to (e) also used in the preparation of (B1a), although the quantity provisos relating to (B1a) do not have to apply to (B2a).

(50) Physical drying here refers preferably to the simple evaporation of solvent (s) to form the coating (B2). Thermal curing here preferably entails a curing mechanism which is attributable to a temperature above room temperature (>23 C.). This may be, for example, the formation of radicals or ions, preferably radicals from an initiator which breaks down at the elevated temperatures and so initiates a radical or ionic polymerization. Examples of such thermally activatable initiators are those which have a half-life at 80 C. of less than 100 hours. Chemical curing refers preferably to the reaction of at least two different and mutually complementary reactive functional groups, in the manner, for example, of a polycondensation such as a reaction of an OH group with a COOH group, or of a polyaddition (reaction of an NCO group with an OH or amino group).

(51) If the coating composition (B2a) is a physically drying, thermally curable and/or chemically curable coating composition, it is prepared using, as binder, at least one customary polymer known to the skilled person. This binder then preferably has crosslinkable functional groups. Any customary crosslinkable functional group known to the skilled person is suitable in this context. More particularly, the crosslinkable functional groups are selected from the group consisting of hydroxyl groups, amino groups, carboxylic acid groups, isocyanates, polyisocyanates and epoxides. The polymers are preferably curable or crosslinkable exothermically or endothermically, preferably in a temperature range from 20 C. up to 250 C., or from 18 C. to 200 C. Especially suitable as polymers are at least one polymer selected from the group consisting of polyurethanes, polyethers, polyesters, polyamides, polyureas, polyvinyl chlorides, polystyrenes, polycarbonates, poly(meth)acrylates, epoxy resins, phenol-formaldehyde resins, melamine-formaldehyde resins. These polymers may in particular be OH-functional. In that case they may be subsumed by the general term polyols. Such polyols may for example be polyacrylate polyols, polyester polyols, polyether polyols, polyurethane polyols, polyurea polyols, polyester-polyacrylate polyols, polyester-polyurethane polyols, polyurethane-polyacrylate polyols, polyurethane-modified alkyd resins, fatty acid-modified polyester-polyurethane polyols, and also mixtures of the stated polyols. Preferred are polyacrylate polyols, polyester polyols and polyether polyols.

(52) It is possible here to use at least one polymer which is cured with participation of isocyanate and/or oligomerized isocyanate groups, very preferably at least one corresponding polyurethane and/or at least one corresponding polyurea (e.g., what are called polyaspartic binders). Polyaspartic binders are components which are converted from reaction of amino-functional compounds, especially secondary amines, with isocyanates. If at least one polyurethane is used, then those suitable especially are polyurethane-based resins which are preparable by a polyaddition reaction between hydroxyl-containing components such as polyols and at least one polyisocyanate (aromatic and aliphatic isocyanates, di-, tri- and/or polyisocyanates). Customarily here a stoichiometric reaction of the OH groups in the polyols with the NCO groups in the polyisocyanates is required. However, the stoichiometric ratio to be used can also be varied, since the polyisocyanate can be added to the polyol component in amounts such that there may be an over crosslinking or an under crosslinking. If epoxy resins are used, i.e. epoxide-based resins, then those suitable are preferably epoxide-based resins which are prepared from glycidyl ethers which have terminal epoxide groups and, within the molecule, hydroxyl groups as functional groups. These are preferably reaction products of bisphenol A and epichlorohydrin and/or of bisphenol F with epichlorohydrin, and mixtures thereof, which are also used in the presence of reactive diluents. The curing or crosslinking of such epoxide-based resins is accomplished customarily by a polymerization of the epoxide groups of the epoxide ring, by a polyaddition reaction in the form of an addition reaction of other reactive compounds, as hardeners, in stoichiometric amounts with the epoxide groups, in which case, accordingly, the presence of one active hydrogen equivalent per epoxide group is required (i.e., one H-active equivalent is needed for curing per epoxide equivalent), or by a polycondensation via the epoxide groups and the hydroxyl groups. Examples of suitable hardeners are polyamines, especially (hetero)aliphatic, (hetero)aromatic and (hetero)cycloaliphatic polyamines, polyamidoamines, polyaminoamides, and also polycarboxylic acids and their anhydrides.

