Method for producing a structuring agent for texturing an embossable material surface, in particular a resin-containing laminate surface, and structuring agent of this kind

Abstract

A method for producing a structuring agent for texturing an embossable material surface, in particular a resin-containing laminate surface, including the steps of providing a web-shaped carrier material made of paper and/or plastic, applying a UV-curable lacquer layer made of acrylated oligomer to the carrier material, forming a three-dimensional embossed structure into the lacquer layer applied to the carrier material and curing the lacquer layer by irradiation with high-energy radiation, preferably UV light, during the molding of the embossed structure. The invention provides that before the UV-curable lacquer layer is applied at least one adhesion promoter layer including acrylated oligomer, a reactive diluent and a photoinitiator which reacts to high-energy radiation, preferably UV radiation, is applied onto the carrier material, and that the lacquer layer having the embossed structure is cured by irradiation with high-energy radiation, preferably UV light, to such an extent that, in the finished state, the structuring agent has an average Martens hardness according to DIN EN ISO 14577 in the range from 10 to 80 N/mm.sup.2, preferably in the range from 30 to 80 N/mm.sup.2, the indenter used as a test body for measuring the Martens hardness being pressed into the surface of the lacquer layer having the embossed structure. A structuring agent is also disclosed.

Claims

1. A method for producing agent an embossing die for texturing an embossable material surface of a decorative laminate: providing a carrier material made of paper and/or plastic, said carrier having a thickness of from 50 to 200 m; applying a UV-curable lacquer layer of acrylated oligomer onto the carrier material, forming a three-dimensional embossed structure into the lacquer layer applied to the carrier material, and curing the lacquer layer by irradiation with UV light during the forming of the embossed structure, wherein before the UV-curable lacquer layer is applied, at least one adhesion promoter layer comprising acrylated oligomer, a reactive diluent and a photo initiator which reacts to UV radiation, is applied onto the carrier material, and the lacquer layer having the embossed structure is cured by irradiation with UV light, to such an extent that, when finished curing, the surface of the lacquer layer of the embossing die having the embossed structure has an average Martens hardness according to DIN EN ISO 14577 in the range from 10 to 80 N/mm.sup.2, and, after curing, the lacquer layer having the embossed structure has an average roughness depth (Rz) according to DIN EN ISO 4287 of from 10 to 200 m.

2. The method according to claim 1, wherein the at least one adhesion promoter layer is applied onto the carrier material with a layer thickness in the range from 0.5 to 12 m, based on the dry state of the adhesion promoter layer.

3. The method according to claim 1 wherein the carrier material is at least partially permeable to UV light, wherein the curing of the lacquer layer is carried out by irradiation with UV light, during the forming of the embossed structure in such a way that the irradiation is carried out at least partially from the side of the carrier material facing away from the embossed structure.

4. The method according to claim 1, wherein paper is used as the carrier material, an aqueous adhesion promoter being applied onto the carrier material to produce the adhesion promoter layer, the adhesion promoter layer being dried at least in the surface region before the UV-curable lacquer layer is applied thereto, and the drying being carried out using temperatures in the range from 80 C. to 160 C.

5. The method according to claim 1, wherein a plastic film is used as the carrier material, the adhesion promoter layer being cured to such an extent via UV radiation, before the UV-curable lacquer layer is applied onto the adhesion promoter layer, that the adhesion promoter layer is solid and/or substantially non-adhesive on its surface, wherein the photo initiator of the adhesion promoter layer is suitable for absorbing light with a wavelength in the range from 250 to 350 nm, and wherein the adhesion promoter layer is cured with a UV radiation dose in the range from 60 to 200 mJ/cm.sup.2.

6. The method according to claim 1, wherein the adhesion promoter layer comprises 10 to 90% by weight of acrylated oligomer, at least 8% by weight of reactive diluent, 0.5 to 10% by weight of photo initiator which reacts to UV radiation and optionally 0.1 to 3% by weight of one or more additives selected from the group consisting of defoamers and substrate wetting agents, the amounts of all components contained in the adhesion promoter layer adding up to 100% by weight.

7. The method according to claim 1, wherein a lacquer is used for the UV-curable lacquer layer comprising 30 to 95% by weight of acrylated oligomer, 10 to 70% by weight of mono- or multifunctional monomer, 1 to 5% by weight of photo initiator, and optionally 1 to 6% by weight of one or more additives selected from the group consisting of defoamers, substrate wetting agents, release additives, waxes and anti-settling agents, wherein the amounts of all components contained in the UV-curable coating add up to 100% by weight.