(53) The concept of radiation curing has already been described above in connection with the coating composition (B1a). The coating composition (B2a) may be cured by use of a radiation source, preferably by using UV radiation. Preferably, therefore, (B2a) is a UV radiation-curing coating composition.

(54) (B2a) preferably therefore has unsaturated carbon double bonds, more preferably (meth)acrylic groups. For this purpose, the coating composition (B2) may comprise any of the components identified above in connection with (B1a) and subsumable under the components (a) and (d) of (B1a), such as, in particular, polyester, polyether, carbonate, epoxide, poly(meth)acrylate and/or urethane (meth)acrylates and/or at least one unsaturated polyester resin and/or mono-, di- and/or tri-functional (meth)acrylic esters.

(55) On curing by means of (N)IR and/or UV light, the coating composition (B2a) preferably comprises at least one photoinitiator which is able to be broken down into radicals by light of the irradiated wavelength, these radicals then being able to initiate a radical polymerization. In the case of curing with electronic radiation, in contrast, the presence of such photoinitiators is not necessary. As photoinitiators it is possible to use the same components in the same quantities as stated above in connection with component (c) of the coating composition (B1a).

(56) The coating composition (B2a) may comprise at least one further additive, moreover. In that case it is possible to use the same components in the same amounts as identified above in connection with the components (b) and (e) of the coating composition (B1a).

(57) The coating composition used as coating composition (B2a) is more preferably one having (meth)acrylic groups. With preference this coating composition (B2a) comprises at least one urethane (meth)acrylate. Preferably, moreover, it includes at least one photoinitiator.

(58) Composite (B2B1F1) of the Invention

(59) A further subject of the present invention, moreover, is a composite (B2B1F1) which is composed of a substrate (F1), of an at least partially embossed and at least partially cured coating (B1), and of a coating (B2) applied to (B1) and at least partially cured, where the coating (B1) is producible by at least partially curing a coating composition (B1a), applied to at least a part of a surface of the substrate (F1) and at least partially embossed, by radiation curing, where the coating composition (B1a) is a radiation-curable coating composition wherein the coating composition (B1a) comprises at least one component (a) in an amount in a range from 40 to 95 wt %, at least one additive as component (b) in an amount in a range from 0.01 to 5 wt %, at least one photoinitiator as component (c) in an amount in a range from 0.01 to 15 wt %, and at least one component (d), comprising at least one carbon double bond, in an amount in a range from 0 to 45 wt %, where (i) the components (a), (b), (c), and (d) are each different from one another, (ii) the stated amounts of the components (a), (b), (c), and (d) are each based on the total weight of the coating composition (B1a), and (iii) the amounts of all components present in the coating composition (B1a) add up to 100 wt %, and where component (a) comprises at least three structural units, each different from one another or at least partially identical, of the formula (I)

(60) ##STR00006## in which the radicals R.sup.1 in each case independently of one another are a C.sub.2-C.sub.8 alkylene group, the radicals R.sup.2 in each case independently of one another are H or methyl, and the parameters m each independently of one another are an integral parameter in a range from 1 to 15, but with the proviso that the parameter m is at least 2 in at least one of the structural units of the formula (I) within the component (a).

(61) All preferred embodiments described hereinabove in connection with the method of the invention, especially in connection with the coating compositions (B1a) and (B2a) used therein and with the substrate (F1) and also with the coatings (B1) and (B2), are also preferred embodiments in relation to the composite (B2B1F1) of the invention.

(62) The composite (B1F1) of this composite (B2B1F1) is obtainable preferably by implementation of the above-described method steps (4) to (7).