8. The method according to claim 1, wherein the adhesion promoter layer and/or the lacquer used for the UV-curable lacquer layer comprises urethane acrylate, polyester acrylate, epoxy acrylate or a mixture of two or three of these acrylates as an acrylated oligomer.

9. The method according to claim 1, wherein the UV-curable lacquer layer is cured via at least one UV-light-emitting LED emitter, emitting a UV radiation power in the range from 8 to 16 W/cm.sup.2.

10. The method according to claim 1, wherein the UV-curable lacquer layer is finally cured via at least one mercury vapour medium-pressure lamp or at least one UV-C lamp, the final curing being carried out using a UV radiation dose in the range from 500 to 3,000 mJ/cm.sup.2.

11. The method according to claim 1, wherein the photo initiator of the UV-curable lacquer absorbs light with a wavelength in the range from 360 to 420 nm.

12. The method according to claim 1, wherein an embossing roller is used to form the embossed structure, the composite formed from the web like carrier material, the adhesion promoter layer and the lacquer layer being guided around the embossing roller with a wrap angle in the range from 60 to 200.

13. The method according to claim 1, wherein the embossable material surface is a resin comprising laminate surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail below with the aid of a drawing showing examples of embodiments. It shows schematically

(2) FIG. 1 a method and a device, respectively, for producing a structuring agent for texturing an embossable material surface, in particular a resin-containing laminate surface, in a side view; and

(3) FIG. 2 a further embodiment of a method and a device, respectively, for producing a structuring agent for texturing an embossable material surface, in particular a resin-containing laminate surface, in a side view.

DESCRIPTION OF THE INVENTION

(4) FIG. 1 schematically shows a device 1 which can be used to carry out the method according to the invention and on which the method according to the invention is exemplarily illustrated. By means of this device, three-dimensional structures 2, in particular reproductions of wood grain, natural stone, mosaic pattern structures and/or tile pattern structures, can be transferred from a corresponding master structure, which is designed for example in the form of an embossing roll 3, to a carrier material 5 coated with UV-curable lacquer 4.

(5) The carrier material 5 is a web-like carrier material made of paper and/or plastic that is at least partially permeable to high-energy radiation, in particular UV light. The carrier material 5 is provided as a roll 6 in wound form. For example, a film that is permeable to UV radiation and made of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC) or another plastic that is permeable to UV radiation is used as carrier material 5. The film can also be referred to as a transparent film. The thickness of the film is, for example, in the range of 50 to 200 m, preferably in the range of 75 to 125 m, particularly preferably in the range of 100 to 125 m. Alternatively, transparent paper that is permeable to UV radiation is used as the web-like carrier material 5. The basis weight of the paper is, for example, in the range from 80 to 180 g/m.sup.2, preferably in the range from 150 to 170 g/m.sup.2.

(6) A UV-curable lacquer layer 7 of acrylated oligomer is applied to the carrier material 5, into which a three-dimensional embossed structure is subsequently formed. According to the invention, at least one adhesion promoter layer 8, which is composed of acrylated oligomer, a reactive diluent and a photoinitiator that reacts to UV radiation, is applied to the carrier material 5 before the UV-curable lacquer layer 7 is applied.

(7) The adhesion promoter layer 8 contains, for example, 10 to 90% by weight, preferably 40 to 70% by weight, of acrylated oligomer, at least 8% by weight, preferably at least 20% by weight, of reactive diluent and 0.5 to 10% by weight, preferably 0.5 to 5% by weight, of photoinitiator which reacts to UV radiation.

(8) According to a preferred embodiment, the adhesion promoter used for the adhesion promoter layer 8 or the adhesion promoter layer formed therewith may have the following composition: 60 to 90% by weight of Ebercryl 4265 from the company Allnex (as an acrylated oligomer or comparable polyurethane acrylate), 10 to 30% by weight of triethylene glycol divinyl ether (e.g. Ashland Rapidure DVE-3 or comparable monomer), 5 to 10% by weight methylbenzoyl formate (MBF or comparable UV-reactive photoinitiator) and 0.1 to 3% by weight of one or more additives from a group comprising defoamers and substrate wetting agents, the quantities of all the constituents contained in the adhesion promoter layer adding up to 100% by weight.

(9) The photoinitiator is suitable, for example, for absorbing light with a wavelength in the range from 250 to 350 nm, preferably in the range from 270 to 330 nm. The adhesion promoter is applied to the web-shaped carrier material 5, for example by means of an engraved or rubberized application roll 9.

(10) If transparent paper that is permeable to UV radiation is used as the carrier material 5, the adhesion promoter is preferably applied to the paper web in aqueous form to form the adhesion promoter layer 8 and the adhesion promoter layer 8 is thermally dried before the UV-curable lacquer layer 7 is applied. Drying can be carried out, for example, by means of a radiant heater device 10 facing the adhesion promoter layer 8. Alternatively or additionally, a thermal drying device, for example a radiant heater device (not shown), can also be arranged on the side (underside or reverse side) 11 of the paper web 5 facing away from the adhesion promoter layer 8.

(11) The application quantity of the aqueous adhesion promoter is adjusted so that the adhesion promoter layer 8 in the dry state has a layer thickness in the range from 0.5 to 12 m, preferably in the range from 1 to 10 m, particularly preferably in the range from 2 to 5 m. In other words, the application quantity of the aqueous adhesion promoter on the paper web is adjusted, for example, so that the adhesion promoter layer 8 in the dry state has a weight per unit area in the range of approx. 1 to 15 g/m.sup.2, preferably in the range of approx. 4 to 7 g/m.sup.2. The drying of the adhesion promoter layer 8 takes place, for example, using temperatures in the range from 80 C. to 160 C., preferably in the range from 90 C. to 140 C., particularly preferably in the range from 100 C. to 120 C.

(12) If a plastic film web permeable to UV radiation is used instead of a paper web, the adhesion promoter is preferably applied to the plastic film web in non-aqueous form to form the adhesion promoter layer 8 and the adhesion promoter layer 8 is cured by means of UV radiation before the UV-curable lacquer layer 7 is applied until the adhesion promoter layer 8 is solid and/or essentially non-adhesive on its surface.

(13) This at least partial curing of the adhesion promoter layer 8 can be carried out, for example, by means of one or more UV lamps 12, preferably one or more UV light-emitting LED lamps, which face the adhesion promoter layer and/or are arranged on the opposite side (underside or reverse side) 11 of the web-like plastic film. The adhesion promoter layer 8 is cured, for example, with a UV radiation dose in the range from 60 to 200 mJ/cm.sup.2, preferably 100 to 160 mJ/cm.sup.2.

(14) Furthermore, it is also within the scope of the invention to carry out at least partial curing of the adhesion promoter layer 8 by combining thermal drying and radiation curing, as described above.

(15) The application quantity of the non-aqueous adhesion promoter is adjusted so that the adhesion promoter layer 8 formed therefrom has a layer thickness in the range from 0.5 to 12 m in the dry state, preferably in the range from 1 to 10 m, particularly preferably in the range from 2 to 5 m. In other words, the application quantity of the non-aqueous adhesion promoter on the plastic film web is adjusted, for example, so that the adhesion promoter layer 8 in the dry state has a weight per unit area in the range of approx. 0.3 to 15 g/m.sup.2, preferably in the range of approx. 1 to 5 g/m.sup.2.

(16) After at least partial drying or at least partial curing of the adhesion promoter layer 8, the UV-curable lacquer of acrylated oligomer is applied to it for the subsequent forming of a three-dimensional embossed structure 13.

(17) For the UV-curable lacquer layer 7, a lacquer is preferably used as a textured lacquer that contains 30 to 95% by weight acrylated oligomer, 10 to 70% by weight of mono- or multifunctional monomer, 1 to 5% by weight of photoinitiator, and optionally 1 to 6% by weight of one or more additives from a group comprising defoamers, substrate wetting agents, release additives, waxes and anti-settling agents, the amounts of all the constituents contained in the UV-curable coating adding up to 100% by weight. The photoinitiator of the UV-curable lacquer is suitable for absorbing light with a wavelength in the range from 360 to 420 nm, preferably in the range from 390 to 400 nm.

(18) The UV-curable coating can be applied by means of a roller or doctor blade application device, preferably a Commabar application device 14. The Commabar application device 14 has a special doctor blade which is formed from a roller into which a recess 14.1 of approx. 90 has been machined. This recess 14.1 makes the profile bar-shaped blade look like a comma in the side view (cross-sectional view). The adjustment of the commabar or the outlet opening limited by the commabar and the associated lacquer box can be made by changing the horizontal and vertical position as well as by changing the angle of rotation. Due to the rounding of the blade geometry, the shear forces acting on the UV-curable lacquer are lower than with conventional doctor blades. The Commabar system is advantageous when applying dilatant, viscoelastic UV lacquers. The possible variation of application weight and viscosity is particularly large with the Commabar system.