(63) The composite (B2B1F1) is obtainable preferably by implementation of the above-described method steps (1) and (2).

(64) The substrate (F1) is preferably a film web, more preferably a continuous film web.

Uses

(65) A further subject of the present invention is a use of the composite (B2B1F1) of the invention for producing a coating (B2), at least partially embossed on one of its surfaces, in the form of a free film, or for producing a composite (B2KF2) composed of a substrate (F2), at least one adhesive (K), and the coating (B2). This composite (B2KF2) is obtained preferably by traversal of the method stages (3a), (3b), and (3c), specifically by (3a) applying an adhesive (K) to at least a part of the surface of the composite (B2B1F1), on its side having the coating (B2), to give a composite (KB2B1F1), (3b) applying a substrate (F2) to the composite (KB2B1F1) obtained after stage (3a), to at least a part of its surface having the adhesive (K), or vice-versa, to give a composite (F2KB2B1F1), and (3c) peeling the composite (B1F1) from the composite (F2KB2B1F1) to give a composite (F2KB2), where the coating (B2) of this composite has on its surface at least partially the mirror image of the at least partially embossed surface of the coating (B1) of the composite (B1F1).

(66) All preferred embodiments described hereinabove in connection with the method of the invention and the composite (F1B1) and (B2B1F1) of the invention are also preferred embodiments in relation to the aforementioned uses.

(67) The coating composition (B2a) here is preferably a radiation-curable coating composition.

Methods of Determination

(68) 1. Determining the Nonvolatile Fraction

(69) The nonvolatile fraction (the solids or solids content) is determined according to DIN EN ISO 3251 (date: June 2008). The method involves weighing out 1 g of sample into an aluminum tray that has been dried beforehand and drying the sample in a drying cabinet at 125 C. for 60 minutes, cooling it in a desiccator, and then reweighing it. The residue, relative to the total amount of sample employed, corresponds to the nonvolatile fraction.

(70) 2. Determining the Modeling Accuracy

(71) The modeling accuracy is determined by means of a commercial atomic force microscope (AFM) and using a commercial cantilever. By means of AFM it is possible accordingly to compare, for example, the surface topography of a defined lattice structure such as that of the embossing tool P1, having a depth of 140 nm, for example, and a period of 430 nm, for example, with the surface topography of a master film (B1F1) after embossing. In this case the embossing tool is deliberately damaged at a particular site in order to define a reference point. By means of this reference point it is possible to investigate and compare with one another the same regions of the reference and of the replication. The modeling accuracy defines how accurately a particular reference structure can be transferred, such as from the embossing tool P1 to a master film (B1F1), for example. If, for example, the investigated region of the embossing tool P1 features a lattice structure having a depth of 140 nm, then this reference depth is compared with the corresponding height of the structure determined on the master film (B1F1). The percentage change, corresponding here to the modeling accuracy, is defined as:

(72) $h=100*\left(1-\frac{h_m}{h_r}\right)$

(73) h corresponds here to the percentage change, h.sub.m to the height of the structure in the investigated region of the master film, and h.sub.r to the corresponding depth of the structure of the investigated region of the embossing tool. This percentage change, in other words the modeling accuracy, is also referred to as contraction. The smaller the values of h, the better the modeling accuracy.

(74) 3. Determining the Flow Time

(75) The flow time is determined in accordance with DIN EN ISO 2431 (date: March 2012). The method involves determining the flow time by means of a 4 mm flow cup (No. 4) at room temperature (20 C.).

(76) 4. Determining the Double Bond Conversion

(77) The double bond conversion (DB conversion) is determined by ATR-IR spectroscopy after curing of the sample under investigation. With the technique of ATR-IR spectroscopy, an IR spectrum is recorded at the site of contact of a round reflection crystal with the substrate. The contact site has a diameter of around 200 m and the reflection crystal used is a germanium crystal.

(78) The starting material used for calculating the double bond conversion comprises the corresponding wet specimens of the sample. The DB conversion is calculated by way of the decrease in intensity of the band at 810 cm.sup.1. A band used for standardization is an ester band at 1730 cm.sup.1. The percentage double bond conversion is calculated by the following formula:

(79) $\mathrm{DB}-\mathrm{conversion}=100*\left(1-\frac{I_{810\mathrm{cm}-1}}{I_{\mathrm{Ref}-810\mathrm{cm}-1}}\right)$

(80) Here, I.sub.810cm-1 is the standardized intensity at 810 cm.sup.1 of the cured layer, and I.sub.Ref-810cm-1 is the standardized intensity at 810 cm.sup.1 of the corresponding wet specimen. A double bond conversion 90% is classed as sufficient.

(81) 5. Determining the Adhesion

(82) The adhesion is determined in accordance with DIN EN ISO 2409 (date: June 2013) by means of the cross-cut test. In this test, in a duplicate determination, the adhesion of the coating layer under investigation to the substrate is examined. A cross-cut tester from Byk Gardner with a 2 mm cut spacing is used manually. Subsequently, Tesa tape No. 4651 is pressed onto the damaged area and peeled off to remove the delaminated regions. The assessment is made on the basis of characteristic values ranging from 0 (minimal delamination) to 5 (very high delamination). An average value of at least 3.5 is classed as sufficient.

(83) 6. Determining the Success of Replication

(84) The success of replication is determined visually, with the percentage fraction of successfully replicated area being ascertained. The range here lies between 0% to 100% of successfully replicated area. If 100% of the area is not replicated, this means that a corresponding fraction of the area could not be removed from the embossing die, in other words that the coating B1 in the form of B1F1 remained partially adhering to the embossing tool P1, or that the coating B2 remained partially adhering to the master film B1F1.

EXAMPLES

(85) The inventive and comparative examples below serve to illustrate the invention, but should not be interpreted as imposing any restriction.

(86) Unless otherwise indicated, the amounts in parts are parts by weight and amounts in percent are in each case percentages by weight.

1. Ingredients and Materials Used

(87) Hostaphan GNcommercially available PET film with a layer thickness of 125 m. Laromer UA 9033 (L UA 9033)aliphatic urethane acrylate from BASF SE, employable as component (d) Hexanediol diacrylate (HDDA)employable as component (d) Sartomer 395 (SR 395)isodecyl acrylate from Sartomer, employable as component (d) Sartomer 502 (SR 502)TMPTA (trimethylolpropane triacrylate) with 9-fold ethoxylation, from Sartomer, employable as component (a) Sartomer 499 (SR 499)TMPTA (trimethylolpropane triacrylate) with 6-fold ethoxylation, from Sartomer, employable as component (a) Sartomer 454 (SR 454)TMPTA (trimethylolpropane triacrylate) with 3-fold ethoxylation, from Sartomer, employable as comparative component (a) TMPTA (trimethylolpropane triacrylate)employable as comparative component (a) GPTA (glyceryl propoxytriacrylate)glyceryl triacrylate with 3-fold propoxylation, employable as comparative component (a) Irgacure 184 (I-184)commercially available photoinitiator from BASF SE, employable as component (c) Irgacure TPO-L (I-TPO-L)commercially available photoinitiator from BASF SE, employable as component (c) Tego Rad 2500 (TR 2500)lubricity and antiblocking additive from Evonik (silicone acrylate), employable as component (b) Byk-SILCLEAN 3710 (BS 3710)surface additive from BYK Chemie GmbH (polyether-modified acrylic-functional polydimethylsiloxane), employavle as component (b)

2. Examples

(88) 2.1 Production of Coating Compositions (B1a) and Corresponding Comparative Coating Compositions

(89) The coating compositions were produced in accordance with tables 1a and 1b below. Coating compositions E1a to E3a as well as E4a to E6a are inventive. Coating compositions Via to V5a are comparative coating compositions. The flow times ascertained at room temperature (20 C.) are in the range from 26 to 172 s in the case of the production of E1a to E3a and Via to V5a.