(19) The UV-curable lacquer layer is brought into contact with the embossing roll 3 or another master structure in a flowable state and therefore with relatively low pressure, so that the UV-curable lacquer reaches the recesses of the outer surface of the embossing roller 3. The composite formed from the carrier material 5, the adhesion promoter layer 8 and the lacquer layer 7 is guided around the embossing roller (master structure) 3 with a clearly defined wrap angle (see FIG. 1). The wrap angle can be in the range from 60 to 200, preferably in the range from 100 to 180.

(20) The lacquer layer 7 is hardened while it is in contact with the embossing roll (master structure) 3, i.e. while the embossed structure 13 is being formed, by irradiation with high-energy radiation, preferably UV light, the irradiation preferably taking place from the side of the radiation-permeable, web-like carrier material 5 facing away from the embossed structure 13. The irradiation device used for this purpose is denoted with 15 in FIG. 1. In addition to the irradiation in the area of the embossing roll 3 from below, the lacquer layer in the area of the embossing roll 3 can also be irradiated from at least one of the sides of the embossing roll 3.

(21) Preferably, at least one UV-light emitting LED lamp is used as the irradiation device 15. The irradiation device 15 cures the lacquer layer 7 by emitting a UV radiation power in the range from 8 to 16 W/cm.sup.2, preferably in the range from 10 to 14 W/cm.sup.2, for example approx. 12 W/cm.sup.2.

(22) The lacquer layer 7 is hardened (partially hardened) in contact with the embossing roll (master structure) 3 to such an extent that the composite of web-like carrier material 5, adhesion promoter layer 8 and lacquer layer 7 can be drawn from the embossing roll 3 with a high degree of molding accuracy. In particular, the embossed structure 13 molded into the lacquer layer can be removed from the embossing roll 3 after this hardening essentially without loss of depth and with a stable shape. Subsequently, post-curing (final curing) of the lacquer layer 7 and the underlying adhesion promoter layer 8 is carried out by means of at least one medium-pressure mercury vapor emitter 16 or at least one UV-C emitter, this post-curing or final curing preferably being carried out using a UV radiation dose in the range from 500 to 3,000 mJ/cm.sup.2. The post-curing or final curing of the structure generator 17 is carried out, for example, with a surface-specific power of approx. 200 W/cm.sup.2.

(23) After this final post-curing (final hardening), the embossed structure 13 of the texturing agent 17 produced in this way has an average roughness depth Rz according to DIN EN ISO 4287 in the range from 10 to 200 m, preferably in the range from 40 to 200 m, particularly preferably in the range from 100 to 200 m.

(24) At the end of the device 1 for carrying out the production method according to the invention, the finished structuring agent 17 is wound up.

(25) The embodiment example outlined in FIG. 2 differs from the example disclosed in FIG. 1 in that the embossing roll 3, as a hollow roll, has a radiolucent or transparent roller shell, at least one irradiation device 15 being arranged inside the embossing roll 3 and directed towards the contact area in which the UV-curable lacquer layer 7 contacts the embossing roll 3.

(26) Further examples of compositions of the adhesion promoter used in the method according to the invention or in corresponding experiments and of the radiation-curable lacquer (top coat) for shaping the embossed structure 13 of the structuring agent 17 and comparative examples are given below. In particular, average values measured in laboratory tests for the Martens hardness and measured values for the roughness depth Rz for certain web-like carrier materials are also given. Furthermore, measurement results of the cross-cut test are given.

(27) Adhesion promoters used in tests on the method according to the invention:

(28) TABLE-US-00001 Internal designation Composition V1 50 wt. % PU acrylate (difunctional), 30 wt. % HDDA, 15 wt. % EGDMA and 5 wt. % MBF; V2 37.5 wt. % PU acrylate (6-functional), 50 wt. % DPGDA, 10 wt. % HDDA and 2.5 wt. % MBF; V2B 20 wt. % PU acrylate (6-functional), 72.5 wt. % HDDA, wt. % AME0 and 2.5 wt. % MBF.

(29) Radiation-curable top lacquers (topcoats) used in tests on the process according to the invention:

(30) TABLE-US-00002 Internal designation Composition Topcoat A 76 wt. % urethane acrylate, aliphatic, 2 to 3-functional, 18 wt. % monomers, mono- or difunctional, 4 wt. % additives (defoamer, substrate wetting agent, release additive, wax, anti-settling agent), 2 wt. % photoinitiator (e.g. MAPO, BAPO, HMPP, CPK, MBF); Topcoat B 48 wt. % urethane acrylate, aromatic, 3 to 5-functional, 46 wt. % monomers, difunctional, 4 wt. % additives (defoamer, substrate wetting agent, release additive, wax, anti-settling agent), 2 wt. % photoinitiator (e.g. MAPO, BAPO, HMPP, CPK, MBF); Topcoat C 94 wt. % urethane acrylate, aliphatic, 5 to 6-functional, 4 wt. % additives (defoamer, substrate wetting agent, release additive, wax, anti-settling agent), 2 wt. % photoinitiator (e.g. MAPO, BAPO, HMPP, CPK, MBF).