(90) TABLE-US-00001 TABLE 1a Coating Component (a) or composition comparative component (a) Component (b) Component (d) Component (c) E1a SR 499 (65 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO-L (3.5 HDDA (13.5 parts) parts) E2a SR 499 (92 parts) TR 2500 (1 part) I-184 (3.5 parts) and I-TPO-L (3.5 parts) E3a SR 502 (65 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO (3.5 HDDA (13.5 parts) parts) V1a SR 499 (65 parts) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO-L (3.5 HDDA (13.5 parts) parts) V2a SR 454 (65 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO (3.5 HDDA (13.5 parts) parts) V3a TMPTA (50 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (26 parts) and and I-TPO-L (3.5 SR 395 (16 parts) parts) V4a GPTA (50 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (26 parts) and and I-TPO-L (3.5 SR 395 (16 parts) parts) V5a SR 499 (32 parts) TR 2500 (1 part) L UA 9033 I-184 (3.5 parts) (30 parts) and and I-TPO-L (3.5 HDDA (30 parts) parts)

(91) TABLE-US-00002 TABLE 1b Coating composition Component (a) Component (b) Component (d) Component (c) E4a SR 499 (65 parts) TR 2500 (0.5 parts) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO-L (3.5 HDDA (13.5 parts) parts) E5a SR 499 (65 parts) TR 2500 (2 parts) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO-L (3.5 HDDA (13.5 parts) parts) E6a SR 499 (65 parts) BS 3710 (1 part) L UA 9033 I-184 (3.5 parts) (13.5 parts) and and I-TPO-L (3.5 HDDA (13.5 parts) parts)
2.2 Production of Master Films (B1F1) Using E1a to E3a and V1a to V5a as Well as E4a to E6a

(92) A number of different master films are produced using a roll-to-plate embossing apparatus with a nickel embossing tool P1 bearing the desired positive structure. For this purpose, one each of the above-described coating compositions E1a to E3a and Via to V5a as well as E4a to E6a is applied to P1, and a PET film (F1) is applied over it (Hostaphan GN). The resulting stack of film and respective coating composition then runs through beneath a pressing roll and, still while the embossing apparatus is in contact with the coating composition of the respective stack, the coating compositions are at least partially cured by means of a UV-LED lamp. The lamp used in this case is a 365 nm, 6 W UV-LED lamp from Easytec (100% lamp power, 2 m/min, 2 passes). The at least partially cured coating together with film, with the negative structure by comparison with P1, is subsequently separated from the embossing apparatus, to give the structured film (master film). The master films are subsequently post-exposed with a UVA lamp (Panacol-Elosal UV F-900).

(93) Further, a master film is produced by using a roll-to-roll embossing apparatus having an embossing tool P1 made of nickel bearing the desired positive structure. For this purpose, the coating composition E1a described above is applied to a PET film (F1) (Hostaphan GN) and passed over the embossing tool P1 with the aid of a pressing roll. Even while the embossing apparatus is in contact with the coating composition, the at least partial curing of the coating composition is effected by a UV-LED lamp. A 365 nm, 6 W UV-LED lamp from Easytec (100% lamp power, 5 m/min) is used. Subsequently, the at least partially cured coating together with the film is separated from the embossing apparatus with the negative structure by comparison with P1, and the structured film (master film) is obtained. The master film is subsequently post-exposed with a UVA lamp (Panacol-Elosal UV F-900).

(94) 2.3 Master Films Produced

(95) In the manner described in section 2.2, various sets of master films are obtained (E1F1 to E3F1 and V1F1 to V5F1 as well as E4F1 to E6F1), additionally differing in their embossing according to the nature of the positive structure. In this case, embossing apparatuses of nickel with different positive structures were used, specifically with a nanostructure (lattice structure with a period of 430 nm and a depth of 140 nm; the respective coating composition is applied in layer thicknesses between 5-10 m to the PET film employed), a microstructure M1 (two-dimensional triangle structure with a width and height of 33 m and a space of 35 m between the structures; the respective coating composition is applied in layer thicknesses of 20 m to the PET film employed), a microstructure A (continuous two-dimensional triangular structure with a width of 45 m and a height of 13 m, the respective coating composition is applied in layer thicknesses of 20 m to the PET film used), or with a microstructure B (two-dimensional triangular structure with a height of 80 m and 115 m space between the structures, the respective coating composition being applied to the employed PET film in layer thicknesses of 110 m.

(96) The master films with the nanostructure are used for determining the modeling accuracy, the double bond conversions, and the adhesion. The master films with the microstructure M1 are used for determining the success of replicationsee. Point 2.4and also used for the production of transfer films as described below under points 2.5 to 2.7. The master films with the microstructures A or B are used for the production of transfer films as described in Section 2.8 below. For producing these master films, the coating composition E1a is used in each case and correspondingly master films E1F1 with microstructure A or B are obtained.

(97) 2.4 Investigations on the Master Films Table 2 below summarizes the investigations conducted. The investigations were each conducted in accordance with the methods described above. The symbol - within the table denotes that the particular investigation was not carried out.

(98) TABLE-US-00003 TABLE 2 DB Success of Modeling Master conversion replication accuracy film (%) Adhesion (%) (h, %) E1F1 92 3.5 100 4 E2F1 90 0.5 100 4 E3F1 95 2.5 4 V1F1 93 5 100 3 V2F1 85 1.5 85 2 V3F1 89 5 85 5 V4F1 92 5 100 4 V5F1 87 5 85 29

(99) The data show that, in the case of V2F1, V3F1 and V5F1, there is no attainment of sufficient DB conversion (DB conversion <90). With too low a DB conversion, problems may occur in the embossing both of the coating composition (B1a) and also, later on, of the coating composition (B2a). The master films E1F1, E2F1 and E3F1, conversely, show DB conversions of at least 90%.

(100) In the case of V1F1 and V4F1, the DB conversions are indeed >90%, but the adhesion achieved with these master films, just as with V3F1 and V5F1, is inadequate (cross-cut test evaluated with a rating of 5). If adhesion of the master coating on the PET film is insufficient, problems may occur during embossing both of the coating composition (B1a) and also, later on, of the coating composition (B2a). The master films E1F1, E2F1 and E3F1, conversely, all exhibit good to sufficient adhesion properties.

(101) The data additionally show that, in the case of V2F1, V3F1 and V5F1, only values of 85% are obtained in the assessment of the success of replication, since 15% of the respective coating V2, V3 and V5 could not be removed from the embossing tool. Conversely, the investigated master films E1F1 and E2F1 exhibit a replication success of 100%.

(102) Apart from V5F1, all of the master films investigated exhibit sufficient modeling accuracy, since very low contraction values are obtained consistently. Only in the case of V5F1 is a contraction of 29% obtained, which is unacceptable.

(103) In summary it can be stated that only the master films E1F1, E2F1 and E3F1 furnish good results in respect of all of the properties investigated (DB conversion, adhesion, modeling accuracy, and success of replication)

(104) 2.5 Production of Transfer Films:

(105) The master films obtained respectively with the microstructure are then each used in a roll-to-plate embossing apparatus, and a coating composition (B2a) is applied with a wet layer thickness of 20 m to the structured surface of the respective master film. The resulting stack of master film and coating composition (B2a) is lined with a TAC film to protect against oxygen. The stack obtained in turn, comprising master film, coating composition (B2a) applied thereto, and TAC film applied to the coating composition, then runs through beneath a pressing roll, in a process simultaneous with the at least partial curing of the coating composition (B2a) by a UV-LED lamp. The lamp used in this case is a 365 nm, 6 W UV-LED lamp from Easytec (100% lamp power, 2 m/min, 2 passes). In this way, following removal of the TAC film, a composite (B2B1F1) is obtained as a transfer film stack.