(31) Martens hardness of structuring agent produced according to the invention and reference materials:

(32) TABLE-US-00003 1 PET film Hostaphan 75 m without (uncoated) 39.8 2 PET film Hostaphan 75 m V1/A 43.5 3 PET film Hostaphan 75 m V1/B 12.5 4 PET film Hostaphan 75 m V1/C 74.2 5 PET film Hostaphan 75 m V2B/A 29 6 PET film Hostaphan 75 m V2B/B 10.7 7 PET film Hostaphan 75 m V2B/C 44.6 8 paper 180 m without (uncoated) 25.8 9 paper 180 m aqueous. primer/A 44.7 10 without (top lacquer stripped top lacquer C 44.3 from film without primer)

(33) The Martens hardness was measured for the above-mentioned examples 1 to 10 using a FISCHERSCOPE HM2000S measuring device from the company Helmut Fischer in accordance with DIN EN ISO 14577, with the test range used being 300 mN/20 s. In order to illustrate the influence of the carrier material 5 on the measured surface hardness of the texturing agent 17, the Martens hardness of the carrier material (PET film Hostaphan from the company Mitsubishi or paper, respectively) was also measured on its own, i.e. without adhesion promoter and without top lacquer (see examples 1 and 8). In addition, the Martens hardness of a radiation-curable lacquer was measured separately for comparison by removing the lacquer (namely topcoat C) from a film to which the lacquer had previously been applied without primer (adhesion promoter) and then measuring it separately (see example 10).

(34) Cross-cut tests to determine the adhesion of the lacquer coating of the structuring agent 17 according to the above examples 2, 3, 4 and 6 each resulted in a characteristic value Gt of 0. This means that in these examples no flaking and thus no significant damage (de-adhesion) of the respective lacquer coating of the structuring agent 17 could be detected. In examples 5 and 7, the cross-cut tests resulted in characteristic values Gt of 2 and 1 respectively. However, these Gt values are also good characteristic values, as an average characteristic value Gt of at least 3.5 is usually still classified as a sufficient adhesion value.

(35) Comparative tests in which the UV-curable lacquer layer consisting of the above-mentioned top lacquer A, B or C was applied directly to a plastic film (75 m PET film Hostaphan from the company Mitsubishi), i.e. without using one of the above-mentioned adhesion promoters V1, V2 or V2B, each resulted in a very high degree of non-adhesion (Gt value 5) in the cross-cut test.

(36) In order to assess the molding accuracy of the embossed structure 13 of structuring agent 17 produced according to the invention, their average roughness depth Rz was measured according to DIN EN ISO 4287 and compared with the average roughness depth Rz of the respective embossing roll 3 used. One of these embossing rolls has a simulated wood structure as the master structure, while another embossing roll has a large number of negative pyramids as the master structure.

(37) TABLE-US-00004 Master structure or Measured average texturing means Lacquer quantity roughness depth Rz Embossing roll with wood 43.782 m texture as master texture Lacquered PET film Hostaphan 100 g/m.sup.2 40.36 m Lacquered parchment paper 100 g/m.sup.2 40.176 m Embossing roll with negative 150 m pyramids as master structure Lacquered PET film Hostaphan 90 g/m.sup.2 161,443 m

(38) On the basis of the above-mentioned measured values of the average roughness depth Rz, it can be seen that the molding accuracy of the embossed structure is excellent in the case of structuring agent produced according to the invention. It was also possible to determine by means of microscope images that the method according to the invention produces a true-to-original impression of the master structure of the embossing roll 3 in the embossed structure 13 of the radiation-cured top lacquer of the texturing agent 17.

(39) The execution of the invention is not limited to the embodiments shown in the schematic drawing. Rather, numerous variants are conceivable which make use of the invention disclosed in the claims even if the design differs from the examples. For example, the thermal drying or curing of the adhesion promoter layer 8 prior to the application of the UV-curable lacquer layer 7 can be carried out only from one side, for example from the top of the adhesion promoter layer 8. Furthermore, several irradiation devices, preferably LED lamps emitting UV light, can be assigned to the embossing roll 3, which are arranged both outside and inside the embossing roll 3, which has a transparent roller shell, for curing the lacquer layer 7.