(106) The coating composition (B2a) employed is a commercial, radiation-curing coating composition which comprises at least one urethane acrylate, at least one photoinitiator and also commercial additives.

(107) 2.6 Production of Bonded Composites and Free Structured Films:

(108) The unstructured, coated side of the coating (B2) of the transfer film (B2B1F1) is then adhered by means of a laminating film (mount laminating film S-4705 WSA 120P from ATP; polyacrylate) to a coated steel plate. The laminating film used consists of an adhesive film K, lined on either side initially in each case with a silicone paper in order to protect against unintended sticking. For this purpose, the silicone paper is first of all peeled from one of the sides and, parallel to the direction of peeling of the silicone paper, the adhesive film is brought, with its now exposed adhesive side, onto the coated side of the coating (B2) of the transfer film (B2B1F1), by pressing the adhesive film onto B2 with a rubber roller. Similarly, then, the silicone paper is peeled off from the other side and, parallel to the direction of peeling of the silicone paper, the adhesive film is pressed by its final adhesive side, now exposed, onto a surface of the steel plate as substrate F2, using a rubber roller. The resulting composite (F2KB2B1F1) is first stored at 50 C. for 12 hours. Following this storage, the respective master film (B1F1) is peeled from the aforesaid composite, to give not only the master film but also the composite (F2KB2).

(109) In order to obtain a free structured film, the coating (B2) can be separated from the bonded steel plate (F2KB2).

(110) 2.7 Investigations on the Bonded Composites (F2KB2) or on the Free Structured Film (B2)

(111) Table 3 below summarizes the results of the investigations of the success of replication performed on the resultant transfer films, taking account of the particular master film used for embossing. The symbol - within the table denotes that the particular investigation was not carried out.

(112) TABLE-US-00004 TABLE 3 Success of replication of the embossed structure Success of Master film used replication (%) E1F1 100 E2F1 100 E3F1 100 E5F1 100 E6F1 100 V1F1 52* V2F1 100 V3F1 17 V4F1 <1 V5F1 86 *= Average value of two determinations

(113) The data show that, in the case where V3F1 and V4F1 are used, replication is only inadequate. When using V1F1 and V5F1, as well, values of only <100% are obtained when assessing the success of replication, since in these cases parts of the coating B2 could not be removed from the coatings V1 and V5 of the respective master films. Conversely, when using the investigated master films E1F1 to E3F1 and E5F1 and E6F1, a replication success of 100% is achieved.

(114) 2.8 Production of Further Transfer Films:

(115) A thermally curable coating composition (B2a) is applied with a wet layer thickness of 200 m to the structured surface of the respective master film E1F1, which carries one of the microstructures A or B. The at least partial curing of the thus obtained stack of master film and coating composition (B2a) takes place after a flash-off time of 10 minutes at room temperature (23 C.) in a commercial oven from Heraeus at 80 C. oven temperature (45 min). It is thus obtained as a stack a composite (B2B1F1) as a transfer film.

(116) The used thermally curable coating composition (B2a) is a commercially available thermosetting 2K coating composition. The mixing ratio between component 1 and component 2 is 2:1. Component 1 contains at least one polyol and commercial additives. Component 2 contains at least one polyisocyanate and commercially available additives.

(117) From the transfer films thus obtained, composites (F2KB2) are obtained by means of the procedure described under point 2.6.

(118) Table 4 below summarizes the results of the tests of the success of replication performed on the obtained transfer films taking into account each master film used for embossing.

(119) TABLE-US-00005 TABLE 4 Success of replication of the embossed structure Success of Master film used replication (%) E1F1 (with microstructure A) 100 E1F1 (with microstructure B) 100

(120) The data show that in the case of the use of the investigated master films E1F1 a replication success of 100% is achieved, even if a thermosetting coating composition is used as the coating composition (B2a).